Multiple-phase permanent magnet synchronous machine supplied by VSIs, working under fault conditions

In a high power embarked system, the use of permanent magnet synchronous Machines (PMSM) is justified when high torque-volume ratio is required. In this paper, the authors study a multiple-phase PMSM where each phase is separately supplied by its own H-bridge voltage source inverter (VSI). This segmented structure allows to impose the defined current waveform correctly in order to minimize torque ripple. For a q-phase nonsinusoidal nonsalient PMSM, an optimal current waveform, minimizing the copper losses with a constant torque, is defined under normal operating mode. In a degraded operating mode, corresponding to the suppression of the supply of one or more than one phases, a simple and efficient method to cancel torque undulations, generated by faulty phases, is presented, For each faulty phase, torque ripples are filtered by the modification of one faultless phase current waveform.