Estimation Of State Of Charge And Internal Temperature Of Vehicular Mobile Energy Storage Lithium-Ion Battery

The gradual promotion of vehicular mobile energy storage cabins has improved the operating efficiency and flexibility of the power system.The lithium-ion batteries are usually used as the energy storage unit of vehicular mobile energy storage cabins,and usually used in tens of thousands of battery packs.Therefore,the safety and reliability of batteries have become the key to the energy storage battery management system,and the real-time acquisition of the battery charge state and temperature is an important basis for the energy storage battery management system to monitor and manage the battery state.Due to the limitations of traditional temperature measurement methods,only surface temperature of the battery can be obtained,and the actual situation of internal temperature cannot be identified,and the abnormal temperature cannot be warned in advance.Therefore,it is of great significance to study and explore the interrelationship between battery temperature and state of charge accurately estimating internal battery temperature,improve the accuracy of state of charge estimation,it has great significance for improving the level of battery management system and enhancing thermal safety performance.The main research contents of this paper are as follows:Firstly,select a suitable battery model according to the energy storage requirements,Then,the factors affecting the performance of lithium-ion batteries are investigated.Experimental schemes are designed based on the operational conditions and state estimation needs of the energy storage batteries.To set up a battery experimental platform.And analyze the characteristics of lithium-ion batteries based on experimental data to provide theoretical and data support for battery model construction.Secondly,considering the model complexity and accuracy comprehensively,a secondorder RC equivalent circuit model was selected to describe the electrical characteristics of lithium ion batteries,and the parameters of the equivalent circuit model for lithium ion batteries at different states of charge and temperature conditions were obtained using offline identification.Contrast the accuracy of the model by simulation and experiments.Moreover,to consider the time-varying parameters of temperature second RC equivalent circuit model,respectively using extended Kalman filter and unscented Kalman filter for lithium ion battery SOC estimation,reduce the error caused by the temperature difference,comparing the two algorithm estimation accuracy and robustness,optimizing the unscented Kalman filter as energy storage lithium-ion battery SOC estimation method.Finally,by analyzing the temperature field of the lithium-ion battery model,the single cell in the temperature concentration area in the battery module is selected as the research object.Through establishing a thermal model of the lithium-ion battery and using the EKF algorithm to estimate the internal temperature of the battery.Based on this,a thermal-electric coupling model considering the SOC and internal temperature of the battery is established to realize joint estimation of the SOC and internal temperature of the battery.The results show that the estimation method based on the thermal-electric coupling model improves the accuracy of both SOC and internal temperature estimation,and provides a certain reference significance for the estimation of SOC and internal temperature of energy storage lithium-ion batteries.