BLDC Motors application
in Railway and Metro
Course: SEMINAR
Course code:19EE702
Name: Kiran U
Usn:4NM20EE411
Sec: A
1
Department of Electrical and Electronics Engineering
13/10/22
Contents
1.INTRODUCTION
2.CONSTRUCTION
3.WORKING
4.ADVANTAGES/DISADVANTAGES
5.APPLICATION
2
Department of Electrical and Electronics Engineering
13/10/22
INTRODUCTION
• Conventional dc motors are highly efficient and their characteristics make them suitable for
use as servomotors.
• However, their only drawback is that they need a commutator and brushes which are
subject to wear and require maintenance.
• When the functions of commutator And brushes were implemented by solid-state
Switches, maintenance-free motors were realized.
• These motors are now known as brushless DC Motors.
• Classical DC motors are no doubt good and simple but inefficient same ways.
• Although DC motors possess good control characteristics and ruggedness, their
performance And applications are inhibited due to sparking and communication problem’s.
The permanent magnet Brushless DC Motors is able to overcome the limitations
3
Department of Electrical and Electronics Engineering
13/10/22
CONSTRUCTION
•Brushless DC electric motors also known as electronically commutated motors (ECMs,EC motors).
Primary efficiency is a most important feature for BLDC motors. Because the rotor is the sole
bearer of the magnets and it doesn’t require any power. i.e. no connections, no commutator and
no brushes. In place of these, the motor employs control circuitry. To detect where the rotor is
at certain times, BLDC motors employ along with controllers, rotary encoders or a Hall sensor.
4
Department of Electrical and Electronics Engineering
13/10/22
BLOCK DIAGRAM
5
Department of Electrical and Electronics Engineering
13/10/22
CONSTRUCTION OF BLDC
• The Construction of modern brushless motors is very Similar to the ac
motor, known as the permanent Magnet synchronous motor. Illustrates
the structure Of a typical Three- phase brushless DC motor.
• The stator windings are similar to those in a polyphone Ac motor and
the rotor is composed of one or more Permanent magnets.
• Brushless DC Motors are Different from ac synchronous motors in that
the Former incorporates some Means to detect the rotor Position (or
magnetic poles) to produce signals to Control the Electronic switches.
• The most common Position/pole sensor is the Hall element, but some
are optical sensors.
6
Department of Electrical and Electronics Engineering
13/10/22
Continued
In this motor, the permanent magnets attach to the rotor. The current-carrying
conductors or armature windings are located on the stator. They use electrical
commutation to convert electrical energy into mechanical energy
The main design difference between a brushed and brushless motors is the replacement
of mechanical commutator with an electric switch circuit. A BLDC Motor is a type of
synchronous motor in the sense that the magnetic field generated by the stator and the
rotor revolve at the same frequency. Brushless motor does not have any current carrying
commutators. The field inside a brushless motor is switched through an amplifier which is
triggered by the commutating device like an optical encoder.
7
Department of Electrical and Electronics Engineering
13/10/22
Continued
•The layout of a DC brushless motor can vary depending on whether it is in “Out runner” style or “Inrunner” style.
Outrunner – The field magnet is a drum rotor which rotates
around the stator. This style is
preferred for applications that require high torque and
where high rpm isn’t a requirement.
•In runner – The stator is a fixed drum in which the field magnet rotates. This motor is known for producing less torque than the out
runner style, but is capable of spinning at very high rpm.
•The main design difference between a brushed and brushless motors is the replacement of mechanical commutator with an electric
switch circuit. Keeping that in mind, a BLDC Motor is a type of synchronous motor in the sense that the magnetic field generated by
the stator and the rotor revolve at the same frequency.
8
Department of Electrical and Electronics Engineering
13/10/22
Continued.
•Stator:-
•The structure of the stator of a BLDC Motor is similar to that of an induction motor. It is
made up of stacked steel laminations with axially cut slots for winding. The winding in
BLDC are slightly different than that of the traditional induction motor.
Generally, most BLDC motors consists of three stator
windings that are connected in star or ‘Y’ fashion
(without a neutral point). Additionally, based on the coil
interconnections, the stator windings are further
divided into Trapezoidal and Sinusoidal Motors.
9
Department of Electrical and Electronics Engineering
13/10/22
Continued.
Rotor:-
The rotor part of the BLDC Motor is made up of permanent magnets (usually, rare earth alloy
magnets like Neodymium (Nd), Samarium Cobalt (SmCo) and alloy of Neodymium, Ferrite and Boron
(NdFeB)).
Based on the application, the number of poles can vary between two and eight with North (N) and
South (S) poles placed alternately. The following image shows three different arrangements of the
poles. In the first case, the magnets are placed on the outer periphery of the rotor.
10
Department of Electrical and Electronics Engineering
13/10/22
Continued.
The second configuration is called magnetic-embedded rotor, where rectangular
permanent magnets are embedded into the core of the rotor. In the third case, the
magnets are inserted into the iron core of the rotor.
Position Sensors (Hall Sensors):-
Since there are no brushes in a BLDC Motor, the commutation is controlled electronically.
