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DRV8452: Do not work Stall detection function

Daisuke Higa
Genius 3515 points
Part Number: DRV8452

Hi support team.

My customer has asked us regarding stall detection.

The evaluation is performed on a customer-customized board.
Currently we have a problem that stall detection cannot be performed with PM motors.
There is now some distortion in the current waveform.
I think that the torque count value is usually a value other than 0 while rotating at a constant number of revolutions, but it does not change at the maximum value (4095).
I have no idea what is wrong.
When I experimented with stall detection in the EVM GUI, I found that disabling the output caused the torque count value to reach its maximum value (4095).
Also, when the output is enabled and rotation starts, the torque count value becomes an intermediate value after about 2 to 3 seconds have passed.
Is this behavior normal?

Best regards,

Higa

  • 0
    TI__Mastermind 37683 points

    Hi Higa,

    Allow me 24 hours to review your question and get back to you with a reply.

    Regards,

    Pablo Armet

  • 0 in reply to Pablo Armet
    TI__Mastermind 37683 points

    Hi Higa,

    Apologies for late reply. 

    Daisuke Higa said:
    When I experimented with stall detection in the EVM GUI, I found that disabling the output caused the torque count value to reach its maximum value (4095).
    Also, when the output is enabled and rotation starts, the torque count value becomes an intermediate value after about 2 to 3 seconds have passed.
    Is this behavior normal?

    The reason for it is because when the motor is disabled, the BEMF collapses causing the torque count to rise. Torque count is proportional to the BEMF.

    The reason for the unstable torque count during motor start up is because the BEMF of the motor slowly increases until it reached its steady state value. Therefore, the torque value may be unstable during startup. It will stabilize one motor reaches steady state.

    Regards,

    Pablo Armet