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TMS320F280049C: Distorted phase currents

Mojo23
Prodigy 100 points

Part Number: TMS320F280049C

Hi,

we're having the same phenomena as described in this post:

https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/921979/tms320f28069m-instaspin-distorted-phase-currents-when-using-current-reconstruction?ReplyFilter=Answers&ReplySortBy=Answers&ReplySortOrder=Descending

and getting almost exactly the same distorted phase currents :

Anyone knows what was the solution to this?

we're getting this at low speed, so we're very far from hitting any modulation limit (Mindex~=0.3).

I'm suspecting control gains, but maybe there's something else.

thanks!

  • 0
    TI__Guru** 116790 points

    Did you have a chance run the open-loop labs to verify if the current sensing signals are fine for motor control with close-loop?

    And also make sure that the motor parameters are correct for running the lab,

  • 0
    Prodigy 100 points

    Yes we run in open-loop and both the voltage sensors and current look fine.

    We have also a resolver mounted on another motor, and running FOC with same power HW (different control card, 28379D) is not an issue, so at least we know current sensors are ok.

    I'll do some measurements and post the results from CCS graphs.

    We're also getting the Motor ID functionality implemented now, so hopefully we'll be able to ID soon.

  • 0 in reply to Mojo23
    TI__Guru** 116790 points

    OK, please try to use the motor parameters identified with the board to run the motor. See what happens. Thanks!

  • 0
    Expert 1360 points

    Hi, For information, I have sometimes similar current, especially when I was adjusting Kp/KI. The DAC output on the evaluations kit were very helpfull to check the stability of internal signals.

  • 0 in reply to Manu36
    TI__Guru** 116790 points

    Yes, Tuning Kp and Ki of both speed and current regulators may improve the waveform of the current. The current and voltage sensing signals are more important to the FOC. The current waveform is related to the BEMF shape of the motor as well,