Small signal ac equivalent circuit modelling of the series resonant converter

The small signal dynamics of the series resonant converter are investigated using an equivalent circuit modelling approach. The converter input and output ports behave essentially as nonideal current sources, so the most suitable form is the two-port y parameter model. Two such models are proposed: a continuous time version valid for low perturbation frequencies, aand a discrete time version which models the inherent sampling in the converter and is valid for any perturbation frequency less than the switching frequency. Experimental verification of the control to output transfer function and the output impedance is presented, and good agreement between theory and experiment is obtained.