Honors in “Electric Vehicles” Bachelor of Engineering

Modeling and Simulation of EHV (402034MJ)

Unit 1 : Prime Movers [Electric Motor]
Name of Author: Mr. Ravikant K. Nanwatkar
Mob: 9881955075 Mail ID: ravikant.nanwatkar@sinhgad.edu
Content of the Syllabus
• Motor Drives for EV using
1. DC Motor Drives,
2. Induction Motor Drives,
3. Permanent Magnet Brushless and
4. Switched Reluctance Motor Drives,
• Selection of Motor,
• Structural Configuration of motor layout
1. Single motor,
2. Dual motor,
3. in wheel/Hub motor,
4. Planetary-Geared Motors, etc for EV,
• Motor Safety and Maintenance,
• Motor Torque and Power Rating
Motor Drives for EV
• The electric propulsion system of EVs is responsible for converting electrical energy to mechanical energy
in such a way that the vehicle is propelled to overcome aerodynamic drag, rolling resistance drag and
kinetic resistance.
• Modern motor drive has, high-torque low-speed and constant-power high-speed regions can be achieved
through electronic control. the EV propulsion design can be more flexible, namely single or multiple
motors, with or without reduction gearing, with or without differential gearing, and axle or wheel motors.
• The electric propulsion system consists of the motor drive, transmission device and wheels. The
transmission device sometimes is optional. In fact, the motor drive, comprising of the electric motor,
power converter and electronic controller, is the core of the EV propulsion system.
The major requirements of the EV motor drive are summarized as follows,
• High instant power and high power density;
• High torque at low speeds for starting and climbing as well as high speed at low torques for cruising;
• Very wide speed range including constant-torque and constant-power regions;
• Fast torque response;
• High efficiency over wide speed and torque ranges;
• High efficiency for regenerative braking;
• High reliability and robustness for various vehicle operating conditions;
• Reasonable cost.
Systems employed for motion control are called drives. Motion control is required in industrial
as well as domestic applications like transportation system, rolling mills, paper mills, textile
mills, machine tools, fans, pumps, robots, washing machines etc. Motion control may be
translational, rotational or combination of both. Generally, a drive system is basically has a
mechanical load, a transmission system and a prime mover. The prime mover may be I.C.
engine, steam engine, turbine or electric motors. However, electric motors are predominantly
used employed as prime mover due to certain advantages.
Advantages of Electric Drives:
• Flexible control characteristics.
• Starting and braking is easy and simple
• Provides a wide range of torques over a wide range of speeds (both ac and dc motor)
• Availability of wide range of electric power
• Works to almost any type of environmental conditions
• No exhaust gases emitted
• Capable of operating in all 4 quadrants of torque –speed plane
• Can be started and accelerated at very short time.
Basic Elements of the Electric Drive Systems:

