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TMS320F28379D: MCU Reset

Prince Dany Marapatla
Prodigy 15 points

Part Number: TMS320F28379D

Hello Forums,

I am testing an IPMSM motor control setup using a 48V DC power supply and a dynamometer setup.

Test configuration:

  • DC supply: 48V

  • Motor under test controlled in torque mode

  • Dyno servo running in speed mode at 500RPM

  • Controller: TMS320F28379D-176ptpt

Observed behavior:

  • System works normally up to 48Nm torque command.

  • When torque command is increased to 49Nm, the controller reports DC bus undervoltage fault and then resets.

Additional observations:

  • Reset happens immediately after undervoltage detection.

  • At lower torque values system is stable.

  • DC bus voltage appears to collapse momentarily during the event.Ti_Forums.png

  • From above image Id is at -265 , Iq is at 300 , Torque changed to 49Nm from 47Nm, Error Flag indicates DC bus under Voltage Fault.

Ti_Forums1.png

I would like to understand:

  1. What could cause the DC bus undervoltage only above this torque threshold?

  2. Is the power supply current limit or response time likely causing the reset?

If any information required from my end let me know.

Any guidance on debugging steps would be very helpful.

Thank you.

  • 0
    TI__Expert 8330 points

    Hi Prince,

    This looks more like a system-level power stage / DC bus collapse issue than an MCU reset issue by itself.

    The key point is that the issue appears only when the torque command is increased from around 47 Nm to 49 Nm. At that point, the commanded current increases enough that the inverter/motor draws a large transient current from the 48 V supply. If the supply cannot provide that peak current, or if its current-limit response is slow/aggressive, the DC bus can momentarily collapse. The software then correctly detects a DC bus undervoltage fault. Please confirm the current limit setting of the 48 V supply. At high torque, the input current can increase sharply, especially during transient torque steps.

    Another point to check is that long supply cables, insufficient bulk capacitance, or high ESR/ESL in the DC-link path can cause a sharp voltage dip during high current demand.

    One test you can do to verify whether this is a real MCU reset or a software restart after fault, is that yo can check the reset cause register after the event to confirm whether the device is actually reset by hardware, watchdog, XRSn, brownout, or whether the application is restarting due to software handling.

    Best Regards,

    Masoud