| This paper is mainly focused on the development and the design of flat-plate battery pack based on the pure electric car currently built in laboratory.By choosing 18650 lithium-ion power batteries,a systematic architecture of battery pack was built from the battery cell and battery module to the whole battery pack.Based on the framework and previous designing experience,the safety analysis and design of battery pack was established,plate-type structure of the pack was designed and package thermal characteristics was studied.The completed works are included as follows:(1)Safety analysis and design of battery pack:Under the pack system concept built,the components in the pack and the key techniques applied are analyzed,with an emphasis on electrical safety design and mechanical safety design of battery pack.And this part provides theoretical foundation and methodological guidance for the practical battery pack design through multiple perspectives,such as finite element simulation,vibration test and previous design experience.(2)Design of flat-plate battery pack:According to the four-wheel independently driving EV structure and vehicle dynamic requirements,the basic parameters of the pack were designed with 34 series-connected after 32 parallel-connected among the cells.And the structure designs of series-parallel connection and battery module were both conducted,considering the group elements fixation and insulation from the viewpoint of safety design in the process.Besides,the unique air-cooled cooling system components were also designed,which allows cells within the battery pack operate at a reasonable temperature range and achieve a balanced temperature distribution.The battery assembly was eventually designed to gain the specific energy of the whole pack as 100.33W·h/kg.(3)Thermal analysis of the battery pack cooling characteristics:In this part,the heating mechanism of lithium-ion battery was studied to establish heat and dissipation model in batteries.A two-dimensional thermal model of the cooling system was implemented on the basis of the internal resistance of battery properties and the structure of cooling system in order to study the cooling capacity of the battery pack under 1C discharge rate,and the designed cooling system requirements were verified by CFD analysis.Furthermore,air ducting structure was optimized to achieve the balanced temperature distribution,thus prolonging the service life of battery pack. |
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