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DRV8301-69M-KIT: The motor speed cannot go up under load

F.F
Genius 3095 points
Part Number: DRV8301-69M-KIT


Dear team:

Using the package drv8301-69m-kit, after identifying the parameters of the compressor, it is found that the speed of the motor of the compressor can not go up in the case of load, while the motor can stabilize normally in the case of no load. How to solve this problem, I use the lab05b program.

Best regards

  • 0
    TI__Guru** 115500 points

    1. Increase the maximum torque current by changing the "USER_MOTOR_MAX_CURRENT" in user.h.

    2. Check if gMotorVars.Vs is close to "USER_MAX_VS_MAG_PU" by adding below in updateGlobalVariables_motor(). If yes, that means the dc bus is not enough for high speed with load, you need to check the specification of the motor whether it's a low voltage motor for DRV8301-kit.

    // read Vd and Vq vectors per units
    gMotorVars.Vd = CTRL_getVd_out_pu(ctrlHandle);
    gMotorVars.Vq = CTRL_getVq_out_pu(ctrlHandle);

    // calculate vector Vs in per units
    gMotorVars.Vs = _IQsqrt(_IQmpy(gMotorVars.Vd, gMotorVars.Vd) + _IQmpy(gMotorVars.Vq, gMotorVars.Vq));

  • 0 in reply to Yanming Luo
    Genius 3095 points

    Dear Yanming:

    I set "USER_MOTOR_MAX_CURRENT" to 9A. The rated voltage of the compressor is 48V. The normal working current should be less than 9A. With load, the input power can also reach about 48V, 6A.

    According to your prompt, add the corresponding code and observe it as USER_MAX_VS_MAG_PU (0.5). Under no-load condition, the experimental results are slightly smaller than 0.5.

    I think the development kit has the driving power to drive the compressor. Do you need to consider the correctness of compressor parameters, which affects the start-up of the compressor on load?

    Best regards

  • 0 in reply to Yanming Luo
    Genius 3095 points

    Dear Yanming:

    Wait for your reply.

    Thank you.

  • 0 in reply to F.F
    TI__Guru** 115500 points

    What is gMotorVars.Vs value during the motor is running with the load as you mentioned? If the value is close to _IQ(0.5), you have to increase the dc-bus voltage. 

    You may check "ctrlHandle->pid_Iq" and "ctrlHandle->pid_spd" to look if the fbackValue is always less than revalue. If yes, that means the maximum current or the input voltage is not enough for high speed running with the load.

    Could you please post some current waveforms and the specification and parameters of the motor if you still have an issue on this topic?

    Btw, please set the format if these variables to _IQ(24) by right-clicking the variable in "Expressions" and selecting the Q-Values to Q-Values(24).