• State
  • Locked Locked
  • Replies 5 replies
  • Subscribers 29 subscribers
  • Views 1213 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Motor stop at specific speed/torque

Jan Feiling
Prodigy 50 points
Other Parts Discussed in Thread: DRV8302, DRV8301

I want to control an AC Servo Motor APM-SC05ADK-9 with the Motordriver DRV8302.


For that, I use as basic program the PM Sensorless example and change the code for my usage. The program works and the motor is moving. 

But, if the torque is to high, or even the speed, the motor stop and I have to restart my debug session. I looked into the control and status register, to identify the problem, but I could not find anything.

I appriciated any help and assumptions to identify the error. 


Jan

  • 0
    TI__Mastermind 21305 points

    Hi Jan,

    Are you hitting an overcurrent FAULT as you go to higher currents? It is possible the FAULT is removed if the MCU restarts or the condition is removed.

    Can you monitor the FAULT pin with an O-scope to see if it ever asserts?

    What is the overcurrent setting and what level of current are you trying to drive?

  • 0 in reply to Nicholas Oborny
    Prodigy 50 points

    Hi Nick,


    when I monitore the FAULT pin the value is at zero, even when the motor stops.


    The overcurrent setting is:

    DRV8301_cntrl_reg1.bit.GATE_CURRENT = 0;      // full current 1.7A
    DRV8301_cntrl_reg1.bit.GATE_RESET = 0;            // Normal Mode
    DRV8301_cntrl_reg1.bit.OC_MODE = 0;                  // current limiting when OC detected
    DRV8301_cntrl_reg1.bit.OC_ADJ_SET = 0;            // OC @ Vds=0.060V

    The Rds(on) value of the Moseft is 0.00325 ohm. Is there a possibility to lower the Vds value. Because now the calculated IOC = 18.46 A.

    I want a max current of around 10 A.

    Tank you.

    Jan

  • 0 in reply to Jan Feiling
    TI__Mastermind 21305 points

    Hi Jan,

    FAULT should be high during normal operation.

    Are you using an EVM or your own PCB? Can you give give the Part Number of the EVM if you are using one.

    I would recommend having 25-50% margin in the overcurrent protection as noise from the half-bridges can cause false trips. It is also not advised to set the VDS trip level below 0.125. I believe the accuracy is degraded below this level.

    What is the MOSFET Part Number? What is driving the need for such low Rds(on) MOSFETs with only 10A peak?

  • 0 in reply to Nicholas Oborny
    Prodigy 50 points

    Hi Nic,


    what can be the reason that the fault pin is low the whole time?


    I using the DRV830x-HC-EVM.


    The Mosfet part number is SUM110N06-3m9H (http://www.vishay.com/docs/73236/sum110n0.pdf).


    I use motors with peak current of 21.2 A and a 10.6 A continous currunt. Should be the limit for the current higher?

  • 0 in reply to Jan Feiling
    TI__Mastermind 21305 points

    Hi Jan,

    If you go to page 15 of the DRV8302 datasheet it shows you the different FAULTs and their reporting modes. I think your current limit is appropriate.

    If you are in current limit mode the FAULT should not be latched. Can you double check this by reading the registers?