Soft-Switching DC-DC Converter with Coupled Inductors for High Step-Up Applications

Abstract

The rapid expansion of renewable energy utilization, especially photovoltaic (PV) generation, has created a critical need for high-efficiency power conversion systems that can deliver large voltage step-up ratios while minimizing stress, ripple, and energy loss. Conventional boost converters are often constrained by extreme dutycycle operation, elevated device stress, and poor efficiency at high-gain levels, which ultimately compromise the reliability of the source and shorten the operational lifespan of PV modules. Motivated by these limitations, this thesis investigates, develops, and experimentally validates a series of advanced DC–DC converter topologies that collectively address the challenges of voltage gain, soft-switching, stress reduction, and ripple suppression.

Building upon eight published research contributions, the thesis introduces and analyzes multiple high-gain converter families, including switched-inductor, switched capacitor, quadratic boost, voltage-lift, hybrid, and interleaved structures. Each design is supported by rigorous mathematical modeling, steady-state and dynamic analysis, and comprehensive MATLAB/Simulink simulations. Key innovations include the integration of voltage-multiplier cells, coupled-inductor extensions, and passive snubber networks that achieve soft-switching conditions and distribute component stresses more evenly. Experimental prototypes of the proposed converters are implemented and tested, confirming theoretical predictions and delivering peak efficiencies above 95% under practical operating conditions. Measurements further verify significant input current ripple minimization, reduced switching and conduction losses, and improved voltage gain, thereby ensuring longer PV source lifespan and stable converter operation.

The collective results demonstrate that the proposed converter topologies substantially outperform conventional designs in terms of voltage gain, efficiency, and controllability. Beyond advancing the state of the art in power electronics, the thesis provides a unified framework for designing scalable, high-performance converters for renewable energy systems. These findings directly support the reliable integration of PV power into future smart grids, electric vehicles, and distributed generation systems, contributing to the broader goal of sustainable energy conversion.