Modelling and analysis of the magnetic field radiated by a switching mode power supply

In this paper, we have analyzed the behaviour of a switched mode power supply (flyback) in radiated near-field. We have modelled it by equivalent diagrams representing electric operations, including the parasitic elements. First, we have tried to link the amplitude of the spectra of the radiated magnetic field with the electrical quantities (current and voltage) during the different working phases of the converter. Then, under some assumptions, we have proposed a model of the transformer with parasitic elements, which is valid up to 6 MHz. Finally, this model is used to model the complete structure. The parameters of the model are extracted from measurements and/or technical data of the components (semi-conductors). So, we can determine the dominant resonance frequencies of the structure which are significant in radiated mode.