Research on photovoltaic grid-connected inverter based on soft-switching interleaved flyback converter

A grid-connected photovoltaic inverter based on interleaved flyback converter and a novel control strategy with BCM and soft switching are proposed in this paper. Power rating of the inverter can be dramatically increased due to the fact that the peak rated power of each of N interleaved flyback converter is 2/N of the total rated power. In order to increase the efficiency of the converter by eliminating the impact of leak inductance of the flyback transformer, inherited from the low voltage input and high voltage output applications, a leak inductance energy recovery circuit is proposed to restore the leak inductance energy and to achieve active clamping and resonant ZVS of the main switch at the same time. It is therefore possible to use flyback converters in higher power rating applications, as the N interleaved converters share the same leak inductance energy recovery circuit. In-depth analysis is presented on overall principal, variable switching frequency BCM and resonant ZVS with experimental results given. The proposed converter exhibits satisfactory character of high efficiency, simple topology, robust control and high reliability.