A Novel ZSC Regulator with Third-Harmonic Back-EMF Estimation for OW-PMSM Fed by Dual Inverter with a Common DC-Bus

This study proposes a novel method for suppressing zero-sequence current (ZSC) in open-ended winding (OW) PMSM fed by a dual inverter with a common DC bus. The OW-PMSM drive system has gained attention for its higher voltage utilization and potential fault-tolerant capabilities. However, the dual inverter system inherently suffers from the ZSC flows due to the opened neutral point of the stator windings and the common DC bus. ZSC leads to negative effects such as power loss and torque ripple. This work proposes a novel ZSC regulator with the third harmonic back-EMF estimation. The PI-type observer, designed in the synchronous reference frame, is proposed to estimate the third harmonic back-EMF. The proposed ZSC regulator can effectively suppress the ZSC across all speed regions and transient conditions. Simulation and experimental results validate the performance of the proposed ZSC regulator.