Study On Characteristics And Control Of Fuel Cell Power System

Fuel cell power system is the power core of FCV.Its function is to convert the chemical energy of hydrogen fuel and oxidant into electric energy output,and drive the motor to provide power.The vehicle fuel cell type is usually the low temperature PEMFC,which has the advantages of high efficiency,fast start-up,low operating temperature,clean and environmental protection.The FC power system consists of stack and its auxiliary system.In order to make the FC power system work orderly,the characteristics of the system must be carefully analyzed and the management of the system must be reasonably controlled.Based on theoretical analysis,this paper makes an in-depth study of the fuel cell power system by means of simulation and experiment,and draws some conclusions about the system output characteristics,system dynamic characteristics and system control methods.Firstly,the working mechanism and structure of PEMFC are analyzed.A dynamic voltage model is presented to show the relationship between the fuel cell output performance and operating conditions.Through simulation analysis,the volt-ampere characteristic curves of fuel cells under different gas pressures,humidity and operating temperatures were obtained.The accuracy of the model and the correctness of the results were verified through performance tests.Finally,the output characteristics of the reactor were obtained.Then,for the air supply system,the model of air compressor,gas pipeline and back pressure valve is established by testing and measuring MAP,which can describe the change process of air flow and pressure.For the hydrogen supply system,the circulating gas supply structure is selected,and the models of pressure regulating valve,gas pipeline,hydrogen circulating pump and exhaust valve are established,which can describe the change process of hydrogen flow and pressure.For the thermal management system,the emphasis is on the heat balance analysis of the liquid cooling system,and the heat dissipation model and heat generation model are established,which can describe the temperature change process of the system.Next,in the MATLAB/Simulink simulation software,the steady-state and dynamic response characteristics of the fuel cell auxiliary system and the influence of the different working states of the auxiliary system on the system output performance were obtained through the simulation of the above mathematical model.The fuel cell power system test platform has been set up independently,and the rationality of the model and the correctness of the characteristic conclusion have been verified by completing relevant experiments.Finally,based on the existing research results of control methods,this paper innovatively proposed a coordinated control strategy.For different subsystems,the control methods of PID control,fuzzy control and predictive control are selected to simulate the system working state under the actual driving conditions of vehicles through simulation analysis,which verifies the rationality of the control method and enables the fuel cell power system to meet the output demand.In this paper,a technical platform for simulation verification and test of fuel cell power system is established,and a coordinated control strategy is developed.Through system simulation and test analysis,the response characteristics and output characteristics of the system as well as the practicability and effectiveness of the control are compared,so as to provide certain guidance for the integrated development of fuel cell power system.