A magnetic circuit model of eddy current loss for a magnetic thrust bearing (MTB) is presented based on the effective reluctance and the magnetic circuit theorem. Considering the skin effect of eddy current, the effective reluctance is introduced into the flux path, and the magnetic flux, coil impedance and eddy current loss are analysed. In addition, a harmonic analysis on the finite element method model of the MTB and the magnetic circuit model is conducted and the results are compared in consideration of such affecting factors as material non-linearity, leakage, and fringing flux. It shows that the magnetic flux and the coil impedance have the same frequency domain properties in the above two models. The eddy current losses derived from these two models agree well with the experimental results.

The eddy current loss, produced in the solid stator and thrust disk by a time-dependent field, limits the operation performance of magnetic thrust bearings. Therefore, the accurate modeling of eddy current loss is essential for them. This article presents an analytical model to calculate the eddy current loss for a magnetic thrust bearing. After dividing the magnetic thrust bearing into several parts according to flux distributions, the eddy current loss expression for each iron part is proposed by solving one-dimensional diffusion equations and integrating power density over the volume. As the boundary condition of the magnetic field problem, the surface magnetic field intensity is confirmed by a fractional transfer function. Finally, the validity of this model is verified by finite element method analysis and experimental measurements. Based on the above analysis and research, this modeling method can be used as a reference for the eddy current loss calculation of nonlaminated actuators.

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