Multiphysics Analysis of Flywheel Energy Storage System Based on Cup Winding Permanent Magnet Synchronous Machine

In order to solve a series of problems such as electromagnetic loss, mechanical strength, rotor dynamics, and vacuum cooling induced by the high-power machine in flywheel energy storage system (FESS), a multiphysics coupling field of electricity, magnetism, stress, thermal and fluid is adopted to conduct a comprehensive analysis of a high-capacity FESS. Firstly, a structure of high-power cup winding permanent magnet synchronous machine (PMSM) for wind power frequency regulation is proposed in this article of which the electromagnetic characteristics are analyzed by the finite element method (FEM). Secondly, the temperature of the flywheel under vacuum environment is analyzed by establishing a fluid-solid coupling thermal model. After that, the mechanical strength of the machine is researched based on the theory of elasticity and thermal coupling, and the rotor dynamics is studied by modal analysis. Finally, an overall prototype of the FESS is fabricated and the performance of electromagnetic, stress and temperature are validated. The experimental results verify the relevant theories and simulation analysis, which can finally realize the reliable operation of the high-capacity FESS.