DC motor speed control

Discussion in 'General Electronics Chat' started by mahmoud shendy, Oct 16, 2008.

  1. mahmoud shendy

    Thread Starter Member

    Dec 23, 2007
    Dear ALL...

    I have a DC motor (permanent magnet DC motor), the motor ratings are:

    180VDCV and 8Amp
    it runs at 7200 rpm full speed..

    Now, I want to control this motor speed using PWM..

    what is recommended for switching the armature ON and OFF, MOSFET or BIPOLAR?
    if MOSFET is preferable, using it as LOW-side driver or HIGH-side driver?
    i don't need to reverse the motor direction, but can I use two MOSFET or BIPOLARS running
    simultaneously and the motor placed between them?
    what is the recommended MOSFET driver to acheive this work properly?

    thanx in advance .. SHENDY
  2. mik3

    Senior Member

    Feb 4, 2008
    For switching applications MOS are most widely used. If your MOS is N-channel then you will connect it as a low side driver otherwise as a high side driver. Note that you need to use a diode in parallel with the motor armature to absorb the back EMF induced when the MOS is turned off and to increase the average current through the motor.
  3. Bernard


    Aug 7, 2008
    For the diode, try something like ECG5820 12A, 400V, fast recovery. For FET ,around 15A @ 300V. Check around AAC there have been many PWM ckts listed.