Decoupling principle, model and rotor design of a novel 12/4 bearingless switched reluctance motor

The torque control cannot be decoupled form the suspending force control, and the current in windings cannot be tracked and chopped, that are the reasons which restrict seriously operating improvement of the bearingless switched reluctance motor (BSRM). Based on different combinations of stator and rotor pole numbers, and reforming rotor structure, there is a novel 12/4 BSRM proposed in this paper, which can naturally realize the decoupling of torque and suspending force. The principle of operation for the BSRM is introduced in detail. Its suspending force expressions are given with a simple derivation process and the control methods of the BSRM is presented. In order to eliminate output torque dead zone for the 12/4 BSRM, a step rotor is designed for optimizing its torque characteristics, and the FE analysis proves its validity.