Research on Fast Design of Key Variables of Bearingless Flux-Switching Motor Based on Variable Structure Magnetic Network

Abstract

The bearingless flux-switching permanent magnet motor (BFSPMM) adopts the stator permanent magnet structure, which is beneficial to the heat dissipation of the permanent magnet and reduces the risk of demagnetization caused by the temperature rise of the permanent magnet. However, since BFSPMM adopts the double-salient structure, the design method of the traditional rotor permanent magnet type motor with sine wave back electromotive force cannot be directly applied. Thus, the design of the BFSPMM is complicated and time consuming. To this end, this paper proposes a method to quickly design the key parameters of the BFSPMM, such as optimum tooth width ratio, electromagnetic torque, winding coupled permanent magnet flux, suspension force, etc. First, in order to overcome the shortcoming of finite element time consuming, a new variable structure magnetic network model (VSMNM) of the BFSPMM is built considering the eccentricity of rotor. Second, the expressions of the optimal rotor-to-stator tooth width ratio and the coupling permanent magnet flux linkage in power winding are directly deduced based on the proposed VSMNM. Then, the electromagnetic torque is deduced based on the permanent magnet flux linkage, and the suspension force is deduced based on VSMNM. Finally, the fast design method proposed in this paper is verified to be effective by the finite-element analysis and the experimental results.