Comparison of Two Auxiliary Suspension Winding Configurations for High-Speed SPMSM with Aerodynamic Bearings

Aerodynamic bearings are one type of non-contact bearings without air supply. However, the dry friction and the instability problem of the bearings put forward the need for external intervention. To provide the aerodynamic bearing with an external electromagnetic force, an auxiliary suspension winding is additionally inserted in the stator core slots of a surface-mounted permanent magnet synchronous motor (SPMSM), which works like that of the bearingless motor. To generate a controllable radial force, there are two topologies for the inserted auxiliary suspension winding. For a 4-armature-pole motor, the auxiliary suspension winding can be of either 2-pole or 6-pole. In this paper, auxiliary suspension winding structure and radial force generation principle in the 4-pole SPMSM are detailed, and comparison in several aspects between two different auxiliary suspension winding topologies for the same 4-pole SPMSM will be discussed. Moreover, analytical derivation and finite element method (FEM) verification are elaborated.