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  • doubt on motor speed-current relationship

    dilip8815

    Member

    Updated: Oct 26, 2024
    Views: 1.1K
    i am building a electric car where i am using a DC motor.like any other car this also has a battery. assume the top speed of the car is 80kmph and it consumes X amount of energy from the battery. also assume the car moves about 50 kilometers per fully charged battery. now i have added a gearbox-generator arrangement on the chassy of the vehicle. this is to regenerate power during braking. this is arrangement causes an extra load on the motor.

    Now my doubt is, with the extra arrangement, when the car is speeding, will the motor consume more energy from the battery or will there be a compromise in the speed?
    to be more precise, will the top speed come down to say 70kmph or will the mileage come down to say 40km per fully charged battery?
    how will the motor behave when there is an extra load on it? will it still run at the top speed of 80 by consuming power more than X from the battery (and draining the battery faster) or will the motor consume the same X amount of energy from the battery but run at a speed less than 80kmph?
    what will be the effect of the extra load be on the motor speed?
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Replies

  • lal

    Member • Feb 16, 2010

    I think both the top speed and mileage will be lowered. But we are using a generator mechanism to compromise the mileage drop. And the aceleration would decrease.
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  • KAPILBEC

    Member • Feb 17, 2010

    hey i don't think that there ll be an extra load on motor because it ll feed only the field winding as usual and nothing extra to be served.Yes, the speed ll of course decrease as it undergoes breaking although it may be regener😁ative.
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  • aj_onduty

    Member • Aug 25, 2010

    To increase the mileage by a very small amount, I have a solution on the regeneration side. When the motor is using the power, that is when it is accelerating or running(consuming power), the field excitation for the generator should be disengaged. Now, for when the power to the motor is disconnected, for decelerating or for not running, engage the excitation after a time delay, say 1 or 2 seconds. The free running of the car will give u power. And when you hit the brake pedal, the excitation should be instantly engaged.
    This may not be of much importance for you in the practical side, but I feel this would decrease the power intake.


    If you are driving the car in a hilly area, you can benefit from the generator.
    I should say that you must use the regeneration unit in your car. I feel it has practical benefits,though I cannot prove it to you theoritically.
    I want to get corrections from anyone who things I am wrong. Please correct me.
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