Multiharmonic Torque Ripple Optimization in Phase Current Reconstructed OW-PMSM Drive With Single-Phase Open-Circuit Fault

When encountering the single-phase open-circuit fault, the open-winding permanent magnet synchronous motor (OW-PMSM) drive can automatically switch to the two-phase operation due to the inherent fault-tolerant ability. However, the inevitable zero-sequence current (ZSC) of fundamental frequency interacts with the third-order back electromotive force (EMF), resulting in severe torque ripple. Accordingly, the system performance and the output quality are therefore degraded. In addition, after the current in the faulty phase rapidly decays to 0, the corresponding two power legs lose their regulating ability to the current. This makes the phase current reconstruction strategy for normal operation unavailable in the post-fault operation. In this article, a novel torque ripple suppression scheme is put forward for the OW-PMSM drive with open-phase fault. The proposed method coordinates multiple high-order torque harmonics by injecting the harmonic current of only a single frequency, which establishes two methods for torque ripple optimization. Moreover, the phase current reconstruction scheme is modified to make it compatible not only with the post-fault operation but also with the torque ripple optimization strategy. Finally, experimental verification is carried out on an OW-PMSM drive to prove the feasibility and effectiveness of the proposed strategy.