Week-6 Challenge: EV Drivetrain
1.Which types of power converter circuits are employed in electric and hybrid electric vehicle?
Power electronic converter controls the power flow from source to motor,power converter drive used in DC motor is DC drive & drive used in AC motor is AC drive.
Power conversion is converting electrical energy from one form to another such as AC & DC or changing voltage or frequency.
Converters used in vehicle as follows.
DC-DC converters;
used in EV & HEV to covert the unregulated DC input to regulated DC output,also known as DC Choppers,can be used to interface the elements in the electric power train by boosting or chopping energy levels,different configurations of EV power supply show that atleast one DC/DC converter is necessary to interface the battery.
Amount of powerflow between input & output can be controlled by adjusting duty cycle ratio.
following devices can convert DC to DC,1.Linear regulator,2.voltage regulator,3.Motor generator,4.SMPS
DC-AC convertors:
Converts DC power from the battery to AC power to the supply of motor which is known as inverters.it controls both magnitude & frequency output AC voltages as per requirement the DC power is converted intor AC which is either single phase or three phase AAC supply.
Hybrid & other EV's two key elements work together to manage power & rechagre the circuits,inverters & converters
following devices used covert the DC to AC ,1.Power inverter,2.motor generator,3.SMPS
AC-DC Converters;
Converts power from the AC to DC & feeds the battery ,also known as onboard charger which is commonly known as rectifier.Normally transformer used to adjust AC source to get step-up & step down supply which is rectified by inverter,in EV,s & PHEV's equipped not only with DC/DC coverters also AC/DC converters which supplies electric power to car's battery from commericial transformer.
following devices used AC-DC converters;1.Rectifier, 2.mains power supply unit,3.SMPS
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 :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,duty cycle=70%=0.7,actual voltage =0.7*72=50.4V
ω=(v/kϕ)-(Ra/(kϕ)^2)T
ω=(50.4/0.7)-(T*0.5/(0.7)^2)
ω=72-(0.5T/0.49)
T=70.56-0.98ω at steady state Tv=T
so 24.7+(0.0051)ω^2=70.56-0.98ω
forms quadratic equations ω^2+192.156ω-8992.156=0
ω=38.915rad/s & ω=-231.0718rad/s
Steady state speed of EV at duty cycle of 70% is 38.915rad/s
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
Results
4.Induction VS DC brushless motors by Wally Rippel,Telsa
In this blog author's perpesctive is
1.They compared old & today's technology like battery drive machine like motors ,wants to get to know it will get stable technology,want to know that which motor is better for electric vehicle BLDC or an induction motor,Early days lead acid battery ,DC brush motor & contact controllers are replaced by Lithium-ion batteries DC brushless motors,modulating inverters.
2.So they compared these two technology,how they work what are the differentiates them?Brushless DC motor VS induction motor
3.Difference between the two motors is in the rotor,since induction motor has no magnet in rotor whereas brushless DC motor has permanent magnets on the rotor,explain about poer supply to motors & compared the which one is better for EV cars.
4.As per author review ,brushless DC motor will useful for Hybrid EV & induction motors will be useful for pure EV,there are more common hardware are used in both motors,as per application Brushless DC motors has higher torque & induction motors has constant speed