A zero current switching non isolated bidirectional converter for interfacing energy storage devices with microgrids

Abstract

Energy storage devices (ESD) like batteries and supercapacitors are necessary for standalone microgrids. These ESDs are interfaced to the DC grid using bidirectional DC-DC converters. In an urban environment, where space is critical, a converter having small footprint is preferred. This necessitates a high switching frequency operation, which, in turn, increases the switching losses. To operate the converter at a high switching frequency while having low switching loss, soft switching is desired. For IGBT based converters, Zero Current Switching is the preferred mode for soft switching. In this paper, a zero current switching non isolated bidirectional converter employing two auxiliary switches for soft switching of the two main devices that form the power circuit of the bidirectional buck-boost converter has been proposed. The current stress on the main switches is only slightly increased as compared to a conventional bidirectional converter buck-boost converter. Simulation results are presented for the converter connecting two voltage sources while transferring power in either direction.