LLC resonant converter with wide input voltage and load range at fixed switching frequency

This paper presents high efficiency LLC resonant converter operating at the fixed switching frequency which is applied for PV PCS (Photovoltaic Power Conditioning System) with wide input-voltage variations. Operating modes and voltage gain analysis of LLC resonant converter with single and two resonant tanks are described. The secondary windings are connected in series for high output voltage as well as high power. The principle of operation modes, voltage gain analysis and efficiency are verified on a 700W for a single LLC resonant tank and a 1kW for two resonant tanks.