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Lab5 with induction motor

Seok Joo Jang
Prodigy 230 points

I have two questions in lab5. I am using the HVKIT with 28069M CPU.

1. Current controller Kp gain equation at page 81 in InstaSPIN Projects and Labs User's Guide (Version 1.0.10) is different from the software code at calcPIgains function in proj_lab05a.c. Which one is correct?

2. During running an induction motor with lab5b code, the motor does not stop when SpeedRef_krpm = 0. Also when changing SpeedRef_krpm from 0 (motor turning in + direction) to -0.1, the motor overshoots much more than when changing 0.1 to -0.1. Same thing happens for the other direction change. Are these all normal behavior?

Thank you.

  • 0
    TI__Guru** 119520 points

    1. The code. I'll file a bug on the UG.

    2.

    Seok Joo Jang said:
    the motor does not stop when SpeedRef_krpm = 0. Are these all normal behavior?

    This can be common with NO load....Disable ForceAngle helps and look at your speed loop tuning...but there is a slip factor with the induction motor.

    Seok Joo Jang said:
    when changing SpeedRef_krpm from 0 (motor turning in + direction) to -0.1, the motor overshoots much more than when changing 0.1 to -0.1. Same thing happens for the other direction change. Are these all normal behavior?

    You're saying the speed response is worse when starting from 0 vs. starting from + or negative 100 RPM?  Yes, that would be very expected. At 100 RPM the FAST estimator has very good estimates, so it can traverse through 0 speed to the + or - speed quite well.  FROM 0 speed FAST has poor feedback and you might even be using ForceAnble enabled start.  Both cases requires FAST to eventually lock on (in < 1 Hz) and then drive the control system appropriately.  It will certainly have more overshoot.

    Highly recommend evaluating InstaSPIN-MOTION and the SpinTAC controller for low speed ACI performance. Very good.

     

  • 0 in reply to ChrisClearman
    Prodigy 230 points

    I'm glad to hear that what I saw was the expected result. Will go to the following labs and hope to see the better performance with SpinTAC controller.

    Thank you.