Magnet Eddy Current Loss and Thermal Analysis of a Dual-Permanent-Magnet-Excited Machines

This article investigates the eddy current loss mechanism of a dual-permanent-magnet-excited machines (DPMM). Based on the flux modulation effect, abundant harmonics are induced in the air gap of DPMM. The harmonics of air-gap flux density due to rotor permanent magnets (PMs), stator PMs, and armature reaction are investigated qualitatively and separately. Then, the orders, frequency, and rotation speed of the harmonics are deduced theoretically. The harmonics that contribute to the eddy current losses are deduced accordingly. Finally, the loss distribution of the proposed DPMM is estimated through simulation and the thermal field of the proposed motor is analyzed. A prototype is fabricated to validate the analysis. Temperature rise of both stator and rotor PMs under rated load condition is measured through experiment.