Interleaving double-switch buck-boost converter

The double-switch buck-boost converter, characterised with non-inverting and step-up/step-down conversion, is suitable for the front stage of the two-stage photovoltaic (PV) grid-connected inverter. However, one strategy for the converter, named as ´synchronisation control´, requires a considerable inductor and another control strategy, named as ´combined control´, is sophisticated to control the operation modes transition smoothly. In order to reduce the inductance in synchronisation control strategy and to resolve the control complexity in combined control strategy, an interleaving control strategy for a double-switch buck-boost converter is proposed. This paper analyses the operation principle and characteristics of the proposed control strategy, and compares several switching strategies. Finally, the interleaving operation principle is verified by a 3-kW two-stage PV grid-connected inverter prototype.