Week-6 Challenge: EV Drivetrain
Aim:
To perform the EV Dive Train.
1. Which types of power converter circuits are employed in electric and hybrid electric vehicle?
Ans:- A motor drive consists of an influence device and also the controller. the ability convertor handles the flow of bulk power from the supply to the motor input terminals. The controller method the command input and also the feedback info to get the shift signals for power device semiconductor switches.
- the ability device is a DC drive supply a CD motor or AN AC drive supply AN AC motor.
- A DC/DC device in its basic type converts unregulated DC input voltage at a particular level to regulated DC output voltage at a special level with terribly high conversion potency. These area unit operated at terribly high frequency. The switches area unit turned ON and OFF by pulse breadth modulation(PWM).
- the ability device is created of high power fast-acting semiconductors devices, like a bipolar semiconductor device. There area unit another transistors like MOSFET, IGBT, SCR, GTO, MCT. These devices area unit used as on-off physical science switch to convert the mounted offer voltage into a variable voltage and variable frequency offer.
- of these devices have an effect input gate or base through that the devices area unit turned on and off as per the command generated by the controller.
- There area unit 2 varieties of step converters. once an occasional voltage input is regenerate into a high voltage output it's a increase device. Whereas once a high voltage input is regenerate into an occasional voltage output it's a step down device.
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 are 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 the duty cycle is 70%?
As the torque formula is given, we need to find the speed in rad/sec. Use the other expression available which is given below:
T = torque
V = armature voltage
R = resistance
w = speed rad/sec
Compare the two equations:
24.7 + 0.0051*w^2 = ((v*k)/R) - ((k^2)*w/R)
24.7 + 0.0051*w^2 = (72*0.7*0.7)/0.5 - (0.7^2/0.5)*w = 24.7 + 0.0051*w^2
70.56 - 0.98*w = 24.7 + 0.0051*W^2
w^2 + 192.15*w - 8992.15 = 0
In order to find the roots use following formula
As the speed value can not be negative
w = 38.95 rad/sec.
3) Explain in brief about author’s perspective.
- within the journal of induction and DC brushless motor, the author has mentioned concerning positives and negative aspect of each the induction and DC motor. within the journal, the fundamental construction of each the induction and DC brushless motor is explained.
- just in case of DC brushless motor, permanent magnets area unit used that produces a rotating force field. This force field once induces a current within the conductor. This current leads to force generation within the rotor and this leads to rotation of the rotor.
- Whereas just in case of induction motor, this is equipped to the mechanical device which ends within the generation of voltage, once this voltage comes connected with the rotor that is usually a coop sort, this leads to current iatrogenic within the rotor. in contrast to the DC motor, the rotor consists of conductors plates and placed in a very cage-like structure. This additionally consists of bars around them within which current get iatrogenic and therefore the rotor starts rotating.
- one among the most variations is that abundant less rotor heat is generated with the DC brushless drive. Rotor cooling is simpler and peak purpose potency is usually higher for this drive. it's mentioned that the DC brushless will drive at unit power issue, whereas the most effective power issue for the induction drive is concerning eighty fifth.
- just in case of DC brushless motor, the strength of the force field is adjustable. once at low speed most|the utmost|the most} torsion is needed force field ought to be maximum, i.e. electrical converter and motor current maintained at their lowest optimize potency. Whereas there's no such adjustment just in case of induction motor.
- As machine size grows, magnetic losses will increase proportionately and half load potency drops. just in case of induction motor, as machine size grows, losses don't essentially grow.
- the development of DC brushless motor is expensive compared with associate induction motor, thanks to the employment of permanent magnets.
- but thought the speed variation of induction motor depends upon the frequency input, it's troublesome to manage.
- Learning Outcome:
- kinds of converters employed in HEV and heat unit vehicles.
- to search out the speed victimisation the torque-speed expression.
- to urge to grasp concerning the induction and DC motor and take a look at to search out the most effective choices on the market.