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DRV8307: Problem with LOCKn signal.

Piotr Kaczmarek
Prodigy 40 points
Part Number: DRV8307

Hello,

I have a problem with the DRV8307 driver that I used in my application.

The problem is that when I start the engine, until the LOCKN signal occurs, everything is ok. At the LOCKN signal, the motor will suddenly brake (not completely), then start to accelerate again (LOCKN disappears). The situation is repeated cyclically.

Please help and suggestions.

  • 0
    TI__Expert 4435 points
    Hello Piotr,
    It is possible that you are experiencing a fault. Could you please check the nFault pin signal along with LOCKn signal?
  • 0 in reply to Luis Riveros
    Prodigy 40 points

    Hello Luis,

    Thank you for your answer.

    Yes, I checked this signal - no fault.

    Signals from uK:

    BRAKE = 0

    DIR = 1

    EN = 0

    PWM = 1 (MAX)

    HALL = HALL_U

    Other signals:

    ----------------------------------------------------------------------------------------------------------------------------------------------------------------

    TIME = 10 ms

    HALLOTRONS (yellow - U / blue - V / pink - W)

    LOCK (green)

    ----------------------------------------------------------------------------------------------------------------------------------------------------------------

    TIME = 10 ms

    COILS (yellow - U / blue - V / pink - W)

    LOCK (green)

    ----------------------------------------------------------------------------------------------------------------------------------------------------------------

    TIME = 10 ms

    FAULT (pink)

    LOCK (green)

    ----------------------------------------------------------------------------------------------------------------------------------------------------------------

    TIME = 20 ms

    HALLOTRONS (yellow - U / blue - V / pink - W)

    LOCK (green)

    ----------------------------------------------------------------------------------------------------------------------------------------------------------------

    TIME = 20 ms

    COILS (yellow - U / blue - V / pink - W)

    LOCK (green)

    ----------------------------------------------------------------------------------------------------------------------------------------------------------------

    TIME = 20 ms

    FAULT (pink)

    LOCK (green)

    ----------------------------------------------------------------------------------------------------------------------------------------------------------------

    TIME = 50 ms

    HALLOTRONS (yellow - U / blue - V / pink - W)

    LOCK (green)

    ----------------------------------------------------------------------------------------------------------------------------------------------------------------

    TIME = 50 ms

    COILS (yellow - U / blue - V / pink - W)

    LOCK (green)

    ----------------------------------------------------------------------------------------------------------------------------------------------------------------

    TIME = 50 ms

    FAULT (pink)

    LOCK (green)

    ----------------------------------------------------------------------------------------------------------------------------------------------------------------

    TIME = 100 ms

    HALLOTRONS (yellow - U / blue - V / pink - W)

    LOCK (green)

    ----------------------------------------------------------------------------------------------------------------------------------------------------------------

    TIME = 100 ms

    COILS (yellow - U / blue - V / pink - W)

    LOCK (green)

    ----------------------------------------------------------------------------------------------------------------------------------------------------------------

    TIME = 100 ms

    FAULT (pink)

    LOCK (green)

    This is probably all the signals.

  • 0 in reply to Piotr Kaczmarek
    Prodigy 40 points
    Hi everyone,

    I solved the problem.
    I looked at the graphs I made for Luis and noticed that the polarity of the hallotrons was wrong. Now the engine works well.

    Thank You Luis :)

    I have one more question:
    Is it normal that when the engine locks mechanically, will it fall into vibration?
    Releasing the mechanical lock does not cause the engine to resume operation. This happens to the RLOCK signal (3 s). Then the work is resumed properly (after 5 s).

    Best regards,
    Piotr.
  • 0 in reply to Piotr Kaczmarek
    TI__Expert 4435 points
    Piotr,

    Thank you for following up with your results.
    As for your question, when the DRV8307 detects a motor lock what you describe is normal operation. Rlock is set when there are no transitions from the HALLOUT signals, so you might still need some work on the HALL signals. This behavior is described in detail in section 7.3.11.6 or the DRV8307 datasheet. Thank you