• Power source: The power source provides the energy to the drive system. It may be dc or ac
(single phase or three-phase).
• Power Converter: The converter interfaces the motor with the power source and provides the
motor with adjustable voltage, current and frequency.
• Controller: The basic function is to monitor system variables, compare them with desire
values, and then adjust the converter output until the system achieves a desired performance.
• Electric motor: The basic criterion in selecting an electric motor for a given drive application
is it meets power level and performance required by the load during steady state and dynamic
operation.
EV motor's load requirement, performance specification and operating environment are
summarized as follows:
• EV motors need to offer the maximum torque that is four to five times of the rated torque for temporary
acceleration and hill-climbing, while industrial motors generally offer the maximum torque that is twice of
the rated torque for overload operation.
• EV motors need to achieve four to five times the base speed for highway cruising, while industrial motors
generally achieve up to twice the base speed for constant-power operation.
• EV motors should be designed according to the vehicle driving profiles and drivers’ habits, while
industrial motors are usually based on a typical working mode.
• EV motors demand both high power density and good efficiency map (high efficiency over wide speed
and torque ranges) for the reduction of total vehicle weight and the extension of driving range, while
industrial motors generally need a compromise among power density, efficiency and cost with the
efficiency optimized at a rated operating point.
• EV motors desire high controllability, high steady-state accuracy and good dynamic performance for
multiple-motor coordination, while only special purpose industrial motors desire such performance.
• EV motors need to be installed in mobile vehicles with harsh operating conditions such as high
temperature, bad weather and frequent vibration, while industrial motors are generally located in fixed
places.
Difference Between a Motor and a Drive
• A motor is the mechanical or electrical device that generates the rotational or linear force
used to power a machine. A drive is the electronic device that harnesses and controls the
electrical energy sent to the motor. The drive feeds electricity into the motor in varying
amounts and at varying frequencies, thereby indirectly controlling the motor’s speed and
torque.
• There are two types of drives: a standard inverter drive for controlling speed and torque only;
and a servo drive for controlling speed and torque, as well as positioning machine
components used in applications that require complex motion.
• A motor drive controls the speed, torque, direction, and resulting horsepower of a motor. Dc
drives typically control a shunt-wound dc motor, which has separate armature and field
circuits. Ac drives control ac-induction motors and, like their dc counterparts, control speed,
torque, and horsepower.
Classification of EV motors
• The basic consideration of motor design includes magnetic loading-the peak of fundamental
component of radial flux density in the air-gap of the motor, electric loading-the total R.M.S.
• Current per unit length of periphery of the motor or ampere-turns per unit periphery, power
per unit volume and weight, torque per unit volume and weight, flux density at each part of
the magnetic circuit, speed, torque and power, losses and efficiency, and thermal design and
cooling.
• The corresponding key issues are better utilization of steel, magnet and copper, better
electromagnetic coupling, better geometry and topology, better thermal design and cooling,
understanding the limits on the motor performance, and understanding the relationship
among geometry, dimensions, parameters and performance, thus to achieve higher power per
unit weight, higher torque per unit weight and better performance.
Classification of EV motors
DC Motor Drives:
• DC motor drives have been widely used in applications requiring adjustable speed, good
speed regulation, and frequent starting, braking and reversing.
Working
• Whenever a current-carrying conductor placed in a magnetic field then there will be a force produced
in the conductor. The two fluxes oppose each other. Here, the field flux is produced by the field
winding and the armature flux is produced by the armature winding when the armature is given an
electric input.
• The direction of the flux produced by the armature conductor is determined by the right-hand thumb
rule and the direction of the armature conductor can be determined. armature flux and main field flux
will interact with each other by which the net flux will be increased towards one side and which will
be minimum on the other side.
• The increased flux on one side will be in the shape of an enlarged magnetic field or flux or like a
stretched rubber band. Therefore, this will exert a force on the surface of the conductor by which
there will be momentum in the conductor.
• As the armature is in a cylindrical shape and has a radius, therefore, a force will be created on the
surface of the armature which leads to turning or twisting which is called as production of torque.
• As the flux is zero the speed is infinity and the motor mechanically gets damaged. The speed of the
motor can be varied up to two times. We should not run the series motor at no-load conditions.
• Under light load conditions, the current drawn by the series motor will be very very small and
therefore the speed of the motor will be very very high which may lead to mechanical damage to the
motor. So, the series motor should not be operated under light load or no-load conditions.
Brushless DC Motors
• It is similar to DC motors with Permanent Magnets.
• It is called brushless because it does not have the commutator and brush arrangement.
• The commutation is done electronically in this motor because of this BLDC motors are
maintenance free.
• BLDC motors have traction characteristics like high starting torque, high efficiency around
95-98%, etc.
• BLDC motors are suitable for high power density design approach. The BLDC motors are
the most preferred motors for the electric vehicle application due to its traction
characteristics.
• BLDC motors further have two types:
1) Out-runner type BLDC Motor
2) In-runner type BLDC Motor
Out-runner type BLDC Motor:
• The rotor of the motor is present outside and the stator is present inside.
• It is also called as Hub motors because the wheel is directly connected to the exterior rotor.
• This type of motors does not require external gear system.
• In a few cases, the motor itself has inbuilt planetary gears.
• This motor makes the overall vehicle less bulky as it does not require any gear system.
• It also eliminates the space required for mounting the motor.
• There is a restriction on the motor dimensions which limits the power output in the in-
runner configuration.
• This motor is widely preferred by electric cycle manufacturers like Hullikal, Tronx, Spero,
light speed bicycles, etc.
• It is also used by two-wheeler manufacturers like 22 Motors, NDS Eco Motors, etc.
In-runner type BLDC Motor:
• In this type, the rotor of the motor is present inside and the stator is outside like
conventional motors.
• These motor require an external transmission system to transfer the power to the wheels,
because of this the out-runner configuration is little bulky when compared to the in-runner
configuration.
• Many three- wheeler manufacturers like Goenka Electric Motors, Speego Vehicles, Kinetic
Green, Volta Automotive use BLDC motors.
• Low and medium performance scooter manufacturers also use BLDC motors for propulsion.
• It is due to these reasons it is widely preferred motor for electric vehicle application.
• The main drawback is the high cost due to permanent magnets.
• Overloading the motor beyond a certain limit reduces the life of permanent magnets due to
thermal conditions.
Advantages Of DC Motor
• DC motors are smaller in size.
• These motors operate on DC supply then they can be used in electronics devices.
• DC motors are suitable for traction systems for driving heavy loads.
• DC series motors have will high starting torque.
• Wide range of speed control.
• DC Shunt motors are best suited for armature control and field control.
• DC motors have quick starting, stopping, reversing, and fast acceleration.
• DC motors are free from harmonics.
Disadvantages Of DC Motor
• DC motors have a high initial cost.
• Maintenance cost is high and increased operation due to the presence of brushes and commutator.
• Due to sparking at brush DC motors cannot operate in explosive and hazardous conditions.
• As the speed increases, the shaft gets vibrated and the armature gets damaged.
• We need converters to supply power to the motor.
Applications Of DC Motor
• DC series motors are used where high starting torque is required and variation of speed is possible. Series
motors are used in traction systems, cranes, air compressors, vacuum compressors, sewing machines, etc.
• Shunt motors are a special type of motor used where constant speed is required. These motors are used in
blowers, weaving machines, spinning machines, lifts, etc.
Summery of DC Motor Drives:
• Brushed DC motors are well known for their ability to achieve high torque at low speed
and their torque–speed characteristics suitable for the traction requirement.
• The motor speed is adjusted through varying voltage. Being suitable to propel a vehicle and
easy to be controlled, they have been used on EVs. Brushed DC motors can have two, four
or six poles depending on power output and voltage, and may have series or shunt field
windings.
• On the one hand, shunt motors have the better controllability than series motors. Separately
excited DC motors are inherently suited for field weakened operation, due to its decoupled
torque and flux control characteristics.
• On the other hand, a range of extended constant power operation is obtained by separate
field weakening. However, brushed DC motor drives have a bulky construction, low
efficiency, low reliability, and higher need of maintenance, mainly due to the presence of
the mechanical commutator and brushes.
• It is difficult to downsize brushed DC motors. This makes brushed DC motors more heavy
and expensive. Furthermore, friction between brushes and commutator restricts the
maximum motor speed.
Induction Motors
Working principal
• In a DC motor, supply is needed to be given for the stator winding as well as the rotor winding. But in
an induction motor only the stator winding is fed with an AC supply.
• Alternating flux is produced around the stator winding due to AC supply. This alternating flux revolves with
synchronous speed. The revolving flux is called as "Rotating Magnetic Field" (RMF).
• The relative speed between stator RMF and rotor conductors causes an induced emf in the rotor conductors,
according to the Faraday's law of electromagnetic induction. The rotor conductors are short circuited, and
hence rotor current is produced due to induced emf. That is why such motors are called as induction motors.
• (This action is same as that occurs in transformers, hence induction motors can be called as rotating
transformers.)
• Now, induced current in rotor will also produce alternating flux around it. This rotor flux lags behind the stator
flux. The direction of induced rotor current, according to Lenz's law, is such that it will tend to oppose the
cause of its production.
• As the cause of production of rotor current is the relative velocity between rotating stator flux and the rotor, the
rotor will try to catch up with the stator RMF. Thus the rotor rotates in the same direction as that of stator flux
to minimize the relative velocity. However, the rotor never succeeds in catching up the synchronous speed.
This is the basic working principle of induction motor of either type, single phase of 3 phase.
• The induction motors do not have a high starting toque like DC series motors under fixed
voltage and fixed frequency operation.
• But this characteristic can be altered by using various control techniques like FOC or v/f
methods.
• By using these control methods, the maximum torque is made available at the starting of the
motor which is suitable for traction application.
• Squirrel cage induction motors have a long life due to less maintenance.
• Induction motors can be designed up to an efficiency of 92-95%.
• The drawback of an induction motor is that it requires complex inverter circuit and control
of the motor is difficult.
• In permanent magnet motors, the magnets contribute to the flux density B. Therefore,
adjusting the value of B in induction motors is easy when compared to permanent magnet
motors.
• It is because in Induction motors the value of B can be adjusted by varying the voltage and
frequency (V/f) based on torque requirements. This helps in reducing the losses which in
turn improves the efficiency.
Three Phase AC Induction Motors
• Tesla Model S is the best example to prove the high performance capability of induction
motors compared to its counterparts.
• By opting for induction motors, Tesla might have wanted to eliminate the dependency on
permanent magnets.
• Even Mahindra Reva e2o uses a three phase induction motor for its propulsion.
• Major automotive manufacturers like TATA motors have planned to use Induction motors in
their cars and buses.
• The two-wheeler manufacturer TVS motors will be launching an electric scooter which uses
induction motor for its propulsion.
• Induction motors are the preferred choice for performance oriented electric vehicles due to
its cheap cost.
• The other advantage is that it can withstand rugged environmental conditions.
• Due to these advantages, the Indian railways has started replacing its DC motors with AC
induction motors.
Three Phase AC Induction Motors
Advantages of induction motor:
• It is a very cheap cost compare to the other motors.
• This motor is a highly efficient motor. The efficiency of the induction motor is varying from
85 to 95%.
• The maintenance of an induction motor is very less compared to the DC motor and
synchronous motor.
• The working of an induction motor is very simple and unique.
• The construction of an induction motor is robust and also sturdy.
• In this motor, only the AC source requires to operate. It does not require DC excitation like
the use of a synchronous motor.
• In this motor, the speed variation from no load to rated load is very less.
• The induction motor is famous for its durability. This makes it the ideal machine for many of
the uses. This results in the motor run for many years with no cost and maintenance.
• Due to the absence of brushes, there are no sparks in the motor. It can also be operated in
hazardous conditions.
• Unlike synchronous motors, a 3 phase induction motor has high starting torque, good speed
regulation, and also reasonable overload capacity.
Disadvantages of induction motor:
• The power factor of the motor is very low during light load conditions.
• During light load conditions, it operates at a very low power factor.
• It has low efficiency.
• Single-phase induction motor is not self-starting. It requires some auxiliary for stating.
• This motor cannot use in such applications where the uses of high starting torque is
necessary like traction and lifting weight.
• The change in the speed of the motor is very low loading different loading conditions, so the
speed control of IM is difficult.
• The speed of the motor is very low during different loading conditioned so, the speed
control of the induction motor is difficult.
Applications of single-phase induction Applications of three-phase induction
motors motors
• Pumps • Lifts
• Compressors • Cranes
• Small fans • Hoists
• Mixers • Large exhaust fans
• Toys • Lathe machines
• High-speed vacuums • Crushers
• Electric shavers • Oil extracting mills
• Drilling machines • Textiles
• Commercial electric and hybrid vehicles
Summery of Induction motor drives:
• Induction motors are of simple construction, reliability, ruggedness, low maintenance, low cost, and ability to
operate in hostile environments. The absence of brush friction permits the motors to raise the limit for
maximum speed, and the higher rating of speed enable these motors to develop high output.
• Speed variations of induction motors are achieved by changing the frequency of voltage. Field orientation
control (FOC) of induction motor can decouple its torque control from field control. This allows the motor to
behave in the same manner as a separately excited dc motor.
• This motor, however, does not suffer from the same speed limitations as in the dc motor. Extended speed range
operation beyond base speed is accomplished by flux weakening, once the motor has reached its rated power
capability. A properly designed induction motor, e.g., spindle motor, with field oriented control can achieve
field weakened range of 3-5 times the base speed.
• However, the controllers of induction motors are at higher cost than the ones of DC motors. Furthermore, the
presence of a breakdown torque limits its extended constant-power operation. At the critical speed, the
breakdown torque is reached. Generally, for a conventional IM, the critical speed is around two times the
synchronous one.
• Any attempt to operate the motor at the maximum current beyond this speed will stall the motor. Although FOC
may extend constant power operation, it results in an increased breakdown torque thereby resulting in an over-
sizing of the motor.
• In addition, efficiency at a high speed range may suffer in addition to the fact that IMs efficiency is inherently
lower than that of permanent magnetic (PM) motors and switched reluctance motors (SRMs) due to the absence
of rotor winding and rotor copper losses.
Permanent Magnet Brushless Motor:
• By using high energy permanent magnet as the field excitation mechanism a permanent
magnet motor drive can be potentially designed with high power density, high speed and
high operation efficiency for EV and HEV applications.
• BLDC motor works on the principle similar to that of a Brushed DC motor. The Lorentz
force law which states that whenever a current carrying conductor placed in a magnetic field
it experiences a force. As a consequence of reaction force, the magnet will experience an
equal and opposite force. In the BLDC motor, the current carrying conductor is
stationary and the permanent magnet is moving.
• When the stator coils get a supply from source, it becomes electromagnet and starts
producing the uniform field in the air gap. Though the source of supply is DC, switching
makes to generate an AC voltage waveform with trapezoidal shape. Due to the force of
interaction between electromagnet stator and permanent magnet rotor, the rotor continues to
rotate.
• With the switching of windings as High and Low signals, corresponding winding energized
as North and South poles. The permanent magnet rotor with North and South poles align
with stator poles which causes the motor to rotate.
Advantages of Brushless DC motor
• Less overall maintenance due to absence of brushes
• Reduced size with far superior thermal characteristics
• Higher speed range and lower electric noise generation.
• It has no mechanical commutator and associated problems
• High efficiency and high output power to size ratio due to the use of permanent magnet rotor
• High speed of operation even in loaded and unloaded conditions due to the absence of
brushes that limits the speed
• Smaller motor geometry and lighter in weight than both brushed type DC and induction AC
motors.
• Long life as no inspection and maintenance is required for commutator system
• Higher dynamic response due to low inertia and carrying windings in the stator
• Less electromagnetic interference
• Low noise due to absence of brushes
Limitations of Brushless DC motor
• These motors are costly
• Electronic controller required control this motor is expensive
• Requires complex drive circuitry
• Need of additional sensors
Applications of Brushless DC motor
• Brushless DC motors (BLDC) use for a wide variety of application requirements such as
varying loads, constant loads and positioning applications in the fields of industrial control,
automotive, aviation, automation systems, health care equipments etc.
• Computer hard drives and DVD/CD players
• Electric vehicles, hybrid vehicles, and electric bicycles
• Industrial robots, CNC machine tools, and simple belt driven systems
• Washing machines, compressors and dryers
• Fans, pumps and blowers.
Permanent magnet direct current motor: When field windings and magnetic poles of
conventional DCMs are replaced with PMs, a PM-DCM is established. PM-DCMs show
higher power density and efficiency, but it needs more maintenance and exhibits low life and
torque fluctuation due to the commutator and brush system; these are still the concerns to be
solved for EV applications.
Permanent magnet brushless DC motor: PM-BLDCM is a special PMSM structurally and
theoretically, but its windings are concentrated normally and the stator current wave shape is
trapezoidal, instead of sinusoidal in SPM. The commutator-brush system is not required.
However, the torque ripple and noise appear during electrical commutation, and it is difficult
to achieve the maximum speed beyond twice the base speed.
Permanent magnet hybrid excitation motor: By adding excitation windings to PMSM, the
motor has both PMs and excitation windings and becomes a hybrid excited motor, which is
PM-HEM. This motor has the minimum flux leakage, high flux density in the air gap, high
power density, and good torque-speed characteristics. However, its topology and control are
relatively complex owing to two separate excitations.
Summery of PM BLDC motor drives:
• PM BLDC motor drives are specifically known for their high efficiency and high power
density. Using permanent magnet, the motors can eliminate the need for energy to produce
magnetic poles. So they are capable of achieve higher efficiency than DC motors, induction
motors and SRMs.
• Furthermore, heat is efficiently dissipated to the surroundings. The speed range may be
extended three to four times over the base speed if for a PM BLDC motor a conduction-
angle control is used .
• PM BLDC motor drives have the other drawbacks in that the magnet is expensive and that
the mechanical strength of the magnet makes it difficult to build a large torque into the
motor. PM BLDC motors have no brush to limit speed, but questions persist over the fixing
intensity of the magnet because it restricts the maximum speed if the motors are of an inner-
rotor type.
• Furthermore, this motor suffers from a rather limited field weakening capability. This is due
to the presence of the PM field which can only be weakened through production of a stator
field component which opposes the rotor magnetic field.
• Nevertheless, extended constant power operation is possible through the advancing of the
commutation angle.
Switched Reluctance Motors (SRM)
• An electric motor like SRM (switched reluctance motor) runs through reluctance torque.
Different from the types of common brushed DC motor, power can be transmitted to
windings within the stator instead of the rotor. An alternate name of this motor is VRM
(Variable Reluctance Motor). For a better operation of this motor, it uses a switching
inverter. The control characteristics of this motor are the same as dc motors which
electronically commutated. These motors are applicable where sizing, as well as
horsepower (hp) to weight, is critical.
• This motor simplifies its mechanical design to restrict the flow of current toward a rotary
part; however, it complicates the design because some kind of switching system must be
employed to transmit the power toward the different windings. This mechanical design can
also be used for a generator. The load can be switched toward the coils within the sequence
to coordinate the flow of current through the rotation. So these generators can also run at
high speed as compared with conventional types of motors because the armature is made
like a single piece of magnetizable material like a slotted cylinder.
Switched Reluctance Motors (SRM)
Working Principle
• The working principle of the switched reluctance motor is, it works on the principle of
variable reluctance that means, the rotor of this motor constantly tries to align through the
lowest reluctance lane.
• The formation of the rotary magnetic field can be done using the circuit of power
electronics switching.
• In this, the magnetic circuit’s reluctance can mainly depend on the air gap. Therefore, by
modifying the air gap among the rotor as well as a stator, we can also modify the reluctance
of this motor. Here, reluctance can be defined as resistance toward the magnetic flux. For
Electrical circuits, reluctance is the combination of resistance as well as the magnetic
circuit.
• The operating of SRM (switched reluctance motor) can be done through switching currents
within the stator windings of the motor by making changes within the magnetic circuit.
This circuit can be formed through the stator as well as the rotor of the motor.
• Once the poles of the stator & the rotor are out of position, then the magnetic circuit among
them includes a high reluctance.
• When the pairs of the pole in the stator are switched, the rotor switches to connect through the activated stator
poles to reduce the reluctance of the circuit. When the stator poles are switched then they should be exactly
timed to make sure that it happens because the rotor pole is moving toward to connect with the activated stator
pole.
• The main difference between SRMs (switched reluctance motors) & stepper motors is the construction of
stator. In an SRM, the phases are autonomous with each other that means, if one otherwise more phases stop
working, then the motor will operable even though by decreased torque output.
• Switched reluctance motors generate more clear noise as compared with stepper motors. The main source of
noise can be the distortion of the stator because of the radial forces that happen once the pairs of stator poles
are activated. These pairs are attracted to cause radial forces to alter the stator.
The characteristics of the switched reluctance motor include the following.
• This kind of reluctance motor is a 1-phase or 3-phase
• Speed control of this motor is simple.
• The triggering circuit can be changed to get high speed
• It operates with a DC supply once used with an inverter.
• Once the firing angle of any switching device can be changed then different speeds can be achieved.
• Control of one phase is independent of the other two phases.
• The unutilized energy fed to the motor can be retrieved by using the feedback diodes. This improves efficiency.
The advantages of a switched reluctance motor include the following.
• These motors are very simple & the rotors in this motor are extremely strong
• These motors are applicable for high-speed applications.
• The VFDs (variable frequency drives) of this motor are somewhat simpler as compared with
conventional VFDs.
• This motor doesn’t use any additional ventilation system when the stator, as well as rotor
slots, is projected. So the airflow can be maintained among the slots.
• These are less expensive because of the nonexistence of permanent magnets.
• Fault tolerance is high
• This motor works with a simple two-phase or three-phase pulse generator.
• Phase losses do not change the operation of the motor.
• Once the phase sequence is changed then the motor direction will be changed.
• Inertia Ratio or High Torque
• Self-starting without using additional arrangements
The disadvantages of a switched reluctance motor include the following.
• Switched reluctance motors have less torque capacity & normally these motors are noisy.
• While operating this motor at high speed, it creates a torque ripple.
• High noise level
• It uses an external rotor position sensor
• These are applicable for medium to high speed, low-cost applications wherever controllability & shaft or noise
torque ripple are not dangerous.
• This motor generates harmonics when it operates at high speed, so to reduce this, large size capacitors need to
install.
• Since the nonexistence of a permanent magnet, the SRM has to carry a high i/p current to increase the
necessity of converter KVA.
The applications of switched reluctance motors include the following.
• These types of motors are used as an alternative for induction motors in different applications wherever the
operating conditions of this motor do not suit them.
• In textile machinery like towel looms, rapier looms, etc
• Used in electric vehicles
• Oilfield machinery like beam pumps, vertical pumps, well testing machinery, etc.
• Mining machinery like conveyors, shearers, winches, ball mills, boring machines, coal crushers, etc.
• Used in all kinds of mechanical presses like screw presses.
These motors are used in miscellaneous applications which include the following.
• Machine tools like vertical lathes, planers, drilling machines, etc.
• Coil winding as well as unwinding equipment
• General machinery like pumps, fans, compressors, etc.
• Equipment used in paper mills
• Machinery used for food mixing
• Rolling mill for metals
• Lifting machines such as winches, lifts, conveyors, etc
• Manufacturing of plastic-like extrusion, injection molding devices
• Power generation device like load control using wind turbine rotor blade
• Used in domestic appliances like vacuum cleaners, washing machines, fans, etc.
• These motors have many benefits in different applications. At present, the linear version of
this motor has been implemented to process the same attributes as well as prospects by
owing their design & high force density.
Summery of SRM motor drives:
• SRM drives are gaining much interest and are recognized to have a potential for EV applications.
These motor drives have definite advantages such as simple and rugged construction, fault-tolerant
operation, simple control, and outstanding torque–speed characteristics.
• SRM drives can inherently operate with an extremely long constant-power range. The torque-speed
characteristics of SRM drives match very well with the EV load characteristics.
• The SRM drive has high speed operation capability with a wide constant power region. The motor
has high starting torque and high torque-inertia ratio. The rotor structure is extremely simple without
any windings, magnets, commutators or brushes.
• The fault tolerance of the motor is also extremely good. Because of its simple construction and low
rotor inertia, SRM has very rapid acceleration and extremely high speed operation.
• Because of its wide speed range operation, SRM is particularly suitable for gearless operation in EV
propulsion.
• In addition, the absence of magnetic sources (i.e., windings or permanent magnets) on the rotor
makes SRM relatively easy to cool and insensitive to high temperatures.
• The latter is of prime interest in automotive applications, which demand operation under harsh
ambient conditions. An extended range of 2-3 times the base speed is usually possible using an
appropriate control.
• The disadvantages of SRM drives are that they have to suffer from torque ripple and acoustic noise.
However, these are not potential problems that prohibit its use for Evs application.
Review and Development of Electric Motor Systems and Electric Powertrains for New
Energy Vehicles
Index DC Motor Induction Permanent magnet Switched Reluctance
Motor induction motor Motor Drives
Efficiency Good Better Best Good

