A comparison of IPM traction machines with different PM materials

It is widely recognized that interior permanent magnet (IPM) synchronous machines are suitable for vehicular applications, especially served as traction drives for hybrid and battery electric vehicles. In this paper, IPM machines with rare earth permanent magnets (REPM) and machines with ceramic ferrite permanent magnets (CFPM) specially designed with stronger flux-concentration rotor structure are analyzed, constructed and evaluated. The performance studies of those prototypes are presented by using the finite element analysis method. The torque capability, efficiency, overload situations, field-weakening characteristics and operating ranges are investigated. The experimental results match the theoretical analysis. The comparison shows that the IPM machines with ceramic ferrite permanent magnets can be considered as a lower cost alternative for vehicular applications with comparable performance.