A Semi-Analytical Approach for the Optimization of High-Speed PMSM With Halbach Magnet Array

Halbach magnet array is one of the most popular magnet pole configurations for high-speed permanent magnet synchronous machines (HSPMSMs) applications due to the reduced flux harmonics. However, the design and optimization of Halbach array configurations are usually time-consuming since both the magnetization direction and span angle of each magnet segment can be adjusted. To improve the optimization efficiency of this type of machine, this article proposed an intuitive ultrafast semi-analytical optimization method with high accuracy to replace conventional time-stepping finite element (FE) analysis. Magnetostatic FE simulations are used to extract the lookup table (LUT) of the magnetic flux harmonics. The superposition property and the phase shifting property of the magnetic field of the Halbach magnet are verified. A 6s4p HSPMSM motor with the three-segment Halbach array rotor is used as an example to illustrate the advantage and effectiveness of the proposed semi-analytical method. Analytical expressions for the approximation of the Halbach magnet field are derived and the harmonic LUT-based multiobjective optimization is performed. The validity of the optimized cases is examined by both FE analysis (FEA) and experimental tests.