Analysis of a High Step-up Boost-Flyback Converter for Solar Energy Applications

In this paper an interleaved boost-flyback converter which was suitable for network connections of renewable energy sources is presented. Because in the solar system applications, level difference of the converter input and output voltage is high, boost converter cannot be used. Due to problems of the boost converter such as hard switching, voltage stress is equal to the output voltage. As regards in electronic converters, the power tends to increase the switching frequency to improve the converter response and increase its power density, hard switching caused to reduce converter efficiency. Also high voltage stresses of components have forced the designer to use semiconductor elements which can withstand in high voltage which will increase the losses in the converter and reduce its output. The proposed converter using LC resonant tank and auxiliary switches provides soft switching condition (ZCS) for the main converter. Interleaved techniques have used for reducing input current ripple and increase the size of the output capacitor and also boost-flyback converter have used to enhance converter gain and reduction of voltage stress of semiconductor components. The operating principle of the proposed converter is presented in this paper.