Dynamic average small signal model of the SAB converter

In this article the average small signal model of the Single Active Bridge (SAB) converter is obtained. This converter can operate in two different conduction modes, Discontinuous Conduction Mode (DCM) and Continuous Conduction Mode (CCM). The SAB and the Phase-Shifted Controlled Full Bridge (PSFB) converter when operating in DCM present the same static behavior if the value of the inductor of the SAB is the same as the value of the output inductor of the PSFB referred to the primary side of the transformer. This conclusion can be extrapolated from the static analysis to the dynamic average small signal model, as such a first order model is obtained for this operating mode. However, when the SAB converter operates in CCM, the current through the inductor does not start at zero at the beginning of the switching period. Both small signal models are analyzed and confirmed by means of simulations.