A novel rotor design of interior permanent magnet synchronous motors to cope with both maximum torque and core loss reduction

A novel rotor design of interior permanent magnet synchronous motors (IPMSMs) has been developed in order to cope with both maximum torque and core loss reduction for wide speed range applications. First, the flux barrier and permanent magnet shapes of an IPMSM are determined by using an automatic optimization method. In this optimization, the core loss of the IPMSM under flux weakening control at high speeds is minimized under the constrained condition of maximum torque at low speeds. As a result, a novel rotor, which has inner magnetic pole bodies, is obtained. The effectiveness of this design is discussed from both results of the finite element analysis (FEA) and the measurement of a prototype motor. It is revealed that the core loss of the proposed IPMSM at high speeds is significantly reduced, whereas the maximum torque decreases by only a few percent.