Modeling And Optimization Of Fuel Cell Vehicle Thermal Management System

The global environmental situation is becoming more and more severe,and the diversification of energy structure and environmental protection are becoming the trend of development.Hydrogen fuel has attracted widespread attention of the human society due to its cleanness,safety,and high efficiency.Vehicles equipped with hydrogen fuel cells are more than existing new energy vehicles.It has the advantages of short fuel supply time and long cruising range,which will become the development direction of new energy vehicles in the future.However,there are still technical barriers to the development of fuel cell vehicles,such as thermal management issues under complex operating conditions.This thesis takes a certain fuel cell vehicle as the research object,and comprehensively considers the vehicle layout environment and thermal management requirements,and designs a complete thermal management system for hydrogen fuel cell vehicles.Build a relatively complete vehicle-level fuel cell vehicle thermal management system model,and use the co-simulation method to analyze the temperature control performance and energy control performance under complex working conditions for different vehicle thermal management control strategies,and optimize the control performance.A strategic approach to improve vehicle thermal management performance.It can provide some ideas for the development and research of the thermal management system of the fuel cell vehicle in the future.The main research work can be summarized into the following 4 aspects:(1)Design of thermal management scheme for fuel cell vehicles.Based on the space layout environment and thermal management requirements of the vehicle,the architecture scheme of the vehicle thermal management system is clarified from the two design perspectives of structure and principle;the thermal load analysis and demand calculation of the thermal management system are carried out from the two aspects of heat generation mechanism and heat dissipation method.The selection and performance matching design of key components such as radiators and water pumps are completed accordingly.(2)The simulation model of the thermal management system of the fuel cell vehicle is built.Based on the AMESim platform,the vehicle power system modeling was completed,and the vehicle dynamics were verified through the tests of the new European driving cycle NEDC and the Chinese passenger car driving cycle CLTC-P.Four thermal management distributed subsystems of fuel cell,power battery,electric drive and air compressor are integrated,and the power system model is integrated to establish a one-dimensional simulation AMESim model of vehicle-level fuel cell vehicle thermal management,and the model is verified by experimental data.After verification,the relative errors are controlled within 5%,showing that the model has high computational accuracy.(3)Exploration on the operation performance and influence rules of the thermal management system of the fuel cell vehicle.Taking the system energy consumption,the inlet and outlet water temperatures and temperature differences of components as evaluation indicators,the steady-state and transient conditions of the system were simulated to investigate its thermal management performance under multiple conditions;the single-variable control method was used to explore different environments.Influence law of thermal characteristics of model parameters such as temperature,coolant flow rate,and cooling wind speed.The study shows that the influence of ambient temperature on the heat dissipation performance decreases with the increase of the load;simply increasing the cooling liquid flow has limitations in improving the thermal management performance;increasing the cooling air flow can significantly improve the system heat dissipation performance;the PTC opening temperature is set to 10 ℃,It has the least heating power consumption and the best cold start comprehensive performance.(4)Formulate and optimize the control strategy of the vehicle thermal management system.To ensure the safe temperature of the system,reduce the temperature fluctuation,and reduce the energy loss of the system,four control strategies,namely logic control,PID control,fuzzy control and fuzzy adaptive PI control,are formulated,and the control model is built based on the Simulink platform;Integrate the control strategy Simulink model and the thermal management system AMESim model to establish a co-simulation model of the vehicle thermal management system;take the logic control scheme as a reference,carry out a comparative analysis of the thermal management and control performance of the control strategy based on the cosimulation model,and obtain a fuzzy adaptive PI control strategy The comprehensive control performance is the best.This solution can save system energy consumption by37.88%,which can well meet the cooling requirements of the whole vehicle,stably control the temperature of components,and realize the coordinated optimization of the energy consumption of the thermal management system.