Abstract: One typical structure of axial active magnetic bearings(AMBs)was designed with the given diameters of the shaft and rotor thrust. The influence of the slot structure dimensions on the magnetic field distribution and the bearing force of axial AMB was simulated by using an electromagnetic finite element software when the radial airgap between the stator inner hole and the shaft was unchanged. And the error analysis was given by constructing a magnetic circuit model of the axial AMB. Given the chosen optimized slot dimensions, the influences of the radial airgap of the stator on the magnetic field distribution and the bearing force were analyzed with different rotor shaft diameters. The results showed that the bearing force increased first and then decreased with the increase of the ratio of the axial length to the radial length of the slot. The radial magnetic flux leakage was not the smallest when the ratio was between 5 and 10 but the bearing force was large and stable, and the biggest force was about 88.7% of the theory. With the increase of the ratio of the radial airgap to the axial suspended airgap(airgap ratio), the bearing force increased, but the increment was getting smaller. When the airgap ratio was 13.3, the simulated bearing force was 97.0% of the theory. When the airgap ratio was more than 13.3, the increment of the bearing force was very limited, so the impact was not significant.

Key words: electromagnetic force, magnetic flux leakage, slot structure, axial active magnetic bearing, optimization design