Speed Good Best Better Best

Size Good Better Best Better

Reliability Good Better Best Best

Control Best Better Good Better

simplicity
Performance Good Better Best Better
Comparative analysis of motor drives:
• DC motor drives will continue to be used in EVs because DC motor drives are available at the
lowest cost. From the point of view of efficiency, PM BLDC motor drives are the best choice. SRM
drives have the lowest weight among four types of motor drives for Evs. If the choice of motor
drives for EVs is determined by three factors that are weight, efficiency and cost, it is clear that
SRM drives are the best choice for EVs. Except for the efficiency, weight and cost, SRM drives
also have the ascendancy in the aspects of cooling, maximum speed, fault tolerance, and reliability.
• after evaluating tradeoffs between the efficiency, weight and cost, cooling, maximum speed, fault
tolerance, safety and reliability for brushed DC motor drives, IM drives, PM BLDC motor drives,
and SRM drives, SRM drives are the most appropriate candidate by evaluating an optimal balance.
• In the aspect of efficiency, PM BLDC motor drives are better than SRM drives, IM drives and
brushed DC motor drives; The weight of SRM drives is lower than PM BLDC motor, IM, and
brushed DC motor drives; Brushed DC motor drives have the lowest cost for these four types of
motor drives; Taking into account the aforementioned three criteria, SRM drives are
superior to other three types of motor drives. Furthermore, SRM drives also have the ascendancy in
the aspects of cooling, maximum speed, fault tolerance, safety, and reliability. Therefore, SRM
drives are ideally suitable for nowadays EV applications.
Selection of Motor
• The electric motors used for automotive applications should have characteristics like high
starting torque, high power density, good efficiency, etc.
• For selecting the appropriate electric vehicle motors, one has to first list down the
requirements of the performance that the vehicle has to meet, the operating conditions and
the cost associated with it.
• For example, go-kart vehicle and two-wheeler applications which requires less performance
(mostly less than 3 kW) at a low cost, it is good to go with BLDC Hub motors.
• For three-wheelers and two-wheelers, it is also good to choose BLDC motors with or
without an external gear system.
• For high power applications like performance two-wheelers, cars, buses, trucks the ideal
motor choice would be PMSM or Induction motors. Once the synchronous reluctance motor
and switched reluctance motor are made cost effective as PMSM or Induction motors, then
one can have more options of motor types for electric vehicle application.
• In terms of maturity of technology, induction motor and dc electric motors has highest
mature technology for being used propulsion system and maturity of technology of these
motors are slightly greater than permanent magnet brushless electric motor and switched
reluctance motor.
• Drive requires less maintenance and breakdown should be minimum.
• From reliability point of view, induction motor and switched reluctance motors are most
reliable motor drive followed by permanent magnet brushless motor.
• DC drive have least reliability among all other drives. In terms of power density permanent
magnet brushless motor have high power density as compare to both induction motor and
switched reluctance motor.
• Again DC drive has least power density. Apart from these factors cost factor is also an
important characteristics that should be taken under consideration.
• Cost factor is most important because its makes things commercially viable.
• In terms of cost factor, induction motor most cost efficient followed by dc and switched
reluctance motors.
Motor selection criteria
• Vehicle characteristics: The properties of the vehicle such as size, weight, overload and
aerodynamics are crucial vehicle characteristics that will ultimately determine speed,
torque and power requirements of the electric motor. These aspects will help understand the
effects of the operating conditions of the vehicle and are essential to the selection of the
right powertrain.
• Driving cycles: How is the vehicle being used is also very important. What will be the
usual driving cycles of the vehicle? Will it be driven in an urban area with many stops?
Will it be driven on long distances with only a few stops? All of this will help to determine
the vehicle configuration (series hybrid, parallel hybrid, all electric) and battery pack size
and ultimately impact the choice of the powertrain.
• Vehicle configuration (electric, hybrid): Is the vehicle hybrid or full electric? If hybrid, is it
parallel hybrid or series hybrid? As a rule of thumb, if the vehicle routes are not predictable
or if it will be driven on long distances, usually the hybrid architecture is preferred. The full
electric configuration is well suited for in city driving where the distance is not too long
between charging points, the speed is low and the amount of stops is high.
• Maximal speed: What is the targeted maximum speed of the vehicle? How long does it
have to be sustained, maybe it is used only for passing? What are the gearbox ratios
available (if using a gearbox) and the differential ratio? What is the rolling radius of the
wheel? All of these questions must be answered and used in the calculations to determine
the maximum speed the electric motor has to reach in your application.
• Maximal torque: The maximum torque enables the vehicle to start in a given slope. You
need to find the highest grade the vehicle will need to ascend. Using that grade, it is
possible to calculate the highest torque required by the electric motor considering the
differential and gearbox (if using a gearbox!). Maximal weight is also to be taken into
consideration.
• Maximal power: Some grades need to be climbed at a minimum speed some others don’t.
Sometimes the maximum power is found simply at maximum speed (this is the case where
the vehicle as a large frontal area or goes at very high speed). This translates to having a
motor powerful enough to go through all the different conditions the vehicle can be
submitted to! The maximum power enables the vehicle to reach and maintain a constant
speed under stringent slope and speed conditions.
• Battery Capacity: The battery capacity is typically calculated using a simulator to go through a
reference cycle typical of the usage of the vehicle. The simulator can output the consumption of the
vehicle in kWh/km. From that value, the capacity of the battery can be calculated by multiplying it
with the desired range.
• Battery Voltage: The battery voltage is dependent on the size of the vehicle. As the battery
voltage increases, the current output is lowered. So in the cases where the vehicle continuous power
is high like in bigger vehicles, you want to keep the size of the conductors at a manageable level by
increasing the battery voltage. There are normally two ranges of voltages: 300-450Vdc and 500-
750Vdc. This is because of the voltage limitation of IGBTs used in the motor controller and the two
main standard voltages available for them: 600Vdc and 1200Vdc.
• Gearbox or direct-drive: Will the powertrain architecture require a gearbox? Do you want to
save the costs related to implementing a transmission or/and simplify your system? TM4’s
SUMO electric powertrain offer a direct-drive approach: the high torque/low speed of the motor
allows it to directly interface with standard axle differentials without the need for an intermediate
gearbox. While improving system reliability and reducing overall maintenance costs, removing
the transmission in an electric vehicle also increases the powertrain’s efficiency considerably,
allowing optimal use of the energy stored in the battery pack.
• Cost: Last but not least, what is your budget? In a previous blog post, we reviewed the
different electric motor technologies available on the market, their pros and cons and their
relative usage in electric vehicles.
EV configurations
• Previously, the EV was mainly converted from the ICEV, simply replacing the combustion engine
by the electric motor while retaining all the other components. This converted EV has been fading
out because of the drawback of heavy weight, loss of flexibility and degradation of performance.
• Compared with the ICEV, the configuration of the EV is particularly flexible.
• The energy flow in the EV is mainly via flexible electrical wires rather than bolted flanges or rigid
shafts.
• Different EV propulsion arrangements (such as independent four-wheel and in-wheel drives)
involve a significant difference in the system configuration.
• Different EV energy sources (such as batteries and fuel cells) have different weights, sizes and
shapes.
• Figure shows the general configuration of the EV, consisting of three major subsystems-electric
propulsion, energy source and auxiliary.
• The electric propulsion subsystem comprises the electronic controller, power converter, electric
motor, mechanical transmission and driving wheels.
• The energy source subsystem involves the energy source, energy management unit and energy
refueling unit.
• The auxiliary subsystem consists of the power steering unit, temperature control unit and auxiliary
power supply.
EV configurations
EV configurations
• Based on the control inputs from the brake and accelerator pedals, the electronic controller
provides proper control signals to switch on or off the power devices of the power
converter which functions to regulate power flow between the electric motor and energy
source.
• The backward power flow is due to regenerative braking of the EV and this regenerative
energy can be stored provided the energy source is receptive.
• most available EV batteries (except some metal/air batteries) as well as capacitors and
flywheels readily accept regenerative energy.
• The energy management unit cooperates with the electronic controller to control
regenerative braking and its energy recovery.
• It also works with the energy refuelling unit to control refuelling and to monitor usability of
the energy source.
• The auxiliary power supply provides the necessary power with different voltage levels for
all EV auxiliaries, especially the temperature control and power steering units. Besides the
brake and accelerator, the steering wheel is another key control input of the EV.
• Based on its angular position, the power steering unit can determine how sharply the
vehicle should turn.
• For a modern EV, a three-phase induction motor is typically selected.
• The corresponding power converter is a three-phase PWM inverter.
• In general, the mechanical transmission is based on fixed gearing and a differential. Also, a
nickel-metal hydride (Ni-MH) battery is also typically selected as the energy
• source.
• The corresponding refueling unit becomes a battery charger.
• The temperature control unit generally consists of a cooler and/or a heater, depending on
the climate of a particular country. This typical set-up is shown in Figure.
• At present, there are many possible EV configurations due to the variations in electric
propulsion and energy sources.
• Focusing on those variations in electric propulsion, there are six typical alternatives as
shown in Figure.
• Figure (a) shows the first alternative which is a direct extension of the existing ICEV
adopting longitudinal front-engine front-wheel drive. It consists of an electric motor, a
clutch, a gearbox and a differential. The clutch is a mechanical device which is used to
connect or disconnect power flow from the electric motor to the wheels. The gearbox is
another mechanical device which consists of a set of gears with different gear ratios. By
incorporating both clutch and gearbox, the driver can shift the gear ratios and hence the
torque going to the wheels. The wheels have high torque low speed in the lower gears and
high speed low torque in the higher gears. The differential is a mechanical device which
enables the wheels to be driven at different speeds when cornering-the outer wheel covering
a greater distance than the inner wheel.
• By replacing the gearbox with fixed gearing and hence removing the clutch, both the weight
and size of the mechanical transmission can be greatly reduced. Figure (b) shows this
arrangement which consists of an electric motor, fixed gearing and a differential. Notice that
this EV configuration is not suitable for the ICEV as the engine by itself, without the clutch
and gearbox, cannot offer the desired torque-speed characteristics.
• Similar to the concept of transverse front-engine front-wheel drive of the existing ICEV, the
electric motor, fixed gearing and differential are integrated into a single assembly, while both
axles point at both driving wheels. Figure (c) show this configuration which is in fact most
commonly adopted by modern EVs.
• Besides the mechanical means, the differential action of an EV when cornering can be
electronically provided by two electric motors operating at different speeds. Figure (d)
shows this dual-motor configuration in which two electric motors separately drive the
driving wheels via fixed gearing.
• In order to further shorten the mechanical transmission path from the electric motor to the
driving wheel, the electric motor can be placed inside a wheel. This arrangement is the so-
called in-wheel drive. Figure (e) shows this configuration in which fixed planetary gearing is
employed to reduce the motor speed to the desired wheel speed. It should be noted that
planetary gearing offers the advantages of a high speed-reduction ratio as well as an inline
arrangement of input and output shafts.
• By fully abandoning any mechanical gearing, the in-wheel drive can be realized by installing
a low-speed outer-rotor electric motor inside a wheel. Figure (f) shows this gearless
arrangement in which the outer rotor is directly mounted on the wheel rim. Thus, speed
control of the electric motor is equivalent to the control of the wheel speed and hence the
vehicle speed.
• Apart from the variations in electric propulsion, there are other EV configurations due to the
variations in energy sources (batteries, fuel cells, capacitors and flywheels). Six typical
alternatives are shown in Figure 2.
• Figure (a) shows a basic battery-powered configuration that is almost exclusively adopted by
existing EVs. The battery may be distributed around the vehicle, packed together at the
vehicle back or located beneath the vehicle chassis. This battery should be able to offer
reasonable specific energy and specific power as well as being able to accept regenerative
energy during braking. Notice that both high specific energy and high specific power are
desirable for EV applications as the former governs the driving range while the latter dictates
the acceleration rate and hill-climbing capability. A battery having a design compromised
between specific energy and specific power is generally adopted in this configuration.
• Instead of using a compromised battery design, two different batteries (one is optimized for
high specific energy while another for high specific power) can be used simultaneously in an
EV. Figure (b) shows the basic arrangement of this battery & battery hybrid energy source.
This arrangement not only decouples the requirements on energy and power but also affords
an opportunity to use those mechanically rechargeable batteries which cannot accept
regenerative energy during braking or downhill.
• Differing from the battery which is an energy storage device, the fuel cell is an energy
generation device. The operating principle of fuel cells is a reverse process of electrolysis-
combining hydrogen and oxygen gases to form electricity and water. Hydrogen gas can be
stored in an on-board tank whereas oxygen gas is simply extracted from air. Since the fuel
cell can offer high specific energy but cannot accept regenerative energy, it is preferable to
combine it with a battery with high specific power and high energy receptivity. Figure (c)
shows this arrangement which is denoted as a fuel cell & battery hybrid energy source.
• Rather than storing it as a compressed gas, a liquid or a metal hydride, hydrogen can be on-
board generated from ambient-temperature liquid fuels such as methanol or even petrol. As
shown in Figure (d), a mini reformer is installed in the EV to produce on line the necessary
hydrogen gas for the fuel cell.
• In contrast to the fuel cell & battery hybrid in which the battery is purposely selected to offer
high specific power and high energy receptivity, the battery in the battery & capacitor hybrid
is aimed to have high specific energy. This is because a capacitor can inherently offer a much
higher specific power and energy receptivity than a battery. Since the available capacitors for
EV application, usually termed as ultracapacitors, are of relatively low voltage level, an
additional dc-dc power converter is needed to interface between the battery and capacitor
terminals. Figure (e) shows this configuration.
• For EVs converted from ICEVs, the use of variable gearing was claimed to be natural
because both gearbox and clutch are already present and their maintenance costs are minor.
• the use of variable gearing can enhance the electric motor achieving regenerative braking
and high efficiency operation over a wide speed range.
• Fixed-gearing transmission is usually based on planetary gearing. A planetary gear set
consists of a sun gear, several planet gears, a planet gear carrier and a ring gear. It takes the
advantages of strong, compact, high efficiency, high speed reduction ratio and in-line
arrangement of input and output shafts over the conventional parallel-shaft variable gear set.
• Thus, the removal of this variable gearing can significantly reduce the overall complexity,
size, weight and cost of the transmission. Moreover, modern electric motors with the use of
fixed gearing can readily offer the desired torque-speed characteristics for vehicular
operation.
• Figure shows typical force-speed characteristics of an EV with fixed gearing, consisting of
constant-torque operation for acceleration and hill climbing as well as constant-power
operation for high-speed cruising. Moreover, the absence of gear changing (irrespective of
whether it is manual or automatic) can greatly enhance smooth driving and transmission
efficiency. Therefore, modern EVs almost exclusively adopt fixed gearing rather than
variable gearing.
• For EVs, output characteristics of electric motors differ from those of ICEs.
• Typically, the electric motor eliminates the necessity for a motor to be idle while at a stop, it
is allowed to produce large torque at low speed, and it offers a wide range of speed
variations.
• It may be possible to develop lighter, more compact, more efficient systems by taking
advantages of the characteristics of electric motors.
• The choices of drivetrain systems in an EV include mainly:
propulsion mode, such as front-wheel drive, rear-wheel drive, or four-wheel drive;
number of electric motors in a vehicle;
drive approach, for instance, indirect or direct drive; and
number of transmission gear levels.
• Therefore, the possible drivetrain systems in EVs have the following six configurations.
1)Conventional Type
2)Transmission-less Type
3) Cascade Type
4)In-wheel Type with Reduction Gears and Direct-drive Type
5)Four- wheel Direct-drive Type
6)Planetary gear type
Conventional Type Transmission-less Type

