# Electric Vehicles | Week 4

Course Name: Electric Vehicles – Part 1

#### These are Electric Vehicles Week 4 Assignment 4 Answers NPTEL

For Question 1 to 4 –

Consider an EV with the following details. Tire rolling friction coefficient = 0.01, Ratio of Gear ratio to the radius of the tyres = 15, acceleration due to gravity = 9.8 m/s2 . Equivalent mass for rotational mass can be taken as 5% of total mass. The wheel is connected to a three phase induction motor with a gear. The maximum torque of the motor is 200 Nm. The maximum percentage grade of the vehicle is 25.
EV starts from rest and operates in constant torque region. Aerodynamic force is neglected. Rated speed of the motor is 5639 rpm.

#### Q1. Tractive effort isa. 2000 Nb. 1000 Nc. 3000 Nd. 1500 N

Q2. Mass of EV is
a. 1236 kg
b. 1262 kg
c. 1200 kg
d. 1365 N

These are Electric Vehicles Week 4 Assignment 4 Answers NPTEL

Q3. Acceleration is
a. 2.2 m/s2
b. 1.8 m/s2
c. 1.2 m/s2
d. 2.6 m/s2

Q4. Power rating of the motor
a. 117.5 kW
b. 116.8 kW
c. 118.1 kW
d. 120 kW

These are Electric Vehicles Week 4 Assignment 4 Answers NPTEL

For Questions 5 to10 –

Consider an EV with the following details. Total mass = 1200 kg, front area = 2 m2, aerodynamic drag coefficient = 0.25 and tire rolling friction coefficient = 0.02, air density = 1.25 kg/m3 , acceleration due to gravity = 10 m/s2 . Equivalent mass for rotational mass can be taken as 6% of total mass. The wheel is connected to a three phase induction motor with a gear. Gear efficiency is 0.9. Induction motor is operating in constant torque region. The vehicle starts from rest and linearly reaches velocity of 80 km/hr in 10 seconds.

Q5. Tractive effort at 10 sec is
3218.1 N
3058.3 N
10570.3 N
3232.54 N

Q6. Power at the wheels is
7144 W
64.4 kW
6429.6 W
71.5 kW

These are Electric Vehicles Week 4 Assignment 4 Answers NPTEL

Q7. Power at the motor shaft is
71.56 kW
71.56 kW
79.5 kW
7937.78 W

Q8. Percentage grade of the vehicle is
26.2
27.8
26.36
24.77

These are Electric Vehicles Week 4 Assignment 4 Answers NPTEL

Q9. Speed of the motor at 3 seconds is
24 m/sec
2400 m/sec
666.6 m/sec
6.7 m/sec

These are Electric Vehicles Week 4 Assignment 4 Answers NPTEL

Q10. Tractive effort at 5 seconds is
2942.5 N
3218.13 N
3102.3 N
3058.3 N