ME4336 Number of printed pages: 02

ELECTRIC VEHICLE TECHNOLOGY

Mid Semester Examination (Spring) 2023-24
National Institute of Technology Rourkela
Time: 2 Hrs Full Mark: 30
(Numerals in bracket indicate marks; Assume suitably if required and state them clearly)
Answer to all parts of a question should be written together. Section A should be answered
together, preferably in the order of the questions
Section A
(Answer to the point and in short; write answer to all bits at one place)
1. What is hotel load? [2]
2. Write the name of six simple machines. [2]
3. Explain the system architecture of Fuel Cell Electric Vehicle (FCEV) with schematic diagram. State
its main components. Write name of one commercially available FCEV. [2]
4. State eight different benefits of Electric Vehicles (EVs). [2]
5. What is FAME-II. [2]

Section B
6. What is UDDS? The screenshot for UDDS data file for a particular journey carried out for one
minute (at an interval of 5 sec each) in an EV is given in Fig. 1 along with the corresponding
elevation based on GPS measurements (Fig. 2). Tabulate and plot the variation of (i) acceleration
with time (ii) slope of the road at each time instant (iii) power requirement at each instant of time
with and without considering slope of the road. Given: density of air 1.25 kg/m3, Cd = 0.25, EV
frontal area 2.67 m2, EV weight 1465 kg, driver weight 52 kg, tyre condition good and the EV is
accelerating at 1.35 m/s2. Assume suitably if required and state them clearly with proper justification.
[5]

Fig. 1 Fig. 2 Fig. 3

7. (a) Calculate the efficiency of the EV for which the cumulative energy consumption is given in Fig.
3. If the battery capacity of the EV is 85 kWh, calculate the range of the EV for full charge. [2]
(b) state and explain (i) Lorentz Force Law, (ii) Biot-Savart’s Law, and (iii) Faraday’s Law [3]
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 Section C: Answer any ONE from the following [10 marks]
8. (a) A brushless AC motor with 6 pole pairs is operating at an AC frequency of 55 Hz. What is the
synchronous speed of the motor in RPM? [1]
(b) Why do magnets stick to magnetic material? [1]
(c) Define slip of rotor. If the slip of the rotor of a brushless AC motor with 4 pole pairs which is
operating at an AC frequency of 50 HZ is 5%. Calculate the rotational speed of the rotor in rpm? [2]
(d) For a motor which uses a rectangular loop (of 10 turns) of radius of rotation r = 5 cm, coil length
ℓ= 14 cm, the motor losses is given by losses  k c T 2  k i   k w 3  C where T is motor torque, kc =
0.35, ki = 0.012, kw = 55×10-6, C = 5.6×102. Calculate the motor loss for a motor speed of 1800 rpm.
Given motor constant Km = 0.2, magnetic field B = 2 Tesla, rotor resistance Rr = 5 ohm. [2]
(e) For the Tesla model S, the weight of the EV is 1673 kg. Four friends take a ride of the EV whose
weight are 75 kg, 65 kg, 46 kg, and 62 kg. If the weight to power ratio under laboratory condition
(without any passenger in the EV) is reported to be 4.4 kg/kW. Calculate the time taken in sec to
accelerate the EV from 0 to 65 kmph (i) under laboratory condition (ii) on road while four friends
ride the EV together. [4]
(You have to answer to all the parts of Q8 together in your answer sheet)
9. Mr Harish decides to drive his EV next week from his residence at his hometown to a nearby hill
station which is at a distance of 15 KM. The hill station lies at an altitude of 4520 m above mean sea
level while the city where Mr Harish resides is at an altitude of 1310 m. The EV tyre condition is
observed to be average. (i) If the EV weight is 1345 kg and Mr Ram weights 56 kg, derive the power
equation assuming the road from Mr Harish’s residence to the hill station is straight and the slope of
the road gradually increases in the forward direction. Given: The EV manufacturer has reported the
EV frontal area 2. 43 m2, EV manufacturing date as Feb 2021 and the drag coefficient value on the
date of manufacturing is 0.25, which increases by 4 % for usage of the vehicle by a year compared to
previous year. The air density is function of the altitude which is given by ρ = 1.25 –
2.5×(altitude)×10-2 where the altitude is in kilometre and density is in kg/m3. Hint: Take average air
density value by considering average of maximum and minimum value along the drive. (ii) Calculate
total power requirement (kW), power requirement for rolling resistance, air resistance, hill climbing
along the trip to the hill station with increasing EV speed (km/hr) for the vehicle to be in rolling
motion with an acceleration of 0.65 m/s2. Plot the same on graph paper neatly (with proper scaling)
and find the EV speed at which power required to overcome air resistance exceeds rolling resistance
and hill climbing component. (iii) Tabulate the value of power requirements for rolling resistance, air
resistance, hill climbing, and accelerating the EV and their value in percentage of total power
requirement when the EV is running at a speed of 55/3 m/s. Assume suitably if required to solve this
problem and state them clearly with proper justification. [5+3+2]
*********************
2
 ME4336 Number of printed pages: 02

