Energy Management Strategies for Hybrid Energy Storage Systems Based on Filter Control: Analysis and Comparison

The Filter-Based Method (FBM) is one of the most simple and effective approaches for energy management in hybrid energy storage systems (HESS) composed of batteries and supercapacitors (SC). The FBM has evolved from its conventional form in such a manner that more flexibility and functionalities have been added. A comparative study and analysis of the most recent and relevant proposals based on the FBM for HESS are provided in this paper. In this way, the improvements for this energy management system (EMS) are in the form of adaptive filters, rules, Fuzzy logic control, sharing coefficients, and additional control loops. It is shown how these enhancements seek to avoid the premature degradation of the storage devices that are caused by deep discharge, overcharge, and fast current variations in the case of batteries and overcharge in the SC case. Therefore, the enhancements are focused on keeping the battery and SC working within safe operational limits. This paper presents new comparisons regarding the SoC evolution in the storage devices, specifically how the SC SoC is used in the EMS to establish the power sharing. Numerical simulations are added to compare the performance of the different EMS structures. The analysis of the results shows the effectiveness of the FBM in achieving power allocation and how the latest proposed improvements help to add flexibility to HESS as well as to avoid premature degradation of the storage devices.