Rotor demagnetization effects on permanent magnet synchronous machines

The effects of asymmetrical magnet faults on the rotor of Permanent Magnet Synchronous Machines (PMSM) are analyzed in the present work. Two different stator winding configurations, series and parallel connected windings, are considered in the analysis. From PMSM with parallel windings, a fault detection strategy based on the information contained in the branch-current spectrum is proposed. A fault severity factor is defined to quantify demagnetization on a single magnet. This factor is practically independent from the motor load conditions. Simulation results using a finite element model are obtained to evaluate the feasibility of the proposal. Additionally, voltage reduction and current derating due to rotor demagnetization are also evaluated. Experimental results are presented to validate the proposal.