Performance Analysis And Control Strategy Research Of Power Battery Integrated Thermal Management System

In order to address the issues of environmental pollution and energy shortage,new energy vehicles,represented by electric vehicles,have received widespread attention.As the main power source for electric vehicles,the performance,lifespan,and safety of power batteries are affected by temperature.Therefore,effective thermal management measures need to be taken for the battery system to maintain its temperature within the optimal working range.To address the problem of non-coordination and difficult centralized control of each subsystem in the split-type thermal management system of electric vehicles,this study designs an integrated thermal management system for power batteries,which effectively integrates the heat dissipation components of the system and studies its cooling performance.Based on this,an optimized control strategy is proposed.The main research work of this thesis is as follows:Firstly,the heat generation and dissipation characteristics of power batteries were analyzed,providing a theoretical basis for the experimental and simulation analysis of the thermal management system of power batteries.The integrated thermal management system architecture studied in this thesis was designed,and the flow and heat transfer characteristics of the refrigeration loop and cooling loop contained in the thermal management system architecture were analyzed to establish a mathematical model.Then,based on the designed thermal management system and heat sink structure,a 1:1power battery thermal management system test bench was built in a walk-in high and lowtemperature chamber.Different cooling modes and rule-based thermal management strategies were formulated based on the temperature rise performance of the battery system.The temperature rise of the battery system was tested under different testing conditions after implementing the thermal management strategies.The results showed that the thermal management system can effectively control the temperature rise of the battery system and keep it within a safe range,thus avoiding the occurrence of thermal safety issues.Subsequently,the temperature rise characteristics and thermal management energy consumption of the battery system under the rule-based control strategy for typical operating conditions are tested in this thesis.By analyzing the cooling performance and energy consumption of the thermal management system in the test results,the rule-based control strategy was optimized by adjusting the compressor speed,electronic water pump duty cycle,and electronic fan speed in the energy-consuming components of the thermal management system.The cooling performance and thermal management energy consumption of the optimized strategy were also tested.The experimental results showed that the thermal management energy consumption can be significantly reduced by reasonably reducing the compressor speed and electronic fan speed while ensuring the cooling performance.Compared with the original strategy at 25℃ and 40℃,the thermal management energy consumption for completing the comprehensive city working condition is reduced by 50.72%and 78.63% respectively,and the thermal management energy consumption for completing the high-speed working condition is reduced by 46.13% and 11.04% respectively.The optimal value of the flow rate of the electronic water pump exists,and the improvement of the cooling effect is more significant when the duty cycle of the water pump is 30%.Finally,based on the experimental research on the thermal management system,the performance of the thermal management system with the model predictive control strategy is simulated to reduce the fluctuation of the battery system temperature.The model of the integrated thermal management system for the power battery was built using AMESim,and a model predictive control strategy for the electronic water pump and the electronic fan was constructed in Matlab/Simulink for joint simulation analysis using AMESim/Simulink.The simulation results under urban comprehensive working conditions indicated that the model predictive control can stabilize the battery system’s temperature near the target temperature with small temperature fluctuations,effectively ensuring the safe operation of the battery system and improving its efficiency.Through experimental and simulation studies of the designed integrated thermal management system for power batteries and analysis of its performance and control strategy,the results of this thesis shown that the proposed integrated thermal management system and control strategy can effectively control the temperature rise of the battery system.The results of the study obtained can provide a reference for the integration and formulation of thermal management strategies for electric vehicle thermal management systems.