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Generating sources of renewable systems, like photovoltaic module or fuel cell, have a low‐output voltage that has to be boosted for most of applications, such as grid‐tie inverters. To accomplish this, an isolated DC–DC high step‐up single‐ended primary‐inductor converter (SEPIC) with a Greinacher voltage doubler cell is presented. It has the advantage of continuous input current, high efficiency, and high‐voltage gain and isolation and demands a single switch, being suitable for low‐power grid‐tie photovoltaic systems. The operating principles and steady‐state analysis are presented, including the detailed analysis of resonant stage, and the effects of transformer winding capacitances on converter operation are investigated. Moreover, the effects of resonance frequency variations on converter efficiency are experimentally investigated. Experimental results on a 50 kHz and 200 W prototype are presented to validate the proposed concept. [ABSTRACT FROM AUTHOR]

High step‐up converters are often used in photovoltaic applications due to low voltage of photovoltaic modules. In this paper, two new topologies, obtained with the insertion of voltage multiplier cells on secondary side of isolated SEPIC, are proposed. They have the advantages of continuous input current, isolation, high efficiency, and high voltage gain, being suitable for low power applications. To perform this study, theoretical and comparative analyses are accomplished. They include a description of each converter, tables, and curves with relevant information, such as voltage gain, total voltage stress, and total current stress. Moreover, the identification of the use of coupled inductor or transformer based on the analysis of DC magnetizing current is presented. Theoretical analysis and experimental results on 37.4/400 V, 50 kHz, and 200 W prototypes of selected isolated SEPIC with voltage doubler cell and voltage quadrupler cell are presented to validate the proposed topology and concept, where the maximum efficiency obtained for the converter with doubler cell is 96.85%, while for the converter with quadrupler cell is 97.75%. [ABSTRACT FROM AUTHOR]