Week-6 Challenge: EV Drivetrain
FOR QUESTION1:
1.Which types of power converter circuits are employed in electric and hybrid electric vehicle?
We have 3 types of power converters are mostly use in electric &hybrid EV
1)AC to DC converters (rectifier)-these converters are use in plugin EV&HEV for charging DC battery from AC source
2)DC-DC converters (chopers) are used to where vehicle has DC motors,DC supply from battery is converted into variable DC to control the speed of motor.they are called DC drives.
3)DC-AC converters (inverter) are used to converted to use the if EV(or)HEV has AC induction motor,DC supply from battery is converted into variable AC ti run the motor in variable speed, this device is known as VFD.
FOR QUESTION
2) An Electric Vehicle's powertrain with 72V battery pack in shown in the diagram below. The duty ratio for acceleration operation is 'd1' and for the braking operation the duty ratio is 'd2'.
The other parameters of the electric vehicle is given below,
Motor and Controller Parameters:
Rated Armature voltage= 72 V
Rated armature current= 400 A
Ra= 0.5Ω, KΦ= 0.7 Volt second
Chopper Switching frequency= 400 Hz
The vehicle speed-torque characteristics are given by the below equation
What is EV steady state speed if duty cycle is 70%?
answer:
given,rated armature voltage=72v
rated armature current= 400 A
Ra= 0.5Ω,
KΦ= 0.7 Volt second
Chopper Switching frequency= 400 Hz
duty cycle=70%
vehicle output coltage(Vv)=battery voltage*duty cycle
=72*70/100=50.4
w=steadt state speed of vehicle(rps)
vehicle torque(Tv)=(Vv-KΦ)*KΦ/Ra
=(50.4-w*0.7)/0.5
=70.56-0.9w
Tv=24.7+(0.0015)w^2, equating both equations,
70.56-0.98w=24.7=(0.0051)w^2
(0.oo51)w^2+0..98w-45.86=0
by solving tyhe two equations we get the values of
w1=38.91
w2=-231.071
as w2 is negative.so, we will consider the value of w1, so the steadt soeed of vehicle is 38.91 rps.
FOT QUESTION:3
3. Develop a mathematical model of a DC Motor for the below equation using Simulink.
ω">ωω= V/Kϕ">ϕϕ -Ra/Kϕ">ϕϕ^2 .T
Solution:
here the blocks are used in this model are conctant block,ramp block,product,divide,scope,square block.
Similink model:
values of vehicle voltage motor constant (k......,armature resistance (Ra) are taken from the question 2 data
after making the math model for equation,....=V/K....,-Ra...^2.
we have given run time in 100 seconds ,then run the simulink,we will get the results as shown in below.
this is the speed torque characteristics of dc motor,it shows starting torque is about 71N-m,torque becomes zero when speed is 70.5
Referance link:
https://drive.google.com/file/d/1tK2XcuFA0xu91vJ1f9W9rZl5q9yXSdY-/view
FOR QUESTION4:
Refer to the blog on below topic:
Induction Versus DC brushless motors by Wally Rippel, Tesla
Explain in brief about author’s perspective.
BLDC motor:
A Brushless DC Electric Motor (BLDC) is an electric motor powered by a direct current voltage supply and commutated electronically instead of by brushes like in conventional DC motors. While they have been successfully applied in the automotive, HVAC, electronic, computer, semiconductor and medical industries, BLDC motors have long been used in industrial applications such as actuators, feed drives for CNC machines, industrial robots, extruder drives, among others.
AC induction motor:
An induction motor or asynchronous motor is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding. An induction motor can therefore be made without electrical connections to the rotor. General uses for AC motors include pumps, water heaters, lawn and garden equipment, ovens, and off-road motorized equipment.
Differances between BLDC motor and AC induction motor:
CONCLUSION:
in 1st question: we explain the types of cinverters are mostly used in electric and HEC
in 2nd question:we will calculate the value of w1 that is w1=38.91 at steadt state.
in 3rd question: we will costruct the simulink and to get the output of math model DC motor.
in 4th question: we will explain about the BLDC motorand AC induction motor.