Buck converter associated with active clamp flyback converter for PV power system

This paper presents an LED lighting system with a PV source. The circuit structure of the proposed system separately adopts buck converter and flyback converter as the charger and discharger. With this circuit structure, buck converter can vary its duty ratio to regulate charging current of battery, while flyback converter with active clamp circuit can recover energy stored in leakage inductor of transformer to drive LED lighting. To simplify the circuit structure, switches of two converters are integrated with a synchronous switch technique. With this approach, the proposed system has several merits, which are a less component counts, lighter weight, smaller size and higher conversion efficiency. As compared with the conventional converter with hard-switching circuit, the proposed one can improve conversion efficiency of 7% and achieve efficiency about 83% under full load when the proposed system is operated in the driving LED condition. Experimental results obtained from a prototype with the output voltage of 10 V and output power of 20 W have been implemented to verify its feasibility.