A new approach for determination of eddy current and flux penetration in nonlinear ferromagnetic materials

A new approach, based on the magnetic vector potential, is developed for the solution of flux penetration and eddy current problems in nonlinear ferromagnetic materials. The model obtained for this diffusion problem is useful in the sinusoidal time varying cases, and can be extended to the general time varying cases. The model is applied to the problem of flux penetration and determination of losses in ferromagnetic bars used for starting and damping in large synchronous motors and generators. These machines are mostly found in hydro-electric pumped storage power stations. The results consist of real and reactive power losses, equivalent resistance and reactance, distribution of induced currents and flux penetration. A comparison of results with previous authors´ work is given. Good agreement between experimental results and simulated ones is established concerning loss calculations. The developed method is best suited for use in cases involving complicated contours of ferromagnetic materials and general boundary conditions. Therefore, the method is useful in rotating machine applications.