Why the oscillations never ending in open loop operation of PMSM?


I’m trying to simulate a PMSM motor with open loop operation, please check the attached PSIM file. In the simulations the oscillations in the shaft torque , speed, id and iq currents are sustaining i.e oscillations are not reducing. Whereas my expectation of shaft torque , speed, id and iq currents are as like in the attached figures.

I gave the load torque as a step input using time driven lookup table. Therefore after increasing the load torque, the motor speed and torque should oscillate and come to steady state, but it’s not happening in my simulations, So, what would be the problem? Moreover I also have a doubt regarding Vpk/Krpm and torque flag values. My magnet flux is 0.822 Wb and therefore line to line induced voltage in stator is 0.8221000sqrt(3), so, is it correct?

I’m getting the plots different when I put torque flag value (0 or 1). So which flag value should I use?

Please check all the values in the motor parameter dialog. I doubt this motor rating is sufficient to drive your load. The definitions of those parameters can be found by clicking the “Help” button in the parameter dialog.

The most obvious incorrect value is Vpk/krpm = 1423.7. It seems too large with the input voltage of 200Vrms.
The value of Vpk/krpm should be available from the machine data sheet. If this data is not available, it can be obtained through an experiment by operating the machine as a generator at 1000 rpm and measuring the peak line-to-line voltage.