Research On Control Strategy For Thermal Management System Of Extended-Range Fuel Cell Electric Vehicles In Low Temperature

In response to the increasingly severe global environmental pollution and energy shortage issues,the Chinese government clearly proposed the major strategic goals of "Carbon Peak" and "Carbon Neutrality" in 2020,firmly adhering to the path of green and sustainable high-quality development.Accelerating the development of NEV(New Energy Vehicles)is an important measure to implement the national "dual carbon" strategy in the transportation sector.As a major component of NEV,fuel cell vehicles have become the focus of researchers due to their advantages of zero pollution,high efficiency,and long endurance,and have been considered as one of the most important development directions of NEV.Based on the major science and technology project "Development of Key Technologies for Fuel Cell Integration and Control" of Jilin Provincial Department of Science and Technology,this paper focuses on the research of extended-range fuel cell vehicles,aiming at the pain points such as high comprehensive energy consumption of their thermal management systems and low working efficiency in low-temperature environments.The research focuses on the structural design of thermal management systems and the development of low-temperature control algorithms,aiming to build a thermal management system architecture with its control strategy,which has wide environmental applicability,high energy utilization and ability to reduce vehicle power source life decay.In terms of system structure design,the parameter matching and optimization of vehicle powertrain have been completed,and an integrated thermal management system with waste heat recovery function has been designed;In terms of control algorithm development,a power source temperature trajectory optimization method based on PMP(Pontryagin minimum principle)was proposed,and a low-temperature thermal management control strategy based on fuzzy PID was designed.The results of the research show that the fuel cell vehicle thermal management system and its low-temperature control strategy constructed in this paper get a good performance in improving vehicle fuel economy.The specific research content of the paper is as follows:Firstly,starting with the powertrain configuration of fuel cell vehicles,the "fuel cell+power cell" powertrain architecture suitable for incremental fuel cell vehicles is selected.Complete the selection and parameter matching of powertrain components based on vehicle basic parameters and power economy requirements.The performance of the matched parameters was verified and optimized through simulation tests,providing a parameter basis for the subsequent design of the thermal management system.Secondly,the temperature characteristics of important components of the thermal management system are studied.Considering the temperature requirements of key assemblies such as fuel cells,batteries,and passenger compartments under operating conditions,an integrated design of the vehicle thermal management system was conducted,and a method for switching operating modes based on logical threshold values was developed.Establish an AMESim one-dimensional simulation platform to provide model support for the development of low-temperature control algorithms for the thermal management system.Thirdly,by combining theoretical research with physical experiments,a temperature model and a life decay model for a fuel cell-battery composite power source were established.On this basis,aiming at the optimization of the power source temperature trajectory in severe cold environments where heating energy consumption and power battery life decay is addressed,the temperature trajectory is solved based on the PMP minimum principle,and the optimal temperature trajectory of the power source heating process is obtained through offline simulation,providing data support for subsequent online control strategy development.Finally,based on the designed thermal management system structure and the optimized power source temperature trajectory,a control strategy is designed that comprehensively considered the passenger compartment temperature,power source temperature,and motor waste heat utilization in severe cold environments.Based on the structural design of the thermal management system and the developed control algorithm,the AMESim-Simulink joint simulation platform was established and the low-temperature control strategy simulation research of the thermal management system was conducted.The simulation results show that the application of the optimized power source temperature trajectory and its online control strategy can significantly shorten the heating time of the passenger compartment and significantly reduce the heating energy consumption during the vehicle low-temperature thermal management process.The comparative analysis of simulation results shows that compared to the linear temperature reference trajectory,the lowtemperature control strategy designed based on the optimal power source temperature trajectory can achieve a 7.3% reduction in PTC energy consumption,and a 2.8% reduction in the combined cost of battery power consumption and life loss.In summary,this article has designed a thermal management system architecture suitable for incremental fuel cell vehicles,proposed and validated a low-temperature thermal management control strategy for fuel cell vehicles based on composite power source temperature trajectory planning,which has reference value for promoting research on key technologies of thermal management for fuel cell vehicles and the application of product engineering technology.