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DRV8889-Q1: There is a lot of vibration when driving the 24BYJ48 motor

Annie Liu
Genius 10295 points
Part Number: DRV8889-Q1

Hi Team,

When the customer uses DRV8889Q1 to drive a 24BYJ28 (phase resistance 450 ohms, step angle 11.25°) motor, he finds that the noise and vibration are very large. He has tried micro stepping from 1/2 to 1/256, and also tried attenuation mode, but it is no improvement. However, when driving motors of the same size (diameter 24mm, 15 ° step angle, phase resistance 20 ohms), the noise and vibration are very small. 

Is it DRV8889Q1 not suitable for driving stepper motors with high phase resistance or other reasons? (It has been confirmed that SPI communication is normal and STEP pin frequency is normal)

Best Regards,

Annie 

  • 0
    TI__Mastermind 44265 points

    Hi Annie,

    Thank you for the E2E post. The phase winding resistance DCR of 450Ω is very high like you suspected. What is the supply voltage and IFS setting used? Customer must ensure the supply voltage VM is greater than DCR x IFS else current regulation will not be operational because the target IFS will never be reached at lower voltages and result in winding current distortion causing noise and vibration. Can we get current waveforms at 1/2 step, 1/8. 1/32 and 1/256 step modes for analysis. What decay modes were used for testing? With this high DCR customer can try all the DECAY modes to see which mode is suitable to get minimum distortion of the current waveform. 

    Regards, Murugavel

  • 0 in reply to Murugavel4637
    TI__Genius 10295 points

    Hi  Murugavel,

    The power supply voltage is 12V. IFS=46.8mA. The customer has tried all DECAY modes, and the INCREASING_SLOW_DECREASING_SLOW vibration performance is the smallest.

    Best Regards,

    Annie 

  • 0 in reply to Annie Liu
    TI__Mastermind 44265 points

    Hi Annie,

    This is a very low IFS current, only about 3% of the full-scale value of the DRV8889-Q1 capability. So current accuracy will take a big hit - please refer the datasheet on Itrip current accuracy.

    That said lets do a basic analysis of the DC conditions for this motor. At 12V supply and 450Ω winding resistance DCR the maximum possible current through the winding at steady state is V/DCR = 12/450 =  26.67 mA which is significantly less than the target IFS of 46.8 mA. Therefore the motor is running starved with no current regulation. Hence the vibration. 

    For this motor to achieve 46.8 mA the supply voltage VM must be > 21V, at least 24V or so. As the motor spins there will be back EMF to overcome. This will increase the voltage requirement to 28V or even 33V. DRV8889-Q1 can support up to 48V operation. 

    Is it possible to use higher VM supply to > DCR x IFS? "Can we get current waveforms at 1/2 step, 1/8. 1/32 and 1/256 step modes for analysis." This is not necessary for 12V as the problem is well understood. 

    Can the customer use lower DCR motor? Please note Stall detection will not work for such high DCR. We recommend a DCR or around 10Ω. Perhaps it could work up to 20Ω or so.

    Regards, Murugavel