Study On Energy Control Strategies Of Fuel Cell Hybrid Electric Vehicle

Recently, with the environmental pollution and energy crisis becoming seriously, energy-saving and environment-friendly vehicles have become the mainstream of development of automobile industry. The energy control of fuel cell vehicle has drawn more and more attention by many researchers. For the slow dynamic response of fuel cell system, the output character of the cell can not satisfy vehicles' requests during the start, acceleration and hill climbing. Therefore, a hybrid system is set up with an energy storage installment. In this paper, based on deeply analysis of native and foreign research results on fuel cell vehicle and the energy control strategies of the hybrid system, the latest research progresses and the existing problems in these results are summarized. The problem of the energy control strategy is explored systematically. The content is as follows:1. Firstly, the structures and characteristics of lots of fuel cells are comparatively analyzed. Secondly, based on the analysis results, the hybrid system which consists of proton exchange membrane fuel cell as the main source and super capacitance as energy storage system has been researched. Lastly, the structure, working principle and mathematical model of fuel cell and super capacitance are studied to construct the mathematical model of the hybrid system.2. The two energy sources of the hybrid system have been dealt with separately. Based on the constraints of the performance on fuel cell and super capacitance, the model of the system could be simplified, so the energy distribution problem could be converted into an optimal control problem about fuel cell system. Then a linear quadratic regulator with terminal time finite and constrained control signal has been designed. Simulation results verified the feasibility of the design.3. The hybrid power system has been taken as a whole, so the demanding current of the vehicle has been taken as an external uncertainty measurable disturbance to the system. The H(?) control theory has been used to design the energy control strategy. This thesis analyzes the stability of the closed-loop system without disturbance and the H(?) performance by defining a new Lyapunov-Krasovskii function. According to the performance analyzing, the H(?) controller has been designed. Simulations about different kinds of disturbances which may occur in vehicles have been done; results indicate that the H(?) control strategy is effective on restraining the disturbance and distributing energy.