Electromagnetic loss investigation and mitigation in switched flux permanent magnet machines

This paper presents the electromagnetic loss analysis and mitigating methods of switched flux permanent magnet (SFPM) machines. The 2-dimentional finite element (2-D FE) method is used to calculate the flux density in all the mesh elements within stator and rotor iron cores, then the stator and rotor hysteresis, eddy current and excess losses are calculated. The PM eddy current losses have been calculated as well by using 2-D FE method. The methods such as segmenting (either radially or axially) the permanent magnets or modifying the ratio of rotor pole to pole pitch have been employed for eddy current reduction. The FE results have shown that the proposed methods are very effective in reducing PM eddy current losses without sacrificing the average torque of the investigated SFPM machines.