I have built a half bridge rectifier for a 3 phase PMSM. i am using hybrid switches in it and have set the appropriate turn on/off delay times for the hybrid switches. additionally i have also set a delay time so that the top and bottom row of switches in the rectifier are not activated at the same time and creating a short. at speeds up to 1000rpm i can see the 3 phase currents behaving as expected and am getting appropriate loss values for the switches. as i start to go above 1000rpm (with everything else fixed), the current waveforms get imbalanced and so does the speed and i get very high switch losses (in the range of 1e6). i have attached my model, is there a setup issue or am i missing something obvious?
You are re-using the controller design from a PLECS demo model. One difference in that example is that the machine has Ld=Lq and Ld is used in the plant model for controller tuning. In your model Ld = Lq / 3. If you set Ld=Lq then the oscillation goes away. You must adjust the controls design to better handle saliency, for example only Ld is used in the controller design and the feedforward term is only Ld and not Ld and Lq.
I removed the thermals in the attached model. It is working at 1.5 kRPM. You can use the PLECS Compare feature to differentiate the models. Oliver’s comment about the machine speed is critical.
I ran the model you had attached, ait seems to manage until 7000rpm and then it falls apart again as soon as i put to 8000 rpm.
not disrespecting the changes you’ve made themselves, just trying to understand what is causing this?
