How to Reduce PMSM SH Signal Error In High Impedance Conditions

When the equivalent impedance to the PMSM SH model is very high, small errors in the machine currents (Ia, Ib and Ic) can cause high voltage errors to occur at the input legs of the machine. Since the voltage noise is connected to the machine inputs, a positive feedback loop can occur causing instability or increased errors in the PMSM SH simulation.

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In order to avoid this situation, it is necessary to start the simulation with the machine resistances higher than the values defined by the model file. When the machine is in a lower impedance operating state, return the machine resistances values to the ones defined by the model file. The following procedure describes how to accomplish the procedure using the Resistances Override Channels.

Procedure

1. Enable Enable Advanced Channels on the PMSM SH Page of the desired PMSM SH machine.

2. Set the default value of the Enable Resistance Override channel to True (1).

3. Set the default values of the Resistance Phase A Override, Resistance Phase B Override and Resistance Phase C Override channels to a Resistance value bigger than the one used by the model file. Typical starting values should be between 10 and 100 Ohms.

4. Save the system definition and deploy it with the new changes.

5. After the simulation has started, add the Advanced Channels of the desired PMSM SH to your UI.

6. As soon as the machine is in a lower impedance operating state, you can return the resistance values to the standard operating values by decreasing the values of the Resistance Phase A Override, Resistance Phase B Override and Resistance Phase C Override channels to the values specified in the model file.