High-Precision Modulation Strategy for Hybrid-Inverters-Based OW-PMSM Drives

This article conducts a research on high-precision modulation of open-winding permanent magnet synchronous motor (OW-PMSM) drives fed by two isolated dc sources with unequal dc-link voltage. To enhance the performance while considering the cost of the drive, the high-voltage-side inverter (INV1) adopts IGBTs as switching devices and the low-voltage-side inverter (INV2) adopts low-cost MOSFETs as switching devices. Based on the developed OW-PMSM drive, high-precision modulation strategies for the voltage ratios of 2:1 and 3:1 are proposed in this article. In the proposed modulation strategies, the vector planes generated by the dual inverters are divided twice and the reference voltage vector is allocated according to the specific subsector. INV1 adopts clamping modulation and INV2 adopts high-frequency modulation, which can fully utilize the high-voltage characteristic of IGBT and the high switching frequency characteristic of MOSFET to fulfill multilevel and high-precision outcome. The proposed drive and modulation strategies are verified through experiments.