Design and Multi Objective Stratified Optimization of a Less Rare Earth Hybrid Permanent Magnets Motor With High Torque Density and Low Cost
The price fluctuation and the unstable supply chain of rare earth permanent magnet (PM) have posed potential risks for further application of rare earth PM motors. To alleviate the consumption of rare earth PM material, a less rare earth PM brushless motor with two types of PM materials is proposed in this paper. The key of this motor is that the rare earth PM is purposely combined with a non rare earth ferrite PM, forming the hybrid PM excitation. To design the proposed motor efficiently, a multi objective stratified optimization strategy is proposed, where the selected five optimization objectives of output torque, PM cost, cogging torque, torque ripple, and efficiency are divided into two levels. Then, different optimization methods are skillfully combined to meet the specific design requirements. The corresponding electromagnetic performances are analyzed and compared with the baseline rare earth PM brushless motor. Finally, several experiments of the two motors are carried out for evaluation. Both theoretical analysis and experimental results verify the feasibility and validity of the proposed motor and the optimization method.
IEEE Transactions on Energy Conversion