The security guaranteeing method for the lithium-ion battery is studied and a novel state ofcharge (SOC) estimation method is proposed based on the Kalman filtering (KF) thought, aiming toguarantee its safety in the power supply application of electric vehicles (EVs). In this study, there areseveral parts that have been studied to realize the protection of the lithium-ion battery during its wholelife period. Firstly, the core parameters for the working state estimation of the lithium-ion battery isstudied and the methods for the state of charge estimation are analyzed. Secondly, the working state ofthe lithium-ion battery is estimated by the integrated application of the state of charge estimationmethods. Then, the estimation model is designed and realized based on the estimation principle. Atlast, this method and model is proved by the experimental analysis. In the experiments, the mainoperating temperature varies between 26.84 and 33.16 with an average value of 30 Theaverage value of the Coulomb efficiency is about 0.97 and all above 0.95. The average value of thebattery capacity is approximately 45.08Ah. When the SOC actual initial value is 0.8 and the test initialforecast value is 0.6, the estimation can track the actual value in less than 5 seconds and has high-6 accuracy. The error covariance value is smaller than 3.510 and decreases rapidly as time goes. Thisstudy can achieve the working state estimation of the lithium-ion battery, which can guarantee itssafety effectively in the power supply applications.
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