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MCF8329EVM: MCF8329A MPET Parameter Extraction Issue

Sai Kishore
Prodigy 10 points

Part Number: MCF8329EVM
Other Parts Discussed in Thread: MCF8329A, MOTORSTUDIO, MCF8329HS

Hello,

I am working with the MCF8329A and am facing issues during MPET parameter extraction.

Initially, when running MPET, the motor entered a fault condition and sometimes reported an abnormal Back EMF. To avoid this, I increased the Abnornal BEMF lock threshold (% of expected BEMF)  to 70%. However, even with this change, the motor does not spin at all.

I tested with two different drone motors, but the behavior is the same for both.

                                           image (7).png
After entering  Kp, Ki and manually measured electrical parameters like Rs, Ls, Ke. Motor is directly going to CC. We dont know mechanical parameters properly. So I initialized all the registers to zero and manually run using hardware pot.

image (8).png  
Motor entering to Ke measure mode and keep on estimating back emf even after 5mins. The same happens with 2 different motors. The same happened with mechanical parameters estimation too.

Please review the attached Reg File

Let me know if there are any incorrect settings or if you have any recommendations for resolving this issue? 


Thankyou for your time!

  • 0
    TI__Mastermind 32262 points

    Hi ,

    What is the max speed of the motor which you have entered? If the max speed is lower, then the KE measurement may not work due to low speed, and if the max speed is very high, the device may not be able to run the motor in open loop to the handoff threshold, at which point the device measures the developed BEMF.


    Either one of the above-mentioned reasons can be affecting it.


    The next question is regarding the base current configuration as per the shunt resistor — please verify this on priority.


    I also recommend the MCF8329JHS and leveraging the SmartTune feature available in the latest MotorStudio to auto-tune the motor.

    Thanks and best regards,

    Venkatadri S

  • 0 in reply to Venkatadri Shantaram84961
    Prodigy 10 points

    Hello  ,

    Thank you very much for replying. I tried by changing maximum speed as per your suggestion, MPET is completed. However, I am still facing an issue. While the motor is running, it goes into CC mode. After modifying the Initial Acceleration and Current Slew Rate (A/s) settings, the motor runs only in open-loop mode, and the speed continues to increase until it eventually enters CC mode. It does not transition to closed-loop operation.

    I also tried adjusting the Auto Hand-off and other related settings, but the issue still persists.

    Could you please suggest what might be causing this behavior or recommend any additional settings that I should check to run the motor in stable condition?

    Thank you for your support. I look forward to your guidance.



    Regards,
    Sai Kishore.

  • 0 in reply to Sai Kishore
    TI__Mastermind 32262 points

    Hi Sai Kishore,

    I will get back to you with more details.

    Thanks and best regards,

    Venkatadri S

  • 0 in reply to Venkatadri Shantaram84961
    TI__Mastermind 32262 points

    Hi Kishore,

    I missed getting back to you earlier. Could you confirm whether the issue still persists? If so, could you share the JSON layout? Also, have you considered evaluating the MCF8329HS?

    Thanks and best regards,

    Venkatadri S