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Inductances in Motors

Hello All,

I have a less complicated question.

I would like to know the Inductances in High Speed and Low Speed motors. ( please do explain in detail). 

Thank you,

Sincerely,

Harsh

  • Harsh,

    I'm not quite sure what specifics you are looking here?

    As per my unbderstanding, motor inductance is not only function  of speed, but also determine by power handling capability, stator slots, air-gap, motor poles etc.  For same pole motors, higher speed motor may have lower inductance with respect to lower speed counter-part but it can generalised across all motor based on speed parameter.

    Best Regards

    Milan-Motor Application Team

  • Hello Sir,
    Thank you for the reply. I am attending a class on Motor Drives. My professor asked a question regarding the Inductances in High Speed Motors. Thank you for educating me that Motor Inductance depends not just on speed but also on variety of factors like Power, Slots, ait gap etc.
    Thank you.

    Regards,
    Harsh
  • inductances will be low to support high speed maximum frequencies. Knowing Rs / Ls gives you an idea on the maximum frequency. Typically the Rs / Ls is ~2x the maximum designed frequency, but in high speed motors (especially in hobby style motors ) they are >> 2x.

    The Ls combined with the flux of the machine also sets the short circuit current, so can be used to design the current handling capability of the motor.

    Flux in RPS / Ls = Short Circuit Current
  • Hello Chris,
    Thank you for the reply.
    It makes sense. The air gap in high speed machines is quite higher compared to low speed machines, to make the inductance smaller. Also thank you for the Short Circuit current info.

    Regards,
    Harsh