ELECTRIC VEHICLE TECHNOLOGY

End Semester Examination (Spring) 2023-24
National Institute of Technology Rourkela
Time: 3 Hrs Full Mark: 50
Answer to all parts of a question should be written together.
Section A (Answer all)
(Answer to the point and in short; write answer to all bits of this section at one place)
1. Explain the working of a heat pipe with schematic diagram. Write two applications of heat pipe other
than for battery thermal management. [1+1]
2. For a motor which uses a rectangular loop (of 10 turns) of radius of rotation r = 5 cm, coil length ℓ=
14 cm, the motor losses is given by losses  k c T 2  k i   k w 3  C where T is motor torque, kc =
0.35, ki = 0.012, kw = 55×10-6, C = 5.6×102. Calculate the motor loss for a motor speed of 1800 rpm.
Given motor constant Km = 0.2, magnetic field B = 2 Tesla, rotor resistance Rr = 5 ohm. [2]
3. What are the emissions associated with an EV. How we can reduce emission associated with an EV?
[1+1]
4. (a) What is duty cycle? (b) state and explain Lorentz Force Law [1+1]
5. State different forces acting on a rolling vehicle and write their mathematical forms [2]

Section B (Answer all)

6. What is the state of charge (SoC) and depth of discharge (DoD)? What is the relation between the
battery capacity, SoC and DoD? Estimating the state of charge of the battery is crucial to the
operation of an EV. Describe different methods to measure the charge remaining in a battery.
[2+1+2]
7. (a) For the Tesla model S, the weight of the EV is 1763 kg. Four friends take a ride of the EV whose
weight are 72 kg, 65 kg, 46 kg, and 58 kg. If the weight to power ratio under laboratory condition
(without any passenger in the EV) is reported to be 4.5 kg/kW. Calculate the time taken in sec to
accelerate the EV from 0 to 60 kmph (i) under laboratory condition (ii) on road while four friends
ride the EV together. [2]
(b) Write detailed note on methods of hydrogen production. How to deal with slow reaction rate? [3]
8. (a) The voltage (v volt) and current (I amp) variation with time (in sec) in a resistor is given by 2t 2 + t
+ 5, and 0.2t2 + 0.1t + 0.5 respectively. Calculate average power flow over a time duration of 5
minute after 20 minutes from the start of the system. [2]
(b) Differentiate the voltage-current relationship in a resistor and an inductor of an EV. [1]
(c) Derive an expression for current varying with time in an inductor of an EV. [1]
(d) Explain why the change in the current through an inductor cannot be instantaneously step up or
down to a new value? [1]
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1
9. (a) If the frequency of a step-down DC controller is 20 kHz, calculate the duration for which the
controller switch remains open and close for a 20% duty cycle. [2]
(b) (i) What is battery swapping? (ii) What are the advantages of battery swapping? (iii) Write name
of four commercial service provides of battery swapping in India. [1+1+1]
Section C (Answer any TWO from the following)
10. (a) (i) Explain the working of a capacitor with schematic diagram. (ii) Calculate the charge stored in
a parallel plate capacitor of area 10 m2 separated by 10 cm. (iii) Derive an expression for energy
stored in the electric field between the plates of a capacitor. [1+1+1]
(b) (i) Consider two vehicles 2019 model Chevrolet Cruze which operate using diesel and 2020
model Tesla 3 electric vehicle. If we use the best performing Diesel generator Yanmar for driving our
EV, how it will perform in terms of distance travelled compared to the diesel vehicle? (ii) Why a
