Recent advances of step-up multi-stage DC-DC converters: A review on classifications, structures and grid applications
Mahdi Abolghasemi, Iman Soltani, Mojtaba Shivaie, Hani Vahedi
Abstract
In the contemporary landscape of trend industries including sustainable energy sources, high-voltage direct current, and electrified mobility, the need for power conversion units to bridge disparate sections is felt more than ever before. Among these conversion units, the step-up DC-DC converters occupy a pivotal role, elevating the DC voltage levels and facilitating interactions between converters and circuits. However, the multistage DC-DC converters, prevalent in large-scale industries, offer higher voltage gains and power density. This review paper has categorized the multistage DC-DC converters into isolated/non-isolated, voltage-fed/current-fed, unidirectional/bidirectional, hard-switched/soft-switched, and step-up/step-down configurations. It has been followed by a brief review of various voltage boosting techniques, containing an analysis of multi-staging voltage boosting methods and recent advances in converter structures. Then, the multistage DC-DC converters have been classified into several distinct categories: quadratic gain, cascaded, interleaved, modular, multilevel, and hybrid structures. Recent advancements and developments in each of these categories have been meticulously examined, with a focus on their fundamental concepts, advantages, and disadvantages. In particular, the voltage gains, voltage stresses, and current stresses associated with quadratic gain and cascaded DC-DC converters have been analyzed and compared in detail. Furthermore, an in-depth exploration of the structures and configurations of interleaved, modular, and multilevel DC-DC converters has been conducted. This includes a discussion on the combinations of modules, the benefits arising from these integrations, and insights for future developments. The applications of each category of multistage DC-DC converters across various industries—particularly in grid applications—have been thoroughly analyzed. Subsequently, these converters have been evaluated based on several criteria: reliability, component count, control complexity, voltage gain, power level, cost, and weight. The prioritization of these factors has also been systematically presented.