Small-signal modeling of the interleaved boost with coupled inductors converter

This paper aims to investigate the dynamic behavior of an isolated converter topology suitable for high step-up applications, i.e the Interleaved Boost with Coupled Inductors (IBCI). Such topology, presented in literature with the alternative name of active-clamp flyback-forward converter, has interesting characteristics such as continuous input current, soft-switching operation in a wide load range and high step-up capability with limited switch voltage stress. While the converter steady-state operation is well understood, its dynamic behavior still needs investigation. The purpose of this paper is to fill this gap by proposing a non-linear average model that, under small-signal approximation, can be linearized around a given operating point. Different transfer functions are then derived, that allow an exhaustive converter dynamic analysis. Experimental measurements, taken on a 300 W prototype, verify the theoretical forecasts.