Research On Heating Method Of Lithium Battery Under Low Temperature Environment

Environmental pollution and the energy crisis have promoted the development of new energy sources.In recent years,lithium-ion power batteries have been widely used in the field of civil aviation with excellent performance.At present,lithium-ion power batteries will inevitably be in a low temperature environment when applied to the aviation field,and the performance of lithium-ion batteries in low temperature environments will be greatly reduced.Therefore,it is important to improve a low-temperature preheating technology for batteries.This thesis mainly focuses on the low-temperature preheating of 18650 lithium-ion battery.Firstly,the temperature characteristics of lithium-ion batteries were studied in a low temperature environment of-20℃.Based on the increase of internal resistance at low temperature,an AC heating circuit is designed.AC preheating combined with external preheating of electric heating film.This method can reduce the temperature gradient of lithium battery in the heating process.In the next step,the temperature control program is written through professional software.Then the lithium-ion battery preheating platform is built,and many experiments and analysis are carried out.In the heating process,the pulse width modulation frequency is also analyzed in detail,and the optimal heating frequency for heating lithium-ion battery in this thesis is obtained.Through the heating experiments of lithium battery under different charging States,it is verified that the composite heating technology can still preheat the battery under different residual power.Finally,combined with the dual Kalman filter algorithm developed by professional software,the remaining useful life of battery is analyzed.Based on the discharge data from the charge and discharge experiment of heated lithium battery,the parameters of the second-order RC model are identified by the least square method.The remaining life of the battery is effectively predicted by DEKF.The prediction results show that the composite heating technology will not cause excessive life consumption for lithium-ion battery.It is proved that the improved battery preheating technology has certain practicability.