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DRV8350H-EVM: Help with DRV8350 Input Motor Parameters Tuning - Open Loop Errors

Ramya R
Prodigy 10 points
Part Number: DRV8350H-EVM

Tool/software:

Hello,

I am encountering issue while tuning the input motor parameters.

I have given motor voltage as 24V and speed as 23000RPM. In open loop acceleration control, for Acceleration Rate I gave as 50Hz, for Acceleration Stop Range = 10,000 MHz and Acceleration Velocity Interval = 10,000 MHz. If I try to enable the motor I am getting error in tuning the open loop parameters. Could you pls provide me clarification to encounter this issue?

Thanks.

  • 0
    TI__Genius 12231 points

    Hi Ramya, 

    Thank you for posting to our forum! 

    Can you provide additional details about the motor you are using in this setup?

    This will help us as we look into the matter. 

    Best Regards, 

    -Joshua

  • 0 in reply to Joshua Maize
    Prodigy 10 points

    Hi Joshua,

    Thank you for your response.

    I have attached a file that contains the motor specifications that we have used for your reference.

    Thanks,

    -Ramya

    ECI-038-020 18V PC.002.pdf

  • 0 in reply to Ramya R
    TI__Genius 12231 points

    Hi Ramya, 

    Thank you for information. I will let you know if there is anything further needed. 

    Please look forward to a follow-up response after review this week.

    Best Regards, 

    -Joshua

  • 0 in reply to Joshua Maize
    Prodigy 10 points

    Hi Joshua,

    Just checking in to see if there are any updates or further details on the open-loop acceleration parameters.

    Regards, 

    Ramya R

  • 0 in reply to Ramya R
    TI__Genius 12231 points

    Hi Ramya,  

    I apologize for the long delay. 

     Is this fault thrown immediately when enabling the device,  or only when trying to spin the motor?

    Can you first check to ensure the IDRIVE resistor hardware setting is configured to the lowest setting wirh the proper hardware component. 

    Then for the motor velocity travel and acceleration,  decrease the current values to their lower to middle-range values to observe if the tuning fault is still apparent compared with higher settings. 

    Best Regards,

    -Joshua 

  • 0 in reply to Joshua Maize
    Prodigy 10 points

    Hi Joshua,

    Thank you for getting back to me.

    We are running the motor in Sensorless mode and we are encountering a stall fault when trying to spin the motor. We have also experimented with lowering the motor phase current limit, but the motor runs for short period before showing a stall fault, then starts running again and throws fault repeatedly.

    I have attached a screenshot of the current parameter settings. 

    Could you please help us resolve this issue?

    Regards,

    Ramya R 

  • 0 in reply to Ramya R
    TI__Mastermind 26546 points

    Hi Ramya,

    Thanks for the update! Joshua is out of office right now but should be able to get back to you next week with a response.

    Regards,

    Anthony Lodi

  • 0 in reply to Anthony Lodi
    Prodigy 10 points

    Hi Anthony,

    Thanks for the update.

    As this issue is high priority for us to resolve, Is there anyone else who could assist in Joshua's absence?

    Regards,

    Ramya R

  • 0 in reply to Ramya R
    TI__Mastermind 26546 points

    Hi Ramya,

    Unfortunately there are quite a few team members that are out of office this week so will need to wait for Joshua to come back for a detailed review. In the meantime, I would recommend watching the following video as it gives more insight into sensorless motor control: https://youtu.be/S28P3ZTD9ws?si=SFEaFLPBULIM7hDo

    If the stall condition is occurring during open loop acceleration I would try decreasing the acceleration rate and increase the stall detection timer threshold. If the commutation pattern is being applied too quickly in open loop, the rotor can lose position and stall. 

    Additionally, you may try increasing the back-EMF threshold at which it switches from open loop to closed loop.

    Regards,

    Anthony Lodi

  • 0 in reply to Ramya R
    TI__Genius 12231 points

    Hi Ramya, 

    Thank you for your patience in my absence. 

    Do you have any comment on the initial feedback Anthony has provided? Can you observe the behavior when increasing the stall detection timing parameter while decreasing the acceleration and motor speed? 

    Also, how long can you spin the motor before the stall fault appears? And does the initial fault occur around the same point every time? Does lowering the motor speed/ duty cycle affect this fault occurrence?

    Best Regards,

    -Joshua

  • 0 in reply to Joshua Maize
    Prodigy 10 points

    Hi Joshua,

    Thank you for your message.

    I have tried increasing the stall detection timing parameter and decreasing both the acceleration and motor speed, but the stall fault still persists. The motor isn't spinning - it only makes a cracking sound, indicating it's just initializing before the stall fault appears. Additionally, the fault occurs at the same point every time, even with a lower motor speed or duty cycle.

    Could you help me figure out a solution for this issue?

    Regards,

    Ramya R

  • 0 in reply to Ramya R
    TI__Genius 12231 points

    Hi Ramya, 

    Thank you for the clarification and details.  

    While I continue to look into this matter, does this fault occurs when there is no load on the motor andthemotor directionis CW (not reverse)? 

    Can you also help to double-check the motor parameters, such as the pole pairs given from the motor data sheet?

    Lastly,  can you try setting the voltage derating setting to 50% instead of 90%?  

    Best Regards, 

    -Joshua

  • 0 in reply to Joshua Maize
    Prodigy 10 points

    Hi Joshua,

    Thank you for your message. 

    Regarding the motor behaviour, I noticed that the motor only starts spinning when the speed is set above 30, and not at the initial stage.

    It spins smoothly without throwing a fault at first, but after sometime, the motor stops and then resumes spinning again.

    However, the motor performance is noticeably smoother compared to before.

    I have attached the pdf with current parameter setting for your reference.

    Regards,

    Ramya

    2744.Drv8350.pdf

  • 0 in reply to Ramya R
    TI__Genius 12231 points

    Hi Ramya, 

    Glad to see the performance increase.  

    Can you set the stall detection threshold to 5 revs, and also can you measure the motor phase voltages and current when this fault occurs? It may be that an overcurrent event/voltage dip on supply is happening shortly when the motor is trying to spin. 

    Best Regards,

    -Joshua

  • 0 in reply to Joshua Maize
    Prodigy 10 points

    Hi Joshua,

    I have set the stall detection threshold to 5 revs but the fault still occurs. I have also measured the motor phase voltage and current values.

    Please find the attached data for your review. 

    Regards,

    Ramya 

  • 0 in reply to Ramya R
    TI__Genius 12231 points

    Hi Ramya, 

    Thank you for the data. 

    That current (peak to peak) is very high, reaching nearly 60A (~ ±31A). The DRV8350EVM is only rated for 15A continuous current and 20A peak current, and so this is most likely resulting in the issues observed with overcurrent fault.  What is the rated current for the motor? And do you have a different motor available to test? Reducing this output current to below the rated threshold should help operation.

    Best Regards,

    -Joshua