Dynamic eccentricity in single-rotor single-stator axial flux permanent magnet synchronous machine with parallel path windings

Axial flux PM machines (AFPM) are widely used in elevators, in-wheel drive and wind turbine applications for its advantages such as high torque density, short axial length and compact construction, etc. Different with radial flux machines, the performance of AFPMs are easily affected by rotor eccentricity, since the appealing force in axial direction between stator and rotor disk is huge in AFPMs, especially in single rotor - single stator AFPM, where the force can´t be counteracted as in case of double-stator single rotor topology. This paper studies the effect of rotor dynamic eccentricity to performance in a single-rotor single-stator AFPM using transient three-dimensional(3D) electromagnetic finite-element-analysis (FEA). The structure of machine and definition of eccentricity was illustrated, where the details defined as the angle between symmetric axis of stator bore and symmetric axis of rotor disk.