Overview of Supercapacitor Management Techniques in Electrified Vehicle Applications

Ultracapacitors (UCs) have been recognized as an enabling technology for electrified vehicles (EV) applications. They have high power density, low internal resistance, wide operating temperature range and excellent recyclability. These desirable merits render them well-suited to work independently or in combination with high-energy devices for peak power handling under practical driving conditions. A capable UC management system is necessary for ensuring safe, efficient and reliable of UC systems. This paper presents a comprehensive overview of UC management techniques, with the primary goal to summarize recent progress and spark innovative ideas for further research advance. The state-of-the-art control-oriented modeling, state estimation and balancing management techniques are systematically surveyed. Especially, state-of-charge (SOC) estimation and state-of-health (SOH) monitoring are covered, with detailed analysis on the underlying aging mechanism and influencing factors. Balancing techniques, which are critical for enhancing system efficiency and preserving UC service life, are explicated. For EV applications, diverse configurations of battery-UC hybrid energy storage system are examined, and the associated energy management strategies are reviewed. The independent utilization scenarios of UC systems are also exhibited. Finally, the prospects for UC management technique development and applications are discussed.