Performance Benchmarking of a Novel Magnet-Free Bearingless Synchronous Reluctance Slice Motor

• Published in: IEEE open journal of the Industrial Electronics Society Vol. 1; p. 1
• Main Authors: Holenstein, Thomas, Schuck, Marcel, Kolar, Johann Walter
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.01.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Air gaps; Bearingless slice motor; Coils (windings); Controllability; magnet-free motor; Magnetic flux; Magnetic levitation; Magnetism; Permanent magnet motors; Permanent magnets; Reluctance; Reluctance motors; Rotors; Stability; Stator windings; Stators; synchronous reluctance motor; Topology; topology benchmarking; wide air gap machines
• ISSN: 2644-1284; 2644-1284
• DOI: 10.1109/OJIES.2020.3011926

This paper presents a novel bearingless synchronous reluctance slice motor topology that contains no permanent magnets. The rotor with two iron poles and flux barriers is levitated and rotated through a stator winding system with six coils wired as two three-phase systems. A constant rotor-oriented magnetization current is applied to generate a magnetic bias flux. The system can be controlled similar to a bearingless permanent magnet synchronous slice motor and provides passive stabilization of axial and tilting movements of the rotor. The motor topology is discussed in detail and a prototype implementation is presented. Its performance with regard to passive properties, achievable torque, controllability, and wide air gap suitability is benchmarked against two other designs that contain permanent magnets either in the rotor or the stator. A loss analysis of all topologies is performed and suitable application areas are identified. The proposed design provides an interesting alternative to existing bearingless slice motor topologies in applications that require high rotational speeds, high process or ambient temperatures, or a disposable low-cost rotor with short exchange intervals.