Compensation control of axial force for conical bearingless switched reluctance motors

Conical bearingless switched reluctance motors (CBSRMs) can provide axial forces for 5-Degree-Of-Freedom (5-DOF) magnetic levitation driving system. The electromagnetic field of the CBSRM is so complicated that the electromagnetic forces are difficult to control including torque and levitation forces. In this paper, a compensation control of the axial force is proposed to simplify the current algorithm for CBSRMs. The currents of two normal conducted phases are regulated to provide torque and radial forces, and the third phase is controlled to compensate the axial force. Thus, radial forces, axial force and torque can be controlled independently so that the rotor can achieve 5-DOF magnetic levitation. The simulation results verify the demonstrated performance.