A Modified Z-Source based Non-Isolated High Step-up Converter with Reduced Device Count

Abstract

High step-up dc-dc converters are predominantly used for interfacing low-voltage renewable sources including solar photovoltaic (SPV), fuel-cells, and DC microgrid. Several high gain topologies reported in the literature to integrate such sources, however, suffer from issues such as limited voltage boosting factor, higher device voltage stress, inability to deal with wide input voltage variations, increased device count, discontinuous input current, and so on. To address the aforementioned limitations, this article proposes a modified high gain converter. This is achieved by methodically adjusting the Z-source (ZS) converter to obtain high gain while lowering voltage stress and device count. As a result, switches with lower on-state resistance <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(R_{ds(on)})$</tex> are employed, which facilitates reduced switching losses and enhanced efficiency. Furthermore, while drawing continuous input current, the converter has improved efficiency at lower duty ratios, which is a crucial aspect of an SPV interface converter. The implemented topology performed well when compared to similar recent topologies. Eventually, experimental waveforms validate the theoretical claims and analysis. A 93.5% peak converter efficiency has been obtained.