High efficiency step‐up DC–DC converter for grid‐connected photovoltaic microinverter applications

This paper presents a resonant step‐up DC–DC converter for the photovoltaic micro‐inverter system and describes the converter's operation principle in detail. In the proposed converter, the active‐clamp technique is used to reduce the high voltage spike of the main power switch during its turns‐off. Meanwhile, the output rectifier diodes can operate in the zero‐current‐switching (ZCS) operation and the clamping power switch can operate in zero‐voltage‐switching (ZVS) condition with the series LC resonant circuit. Then, the design procedure for the key components of the proposed DC–DC converter is derived. Finally, experimental prototype with 300 W is established to verify the validity of the proposed topology, and the experimental results shows that the proposed topology processes the merits of few components, simple control, galvanic isolation and high conversion efficiency in a wide photovoltaic voltage input and power range.