Week-6 Challenge: EV Drivetrain
AIM:
1.To identify the types of power converter circuits employed in electric and hybrid electric vehicle.
2. To calculate the steady state speed of an EV with given inputs if duty cycle is 70%.
3. Refer to the blog and explain in brief about author's perspective.
STUDY#1:-
Q.1: Which types of power converter circuits are employed in electric and hybrid electric vehicle.
POWER ELECTRONIC CONVERTERS:-
In electric and hybrid electric vehicle (EV/HEV), Power Electronics defined as Power Electronics defined as the application of solid the application of solid.
state (devices) electronics for the control and state (devices) electronics for the control and
conversion of electric power. conversion of electric power.
Power Electronics Application Power Electronics Application
Power electronics have already found an important place in
modern technology and are now used in a great variety of highpower product, including heat controls, light controls, electric motor control, power supplies, vehicle propulsion system and high voltage direct current (HVDC) system.
AC - DC CONVERTER: (ON BOARD CHARGER):-
AC to DC converters are most commonly used in plug- in hybrid Electric vehicles(PEV). these vehicle get their propulsion power from an external electrical electricity source (charging stations) which is alternating current. the battery needs to be charged using a direct current source. For this purpose, AC to DC converter is employed in a PHEV and PEV.
DC - DC CONVERTER.
A DC-to-DC converter is an electronic circuit or electromechanical device that converts a source of direct current (DC) from one voltage level to another. It is a type of electric power converter. Power levels range from very low (small batteries) to very high (high-voltage power transmission).
Most DC-to-DC converter circuits also regulate the output voltage. Some exceptions include high-efficiency LED Power sources, which are a kind of DC to DC converter that regulates the current through the LEDs, and simple charge pumps which double or triple the output voltage.
DC - AC CONVERTER (INVERTER):-
The DC/AC converter is required to convert the dc power to a suitable ac power for the electric machine. the power output from battery pack (DC current ) is converted using inverter to be used in electric motor AC current).
STUDY#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%.
Given:-
The following input parameters are given:-
Battery pack voltage (V) = 72v
Rated armature current = 400A
Armature resistance (Ra)=0.5ohm
Motor constant(K)=0.7
Chopper switching frequency = 400 Hz
Duty cycle= 70%w
solution: solution is uploaded below.
Q.3. Develop a mathematical model of a DC Motor for the below equation using Simulink.
ω">ωω= V/Kϕ">ϕ -Ra/Kϕ">ϕ^2.T
SOLUTION : The model is uploaded below.
ω">ω= V/Kϕ">ϕ -Ra/Kϕ">ϕ^2 .T
voltage(v) =220v
resistance (Ra)=0.017ohm
torque=150NM
Kϕ=0.05
OUTPUT =ω">ω=3380
the model is uploaded below.
Q.4:
Refer to the blog on below topic:
Induction Versus DC brushless motors by Wally Rippel, Tesla
Explain in brief about author’s perspective.
The following points can be concluded from the above topic:
In the beginning, author descibes the dominance of internal combustion engines (ICE) in the world of automobile industry and also discuss differnt types of engines. He explains that all engines were similar and it was up to user to select according motor and brushless. DC motors and presents his view that these two technologies will be widely used for the coming years.
Then he explains the working of both 3-phase induction motor and a brushless DC motor.
Now the author has done comparison between these two technologies and stated some advantages and disadvantages of each.
Induction motor have some advantages like: it has no magnet. the motor has the ability to start under load. No inverter is needed. Some disadvantages of induction motors are: They are constant speed machines. when operation from utility power, they have limited starting torque and somewhat limited running peak torque capabilities, when compared to DC type machines.
Brushless DC motor have some advantages like: much less rotor heat is generated with the dc brushless drive. The peak point energy efficiency for a dc brushless drive will typically be a few percentage points higher than for an induction drive. some disadvantages of brushless DC motor are: As machine size grows, the magnetic losses increase proportionately and part load efficiency drops. permanents magnets are expensive and difficult to handle due to very forces that come into play when anything ferromagnetic gets close to them.
Finally the author couldn't choose which drive is better than the other but makes it clear that DC brushless drives will likely continue to dominate in the hybrid and coming plug-in hybrid markets, and that induction drives will likely maintain dominance for the high-performance pure electrics.
CONCLUSION : hence done all the above question and the output are uploaded below.