Magnetically Levitated Slice Motors

This paper provides a comprehensive overview of different concepts of magnetically levitated slice motors with ring-shaped rotors that differ in their construction and the way the bearing forces and drive torque are created. After a general classification of magnetic bearings and the description of the technical principle of the topologies, the design constraints for a fair topology comparison are specified. Mechanical, magnetic, electrical, and thermal design considerations are discussed and supported by 3-D finite-element method simulations. Four promising motor topologies are compared qualitatively and quantitatively by different criteria, such as acceleration behavior, compactness, bearing stability, and complexity of the control. The comparative evaluation is supported by performance measurements on laboratory prototypes.