Asymmetric Operation of Segmented Dual Three-Phase Electric Machines for Improved Cycle Efficiency

This paper presents an approach to improve the overall efficiency of permanent magnet synchronous machines (PMSM) in driving cycles without decreasing the power and torque density. The conflict between high torque densities and high efficiency in driving cycles results in the prioritization of one of these goals. To address this conflict, a design of a segmented dual three-phase electric machine (DTEM) is presented. The two three-phase winding systems of the divided segments are fed by independent converters and separately optimized for different operating ranges. The resulting DTEM is characterized by an asymmetric geometry and operation. The magnetic coupling between the systems is investigated. The geometry is optimized with coupled numerical simulation. The overall losses in a driving cycle can be reduced up to 3.6% with minor deterioration in torque.