| The active research and development of new energy vehicles,especially electric vehicles,have promoted the progress of technology for power battery.However,batteries,one of the crucial component for new energy vehicles,suffer heating problems from complex condition to impact on the thermal safety.Therefore,in order to avoid the heating problem affecting the normal use of batteries,it is necessary to take effective thermal management of measures after analyzing the thermal characteristics of batteries.The specific research are as following:1.The illustration for structure and heat generation mechanism of lithium-ion battery and the modeling for heat generation rate were established.Simultaneously,the thermal runaway process and influencing factors for different kinds of lithium-ion batteries were analyzed.The mathematical model of the temperature field for lithium-ion battery was established and the thermal property parameters were calculated.2.Firstly,the experiment for ambient temperature on discharging capacity and voltage gives a great priority to analyzing the heating behavior of the battery.Secondly,the internal resistance of batteries at different ambient temperatures and SOC was measured by HPPC method and polynomial fitting.Finally,the temperature rise of battery at different discharging rates from simulation compares with the experimental data,which verifies the accuracy of heating model.3.Construction of cooling plate was designed for heat dissipation analysis at 1C discharge rate.The purpose of the design of orthogonal experiment is to investigate the influences on coolant opening temperature,flow rate and coolant temperature on the heat dissipation by using the combination of single factor and multi-factor.Based on the result of orthogonal experiment,multi-objective optimization research was carried out,and the optimal heat dissipation effect was explored by taking the maximum temperature and temperature difference of battery as the comprehensive evaluation index.4.The temperature rise of battery pack at different constant speeds were experimentally investigated,and the internal heating condition was simulated.The comparison of the temperature curve collected in the battery pack with the simulation monitoring of the vehicle verified fully the reliability of the heat model.By continuing to explore the temperature rise of the battery pack at other speeds and establish the relationship between vehicle speed,maximum temperature of battery pack and driving time,which can provide guidance for temperature prediction of thermal management.5.Based on research for the optimization of heat dissipation performance with battery module,the liquid cooling plate was designed for the high-speed battery pack heating.And the liquid cooling performance was optimized by filling different types of thermal conductive glue in the internal gap of the battery.The results demonstrate that the liquid cooling heat dissipation structure and the gap filling thermal conductive glue can significantly reduce maximum temperature and improve the evenness of temperature distribution for battery pack.Based on the analysis of thermal characteristics for lithium-ion batteries under different discharge conditions,the liquid-cooled method was adopted to optimize the heat dissipation and liquid cooling of performance for lithium-ion batteries.The results of liquid cooling performance optimization will provide guidance for the development of battery thermal management strategy to further improve the thermal safety of electric vehicles. |
