Numerical approach to study layout influence on electromagnetic emissions signature

Several elements have significant influence on the conducted disturbances of power electronic circuits, such as parasitic elements of the printed board layout and active and passive components. This paper treats the impact of a DC-DC buck converter layout on the Electromagnetic Interference (EMI). Two different routing designs for a chopper circuit are presented. A numerical modelling method is proposed to extract the equivalent circuit for each routing. Using the ANSYS Q3D extractor, based on the combination of the Moment method (MoM) and the finite-element methods (FEMs), the R, L, C matrices are computed for different frequencies. The obtained equivalent models, taking into account all the stray elements, are implemented on Simplorer. Indeed, the complete circuit, designed on this time domain simulator, is constituted by the equivalent circuit layout, the Line Impedance Stabilization Network (LISN) module, and the equivalent electrical model of the passive and active components. Afterwards, conducted disturbances were analytically identified. To validate the simulation results, experiments were performed. A comparative study is carried out in order to quantify the impact of the routing on the EM compatibility signature. A good agreement is obtained.