Geometry optimization of a bearingless flux-switching slice motor

This paper presents a geometry optimization for a bearingless flux-switching slice drive. Bearingless slice drives consist of a magnetically suspended rotor disk and a stator with torque and force generation in one single unit. Active bearing forces are often generated in the same plane as the motor torque, while passive axial stabilization is achieved by reluctance forces due to the permanent magnetic bias flux in the air gap. For this operational principle, specific factors have to be taken into account while designing the drive. In addition to motor torque performance, these factors include passive axial force, tilting torque, active bearing force, saturation and liftoff capability. The first optimization cycle analyzes the influence of rotor diameter, motor height and air gap with the goal of maximizing the torque, while maintaining the bearingless operation capabilities. The second optimization cycle deals with the stator teeth geometry. Higher harmonics, saturation and overall performance are analyzed for different teeth width and PM width within the stator.