All Courses
All Courses
Courses by Software
Courses by Semester
Courses by Domain
Tool-focused Courses
Machine learning
POPULAR COURSES
Success Stories
Q1. Which types of power converter circuits are employed in electric and hybrid electric vehicles? A converter is an electrical circuit that accepts a DC input and generates a DC output of a different voltage, usually achieved by high frequency switching action employing inductive and capacitive filter elements. Power conversion…
Deepak Gaur
updated on 22 Mar 2021
Q1. Which types of power converter circuits are employed in electric and hybrid electric vehicles?
A converter is an electrical circuit that accepts a DC input and generates a DC output of a different voltage, usually achieved by high frequency switching action employing inductive and capacitive filter elements. Power conversion is converting electric energy from one form to another such as converting between AC and DC; or changing the voltage or frequency, or some combination of these.
A power converter is an electrical circuit that changes the electric energy from one form into the desired form optimized for the specific load. A converter may do one or more functions and give an output that differs from the input. It is used to increase or decrease the magnitude of the input voltage, invert polarity, or produce several output voltages of either the same polarity with the input, different polarity, or mixed polarities such as in the computer power supply unit.
The DC to DC converters is used in a wide range of applications including computer power supplies, board-level power conversion and regulation, dc motor control circuits, and much more.
The converter acts as the link or the transforming stage between the power source and the power supply output. There are several kings of converters based on the source input voltage and the output voltage and these fall into four categories namely the AC to DC converter known as the rectifier, the AC to AC cyclo-converter or frequency changer, the DC to DC voltage or current converter, and the DC to AC inverter
In electrical engineering, power engineering, and the electric power industry, power conversion is converting electric energy from one form to another such as converting between AC and DC; or changing the voltage or frequency; or some combination of these.
There are mainly three types of Power Converter circuit used in electric and hybrid electric vehicles are:-
1. Rectifier (AC to DC Converter)
A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The process is known as rectification since it "straightens" the direction of the current.
An on-board charger is used to charge the battery from an external AC Power Supply.
Simple Half Wave Rectifier Circuit
2. Inverter (DC to AC Converter)
An inverter is a power electronic device or circuitry that changes direct current (DC) to alternating current (AC). The input voltage, output voltage and frequency, and overall power handling depend on the design of the specific device or circuitry.
The traction inverter converts energy from the batteries to the traction motor, which propels the vehicle.
A simple inverter circuit
3. Chopper (DC to DC Converter)
A chopper circuit is used to refer to numerous types of electronic switching devices and circuits used in power control and signal applications. A chopper is a device that converts fixed DC input to a variable DC output voltage directly. Essentially, a chopper is an electronic switch that is used to interrupt one signal under the control of another circuit is used to refer to numerous types of electronic switching devices and circuits used in power control and signal applications. A chopper is a device that converts fixed DC input to a variable DC output voltage directly. Essentially, a chopper is an electronic switch that is used to interrupt one signal under the control of another.
A DC-to-DC converter steps down the power to lower voltages. This is used to control the doors, heater and windows.
Q2. 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'.
Separately Excited DC Motor
separately excited dc motor are like other DC motors, these motors also have both stator and rotor. Stator refers to the static part of the motor, which consists of the field windings. And the rotor is the moving armature that contains armature windings or coils. Separately excited dc motor has field coils similar to that of shunt wound dc motor. The name suggests the construction of this type of motor. Usually, in other DC motors, the field coil and the armature coil both are energized from a single source. The field of them does not need any separate excitation. But, in a separately excited DC motor, a separate supply Provided for excitation of both field coil and armature coil.
Here, the field coil is energized from a separate DC voltage source and the armature coil is also energized from another source. The armature voltage source may be variable but, independent constant DC voltage is used for energizing the field coil. So, those coils are electrically isolated from each other, and this connection is the specialty of this type of DC motor.
Given Inputs
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
Tv=24.7+(0.0051)w2 , consider this as equation-1 where
Tv =Torque in Nm
w =Angular velocity in rad/sec
Also, we know that Torque Speed Characteristics of a Motor can be given by the formula
T=KmΦEsRa-(KmΦ)2Raw , considering this as Equation-2 where
T =Torque in Nm
Km = Motor Constant in Nm√W
Φ =Magnetic Field Strength in Wb/m^2
Es =Supply Volatge
Ra =Armature Resistance ohms
w = Angular Velocity in rad/sec
Given Duty-Cycle is 70%
Vs=0.7Voltage=0.7â‹…72
Vs=50.4V
Substituting the given input values in Equation-2
T=0.7â‹…50.40.5-0.720.5w=70.56-0.98w
Equating equation-1 and equation-2 to find a solution
70.56-0.98w=24.7+0.0051w2
Transforming the equation we get a quadratic equation
0.0051w2+0.98w-45.86=0
Solving the Quadratic Equation we get the values of w that satisfying the above equation.
