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DRV10970: High current 3-phase sensored DC motor controller

Kash Olia
Genius 3215 points
Part Number: DRV10970
Other Parts Discussed in Thread: DRV10983, DRV8304, DRV10987,

Hello,

I purchased DRV10970EVM to test my 3-phase sensored DC motor and it worked for couple of seconds and then the on-board fuse popped up and it stopped working. There was no load on the motor and I think the internal voltage regulator which produces VINT for Hall sensors was damaged. I was using three 1.5 kohm resistors to create VINT/2 for negative hall sensor inputs (my motor uses Hall IC) and the sensors need pull-up resistor so I also used three 1.5 kohm resistors to pull them up, so by knowing the fact that the internal voltage regulator cannot provide more than 20mA (based on the datasheet), I guess I damaged it. 

The board was purchased for test purpose only, however I know I know I need a higher current motor controller to use in my design. I'm running my motor at 12V input supply to generate 22 oz-in of torque. The below graph shows it would draw more than 2.4A @ 36V to generate 22 oz-in of torque. I searched the TI motor controller directory and couldn't find a motor driver that can provide that much current. Does TI offer a controller that meets this requirement? If not, I'd assume I need to use a pre-driver and power MOSFETs to meet the requirements. 

Thanks,

  • 0
    TI__Mastermind 19720 points

    Hi Khashayar,

    That does not make sense to me that the fuse would be blown because of the >20mA being drawn for the hall sensors. The fuse would be blown if the hall sensors were incorrectly connected or miss places. Can you use the section 9.1 of the datasheet to ensure you hall sensors were connected correctly?https://www.ti.com/lit/ds/symlink/drv10970.pdf 

    The DRV10970 will not be able to provide the 2.4A that you need. You might want to check out the DRV10987 and the DRV10983 if you want to use sensorless devices. If you need a discrete driver you should check out DRV8304.

    Regards,

    Michael

  • 0 in reply to Michael.Walker
    Genius 3215 points

    Michael,

    I'm not sure if the hall sensors are misplaced as the motor spun for couple of seconds with different duty cycle. I'll check the hall sensors with oscilloscope and let you know. 

    Regarding the high current motor driver, If I want to use sensorless devices I would need to use BEMF technique to control them, is this right? 

    Thanks,

     

  • 0 in reply to Kash Olia
    TI__Mastermind 19720 points

    Hi Kash,

    The DRV10987 and the DRV10983 handle the sensorless control for you all you have to do is program your motor parameters into the motor driver and tune the motor startup and it should spin your motor.

    Regards,

    Michael 

  • 0 in reply to Michael.Walker
    Genius 3215 points

    Sounds good, I'll read through the datasheet to understand the theory of operation.

    However, I guess I need something at much higher amperage as 2.4A is required when the system is running at 36V. At 12V supply voltage, I need to triple the current draw. 

  • 0 in reply to Kash Olia
    TI__Mastermind 19720 points

    Hi Khashayar,

    The motor should require only 2.4A at 12V to achieve 22 oz-in. a BLDC motor should have a constant current torque relationship no matter the voltage applied. The motor will have different max speeds dependent on the voltage applied to the motor and the BEMF.

    Here are how the graphs should be:

  • 0 in reply to Michael.Walker
    Genius 3215 points

    Michael,

    I really appreciate your help. No it makes sense. 

    Thank you!