Integrated Supercapacitor Cell Balancing and Multi - Parameter State of Health Estimation for Hydrogen Fuel Cell Electric Vehicles

Hydrogen Fuel Cell Electric Vehicles (HFCEVs) require efficient energy storage systems to manage transient power demands and improve overall powertrain performance. Supercapacitors are suitable for this purpose because of their high-power density, rapid charge–discharge capability, and long cycle life. However, series-connected supercapacitor cells can experience voltage imbalance due to variations in capacitance, leakage current, temperature, and ageing. In addition to voltage balancing, estimating the State of Health (SOH) of supercapacitors is essential for assessing degradation and maintaining reliable operation. This paper presents a proposed integrated supercapacitor cell balancing and multi-parameter SOH estimation system for HFCEV applications. The system incorporates a BW6101-based balancing circuit and evaluates supercapacitor health using five parameters: cell voltage, Equivalent Series Resistance (ESR), capacitance, leakage current, and temperature. Capacitance retention and ESR variation serve as primary degradation indicators, while voltage, leakage current, and temperature provide supplementary information about cell operating conditions. The acquired parameters are intended to support health assessment through a defined estimation method, with the potential for digital monitoring and remote data visualization. The system is designed to combine cell-voltage balancing with condition assessment, thereby supporting the identification of voltage deviations and possible supercapacitor degradation. Experimental evaluation will focus on balancing performance, parameter measurement, and SOH estimation accuracy. The proposed approach provides a foundation for developing an integrated supercapacitor management system for automotive energy storage applications.