A simplified method of calculating axial force for a permanent magnetic bearing

Axial magnetic force is an important parameter for permanent magnetic bearing (PMB). Current mathematical models for modelling the magnetic force are too complicated on the basis of some assumptions. This article presents a simplified calculating model of the axial force for axially magnetized PMB using the typical method of magnetic conductance. In this method, the magnetic-reluctance coefficient needed is investigated with the parameter identification method. It shows that changing the structure parameters and magnet materials only affects the magnetic-reluctance coefficient in a comparatively small range. A test device for measuring the axial magnetic force of PMB is developed to verify the effectiveness of the simplified calculating method. The results show that the proposed method can clearly express the relation between the axial magnetic force and structure parameters of PMB and requires less computation cost when compared with previous conventional methods. In conclusion, the proposed method is simple and effective in computing the axial force for PMB.