Efficiency Improvement for Concentrated Flux IPM Motors for Washing Machines

Abstract

Concentrated flux interior permanent magnet (CFIPM) motors have the advantage thattheir utilization of flux linkage is more efficient than that of general IPM motors and CFIPM motorsare suitable for washing machine motors, which demand low-speed, high-torque specifications. However, low efficiency occurs in the low-speed high-torque mode considering the high-speedoperation for spin mode. This paper proposes a magnet overhang structure between the rotor core thatreduces leakage flux and improves efficiency for a CFIPM in wash mode. Optimization of the 3Ddesign of magnet overhang structures is performed to improve the efficiency with the same quantity ofpermanent magnets. The validity of the optimal design is experimentally verified through thefabrication of prototypes.