Cascade Type In-wheel Type with Reduction Gears and Direct-drive

Four- wheel Direct-drive Type Planetary gear type

ICEV force-speed characteristics with five-speed transmission. EV force-speed characteristics with fixed gearing.
• Similar to the capacitor, the flywheel is another emerging energy storage device which can
offer high specific power and high energy receptivity. It should be noted that the flywheel for
EV applications is different from the conventional design which is characterized by low
speed and massive size. In contrast, it is lightweight and operates at ultrahigh speeds under a
vacuum environment.
• This ultrahigh-speed flywheel is incorporated into the rotor of an electric machine which
operates at motoring and generating modes when converting electrical energy to and from
kinetic energy, respectively. The corresponding configuration is shown in Figure (f) in which
the battery is selected to offer high specific energy. Since this flywheel is preferably
incorporated into an ac machine which is brushless and can offer a higher efficiency than
that of a dc machine, an additional ac-dc converter is needed to interface between the battery
and flywheel terminals.
Fixed And Variable Gearing (Planetary gearing)
• Fixed gearing means that there is a fixed gear ratio between the propulsion device (ICE or
electric motor) to the driving wheels.
• In contrast, variable gearing involves shifting between different gear ratios, this can be
accomplished by using a combination of clutch and gearbox.
• The purpose of variable gearing is to provide multiple-speed transmission (achieving wide
ranges of speed and torque using different gear ratios).
• Generally, four- or live-speed transmission is used for passenger cars, and up to 16-speed
transmission for trucks.
• When the clutch is engaged, the propulsion device and the gearbox are coupled together and
power transmission is enabled. When it is disengaged manually or automatically, the power
transmission is interrupted so that the gear ratio in the gearbox can be shifted.
• For ICEVs, there is no alternative to the use of variable gearing as the ICE cannot offer the
desired torque-speed characteristics (such as high torque for hill climbing and high speed for
cruising) without using multiple-speed transmission).
• For EVs, the employment of variable gearing to achieve multiple-speed transmission used to
be controversial. For EVs converted from ICEVs, the use of variable gearing was claimed to
be natural because both gearbox and clutch are already present and their maintenance costs
are minor.
• However, the concept of converted EVs is almost obsolete as it cannot fully utilize the
flexibility and potentiality offered by EVs.
• It was also claimed that the use of variable gearing can enhance the electric motor achieving
regenerative braking and high efficiency operation over a wide speed range. With the
advances of power electronics and control algorithms, both regenerative braking and high
efficiency operation of electric motors can be easily achieved by electronic means rather than
mechanical means.
• Fixed-gearing transmission is usually based on planetary gearing. A planetary gear set
consists of a sun gear, several planet gears, a planet gear carrier and a ring gear. It takes the
advantages of strong, compact, high efficiency, high speed- reduction ratio and in-line
arrangement of input and output shafts over the conventional parallel-shaft variable gear set.
• Thus, the removal of this variable gearing can significantly reduce the overall complexity,
size, weight and cost of the transmission. Moreover, modem electric motors with the use of
fixed gearing can readily offer the desired torque-speed characteristics for vehicular
operation.
• fixed gearing, consisting of constant-torque operation for acceleration and hill climbing as
well as constant-power operation for high-speed cruising. Moreover, the absence of gear
changing (irrespective of whether it is manual or automatic) can greatly enhance smooth
driving and transmission efficiency. Therefore, modern EVs almost exclusively adopt fixed
gearing rather than variable gearing.
Single- And Multiple-motor Drives
• A differential is a standard component for conventional vehicles and this technology can be
carried forward to the LV field.
• When a vehicle is rounding a curved road, the outer wheel needs to travel on a larger radius
than the inner wheel.
• Thus, the differential adjusts the relative speeds or the wheels; otherwise, the wheels will slip
which causes tire wear, steering difficulties and poor road holding.
• For all ICEVs, whether front- or rear-wheel drive, a differential is mandatory.
• Figure shows a typical differential in which pinion spider gears can rotate on their shaft,
allowing axle side gears to turn at different speeds.
• For EVs, it is possible to dispense with a mechanical differential.
• By separately coupling two or even four electric motors to the driving wheels, the speed of
each wheel can be independently controlled in such a way that the differential action can be
electronically achieved when comparing.
• Figure shows a typical dual- motor drive with an electronic differential.
• This arrangement is smaller and lighter than the mechanical counterpart.
• Unlike the choice between variable gearing and fixed gearing, the selection of either a
single-motor drive with a differential or a multiple-motor drive without a differential is still
controversial.
• Positively, the removal of a mechanical differential can reduce the overall size and weight
while (he electronic differential can accurately control (he wheel speeds so as to achieve
better performance during cornering.
• Negatively, the use of an additional electric motor and power converter causes an increase in
the initial cost while the reliability of the electronic controller to accurately control two
electric motors at various driving conditions is to be observed.
• In recent years, the reliability of this electronic controller has been greatly improved by
incorporating the capability of fault tolerance.
• For example, the electronic controller consists of three micro processors.
• Two of them are used to separately control the motor speeds for the left and right wheels
while the remaining one is used for system control and coordination. All of them watch one
another by using a watchdog to improve the reliability.
In wheel drive configuration:
• By placing an electric motor inside the wheel, the in-wheel motor has the definite advantage
that the mechanical transmission path between the electric motor and the wheel can be
minimized or even eliminated, depending whether the electric motor is a high-speed inner-
rotor type or a low-speed outer-rotor type.
• When it is a high-speed inner-rotor motor, a fixed speed-reduction gear becomes necessary
to attain a realistic wheel speed. In general, a high speed-reduction planetary gear set is
adopted which is mounted between the motor shaft and the wheel rim.
• Typically, this motor is purposely designed to operate up to about 10000rpm so as to give a
higher power density.
• This maximum speed is limited by the friction and windage losses as well as the
transmission tolerance.
• Thus, the corresponding planetary gear ratio is of about 10:l to provide the wheel speed
range from zero to about 1000 rpm.
• On the other hand, the transmission can be totally removed when a low-speed outer-rotor
motor is used.
• The key is that this outer rotor itself is the wheel rim and the motor speed is equivalent Lu
the wheel speed, and no gears are required.
• Figure shows these two in-wheel drives, both employing a permanent-magnet brushless
motor.
• Although different types of electric motors can be adopted, the permanent-magnet brushless
machine is most attractive because of its outstanding power density.
• The high-speed inner-rotor motor has the advantages of smaller size, lighter weight and
lower cost, but needs an additional planetary gear set.
• On the other hand, the low-speed outer-rotor motor has the definite advantage of simplicity
and is gearless, but the motor suffers from the drawbacks of increased size, weight and cost
because of the low-speed design.
• Both types of in-wheel motors have been applied to modem EVs (Shimizu. 1995).
Motor Safety and Maintenance:
A well and carefully designed motor maintenance program, when correctly used, can be
summed up as preventive maintenance, predictive maintenance and reactive maintenance.
Inspection cycles depend upon the type of motor and the conditions under which it operates.
Motors need maintenance regularly in order.
kinds of maintenance:
• Preventive maintenance – to prevent operating problems and make sure that the motor
continuously provides reliable operation.
• Predictive maintenance – to ensure that the right kind of maintenance is carried out at the
right time.
• Reactive maintenance – to repair and replace the motor when a failure occurs.
Reactive Maintenance
• When motors fail, it is important to examine the motor and find out where in the motor it
happened and why it happened. Normally, good preventive maintenance can prevent failure.
• If the failure is caused by a weak component or inadequate maintenance, then all similar
equipment has to be examined in order to prevent the same failure from occurring elsewhere
inthe motor or in the entire system.
Predictive Maintenance
The objective of predictive maintenance of electric motor maintenance is to reduce
maintenance costs by detecting problems at an early stage and deal with them. Observations
of motor temperature, vibrations, etc. are only a few examples of data that can help predict
when the motor needs to be repaired or replaced. Following are some of the tests that provide
the necessary data about the state of the motor.
• Bearing considerations
• Insulation considerations
• Ground insulation test
• Cleaning and drying stator windings
• Surge test
• High potential testing – HIPOT
• DC high potential ground test
• AC high potential phase to ground test and phase-to-phase test
• Motor temperature
• Thermographic inspection
Electric Motor Safety:
Maintaining a safe work environment is paramount in industrial settings that involve high-voltage
infrastructure and rapidly moving components. Proper electric motor safety is an essential step
toward achieving trouble-free operation. Safety practices span across motor installation, everyday
operation, and maintenance. It is necessary to develop and consistently follow proper safety
procedures during each phase to achieve the best outcomes for your company and personnel.
With the right approach, the risk of accident can be minimized, and a safe and productive
working environment maintained.
Motor Operation Safety
One of the best ways to spot problems with a motor in advance is for operators to use sight, smell
and temperature to detect abnormal circumstances. However, this can be dangerous unless
operators are properly informed. A motor's surface can be extremely hot during normal operation,
especially after sudden changes in the load that draw unusually high current, and this temperature
can persist well after the motor has been stopped. Correct safety gear should be used around
running motors, and fingers and other objects kept away from ventilation ports and other points
of entry into the motor. Everyone should keep a safe distance from moving or rotating
components of the motor or driven load. When power outages occur, make sure that the motor
power is cut off so that it does not start unexpectedly when power returns.
Motor Installation Safety
• Before installing motor or developing electric motor safety procedures for your
application, it is essential to become familiar with local and national safety codes related to
your industry, as well as risk factors specific to the type of motor you have purchased.
• Please read the information provided by the manufacturer and always follow their
recommendations. After developing comprehensive safety procedures for your operation,
ensure that all operators and technicians involved are familiar with the procedures and
apply them consistently. Following the right steps during the installation of the motor
helps prevent accidents that can cause injury and damage to infrastructure.
• Before installing the motor, inspect it thoroughly for defects or damage. If any issues are
found, contact the seller before commencing installation. To reduce the risk of accident,
check that the motor characteristics are adequate for the requirements of the application
and that the voltage and connections on the motor match the power supply.
• When installing the motor, ensure that it is properly grounded and all connections are tight.
This helps protect against electrical shock if the motor connects with the skin.
Install all necessary safety measures such as thermal protection and electrical fuses, which
protect the motor and prevent potential accidents such as fires caused by overheating.
• Ensure that the motor is securely mounted and properly aligned and connected to the load.
Before start-up, it is advisable to run the motor in-place without a load to ensure that it has
been installed correctly. This is a good time to review safety procedures for the operator and
relevant personnel, including start-up, shutdown and emergency stop procedures.
• During normal operation of the motor, including start-up and shutdown, it is essential to
develop consistent procedures that protect the safety of not just the motor but any personnel
in the area. When starting a motor, make sure that all personnel in the area are alert and
aware of it.
Motor Maintenance Safety
• Whether routine or not, electric motor maintenance involves repeatedly handling and
testing the motor.
• Maintenance personnel work near hot and rapidly moving components. Besides being
qualified to disassemble and service the motor, maintenance personnel should be trained in
proper power lockout procedures, safety gear, first aid and any relevant safety codes.
• This ensures that maintenance is a low risk operation and productivity can be restored as
quickly and safely as possible when a fault occurs. Locking out power before working on
the motor is extremely important, and it is not enough to simply switch it off.
• Power can be suddenly and unexpectedly restored if the motor was stopped by a thermal
protector, which can automatically re-connect power when the motor has cooled down.
• The motor may also be inadvertently switched on by someone unaware. Proper power
lockout involves physically locking the main power switch in the off position, for example,
by enabling each technician to apply their own padlock before working on the motor.
• The main power switch should also be clearly labeled with a warning to ensure that
operators know that maintenance is being performed.
• Before handling the motor, ensure that the work environment is safe and that the motor has
been fully de-energized.
• Capacitors can store a lethal charge and must be properly drained if they are to be handled.
Ensure that the motor has cooled down sufficiently so that it does not present a risk of burn.
Check the work area for pools of liquid or leaked lubricant, increasing the risk of an
accident.
Motor Torque and Power Rating
• Power rating for electrical machines indicates the required supply voltage for smooth
running of that machine, it also shows the permissible maximum amount of current which
can easily flows through the machine and there will be a chance of breakdown in the
machine if those parameters goes beyond this limit.
• When the motor have insufficient rating, there will be frequent damages and shut downs
due to over loading.
• if the power rating of a motor is decided liberally, the extra initial cost and then loss of
energy due to operation below rated power makes this choice totally uneconomical.
• Another essential criteria of electrical motor power rating is that, during operation of motor,
heat is produced and it is inevitable due to I2R loss in the circuit and friction within the
motor. So, the ventilation system of the motor should be designed very carefully, to
dissipate the generated heat as quickly as possible.
• the main objectives of selecting and finding out motor power rating are To obtain the
suitable thermal model of motor and design the machine properly and for Finding out motor
duty class, also to Calculating motor ratings for various classes of duty.
Selection of Motor Power Rating:
• Selection of power rating is important to achieve economy with reliability.
• Improper selection of motor power rating results extra initial cost and extra loss of energy
due to the operation below rated power makes the choice uneconomical.
• Furthermore, induction and synchronous motors operate at a low power factor when
operating below the rated power.
• During operation of the machine, heat is produced due to losses and temperature rises.
An amount of developed heat is dissipated into the atmosphere. When the dissipation of
heat is equal to the developed heat, then it is said to be equilibrium condition. "Motor
temperature then reaches a steady state value.
• Steady state temperature depends on power loss, which in turn depends on the output power
of the machine. Since temperature rise has a direct relation with the output power, it is
termed thermal loading on the machine.
• Steady state temperature varies in different parts of the machine. It is usually high is the
windings because loss density in conductors is high and dissipation is slow; and the
conductors which are wrapped in insulating material are partly embedded in slots and thus
are not directly exposed to the cooling air.
Motor Torque and Power Rating
• Torque is the rotational equivalence of linear force. Power is the rate of doing work. The
relation between torque and power is directly proportional to each other.
• The power of a rotating object can be mathematically written as the scalar product of torque
and angular velocity. i.e. Power P = τ.ω Where, P is the power (work done per unit time),
τ is the torque (rotational ability of a body), ω is the angular velocity(rate of change of
angular displacement).
• By taking the voltage and multiplying it by the associated current, the power can be
determined. A watt (W) is a unit of power defined as one Joule per second. For a DC source
the calculation is simply the voltage times the current: W = V x A.
• To calculate load torque, multiply the force (F) by the distance away from the rotational
axis, which is the radius of the pulley (r). If the mass of the load (blue box) is 20 Newtons,
and the radius of the pulley is 5 cm away, then the required torque for the application is 20
N x 0.05 m = 1 Nm.
 Assignment No: 1
1. Define motor dives for electric vehicles with its advantage and requirements?
2. Explain Basic Elements of the Electric Drive Systems with neat sketch?
3. Explain EV motor's load requirement, performance specification and operating
environment?
4. Classify EV motor drives with its comparative analysis?
5. Explain DC motor drives with its working principal, advantages, disadvantages and
applications?
6. Explain Induction motor drives with its working principal, advantages, disadvantages and
applications?
7. Explain Permanent Magnet Brushless motor drives with its working principal, advantages,
disadvantages and applications?
8. Explain Switched Reluctance motor drives with its working principal, advantages,
disadvantages and applications?
9. Compare electric motor drives on basis of following,
 Efficiency
 Speed
 Size
 Reliability
 Control stability
 Performance
10. List and explain motor selection criteria for electric vehicles?
11. What do you mean by EV configuration, explain with suitable block diagram?
12. Explain any two EV configurations due to variation in electric propulsion?
13. Explain any two EV configurations due to variation in energy sources?
14. Explain Fixed and Variable Gearing (Planetary gearing)?
15. Explain Single- And Multiple-motor Drives configuration?
16. Explain In wheel drive configuration
17. Explain significance of Motor Safety and Maintenance with its types?
18. Explain the following
 Electric Motor Safety:
 Motor Operation Safety
 Motor Installation Safety
 Motor Maintenance Safety
19. Explain significance of Motor Torque and Power Rating?
20. Explain the Selection criteria of Motor Power Rating?
Honors in “Electric Vehicles” Bachelor of Engineering
Modeling and Simulation of EHV (402034MJ)
Unit 2 : Energy Storage Systems [Battery/Cell Pack]
Name of Author: Mr. Ravikant K. Nanwatkar
Mob: 9881955075 Mail ID: ravikant.nanwatkar@sinhgad.edu
Content of the Syllabus
• Types and Packs with respect to
 Construction
 Working
 Comparison
 Selection (lead-acid, nickel based, lithium-based batteries)
• Noise Factors
• Battery Packs design against Noise and Vibration exposure
• Vibration exposure (Mode shapes)
• Vehicle Dynamics
• Battery Pack
• Cooling System and Thermal Management.
Introduction:
• “Energy storages” are defined as the devices that store energy, deliver energy outside
(discharge), and accept energy from outside (charge).
• There are several types of energy storages that have been proposed for electric vehicle (EV)
and hybrid electric vehicle (HEV) applications. These energy storages, so far, mainly include
chemical batteries, ultracapacitors or supercapacitors, and ultrahigh-speed flywheels and the
fuel cell.
• There are a number of requirements for energy storage applied in an automotive application,
such as specific energy, specific power, efficiency, maintenance requirement, management,
cost, environmental adaptation and friendliness, and safety.
• For allocation on an EV, specific energy is the first consideration since it limits the vehicle
range. On the other hand, for HEV applications, specific energy becomes less important and
specific power is the first consideration, because all the energy is from the energy source
(engine or fuel cell) and sufficient power is needed to ensure vehicle performance,
particularly during acceleration, hill climbing, and regenerative braking. Of course, other
requirements should be fully considered in vehicle drive train development.
• Classification of Storage Technologies, By Energy Type
• Comparison of Power Output (in watts) and Energy Consumption (in watt-hours) for
Various Energy Storage Technologies
• Differentiating Characteristics of Different Battery Technologies
• Present and Future Battery Technologies
• Schematic of A Battery Energy Storage System
Energy Storage System Components
• The battery system consists of the battery pack, which connects multiple cells to appropriate voltage
and capacity; the battery management system (BMS); and the battery thermal management system
(B-TMS). The BMS protects the cells from harmful operation, in terms of voltage, temperature, and
current, to achieve reliable and safe operation, and balances varying cell states-of-charge (SOCs)
within a serial connection. The B-TMS controls the temperature of the cells according to their
specifications in terms of absolute values and temperature gradients within the pack.
• The components required for the reliable operation of the overall system are system control and
monitoring, the energy management system (EMS), and system thermal management. System control
and monitoring is general (IT) monitoring, which is partly combined into the overall supervisory
control and data acquisition (SCADA) system but may also include fire protection or alarm units. The
EMS is responsible for system power flow control, management, and distribution. System thermal
management controls all functions related to the heating, ventilation, and air-conditioning of the
containment system.
• The power electronics can be grouped into the conversion unit, which converts the power flow
between the grid and the battery, and the required control and monitoring components voltage sensing
units and thermal management of power electronics components (fan cooling).
Battery Technologies:
Constructional details of Batteries
Lead acid battery:
Container of Lead Acid Battery
• This jar component is made of ebonite, lead-coated wood, glass, bituminous hard rubber,
ceramic materials, or forged plastic, both of which are mounted on the surface to prevent
any electrolyte discharge. In the bottom portion of the container, there are four ribs, two of
which are mounted on the positive plate and the others on the negative plate.
• The prism serves as a foundation for both plates while also protecting them from short-
circuiting. The materials used in the container's construction should not contain sulphuric
acid, should not bend or permeate, and should not carry any impurities that could cause
electrolyte harm.
Active Component of Lead Acid Battery
• An active component is one that actively participates in the chemical reaction processes
that occur in the battery, mostly during charging and discharging. The following are the
active ingredients:
• Peroxide of lead & ndash; It is a beneficial active ingredient.
• Sponge lead is the negative active portion of the system.
• Sulphuric acid, diluted – This is mostly used as an electrolyte.
Plates of Lead Acid Battery
• The plates in a lead acid battery are built in a variety of ways, but they are all made up of the
same types of grid, which is made up of active components and lead. The grid is essential for
establishing current conductivity and distributing equal quantities of current to the active
components. There would be loosening of the active variable if the distribution is unequal.
There are two types of plates in this battery. Plante/formed plates and Faure/pasted plates are
the two types.
• The shaped plates are mostly used in static batteries, and they are both heavy and costly.
However, even in continual charging and discharging cycles, they have a long lifespan and are
unlikely to lose their active components. This has a low capacity-to-weight ratio.
• Although the pasted procedure is more commonly used to create negative plates than positive
plates, it is often used to create positive plates. The negative active aspect is more complex,
and the charging and discharging mechanisms are slightly altered.
