Hybrid Energy Storage System with Power Surge Capabilities Utilizing Six-Port Converter for Cell Management

A hybrid energy storage architecture that consists of energy storage string of cells, typically lithium batteries, and power surge capable string of cells, typically supercapacitors is presented. The major challenge – cells management in a multi string multi cell system is tackled in this work by introducing a novel six-port converter, which on one hand enables to balance individual cells across each of the strings, while on the other hand provides a low power means of shuttling the charge between the strings as necessary. The unique converter topology uses capacitive coupling between the cells on the same string, and near unity conversion ratio isolated transformer coupling between the energy and power strings, providing single conversion high efficiency balancing operation and cutting significantly on the number of required components. A simulation and experimental validation of the converter operation and hybrid energy architecture functionality is carried out on a laboratory prototype, and a good agreement is found between the theoretical analysis and experimental results.