Multi-Physics Coupled Analysis and Global Optimization of High Power Density Permanent Magnet Machines

High power density machines have attracted increasing attention, but they are reaching the thermal and mechanical limits of the materials, bringing challenges to the machine designs. In this paper, a reliable and effective multi-physics coupling analysis is integrated to the global optimization based on genetic algorithm, to improve the optimization efficiency. The basic modeling on fluid, temperature, electromagnetic, and mechanical fields are introduced, and their couplings as well as the general optimization process are highlighted. Afterwards, a cased study based on the surface-mounted permanent magnet (SPM) machine with the rated power of 15 kW at the speed of 20000 r/min is detailed to describe the optimization process.