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CCS/Tida-00436: BLDC_Sensorless

Ankush Gupta
Prodigy 20 points
Part Number: TIDA-00436
Other Parts Discussed in Thread: TMS320F28021, TMS320F28035, DRV8312, DRV8303

Tool/software: Code Composer Studio

Support Path: /Reference designs/Technical support help for a specific technical issue with a reference design/

I'm trying to port the BLDC_Sensorless code present in TI's Control suite for TMS320F28035 and DRV8312. The controller I'm using is TMS320F28021 and the driver is DRV8303.

I've been able to run the motor with the ported code but I'm facing some trouble with the SPI communication between the controller and the driver IC. I'm writing in the control registers before the while (1) loop and I'm reading all the 4 SPI registers in the while (1) loop. As soon as I start running the motor, first the correct value is written in the SPI registers but as soon as the motor enters close loop it gives a jerk and the SPI control register 1 is reset to 0x1400 and control register 2 is reset to 0x1800. The nFAULT pin keeps toggling.

The data sheet says that the only condition when the SPI registers are reset is when PVDD_UV occurs but we didn't see any such condition while probing PVDD on CRO.

Another problem I'm facing is in understanding how the code converts the ADC count of the current to a per unit value that is given as reference to the current PI loop.

Can anyone help me with the above problems.

Thanks in advance.

  • 0
    TI__Guru** 114905 points
    Hi Ankush,

    Please examine the DVDD and AVDD regulators.

    Do you use EN_GATE? Setting EN_GATE low also resets the SPI registers.
  • 0 in reply to Rick Duncan
    Prodigy 20 points

    Hi Rick,

    We have examined all the internal regulators but couldn't find any issue in it.

    We have used EN_GATE just once and that too at the time of initialization of the device by setting it high. After that we haven't used the EN_GATE anywhere. We even probed the pin to see if it goes low but it never changed state.

    As when we run the motor at 22V @ PWM  duty cycle of 0.1 we do not see the problem.

     

    But when we run at 22V @ PWM duty cycle of 0.2 or Voltage above 22.4V with PWM duty cycle of 0.1 , the problem is there that the control registers get corrupt and disturbs the operation of DRV8303.

     

    Ankush