Suspension Force-Coupling Analysis of Flux-Reversal Bearingless Slice Motor Based on Advanced Magnetic Field Model

Flux-reversal bearingless slice motor with direct suspension current (DC-FRBLM) is a novel slice bearingless motor. The robust rotor structure of the DC-FRBLM brings benefits including high compactness and ease of manufacturing. However, the disparate frequencies of torque current and suspension currents cause undesirable suspension force-coupling in different radial directions. This feature leads to rotor vibrations and poses challenges for suspension control. To addresses these issues, an advanced magnetic field model and a suspension decoupling control strategy based on this model are proposed in this paper. The proposed model incorporates a precise double-salient permeance model, accounting for variations in rotor magnetic potential and leakage flux. The accurate calculation of the active radial force is achieved using the Maxwell stress tensor method, which agrees well with the finite element analysis (FEA) results. Then an analysis is conducted to identify the magnetic field components responsible for suspension force-coupling. Furthermore, the decoupling strategy based on the proposed analytical model effectively reduces force fluctuation and mitigates rotor vibrations. Experimental results on a prototype of DC-FRBLM validate the improved levitation performance achieved by the proposed decoupling strategy.