Electric Motor Speed Control

Discussion in 'General Electronics Chat' started by friskyy, May 21, 2011.

  1. friskyy

    Thread Starter New Member

    Mar 27, 2011
    13
    0
    Hi

    What is the relationshipp between motor speed and average value of the armature input voltage, in a small electric motor controlled by Pulse-Width-Modulation( PWM) ?

    Is it correct that by increasing the duty cycle of PWM ( the average time the motor is switched on) , we can only increase its average speed. But if we want to increase its maximum speed possible, we have to increase the armature input voltage, because Angular Velocity (w)= Vinput/(k*magnetic flux)?
     
  2. PackratKing

    Well-Known Member

    Jul 13, 2008
    850
    215
    A[ny] motor has a maximum speed, based on rated voltage and drawing a "normal" current......a narrower PWM will control speed -- overvoltage, will only cause it to complain loudly, and release its magic smoke. :D
     
  3. friskyy

    Thread Starter New Member

    Mar 27, 2011
    13
    0
    Hi

    So, this means that if we want to achieve a higher maximum speed we need a motor with higher max rating. Say, 18V Motor will be able to do 300rpm without overheating? Then the relationship w=Vin/machine constant* magnetic flux gives us the max possible speed and the duty cycle dictate if this speed is going to be achieved?
     
  4. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
    348
    You can't go by rated voltage alone when looking at a motor. The way it is wound and the strength of the magnets ultimately make the rated speed determination. You need to look at all the posted ratings.
     
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