In order to rotate the motor, the windings of the stator must be energized in a sequence
and the position of the rotor (i.e. the North and South poles of the rotor) must be known
to precisely energize a particular set of stator windings.
A Position Sensor, which is usually a Hall Sensor (that works on the principle of Hall Effect)
is generally used to detect the position of the rotor and transform it into an electrical
signal. Most BLDC Motors use three Hall Sensors that are embedded into the stator to
sense the rotor’s position.
11
Department of Electrical and Electronics Engineering
13/10/22
Driving Brushless DC motors
If stator and rotor are essential parts of a BLDC Motor that are integral to it, then the driving electronics are
equally essential. Block diagram of a typical Brushless DC Motor control or drive system is shown in the
following image.
12
Department of Electrical and Electronics Engineering
13/10/22
Continued
This drive circuitry is often known as Electronic Speed Controller System or simply an
ESC. One common setup is called the Full Bridge Drive Circuit. It consists of an MCU
with PWM outputs, six MOSFETS for the three phases of the stator windings, feedback
from the Hall sensors and some power supply related components.
The MCU can be programmed to appropriately switch the MOSFETS based on the data from the
Hall Sensors.
13
Department of Electrical and Electronics Engineering
13/10/22
BLDC MOTOR APPLICATION
• 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.
• Under high mechanical loads, Brushless motors and high-quality brushed motors Are comparable in
efficiency.
• Consumer: Hard Drives, CD/DVD Drives, PC Cooling Fans, toys, RC airplanes, Air conditioners
• Medical: Artificial heart, Microscopes, centrifuges, Arthroscopic surgical Tools, Dental surgical tools and
Organ transport Pump system.
• Vehicles: electronic power steering personal electric vehicles
• Airplanes: an electric self Launching sailplane, flies with a 42kW DC/DC
• Brushless motor and Li-lon batteries and can climb Up to 3000m with fully charged cells.
14
Department of Electrical and Electronics Engineering
13/10/22
Few of their main benifits
• Fantastic speed control DC motors are Known for their great speed control, Offering great
precision and safety that Trains require.
• Broad speed variation can Be achieved by changing the armature or Field voltage.
• Smooth operation: DC motors can work In accordance with many applications,
Including trains, to provide the necessary Speed and power required.
• Being a vital Method of transport, trains must be able To start and stop efficiently to
both save
• Time and in case of danger.
• High torque: As a train is considered a Heavy load, DC motors are well suited Due to
their high torque.
• This means that The motor can drive a consistent level of Power over longer periods of
time, ideal For trains that operate over 12 hours per Day.
15
Department of Electrical and Electronics Engineering
13/10/22
Advantages
• Increased Reliability & Efficiency
• Longer Life
• Elimination of Sparks from Commutator
• Reduced Friction
• Faster Rate of Voltage & Current
• Brushless DC motor does not have any carbon brushes, which reduces frequent replacement requirements of brushes
and maintenance costs.
• Brushless DC motors are available in small compact sizes and also provide high torque to weight ratio making it suitable
for many robotics and medical applications involving robotic arms and robotic legs.
• Brushless DC motor produces comparatively low operating noise as compared to other motors of the same ratings. As
in other motors, there is continuous contact of brushes resulting in noise and sparking during contact. Therefore,
brushless DC motors are given preference where electrical noise needs to be avoided.
• As traditional commutation based on mechanical setup is replaced by the modern electronic commutation system
resulting in more control and fewer chances of failure due to previously discussed reasons of wear and tear.
• Unlike other motors, brushless DC motor has low no-load current making it suitable to run it at low or no load.
16
Department of Electrical and Electronics Engineering
13/10/22
Disadvantages
• Requires Complex Drive Circuitry
• Requires additional Sensors
• Higher Cost
• Some designs require manual labor (Hand wound stator Coils)
• The cost of a brushless DC motor is comparatively higher as compared to brushed DC motor and the
electronic controller also increases the cost of overall setup, as in a traditional motor, low-cost
mechanical commutation setup involving brushes is used.
• When brushless DC motor is operated at low speed, slight vibrations occur during low-speed
rotation. However, vibrations reduce at high speed.
Brushed DC motors are easy to operate having simple wiring as thositive terminal is connected to
positive and negative terminal is connected to negative wire and motor starts to rotate. However, in
the case of brushless DC motor, wiring and operation of the motor are not that simple due to the
involvement of electronic control and its link to all the electromagnets.
17
Department of Electrical and Electronics Engineering
13/10/22
Limitations of BLDC Motors
• These motors are costly
• Electronic controller required control this motor is expensive
• Requires complex drive circuitry
• Need of additional sensors
18
Department of Electrical and Electronics Engineering
13/10/22
Conclusion
• Permanent magnet Brushless DC motors are generated by virtually inverting
• The stator and rotor of PM DC Motors.
• This motors are actually fed by rectangular AC Waveform.
• This advantages is the removal of brushes, leading to eliminate many problems
Associated with brushes.
• Another advantages is The ability to produce a large torque because of the
Rectangular Interaction between current and flux.
19
Department of Electrical and Electronics Engineering
13/10/22
Thank You
20
Department of Electrical and Electronics Engineering
13/10/22
