Topology Choice and Optimization of a Bearingless Flux-Switching Motor with a Combined Winding Set

Vedran Jurdana,Wolfgang Gruber,Neven Bulic

doi:10.3390/machines6040057

Vedran Jurdana, Wolfgang Gruber + Show 1 more

Open Access

https://doi.org/10.3390/machines6040057

Copy DOI

Abstract

The purpose of this paper is to choose a new topology for bearingless flux-switching slice motors, regarding the number of stator and rotor poles, with a combined winding set. Additionally, the selected motor topology is optimized with finite element method (FEM) simulations to improve the performance. Bearingless slice drives feature a magnetically-suspended rotor disk passively stabilized by reluctance forces due to a permanent magnet (PM) bias flux in the air gap and actively controlled by the generation of radial bearing forces and motor torque. Usage of the combined winding set, where each phase generates both motor torque and suspension forces, opens the opportunity for a new topology. The topology choice and optimization are based on FEM simulations of several motor optimization criteria, as the passive axial, tilting and radial stiffness values and the active torque and bearing forces, which are simulated regarding the motor height and specific stator and rotor parameters. Saturation, cogging torque and cogging forces are also analyzed. The 3D FEM program ANSYS Maxwell 2015 was used. The results led to an optimized bearingless flux-switching motor topology with six new stator segments and seven rotor poles. By optimizing the geometry, a considerable improvement of performance was reached. This geometry optimization is a base for a future prototype model.

Highlights

The results led to an optimized bearingless flux-switching motor topology with six new stator segments and seven rotor poles
The cogging torque represents the torque exerted on the rotor only by the permanent magnet (PM) field (Tz,cogg (0 At) in Table 3), which leads to torque ripples and should, be small and exceeded by the active motor torque with 1000 At in one coil (Tz,i (1000 At) in Table 3); The cogging forces are the forces exerted on the rotor only by the PM field (Fx,cogg (0 At) and
The geometry is optimized by simulations

Summary

Introduction

History and Description of the Bearingless Motor. At the beginning of the 20th Century, the idea of magnetic levitation was presented, which was followed by the development of concepts to stabilize a rotor [1,2,3,4,5]. This research led to the development of the first bearingless motor. The bearingless motor concept started developing and spreading in universities and industry world-wide around the year 1990, especially in Japan and Switzerland [1,2,3,4,5]. The bearingless motor is a magnetically-levitated drive generating both torque and bearing force in one single device.

Objectives

Results

Conclusion