PMSM Simscape Block - Inertia mask parameter

Hi all! :)

I have a doubt about a mask parameter to be set in the following Simscape block (https://it.mathworks.com/help/physmod/sps/powersys/ref/permanentmagnetsynchronousmachine.html). The parameter to be set is the Combined machine and load inertia coefficient J (kg.m2) and I was wondering if it should be set considering the size as motor side or load side? It is not specified anywhere.

In particular, the rotor has its own inertia J_rotor and also an Harmonic Drive (transmission ratio k> 1) is attached to the motor, which has its own inertia J_HarmonicDrive (defined at the harmonic drive input side). I was wondering how the J mask parameter should be set. Should I pass J = J_rotor + J_HarmonicDrive (i.e. sum of motor side inertias) or J = (J_rotor + J_HarmonicDrive) / k ^ 2 (i.e. sum of load side inertias)?

Thanks!

Answer 1

[Dakai Hu]

Hi Giovanni,

In this case, if you can figure out what J_HarmonicDrive is, I'd use J = J_rotor + J_HarmonicDrive as the inertia parameter for the PMSM block.

[Giovanni Pizzolante]

Thank you very much @Dakai Hu.

I also was asking to myself what is the flux linkage that the model expects. Which unit of measure. Because the flux lin kage can be evaluated starting from the kt (torque constant) and this can be expressed in Nm/Arms and Nm/Apeak.

[Dakai Hu]

Torque constant and permanent magnet flux linkage are always evaluated by peak values, whether its phase-to-neutral current or or phase-to-neutral voltage. So to answer your question it should be (N.m / A_peak).

[Giovanni Pizzolante]

@Dakai Hu thank you very much.