Design and Optimization of Forced Air-Cooled High-Power-Density Permanent Magnet Machines Based on Multiphysics Hierarchical Strategy

A multiphysics hierarchical optimization strategy is proposed to enhance the optimization efficiency and quality of high-power-density permanent magnet (PM) machines. The analytical models for the thermal and mechanical fields are developed, which contribute to the fast and reliable sensitivity analysis together with the 2-D finite element (FE) method for the electromagnetic field. Moreover, the layered optimization with iterations is conducted based on not only the sensitivity rankings of design variables but also the couplings between the three physics fields, in which the analytical, FE, and computational fluid dynamics (CFD) methods are carefully integrated into three different groups. As a result, high optimization efficiency is ensured, and the globally optimal design for the three physics fields is identified. A case study with the multiobjective optimization is detailed to elaborate on the strategy. Finally, a prototype machine is fabricated and measured for experimental validations.