LCLC Resonant Converter for Solar PV to Grid Application

Abstract

An efficient DC-DC power converter capable of operating for wide input variation is essential for applications involving PV based systems. This is due to changes in irradiation, partial shading, temperature, and many other conditions resulting in large fluctuations in PV voltage. Additionally, the converter should be able to give high steady state gain while operating at minimum input voltage. In this work, a high gain LCLC resonant converter with reduced transformer turns ratio, and high power conversion efficiency is considered for solar photovoltaic (PV) to grid application. The presence of a voltage doubler secondary ensures a reduced turns ratio results in a smaller transformer size and minimizes the transformer parasitic. Frequency and phase shift control based hybrid modulation technique is incorporated to establish high voltage dc bus from wide varying PV source. The converter is analysed theoretically at various operating modes and the performance is evaluated with the help of a 500 W experimental prototype.