Reconfigurable LLC Topology With Squeezed Frequency Span for High-Voltage Bus-Based Photovoltaic Systems

In high-voltage bus-based photovoltaic systems, an isolated dc/dc converter is required to link the wide range low-voltage solar panel and the high-voltage dc bus. In this letter, a novel LLC topology with reconfigurable voltage multiplier rectifier is proposed for use in such applications. Depending on different input voltages, its rectifier automatically switches among type-4, type-5, and type-6 voltage multiplier configurations. Thus, the switching frequency range can be effectively squeezed and the efficiency over wide input range can be enhanced. Zero voltage switching and zero current switching are realized among all power mosfets and all power diodes, respectively. A 300 W prototype converting a 25-50 V input to a 760 V bus is designed and tested both in steady state and dynamically. Both the circuit functionality and the theoretical analysis are verified by the experimental results. The prototype demonstrates 96.1% peak efficiency and good overall efficiency performance over a wide input range.