Mechanism and Suppression of Electromagnetic Coupling for a Flux-Switching PM Machine - Magnetic Bearing Integrated System

To enhance the power density and rotor-dynamic performance of the high-speed magnetic suspension system, a novel integrated topology combining the flux-switching permanent magnet (FSPM) machine with the magnetic bearing (MB) is proposed. Although this integrated design of FSPM machine and MB shortens the axial distance between the machine and the MB, significantly improving system compactness, it also introduces electromagnetic coupling due to the permanent magnets (PMs) located in the stator. Hence, in this paper, the mechanism of electromagnetic coupling arising from the structural integration is investigated firstly, where an integrated equivalent magnetic circuit (EMC) model of the FSPM machine-MB coupling region is established. Based on this EMC model, the coupling effects of the PMs, machine operation, and armature field on the MB are systematically evaluated. Then, the method for suppressing the coupling effect is proposed by optimizing the materials and dimensions in the coupling region. Finally, both predicted and experimental results demonstrate that the suspension force fluctuation of this MB is reduced by 98% and the fluctuation amplitude of the suspension current is about 0.02A, verifying the effectiveness of the suppression method.