Research Of Thermal Management Technology Of Electric Vehicle Power Battery System In Alpine Region

With the growing energy crisis and air pollution issues, research on electric vehicle technology has drawn increasing attention. As the main power of electric vehicle, lithium-ion battery is sensitive to the ambient temperature. Especially in low temperature, the capacity of lithium-ion battery will decrease sharply, the internal resistance of the battery will continue to increase, resulting in electric vehicle performance degradation. Under extreme low temperatures, electric vehicle can’t even be started directly, which greatly limits the population of electric vehicles in the northern Alpine region, this paper focuses on the study of low-temperature impact on the battery and considered the low temperature environment, a set of battery thermal managment is designed.Influence of low temperature on capacity, open-circuit voltage and the internal resistance of lithium-iron phosphate battery and Li(Ni Co Mn)O2 battery is studied by characteristics experiment. Pulse charging and discharging experiments is carried out to obtain equivalent heat capacity and heat transfer coefficient of the battery,which provides a theoretical basis of battery thermal management design.Secondly, based on the analysis of the warm-up mechanism of the battery, three warm-up modes are designed,and their advantages and disadvantages are compared. After analysis, heating the bottom of battery directly is an effective and feasible method to preheat the battery system. And then, the overall structural design of the power battery system is achieved.Finally, based on the clear requirements of the overall power battery system operating at low temperature, hardware and software design of a battery thermal management system are carried out. With completion of the thermal management system, a testing platform for power battery pack under low temperature is developed. And warm-up experiments of the battery pack are finished at different ambient temperatures, it turns out that the thermal management system can preheat the battery pack effectively, and enhance the performance of electric vehicles in the alpine region in cold environments.