Separators of Lead Acid Battery
• Porous rubber, treated leadwood, and glass fiber are used to make these thin boards. The
separators are used to provide active insulation between the plates. In one rim, they have a
grooved form, while the other sides are flat.
• Battery Edges of Lead Acid Battery
• It has 17.5 mm and 16 mm diameter positive and negative tips, respectively.
• These batteries mostly comprise Electrodes, Lead plates, and an electrolyte which are the basic
composition of a Lead-acid battery.
• Between the positive and negative electrodes, there are separators that allow ions to flow and
hence complete the circuit of battery composition.
• In AGM type, the separators in replaced with glass fiber mat soaked in electrolyte. This increases
the exchange or passing of gasses produced during the charging and discharging process.
• For this purpose, the electrolyte in AGM is replaced from liquid to semi saturated type. While
electrolyte in the most basic construction of the lead-acid battery is a mixture of sulfuric acid and
water(Distilled).
• In VRLA batteries, which are basically sealed batteries, vents are provided for the release of gases
produced inside the battery.
• These (VRLA) batteries are also called gel batteries, we have seen these most commonly in
household devices like insect rackets.
• Due to the gel-type electrolyte, the advantages of AGM and VRLA are the same. These all make
them mostly used batteries in extreme conditions, as they have low freezing and high boiling
points than basic (wet) or AGM types.
• These all advantages of the AGM and VRLA make them maintenance-free as they do not require
watering and gas valve for gas blow off.
• There are many uses of the lead-acid battery,
These are used from small devices like an
insect racket to big and heavy machinery like a
forklift.
• All types of automobiles use the lead-acid
battery either SLA or VRLA for ignition of
engine and electric uses. Also, these batteries
need to be recharged with both CC & CV
techniques for a better life cycle.
• Most of the electric toys used lead-acid
batteries also in the robotics field we use the
lead-acid battery for most of the low-cost
projects.
• These are also used in heavy machinery like
Forklift in factories and industries which
require drawing a large amount of current in a
very short time.
Advantages of lead acid battery:
• The main and most important advantage of the lead-acid battery is the cost over the other types of batteries.
If we calculate the price of a lead-acid battery in terms of watt/per hour, is rather very cheap and cost-effective
in all types of batteries.
• Secondly, the construction and packaging of the lead-acid battery are tough & rigid which overall all increases
its durability over other batteries
• Also, these batteries can be recharged, and mostly the type of which is used in homes or UPS can easily be used
as they require only water refilling as maintenance.
• Further, these batteries have the capability of delivering large current to load and appliances, hence these are
more popular among high power devices and tools.
• Also, if the battery is overcharged or discharged the gasses can easily escape either through the gas valve or the
water opening timely despite other batteries which leak or get puffed up.
Disadvantages:
• Most importantly, these batteries type has the lowest energy density which makes them non-ideal for portable
and mobile devices or in simple words handy devices.
• The electrolyte is dangerous and quite risky while transporting these batteries, a these may leak or spill in
between.
• Another disadvantage of these types is that you cannot use them just after the charging or just after water
refilling charging as you need to wait for 12-14 hrs for voltage stabilization.
• Although they are the most recyclable battery type, the material used in these LEAD(Pb) is toxic which can
cause harm if improperly recycle.
Ni-Cd Batteries:
• These batteries are similar to other cell or cylindrical type batteries, but the construction and effects are different
from others.
• Unlike Lead-Acid batteries, they come in a cylindrical package and a nominal voltage of around 1.2V to 1.4V.
These need to be connected in series and parallel for making the appropriate battery pack for the power supply.
• But they also have some characteristics similar to Lead-Acid battery, like they can deliver high current at their
full capacity. This even doesn’t affect their life and performance cycle.
• Along with this they can adapt to fast and easy charging even if you charge them after a long time. But in the
recommendation, they must be taken into use in tasks that require periodic usage, or due to their self-power loss,
they may discharge overtime and get damaged.
• The construction of these batteries is rather quite compact as compared to a lead-acid battery. They
come in two types or sizes which are mostly used, AA size and D size, but the construction for both is
the same.
• The batteries are enclosed, or they have metal packaging with a self-sealing plate, including a self-
sealing safety valve at the positive terminal.
• The positive and negative terminal electrodes are separated from each other by a separator, but both
electrodes are rolled in the form of a spiral in the metal casing.
• The electrolyte is of some alkali solution, which separates both positive and negative electrode.
• The positive electrode is made up of NiO(OH) and the negative electrode is of Cd. These both are
rolled up as stated above with electrolyte in between them as medium for passing the ions, with the
separator sandwiched between both the electrode layers.
Applications of nickel cadmium battery :
• The main or most common application of the Ni-Cd battery is forming battery packs of the desired
value by arranging them into series and parallel.
• Single cells are used in toys and household devices like RC toys and electric trimmers.
• The smaller button cell construction of these types of batteries is also used in handheld devices or in
BIOS memory backup batteries in computers.
• vehicles as battery packs nowadays as these can provide large current as a lead-acid batteries without
affecting their capacity or battery life.
Advantages:
• First of all they can adapt to fast, quick and easy charging with any balanced charger available or them.
Also, theses doesn’t affect their life cycle or capacity, even using after along period of time.
• Secondly, they have high energy density as compared to Lead acid battery. The AA and D Size battery
packages can offer a same amount of power as a Lead-Acid battery, but in a smaller package or space.
• Even though the material used in the construction is not as durable and strong as Lead-Acid battery, yet
they are quite durable and robust.
• They are also recyclable through thermal treatment under vacuum to recollect the Cd. Ni is also recycled
in the form of Ni-Fe alloy.
• If the battery is overcharged then the excess water above the limit of safety valve, which is formed during
the process, it released in vapour state.
Disadvantages:
• The most important and harmful disadvantage of these batteries is that they are formed or the composition
of the electrodes is of toxic materials. Which is discharged in the environment during the recycle or and
other ways can be harmful to the environment.
• Secondly, if the battery is overcharged then the excess water will be released from the safety valve, but it
will affect its capacity.
• This type of battery is also prone to memory effect, which is caused by the same charging and discharging
cycles of the battery regularly.
• These batteries also self discharge at a rate of 20% per month under identical conditions.
Ni-MH Battery
• Ni-MH which stands for Nickel-Metal Hydride Batteries.
• These batteries are more popular than Ni-Cd due to 3-4 times more capacity, which overall increases
their energy density of them.
• The sixes and packages of the Ni-MH batteries are similar to the Ni-Cd batteries, but the current
rating is much more than Ni-Cd batteries
• These are identical to alkaline batteries and even can be used as their replacement, the only issue is of
the slightly less voltage.
• the full name of NI-MH battery is nickel metal hydrite battery.
• The construction of the Ni-MH batteries are similar to the Ni-Cd batteries, but they are both different
in the material and separators used.
• The positive electrode is made of the same material as Ni-Cd, or NiO(OH), while the negative
electrode is made of the Hydrogen absorbing alloy instead of Cadmium.
• The electrolyte, in this case, is Potassium Hydroxide (KOH) which is also filled in between both
electrodes which are rolled up in the form of a spiral as a Ni-Cd battery separated by a separator.
• These are also capable of delivering high current as similar to Ni-Cd, which is an advantage of them
over alkaline batteries in single charge use.
• Furthermore, these also have the self-sealing safety valve for the release of gasses during the
overcharge process, like in case of Ni-Cd batteries construction.
Ni-MH Battery
Applications of NI-MH battery :
• It’s most of the applications are similar to the Ni-Cd batteries. Due to its more popular AA and D-size and large
current rating, it is commonly found in various battery packs.
• In RC Toys and consumer electronics used in a house, also in power tools like electric drills and cutter due to
their large current supplying capability.
• It is also used in Vehicles as battery packs instead of Lead-Acid batteries or in electric vehicles as an alternative
to Li-Ion batteries which are used conventionally.
• Despite these, it is also used in older laptops in place of Li-Ion and in cell phone as a portable power source with
higher power capacity.
Advantages:
• The main advantage of these batteries is the more capacity than the Ni-Cd batteries, which is great in terms of energy density.
• The material used in manufacturing the batteries is not as toxic as Ni-Cd, so it is more environmentally friendly than Ni-Cd
ones.
• There are many ways of charging these batteries like either monitoring changing voltage or temperature, or you can also use
trickle charging method.
• In changing voltage or temperature techniques the voltage or temperature changes are being monitored over time and according
to the datasheet of the battery the current of C value is set.
• In the trickle charging method, the battery is charged constantly at 0.1C current. But this method is for a long time and if
overcharged can reduce battery life.
• For safety features, it has a bimetallic resettable fuse that opens if either the current or the temperature is too high and closes
again when it is under a suitable range.
• They also have a relatively low self-discharge rate, which is also an advantage of using them over Ni-Cd batteries.
Disadvantages:
• The main disadvantage of these batteries is that they have a low life cycle, also after a few hundred charges you can witness
the drop in their capacity.
• if you over-discharge these batteries then these may also show reverse polarity which can permanently damage the batteries.
• Also, it is advised either to use appropriate power battery packs for power tools or if you used underrated power battery
packs then the life cycle of individuals may shorten.
• Due to it having high energy density than Ni-Cd ones, these also have a high cost than those, which can be a bit costly for
large scale.
• It is recommended to use desired battery balanced charges for charging the batteries, or it may damage the batteries
permanently due to more complex algorithm charging than Ni-Cd.
Li-Po Battery
• This is one of the most famous, mostly used batteries in projects. Due to its high capacity and wide range of
sizes and availability.
• Li-Po or Lithium-ion Polymer battery is another type of battery with polymer electrolyte instead of conventional
Liquid or semi-liquid electrode.
• These batteries work on the principal of intercalation and de-intercalation between positive and negative lithium
electrodes.
• These batteries are rather very cheap as compared to the Ni-Cd and Ni-MH cells also they come in thin to thick
sizes which make them ideal for using in small spaces.
• The construction of the Li-Po is not spiral as in the case of Ni-Cd and Ni-MH, but both electrodes are
individually wrapped but both the electrodes are of lithium only.
• For separating both the electrodes, a separator of material like polythene or polypropylene is used, which is
microporous and allows the ions to exchange.
• The positive electrode is usually a mixture of 3 parts that are lithium with transition metal oxide, a conductive
additive, and a poly binder.
• The negative electrode is similar to the positive electrode i.e., the mixture of 3 parts the only difference is that
there is a mixture of carbon with lithium.
• The electrolyte is a polymer as stated above instead of conventional liquid or semi-liquid electrolyte, but this
doesn’t affect the capacity or life.
• The outer covering or the pouch in which the battery is packed is la layer of aluminium foil sandwiched
between two polymers.
Applications of lipo battery:
• These batteries have very high and most demanding usages. Due to their various size and
capacity options, they are 1st choice for any project.
• They are used in most RC flying toys, as they require lightweight and high-capacity batteries
with high current ratings.
• Nowadays, these batteries are also used in various household and handheld devices due to their
compactness and less spacing-taking capabilities.
• Also used in electric vehicles as a replacement of the Li-Ion, Ni-Cd & Ni-MH cells as these are
quite costly and require a decent and fixed amount of space per cell.
• Moreover also used in UPS and jump starters as a combination of cells, as the combination can
supply large current in emergency situations.
Advantages:
• The main advantage of these batteries is the shape and sizes of the batter and the high energy as
compared to Ni-Cd and Ni-MH batteries if compared on the same weight and volume bases.
• The wide range of choices and C rating along with S&P battery packs are a big advantage over
other battery types.
• Along with these, batteries have low internal resistance which allows them to deliver high current
during required times such as RC toys.
• They have higher energy density than that of Ni-Cd and Ni-MH batteries, which are costly. These
batteries can over more amount of power at the same cost as that of a cell of Ni-Cd or Ni-MH ones.
• The terminals of these batteries are easily soldered unlike cell packaging of any other battery as those
require either a Spot Welder or some sandpaper rubbing and then soldering.
Disadvantages:
• The main disadvantage of these batteries is that they puffed up are kept full charge or sometimes also
leak, leaving a foul smell around them.
• These batteries need s to be charged at CC/CV methods or the cell may damage over time or lose its
capacity.
• Also, if you short circuit the battery by chance, the battery may cause fire and or may explode in
certain situations.
• If these batteries are used at low temperature like below 10 °C then you’ll see a degradation in their
performance and capacity, same as for high temperature like above 50 °C these batteries have a high
chance of exploding.
• The terminals, if soldered without any heat sink or use of thick wires the point or terminals may tear
off, and you may damage your battery.
• High capacity battery needs constant a CC/CV charger and a battery monitor with corresponded to
each cell especially for drones and RC planes.
Li- ion battery:
• The shape and sizes of these batteries are usually AA or AAA sizes, but also they are custom-made in various sizes
on demand, like as found in mobile phones.
• These batteries have the highest energy density among all batteries and are relatively costlier than any other type,
but like coin has two sides, these have advantages also.
• The nominal or normal voltage of any battery size of Li-Ion battery is 3.7V and if you charge the battery you need
to follow the CC/CV methods for each cell to ensure their battery life.
• The construction of a lithium-ion battery consists of numerous individual cells, each with the same structure. It
contains the following components:
• Positive electrode: The cathode consists of lithium metal oxide, which may contain variable amounts of nickel,
manganese and cobalt. These metal oxides are also called transition metals.
• Negative electrode: The anode is usually made of graphite.
• Electrolyte: In order for the lithium ions to move as charge carriers in the cell, anhydrous electrolytes are also
included. These contain salts such as lithium hexafluorophosphate dissolved in an aprotic solvent such as diethyl
carbonate. In lithium polymer batteries, a polymer of polyvinylidene fluoride or polyvinylidene fluoride-
hexafluoropropylene is also used at this point.
• Separator: To prevent short circuits, a separator made of nonwovens or polymer-films is installed between the
electrodes. The separator is permeable to lithium ions and can absorb large quantities.
• The design allows lithium to move back and forth between the electrodes in ionized form. Depending on the
electrode materials used, lithium-ion batteries are divided into different groups. Operation remains the same in
each, but the energy density, cell voltage, temperature sensitivity, capacity, and charge capacity and discharge
current can vary with different transition metal ions.
Li- ion battery:
Li- ion battery:
Li- ion battery (lipo battery Construction):
• As these batteries are commonly found in either AA or AAA size, the construction of bases on these two.
Also, in some places, we’ll give references for other sizes.
• The positive electrode of these batteries is mostly made of Metal Oxide, which can be of one of these 3
materials. A layered oxide such as lithium cobalt oxide, polyanion such as Lithium Iron Phosphate, or a
spinel such as lithium manganese oxide.
• The negative electrode is made of carbon, mostly graphite, which in its fully lithiated state of LiC6 has a
capacity of about 372mAh/g.
• The electrolyte in these batteries is a lithium salt in an organic solvent, as for the separator between the
electrodes it is basically polyethylene or polypropylene.
• The basic outer covering that is found in cells is of metals case without bulged surface as in normal batteries,
whereas large cells have threaded terminals for screwing the wires and connectors.
Applications of lipo battery:
• These are mostly used and very popular battery, and it has numerous application and uses. The highest
energy density and cost-to-energy ratio make them ideal for usage.
• The most common use which everyone has is the mobile phones. Modern smartphones require a large power
capacity battery but less weight, a Li-Ion battery is ideal for these.
• Secondly, modern laptops like MacBooks and book-type laptops and tabs are also the major field of
application of these batteries.
• Power tools and Hand-held devices which are used in houses are also very common uses of Li-Ion batteries,
• Wireless devices and automobiles are also a growing field of usage of the Li-Ion batteries. The cell, of AA
and AAA sizes, are most common.
The structure of a lithium-ion battery can be manufactured as:
• Lithium-polymer batteries: The electrolyte used is a polymer-based film with a gel-like
consistency. This structure makes it possible to manufacture particularly small batteries
(less than 0.1 mm thick) and in various designs. With an energy density of up to 180
Wh/kg, they are very powerful, but mechanically, electrically and thermally sensitive.
• Lithium cobalt dioxide batteries: The positive electrode of this type of battery is made of
lithium cobalt dioxide. The anode is made of graphite. These types of batteries are prone to
thermal runaway when overloaded.
• Lithium titanate batteries: Negative electrodes are not made of graphite, but of sintered
lithium titan spinel. These enable a superfast-charging capacity as well as operation
at temperatures as low as -40°C. The positive electrodes are again made of lithium
titanium oxide.
• Lithium iron phosphate batteries: Cells each have a cathode made of lithium iron
phosphate. The electrolyte is present in solid form. These batteries have a lower
energy density of up to 110 Wh/kg, but are not prone to thermal runaway if mechanically
damaged. The discharge voltage curve indicates a memory effect, but this is very low
compared to Ni-Cd alternatives.
Advantages:
• The first advantage which makes it ideal is its high energy density, which outperforms every battery type in many
comparisons.
• Secondly, the various sizes and low cost of producing the custom size battery make it easy to afford batteries for low budgets
projects.
• They can be easily recycled also can be reused more easily than any other batteries like Lead-Acid and Ni-Cd or Ni-MH,
which are either harmful to the environment or hard to recycle.
• They have a very low self-discharge rate, like 2% to 3% per month of the original C rating of the battery. Also, the adequate
rate of temperature range makes them able to use in almost all conditions (5 °C to 45 °C).
• Though the charging methods are the same as CC/CV, the charges are easy to afford same in the case of Li-Po battery but
these both need different charges as per their type.
• This battery is almost free from memory effect, which is the most important issue in cases of Drones and RC toys and
devices.
Disadvantages:
• The main disadvantage of these batteries is they need care and monitoring while charging as higher temperature during
charging may lead to leaking or even burning of battery causing a fire.
• The terminal of these batteries in AA or AAA size batteries needs to be either spot welded or first rubbed with sandpaper and
then soldered as same in the case of Li-Po batteries.
• You cannot keep the battery in the charged state as it will make the battery puffed up and lead to the destruction of the battery.
Even troubleshooting methods on YouTube didn’t work as it ultimately result in the loss of the capacity of the battery.
• They are not as good as Ni-Cd or Ni-MH in power tools which are portable as discharging current is less than compared to
other both types.
• You cannot fold or put excessive pressure on rectangular type packages as it may result in a leak or immediate fire, same as
for Li-Po batteries.
Li- ion battery pack:
• The diagram below illustrates the typical elements found in a rechargeable battery pack:
• Cells (Different form factors & chemistry types)
• BMS (Electronics to manage the battery)
• Connection System (Connector, pigtail, wires)
• Housing (Plastic, sheet metal, shrink, etc.)
• At the base of every Li-ion battery pack is the battery cell or cells. A pack can contain one
cell or many cells configured to achieve higher capacity or output voltage. This is achieved
by connecting cells in parallel or series, and we'll explore this much further in our next
blog. The cell is considered the “fuel tank” of the battery pack system, holding the energy
that will be released during discharge (when the engine is running) or replaced during a
charge cycle (when the tank is refilled at a gas station). However, there are other
components needed to utilize the energy stored in the cell.
• To safely use the energy stored in cells, the Li-ion battery pack needs a Battery
Management System (BMS). The BMS is the control system of the pack and can be
simple or complex, depending on the need of the battery pack and host application.
Returning to the car analogy, think of a battery pack's BMS like a car's control system. In a
car, the control system shuttles fuel from the fuel tank to the engine to be utilized in a
controlled and safe manner and notifies the user of any issues (i.e. low fuel). The BMS
performs a similar role by safely regulating the energy carried through the cells inside a
battery pack. It can also communicate information back to the end user (i.e. low battery
life).
• The connection system is what transforms a cell into a battery pack. Nickel strips are the
preferred method of connecting a battery cell to the control system. A thin strip of nickel is
capable of carrying high amounts of current, is flexible, durable, and can be attached to the
cell without the use of excessive heat. These strips provide a safe means of getting the
"fuel" out of the "fuel tank" to use it in a safe manner.
• Finally, all these components need to be packaged so that the battery pack can be installed
into a device. Once all components are properly placed and connected to one another, they
are sealed with either shrink wrap or a hard case. The housing ensures that the components
remain safely located and provides a clean package for the eventual use by an end user.
The type of housing depends on where the battery pack will be located inside the device
and if it is intended to be accessed by the end-user or a technician.
• Lithium battery pack technique refers to the processing, assembly and packaging of
lithium battery pack.
• The process of assembling lithium cells together is called PACK, which can be a single
battery or a
• lithium battery pack connected in series or parallel. The lithium battery pack usually
consists of a plastic
• case, PCM, cell, output electrode, bonding sheet, and other insulating tape, double-coating
tape, etc.
1) Lithium cell: The core of a finished battery
2) PCM (Protection Circuit Model) and BMS (Battery Management System): Protection
functions of over charge, over discharge, over current, short circuit, NTC intelligent
temperature control.
3) Plastic case: the supporting skeleton of the entire battery; Position and fix the PCM;
carry all other non-case parts and limit.
4) Terminal lead: It can provide a variety of terminal wire charging and discharging
interface for a variety of electronic products, energy storage products and backup
power.
5) Nickel sheet/bracket: Connection and fixing component of the cell.
• Calculations of battery pack for generating approx. 100 watt energy for approx. 2 hours.
• Single battery with 3.7 V and 2500mAh capacity.
• Using formulae (assuming 80% efficiency of the battery)

