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Maximum motor speed using Instaspin and Drv8301 kit

Hiroyasu Matsubara
Expert 1405 points

Other Parts Discussed in Thread: DRV8301, INSTASPINUNIVERSALGUI

Hello,

I'm now trying to drive 3 phase low-inductance motor by using Drv8301 kit and Instaspin.

I'm using Instaspin Universal GUI , and using "lab 5b".

Now I wonder,when using 7 pole pairs low inductance motor,the maximum speed rpm which is displayed on the GUI is

10286 rpm , but when drives it by Instaspin lab 5b,the maximum speed is about 5800 rpm,and couldn't drive faster than it.

The motor parameter (Rs and Ls etc.) is identified by using lab 2c.

The motor parameters are : Rs = 0.0191654 Ohm, Ls = 0.0021711 mH,Flux = 0.0179348 V/ Hz.

And,this problem was not occured when using another 3-phase motor , which pole pair is two.

Could someone tell me what the reason of this phenomenon ?

I would appriciate if someone could reply to my question.

Regards,

Hiroyasu

  • 0
    TI__Guru** 119680 points
    in your user.h did you set
    USER_MOTOR_Ls_d (0.0021711)
    or to
    USER_MOTOR_Ls_d (0.0000021711)

    the latter is correct. Although 2uH is VERY, very low.

    what do you mean by: the maximum speed rpm which is displayed on the GUI is 10286 rpm

    which speed? when?

    I suppose this is calculated from an max frequency of 1200 Hz in your user.h
    1200 Hz * 14 poles = 10286 RPM

    that's just a maximum limit that you defined in your user.h. Not what the motor will actually do.

    However, based on the parameters of this motor - if they are correct - I would expect you to be able to run somewhere in that range.

    for the speed control gain with this type of motor make sure you take the default Kp and Ki values and /10. that's a good starting point for these motors.
  • 0 in reply to ChrisClearman
    Expert 1405 points

    Thank you for your reply.

    I wrote the motor inductance value on the user.h by using latter.

     USER_MOTOR_Ls_d (0.0000021711)

    I mean the maximum speed is , displayed in the "Estimated RPM" column on Instaspin Universal GUI.

    The phenomenon may be caused by the limit of the motor specification,I think.

    The datasheet of the motor isn't mentioned about the maximum speed of the motor...

  • 0 in reply to Hiroyasu Matsubara
    TI__Guru** 119680 points
    The "Maximum RPM" value in INSTASPINUNIVERSALGUI is simply
    gUserParams.iqFullScaleFreq_Hz * 60 / gUserParams.motor_numPolePairs

    it is the theoretical limit based on your motor poles and the full scale frequency. As I described above.

    this is not the actual maximum RPM for your motor. that will be determined by the motor design, voltage on the bus, and modulation used.