Analysis of Unbalanced Force for Flywheel Energy Storage System Based on Active Magnetic Bearing Considering Rotor Eccentricity Effects

Flywheel energy storage system(FESS) based on active magnetic bearing(AMB) can be used to generate impulse electric power. The unbalanced forces considering rotor eccentricity need to be calculateded, especially when the discharging current is high. This paper investigates the unbalanced forces in FESS considering rotor eccentricity. The analytic solution for the magnetic flux density distribution in the airgap region is used to calculate the unbalanced Lorentz forces and magnetic forces, which are compared with that of finite element method(FEM). The results show that the unbalanced forces should be calculated for FESS to guarantee the flywheel safe whirling and provide reference to the control system design of AMB.