Nonlinear identification of electro-magnetic force model

Conventional attractive magnetic force models (proportional to the coil current squared and inversely proportional to the gap squared) cannot simulate the nonlinear responses of magnetic bearings in the presence of electromagnetic losses, flux leakage or saturation of iron. In this paper, based on results from an experimental set-up designed to study magnetic force, a novel parametric model is presented in the form of a nonlinear polynomial with unknown coefficients. The parameters of the proposed model are identified using the weighted residual method. Validations of the model identified were performed by comparing the results in time and frequency domains. The results show a good correlation between experiments and numerical simulations.