Neutral Voltage Modeling and Handling Approach for Five-Phase PMSMs Under Two-Phase Insulation Fault-Tolerant Control

Five-phase permanent magnet synchronous motors are demanded in many safe-crucial applications for their appealing fault-tolerant capability. Unlike most previous articles on open-circuit faults and line-to-neutral faults, this article concentrates on two-phase insulation faults, including the two-phase interturn fault (ITF) and the interphase fault (IPF). ITF and IPF represent two common unbalanced conditions’ cases in which the motor's neutral voltage (NV) is rather unstable. This leads to incorrect phase-voltage modulation (PVM) if the NV issue is ill-considered. Thus, this work proposes a general method to handle NV for two-phase insulation faults. In light of this, a comprehensive faulty motor model is established by introducing two synthetic phase-voltage quantities, which correspond to the real phase voltages in the healthy mode. Based on this, a general NV model in postfault is derived, and further presvented is a revised PVM that is independent of the fault severity level. Finally, the experimental results confirm the validity of the presented method for handling NV under various fault conditions.