A Novel DC Transformer (DCX) for Single-Phase Battery Energy Storage System and Current Ripple Suppression Strategy

A high performance bidirectional dc transformer (DCX) is proposed in this paper for connecting energy storage battery and grid-connected inverter. The proposed DCX can not only realize charging and discharging of energy storage battery, but also effectively suppress the high-frequency and low-frequency current ripple in the battery-end. Besides, the LLC resonant tank in the DCX ensures that soft-switching can be achieved for power devices—zero-voltage-switching (ZVS) for power switches and zero-current-switching (ZCS) for rectifier diodes. The proposed DCX shows high performance in efficiency and electromagnetic interference (EMI). The effectiveness of the proposed converter and current ripple suppression strategy are verified by experimental results.