Flux saturation of switched reluctance motors (SRMs) and severe non‐linear relationship between current, position angles and electromagnetic torque lead to the difficulty of torque modelling and analysis. Specifically, the permeability of ferromagnetic material varies with the magnetic field strength H , and the core saturation effect increases with H . In this study, piecewise curve fitting method is adopted for analysing the relationship between the permeability and the stator winding current. The magnetic equivalent circuit method is adopted to build an analytical model for a SRM where the saturation of ferromagnetic material is expressed in the form of variable permeance. The comparison between computation results of analytical model and finite‐element method simulation results verifies the correctness of the proposed model. Simulation and experimental research of a SRM speed control system verify the practicability of the model.

The article proposes a single-phase suspension control strategy with self-decoupling to address the complexity of decoupling control strategies caused by the coupling between radial suspension forces in two radial directions of bearingless switched reluctance motor (BSRM). The proposed single-phase control strategy aims to achieve stable rotor suspension by adjusting the current of the suspension winding only when one of the torque windings is excited instead of all torque wingdings. A sharing suspension windings bearingless switched reluctance motor (SSW-BSRM) is taken as research objective, the relationship between radial force and radial displacement of rotor with proposed single-phase suspension control strategy in one electrical cycle is analyzed. When the rotor speed exceeds a certain value, the feasibility of switching from three-phase suspension control to single-phase suspension control is theoretically analyzed. The expression of the critical speed of the rotor is derived, which reveals the speed requirement for achieving stable rotor suspension under the proposed single-phase suspension control strategy. The simulation and experiment are carried out on a 12/8 SSW-BSRM, and the results verify the effectiveness of the proposed single-phase control strategy in achieving stabilized rotor suspension with self-decoupling in two radial directions. Furthermore, the proposed control strategy can also be applied to the suspension control of conventional BSRMs.

As its name indicates, the bearingless switched reluctance motor does not have windings or permanent magnets on the rotor. This has the advantages of simple structure, high reliability and easy control. The sharing-suspension-windings bearingless switched reluctance motor inherits the above characteristics, and has obvious advantages in the research field of bearingless motors with its motor structure of decoupling torque and radial force. In this paper, the sharing-suspension-windings bearingless switched reluctance motor is taken as the research object. The finite element model of the sharing-suspension-windings bearingless switched reluctance prototype is established. The electromagnetic characteristics of the prototype are analyzed. As the premise of motor suspension, the structural decoupling of torque and radial force is analyzed and experimentally verified. Then, the flux-linkage saturation of the motor is derived at the position where the stator and rotor are completely aligned and the stator and rotor are completely unaligned. The torque model of the motor is derived based on the flux-linkage saturation, and the accuracy of the model is verified by the fitting comparison between the theory and the finite element simulation. It lays a theoretical foundation for the subsequent structure optimization design research of the sharing-suspension-windings bearingless switched reluctance motor.