Winding Changeover System with Multi-Phase IPMSM for High-Torque Density and Wide Operating Region

The application of multi-phase technique is one of the effective options for electric motors that require high power density and wide operating speed range (OSR). However, interior permanent magnet synchronous motors (IPMSMs) with hairpin windings and oil cooling systems suffer from power degradation in the high-speed region due to their high charge rate and current density. In this paper, a winding changeover system (WCS) of a dual three-phase IPMSM is proposed for wide OSR with high power density by shifting the number of phases from six to three. Using the finite element method (FEM), we analyze the effect of phase on torque and power characteristics according to speed and calculate the efficiency of the WCS. Finally, the changeover points for the two operating modes are determined for the system with better efficiency and torque density.