Nonsolitary two-way DC-to-DC converters for hybrid battery and supercapacitor energy storage systems: A comprehensive survey

Abstract

Transport vehicles require an energy storage system (ESS) with a long lifespan to sustain their energy and power requirements during the start, acceleration, and recapturing of regenerative braking energy. However, a nonintegrated (i.e., single-use) ESS cannot satisfy the requirements of long lifespan, high energy, and power. Hence, a nonisolated direct current-to-direct current (DC-to-DC) bidirectional converter is widely used to integrate the battery and supercapacitor, thus meeting the requirements for vehicle starting, acceleration, and braking energy. Hybrid batteries and supercapacitor energy storage systems (HBSCESSs) are crucial because they preserve the battery lifespan. Supercapacitors handle the high transient currents and power requirements of these systems. However, the performance of HBSCESS depends on the converter configuration. There has been no comprehensive consolidated survey of nonisolated two-way DC-to-DC converters for possible HBSCESS development. It is imperative to compile this coherent analysis to help academia and industry select appropriate converter topologies for HBSCESS development, ideas, and guidance for new possible converters in transport vehicles, DC microgrids, and renewable energy source systems. This study provides an in-depth literature review and classification, assesses whether these converters provide a unified approach for HBSCESS development, and offers feasible solutions for future considerations. In addition, it provides recent research trends and recommendations for developing converters. This study analyzes the available literature on nonisolated converters for HBSCESS development. The analysis shows that multi-input, multi-port, three-port, coupled-inductor, switched-capacitor, and z-source/quasi-z-source converters are suitable for providing a unified hybrid energy storage system (HESS) comprising a battery and supercapacitor. They provide bidirectional power flow in both input ports for applications in transport vehicles, DC microgrids, and renewable energy source systems. The results also show that a single-inductor multi-input converter topology can be used for HBSCESS because it offers simple design, high efficiency, low component count, and moderate duty cycle operation.