diesel-electric setup so much more efficient than a finely tuned diesel automobile? [1+1]
(c) (i) What is thermal runaway? (ii) What causes the battery of an EV overheated? [1+1]
(d) (i) Write at least four desired characteristics of battery thermal management system (BTMS). (ii)
List out the attributes of heat generated due to overpotentials. [1+1]
(e) Draw the schematic of classification/types of battery thermal management system (BTMS) [1]
11. (i) What are the consequences (list out minimum four) of failure of thermal management system of
an EV motor? [1]
(ii) List out different heat losses in the motor of an EV. [1]
(iii) Describe the reason of different heat losses in the motor and its consequences. [3]
(iv)Write name of five fuel cells, their operating temperature range and applications of each type. [2]
(v) Explain the operating principle of Fuel Cell with suitable schematic diagram. [1]
(vi) Write the overall reaction and the reaction that happen at each electrode of a fuel cell. [2]
12. (i) State five battery characteristics. [1]
(ii) What is self-discharge? [1]
(iii) Which is desirable and why: a higher or a lower self-discharge rate for an EV battery pack? [1]
(iv) Under what condition battery self-discharge rate increases? [1]
(v) What is lithium triangle? [1]
(vi) Explain the working of a battery with a schematic diagram. [1]
(vii) Compared to other rechargeable battery technologies, what are the advantages of Li-ion battery?
[2]
(viii) Explain the process of charging and discharging of Li-ion battery with suitable schematic
diagram along with the reaction that occur at the anode and the cathode. [2]
*********************

2
 ME4336 Number of printed pages: 02

ELECTRIC VEHICLE TECHNOLOGY

Mid Semester Examination (Spring) 2022-23
National Institute of Technology Rourkela
Time: 2 Hrs Full Mark: 30
(Numerals in bracket indicate marks; Assume suitably if required and state them clearly)
Answer to all parts of a question should be written together. Section A should be answered
together, preferably in the order of the questions
Section A
(Answer to the point and in short; write answer to all bits at one place)
1. Differentiate between Hybrid electric vehicle (HEV) and plug-in hybrid vehicle (PHEV) with the
help of their working principle and schematic of their system architecture. [2]
2. What is IP67? Explain. [2]
3. What is hotel load? [2]
4. State the factors on which choice of electric propulsion systems for an EV mainly depends. [2]
5. Explain working of Reluctance Motor with suitable schematic diagram. [2]

Section B
6. What is UDDS? The screenshot for UDDS data file for a particular journey carried out for one
minute (at an interval of 5 sec each) in an EV is given in Fig. 1 along with the corresponding
elevation based on GPS measurements (Fig.2). Tabulate and plot the variation of (i) acceleration with
time (ii) slope of the road at each time instant (iii) power requirement at each instant of time with and
without considering slope of the road. Given: density of air 1.23 kg/m3, Cd = 0.24, EV frontal area
2.17 m2, EV weight 1450 kg, driver weight 50 kg, tyre condition good and the EV is accelerating at
1.25 m/s2. Assume suitably if required and state them clearly with proper justification. [5]

Fig. 1 Fig. 2 Fig. 3

7. (a) Calculate the efficiency of the EV for which the cumulative energy consumption is given in Fig.
2. If the battery capacity of the EV is 80 kWh, calculate the range of the EV for full charge. [2]
(b) state and explain (i) Lorentz Force Law, (ii) Biot-Savart’s Law, and (iii) Faraday’s Law [3]
P.T.O

