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TMS320F280025: Harmonic on FAST output

Manu36
Expert 1360 points
Part Number: TMS320F280025


Dear Support team,

This question is for motor control expert, especially regarding FAST observer.

I use motor control SDK on my own hardware. SW is really closed to the universal_motor_control_lab.

FAST give really good results and up to know, I was abble to tune the SW to improve for my need (regulator tuning, etc...).

But I can see that some internal signal have some harmonic which create some small oscillation on the regulators, let me explain:

-speed from FAST has an harmonic (around x 16 fundamental frequency).

-I can see also this harmonic on Id and Iq IN.

I suppose this is related to the EMF of the motor which is not perfectly sinusoidal.and create a non perfect current.

Is there a way to tune the FAST estimator to try to reduce this?

With best regards.

  • 0
    TI__Guru** 116090 points

    It could be not related to the FAST estimator. You may try to tune the gain parameters of speed and current PI controller, may try to improve the current and voltage sensing signals as well.

  • 0 in reply to Yanming Luo
    Expert 1360 points

    Hi,

    I already try to tune. For me sensing signal are not the issue.

    I just plot the angle estimator output (using PWMDAC) and the phase to phase voltage (differential probe), without powering the motor (spin by hand) and I can clearly see that the harmonic on the angle is synchronised with the distorsion on the back-emf (not perfectly sinusoidal).

    Up to now I have been able to deal with it by implementing some digital filtering but if i can improve it direcly at the source, it will probably be better.

    Regards.

  • 0 in reply to Manu36
    TI__Guru** 116090 points

    You can try to find some of the related papers and try to implement its method. Unfortunately, there is no a reference code for you in current MCSDK.