Principle and decoupling control of single winding bearingless switched reluctance motors

The operation principle of a new single winding bearingless switched reluctance motor was analyzed. In view of the characteristics of nonlinearity and strong-coupling between instant levitation force and instant torque of this motor, the two-phase-excitation based decoupling control strategy was proposed, by which instant levitation force and average torque were produced by different phases. The mathematical models of levitation force and torque in a phase cycle were built. According to the feature that the average torque of each phase generated in the suspension region equaled zero, this two-phase-excitation decoupling control strategy was presented. To increase response speed of the levitation force subsystem and the motor's dynamic performance, optimal control methods of chopped current amplitude and turn-off angle were proposed. The simulation and experiment on the test motor were carried out, which proved that the proposed control strategy is effective and the closed-loop system has satisfactorily dynamic, and static performances.