A Novel Variable-Flux PMSM with Parallel Hybrid Magnets Capable of Operating in a Wide Speed Range

Variable-flux permanent-magnet synchronous machines (VF-PMSMs) have been widely researched for their ability to expand the speed range and reduce loss by manipulating magnetization state (MS) dynamically. The hybrid PM configuration using variable PM (VPM) with low coercive force and constant PM (CPM) with high coercive force, is widely used in VF-PMSMs to improve the torque density. A novel VF-PMSM with parallel hybrid magnets is proposed in this paper. The topology, operating principle and pole/slot combinations of the proposed machine are analyzed. And the electromagnetic performances, including air-gap flux density, back-EMF and torque capability, are evaluated through finite element analysis (FEA). The efficiency improvement of the proposed machine is evaluated. The results prove that the proposed machine is capable of operating in a wide speed range with high performance.