1
 Section C: Answer any ONE from the following
8. (a) A brushless AC motor with 6 pole pairs is operating at an AC frequency of 50 Hz. What is the
synchronous speed of the motor in RPM? [1]
(b) Why do magnets stick to magnetic material? [0.5]
(c) Define slip of rotor. If the slip of the rotor of a brushless AC motor with 4 pole pairs which is
operating at an AC frequency of 60 HZ is 3%. Calculate the rotational speed of the rotor in rpm? [2]
(d) Define motor efficiency. Does any kind of loss occur in an electric motor? If so, then explain
them. [2.5]
(e) For a 75 kW AC induction motor, kc = 0.35, ki = 0.012, kw = 55×10-6, C = 5.6×102. Calculate the
motor efficiency for a motor speed of 1800 rpm which generates a torque of 125 Nm. Plot the
variation of torque with motor speed for motor efficiency of 75 %. [2]
(f) For the Tesla model S, the weight of the EV is 1673 kg. Four friends take a ride of the EV whose
weight are 71 kg, 56 kg, 42 kg, and 52 kg. If the weight to power ratio under laboratory condition
(without any passenger in the EV) is reported to be 4.2 kg/kW. Calculate the time taken in sec to
accelerate the EV from 0 to 60 kmph (i) under laboratory condition (ii) on road while four friends
ride the EV together. [2]
(You have to answer to all the parts of Q 8 together in your answer sheet)
9. Mr Ram decides to drive his EV next week from his residence at his hometown to a nearby hill
station which is at a distance of 16 KM. The hill station lies at an altitude of 4630 m above mean sea
level while the city where Mr Ram resides is at an altitude of 1130 m. The EV tyre condition is
observed to be average. (i) If the EV weight is 1435 kg and Mr Ram weights 65 kg, derive the power
equation assuming the road from Mr Ram’s residence to the hill station is straight and the slope of
the road gradually increases in the forward direction. Given: The EV manufacturer has reported the
EV frontal area 2.34 m2, EV manufacturing date as Feb 2021 and the drag coefficient value on the
date of manufacturing is 0.2, which increases by 5 % for usage of the vehicle by a year compared to
previous year. The air density is function of the altitude which is given by ρ = 1.25 –
2.5×(altitude)×10-2 where the altitude is in kilometre and density is in kg/m3. Hint: Take average air
density value by considering average of maximum and minimum value along the drive. (ii) Calculate
total power requirement (kW), power requirement for rolling resistance, air resistance, hill climbing
along the trip to the hill station with increasing EV speed (km/hr) for the vehicle to be in rolling
motion with an acceleration of 0.75 m/s2. Plot the same on graph paper neatly (with proper scaling)
and find the EV speed at which power required to overcome air resistance exceeds rolling resistance
and hill climbing component. (iii) Tabulate the value of power requirements for rolling resistance, air
resistance, hill climbing, and accelerating the EV and their value in percentage of total power
requirement when the EV is running at a speed of 50/3 m/s. Assume suitably if required to solve this
problem and state them clearly with proper justification. [5+3+2]

2
 ME4336 Number of printed pages: 02

ELECTRIC VEHICLE TECHNOLOGY

End Semester Examination (Spring) 2022-23
National Institute of Technology Rourkela
Time: 3 Hrs Full Mark: 50
(Numerals in bracket indicate marks; Assume suitably if required and state them clearly)
Answer to all parts of a question should be written together and in the order of the questions.
Section A should be answered together and in the order of the questions
Section A
(Answer ALL, to the point and in short; write answer to all bits at one place)
1. How complete electrification of transport system/ mobility system can be achieved? [2]
2. Write battery characteristics (minimum eight) [2]
3. What is Lithium triangle? [2]
4. Why batteries do not return 100% of the energy put in to it? [2]
5. State advantages and disadvantages of steam reforming of ethanol. [2]

