Multiple Resonance Prediction Through Lumped-Parameter Modeling of Transformers in High-Frequency Applications

The accurate prediction of coupled inductive and capacitive effects in electromagnetic coils is of crucial importance in many industrial applications, due to the increase in operating frequency or the increase in voltage levels. In this article, we propose a lightweight coupled electric circuit model that avoids solving a large 3-D Maxwell full-wave problem and is still able to predict not only the first resonance but also the next few resonances as accurately as experimental characterizations would do. The resistive, inductive, and capacitive lumped circuit parameters of the magnetic device are identified by means of 2-D finite element (FE) modeling, and then implemented in an electric circuit that realizes the inductive–capacitive coupling. Moreover, the lumped parameter identification can be performed at different levels of representation of electromagnetic coils, from turn level to winding level, to resolve additional resonances of the system, still keeping the computational complexity compatible with industrial design requirements. The efficiency of the method is confirmed by means of simulations and measurements performed on a high-frequency transformer and on an air inductance.