Synchronous reluctance type bearingless motors with multi-flux barriers

Bearingless motors (BeIMs) are characterized by integration of electrical motors and magnetic bearings. Therefore, rotor shaft suspension can be realized without mechanical contacts or lubrication. In addition to advantages of conventional magnetic bearings, these motors are expected to have advantageous features such as small size, low cost and high critical speed. Accordingly, the various types of BeIMs have been proposed and developed among researchers and industrial engineers. In these motors, the authors have studied the synchronous reluctance type BeIM (SynReI BeIM). In previous papers, the SynReI BeIM of the rotor structure with salient-pole form has already been proposed. However, no studies have ever tried to examine the optimal rotor structure producing torque and suspension force effectively. On the other hands, the rotor structure with multi-flux barriers has been reported as rotor structure with good torque characteristics in general synchronous reluctance motors. Thus, this paper discusses the optimal rotor structure of the SynReI BeIM, and it is shown with 2D-FEA that the rotor structure with multi-flux barriers is effective in producing torque and suspension force in the SynReI BeIM.