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Questions about using 28069M with FAST on ACIM

user4187057
Intellectual 420 points

Other Parts Discussed in Thread: MOTORWARE

hello,

      I use the high-voltage kits to run my ACIM. The dsp is 28069M, using the sensorless method of FAST module. But in the experiments, when i change the idref, i found the estimated speed from FAST is not accurate. Like the follow picture, the real speed is obtained from the encoder. At the time of changing idref, the two speeds have different values. 

     So how to solve this problem? thanks very much.

  • 0
    TI__Guru** 117140 points
    Id is the magnetizing current of ACIM, is often equal to Id_rated in instaSPIN. The motor speed will vibrate if you change it fast without any ramp control, and is not more lower or higher than Id_rated except the motor need field weakening control for high speed.
  • 0 in reply to Yanming Luo
    Intellectual 420 points
    But when i add the ramp control of id_ref changing, the two speeds are also different so much.
    I want to know how to calculate the estimated speed , are there some papers for me?
    I think the estimated method is not very accurate in the big dynamic state.
    Now i use my method to run the motor at the optimal state of efficiency, so i need to change the id_ref.
    But the estimated speed is not same with my real speed which is from encoder, almost a big difference. So it makes some wrong state in the control, just like the real iq_ref should be positive when i change the idref which leads the real speed drops and small than reference, but in the experiment it become negative because the estimated speed is higher than reference. So I want to get some ways to make the estimated speed more accurate. THanks.
  • 0 in reply to user4187057
    TI__Guru** 119680 points
    are you sure your motor parameters are correct in the first place?
  • 0 in reply to ChrisClearman
    Intellectual 420 points

    Now I have two ways to get the parameters of the ACIM. One is using the test dates from the motor manufacturer to calculate the parameters; the other way is using the lab of motorware to identify the parameters.The results of the two ways  are also different so much.

    Besides, do the same identify lab of motorware at different time, I also get different results. So in my final project, i use the parameters of my calculation to do the experiments. 

  • 0 in reply to user4187057
    TI__Guru** 117140 points
    What parameters are different with your calculate?
    1. To identify the ACI motor parameters, need to lock the rotor for identifying Ls and Rr.
    2. Increase USER_MOTOR_RES_EST_CURRENT and USER_MOTOR_IND_EST_CURRENT to identify R and L based on motor rated current.