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MCF8315C: Issue with MCF8315C1VPWPR Custom Fan Driver Board – Unable to Achieve 480 RPM

ARAVINTHAN T
Prodigy 40 points
Part Number: MCF8315C
Other Parts Discussed in Thread: MOTORSTUDIO

Tool/software:

Hello Team,

          We are working with the MCF8315 evaluation Board (three-phase sensorless FOC integrated MOSFET BLDC motor driver). Using the EVM, we were able to successfully achieve 480 RPM with stable operation.

          However, on our custom fan motor driver board designed with the same controller MCF8315C1VPWPR, we are facing an issue. The motor runs only up to 330 RPM. When we attempt to increase the target          speed to 350 RPM or higher, the controller immediately asserts nFAULT and the motor stops.

We have applied the same register configuration on our custom board as used on the EVM. Despite this, the behavior is different.

Could you please help us understand:

  1. Why the custom board fails to run beyond 330 RPM, while the EVM works fine up to 480 RPM?

  2. What possible hardware or register configuration differences could cause this fault?

  3. Are there specific parameters (like motor tuning, protection thresholds, or layout considerations) we should re-verify on the custom board?

Any guidance on troubleshooting this issue would be greatly appreciated.

EVM BOARD REGISTERS.xlsx

Kindly revert ASAP.

Thanks

Rahil Ahamed.

  • 0
    TI__Mastermind 23602 points

    Hi Rahil,

    What is the fault you see on the custom board?

    What is the current above 330 RPM expected, is thermal pads are designed properly on the custom PCB? Please share the PCB layout if possible.

    Check DC bus capacitance, verify ripple on the VM line.

    Thanks and Best regards

    Venkatadri S

  • 0 in reply to Venkatadri Shantaram84961
    Prodigy 40 points

    Hello Team,

    A. The fault is CONTROLLER_FAULT_STATUS Register.  CONTROLLER_FAULT_STATUS = 0X80040000


    1. 31st Bit CONTROLLER_FAULT is SET.

    2. 18th Bit HW_LOCK_LIMIT is SET.  This is the fault in Custom Board.

    B.  In 330 RPM above expected is 1.5A above. Yes I think thermal pads are designed properly on the custom PCB. I attached below Please verify this,

    TOP & BOTTOM LAYER


              

    TOP LAYER

         

    In Custom board, we tried to increase above 330 RPM the CONTROLLER_FAULT_STATUS Register is SET automatically and nFault error Occurs.

    How to Clear the CONTROLLER_FAULT_STATUS? Any guidance on troubleshooting this issue would be greatly appreciated.

    Thanks and Best Regards,

    Rahil Ahamed.

  • 0 in reply to ARAVINTHAN T
    TI__Mastermind 23602 points

    Hi Rahil,

    PCB layout is good and thanks for reading the controller fault.

    In the JSON file, have you added deglitch time for HW LOCK Limit?  FAULT_CONFIG2->HW_LOCK_ILIMIT_DEG set to min 2uS .

    Also increase the HW LOCK LIMIT if ok to increase.

    Thanks and Best regards

    Venkatadri S

  • 0 in reply to Venkatadri Shantaram84961
    Prodigy 40 points

    Hello Venkatadri,

    We are changed the parameters as per the above, but still the Fault is set. In this we can't increase the HW LOCK LIMIT. Already we set the highest value is  in 3.75A.

    But still CONTROLLER_FAULT_STATUS is set automatically. How to solve the Fault?

    Kindly revert ASAP we are waiting for your reply.

    Thanks and Best Regards

    Rahil Ahamed.

  • 0 in reply to ARAVINTHAN T
    TI__Mastermind 23602 points

    Hi Rahil,

    Can you share JSON file?

    Can you program the JSON to EEPROM, power cycle and confirm if it is return properly and then test again?

    Thanks and Best regards

    Venkatadri S

  • 0 in reply to Venkatadri Shantaram84961
    Prodigy 40 points

    Hello Venkatadri,

    I attached PDF for your reference. I replace JSON file to PDF. Kindly gothrough this and let me know.

    Thanks and Best Regards 

    Rahil.

    2273.EVM BOARD REGISTERS - Copy.pdf

  • 0 in reply to ARAVINTHAN T
    TI__Mastermind 23602 points

    Hi Rahil,

    I will verify this and respond by tomorrow.

    Thanks and Best regards

    Venkatadri S

  • 0 in reply to Venkatadri Shantaram84961
    TI__Mastermind 23602 points

    Hi Rahil,

    I need to copy the PDF every line to GUI, I will verify the register in detail and get back.

    Thanks and Best regards

    Venkatadri S

  • 0 in reply to Venkatadri Shantaram84961
    TI__Mastermind 23602 points

    Hi Rahil,

    I looked at JSON and find it needs improvement.

    1. Buck if you are using resistor, buck closed loop current should be 150mA

    2. Why open loop acceleration is slow and closed loop is 60Hz, if motor can spin at high rate you can increase open loop to say 25Hz/s

    3. Do your motor need peak current of 3.1A? What is the rated current  at mas speed and stall current?

    Can you leverage SmartTune feature provided in the MOTORSTUDIO ver 0.1.30 and tune the motor?

    Thanks and Best regards

    Venkatadri S

  • 0 in reply to Venkatadri Shantaram84961
    Prodigy 40 points

    Hello Venkatadri,

    As per your earlier guidance, we have implemented the suggested changes. The setup is now working fine on the EVM board Only. However, when we use the same register values and parameters on our custom board, it is not working as expected.

    We have verified that all the registers and parameters are aligned with the EVM board configuration. Still, the issue persists only on the custom board

    Kindly go through the attached EVM board data and guide us on:

    1. Which registers need to be modified specifically for the custom board.

    2. Which parameters should be adjusted to ensure stable operation.

    Once we receive your updated inputs, we will implement them on our custom board and run the setup again.

    Kindly revert ASAP.

    Thank you

    Rahil.

    FAN_DATA_EVM.zip

  • 0 in reply to ARAVINTHAN T
    TI__Mastermind 23602 points

    Hi Rahil,

    The configuration is for MCF8316C? The current limits are 8A in HW LOCK limit, ILIMIT is 5A and so on.

    Is it possible to capture any one phase current while running and try to capture when the HW lock limit occurs? May be with 100ms time scale good enough.

    I don't see issue with fault configuration setting, only concern is whether any ground reference issues.

    We will also re check layout, can you point GRN "1" and AGND near the device?

    Since you are able to verify with EVM working properly, I want to verify ground and also phase current (capture with EVM as well)

    Why we need this? If there is any noticeable oscillation at higher speed which can trigger such faults. R, L may not be proper, ground reference as well.

    Alternatively, you can disable Speed loop and test only in torque loop.

    Thanks and Best regards

    Venkatadri S