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This paper presents a comprehensive theoretical analysis and experimental results for three-level isolated dc-dc converter based on the single-ended primary-inductance converter (SEPIC) topology. The main advantage of this structure is the reduction of voltage stress on semiconductors comparing it to the conventional SEPIC converter. Voltage stress is the major challenge associated with the conventional SEPIC structure, and contributions in this area can extend the range of applications for the family of SEPIC converters. The analyzed structure contains two switches, and their commands can be either equal or phase-shifted by 180 . This provides four different modes of operation in discontinuous conduction mode (DCM), which have different operating stages, waveforms, and design equations. In this paper, the topology with parallelconnected output and the static and dynamic theoretical analysis in DCM, for the four command signal profiles, are presented. The advantages and disadvantages, control strategy, experimental results, and a comparative analysis with the conventional SEPIC converter are discussed. The dc-dc SEPIC converter was verified by experimental results from a proof-of-concept prototype with 500 W rated power, 400 V input voltage, 120 V output voltage, and 50 kHz switching frequency. The converter achieved 94.72% efficiency at rated power.

Resumo-Este trabalho propõem uma topologia baseada no conversor CC-CC SEPIC convencional isolado. A topologia proposta reduz os esforços de tensão sobre os interruptores e diodos e promove a divisão de corrente nos diodos do estágio de saída quando comparada com o conversor SEPIC convencional. Estas características ampliam a faixa de tensão e potência dos conversores da família SEPIC. O artigo apresenta a topologia, etapas de operação, análise teórica no modo de condução descontínuo (MCD), metodologia de projeto, resultados experimentais com um circuito de grampeamento passivo dissipativo e análise comparativa com o conversor SEPIC convencional. O conversor CC-CC proposto foi validado em um protótipo de 500 W de potência de saída, 400 V de tensão de entrada, 120 V de tensão de saída e 50 kHz de frequência de comutação. O conversor atingiu 91,87% de rendimento em potência nominal. Palavras-chave-Conversor CC-CC, Conversor SEPIC, Modo de condução descontínuo, Reduzidos esforços nos semicondutores.

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