Efficiency  Battery voltage  Battery capacity 0.8  11.1  20

time(t)    1.776  2Hours
Total required power 100
• Therefore we need 24 cell of batteries with a pack of three (3.7 x 3 = 11.1) pairs in parallel and eight
(2500mAh x 8 = 20Ah) in series combination.
Lithium Battery Pack Assembly Process
1) Cell Capacity Grading: Capacity Difference≤30mAh After capacity grading, stay still for 48-
72h and then distribute.
2) Voltage Internal Impedance Sorting and Matching: Voltage Difference≤5mV Internal
Impedance Difference≤5mΩ 8 cells with similar voltage internal impedance are distributed
together.
3) Cell Spot Welding: The use of formed nickel strip eliminates the problems of spurious joint,
short circuit, low efficiency and uneven current distribution
4) Welded PCM: Make sure that the circuit board has no leakage components, and the
components have no defective welding.
5) Battery Insulation: Paste the fiber, silicone polyester tape for insulation.
6) Battery Pack Aging: For the quality of the battery, improve the stability, safety and service life
of the lithium battery.
7) PVC Shrink Film: Position the two ends after heat shrinking, then heat shrink the middle part.
Put PVC film in the middle. No whiten after stretching. No hole.
8) Finished Product Performance Test: Voltage：10.8～11.7V Internal Impedance：≤150mΩ
Charge-discharge and overcurrent performance test.
9) Battery Code-spurting: Code-spurting cannot be skewed, and it needs legible handwriting.
The major considerations in selecting a battery system are summarized below.
1) Battery Type: Primary, secondary, reserve or fuel cell system.
2) Battery Voltage: Nominal or operating voltage, maximum/minimum voltage limits, discharge
profile, voltage delay, start-up time.
3) Load Current & Profile: Constant current, constant resistance, or constant power; value of load
current, constant or variable load current.
4) Duty Cycle: Continuous or intermittent, schedule if cycle is intermittent.
5) Temperature Requirements: Operational temperature range.
6) Service Life: Length of time over which operation is required.
7) Physical Requirements: Size, shape, weight limitations.
8) Shelf Life: Allowable storage time.
9) Charge-Discharge Cycle: Discharge profile and charging efficiency.
10)Environmental Conditions: Atmospheric conditions including pressure and humidity, shock, vibration,
spin, acceleration environment compatibility.
11)Safety & Reliability: Permissible failure rates.
12)Maintenance: Ease of battery maintenance and replacement.
13)Cost: Initial and operating costs.
Comparative Analysis of Battery
Energy Energy Power Cycle Self-Discharge
Type
Efficiency Density(Wh/kg) Density(W/kg) life(Cycles) Rate
Lead-Acid 70-80 20-35 25 200-2000 Low
Ni-Cd 60-90 40-60 14-180 500-2000 Low
Ni-MH 50-80 60-80 220 <3000 High
Li-ion 70-85 100-200 360 500-2000 Medium
Li-polymer 70 200 250-1000 >1200 Medium
Flywheel (Steel) 95 May-30 1000 >20000 Very High
Flywheel (composite) 95 >50 5000 >20000 Very High

