High-Efficiency Partial Power Converter for Integration of Second-Life Battery Energy Storage Systems in DC Microgrids

This paper presents a power electronic interface for battery energy storage integration into a dc microgrid. It is based on a partial power converter employing a current-fed dc-dc topology. The paper provides an analysis of application requirements and proposes an optimal second-life battery stack configuration to leverage all the benefits of the partial power converter technology. This converter can regulate current at zero series voltage between a battery stack and a dc microgrid using the topology morphing control. The paper shows how the converter and its control system should be designed to operate in a droop-controlled dc microgrid. The experimental results demonstrate the converter's capability to operate under droop control, implementing both voltage step-up and -down regulation with a smooth transition between converter modes. The experimental efficiency reaches as high as 99.45%, demonstrating an efficient approach for battery energy storage integration into dc microgrid.