A Review of High-Step-Up Non-Isolated DC–DC Converters Focusing on the Topology Methodology and Features

Power electronic converters are essential components in modern electrical systems, with dc–dc converters being particularly crucial for their extensive variety and widespread applications, notably in renewable energy systems and electric vehicles. For applications such as Photovoltaic (PV) arrays, fuel cells, and microgrids, a critical requirement is the need for non-isolated, high step-up dc–dc converters capable of providing a high-voltage gain while mitigating significant practical challenges, including high semiconductor stress and degraded efficiency at extreme duty cycles. This study proposes a comprehensive, structural-based review of over 100 non-isolated high step-up dc–dc converters, specifically excluding topologies that rely on coupled inductors. Our primary contribution is a novel categorization and comparative analysis framework that delves into the fundamental topological details and features, going beyond the focus of recently suggested reviews. The methodology begins with a systematic analysis of classical non-isolated converters (Boost, Buck-Boost, Ćuk, SEPIC, and Zeta) to establish a baseline and highlight their limitations, such as the semiconductor voltage stress being greater than the output voltage in most cases, which reduces their suitability for high-gain applications. The paper then systematically classifies advanced topologies into 23 distinct groups based on their unique structural characteristics. The comparison is rigorously quantitative and systematic, focusing on structural details and key performance metrics such as voltage gain and density, semiconductor stress, and current continuity and component count. The comprehensive analysis is conducted by deconstructing each topology into its constituent sub-converters to reveal how structural combinations influence key performance metrics. Finally, the findings facilitate a discussion on the practical applications of each topology, matching their inherent characteristics to specific real-world systems like PV arrays, Electric Vehicles (EVs), Vehicle-Integrated PV (VIPV) systems, and electrolyzers.