High Efficiency High Step-up Isolated DC-DC Converter for Photovoltaic Applications

A high efficiency and high step-up isolated DC-DC converter with a new topology configuration for photovoltaic (PV) application is proposed in this paper. This converter consists of a Zero-Voltage-Switching (ZVS) and Zero-Current-Switching (ZCS) current-fed push-pull converter as a DC transformer dealing with most of power and an active clamp flyback (ACF) converter as a regulator with considerable high efficiency within a large conversion range. The two converters are constructed with the input-parallel-output-series (IPOS) structure. The input-parallel connection is able to share the large input current as well as reduce the current ripple, while the output-series connection is used to increase the output voltage gain. A 400 V / 400 W experimental prototype with an input voltage range of 24 V - 32 V is built. The maximum efficiency reaches at 95.1%. The experimental result validates the correctness of the analysis and proves the feasibility of the proposed topology for the photovoltaic applications.