Novel soft-switching high voltage gain converter with quasi-resonant boost stages

To connect low voltage renewable energy sources to the DC bus of a power microgrid system for wider applications, a high efficiency, high step-up, and reasonably priced dc-dc converter is in need as an interface. In this study, a novel high voltage gain dc-dc converter with series LC quasi-resonant boost stages is proposed. Three resonant loops with quasi-resonant operation are used to achieve a high gain with a low duty cycle. All three of the diodes can turn off with zero current switching (ZCS), which avoids the reverse recovery problem. In addition, both of the switches achieve the zero voltage switching (ZVS) condition. The circulating current used to achieve soft-switching is recycled by the output capacitor. The voltage gain can be further improved when soft-switching is not considered, which is of practical use in the case of an emergency. Moreover, the input source, the output, and the switches have a common ground to help simplify the driver of the switches and to expand the scope of transformer-less applications. The operation principle and a mathematical analysis of the proposed topology have been described in detail in this study. In addition, a 200 W prototype is built and tested to verify the main features of the proposed converter.