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DRV8323R: BLDC run under rated RPM and also create lot of noise

sukhpal singh
Prodigy 70 points
Part Number: DRV8323R

Hi   

  As my BLDC control design is working fine with 50 Watt motors but at high speed, my motor creates a lot of Noise and also its speed is lesser then Rated speed. My motor got overheated after some time. 

regards

Sukhpal Singh 

  • 0
    TI__Guru 65410 points

    Sukhpal,

    Thanks for posting on the MD forum!

    Could you share your schematic?

    Can you check if the power supply is saturating? Sometimes if the power supply cannot provide the instant current that the motor needs, the speed will be limited and the motor may sound different.

    Regards,

    -Adam

  • 0 in reply to Adam Sidelsky
    Prodigy 70 points

    TOP Drv Card MCU V-4.pdf

     

     

    Hi 

      As yesterday i on DSO i find that the first half of my Trapazodial is missing. I am attaching is the screenshot .Please check and let me know  The above image is of Mosfet Gate Signal taken when the motor of  4000 RPM connected. That should be clear Trapazodial.

     

     

     

     


     

     

    the above image is when we run the motor at 50% of speed.

     

     


     

     

    this pic is of Phase voltage when we run the motor at full speed. 

     

    so please let me know. why its noot give a clear trapezoidal wave.

     

    reagrds

    Sukhpal Singh 

     

     

     

     

     

     

  • 0 in reply to sukhpal singh
    TI__Guru 65410 points

    Sukhpal,

    If your BEMF waveform does not look correct it is likely that your HALL sensor inputs are not synced with your Motor phase outputs.

    Please make sure that your motor phase A is connected to pin input A on the board and hall input A is connected to hall input A. Same check for B and C. 

    You can check this FAQ as well: https://e2e.ti.com/support/motor-drivers/f/38/t/845535

    Are you configured in 1X pwm mode via SPI?

    Regards,

    -Adam

  • 0 in reply to Adam Sidelsky
    Prodigy 70 points

    HI

      I have configured it in 6 PWM mode. 

     My back emf wave from is shown below 

    I not able to figure out waveform i saw on DSO. So is it possible for you can give me a brief about that .

  • 0 in reply to sukhpal singh
    TI__Guru 65410 points

    Sukhpal,

    You may have some issue with your commutation code or sequence. 

    Do you have an EVM you can try with your motor?

    Regards,

    -Adam

  • 0 in reply to Adam Sidelsky
    Prodigy 70 points

    hi adam 

      as this commutation code works well on lower RPM motors but only on this high-speed motor we got a problem . Also tomorrow I am going to check it with DRV835 3 EVM board. But i think its not look so. As we only provide PWM to DRV and rest it do its self. So let me  know is drv support high-speed motors .

    regards

    Sukhpal singh 

  • 0 in reply to sukhpal singh
    TI__Guru 65410 points

    Sukhpal,

    The DRV does support high speed motors. I would check that your power supply can provide the immediate switching current and check that your hall sensors are aligned to the phases. Please also check that the phases are connected in sequential order as A-->B-->C.

    Are you planning on programming the SPI of the EVM by yourself?

    Regards,

    -Adam