Energy
Energy Power Cycle Self-Discharge
Type Efficiency
Density(Wh/kg) Density(W/kg) life(Cycles) Rate
(%)
Lead-Acid 70-80 20-35 25 200-2000 Low

Ni-Cd 60-90 40-60 14-180 500-2000 Low

Ni-MH 50-80 60-80 220 <3000 High

Li-ion 70-85 100-200 360 500-2000 Medium

Li-polymer 70 200 250-1000 >1200 Medium

Flywheel
95 May-30 1000 >20000 Very High
(Steel)
Flywheel
(composite 95 >50 5000 >20000 Very High
)
NVH Analysis
NVH Analysis
Noise Factors:
• The main emphasis was on the reduction of noise induced by the asynchronous or synchronous
motor, gear, and inverter, and the improvement of sound quality. research found that resonance is
mainly induced by the second-order excitation associated with the driveline.
• Depending on the operational state of the engine, the source of NVH problems in the engine can
be divided into three categories: start process, idle process, stop process.
• NVH problems, which are frequently encountered during the starting process, are the result of
pump pressure, cranking reaction force, abrupt initial engine-torque, improper torque
compensation, and engine/damper resonant excitation.
• Problems during
• the idling process include battery charging, 1st engine-order combustion force, combustion-
pressure differences, and unstable combustion pressure in the single cylinder.
• During the stopping process of the engine, pump pressure, backward engine rotation, and
improper wheel-torque compensation cause intense vibration of the transmission system.
• The sources of the NVH problems in the electric motor can be divided into electromagnetic and
mechanical noise, aerodynamic noise, and vibration.
• Electromagnetic and mechanical noise include pulse-width modulation harmonics, excessive
electromagnetic harmonics, rotor/bearing/brush and slip ring/commutator friction.
• The aerodynamic noise consists of noise of the fan, the rotating rotor, and airflow noise. Sources
of vibration are the motor, rotor imbalance, bearings, and stator winding. The origin of NVH
problems in the powertrain includes the power-coupling device, clutch, and transmission.
Main sources of noise:
• the engine starting/stopping process for HEV.
• The frequent ignition of the engine to charge the battery whenever the SOC is below the
minimum.
• The induced vibration in The powertrain connects engine/motor and frame with elastic and
rigid components.
• Vibration and noise of the power-coupling device.
• The sources of motor noise can be categorized into three types: electromagnetic noise,
aerodynamic noise, and mechanical noise. Electromagnetic noise is either caused by the
PWM harmonic of the power supply control-unit, or by excessive electromagnetic harmonics
coming from the motor. Aerodynamic noise is generated by the fan, the rotor, and the airflow
effect, which is due to airflow when moving along the wind path. Mechanical noise is mainly
caused by the moving rotor, the bearing, and the motor’s brush and slip ring, or commutator
friction.
• The battery is frequently charged and discharged during operation, and various
electromagnetic interference (EMI) noise, such as differential noises, common mode noise,
and radiated noise, are transmitted through power-transmission lines.
Classification of Noise:
External Noise:
External noise is defined as the type of Noise which is general externally due
to communication system. External Noise are analysed qualitatively. Now, External Noise may
be classified as
1) Atmospheric Noise: Atmospheric Noise is also known as static noise which is the natural
source of disturbance caused by lightning, discharge in thunderstorm and the natural
disturbances occurring in the nature.
2) Industrial Noise: Sources of Industrial noise are auto-mobiles, aircraft, ignition of electric
motors and switching gear. The main cause of Industrial noise is High voltage wires. These
noises is generally produced by the discharge present in the operations.
3) Extra-terrestrial Noise: Extra-terrestrial Noise exist on the basis of their originating source.
They are subdivided into i) Solar Noise ii) Cosmic Noise.
Classification of Noise:
Internal Noise:
Internal Noise are the type of Noise which are generated internally or within the Communication System or in the receiver.
They may be treated qualitatively and can also be reduced or minimized by the proper designing of the system. Internal
Noises are classified as
1) Shot Noise: These Noise are generally arises in the active devices due to the random behaviour of Charge particles or
carries. In case of electron tube, shot Noise is produces due to the random emission of electron form cathodes.
2) Partition Noise: When a circuit is to divide in between two or more paths then the noise generated is known as Partition
noise. The reason for the generation is random fluctuation in the division.
3) Low- Frequency Noise: They are also known as FLICKER NOISE. These type of noise are generally observed at a
frequency range below few kHz. Power spectral density of these noise increases with the decrease in frequency. That
why the name is given Low- Frequency Noise.
4) High- Frequency Noise: These noises are also known TRANSIT- TIME Noise. They are observed in the semi-conductor
devices when the transit time of a charge carrier while crossing a junction is compared with the time period of that
signal.
5) Thermal Noise: Thermal Noise are random and often referred as White Noise or Johnson noise. Thermal noise are
generally observed in the resistor or the sensitive resistive components of a complex impedance due to the random and
rapid movement of molecules or atoms or electrons.
6) Burst noise: Burst noise consists of sudden step-like transitions between two or more discrete voltage and current levels,
as high as several hundred microvolts, at random and unpredictable times. Each shift in offset voltage or current lasts for
several milliseconds to seconds. It is also known a popcorn noise for the popping or crackling sounds it produces in
audio circuits.
7) Transit-time noise: If the time taken by the electrons to travel from emitter to collector in a transistor becomes
comparable to the period of the signal being amplified, that is, at frequencies above VHF and beyond, the transit-time
effect takes place and the noise input impedance of the transistor decreases. From the frequency at which this effect
becomes significant, it increases with frequency and quickly dominates other sources of noise.
Battery Packs design against Noise and Vibration exposure
Interface Definition Formed by
Mechanical Mechanical design features included Cell spacers. damping pads. gaskets.
for safety reasons. Valves.
Structural Members that provide required Case, cover, end-plates, tie rods,
protection and isolation. Members.
Thermal Case, cover, end-plates, tie rods, Coolant, fans, pumps, heat
Members exchangers
Electrical Transmits power from, and to, the Bus-ban, cables, contactors, fuse,
battery pack relays
Control Monitor and regulate the slate of Battery management system, various
battery pack Sensors
Support Vehicle body parts providing additional Axles, chassis, seals, vehicle floor
crash worthiness
Considerations in Battery Packs design against Noise and Vibration exposure
• For battery pack design it has been suggested that the battery temperature must be
maintained below 50°C for safe operation.
• The vibration frequencies of the battery pack should also he suppressed to avoid resonance
at typical natural frequencies of the vehicle suspension system and sprung mass from 0 to 7
Hz, the vehicle powertrain. i.e. driveline and gearbox, from 7 to 20 Hz, and the vehicle
chassis system from 20 to 40 Hz.
• Marginal deviations from the designed boundary can compromise the cycle life of the
battery pack.
• It can also set in motion an uncontrolled chain of exothermic reactions resulting in the
release of smoke or toxic gas and the development of high pressure events leading to
premature failure, fire and explosions.
• These marginal deviations can be caused by excessive heat build-up or physical abuse of
battery packs that includes puncturing or crushing the packs.
• A reliable battery packaging design should address issues relating to thermal stability,
vibration isolation and impact resistance at micro as well as macro level.
• Further, it should minimize thermal and mechanical interactions between different units of
the battery pack at each level, i.e. at cell and module level, thus reducing the probability of
failure of the battery pack itself design elements that can be optimized readily to achieve the
required level of protection without which impact on available resources are called control
factors.
• Some of the most critical control factors of an EV battery pack are: battery cells and cell
spacer type. number and location of gas exhaust nozzles, battery cooling system, and
insulation coating thickness.
• battery cell type has a significant influence of design of the battery packs. For example, it
has been found that packing density of a battery Pack with 18650 type cells is 114 times
more than that of a pack comprising large prismatic cells.
• Moreover, the packing density of a pouch cell is approximately 2 times lesser than that of a
prismatic cell of similar nominal capacity mainly because of its smaller thickness and large
surface area. It is therefore relatively easier to improve volumetric efficiency of the battery
pack by packaging large quantities of smaller cylindrical cells in the available space than to
use large prismatic or pouch cells.
• Compactness of packaging design also has an appreciable impact on thermal performance of
the battery pack. Research shows that increasing the cell-to-cell spacing for a battery pack
from 1 mm to 10 mm can lead to a loss of approximately 1°C in the steady state cell core
temperature, for all the three physical formats. According to NASA Battery Safety
Requirements Document (JSC 20793 Rev C). cell spacing is more critical for pack designs
employing battery cells of gravimetric energy density greater than 80 Wh/kg.
• It has further been ascertained that to alleviate cell-to-cell heat propagation in the instance of
a single cell failure or a thermal runaway event, a minimum spacing of 2 mm is required for
cylindrical cell formats.
• In addition, a physical harrier between neighboring cells is required for the same reasons in
battery packs that employ cell formats with side vents. Other important design requirements
are specified by various international standards.
Structural Stability:
• In the absence of adequate compressive forces needed to maintain uniform contact,
delamination of electrode layers occurs in pouch cell prismatic cells, which affects their
performance and reliability. Delamination of the electrode layers can be avoided through
usage of external structures that may include either hard plates stacked on each side of the
battery cell or clamps made of thread rods. Although the stacking plate method provides
significant advantage during manual assembly of battery packs, it is more expensive on a
mass production basis. Also, holding clamps may make the pouch cells more vulnerable to
mishandling during assembly process and to localized stress development due to unbalanced
clamping force.
• The solid structure created through metallic or rigid plastic casings typically used for the
prismatic and the cylindrical battery cells prevents foreign objects such as nails from
penetrating the electrochemical system. The metallic casings provide a greater degree of
tolerance to pressures generated inside the battery cell because of gas generation and venting;
a safety feature absent in pouch cells owing to their soft packaging. Main structural issue
with the prismatic cells is that their corners can be left vacant due to elliptical windings. It
results in uneven pressure distribution in electrodes but the problem can be alleviated by
filling vacant corners with solid material.
Comparison of structural characteristics of different types of battery cells
•.
Modal Analysis /Mode Shapes of in battery analysis
• The special initial displacements of a system that cause it to vibrate harmonically are called
`mode shapes' for the system. If a system has several natural frequencies, there is a
corresponding mode of vibration for each natural frequency.
• A mode shape is a deflection pattern related to a particular natural frequency and represents
the relative displacement of all parts of a structure for that particular mode.
• The battery pack in electric vehicles is subjected to road-induced vibration and this vibration
is one of the potential causes of battery pack failure, especially once the road-induced
frequency is close to the natural frequency of the battery when resonance occurs in the cells.
If resonance occurs, it may cause notable structural damage and deformation of cells in the
battery pack.
• The laser scanning vibrometer is used for modal analysis with frequency response functions
(FRF).
• Procedure of mode shape analysis of li-ion battery pack.
1) The un-damped free vibration equation for the system is, MX + SX = 0.
2) natural mode of vibration, the displacement of each mode is calculated by:
Xi = Xi,m × sin(wt + Øi)
• where, M is the mass matrix, X is the mass acceleration vectors, S is the stiffness matrix, and
X is the displacement vectors of the modes. w and Øi are the angular frequency and phase
angle of the ith mode. Xi is the matrix of the displacement of the modes, and Xi,m is the vector
of maximum values. If the displacement field of the given structure is harmonic, the Eigen
frequency can be derived. Dictating equations in the study are in terms of the excitation load.

• where, r is the density of the material, w is the angular frequency of the excitation load, and
u is the harmonic response from the structure. The Eigenvalue λ and the Eigen frequencies
f are calculated using Equation

• LIB is held on the shaker and the baseplate is designed in a way to accommodate the
geometry of the battery. the baseplate aims to provide rigid support to the battery and hold
the battery firmly. The baseplate is designed such that the battery fits in easily and the fixture
including the battery does not exceed the weight-bearing limit of the shaker. The material
used for the baseplate is 6061 Aluminum and its geometry.
• The baseplate is mounted on the shaker using M6 screws to the center of the shaker and is
torqued down with 45 lb/in. Then, the battery is fixed on that plate with clips. To perform
sinusoidal frequency sweeps, a 110 lb MB RED dynamic shaker is used. A signal generator is
used to create input variables.
• Due to restrictions of weight that the dynamic shaker aperture load is 12 lb and the maximum
weight of the apparatus that the aperture arm of the shaker can handle is 11 lb, the weight of the
fixture and apparatus including the battery is determined to be 10 lb. At the test of the structure
mounted aperture arm, the dynamic shaker delivers low noise motion.
• The casing material used all around the flexures to hold the internal components is stainless steel.
Using a set of ultra-flexible multi-strand wire, coil currents are conducted to the coil from which
the shaker receives the signal and responds accordingly.
• The cooling system is provided with a constant field and eliminates the need for a power source,
to reduce the resistive losses of the electromagnet from coil overheating and abate the breakdown
of the coil insulation. The baseplate is then installed onto the aperture arm of the shaker.
• The velocity of the battery is directly measured with laser scanner and the velocity data is
converted to FRF calculations using integrated laser vibrometer. For conducting calculations of
the frequency response function, there is a built-in accelerometer that is attached to the surface of
the dynamic shaker.
• Experimental set up
• Experimental set up
For different meshing, boundary conditions and converging criteria mode shapes are,
Pouch LIB mode shapes for boundary condition 1 shown in Figure (a) mode shape 1–first
bending, (b) mode shape 2–first torsion, (c) mode shape 3–second torsion, (d) mode shape 4–
second bending, (e) mode shape 5–third bending, (f) mode shape 6–third torsion.,
LIB mode shapes in boundary condition 2 shown in Figure. (a) mode shape 1–first bending, (b)
mode shape 2–first torsion, (c) mode shape 3–second torsion, (d) mode shape 4–second
bending, (e) mode shape 5–third bending, (f) mode shape 6–third torsion.
Definition of mode shapes from multiple frequency response functions
frequency response (magnitude plots) for each impact location for different cells.
Component Sizing And Integration Tradeoffs Performance
• Component sizing : Component sizing is essential to meet the performance
requirements with the optimum resources and at the same time prevents unwanted
wastage of energy resources and losses.
• Modes of sizing
 In backward simulation, the desired vehicle speed input goes from the vehicle
dynamic model back to the engine to determine how each component should
perform during the drive cycle operation.
 A driver model sends an acceleration or brake signal to different power-train and
component controllers (e.g., throttle for engine, displacement for clutch, gear
number for transmission, or mechanical braking for wheels) in order to follow the
desired vehicle speed trace
Backward modeling approach
Forward modeling approach
ELEMENTS OF VEHICLE DYNAMICS
• In vehicle dynamics, the vehicle body (sprung mass), the suspension component (spring and
damper) and tire (unsprung mass) are essential parts of the system.
• Factors affecting vehicle dynamics
1) Drivetrain and braking
2) Suspension and steering
3) Distribution of mass
4) Aerodynamics
5) Tires
• Analysis and Simulation considering spring mass system and using software like ADAMS,
Modelica, CARsim, Simulink etc.
DYNAMICS OF THE MOTOR VEHICLE:
• It is a combine study of interaction between driver, vehicle, road and environment.
• It mainly deals with, the improvement of active safety and driving comfort and the reduction
of road destruction.
• The acceleration of the vehicle depends upon the power delivered by the propulsion unit,
road conditions, aerodynamics shape and mass of the vehicle.
• General description of the vehicle movement like tractive force, rolling resistance,
aerodynamic drag and uphill (grading and acceleration) resistance.
• Longitudinal vehicle dynamics, Forces and motions in longitudinal direction, smooth road
surface Predicting top speed, acceleration and braking performances, gradeability, fuel
consumption...
• Lateral vehicle dynamics, Forces and motions mainly in lateral direction Predicting
cornering performances, handling, stability..
• Vertical vehicle dynamics, Forces and motions mainly in vertical direction Ride, vibration
behavior, tier/road contact...
Forces acting on the vehicle
• Gravity effects
• Aerodynamic forces
• Tyre-road interaction
• Tyre behavior (longitudinal and side slip)
• The dynamic equation of vehicle motion along the longitudinal direction
Performance parameters
• Acceleration
• Top speed
• Gradeability
• Breaking performances
• Adhesion, Dynamic wheel radius and slip
Driver Environment

