FOC speed control oscillation

Dear All,

I have simulated a Velocity control based Field Oriented control, controlling the motor (Pre-parameterized Swiss SMXN7-3000) fed by 3-phase converter. As the plant is non-linear, the direct auto-tune was not possible and I have tried the way to tune the PI gains by creating new plant using I/O port, still no success and for that I have tried manual tuning (Try and error). Now, the output speed is somewhat follows the reference speed, but there are oscillations in the output speed even at 0 rad/sec. Moreover, these oscillation increases at higher speed.

I have attached the snapshot of rela vs reference speed, and due to oscillations, the PWM signal and current are so distorted, that they dont even form Sine wave.

What could be the problem with this Model and how can I approach this problem for possible solution.

Answer 1

[Sabin]

This is probably due to controller parameterization. I suggest trying to use the PID autotuner which can deal with non-linear systems. The PID autotuner will require a stable initial controller which seems to be the case here. Check out this example about tuning PMSM controllers using PID autotuner:

https://www.mathworks.com/help/slcontrol/ug/tune-field-oriented-controllers-for-a-pmsm-using-closed-loop-pid-autotuner-block.html