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Do not find PMSM decoupling realization in the lab demo

bin gao1
Intellectual 270 points

Other Parts Discussed in Thread: MOTORWARE

Hi,

  From manual, we undetstand we should use Decoupled PI Controllers for a PMSM. However, I check lab demo, e.g., in lab 4, we only find PI controllers and decoupling (as below picture) is missing.

  Is my observation is right ? Or I have wrong understanding.

  Thanks in advance

for.

  • 0
    TI__Guru** 119680 points

    we do not show a code example in the MotorWare labs, but you can add your own. cross coupled current controllers work well, especially for motors with additional saliency.

    we will probably add an example in 2015.

  • 0 in reply to ChrisClearman
    Intellectual 270 points

    Chris,

        Thanks for your quick response. Pls help clarify my understanding

    a) For high performance servo system, add decoupled section will help achived better performance

    b) Is SPM motor and IPM motor using same flow chart( algorithm ) showed in Figure 11-19 of our manual spruhj1e? If not, what's the difference ?

    Thanks in advance

  • 0 in reply to bin gao1
    TI__Guru** 119680 points

    a) I don't believe this is the case no. you'll see better servo performance by running your speed and position loops faster (and current loop fast enough)

    b) in the existing examples we only show an Iq and Id based current control system. you can cross couple this system for both salient and non-salient, but you will see a bigger difference with the highly salient motors. you can further increase the performance for salient motors by updating the Ls values used by FAST at different loads to produce the best estimation for the rotor flux angle used in the control loop.

  • 0 in reply to ChrisClearman
    Intellectual 270 points

    Chris,

        Thanks for your help & answer. Realy appreciated.

       Therefore, SPM motor & IPM motor used same equation (showed in the used guide), right ?

       Also, what is bigger difference with the highly salient motors ?

       Thanks in advance.

  • 0 in reply to bin gao1
    TI__Guru** 119680 points

    bin gao1 said:
      Therefore, SPM motor & IPM motor used same equation (showed in the used guide), right ?

    I wouldn't state it this way.

    The example code all shows an FOC example where the Iq and Id currents are controlled independently with simple Iq_ref and Iq_fdbk, etc.

    the control doesn't change for any motor construction.

    if you are using a salient motor you have the capability to load to the FAST Estimator different Ls_d and Ls_q under different load conditions (when the Ls_d and Ls_q values change). This improves the estimations from FAST for these motors under these conditions.

    bin gao1 said:
    Also, what is bigger difference with the highly salient motors ?

    salient motors are constructed differently, with the rotor magnets buried at different locations in the iron or in slots around the rotor. This gives an assymetrical magnetic field when viewed by the stator.