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ZHANG Fangliang.SOC Estimation Method for Lithium Ion Battery Based on Improved EKF Algorithm[J].JOURNAL OF POWER SUPPLY,2018,16(5):124-129
SOC Estimation Method for Lithium Ion Battery Based on Improved EKF Algorithm
Received:July 14, 2016  Revised:December 28, 2017
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Keywords:lithiumion battery  state of charge (SOC)  variable current  improved extended Kalman  estimation accuracy
Fund Project:Science and Technology Support Program of Sichuan Province
ZHANG Fangliang School of Manufacturing Science and Engineering, Southwest University of Science and Technology, Mianyang , China zfliang1030@foxmail.com
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      A novel estimation method based on improved extended Kalman filter(EKF) algorithm was proposed, which aimed at the low accuracy problem when estimating the lithium ion battery' state of charge(SOC) in the variable-current discharging process. First, though the discharging and hybrid pulse power characteristic(HPPC) experiments, the parameters of equivalent circuit model were analyzed and calculated. Then, the relationship among model parameters, discharge rate and SOC was obtained, and a novel principle and a novel method for estimating SOC were proposed, which were based on online correcting the open circuit voltage and ohmic resistance. Finally, the feasibility and effectiveness of the improved method were verified by the SOC estimation results in the variable-current discharging process. In this way, the proposed method can solve the low estimation accuracy problem of lithium ion battery under complex working conditions.