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DRV10975: Motor current waveform

ACGUY
Guru 11170 points
Part Number: DRV10975

Hello E2E,

Our customer is using the DRV10975 for new product. They are evaluating on them engineering board now.
Please see attached.
Settings are constant speed, same one motor, same one device. Motor current waveform has change. It repeats irregularly.

What is the device doing?

Regards,
ACGUY

  • 0
    TI__Mastermind 24405 points

    Hi ACGUY,

    Thanks for posting your question in MD forum. Is the waveform the phase current of the motor? Waveform doesn't look right to me. Phase current should be sinusoidal. However, this waveform looks noisy with a DC offset. Clearly, the device is not tuned well. Can you share the motor parameters and the EEPROM settings? I would like to review the EEPROM settings.

    Regards,

    Vishnu 

  • 0 in reply to Vishnu Balaraj
    Guru 11170 points

    Hi Vishnu ,

    EEPROM settings are following.

    0x20 0xE9
    0x21 0xD
    0x22 0x39
    0x23 0xCC
    0x24 0x10
    0x25 0xC0
    0x26 0xA4
    0x27 0xB8
    0x28 0x55
    0x29 0xB6
    0x2A 0xD
    0x2B 0xC

    We can't to know the motor parameters. I'll find out soon.

    Regards,

    ACGUY

  • 0 in reply to ACGUY
    TI__Mastermind 24405 points

    Hi ACGUY,

    Thanks for providing the register values. As mentioned, please provide the motor parameters as well.

    Regards,

    Vishnu.

  • 0 in reply to Vishnu Balaraj
    Guru 11170 points

    Hi Vishnu,

    ・ Measured value of resistance between terminals of the motor: 8.5Ω, that is, 4.25Ω per phase
    → Enter 4.23 for Phase to Center Tap Resistance

    ・ Measured value of Kt: 9.171 mV / Hz
    → Enter 9.06 in BEMF Constant (Kt)

    Regards,

    ACGUY

  • 0 in reply to ACGUY
    TI__Mastermind 24405 points

    Hi ACGUY,

    Thanks for the details. I'm still not clear about the waveform that you shared. I see that the frequency of the waveform that you shared is 25 kHz. This doesn't look like motor phase current. It is more likely some random noise. Can you measure the phase current again? You should be able to see a sinusoidal low frequency waveform. Is the device able to spin  the motor with the register settings you shared? If not, then can you check what fault is getting triggered? Fault code can be read from register address 0x1E.

    Regards,

    Vishnu.