Energy Management Strategy with Adaptive Cut-off Frequency for Hybrid Energy Storage System in Electric Vehicles

Abstract

The mixing of lithium-ion batteries (LIB) and Super-capacitors (SCs) is promising in the context of electric vehicles (EV) to minimize battery aging. This paper presents a power management strategy (EMS) based on the frequency method (i.e., low-pass filter) using an approach that allows adaptive cutoff frequency of the filter from the state of charge (SoC) of the SCs. In addition to the EMS, this study provides a dynamic model of the battery and SCs developed in Matlab/Simulink. Each of the two proposed models was evaluated separately before being merged into the model of the hybrid energy storage system (HESS). When the simulation results were compared to the test bench data, the suggested models were validated with an average inaccuracy of roughly 6% for the SCs and 3% for the battery model. Furthermore, the results highlighted the potential of frequency adaptation of the power management technique, which allows for better power distribution between the two sources. This latter adjusts itself based on the SoC of the SCs, thus improving battery’s lifetime.