A Hierarchical Energy Management Strategy of UFCEV

It is crucial to implement a precise control for autonomous driving programs of Unmanned Fuel Cell Electric Vehicles (UFCEV). To address the issue of energy utilization in UFCEV, a well-designed energy management strategy dealing with multiple energy sources is of great importance. In this paper, a hierarchical energy management strategy is proposed for fuel cell vehicle power system composed of fuel cell (FC), battery and supercapacitor (SC). The higher layer strategy controls the output state of the fuel cell through the power following strategy. In the lower layer strategy, a composite fuzzy strategy is proposed and improved by wavelet transform. The energy management of the battery and SC is realized by a wavelet-composite fuzzy strategy. The simulation results show that this hierarchical energy management strategy can maintain the average efficiency of the fuel cell at over 50%. At the same time, it can effectively employ the supercapacitor to bear the peak output load power, and ensure the power of battery and SC within the expected range, which will prolong the overall working life of the system.