Optimization of permanent magnet motor air-gap flux density based on the non-uniform air gap

In order to reduce the negative effects of permanent magnet motor performance caused by excessive harmonic content in air-gap magnetic field, the optimal design of permanent magnet motor based on the Taguchi method and time-stepping FEM with built-in “V” type rotor magnetic circuit structure was proposed in this paper. Firstly, taking four structural parameters of permanent magnet motor as optimization variables and two characteristics of motor as constraint, the multi-objective multivariate optimization of the permanent magnet rotor with the structure of non-uniform air gap was carried out and the optimum rotor structure with the appropriate no-load air gap flux density waveform is obtained. Then the advantage and the accuracy of the optimized results with Taguchi method were verified by comparing the air gap flux density harmonic content before and after the optimization. Finally, the electromotive force waveform considering the stator skewed slots was calculated with time-stepping FEM to verify the effectiveness of the air-gap flux density optimization further.