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This paper presents a multilevel step-up dc/dc converter for dc-grid-based offshore wind energy conversion applications. The main features of the proposed multilevel converter are as follows: 1) the voltage stress of the power devices can be reduced, making it suitable for high-voltage applications; 2) the boost inductor can be reduced significantly, leading to the outstanding dynamic performance; and 3) high-voltage gain can be obtained and thus is well-suited for high-gain applications. Theoretical analysis was carried out for a four-level step-up converter, based on which, the converter can be extended to any arbitrary number of levels. The proposed four-level converter was verified by a simulation and evaluated by comparing with a conventional multilevel dc/dc converter in terms of the component stress and power device count. The developed topology was implemented on a 2-kW prototype converter to evaluate its feasibility. [ABSTRACT FROM AUTHOR]

This paper presents a high-efficiency multilevel flying-capacitor (FC) dc/dc power conversion with a lower passive component rating and power device count for distributed renewable energy systems. A resonant technique is adopted for the proposed dc/dc converter to achieve zero-current switching (ZCS) for all switches. Theoretical analysis is carried out for the proposed quintuple topology with three active switches. The proposed converter is evaluated to the conventional FC converter, in terms of the component rating and count, to highlight its advantages with respect to the power density and cost. The experimental results of a 1-kW prototype FC converter are presented to validate the theoretical analysis and principles, as well as attest the feasibility of the proposed topologies. [ABSTRACT FROM PUBLISHER]