Section B: Answer any FOUR from the following

6. (a) Why a diesel-electric setup is so much more efficient than a finely tuned diesel automobile? [2]
(b) What are the origin of heat generation in a battery. [1.5]
(c) Why current cannot be instantaneously changed in an inductor? [1.5]
7. Describe EV charging modes and different charging connectors used with the help of suitable
diagrams. [5]
8. (a) A resistor coil used to convert electrical energy into thermal energy, has a resistance value of 48
Ohm. If the voltage applied across the two ends of the resistor coil varies as v(t) = 2t 2 - 20t + 50
where v in volt, and t in minute. Calculate (i) total energy converted by the resistor, and (ii) average
power flow over in a time duration of 15 minute. [3.5]
(b) Describe different charging levels of an EV [1.5]

9. (a) For the Tesla model S, the weight of the EV is 1673 kg. Four friends take a ride of the EV whose
weight are 71 kg, 56 kg, 42 kg, and 52 kg. If the weight to power ratio under laboratory condition
(without any passenger in the EV) is reported to be 4.2 kg/kW. Calculate the time taken in sec to
accelerate the EV from 0 to 60 kmph (i) under laboratory condition (ii) on road while four friends
ride the EV together. [2]
(b) Name different battery cooling techniques/methods. State advantages and disadvantages of each
method of cooling. [3]
10. (a) Write note on Li-ion battery [3.5]
(b) State (i) Lorentz Force Law, (ii) Biot-Savart’s Law, and (iii) Faraday’s Law [1.5]
P.T.O
1
 Section C: Answer any TWO from the following
11. (a) A brushless AC motor with 6 pole pairs is operating at an AC frequency of 50 Hz. What is the
synchronous speed of the motor in RPM? [1]
(b) Define slip of rotor. If the slip of the rotor of a brushless AC motor with 4 pole pairs which is
operating at an AC frequency of 60 HZ is 3%. Calculate the rotational speed of the rotor in rpm? [2]
(c) Define motor efficiency. Does any kind of loss occur in an electric motor? If so, then explain
them. [2]
(d) What is duty cycle? If total cycle time for a DC controller is 40 × 10-5 sec, and the time duration
for which the switch is open is 15 × 10-5 sec, calculate the value of duty cycle and voltage frequency.
[2]
(e) Explain the working of an integrated reactor system for steam reforming of ethanol with the help
of suitable flow chart diagram/schematic diagram. [2]
(f) What is Fischer-Tropsch process? [1]
12. (a) Define Henry. Derive (i) an expression for current which varies with time, and (ii) an expression
for energy stored in the electric field of an inductor element. The voltage variation with time over a
period of 15 secs in an inductor coil having its inductance value of 10 Henry is given by v = 2t 2 - 20t
+ 50 where v in volt, and t in second. with initial current of 10 amperes. Calculate energy stored in
the inductor’s magnetic field after 15 seconds. [4]
(b) Explain the working of a H bridge AC controller with suitable schematic diagram. Plot the
variation of motor voltage (V) with time i.e. the pulse width modulation for AC control. [2]
(c) What is thermal runaway? What are the consequences that can happen in the event of a thermal
runaway? [2]
(d) What are the causes of thermal runaway? [1]
(e) What are the desired characteristics of battery thermal management system. [1]
13. (a) Derive an expression for energy stored in the electric field between the plates of a capacitor.
Calculate energy stored in the capacitor if the capacitor has two square shape plates each of area 4m 2
and are separated by a distance of 10 cm, and a potential difference of 100 V is applied across the
two plates. Also calculate charge stored in the capacitor. [3]
(b) Explain the working of step-down DC controller with suitable schematic diagram. What is pulse
width modulation? What happens when the transistor switch is on and off. [3.5]
(c) Write detailed note on methods of hydrogen production. How to deal with slow reaction rate?
[3.5]
**************