Research On Dynamic Back Pressure Control Strategy Of Fuel Cell Power System Oriented To Optimal Electric Efficiency

With the thrive of fuel cell vehicle industry,fuel cell power systems as the core components of fuel cell vehicles are facing more and more challenges.One problem needed to be solved urgently is how to improve the electrical efficiency of the fuel cell power system.This thesis will study the optimization of the electrical efficiency,and particularly focus on the research on the dynamic back pressure control method aiming to achieve the optimal electrical efficiency.The research contents are as follows:1.This thesis carried out a qualitative and quantitative analysis on the electric efficiency evaluation index of a fuel cell power system,the influencing factors on the power generation efficiency of a fuel cell stack and the power consumption of auxiliary components of a fuel cell power system.Based on the analysis results,the fuel cell stack and its air system were selected as main research subjects.This is because stack is the core component,and its air system,which has the most factors affecting the efficiency of stack power generation,contributes the largest proportion of the power consumption of the overall auxiliary components of the system.2.With the understanding of the working mechanisms of the air compressor and fuel cell stack,models were built respectively for the two components based on the experimental performance data of the two components.The simulation analysis shows that models approximated to the actual operating situation of the compressor and stack.In addition,the electrical efficiency model for the fuel cell power system was established.The simulation results demonstrated that the electrical efficiency is related to the pressure and air flow of the stack cavity,and there existed an optimal system electrical efficiency under certain pressure and air flow of the stack cavity.3.This research optimizes the electrical efficiency of the fuel cell power system at each current density point based on the Particle Swarm Optimization(PSO),optimizes the pressure value and air flow value of the stack cavity of the power system,and compares the single optimization the air flow rate is used to optimize the electrical efficiency of the system.The system efficiency is increased by 6.786% on average,and the stack efficiency is increased by 7.671% on average.At the same time,the established electrical efficiency model is simplified for control,and the state space equation of the control object is obtained.The nonlinear controller is designed based on the nonlinear state space equation,and the effectiveness of the controller is proved by simulation.