A Research of Different Energy Management Strategies of Lithium-ion Battery-Ultracapacitor Hybrid Energy Storage System

Abstract

Given the exacerbating effect of fossil fuel use in conventional vehicles on the greenhouse effect, the imperative development of electric vehicle technology becomes evident. To address the high energy and power density demands of electric vehicles, a lithium-ion battery-ultracapacitor hybrid energy storage system proves effective. This study, utilizing ADVISOR and Matlab/Simulink, employs an electric vehicle prototype for modeling and simulating both logic threshold and fuzzy logic control strategies. It aims to analyze the average output power and state of charge (SOC) of the lithium-ion battery, as well as the SOC of the ultracapacitor, within hybrid energy storage systems governed by these differing strategies. The findings indicate that the fuzzy logic control strategy results in a reduction of 2.73 kW in the average output power of the lithium-ion battery and a 20% increase in the SOC drop rate of the ultracapacitor compared to the logic threshold control strategy. Under the logic threshold control strategy, lithium-ion batteries demonstrate superior output stability, albeit within a broader amplitude range. Conversely, the fuzzy logic control strategy maximizes the utilization of ultracapacitors but leads to frequent fluctuations in the output power of lithium-ion batteries, thereby exhibiting reduced stability. These results underscore the inherent trade-offs between stability and utilization efficiency in hybrid energy storage systems for electric vehicles under different control strategies. The selection of a control strategy should be contingent upon specific performance priorities and objectives within the context of electric vehicle design and operation.