Why a unique causality in the elementary commutation cell bond graph model of a power electronics converter

Power electronics converter modelling leads usually to define a multimodel representation due to the different states (ON and OFF) of the switching devices. The purpose of the paper is to show, through physical considerations and mathematical manipulations, how a unique model can be built, by using bond graph technique, causality properties and singular perturbation method. The study is made on the elementary commutation cell, and the proposed method is applied on a system corresponding to the association power converter-electrical load