Characteristics Analysis and Comparison of Conventional and Segmental Rotor Type 12/8 Double Stator Bearingless Switched Reluctance Motors

A novel segmental rotor type 12/8 double stator bearingless switched reluctance motor (DSBSRM) is proposed in this paper. The proposed DSBSRM includes six parts: outer stator, rotor, inner stator, shaft, torque and suspending force windings. Although the function of outer and inner stators of the proposed DSBSRM is the same as that of conventional 12/8 DSBSRM, unlike conventional 12/8 DSBSRM, the outer stator of the proposed DSBSRM has two types of stator poles: exciting and auxiliary poles. Moreover, the rotor of the proposed DSBSRM does not have any mechanical saliency, and it is composed of rotor segments, nonmagnetic isolator and toroidal core. The rotor segments and toroidal core are embedded in the outside and inside of the nonmagnetic isolator, respectively. Due to particularity of the structure, the proposed DSBSRM operates in short flux paths, and fluxes produced from the torque and suspending force windings are independent from each other. Therefore, compared with conventional 12/8 DSBSRM, the proposed DSBSRM not only improves the output torque density, but also has better decoupling characteristics between torque and suspending force control. To verify the proposed structure, finite element method (FEM) is employed to get the characteristics of the proposed DSBSRM. Meanwhile, a conventional 12/8 DSBSRM is also analyzed for comparison. Finally, the validity of proposed structure is verified by simulation results.