Review of structures and control of battery-supercapacitor hybrid energy storage system for electric vehicles

The energy storage system (ESS) is the heart of electric vehicles, which determines their efficiency, power, and driving range, etc. The emerging demand of modern electric vehicles often requires the ESS to preserve high energy density, along with the high peak power. Nowadays, batteries and supercapacitors, which could deliver high energy and power capability respectively, are commonly used as the ESS in industrial practice. A hybridization of them, the hybrid energy storage system (HESS), will potentially take their individual advantages, thus supplying a large burst of current and also storing enough energy to ensure a sufficiently long driving range. This paper reviews the state-of-the-art technology for batteries, supercapacitors, and the HESS. Various structures and topologies for the HESS are discussed, and control strategies are investigated.