Research On Simulation And Optimization Of Thermal Management Liquid Cooling System For Hybrid Electric Vehicle

The thermal management of Hybrid Electric Vehicle(HEV)is closely related to the power consumption,driving safety and riding comfort of the vehicle.The main goal of thermal management of HEV is to ensure that the temperature of the heating parts is controlled within the safe range,and further reduce the power consumption of the thermal management system.Compared with the fuel vehicle,HEV has more power components and different cooling fluid temperature requirements for different thermal management components,which also increases the design difficulty of the thermal management system of HEV.In this paper,the thermal management system of HEV was taken as the research object,and the heat generation and heat transfer of power components were analyzed.The independent vehicle thermal management system scheme were designed,and the important components of each independent thermal management subsystem were designed and calculated.A model was built for the designed independent thermal management scheme,and the model was experimentally verified.The model was used to simulate and analyze the independent thermal management scheme.Based on the simulation results,the original scheme was optimized.An integrated vehicle thermal management system scheme was proposed and a model was built.Finally,the temperature control performance and power consumption of the two vehicle thermal management systems were compared and analyzed.The main research contents are as follows:Firstly,the heat generation theory and heat transfer theory of battery pack,engine and other components of hybrid electric vehicle were studied,and the heat transfer mechanism of vehicle thermal management was analyzed,which provides a theoretical basis for the design and modeling of thermal management scheme.Secondly,according to the relevant structural parameters and power component parameters of a hybrid electric vehicle,the power system of the hybrid electric vehicle was modeled by GT-SUITE software.The heat generation power of the battery pack,engine and motor under typical working conditions were studied。The maximum heat generation load of each power component of the target vehicle were determined,which provides a basis for the parameter design of the vehicle thermal management system.Thirdly,the scheme and model of the independent vehicle thermal management system for HEV were designed and built,and the model was verified by experiments.The results show that the relative error between the simulation results and the experimental results is less than 10% for the verification of the battery heating temperature and the coolant parameters of the thermal management system.The model can be used for the simulation analysis of the performance of the thermal management system.Based on the thermal management model and heat generation load,the main components of the thermal management system were designed and matched,and the design and calculation process of heat exchanger in each system were emphatically expounded.Finally,the influence of environmental temperature,initial SOC of battery pack and vehicle speed on temperature control of independent vehicle thermal management system were analyzed.The results show that the temperature rise rate of the battery pack and the motor coolant outlet in the independent vehicle thermal management system are slow at low environmental temperature.The initial SOC of different battery packs has an impact on the working mode of HEV.The heat generation of thermal management components are different,which makes the temperature control effect of thermal management system different.The thermal management system can control the outlet temperature of battery pack,engine and motor coolant at low,medium and high speed.Based on the simulation results,the independent vehicle thermal management system model was optimized,the integrated vehicle thermal management scheme was proposed,and the corresponding thermal management system model was established.The temperature control performance and power consumption of the two thermal management systems under NEDC(New European Driving Cycle)conditions were compared and analyzed.The results show that the integrated vehicle thermal management system is superior to the independent vehicle thermal management system in terms of temperature control performance and power consumption.