Challenge

Week-6 Challenge: EV Drivetrain

DC-DC converter is an electronic circuit that converts DC voltage from one voltage level to another. It can be step up or step down of voltage.
This type of converter is also known as chopper.
The electric components inside the vehicle vary in their voltage requirements, with most running on much lower voltage. This includes radio, dashboard readouts, air conditioning, and in-built computers and displays.
It can be unidirectional or bidirectional.
Most of the components are bidirectional, allowing power to go from the battery to the inverter, which rotates the motor.
When decelerating, the vehicle's momentum turns the motor, which is now acting as a generator, drives power back through the inverter and charges the battery.
DC-DC converter converts higher voltage DC power from the traction battery pack to the lower-voltage DC power needed to run vehicle accessories and recharge the auxiliary battery.

DC-AC converter change a dc input voltage to a symmetric ac output voltage of desired magnitude and frequency.
This type of converter is also known as inverter.
The inverter can change the speed at which the motor rotates by adjusting the frequency of the alternating current.
When the vehicle has to be accelerated, the accelerator pedal sends a signal to the controller which adjusts the vehicle's speed by changing the frequency of the AC power from the inverter to the motor.

AC-DC converter takes a harmonic AC input and converts it to a DC output.
These concerters are also known as rectifiers.
Inverters are used in Ev/Hev mainly for the on-board charging purpose. Since the charging stations use AC power to charge the vehicle and the battery stores DC power, rectifiers are used to convert AC-DC.

Given,

Rated Armature voltage,Va= 72 V

Rated armature current, Ia= 400 A

Ra= 0.5Ω

KΦ= 0.7 Volt second

Chopper Switching frequency= 400 Hz

Duty cycle= 70%(0.7)

Speed- Torque characteristics is given by:

............................(1)

To find voltage, V:

V= Va* duty cycle

V=72*0.7

V= 50.4V

To find Torque,Tv:

Tv= (V*KΦ- ((KΦ)^2*w))/Ra

=(50.4*0.7)-((0.7)^2*w))/0.5

Tv= 70.56-0.98w .........................................(2)

Comparing equation (1) & (2), we get,

(0.0051)w^2+0.98w-45.86=0

By solving the quadratic equation, we get,

w= -231.07 ,w=38.91

Neglecting negative value,

the steady state speed, w= 38.91 rad/s ~ 371.75rpm

By substituting the value of w in equation (2), we get

Tv= 32.4N-m

3. Mathematical model of a DC motor for the given equation:

ω">ω= V/Kϕ">ϕ -(Ra/Kϕ">ϕ^2 )*T

The author thinks both BLDC and induction motors will rule over automotives in Ev and Hev segments since PMSM is expensive and come with complex control of rotors.
He also thinks that the hybrid and upcoming plug-in hybrid markets are anticipated to continue to be dominated by BLDCs, while the high-performance pure electrics market is likely to continue to be dominated by Induction motors.
He's keen to know what will occur as hybrids' electrical requirements increase and their performance levels rise.

Ship work like this
in your own course.