Week-6 Challenge: EV Drivetrain

HYBRID VEHICLE

Since hybrid vehicle doesn’t have an option to charge the vehicle from eternal power supply, the following types of power converters may be used

1. DC to DC converter to store the generated energy into the battery, and to provide auxiliary supply to circuits of different voltage levels.
2. DC to AC converter if motor used is an AC motor.

PLUG IN HYBRID

supports external charging option so

1. AC to DC converter if external supply is AC. Not required if it is a DC fast charging option.
2. DC to AC converter if motor used is an AC motor.
3. Given Battery voltage=72, Duty cycle= 70%

2)The output voltage of converter as per given duty cycle is = 0.7* 72 = 50.4V

Given torque = 24.7+o.0051w²

Angular velocity w= v/kØ-(Ra/(kØ)² )T

Can be written as T= vkØ/Ra – w(kØ)²/Ra

Given kØ= 0.7 Ra=0.5 ohm

T=70.56-0.98w

Equating the given torqe eqation and actual torqe equation

24.7+0.0051w² = 70.56-0.98w

0.0051w²+0.98w-45.86=0

Solving eq we get w= 38.91 rad/sec

= 38.91/2*3.14 rev/sec = 6.19rev/sec =371rpm

3)Model uploaded as per given torque equation

4)The author here compared DC brushless motors and AC induction over a wide range of aspects. First he mentioned there are different types of engines and options available in market just to meet customer specific requirements, rather than declaring one as the best. He later discussed about technological upgrades in electric vehicles to lithium ion batteries, brushless and induction motors. He primarily focussed on these motors in this article.

a) From construction point of view both stators are same whereas rotors brushless motors uses a permanent magnet, induction motor uses steel bars.

b) AC induction motor is less costly and easy to construct than DC brushless motor.

c) Induction machines inverter costs less but has difficult control logic than DC motors.

d) Brushless motors are useless without a inverter and AC induction motor needs inverter to power it from a battery source and to vary its speed and torque.

e) DC motors have better torque characteristics than AC induction motor.

f) Peak point power efficiency of brushless motors is high while for AC induction motors average efficiency is high since they can control magnetic field strength.

The author concluded that DC motors rule hybrid and AC motors rule pure EV’s. If hybrids became more electric intensive we may find both motors in a same vehicle in future.