A Possible Output Area of Torque and Suspension Force in a Switched Reluctance Type Bearingless Motor with One Phase Excitation

Switched reluctance type bearingless motors are characterized by integration of switched reluctance motors and magnetic bearings. Therefore, these motors can control radial rotor positions with magnetic force actively. Production of suspension force for rotor shaft magnetic suspension is explained with differential stator windings. In the previous paper, accurate theoretical formulae of instantaneous torque and suspension force generated by one phase excitation were derived from an assumption of simple permeance distribution. From the derived theoretical formulae, it is found that there exist cross coupling between the instantaneous torque and the suspension force. This paper derives a possible output area of the instantaneous torque and the suspension force considering the cross coupling in order to realize a stable operation. It is shown with experimental results that the possible output area of the proposed motors is very accurate in terms of practical application.