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DRV8316C-Q1: BLDC motor spins too fast

?? ?
Prodigy 10 points
Part Number: DRV8316C-Q1

Tool/software:

Hello TI engineers.

I am trying to drive a 3-phase BLDC motor using the following hardware.

The DRV8316C-Q1 is set to default and is in 6xPWM mode.

I am supplying 12V from the power supply to rotate a BLDC motor with a rated voltage of 12V, but even when I reduce the duty to 3% with 20kHz PWM, the motor still rotates at a high speed (around 3000rpm).

Could you please tell me what the cause of this is?

Is this because the DRV8316C-Q1 settings are incorrect, or is it due to the motor specifications?

If it is due to the settings, please tell me what settings I should make and how.

Hardware used

Driver IC: DRV8316CR-Q1

Board: DRV8316xEVM Evaluation Module

Motor specs:

Rated voltage (12V), no-load speed (4090rpm), no-load current (140mA), rated speed (3120rpm), rated current (510mA),

If it depends on the settings, please tell me what to set and how.

best regard.

  • 0
    TI__Mastermind 19886 points

    Hey,

    Are you using the TI's GUI for controlling the motor? or your own FW?

    Can you measure the OUTx waveform at 5% duty cycle and 50% duty cycle? I want to check if the commands are going through.

    Best,

    Akshay

  • 0 in reply to Akshay Rajeev Menon
    Prodigy 10 points

    Hello Akshay-san.
    Thank you for your reply.
    I created the software myself.
    I am performing square wave control using a hall sensor.
    As far as I can see on the oscilloscope, the PWM wave with a duty of 5% and the output waveform of OUTx at that time are output correctly in sync.
    I am unable to measure the duty at 50% because the motor stops.
    My guess is that the current may be overloaded.
    Please let me know if there is any other information you need.
    Thank you in advance.

  • 0 in reply to ?? ?
    TI__Mastermind 19886 points

    Hello,

    You are doing sensored trapezoidal control with hall sensors?

    What is the highest duty cycle you are able to get w/o motor stopping?

    When the motor stops can you do a fault read on spi and tell me what faults are getting triggered?

    I would  like to see two sets of waveforms one at the small duty cycle and one at larger duty cycle to compare the difference. I would like to see the OUTx signals of three phases and nfault (trigger on nfault falling low). And a separate waveform where you replace one of the OutX signals with phase current.

    Best,
    Akshay

  • +1 in reply to Akshay Rajeev Menon
    Prodigy 10 points

    Hello Akshay-san.
    Thank you for your reply.
    A bug was found in the software.
    I'm not sure if it's related to this issue, but if the problem persists after you fix it, I'll ask you again.
    Thank you.

  • 0 in reply to ?? ?
    TI__Mastermind 19886 points

    Hello,

    Understood. I am marking the thread as closed for now. Feel free to reopen if the problem persists.

    Best,

    Akshay