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Sporadic motor skipping

Shiranga Ariyasinghe
Expert 1145 points

Other Parts Discussed in Thread: MOTORWARE

Hi All, Hi Chris,

We are in a process of building igbt based high voltage, high current traction inverter using TMDSHVMTRPFCKIT solution. Motorware lab5a firmware is used to control the motor with some changes. A resolver is used to measure rotor angle which has connected to TMDSRSLVR kit. After calculating electrical angle, angle data is been sent to motorcontroller using SPI communication. We have added that electrical angle to CTRL_runOnLine and CTRL_runOnLine_User functions. 

We have tested this inverter with 150Vbus and we saw something like this. When we started to rotate the motor, motor was running smoothly. There was no issue with that. But when we increased torque command (Iq_ref) after some torque level, motor sporadically makes a skipping noise. During the noise we see the wave forms below, where the DC bus voltage seems to oscillate. We have a 800uF DC link capacitor as well as sunbber capacitors on the IGBT legs. 

During the DC bus oscillations,we notice that the PWM signal duty cycles  from the c2000 seem to stay static, and after the skipping noise it gets back to normal. And this continues sporadically, increasing the events with higher Torque Commands. 

 

PWM output data from micro controller at fault time

PWM output data from micro controller at fault time

 

Collector- Emitter waveform of a IGBT in inverter at fault time

 

Thank you.

  • 0
    TI__Guru** 119680 points
    have you monitored the inputs and outputs of the Iq and Id current controllers, and the angle being generated from the resolver? I would try to see if you can narrow down the issue to a feedback path.
  • 0 in reply to ChrisClearman
    TI__Mastermind 27240 points

    Hi,

    I suspect the SPI communication being messed up. Would recommend you run the motor with a locally generated position angle instead of the resolver angle from SPI. For sure, the motor will not run in FOC conditions, but atleast it will tell you whether the problem is due to error in any position sensing or not. If it narrows down to SPI communication, then you may need to add some filters in the signal path.

    Let us know what you find.

    rgds,

    ramesh

     

  • 0 in reply to ChrisClearman
    Expert 1145 points

    Chris,

    Sorry for the delayed reply. Iq input is directly given through a eCAB bus. I checked resolver SPI link using a logic analyzer and seems that resolver angle is coming without an issue. 

    But I can not inspect all the registers (ADC results, PWM, etc) inside the micro-controller using watch window because connection with watch window get lost at the moment inverter get contact with high voltage (EMI issue or something may be the reason). I tried to mount SD card with FATs file system to get records in feedback path. But I could not do that.  Can I attache FATs file system with SD card to motorware to debug system ? Are there any examples to do that?  Is there any other method to get data out from micro-controller? 

  • 0 in reply to Shiranga Ariyasinghe
    TI__Guru** 119680 points
    can you solve the connection issue instead? EMI seems the culprit. It is possibly your power supply.

    we do not have examples of logging data to SD card.