w1=-b+√b2-4ac2a=-0.98+√0.982-4⋅0.0051⋅(-45.86)2⋅0.0051=38.9150
w2=-b-√b2-4ac2a=-0.98-√0.982-4⋅0.0051⋅(-45.86)2⋅0.0051=-231.0718
Matlab Script for solving the Quadratic Equation and solving the equation by finding the intersection of the two curves
Let Equation-1, Tv=24.7+(0.0051)w2 represent a Quadratic function and Equation-2, T=KmΦEsRa-(KmΦ)2Raw represent a linear function.
The point of intersection of the two functions gives us the required solution for the Steady State, satisfying both functions.
Matlab Script
%Program to find Vehicle Steady State
%Let the rpm ranges from 0 to 15k
rpm=linspace(0,3000,20000);
%Converting rpm to angular velocity
w=2*pi.*rpm/60;
%The Given Formula for Vehicle Torque is
T_given=24.7+0.0051.*(w.^2);
%given data
v=72; %rated volatge in volt
a=400; %rated armature current in ampere
ra=0.5; %Ohm
km_phi=0.7; %Volt second
%supply volatge when duty cycle=0.7
vs=0.7*v;
%the torque can be given by the formula
t=(km_phi*vs/ra)-(km_phi^2/ra).*w;
%plotting the two curve
plot(w,T_given)
hold on
plot(w,t)
title('Torque vs Angular Velocity');
xlabel('Angular Velocity');
ylabel('Torque');
%finding the intersection point for two curves
dfr=abs(T_given-t);
index=find(dfr<0.01);
w_sol=w(index);
str={'Steady State at w= ',num2str(w_sol)};
plot(w(index),t(index),'r*');
text(w(index),t(index),str);
legend('Quadratic Torque Function','Linear Torque Function','Steady State Solution');
grid on
%finding the roots for the quadratic equation
a=0.0051;
b=0.98;
c=-45.86;
d=sqrt(b^2-4*a*c);
w1=(-b+d)/(2*a);
w2=(-b-d)/(2*a);
Result
The solution obtained for the steady-state is at w=38.91rad/sec, both the methods gave the same output as explained above.
Q3. Explain in brief the author’s perspective on Induction Versus DC Brushless Motors.
The author makes a detailed comparison between Induction and DC Brushless motor in order to decide which one is better. The author compares each aspect of the two machines from construction, operation, efficiency, and control. The
Differences Between DC and Induction Motor
In the end, the author concludes 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.
References
1. https://semiengineering.com/electric-cars-gain-traction-but-challenges-remain/
2. https://en.wikipedia.org/wiki/Power_inverter
3. https://www.sunpower-uk.com/glossary/what-is-a-power-converter/
Leave a comment
Thanks for choosing to leave a comment. Please keep in mind that all the comments are moderated as per our comment policy, and your email will not be published for privacy reasons. Please leave a personal & meaningful conversation.
Other comments...
2D Heat Conduction Simulation
Steady-State Heat Conduction Steady-state conduction is the form of conduction that happens when the temperature difference(s) driving the conduction are constant, so that (after an equilibration time), the spatial distribution of temperatures (temperature field) in the conducting object does not change any further. Thus,…
18 Sep 2023 06:04 PM IST
Design of an Electric Vehicle
Electric Vehicle Electric vehicles are also called Battery Electric Vehicles (BEV). These are fully-electric vehicles with rechargeable batteries and no gasoline engine. Battery electric vehicles store electricity onboard with high-capacity battery packs. Their battery power is used to run the electric motor and all onboard…
18 Sep 2023 05:31 PM IST
Construction of a Simple Multi Cell Battery Pack
Q1a. How weakest cell limits the usable capacity of the battery pack? The weakest cell limits the because it sets a barrier for the entire battery pack to work with limitations. The weak cell may not fail immediately but will get exhausted more quickly than the strong ones when on a load. On charge, the low cell fills…
10 Sep 2023 06:07 PM IST
Battery Thermal Management
Thermal Management All batteries depend for their action on an electrochemical process whether charging or discharging and we know that these chemical reactions are in some way dependent on temperature. Nominal battery performance is usually specified for working temperatures somewhere in the + 20°C to +30°C range…
05 Dec 2021 05:23 PM IST
Related Courses
0 Hours of Content
Skill-Lync offers industry relevant advanced engineering courses for engineering students by partnering with industry experts.
© 2025 Skill-Lync Inc. All Rights Reserved.