Load

Vehicle
• Motorcycles
• passenger cars
• busses
• Trucks
• agricultural tractors, passenger cars with trailer, truck trailer / semitrailer, road trains.
VEHICLE COORDINATE SYSTEM
Coordinate Systems in Automated Driving Toolbox
• World: A fixed universal coordinate system in which all vehicles and their sensors are placed.
• Vehicle: Anchored to the ego vehicle. Typically, the vehicle coordinate system is placed on the ground
right below the midpoint of the rear axle.
• Sensor: Specific to a particular sensor, such as a camera or a radar.
• Spatial: Specific to an image captured by a camera. Locations in spatial coordinates are expressed in
units of pixels.
• Pattern: A checkerboard pattern coordinate system, typically used to calibrate camera sensors.
World Coordinate System
• All vehicles, sensors, and their related coordinate systems are placed in the world coordinate system.
• A world coordinate system is important in global path planning, localization, mapping, and driving
scenario simulation.
• Automated Driving Toolbox uses the right-handed Cartesian world coordinate system defined in ISO
8855, where the Z-axis points up from the ground. Units are in meters.
Vehicle Coordinate System
The vehicle coordinate system (XV, YV, ZV) used by Automated Driving Toolbox is anchored to the ego vehicle.
The term ego vehicle refers to the vehicle that contains the sensors that perceive the environment around the
vehicle.
• The XV axis points forward from the vehicle.
• The YV axis points to the left, as viewed when facing forward.
• The ZV axis points up from the ground to maintain the right-handed coordinate system.
The vehicle coordinate system follows the ISO 8855 convention for rotation. Each axis is positive in the clockwise
direction, when looking in the positive direction of that axis.
In most Automated Driving Toolbox functionality, such as cuboid driving scenario simulations and visual
perception algorithms, the origin of the vehicle coordinate system is on the ground, below the midpoint of the rear
axle. In 3D driving scenario simulations, the origin is on ground, below the longitudinal and lateral center of the
vehicle.
Locations in the vehicle coordinate system are expressed in world units, typically meters.
Values returned by individual sensors are transformed into the vehicle coordinate system so that they can be placed
in a unified frame of reference.
For global path planning, localization, mapping, and driving scenario simulation, the state of the vehicle can be
described using the pose of the vehicle. The steering angle of the vehicle is positive in the counterclockwise
direction.
Sensor Coordinate System
An automated driving system can contain sensors located anywhere on or in the vehicle.
The location of each sensor contains an origin of its coordinate system. A camera is one type
of sensor used often in an automated driving system. Points represented in a camera
coordinate system are described with the origin located at the optical center of the camera.
• The yaw, pitch, and roll angles of sensors follow an ISO convention. These angles have
positive clockwise directions when looking in the positive direction of the Z-, Y-, and X-axes,
respectively.
Spatial Coordinate System
Spatial coordinates enable you to specify a location in an image with greater granularity than
pixel coordinates. In the pixel coordinate system, a pixel is treated as a discrete unit, uniquely
identified by an integer row and column pair, such as (3,4). In the spatial coordinate system,
locations in an image are represented in terms of partial pixels, such as (3.3,4.7).
Pattern Coordinate System
To estimate the parameters of a monocular camera sensor, a common technique is to calibrate
the camera using multiple images of a calibration pattern, such as a checkerboard. In the
pattern coordinate system, (XP, YP), the XP-axis points to the right and the YP-axis points
down. The checkerboard origin is the bottom-right corner of the top-left square of the
checkerboard. Each checkerboard corner represents another point in the coordinate system. For
example, the corner to the right of the origin is (1,0) and the corner below the origin is (0,1).
• Earth fixed coordinate system
Based on earth fixed axis system in which origin is fixed in the ground plane. This axis
system is fixed in the initial reference frame where X and Y are parellal to the ground plane
and z points upwards aligns with gravitational vector.
• Vehicle coordinate system
Based on vehicle axis system with origin located at the vehicle reference point. It is fixed in
the reference frame of the vehicle sprung mass so that x axis is horizontal and forwards with
the vehicle at rest. It is parellal to the vehicle longitudinal plane of symmetry and the Y axis
is perpendicular to the vehicles longitudinal plane of symmetry and points to the left with
the Z axis pointing upward.
WHEEL ANGLES
Primary angles
The primary angles are the basic angle alignment of the wheels relative to each other and to the car
body. These adjustments are the camber, caster and toe. On some cars, not all of these can be adjusted
on every wheel.
These three parameters can be further categorized into front and rear (with no caster on the rear,
typically not being steered wheels). In summary, the parameters are:
• Front: Caster (left & right)
• Front: Camber (left & right)
• Front: Toe (left, right & total)
• Rear: Camber (left & right)
• Rear: Toe (left, right & total)
4-Wheel Caster Steer (all swivels) 4-Wheel Diamond Pattern (all rigid) 4-Wheel Caster Steer (2 swivels, 2 rigid)
This cart configuration can be maneuvered in any This tilt-type cart configuration rotates or pivots on the center This cart configuration is the most popular. It is easily turned
direction. Ideal for confined areas, but needs swivel wheels. This is the lowest cost cart configuration and is suitable or pushed straight and it also trails well.
lock for traveling long distances in a straight line. for light loads. This design cannot be pushed sideways.

4-Wheel Diamond Pattern (2 swivels, 2 rigid) Wagon (fifth wheel steer)

This cart configuration is highly maneuverable and will This trailer configuration features large axle mounted wheels 6-Wheel Tilt or Non-Tilt (4 swivel, 2 rigid)
rotate in its own length. for heavy loads. This is usually powered drawn. This cart configuration is recommended for heavy loads and
extra long trucks. It turns in its own length. The casters on the
corners provide stability.
SECONDARY ANGLES
The secondary angles include numerous other adjustments, such as:
• SAI (Steering Axis Inclination) (left & right)
• Included angle (left & right)
• Toe out on turns (left & right)
• Maximum Turns (left & right)
• Toe curve change (left & right)
• Track width difference
• Wheelbase difference
• Front ride height (left & right)
• Rear ride height (left & right)
• Frame angle
• Setback (front & rear)
Cooling System and Thermal Management
Effect of Temperature on battery
Battery Thermal Management System (BTMS)
• EV battery pack thermal management is needed for three basic reasons:
• To ensure the pack operates in the desired temperature range for optimum performance and working life. A typical temperature
range is 15-35°C.
• To reduce uneven temperature distribution in the cells. Temperature differences should be less than 3-4C°.
• To eliminate potential hazards related to uncontrolled temperature, e.g. thermal runaway.
• The electric vehicle has a battery management system (BMS) to provide essential information such as:
• Thermal Protection
• Over and Under voltage protection
• Over-current Protection
• Prolong battery life
• Cell Balancing
• SoC and SoH calculation
• Communication with all battery components
• Data acquisition and analysis
• The high battery temperature leads to poor performance, short lifetime, and risk of blasting. Therefore, a BTMS is essential for
all battery modules.
• The main purpose of a BTMS is to maintain the battery system in the optimum temperature range and keep uniform temperature
variation in the battery modules
• Other factors for battery selection are weight, size, reliability, and the cost
• The following figure shows the most used thermal management techniques for battery module
Different Battery Cooling Methods Used in BTMS
• Batteries work based on the principle of a voltage differential, and at high temperatures, the
electrons inside become excited which decreases the difference in voltage between the two sides of
the battery.
• Because batteries are only manufactured to work between certain temperature extremes, they will
stop working if there is no cooling system to keep it in a working range.
• Cooling systems need to be able to keep the battery pack in the temperature range of about 20-40
degrees Celsius, as well as keep the temperature difference within the battery pack to a minimum
(no more than 5 degrees Celsius).
• Potential thermal stability issues, such as capacity degradation, thermal runaway, and fire
explosion, could occur if the battery overheats or if there is non-uniform temperature distribution
in the battery pack.
• In the face of life-threatening safety issues, innovation is continually happening in the electric
vehicle industry to improve the battery cooling system.
• There Are A Few Options To Cool An Electric Car Battery—with Phase Change Material, Fins,
Air, Or A Liquid Coolant.
• The Determining Features Of An Electric Vehicle Battery Cooling System Are Temperature Range
And Uniformity, Energy Efficiency, Size, Weight, And Ease Of Usage (I.E. Implementation,
Maintenance).
• Phase change material absorbs heat energy by changing state from solid to liquid. While
changing phase, the material can absorb large amounts of heat with little change in
temperature. Phase change material cooling systems can meet the cooling requirements of
the battery pack, however, the volume change that occurs during a phase change restricts
its application. Also, phase change material can only absorb heat generated, not transfer it
away, which means that it won’t be able to reduce overall temperature as well as other
systems. Although not favorable for use in vehicles, phase change materials can be useful
for improving thermal performance in buildings by reducing internal temperature
fluctuations and reducing peak cooling loads.
• Cooling fins increase surface area to increase the rate of heat transfer. Heat is transferred
from the battery pack to the fin through conduction, and from the fin to the air through
convection. Fins have high thermal conductivity and can achieve cooling goals, but they
add a lot of additional weight to the pack. The use of fins has found a lot of success in
electronics, and traditionally they have been used as an additional cooling system on
internal combustion engine vehicles. Using fins to cool the electric car battery has fallen
out of favor since the additional weight of the fins outweighs the cooling benefits.
• Air cooling uses the principle of convection to transfer heat away from the battery pack.
As air runs over the surface, it will carry away the heat emitted by the pack. Air cooling is
simple and easy, but not very efficient and relatively crude compared to liquid cooling. Air
cooling is used in earlier versions of electric cars, such as the Nissan Leaf. As electric cars
are now being used more commonly, safety issues have arisen with purely air-cooled
battery packs, particularly in hot climates. Other car manufacturers, such as Tesla, insist
that liquid cooling is the safest method.
• Liquid coolants have higher heat conductivity and heat capacity (ability to store heat in the
form of energy in its bonds) than air, and therefore performs very effectively and own
advantages like compact structure and ease of arrangement. Out of these options, liquid
coolants will deliver the best performance for maintaining a battery pack in the correct
temperature range and uniformity. Liquid cooling systems have their own share of safety
issues related to leaking and disposal, as glycol can be dangerous for the environment if
handled improperly. These systems are currently used by Tesla, Jaguar, and BMW, to name
a few.
• In Liquid Cooling Systems, There Is Another Division Between Direct And Indirect
Cooling—whether The Cells Are Submerged In The Liquid Or If The Liquid Is Pumped
Through Pipes.
• Direct cooling systems place the battery cells in direct contact with the coolant liquid.
These thermal management schemes are currently in the research and development stage,
with no cars on the market using this system. Direct cooling is more difficult to achieve,
due to the fact that a new type of coolant is required. Because the battery is in contact with
the liquid, the coolant needs to have low to no conductivity.
• Indirect cooling systems are similar to ICE cooling systems in that both circulate liquid
coolant through a series of metal pipes. However, the construction of the cooling system
will look much different in electric vehicles. The structure of the cooling system that
achieves maximum temperature uniformity is dependent on the shape of the battery pack
and will look different for each car manufacturer.
Future Of EV Battery Cooling
• Since electric vehicles have become so widely used, there is a high demand for longer
battery life and higher power output.
• To achieve this, the battery thermal management systems will need to be able to transfer
heat away from the battery pack as they are charged and discharged at higher rates.
• The heat generated as the battery is used can pose safety threats to the passengers.
• Due to the high stress and temperatures generated by the batteries, there is even higher
importance on having the correct coolant and additive package.
• While companies such as Tesla, BMW, and LG Chem can use a traditional liquid coolant
for their indirect cooling systems, continued research and development will need to be
done on battery packs and coolants to advance electric vehicle safety.
 Assignment 2
1. Define energy storages, explain with its classifications?
2. List and explain battery Energy Storage System Components?
3. Explain the constructional details of li-ion battery with its advantages, disadvantages and
applications?
4. Explain the constructional details of Ni-Cd battery with its advantages, disadvantages and
applications?
5. Explain the constructional details of lead acid battery with its advantages, disadvantages
and applications?
6. List and explain the components of li-ion battery pack?
7. List and explain the steps involved in formation of li-ion battery pack?
8. What are the major considerations in selecting a battery system?
9. Compare lead acid, nickel and lithium batteries on basis of cost, energy efficiency,
temperature performance, weight and life cycle?
10. Explain NVH analysis with its importance in electric vehicles?
11. Explain noise factors with its main sources and classification?
12. Explain Battery Packs design and considerations against Noise and Vibration exposure?
13. Compare of structural characteristics of different types of battery cells?
14. Explain the Modal Analysis /Mode Shapes of in battery analysis with its experimental
steps?
15. Explain vehicle dynamics with its elements and affecting factors?
16. Explain vehicle coordinate system with suitable sketch?
17. Explain briefly Cooling System and Thermal Management?
18. Explain Battery Thermal Management System?
19. Explain different types of battery cooling with its significance?
20. Compare types of battery cooling with its advantages and disadvantages?