order to answer the absence of complete and realistic data on behalf of the industry, the knowledge of the behaviour of MnZn ferrite's which equip the cores of the components high frequency clearly progressed thanks to the contribution of a new method of characterisation of magnetic materials. Contrary to the standardised methods, this method, based to the measure oftwo complementary electric impedance, makes it possible to reach, at any frequency, the data permeability and permittivity complexes by means of simple analytical relations. With regard to the formulations by finite elements, the general formulations in 3D were rewritten with complex physical properties, using two types of potential: electric and magnetic potential. The two-dimensional cartesian and axe-symmetric hypotheses are also used. The coupling with the equations of the electric circuit of feeding is carried out by the method of the electric potentials integrated in time. This method generally used in 3D is adapted for the problems 2D. The problems of the stray capacities related to the effects of the electric interactions in high frequency are also presented. For modelling at raised frequencies, the influence of the magnetic field on the operation of the component is not negligible any more. A magnetic model becomes necessary in order to take account of the inductance of a component. Several recent studies on the effects of the electric magnetic interactions in high frequency are shown. Each method has like characteristic the need for the approximations, in the majority of the geometrical cases, compared to the problem which is primarily three-dimensional. A modelling by the finite element method using the axe-symmetric formulation coupled with the equations of electric circuit is proposed and adapted for an electromagnetic characterisation of the wound components
