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C2000-GANG: Consultation Regarding OverModulation on DRV8323RH_3SC-F2800137

A B
Prodigy 10 points

Part Number: C2000-GANG
Other Parts Discussed in Thread: C2000WARE

Evaluation Board: DRV8323RH_3SC
MCU: F2800137
Reference Example: universal_motorcontrol_lab_f280013x
Example Path:
...\c2000\C2000Ware_MotorControl_SDK_5_04_00_00\solutions\universal_motorcontrol_lab\f280013x
Observer Used: FAST

image.png

Issue DescriptionWhen setting the parameter USER_M1_MAX_VS_MAG_PU to 0.55f, the motor runs smoothly with stable speed and clean current waveforms.
However, when increasing the parameter to0.576f, the following issues occur:
1. Significant speed oscillation;
2. Considerable increase inDC bus current ripple.

Following the official documentation, I attemptedto enable the overmodulation feature by switching from MOTOR1_OVM_N to MOTOR1_OVM, then rebuilt and flashed the firmware. Unfortunately, this change had no effect—the speedand current issues remain. I have repeated this process multiple times with consistent results.

Questions
I would like to ask the following:

Does the example universal_motorcontrol_lab_f280013x support OverModulation operation?
If yes, could you kindly providea detailed tuning guide or configuration document related to OverModulation?
Thank you very much for yoursupport!

  • +1
    TI__Mastermind 23441 points

    Hi,

    Yes, overmodulation is supported in the Universal Motor Control Lab projects. What speed are you running the motor and testing at? You would have a limit to what the speed may be at where the motor is spinning smoothly. 

    Regards,

    Peter

  • 0 in reply to Peter Luong
    Prodigy 10 points

    Issue Description:
    We are not using the speed control loop,but directly applying a maximum current command (the no-load current is 1A, and we are settingit to20A). When USER_M1_MAX_VS_MAG_PU < 0.55, the motor runs very smoothly. However, as we gradually increase the value of USER_M1_MAX_VS_MAG_PU, we begin to observe speed oscillations and increased current ripple.

    Further Explanation:
    1.We suspect that the high speed might be causing these issues. We are using a low-KV motor, and at USER_M1_MAX_VS_MAG_PU = 0.55, the electrical speed is around 800Hz, corresponding to a mechanical speed of 48,000 RPM, which is still within the safe operating range.

    2.When speed oscillation and current ripple increase, we compared with motor controllers from other manufacturers. Their solutions can reach even higher electrical speeds (up to 1200Hz) at maximum speed, with the high-side switches almost fully on, and their current ripple is lower than what we observe.

    Questions and Request for Support:
    1.There is a macro MOTOR1_OVM in the project. Does this macro control the overmodulation operation? Oris overmodulation automatically handled by the system once USER_M1_MAX_VS_MAG_PU is set to a high enough value?

    2.When reviewing the project code, I noticed that the MOTOR1_OVM macro is disabled by default, while USER_M1_MAX_VS_MAG_PU is set to 0.66f by default. Is there a conflict or inconsistency between these two settings?

    Thankyou for your support and assistance!

  • 0 in reply to Peter Luong
    Prodigy 10 points
    Do I need toenable current reconstruction?
    Do I need to enable voltage reconstruction?
    Are there any special parametersthat need to be set?
    Is there any documentation specificallyguiding modulation techniques?
    Thank！
  • 0 in reply to A B
    TI__Mastermind 23441 points

    Hi,

    The overmodulation flag is not needed when you are adjusting the USER_M1_MAX_VS_MAG_PU, it is overmodulation by virtue of increasing the value to the higher value, this is why you are not seeing the different in changing the OVM flag. This seems like you will need to tune the V/F parameters for open loop tuning, though often it is better to focus on improving the performance of the current and speed control modes since USER_M1_MAX_VS_MAG_PU is not used in the later builds

    Regards,

    Peter