Interleaved LLC resonant converter with integrated dual transformer for PV power systems

Abstract

This paper proposes a high step-up gain interleaved LLC resonant dc-dc converter with integrated dual transformers for photovoltaic power generation systems. It consists of a pair of power switches, LLC resonant tanks, power transformers and voltage doubler circuits. Power switches are connected in the form of a half-bridge network and interleaving converters are fed alternately by operating these power switches with interleaved half switching cycle. Both transformers including magnetizing and resonant inductors are realized on a single EE core, thereby increasing the power density. Voltage doubler circuits are connected at secondary windings to boost output voltage and to reduce parasitic capacitances of secondary windings. Due to interleaved structure of converter the voltage/current stress on resonant components is smaller. A 150-W laboratory prototype with output voltage 350-V and input voltage ranging from 40 to 60-V is built and tested to verify the operational principle and performance of the proposed converter.