Modeling And Integrated Simulation Of Key Components Of Electric Vehicle Thermal Management System

The high fuel consumption and exhaust emissions of traditional internal combustion engine vehicles have exacerbated the global energy crisis and environmental pollution,which has caused the transportation industry to face severe energy and environmental problems.The development of energy-saving and environmentally friendly new energy vehicles with high energy utilization has become an effective solution.Electric vehicles are rapidly emerging in new energy vehicles with high efficiency,zero emissions and relatively mature technologies.Thermal management technology restricts the development of electric vehicles,especially the introduction of power batteries and changes in cabin heating methods,making thermal management research work of great value.This thesis focuses on the analysis of the thermal control capability of highpressure components,power batteries,heat pump air conditioning performance and the development of the vehicle thermal management and control strategy after system integration.Firstly,by analyzing the structure of electric vehicle thermal system and combining with the current research status of electric vehicle thermal management system,a heat pump thermal management scheme with motor waste heat recovery is proposed.According to the working principle and function of the key components in the thermal management system,the corresponding mathematical model was established based on the experimental data and the component characteristic data.According to the heat transfer mechanism of the heat,ignoring the influence of secondary factors,a heat conduction model of high-voltage components and power batteries was established.Considering solar radiation,temperature difference between inside and outside the vehicle and heat source inside the vehicle,an environmental load model inside the vehicle was established.Based on the key component model of the thermal management system,a high-pressure cooling system,a battery cooling system,an air circulation system and an air-conditioning system simulation platform were built.Through the simulation platform,the heat dissipation performance of the high-pressure system and the influence of the pump and fan working status on heat dissipation were analyzed separately;the temperature distribution in the cooling circuit of the battery active and passive liquid cooling;the cooling and heating load requirements in different environments in the vehicle;the air conditioning Cooling/heating capacity and coefficient of performance in different environment.Then,the driving force of the electric vehicle is analyzed,the relationship between the driving state of the vehicle and the power output of the motor is established,and the dynamic simulation model of the electric vehicle is built.Comprehensive analysis of the effect of electronic water pump and cooling fan on cooling system cooling,the control strategy of cooling fan is designed by using logical threshold method,and the control strategy of electronic water pump is designed by combining logical threshold method and proportional control method.The fuzzy adaptive PID algorithm is used to design the controller of the key control components of the air conditioning system,the compressor and the electronic expansion valve.According to the role and mutual influence of the control components in the system,the control strategies of other control components in the thermal management system are developed.Finally,the vehicle driving conditions are simulated by the electric vehicle dynamics model to calculate the heat generation rate of high-voltage components and power batteries;the controller outputs the control amount according to the operating state of the thermal management system;the thermal management simulation platform receives the heat generation rate of the dynamic model and The control system control quantity,and the system state quantity is fed back to the dynamic model and the control system in real time.Through the integrated simulation of the dynamic model,the control system and the thermal management system,the results show that the temperature of the high-pressure components and the temperature in the cabin have a better control effect.The combination of motor waste heat recovery and battery active and passive cooling is more conducive to battery energy saving.