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DRV10983: DRV10983 repeatly spin for a while then stop

Diba Digital
Prodigy 20 points
Part Number: DRV10983

Hello everybody,

We have the DRV10983 IC and make our PCB board tune a BLDC motor with 8 pins (U, V, W, +5, H1, H2, H3, GND). The schematic of our board is the same as the EVM DRV10983. our BLDC motor is  DFA68M024037-A from Nanotec Co. Its datasheet link is here.

BLDC motor's HALL sensor pins are not connected.

DRV10983 PCB's voltage of V1P8, V3P3, VREG, and VCC is correctly 1.8V, 3.3V, 5V, 24V. All the registers can be correctly read and written through IIC, and their value is stored in EEPROM as a default value or some other value. But I still can't correctly use DRV10983. 

I want to use analog mode to control motor speed. I write these values in the EEPROM:

0x20: 0x0D (according to the datasheet of our BLDC motor, the Resistance Line to Line is 0.25 ohm)

0x21: 0x4F (according to the datasheet of our BLDC motor, the Back-EMF Constant  is 3.75 Vrms/krpm)

0x22: 0x49

0x23: 0x00

0x24: 0xC0

0x25: 0xF7

0x26: 0x88

0x27: 0xB0

0x28: 0xAE

0x29: 0xC9

0x2A: 0x0C

0x2B: 0x0C

After I read back the EEPROM register (0x20~0x2B) and verified it correctly. I think the BLDC motor should spin more and more quickly, and finally spin at a special speed. But actually, the BLDC motor always spins for a while (up to about 0.10 A) and then stops. A few times later, the BLDC motor repeats spin for a while and then stops. This appearance seems like user user5161585's question named "DRV10983-Q1: DRV10983 repeatly spin for a while then stop" and wenjun sun's question named "DRV10983-Q1: Can't control speed, spin from stop to max then repeat". I have changed the register value But the BLDC motor still repeatedly spins for a while and then stops. I checked the registers 0x10 and 0x1E, there aren't any faults.

The following is the voltage across the U pin and the V pin. I'm not familiar with DRV10983 and BLDC motor deeply. please help me How can I solve this problem?

Thanks

regards,

Diba


  • 0
    TI__Mastermind 24415 points

    Hi Diba,

    Did you convert the BEMF constant units from Vrms/krpm to mV/Hz? I would recommend you to check the DRV10983 tuning guide (link below) for tuning guidence. 

    Tuning guide: https://www.ti.com/lit/pdf/slou395

    Regards,

    Vishnu

  • 0 in reply to Vishnu Balaraj
    Prodigy 20 points

    Hi Vishnu,

    Yes, I converted. It is 3.75 Vrms/krpm. It divides to 0.0166 is equal to about 225 mv/hz (1 rpm is equal to about 0.0166 Hz). So, I selected 220 from the BEMF Constant Look-Up Table. Did I convert correctly?

  • 0 in reply to Diba Digital
    TI__Mastermind 24415 points

    Did you also convert voltage from rms to peak? 

  • 0 in reply to Vishnu Balaraj
    Prodigy 20 points

    yes, I also tested 225 mVrms/hz divided by 0.7 is equal to about 322 mv/hz (1 Vpeak is equal to about 0.7 Vrms). So, I selected 322 from the BEMF Constant Look-Up Table. Did I convert correctly? I tested many values but had no effect. even I manually spin the motor and use an oscilloscope to capture the differential voltage waveform between any two phases.

    This picture is a differential voltage waveform between any two phases when manually spin the motor:

    according to the picture, "Te" (in the Tuning guide) is 13 ms, and "Ep" (in the Tuning guide) is about 4 Volt. So, Kt is 13ms multiple to 4V is equal to about 52 mv/hz. So, I selected 51.3 from the BEMF Constant Look-Up Table. Did I calculate correctly? Unfortunately, it has no effect and the motor spins for a while (up to about 0.10 A) and then stops. A few times later, the BLDC motor repeats spin for a while and then stops. what should I do?

    you can see changes in the differential voltage waveform between any two phases video below:

    you can see sinus waveform for a while then stop and repeat again...

  • 0 in reply to Diba Digital
    TI__Mastermind 24415 points

    Hi Diba,

    In your BEMF constant measurement, you should consider the peak voltage of 2V and not peak-to-peak voltage. So, your Kt will be 26 mV/Hz. 

    From the video, it looks like the motor spins in open loop for few seconds and some fault gets triggered. Device waits for 5 seconds and clears the fault after 5 sec and tries to spin the motor again. Can you read the Fault register (address: 0x1E) and check what lock gets triggered? 

    Regards,

    Vishnu

  • 0 in reply to Vishnu Balaraj
    TI__Mastermind 24415 points

    I will close this for now, since I haven't heard a response back. If you want a follow-up, please feel free to create a new thread by clicking "Ask a related question" button located on top right of this page.