Modeling And Temperature Control Strategy Of Air-Cooled Proton Exchange Membrane Fuel Cell Thermal Management System

Fuel cell is considered as a subversive technology,which directly converts the chemical energy stored in hydrogen into electrical energy through electrochemical reaction.Proton exchange membrane fuel cell（PEMFC）has attracted much attention and favor in the field of in-use power generation because of its advantages of high efficiency,low noise,zero-emission,and high energy density.Air-cooled PEMFC integrates oxygen supply system with the cooling system Compared with water-cooled PEMFC,aircooled PEMFC does not require peripheral humidification equipment,so it has a more streamlined system structure and has good application prospects in the fields of small backup power and drones.However,the air-cooled PEMFC system has problems such as few controllable variables,high coupling of hydrothermal management and difficulty in precise temperature control,resulting in its low reliability and stability in the actual operation process,which hinders its large-scale commercialization process.A good thermal management system and precise temperature regulation have important theoretical and practical significance for improving the performance of fuel cells,prolonging their life,and accelerating their commercialization.Therefore,this paper will focuses on the following researches on the thermal management system and temperature control strategy of air-cooled PEMFC:Firstly,the working characteristics of the air-cooled PEMFC thermal management system and the temperature characteristics of the fuel cell are explored through experiments.Based on the research on the working characteristics of the axial fan,the study on the fan speed,working area and working mode will provide strong support for the subsequent fan control.A temperature characteristic experiment is designed,and the corresponding relationship between the optimal operating temperature of the fuel cell and the load current is obtained based on the experimental results.Finally,the thermal imaging technology is used to explore the distribution and evolution of the internal temperature of the fuel cell,which provides theoretical and experimental data support for the thermal management system modeling and temperature control strategy design.Then,based on the experimental data of temperature characteristics and the reaction mechanism of the air-cooled fuel cell,a dynamic model of the thermal management system of the proton exchange membrane fuel cell is constructed,which consists of an output voltage model and a temperature model.The temperature dynamic response experiment is designed on the air-cooled fuel cell test platform to verify the model.The average error of the obtained output voltage is 0.1V,and the average error of the output temperature is 0.0126℃.The results show that the proposed output voltage model and temperature model can effectively predict the output voltage and temperature of the stack,and provide a model basis for the research of temperature control strategy.Finally,an optimal temperature control strategy for the air-cooled fuel cell is proposed to optimize its output performance.Based on the dynamic model of the thermal management system of the air-cooled fuel cell and the relationship between the load current and the optimum temperature,the active disturbance rejection and model predictive controllers are designed respectively.The controller simulation model is built in Simulink,and experiments are used to verify the control effect of the controller.The results show that both controllers can make the fuel cell operating temperature approach the target temperature quickly and smoothly,and the model predictive controller has less overshoot and shorter transition time than the ADRC.