Islanded dc Microgrid Design Using Non-Isolated Bidirectional Interleaved Half Bridge Converter for Energy Storage Application in a dc Microgrid

Abstract

This paper presents a performance evaluation of non-isolated bidirectional interleaved DC converter compare to conventional half bridge as an interface between DC bus and battery energy storage system (BESS) for energy storage application in a DC Micro-grid. Islanded DC Micro-grid is implemented using multiple energy storage elements in parallel to ensure redundancy, reliability, and modularity. The conventional Half Bridge converter is compared with the interleaved topology (which is obtained by increasing the phase legs of half bridge) in terms of their frequency response analysis and SoC discharge when employed as interfacing converter between BESS and DC bus. The small signal or frequency response analysis is performed in Plecs using AC sweep, impulse response and multitoned analysis. It is established in this study from the open loop bode diagrams of the converters that the corner frequency of the interleaved is almost two times the half-bridge. This difference affected their SoC discharge when employed in a Micro-grid with the interleaved discharging at a rate almost twice that of half bridge. The interleaved also provides reduced current stress on the switch making it best suited for high power applications. The DC bus is 48V dc with a load power of 400W.