Improved Zero-Sequence Current Hysteresis Control With Reduced Switching Losses for Open-End Winding PMSM Drives With Common DC Bus

In this paper, a novel hybrid space vector modulation (SVM) modulation strategy is proposed to address the shortcomings of the existing zero-sequence current hysteresis control for open-end winding permanent magnet synchronous motor (OEW-PMSM), which can reduce the switching losses without decreasing the modulation range. The common DC bus type OEW-PMSM has gained widespread attention due to its advantages of high dc-link voltage utilization and large output capacity. However, this structure provides a zero-sequence current loop, which leads to hazards such as increased system operating losses and motor torque pulsations. Therefore, suppression of zero-sequence current needs to be considered. In this paper, a novel modulation strategy is proposed for two judgement modes, 6-sector and 12-sector. For different zero-sequence current and voltage vector positions, inverter alternating clamp and normal dual vector modulation are used in the corresponding modes respectively. This strategy can effectively reduce the switching frequency compared to the existing hysteresis control, and its voltage utilization is the same as using the middle hexagon space vector modulation. Finally, it is verified by MATLAB/Simulink simulation that the proposed method can effectively suppress the zero-sequence current and reduce the switching losses.