Effects of partial rotor demagnetization on permanent magnet synchronous machines

The effects of magnet faults on the rotor of permanent magnet synchronous machines are analyzed in the present work. In particular, demagnetization effects are analyzed using the finite element method. Two different stator winding configurations are considered in the analysis, series and parallel connected windings. From this analysis, a fault detection strategy based on the information contained in winding-current spectrum is proposed. A fault severity factor is also proposed to quantify residual magnetism losses (demagnetization) on a single magnet. This factor is practically independent from the motor load conditions. Experimental results are presented to validate the proposal.