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DRV10970: Current operation mode problem

Dima Gregoriev
Prodigy 50 points
Part Number: DRV10970

Hi,

I choose DRV10970 driver for Faulhaber motor EN-1226 (9W).

And I have a problem with current signal form, it's not looks like in you datasheet (see photo).

 

Can you confirm that I use right driver or I have to be changed it.

Thanks.

  • 0
    TI__Expert 6065 points

    The current doesn't look correct.

    I would expect current to be like below:

    Are you running in sinusoidal mode or trapezoidal mode.

  • 0 in reply to Sanmesh Udhayakumar
    Prodigy 50 points
    Hi,
    I run my motor in trapezoidal mode because I need more torque.
    I tried to run in sinusoidal mode and the wave form looks the same but with sinusoidal change of amplitude.
    Looks like I have large current ripple and I don't understand why. Maybe this is motor problem.
    Thanks.
  • 0 in reply to Dima Gregoriev
    TI__Expert 6065 points
    This may be a small-inductance motor, so that's why there is so much ripple. Can you give the specs of the motor, including phase resistance and phase inductance?

    My quick thought is to lower the current ripple, we'd potentially need higher pwm frequency from the driver to the motor phases. The DRV10970 device has 25kHz pwm freq.

    Once I get the motor specs from you, I can give more suggestions.
  • 0 in reply to Sanmesh Udhayakumar
    Prodigy 50 points

    My motor configuration marked with yellow.

    From this specification I see that the inductance is small, so you think that higher frequency will help?

  • 0 in reply to Dima Gregoriev
    TI__Guru 61360 points

    Dima,

    Yes higher frequency should help. Unfortunately the DRV10970 cannot run at higher frequency, but we do have a recommendation for you.

    We would recommend trying the DRV8323RS which can run at higher frequency, there is an EVM available here: http://www.ti.com/tool/boostxl-drv8323rs

    The "R" version has an integrated buck regulator which will generate your 5V or 3.3V board rail from the VIN of around 15V as shown in your scope images.

    This device has three current shunt amplifiers which can be used to read the current through each motor phase if desired, the DRV8320RS does not have these if they are not needed.

    The "S" version is SPI controlled while there is also an "H" version which is hardware controlled if desired.

    Please let us know if this recommendation suits you.

    Regards,

    -Adam