A Control Strategy for Bearingless Switched-Reluctance Motors

A bearingless switched-reluctance motor (BSRM) has a complicated nonlinear character; therefore, its control strategy is very important to a stable operation. This paper presents a new control strategy for rotating and levitating a 12/8 BSRM with two sets of windings. This strategy can enhance not only the availability of winding currents in producing the radial force to suspend a rotor, but also decrease the torque ripple and stator vibration. First, influences of different combinations of winding magnetomotive force on the radial suspension force and torque are analyzed, and the optimal combination of winding magnetomotive force is gained. Second, based on the optimal combination, the theoretical equations of winding currents are obtained. Consequently, this paper gives the flowchart to calculate the advanced angle and winding currents. Moreover, the torque ripple and stator vibration of BSRM in the new control strategy are analyzed. Finally, simulation model and control system of BSRM with 12/8 poles are designed. Dynamic simulation and experimental results proved the theoretic conclusions.