Study On Lithium Ion Power Battery Liquid Cooling System For Battery Electric Buses

In this paper,the power battery system of battery electric bus is studied,and the research work of the power battery liquid cooling system is focused.This paper introduces the research background and significance of lithium ion power battery cooling system,summarizes the research status and application status of lithium ion power battery at home and abroad,the liquid cooling method is the development direction of power battery thermal management.This paper analyzes the working principle,heat and heat transfer mechanism of lithium ion battery,conducts the power battery experiment,analyzes the effect of temperature on battery charge and discharge through the experimental study of a 50 Ah phosphate lithium battery.The conclusion is that when the high-rate discharge of the battery in high temperature environment,the heat of the battery is large and the temperature rise quickly.The liquid cooling of power battery is the hot spot and development trend of the research,and the basic principle of liquid cooling system is analyzed.Through the theoretical calculation and establishment model,the simulation analysis of the temperature field distribution inside the battery pack by the fluent software,the simulation results show that the whole design of the battery pack and cooling system is reasonable.Based on the results of theoretical study,the overall design of the cooling system and the internal structure of the power battery pack is designed,and the liquid cooling power battery system is designed.This paper analyzes the power demand data of typical cities in China and the actual operation conditions of vehicle,determines the charge and discharge experimental rates of power battery,establishes the switching control conditions of liquid cooling single compressor and double compressor,designs and builds the test bed of liquid cooling power battery system,and carries out the bench experiment of liquid cooling power battery system.The designed liquid cooling power battery system is integrated into the whole vehicle,and the vehicle rapid charging condition experiment and comprehensive road reliability experiment,bench experiment and vehicle experiment are combined.The experimental results verify that the designed liquid cooling power battery system and its control strategy meet the requirements of the vehicle,and verify the simulation results of the liquid cooling system power battery.