Multi-Physics and Multi-Objective Optimization of a High Speed PMSM for High Performance Applications

High-speed permanent magnet synchronous machine (PMSM) can provide high power density and high efficiency, which is often highly desirable in high performance applications. A multi-physics optimization program based on the multi-objective genetic algorithm was developed in this paper, to achieve a tradeoff solution between the electromagnetic, mechanical, and thermal aspects. First, the parametric electromagnetic model was modeled based on the finite-element method, and then a thermal network model and an analytical mechanical model to determine the thickness of the magnet and the sleeve were developed and merged within a design cycle of the machine, in an effort to attain the target performances of 20 kW/kg at 20 000 r/min for a 2 MW PMSM. Optimization results indicated that a final design with eight poles and 48 slots could obtain a comprehensive performance between power density and efficiency, and the performance satisfied all the requirements.

I. Introduction

High-speed electrical machine has been developed and used for many years, and it is now considered a mature and reliable technology for a number of engineering applications, particularly for direct-drive solutions [1]. With the availability of high-specification materials, development of power electronic converters, and improvement in the manufacturing methodologies, there is currently an unprecedented effort toward developing electrical machines with very high power density and efficiency. This paper targets a power density of 20 kW/kg for a 2 MW drive running at 20 kr/min, and the efficiency requirements need to be >98%. This requirement can meet a number of future potential requirements including marine and other transport system [2].