Abstract: Five mathematical models of the permanent magnet bearings are compared. And the methods for modeling are shown. The examples of the calculation of the parameters of radial magnetic bearings are presented. It is found that there is difference between the axial force and the radial stiffness of the axial magnetization radial magnetic bearing and these of the radial magnetization one, when the shape, the dimensions and the intensity of magnetization are same. The universal model is only suitable for the case of all the magnetic ring section dimensions are very small in comparison with the ring radius, and those are less than or equal to the gap between the two rings. The universal model ignores the effects of the curvature on the accuracy of the calculation, and deals with the magnetic rings as infinite long line magnets. The characteristics of the radial stiffness and the axial force varying according to the change of the relative position between the static ring and the rotor ring can be described well if the numerical integral model, which is based on the method of equivalent charges of magnetism and the direction of magnetization, is adopted.

Key words: Mathematic model, Method of equivalent charges of magnetism, Permanent magnet bearing, Permanent magnets