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motor rotating direction problem for instaspin

Fei Yan1
Intellectual 575 points
Other Parts Discussed in Thread: MOTORWARE

Hello, Chris,

I am using  DRV8312-69M-KIT to test a sensorless system. My encoder is Magnetic Quadrature encoder AS5047D. 

Motorware version is 13 and CCS version is 5.5.0.

Now I can run the project 12b and 12c. But there are some problems.

For the project 12b, I can not set a negative speed. If a negative speed the motor will stop. It will rotate normally when a positive speed.

For the project 12c, if rotating the motor clockwise, the system will not make the motor go back to the postion 0.  if rotating the motor anti clockwise, the position control function works. I think the problem is that the motor can not rotate anti clockwise.

Then I go bakc the project 2a, 2b and others. In project 2a, the speed can be set to a negative value and it will rotate anticlockwise. but in project 2b and others, the motor can not rotate anti clockwise.

How can I check my problem?

Thank you

Fei

  • 0
    TI__Guru** 118000 points

    first check your compiler. the "can't run in reverse" is a common symptom

    http://e2e.ti.com/support/microcontrollers/c2000/f/902/t/295599.aspx

  • 0 in reply to ChrisClearman
    Intellectual 575 points

    Hello, Chris,

    Thank you for your answer. I have solved the above problem.

    I am testing project 12b with a low RPM speed(<10 RPM). The motor can not spin very smoothly. How can I improve this perormence under a low speed?

    Motor parameters:

    Pole Pairs: 7

    ABI encoder lines: 500

    Thank you

    Fei

  • 0 in reply to Fei Yan1
    Guru 12800 points

    Fei,

    Assuming that you are running the speed loop at 1kHz, the minimum resolution of that encoder is 30rpm.  

    It is very difficult to control the speed at 10rpm with that level of quantization error.  

    There are a couple of ways to help with this situation.  

    1. Increase the filter for SpinTAC Position Converter.  You do this by increasing the value provided to this function STPOSCONV_setLowPassFilterTime_tick in spintac_velocity.h file.  This will more heavily filter the velocity signal before it is provided to SpinTAC Velocity Control.  The downside of this is that it will cause a small lag in the velocity feedback which can impact dynamic performance.

    2. Modify the eQEP hardware to make use of the periodic timer.  This will allow the encoder module to more accurately measure the speed that the motor is running at.  Right now we don't have an example of how to do this.  But we are planning on adding one in the future.