| Unprecedented opportunities for development of pure electric vehicle industry have been brought by constantly growing problems of energy crisis and environmental pollution. The performance of electric vehicles is decisively influenced by battery pack, which is the only power source of pure electric vehicles. However, the efficiency of battery will be reduced by ultra-high, ultra-low, or uneven temperature distribution inside the battery pack. Therefore, Effective thermal management of battery pack is essential for electric vehicle to adapt to different kinds of external environment, achieve desired working efficiency and life cycle of the power batteries.Taking18650lithium-ion battery in a kind of domestic pure electric vehicle as example, the methods of theoretical analysis, numerical simulation and actual experiment have been adapted to researching thermal characteristics of single cell and battery pack. In this paper, a novel thermal management system is designed, and simulation analysis of the thermal management system will be carried out to optimize the structure parameters of battery pack. The main contents are as follows:Firstly, structure and heat mechanism of lithium-ion battery is learned after a review of related literature. And the working performance of batteries under different temperatures will be analyzed in order to determine the design goal of thermal management system.Secondly, three-dimensional CFD simulation and actual experiment are taken to research temperature rise of a single cell under different discharge rate. Temperature rise of lithium-ion battery in the discharge process under natural cooling conditions will be assessed. Also, the accuracy of the single cell simulation model and related thermal parameters can be verified to support the further research.Thirdly, simulation model of the designed battery pack will be built and reasonable simplifying should be conducted. Parameters of key components can be achieved to decide different boundary conditions needed in the follow simulation work. The heating and cooling element inside the thermal management system is equivalently simplified, and simulation combined with actual experiments will be done in order to validate the effectiveness of the established equivalent model.Finally, flow and temperature distribution inside battery pack under different working conditions is achieved by simulation, and several optimization programs will be presented based to the deficiency of simulation results. The final scheme is decided upon the optimization results which can be effective to ensure an appropriate temperature range and the normal work of the power batteries in electric vehicle. |
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