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DRV8350H-EVM: DRV8350 EVM sensorless control developed board debug problem

Part Number: DRV8350H-EVM
Other Parts Discussed in Thread: MSP430F5529

 Hello.

I have designed a new developed board. It can run in the sensored control algorithm. but during  the sensorless controled algorithm, It can run several circles but eventually it stopped ,

I just followed the sensorless controled instructions from below and adjusted the parameters . at last , It still can not run normally. So How to tune motor parameter precisely and finally run the motor?

DRV8350x-EVM Sensorless Software User's Guide (ti.com)

From TI schematic of the DRV8350H-EVM, these capacitors are DNP, but in my schematic it is populated. Would it influence the voltage acquisition so influence the motor run in sensorless control algorithm?

Waiting for your answer.

Best regards,

Scaler_cao

  • Hi Scaler,

    These caps are good in that will help filter out any high frequency noise on the ADC lines to reflect accurate phase and bus voltage feedback. I would recommend adding these for improved ADC accuracy. 

    The sensorless trapezoidal control algorithm for DRV835x with the onboard MSP430F5529 is not very robust for the EVM. Can you ensure that you are not hitting any faults upon startup? Does the motor you are trying to use a trapezoidal motor? 

    Thanks,
    Aaron

  • hi, I feel sorry to click the wrong place to confirm the answer. But actually It does not solve my problem.

    1.The motor is trapezoidal motor.

    2.during startup, there is no fault. The motor can run in several circles , but then there are some faults occurs. the motor stopped and after several seconds the motor re-start because of the firmware inside the MCU. so, this will repeat but will not continues to turn.

  • Hi Scaler, 

    I'm assuming you're using sensorless trapezoidal commutation. Since you are using the DRV8350H-EVM, can you try using the DRV8350H-EVM GUI? If so, can you see what type of fault condition it gives so we can determine if its a software fault or an nFAULT signal from the DRV8350H?

    Sometimes a software current limit can be hit when using firmware or GUI, please check to ensure this is not the case. Also check other parameters from the Sensorless User's Guide to ensure you are not using too fast of a duty cycle and an appropriate startup method (Align, IPD, etc.).

    Thanks,
    Aaron

  • yeah, I have a try. It indicated a fault of UNKNOW FAULT.

    I'll have  a try of slower duty circle and reply for you.

  • Hi Scaler, 

    Please let me know what progress you have made once you conclude testing. 

    Thanks,
    Aaron

  • Hi,

    It still stopped when run several circles. I have tried 30% ,35%,40%,50%,60%,and 100% duty circle, it all runs several circles and then stopped. 

    I just want to know  If it is software problem because It do not need RESET when using the sensorless algorithm. But  using sensored algorithm it need RESET every time.

    So what I mean is that sensored algorithm has some problem .

    actually, I want to use the sensored algorithm. But I can not RESET everytime.

    What's the problem? the video motor run when using sensorless algorithm just in below.

    Waiting for your answer.

    Best regards,

    Scaler_cao

  • Hi Scaler,

    This is the sensorless software from the EVM, right? I don't think its a SW issue, although the sensorless startup method is not great in DRV835x EVM. 

    Can you please check the gate drive current settings (IDRIVE) by setting the right resistor? Make sure you are using a low gate drive current setting by selecting a low gate drive setting on the EVM. It is currently configured for 3x PWM mode and 150mA source/300mA sink. You may need a lower setting in hardware. 



    Thanks,
    Aaron

  • hi Aaron,

    Yeah , that's my schematic below. From TI  schematic   of DRV835x EVM  the mode is 3×PWM. But the sensored and sensorless algorithm is 6×PWM. So is it  a fault and should I change the schematic of my developed board?

    So what you mean is delete the R22   47ohm resistor and  directly tie the pin of MODE to GND and follow the datasheet like below?

    2.The source and sink current is like below.

    So what you mean is I tied the 18K ohm resistor  to the AGND in the pin of the IDRIVE and have a try? The source and sink current only influence the rate of the open and close of the MOSFET.

    3.Finally, all above you just talk to the sensorless control algorithm? right ?

    Thank you for your patience and wait for your answer.

    Best regards, 

    Scaler_cao.

  • Hi Scaler, 

    Your statements before are correct, please switch the H/W resistor to 6x PWM mode and change the IDRIVE settings to lower values to see if that helps lengthen the slew rate. It is important to try and detect what the fault condition is that is causing the sensorless control algorithm to stop.

    Does the nFAULT LED turn on or nFAULT go low when it stops on the DRV8350H? If so, we need to try and determine what the fault may be my monitoring the VDS and VGS waveforms of the MOSFETs to look for potential overcurrent, gate drive faults, etc. If not, is there potential software faults occurring, such as a software overcurrent fault that is preconfigured?

    Thanks,
    Aaron

  • Hi Aaron,

    1.Ok, I'll have a try. but I do not have 18k ohm resistors in hand. maybe tomorrow I 'll buy some and reply for you.

    2.The nFAULT LED does  not  turn on every time when it stops on the DRV8350h.

    3.I have not checked the overcurrent fault  that is preconfigured.

    I did not change the main parameter of the sensorless control algorithm compared with the TI original firmware. I only changed the motor fundamental parameters.

    Finally, can you please help me to solve the sensored control algorithm in another thread. Why every time It need RESET?

    Waiting for your answer.

    Best regards,

    Scaler_cao 

  • Hi Scaler, 

    We are not sure about why RESET is needed, it is likely to have to deal with the firmware of the GUI or something related to SPI-by-wire. The BLDC team is not in charge of the GUI firmware, you may need to ask the MSP430 team for further assistance.

    Can you remove the switch and just short it to ground to bypass reset?

    Thanks,
    Aaron