Mechanism model of suspension force for spherical bearingless flywheel machine

The flywheel energy storage system (FESS) has drawn more and more attentions in the past decades, and its operation performance is greatly dependent on the suspension characteristics of the flywheel machines. This paper proposed a new mechanism model of the suspension force for the spherical bearingless flywheel machine (S-BFM), which may be applied for the machine optimal design, performance analysis or efficiency evaluation. In the proposed model. the magnetic field partition method was used to solve the permeability of the machine in different diffused flux regions. The inherent characteristics of the rotor eccentricity and magnetic circuit saturation are considered by combining maxwell tensor method and equivalent magnetic circuit method. By considering the rotor eccentricity, magnetic circuit saturation and diffusion flux, the proposed model processes higher precision over the traditional model, and its outputs are quite close to that of the finite element analysis (FEA).