FEM-3D application for modelling and design of Epstein frame

A new approach for numerical modelling and design of the prototype of the Epstein frame is presented. A mathematical model and an original algorithm for the non-linear and iterative calculation by using FEM-3D of the Epstein frame is given. Calculations of the magnetic field distribution are carried out for various magnetic polarizations and for three different grades of specimen of electrical steel sheet by considering the anisotrophy. For the design of the air-flux compensation coil of the Epstein frame, the leakage fluxes under different current loads and different grades of specimen are calculated. Numerical calculation of fluxes and magnetic polarization is carried out by using numerical integration of the magnetic vector potential calculated by FEM-3D. The effective magnetic path length l(m) depends on the magnetic polarization and the type of specimen. The computational values are compared to the experimental results obtained by the prototype of the Epstein frame.