Research On Matching Design And Thermal Management Control Of Proton Exchange Membrane Fuel Cell System

In order to conform to the global green and low-carbon development trend,under the background of carbon peak and carbon neutralization.Proton exchange membrane fuel cell(PEMFC)has attracted much attention because of its long service life,high energy conversion rate,low working temperature,fast start-up and other advantages.However,the output performance of fuel cell is affected by many factors.If the system parts are not matched correctly,the system cost will increase.At the same time,there may be problems such as insufficient fuel supply and high temperature when working conditions change,so as to reduce the output performance and service life of the system.At the same time,for performance and durability,thermal management is often regarded as an important influencing factor.A reasonable control method can not only improve the output performance of the system,but also improve the battery life.Therefore,in order to reduce the design and development cost of fuel cell system,improve the output performance and service life of the system,carry out reasonable matching calculation and selection of various auxiliary components,and study the thermal management control method with better control performance,which has important guiding significance for practical engineering application.Firstly,according to the theoretical analysis and the actual power demand of the system,this paper calculates and selects the key parts of the auxiliary equipment of the reactor,thermal management system,hydrogen supply system and air supply system.And then the fuel cell system platform is built according to the selection results.Secondly,for the sake of studying the influence of temperature on PEMFC,a dynamic model of stack is established based on its working principle.At the same time,in order to better study the control method,this paper establishes the fuel cell thermal management model based on the laws of thermodynamics and energy conservation.Through the comparative analysis of simulation and experiment,the effectiveness of the model is verified.Finally,according to the control requirements of PEMFC thermal management system,a sliding mode thermal management control method based on improved power reaching law is proposed.The improvements are as follows: in order to overcome the shortcomings of the traditional power reaching law,a piecewise function based on system state error is proposed to determine the reaching law coefficient;At the same time,considering the time delay of temperature and the discontinuity of symbolic function,the hyperbolic tangent function is used to replace the symbolic function.The results show that when the load and environmental parameters change,the maximum deviation of maintaining the inlet temperature of the stack is 0.03℃ and 0.024℃ respectively,the average regulation time is shortened by about 33 s,and the maximum overshoot is reduced by about 93%;Through experimental analysis,the average adjustment time is shortened by 17 s,and the maximum deviation is only 1℃.Therefore,the proposed control method has higher control accuracy and response speed,and has important engineering reference value.