Research On Key Components Design And Thermal Management Strategy Of Liquid Cooled Battery Thermal Management System

The development of new energy vehicles is an important measure to solve the oil crisis and environmental problems.As the main energy source of new energy vehicles,power batteries are the core components of automobiles.Lithium-ion batteries have high energy density,high voltage,low self-discharge rate,and good stability.The advantage is the first choice for new energy vehicles.Lithium batteries are sensitive to temperature.The power battery produces heat during the working process.If the heat cannot be dissipated in time,the battery temperature will rise.Excessive temperature will easily cause thermal runaway and lead to safety problems.Too low temperature makes it difficult to charge the battery.The capacity is reduced,and the temperature difference of the lithium battery is too large,and the life of the battery pack will drop rapidly.In order to ensure the safety of power battery operation and extend the cycle life,it is necessary to carry out related research on battery thermal management system.This article takes liquid-cooled battery thermal management system as the research object:(1)Establish a single battery heat generation simulation model;taking the Ningde era 50 Ah square ternary lithium-ion battery as the research object,according to the relevant parameters of the battery,the required physical parameters are calculated through theory,the DC internal resistance of the battery is obtained by the experiment,and the difference in the battery is calculated.For the heat generation power under the discharge rate,a single lithium battery heat generation simulation model was established.The experiment obtained the comparison of the average temperature rise of the battery and the simulated temperature rise under different discharge rates,and verified the accuracy of the simulation model.(2)A liquid-cooled plate is designed for the power battery module;the design goal of the liquid-cooled plate is determined according to the thermal characteristics of the battery.A battery module composed of 48 single lithium batteries is used as the research object.Through the simulation of the single battery,Confirm the location of the liquid cooling plate,design three kinds of flow channel structures,select the flow channel structure with good temperature uniformity according to the evaluation index,and then simulate and analyze the influence of the flow channel length on the heat transfer performance,and select the larger flow channel length.Finally,the inlet size of the liquid-cooled plate runner is optimized.(3)The influence of different parameters on the maximum temperature and temperature difference of the battery is simulated;the designed liquid-cooled battery module heat exchange structure is taken as the research object,and the inlet flow in different environments(transient)is simulated and analyzed under steady state and transient state.,The influence of inlet temperature and discharge rate on the maximum temperature of the battery and the influence of temperature difference,summarize the rules,and provide a reference for the designation of thermal management strategies.(4)The thermal management strategy was determined,and the feasibility of the strategy was verified through simulation;on the basis of the Changan Yidong EV pure electric vehicle,the vehicle power system,thermal management system and control model were built using Amesim,and the battery temperature was divided into different temperature zones.Different thermal management strategies are adopted in the area,and the battery temperature rise is simulated under different cycle conditions and ambient temperatures.The battery temperature is controllable and within a reasonable temperature range,which verifies the rationality of the thermal management strategy.(5)A strategy to reduce the probability of thermal runaway is proposed;the mechanism of thermal runaway is analyzed,the intelligent secondary battery pack is added to the existing battery thermal management system,and the design and selection suggestions for secondary battery and cooling system related components are proposed.