Optimal fuzzy logic based energy management strategy of battery/supercapacitor hybrid energy storage system for electric vehicles

The main purpose of this paper is to describe a novel power management control strategy for battery and supercapacitor hybrid energy storage system with the objective that the load power demand would be distributed into the energy storage devices in a way that each device can be utilized optimally. The paper describes the design and control of such an on-board hybrid energy storage system. The specific control strategy is designed based on a fuzzy-logic controller (FLC), which offers the advantage of flexibility and robustness and has been widely applied to the energy management or power distribution of multiple power sources system of an electric vehicle, to avoid the low efficiency operation region of every power source and achieve high efficiency without degrading the mechanism performance. However, prior experience fuzzy logic supervisory control is often difficulty in realizing the optimal distribution between battery and supercapacitor. In the presented research, an optimization method based on gold ratio cut-off rule is proposed to design the degree of hybridization (DOH) and membership functions of the fuzzy controller, to realize the optimal performance of fuzzy logic controller. The proposed optimization method is simple and effective, and can be applied to the practical hybrid system directly. Finally, the effectiveness of the proposed method was examined by using ADVISOR simulation platform, and in which the hybrid energy storage system was developed and embedded into the electric vehicle model. The model parameters were gained from the tested vehicle. Simulation results have shown that the proposed method can efficiently distribute the power between battery and supercapacitor to realize the design objective set forth.