PWM Strategy in OVM and Six-Step Regions for Open-End Winding PMSM Fed by a Dual Inverter With a Common DC Bus

This study proposes a novel pulsewidth modulation (PWM) strategy in high modulation index (MI) regions for the open-end winding permanent magnet synchronous motor fed by the dual inverter with the common dc bus. The dual-inverter system is getting attention due to the higher voltage utilization and the potential fault-tolerant capability. However, the dual-inverter system inherently suffers from the zero-sequence current (ZSC) flowing due to the opened neutral point of the stator windings and the common dc bus. This ZSC causes negative effects, such as power loss and torque ripple. Various PWM schemes have been proposed to suppress the ZSC. However, the conventional methods focus on a linear MI region and have performance degradation due to the limited voltage modulation margin. This study proposes simple PWM schemes for the ZSC control in the overmodulation and six-step regions. The proposed method can suppress the ZSC while maximizing the voltage utilization with minimum switching loss increase. Simulation and experimental results are provided to verify the performance of the proposed PWM strategy.