Modeling And Cooperative Control Of Vehicle Mounted Fuel Cell Supply System

Driven by the hydrogen energy policy and "carbon neutral" strategy,hydrogen fuel cell vehicles are developing rapidly,but the performance of hydrogen fuel cell vehicles needs to be improved in order to realize the full promotion and application of hydrogen fuel cell vehicles.The fuel cell supply system mainly provides sufficient hydrogen and oxygen for the fuel cell system,and maintains the stable pressure inside the fuel cell stack in the process.In order to improve the dynamic response performance of the fuel cell system and ensure that the fuel cell system can work safely,stably and efficiently,this paper conducts a control study on the fuel cell air system flow and pressure as well as the supply system cathode pressure difference-hydrogen stoichiometry ratio based on a certain80 k W high-power commercial vehicle,and the specific research work of this paper is as follows:Firstly,based on the working principle of the fuel cell,a fuel cell stack model including an anode gas flow module,a cathode gas flow module,a water transfer module,and an output voltage module is established,and the characteristics of the stack are analyzed to provide a theoretical analysis basis for the control study of the gas supply system.An experimental platform for the air supply system and hydrogen supply system is built,and tests are completed on hydrogen injector flow characteristics,sensor temperature and pressure calibration,air compressor flow characteristics,and air compressor surge line identification.Based on the experimental data and mathematical formulas,a semi-mechanistic and semi-empirical precise model of the gas supply system is established,providing data and model support for the control study of the gas supply system.Secondly,for the coupling problem of air system flow and pressure,this paper adopts two control algorithms,PID and fuzzy PID,to fine-tune the control of air inlet pressure,and on this basis,the non-decoupled flow-pressure cooperative control algorithm is developed to control the inlet flow and pressure of air supply system cooperatively.The results show that the non-decoupled flow-pressure cooperative control algorithm can achieve the fast stabilization of the system flow and pressure under dynamic variable load conditions and ensure the fast response of the system,and can control the steady-state error of the air inlet flow within 1g/s and the steady-state error of the air inlet pressure within1 k Pa,with good control effect.Finally,in response to the problem of large anode-cathode pressure difference in the gas supply system,this article uses a feedback linearization + PID control algorithm to control the anode-cathode pressure difference and hydrogen stoichiometric ratio based on the actual working requirements of the 80 k W fuel cell stack.The results show that the control algorithm adopted in this paper can quickly control the differential cathode pressure around the target value of 10 k Pa and the hydrogen stoichiometry ratio around the target value of 2 in dynamic variable load conditions,and the output voltage and power of the fuel cell system can quickly reach the steady state and maintain stability,meeting the fast response requirements of the system.In this paper,the dynamic response performance of the system is analyzed through a cooperative control study of the air system inlet stack flow and pressure and the cathode pressure difference of the supply system.The results show that the adopted control algorithm can meet the fast response requirements of the system.The research work in this paper can provide a reference for the flow and pressure control of the fuel cell supply system and for the improvement of the dynamic response performance of the fuel cell power system under continuous variable load conditions.