to vary the speed of dc motor without varying its speed

Discussion in 'General Electronics Chat' started by narinder kaur, Feb 19, 2016.

  1. narinder kaur

    Thread Starter New Member

    Feb 19, 2016
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    Hi,i am an engineering student i want to vary the speed of a dc motor without varying its power. Plzz help me!!
     
  2. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    First off you may wish to correct this thread's title;)

    The required input power will be a function of AV (i.e. 'speed'), load and efficiency --- I'm uncertain as to your meaning with 'not vary the power'...:confused:

    IOW -- More info please!:)

    Best regards
    HP:)
     
    Last edited: Feb 19, 2016
  3. crutschow

    Expert

    Mar 14, 2008
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    Plzz explain your problem better (whatever plzz means :confused:).
    What type of dc motor?
    You can vary the speed of a shunt-field dc motor by varying the field current.
     
  4. hp1729

    Well-Known Member

    Nov 23, 2015
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    Vary the burden as well.
     
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  5. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    FWIW I'm guessing the OP's intent is that he/she wishes to vary the AV sans 'static' adjustment of the feed EMF --- Still, who knows...:confused::rolleyes:

    Best regards
    HP
     
  6. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,993
    745
    Sounds like they want to alter the speed without altering the voltage or current through the motor, o_O

    Its a job for Super-hamster!!! :D
     
    Last edited: Feb 19, 2016
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  7. Jonathan Durrant

    New Member

    Jul 5, 2015
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    Pulse width modulation allows you to control the 'speed' of a motor without changing the voltage by changing the duty cycle - but in an AC setting. If you use an ac power source and a filter circuit (Google is your friend) to prevent it from dipping below 0V, you might have some luck.
     
  8. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    @narinder kaur -- Pursuant to the above - Please consider, for instance, a 'phase control' circuit but employing an SCR (as opposed to a triac) as the power switching device... Be advised, however, that a (monopolar) PWM controller is the standard (and, in most applications, optimal) approach...

    Best regards
    HP
     
  9. SLK001

    Well-Known Member

    Nov 29, 2011
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    The OP probably means "how do I vary the speed of a DC motor without varying its torque". One word: Pulse Width Modulation.
     
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