Performance analysis of a bidirectional DC-DC converter for grid-connected energy storage applications

Abstract

The aim of this report is to design, model and analyse the performance of a high-efficiency isolated bidirectional DC–DC converter for grid-connected energy storage applications. The converter forms an interface between a battery energy storage system (BESS) and a DC microgrid or inverter. First, the literature on bidirectional DC-DC converter topologies is collected, organised and analysed, including the non-isolated Buck/Boost, the isolated Dual Active Bridge (DAB), and the CLLC resonant converter. Second, the key working principles and advantages of each topology in energy storage applications are identified, followed by the selection and modelling of a suitable topology. Third, power stage components are designed based on specified system requirements, such as input voltage, output voltage, and power rating. In addition, modulation schemes for controlling the power flow are compared, and their impact on efficiency is analysed. Finally, the steady-state performance, dynamic performance, and efficiency of the simulated converter are evaluated and discussed.