Abstract: Researches on the hybrid magnetic bearings are mainly based on the equivalent magnetic circuit method. However, this method is mostly based on a series of assumptions, and those assumptions are untenable in large-air-gap hybrid magnetic bearings, the application of the equivalent magnetic circuit method will be restricted, and the application of hybrid magnetic bearings on large-air-gap situation will be limited. Therefore, the bearing capacity model of large-air-gap hybrid magnetic bearings needs to be studied. In this study, the application area of the equivalent magnetic circuit method during different dimension of air gap has been studied by using ANSYS, and error factors of the equivalent magnetic circuit method when the dimension of air gap increased are analyzed. An analysis method of leakage fluxes in air gap has been used, and the modified bearing capacity model based on leakage fluxes has been built. The modified bearing capacity model has been tested by using ANSYS and experiment.

Key words: bearing capacity, equivalent magnetic circuit, hybrid magnetic bearings, large-air-gap, leakage fluxes