Analysis of inductance characteristics for a bearingless permanent magnet synchronous motor.

In this paper, the inductance characteristics of a 2-pole surface-mounted bearingless permanent magnet synchronous motor (BPMSM) with 4-pole suspension force windings are investigated based on theoretical analysis and experimental investigation. Firstly, the winding configuration and operation principle of the BPMSM are presented. Secondly, the static and incremental inductances are defined. Then, based on the finite element (FE) analysis method, the static inductances of torque windings and suspension force windings in stator static coordinate reference are researched. In addition, the d- and q-axes static inductances in rotor revolving coordinate reference are obtained by 3/2 Transformation. Furthermore, taking the torque windings as an example, the incremental inductance of torque windings is studied, and the validity of the theory is confirmed by comparing the static and incremental inductances. Finally, the experimental study is carried out to verify the discussed numerical analysis. The results are helpful to measure parameters and build the mathematic model of BPMSMs, and lay a foundation for the further research on BPMSMs. [ABSTRACT FROM AUTHOR]