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DRV10975: No Motor Fault Showing when reaches open to close loop threshold

Sourav Gupta1
Prodigy 50 points
Part Number: DRV10975
Other Parts Discussed in Thread: DRV8313, MSP430G2553

Hello,

I am running a BLDC motor that is perfectly working on the open loop and could achieve the speed of 204Hz. But, when I enable the close loop, it is showing no motor fault and getting restarted. The error is showing when it reaches the open to close loop threshold. 

I have checked the open loop operation and it is working perfectly.

  • 0
    TI__Mastermind 24405 points

    Hi Sourav,

    Thanks for posting your question in MD forum. DRV10975 measures phase U current and checks if this current is below 140 mA during the open to closed loop transition. If phase U current is below 140 mA, then the device triggers "no motor" fault. I would recommend you to disable "No motor fault" by clearing register address 0x27 bit 7. Please note that with "no motor fault" disabled, the device will still report the fault in register 0x1E but not stop and restart the motor. 

    Regards,

    Vishnu

  • 0 in reply to Vishnu Balaraj
    Prodigy 50 points

    Thanks a lot Vishnu. The no motor problem solved but now I am getting a new error that the lock detection current limit getting triggered when the motor cross the open2close loop threshold. I have changed the acceleration current limit as no limit and the lock detection limit as 3.2A. I have also tried Accel current limit as 1.6A and the lock detection current limit as 3.2A. Does not help. 

  • 0 in reply to Vishnu Balaraj
    Prodigy 50 points

    Also for your information, The motor phase resistance is measured 0.25 Ohms (After dividing with 2) and the kt is 4.2mV/Hz

  • 0 in reply to Vishnu Balaraj
    Prodigy 50 points

    Hello Vishnu, Please have the specification of the motor. I am doubtful about the coil resistance. It is out of the DRV10975 application range? Is it possible that the Lock detection current limit getting triggered?

  • 0 in reply to Sourav Gupta1
    TI__Mastermind 24405 points

    Hi Sourav,

    Thanks for sharing the motor specifications. Unfortunately, none of the devices in DRV10x family can support this motor because of two reasons. This is a very high speed motor with minimum frequency of 1200 Hz (36000 rpm). DRV10x devices can only support up to 1000 Hz. Also, the motor inductance is too low. Minimum recommended motor inductance is 0.07 mH. 

    Regards,

    Vishnu 

  • 0 in reply to Vishnu Balaraj
    Prodigy 50 points

    I am sorry, I have provided a wrong information about the motor speed. The minimum speed is 10000 r/min.

    Please have the full specification of the motor. Could you evaluate whether it can be supported by the DRV10975. If not, could you share some alternate part number from the motor driver section? 

    motor-spec.pdf

  • 0 in reply to Sourav Gupta1
    TI__Mastermind 24405 points

    Hi Sourav,

    Thanks for providing the updated information. This motor has very low inductance and resistance. Minimum resistance and inductance that we recommend for DRV10975 is 0.6 ohms and 0.07 mH. We do not have any integrated control devices that can drive this motor. We have Gate driver + integrated FET devices that can support driving your motor but you will need an external microcontroller. Let me know if you are interested in this solution. 

    Regards,

    Vishnu

  • 0 in reply to Vishnu Balaraj
    Prodigy 50 points

    Hi Vishnu,
    Thank you for your message.
    Yes, I will be interested in Gate driver + integrated FET devices that will support driving this motor. I have a microcontroller on the board. Please suggest some solutions.
    Thank you,
    Sourav

  • 0 in reply to Sourav Gupta1
    TI__Mastermind 24405 points

    Hi Sourav,

    DRV8313 will be a good choice for your application. Here's a reference design TIDA-00274 which gives the complete detail of design
    including its hardware details, jumper configuration, operating procedure to run the BLDC motor using GUI.

    Regards,

    Vishnu

  • 0 in reply to Vishnu Balaraj
    Prodigy 50 points

    Hello Vishnu,

    Thank you very much for providing the information.
    The motor we are using has a maximum RPM of 50000. Can this RPM be achieved by the DRV8313 chip?
    If yes, we are using STM32 Micro-controller unit. Could you share some documents or application notes for coding related support for setting the parameters to run this motor?
    Thanks a lot.
  • 0 in reply to Sourav Gupta1
    TI__Mastermind 24405 points

    Hi Sourav,

    Maximum motor speed depends on the clock frequency of the microcontroller. Reference code using MSP430G2553 can be downloaded using this link. Please check TIDA-00274 for more details. Unfortunately, we cannot provide support to your microcontroller as this is a non-TI part. 

    Regards,

    Vishnu