Research On Modeling And Control Of Water-cooled PEMFC Cooling System

Addressing energy crisis and environmental pollution caused by fossil-fuel energy usage has promoted the development of clean,sustainable energy and Hydrogen energy has been one of ideal solutions for future energy problem.Proton Exchange Membrane Fuel Cell(PEMFC),as one of the most popular in hydrogen energy research filed,has many advantages such as pollution-free,high energy density,high energy conversion efficiency,and good environmental adaptability.It has been widely used in hybrid vehicles,mobile portable devices,unmanned aerial vehicles and other fields.Temperature is a key parameter affecting the output performance of PEMFC system.The thermal management can maintain the stability of temperature under steady and dynamic load state,improve the performance of PEMFC and extend the life span.Therefore,it is very meaningful to study the thermal management system of the water-cooled PEMFC.In the article,the electrochemical characteristics of the PEMFC,the flow and pressure characteristics of the mixed gas in the cathode and anode flow fields,the water transport characteristics in the PEM and the heat transfer characteristics of stack and the components of the cooling system loop are considered.Based on the electrochemical reaction principle,the thermodynamic principle and the law of mass conservation,the semi-empirical model of the stack and the dynamic model of the thermal management system are established.The model is verified by comparing the simulation and experimental data.In order to study the effect of cooling system operating parameters on system heat dissipation,based on the established PEMFC cooling system model,the coolant temperature at inlet and outlet and the temperature difference between inlet and outlet are regarded as the index parameters to evaluate the heat dissipation performance and the bypass valve opening,coolant flow and air flow in the cooling system are regarded as the operating variables for the study of heat dissipation performance.The influence of each single operating parameters on every heat dissipation performance index parameters is studied.The operating parameter sensitivity of each heat dissipation performance index parameter is analyzed through orthogonal experiment method.The control requirements of PEMFC cooling system are proposed.The strong coupling characteristic of cooling system is analyzed.To deal with coupling in cooling system,a dynamic decoupling and control strategy based on linear active disturbance rejection control is proposed for cooling system with coupling.To control temperature stack system collaboratively,LADRC is designed for the coolant flow and air flow control loop.Then,the ADRC controller parameters in the two control loops are determined by combining the trial and error method with simulation analysis.Simulation experiments are carried out under current disturbance and membrane water content disturbance respectively and the control effects are analyzed.The results show that the stack temperature and the coolant temperature difference can be stabilized at 343 K and 7 K,the maximum deviation less than 0.8 K,and the overshoots are 0.23%,11.14% and 0.05%,2.85% in two cases respectively.It’s reveal that the control strategy proposed in thesis can meet the control requirements.