Usage of field oriented control PMSM block

Hi,

I am trying to model a torque controlled PM synchronous motor in simulink, using the following FOC PMSM block in torque mode: https://www.mathworks.com/help/physmod/sps/ref/pmsmfieldorientedcontrol.html

I'm sending it a constant torque command of 300Nm, but it's producing oscillating torque.

Please let me know what I'm doing wrong. Thanks

Answer 1

[Joel Van Sickel]

Hello Yuhui,

I would first start with the step size of your model. You will often need a step size of 1us or smaller for fixed step if doing motor control. I don't know your switching frequency, but typically a 10khz frequency would warrant 1 us step size. It should ajust linearly with switching frequency, aka, 20khz is a 0.5 us step size, etc. However, your model isn't completely diverging, so that might not be the issue. This controller does require that you tune the loops for it to work, so it is also possible that you need to spend more time working with the control loops to get them to work. Also, as this control block was designed for the simscape motor, and not the specialized power system motor, it would be easy for the parameters, or the speed/position to be slightly different than what the controller is actually expecting. I would compare the calculated id and iq of the controller with the id/iq of the motor and make sure that they match up. If they do, you know your parameters are correct.

Regards,

Joel