Comparative performance analysis of bearingless switched reluctance motor

To solve the magnetic field coupling problem in the traditional bearingless permanent-magnet motor, which has magnets on the rotor, we propose two topologies of bearingless switched reluctance motors (BLSRMs) with magnets on the stator yoke. The first is a six/four-pole BLSRM with three pairs of permanent magnets on the stator and the second is a six/four-pole BLSRM with one pair of stator yoke magnets. First, the working principle of BLSRMs is introduced, including the structure and winding configuration, and the mechanism of generating levitation force is analyzed in detail. Based on 2D finite element analysis, the electromagnetic characteristics of the prototype are compared, including torque, suspension force, no-load back EMF, and no-load permanent magnet linkage. The calculation results show that at high speeds, the coupling between the levitation force winding and the torque winding of the BLSRM with one magnet pair is low, which allows for better decoupling performance and greater levitation force. In addition, although the motor with three pairs of permanent magnets in the stator yoke shows better torque performance, the loss of the motor is higher at a high speed. The research results lay a theoretical foundation for further research on a new type of bearingless motors.