The effect of magnet thickness on maximum levitation force in surface permanent magnet synchronous bearingless motor

In this paper, the principle of levitation force production for surface permanent magnet synchronous bearingless motors (SPMSBM) is introduced. The relationship of levitation force, magnet thickness and air-gap length in the SPMSBM was found based on the levitation force analytical model. The optimal thickness of permanent magnet to obtain the maximum controllable levitation force was studied and a function C is proposed to determine the optimal magnet thickness instead of finite element analysis (FEA). The result was confirmed by FEA.