SOC Estimation Of Li-ion Battery Pack

With the development of Li-ion battery technology, Li-ion battery applied to energy storage system has become more and more general. Li-ion battery SOC estimation is an important part of Li-ion battery pack management system, which provides protection for the security and long-term use of Li-ion battery. Based on Li-ion battery storage technology, this article studies the fundamental characteristics, SOC estimation methods and estimation correction of Li-ion battery.In the basic performance of Li-ion battery, this paper introduces the basic principle of Li-ion battery, the capacity characteristics, battery internal resistance and the open circuit voltage of Li-ion battery. The capacity characteristics of Li-ion battery study on the effect of discharge rate, temperature and discharge cut-off voltage. Li-ion battery internal resistance characteristics study on the effect of SOC and environment temperature. The open circuit voltage characteristics study on the effect of SOC and environment temperature.In the Li-ion battery SOC estimation methods, this paper discusses the Li-ion battery equivalent circuit model, the extended Kalman filter and using extended Kalman filter based on PNGV model to estimate Li-on battery SOC. Li-ion equivalent model studies on PNGV model, multiple linear regression and using multiple linear regression to identity the parameters of PNGV model. The extended Kalman filter study on the principle of extended Kalman filter and the working process of extended Kalman fiter applied into PNGV model. To verify the Li-ion battery SOC estimation method, the relevant experiment is performed.In the Li-ion battery SOC estimation correction, this paper proposes the SOC initialization correction, the SOC estimation correction and the coupling compensation of SOC estimation. The SOC initialization correction studies on correction when fully charged, correction with SOC-OCV curve and the improvement of SOC-OCV curve correction. The compensation of Li-ion battery SOC estimation studies on the compensation of battery charge and discharge efficiency, battery available capacity and environment temperature. Li-ion battery SOC estimation coupling compensation studies on the effect of coupling factors, coupling factors compensation method and application.