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PM Synchronous motor Id-Iq current control

  1. Mar 18, 2015 #1
    Hi everyone,

    I am trying to implement the current control (Id, Iq) of a four pole PM synchronous motor. I am having trouble in making the Iq current follow a set reference.

    115622d1426715693t-pi.jpg

    I had also implemented a cascaded speed control for a dc motor.

    115621d1426715561t-cascaded.jpg

    In that case, I adjusted the gains of the PI controller (inner loop/current loop) by stalling the motor and checked if the motor current followed the set reference current. It worked in this way for the dc motor. I thought of doing the same way for Iq but I am not getting the expected results.

    In delta configuration of the stator, if I make the integral gain to be zero, the motor does not rotate. The motor starts rotating if I increase the integral gain to 1 and the speed increases as I increase the integral gain and reaches the maximum value depending upon the supply voltage.
    If I stall the motor at different speeds, I get different values of Iq, say for 30 rad/s I have a current of 30mA and 60 rad/s, it is 50mA.
    The motor current (Iq) is not following the reference current for any change I am making in the Kp and Ki values

    Is there any other approach to achieve the PI control for both the currents?

    Thanks
     
  2. jcsd
  3. Mar 21, 2015 #2
    Your images can only be viewed with an edaboard account.
     
  4. Mar 22, 2015 #3
    Sorry about that!
    Should have checked the links after posting them..anyways they are below..

    Fig 1

    upload_2015-3-22_13-27-36.jpeg

    Fig 2

    upload_2015-3-22_13-28-0.jpeg
     
  5. Mar 23, 2015 #4
    Have you checked that the basics of your system work, e.g. making sure you can produce a current vector in the stator-fixed reference frame (αβ-components) that follows some reference? If that works, then you can start worrying about the rotor-fixed reference frame.

    In general, if you represent your system as a hierarchy of components, you start at the root, test it through and through, and then you can start building atop of it. In your case, the root could be a sampling system, with the reference-frame transformations built atop of it.
     
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