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DRV8884: Humming noise coming when stepper motor not running

JIGAR PATEL2
Intellectual 615 points
Part Number: DRV8884

Hi,

I am using 12V / 300mA unipolar stepper motor which is driven by DRV8884 driver IC with 12v supply.

Settings of driver IC is as below:

1) M1 = 0, M0 = 1, 1/16 micro stepping 

2) TRQ = 0, current scaler to 100%, (no current scaling)

3) DECAY = 15 kΩ to GND, Mixed decay: 30% fast (increasing as well as decreasing)

4) RREF = 100 kΩ to GND, 300mA current set

when stepper motor is running, there is not any problem in all circuit as well as in stepper motor.

stepper motor is running very smoothly without making any kind of noise. It works perfectly.

Here i want to take two cases when stepper motor is not running.

1) 

when stepper motor is not running,

ENABLE pin is low, i.e. MOSFET switch (output driver) is disable.

nSLEEP pin is low, driver ic in sleep mode.

when we want to run stepper motor , then first we logic high above two pins then move the stepper motor, then again logic low above two pins.

in this case , stepper motor is not making any kind of humming noise in both running & not running condition.

2)

when stepper motor is not running,

ENABLE pin is high, i.e. MOSFET switch (output driver) is enable.

nSLEEP pin is high, driver ic in wake up mode.

in this case when stepper motor is running, there is not any kind of noise, stepper motor runs perfectly,

but when stepper motor stops moving, we get humming sound of each time different intensity, some times loud , some times slight .

I want to solve this issue of humming sound.

kindly, help me to solve the issue.

regards,

jigar

  • 0
    TI__Guru 56650 points

    Jigar,

    When the motor is stopped with nSLEEP and Enable pin high, DRV8884 still provides the current to the motor according to "Table 3. Microstepping Relative Current per Step". The winding current ripple could causes the motor mechanical vibration.

    Would you set different decay mode when the motor is stopped?

  • 0 in reply to Wang5577
    Intellectual 615 points

    Hi Wang Li,

    Thanks for your guidance.

    I have tested all four decay modes.

    in which last decay mode ( 2.9 V, Can be tied to DVDD  -> slow decay mode for both increase / decreasing steps) has the lowest noise & vibration.

    Should I go for this decay mode? I mean does it affect on stepper motor holding torque or its running power capability?

    Is there no way to remove complete noise / vibration of stepper motor without making driver ic's MOSFET Off(Enable pin)?

    Regards,

    jigar

  • 0 in reply to JIGAR PATEL2
    TI__Guru 56650 points

    Jigar,

    In general, slow decay would give minimum ripple current. That is why you have less noise on holding position. Since the slow decay has less ripple current, the winding current may be more close the current regulation target if the winding current isn't over driven in Tblank time.

    Holding mode and running mode may require different decay mode. We have to check the current waveform the make decision.

    "Is there no way to remove complete noise / vibration of stepper motor without making driver ic's MOSFET Off(Enable pin)?"

    If we can hold the motor at an electrical angle of 0°, 90°, 180°, or 270, I would think we can get less noise because one phase current is zero no switching, no noise; another phase current is at peak and the ripple current should not cause much mechanical vibration.

  • 0 in reply to Wang5577
    Intellectual 615 points

    Hi Wang Li,

    Thanks for your brief explanation.

    I will go through the action that you have pointed out..

    Regards,

    jigar