Influence of the armature current on suspension characteristics of a new bearingless doubly salient electro-magnetic motor

The new bearingless doubly salient electro-magnetic motor (BDSEM) with independent dc suspension windings in stator has the advantages of robust structure, and is suitable for high speed application in high temperature environment. The angular position detection is eliminated for suspension force control which decreases the complication and increases the reliability. Although the coupling between suspension force control and torque control is reduced significantly, the armature current has influence on suspension characteristics. In this paper, the influence of the armature current is analyzed by finite element (FE) method. The bias magnetic flux produced by the field current is changed by the armature current. The torque characteristic is also investigated to verify that the suspension current has little influence on the torque.