| With the development of new energy vehicles, power battery pack, served as an important energy storage component and power source of electric vehicles, has become the focus of the research around the world. Lithium-ion batteries have many advantages such as high storage energy, high energy density, long service life and high voltage withstanding, which can meet the requirements of vehicle power battery. Thus, they are widely used in electric vehicles. The safety of lithium-ion battery pack includes many aspects. Thermal safety is one of an important part. The operating temperature of Lithium-ion battery pack is essential for the safety of power battery and even electric vehicles. Working long hours in poorly thermal condition will significantly affect the functions of power battery, even bringing unrecoverable damage. Therefore, it is needed to design reasonable structures of power battery pack to control high the battery pack temperature in the range of reasonable.First of all, this project builds up the thermal effect model of battery cell through deeply analyzing the heating mechanism of lithium-ion battery and obtaining accurate heat generation rate of lithium ion battery by combining the theoretical and experimental research. It is divided into several parts. Firstly, carry out cell characteristics experiments and constant charge-discharge rate experiments according to the battery test manual. Then, obtain the resistance characteristics and open circuit voltage characteristics by characteristics experiments, and take out the method to calculate heat rate of battery cell. Finally, analyze the temperature rise of the lithium-ion cell under the constant charge-discharge rate experiments, with which verify the accuracy and validity of the heat generation model of the battery cell.Build the three-dimension heat generation model of lithium-ion battery pack bases on the heat generation model of lithium-ion battery cells. In the case of natural wind cooling, through steady simulation, analyze the influence of cells number of battery modules, the number of air inlet and outlet of the battery pack and the shape of the battery pack inlet and outlet on temperature field of battery pack. In the case of forced air cooling, analyze temperature field of battery pack through steady simulation. And analyze the effects of inlet air velocity on the heat dissipation structure of the battery pack under different charging and discharging rates.In order to improve the uniformity of temperature distribution of the lithium-ion battery pack, the paper study on the temperature field of battery pack when air inlet and air outlet are put on the side of battery pack. Based on the results of these studies, improve cooling structure of battery pack. Finally, heat dissipation and temperature uniformity of the battery pack are improved. |
PDF Full Text Request