Dynamic Modeling and Control for SPMSMs With Internal Turn Short Fault

A dynamic model for a faulted surface-mount permanent magnet synchronous motor (SPMSM) is derived using a deformed flux model. In reflecting the internal turn short into the dynamics, the variations in inductance and back EMF term were considered. Then, the faulted model was transformed into the two synchronous dq-models: one for the positive sequence and the other for the negative sequence. Also, a torque equation, which shows the relation between the ripple and the negative sequence current, is derived. The negative sequence current should be suppressed to eliminate the torque ripple. The dual current controller is utilized for this purpose: in the dual controller, the positive and negative sequences are controlled separately in their own synchronous frames. Notch filters are utilized in each synchronous frame to extract positive or negative sequence component. Experiments were performed with an SPMSM specially designed to make an internal turn short artificially. The experimental results coincide well with the corresponding simulation results, and exhibit a strength of the dual current controller in suppressing the negative sequence current.