PMSM motor controller model, rotor angle output conversion for Park transform

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Hi,

I am developing a PMSM motor controller model in Simulink, I have the PMSM motor from Simpower systems, it gives the motor rotor angle in radians but when I convert it to electrical angle by multiplying by 3 for the number of pole pairs and give it to Clark and park transforms model, the results are not consistent. It gives a linear ramp, I am not sure how to interpret that, I want the conversion so that the park transform and inverse Park transform will work correctly.

Regards,

CB

Answer 1

[CB]

Yes I think the a-phase aligned and d-q axis aligned was the issue. How do we know which one to select? can you please elaborate the difference between two alignments?

[Sabin]

This alignment is a convention used in the model about how the angle theta is defined. This will have a big impact in the Park transform. For an overview about different axis definitions please check the FEM-Parameterized PMSM doc page. There you can see how different definitions will chnage the Park transform. Please note that in other library blocks we assume that Q leads D, the FEM-Parameterized PMSM includes also the case when D leads Q.

Answer 2

[Sabin]

Rotor angle can be seen as a linear ramp when rotor speed is constant. When using it in Park transform the result should be the same as when we reset the angle every 2*pi radians because we need the sin/cos(theta). I suspect the initial angle might be the root cause of mismatch or different axis definition (a-phase aligned with the d or q axis).