Isolated Bidirectional DC/DC Converter for LVDC Grid

This paper proposes an isolated bidirectional DC/DC converter designed for LVDC grid with bipolar output. A dual active bridge (DAB) converter has been widely studied and applied for isolated bidirectional DC/DC converter, although limitation of input and output voltage range. In order to overcome the weakness of a DAB converter, the proposed converter is composed of an input series output series (ISOS) buck-boost converter and a DAB converter. The ISOS buck-boost converter is formed by connecting buck-boost converters in series with the wide input and output voltage range. The DAB converter, which consists of a 3-level neutral point clamp (NPC) topology and a transformer for isolation, is responsible for bidirectional power control. The bipolar voltage outputs are provided using isolated and series connected two outputs, enabling independent power control. In this paper, the performance and feasibility of the proposed converter are experimentally verified through hardware implementation.