A Novel Hybrid Energy Storage System With an Adaptive Digital Filter-Based Energy Management Strategy for Electric Vehicles

This study aims to develop a novel hybrid energy storage system (HESS) with an adaptive digital filter-based energy management strategy (ADFBEMS) for electric vehicles (EVs). The proposed HESS comprises a lithium-ion (Li-ion) supercapacitor (SC) and a battery module. An interleaved boost converter with synchronous rectification, which can achieve the load power distribution function, connects the SC with the battery module. Furthermore, the proposed ADFBEMS utilizes the sliding discrete fast Fourier transform (SDFFT) to track the instant load spectrum and the low-pass filter with the adaptive cutoff frequency to realize the load distribution based on frequency, where the SCs take charge of the load's high-frequency component, and the battery module supplies the rest of the load component. A model of the proposed HESS with ADFBEMS is developed in MATLAB and verified through the hardware experiments under the worldwide harmonized light vehicles test cycle (WLTC) Class 1. Both the simulation and hardware experimental results prove the proposed HESS with ADFBEMS's effectiveness by comparing it with the traditional filter-based (fixed cutoff frequency) energy management strategy (EMS). With the help of the proposed HESS with ADFBEMS, Delta P-stress and the high-frequency ratio (HFR) can be reduced by 11.06% and 27.46%, respectively, which was beneficial to the battery module's lifetime.