Week-6 Challenge: EV Drivetrain

1-

Types of power converter circuits in electric vehicles:

• AC-DC converters (Rectifiers): Used in Onboard chargers of the vehicle.
• DC-DC converters (Choppers): Used in the auxiliary power supply for other vehicle accessories, Inverter supply (For AC induction motor powertrain), Supply and control of the DC motor (For DC motor powertrain)
• DC-AC converter (Inverters): Used in supplying and controlling the AC induction motor used in the EV powertrain.
• AC-AC converter: Used in fan regulator (stepless fan regulator), and EV wireless charger

2-

Steady-state case: The motor and vehicle characteristics don’t change by time, then there is an equilibrium between the electric torque of the motor and the vehicle load.

Tv=Tm

From the given equation

Tv = 24.7+0.0051wm^2

And the wm equation is

Wm = ((v/Kphi) – (Ra/Kphi^2))*T

Then Tm = ((Kphi*v)/Ra) – (Kphi^2*wm/Ra)

Duty ratio: When duty ratio is 70% then the RMS voltage of the input of the motor is 70% of the rated motor voltage

Tv = 24.7+0.0051w^2

And by substitution by the given values then

Tm = 70.56-0.98wm

As previously mentioned Tm = Tv

Then

24.7+0.0051w^2 = 70.56-0.98wm

0.0051 wm^2 + 0.98 wm – 45.86 = 0

By solving this equation wm = 38.9 rad/s

And the torque equals 32.4 Nm

3-

The given equation is represented as a mathematical model

The model is given in the attached file

4-

	DC Brushless motor	AC Induction motor
Used in	Hybrid electric vehicles	Pure electric vehicles
Stator	Basically, the same	Basically, the same
Control	Absolute position sensor Easy to control	Speed sensor Very complex control laws lead to higher development costs
Heat	Much less rotor heat, easier rotor cooling, and peak point efficiency is generally higher	Opposite, Peak point efficiency is a few percentages less compared to DC Brushless drive
Power factor	Can operate in unity factor	0.85 is the best power factor
Magnetic field	Easy to control	Very complex control laws
Permanent magnets	Expensive magnets	No magnets