• State
  • Locked Locked
  • Replies 5 replies
  • Subscribers 29 subscribers
  • Views 1177 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DRV8833: About unstable motor current on slow decay mode.

Tao_2199
Genius 5660 points
Part Number: DRV8833
Other Parts Discussed in Thread: DRV8825, DRV8824, DRV8811, DRV8880, DRV8818

Hello,

 

Regarding to slow decay mode on DRV8833, my customer is asking some question.

They have confirmed that  the motor current is unstable and exceed setting current  on slow decay.

(Please refer attached file.)

At first they tried on first decay and mix decay but it happened howling sound on these mode.

At slow decay mode only, it didn’t happened howling sound. So they have been using on slow decay mode.

(Question)

(1) Could you please tell us the possible cause of this behavior(unstable motor current)?

(2) If there is some solution for this behavior, could you please give comment or advice ?

(3) Is it possible to adjust PWM frequency of current control by external?

 Or it is adjusted automatically internal?

 

Regards,

Tao2199

DRV8825_24V_Slowdecay.xlsx

  • 0
    TI__Guru** 114905 points
    Hi Tao2199,

    Sorry for the delayed response. Is this question about the DRV8833 or DRV8824? Assyming it is the DRV8824, we may not be able to determine the cause without the motor.

    (1) Could you please tell us the possible cause of this behavior(unstable motor current)?

    Is the motor loaded when this event occurs? If not please try the following:
    a) add some type of load or damper and try the experiment again
    b) set the motor to a full step position, disable the outputs, then re-enable and capture the waveforms.
    Did the results change?

    (2) If there is some solution for this behavior, could you please give comment or advice ?

    This could depend on the results of above

    (3) Is it possible to adjust PWM frequency of current control by external?
    Or it is adjusted automatically internal?

    It is not possible. The PWM is fixed. If you want to adjust the PWM frequency, the DRV8811 can achieve this. Also the DRV8880 with adjustable off time allows the frequency to change.
  • 0 in reply to Rick Duncan
    Genius 5660 points

    Hello Rick,

    Thank you for reply.
    I asked to my customer about motor driver that they have been using, and they use DRV8825.
    Sorry for confused.

    In this device(DRV8825) case,
    1) About confirmation items from you,
    Will contents be same as your last answer?
    Or we may not be able to determine the cause without the motor?
    2)Similarly to your last answer ,is it impossible to adjust PWM frequency of current control by external?

    Regards,
    Tao2199

  • 0 in reply to Tao_2199
    Genius 5660 points
    Hello Rick,

    Would you let me know the current status of above question?

    Regards,
    Tao2199
  • 0 in reply to Tao_2199
    TI__Guru** 114905 points
    Hi Tao2199,

    1) The contents will be the same as my last answer.
    2) Correct, the PWM frequency cannot be adjusted. If you want to adjust the PWM frequency, the DRV8811 or DRV8818 have this option.
  • 0 in reply to Rick Duncan
    Genius 5660 points
    Hello Rick,

    Thank you for reply.
    I have informed your answer to my customer and when I have update from them, I will inform you soon.

    Regards,
    Tao2199