Topology and Voltage-Balancing Control of Novel Asymmetrical Six-Phase OEW-PMSM Drives Toward Higher DC-Link Voltage Applications

This paper introduces a three-stage series-connected dc-link inverter for asymmetrical six-phase open-end winding PMSM(ASP-OEW-PMSM), addressing voltage limits in SiC and GaN devices and reducing partial discharge risks in higher dc-link voltage systems, which could be applied in medium-voltage direct current (MVDC) systems. A voltage control algorithm is proposed to ensure capacitor voltage balancing despite phase parameter inconsistencies. Experimental results are presented to validate the proposed topology and its voltage control method. By reducing number of switches and simplifying the system compared to multi-level solutions, the approach triples bus voltage compared to two-level inverters, leveraging the six-phase motor's degrees of freedom(DOF).