Topologies and Design Characteristics of Isolated High Step-Up DC–DC Converters for Photovoltaic Systems

This paper aims to investigate the state-of-the-art isolated high-step-up DC–DC topologies developed for photovoltaic (PV) systems. This study categorises the topologies into transformer-based and coupled inductor-based converters, as well as compares them in terms of various parameters such as component count, cost, voltage conversion ratio, efficiency, voltage stress, input current ripple, switching mode, and power rating. The majority of the topologies examined exhibit peak efficiencies of 90% to 97%, with voltage conversions in excess of eight, as well as power ratings ranging from 100 W to 2 kW. The existing literature has found that most isolated DC–DC converters increase their turn ratios in order to achieve high step-up ratios. As a result, voltage spikes have increased significantly in switches, resulting in a decrease in overall system efficiency. In this research, the use of passive and active snubbers to provide soft switching in isolated step-up DC–DC converters is investigated. Moreover, a comprehensive analysis of the three most widely used boost techniques is provided. A reduction in turn ratio and a decrease in voltage stress were the results of this process. The main purpose of this study is to provide a comprehensive overview of the most used high-boost isolated DC–DC topologies in PV systems, including flyback, isolated SEPIC, forward, push-pull, half- and full-bridge, and resonant converter, with a focus on the recent research in the field and the recent advancements in these topologies. This study aims to guide further research and analysis in selecting appropriately isolated topologies for PV systems.