Energy Storage Science and Technology ›› 2021, Vol. 10 ›› Issue (6): 2352-2362.doi: 10.19799/j.cnki.2095-4239.2021.0169

• Energy Storage Test: Methods and Evaluation • Previous Articles     Next Articles

State of charge estimation of lithium ion battery based on parallel Kalman filter

Yi'nan ZHU1,2(), Taolin LÜ2, Zhiyun ZHAO1, Wen YANG1   

  1. 1.School of Information Engineering, East China University of Science and Technology, Shanghai 200237, China
    2.Shanghai Space Power Research Institute, Shanghai 200245, China
  • Received:2021-04-20 Revised:2021-07-17 Online:2021-11-05 Published:2021-11-03

Abstract:

The state of charge (SOC) of lithium-ion batteries is studied, and a parallel Kalman filter-based SOC estimation algorithm is proposed, with the goal of solving the problem of power display and life prediction in new energy electric vehicles. The Thevenin battery's first-order RC equivalent circuit model is defined. Data processing of open circuit experiments results in the static OCV-SOC relationship expression. The least-square method with a dynamic forgetting factor is used to identify the model's parameters. The maximum likelihood estimation criterion is used to make the model noise covariance self-learning, using the Ampere-hour integral method as the state transfer equation and the extended Kalman filter as the state transfer equation. Given that the model parameters change as the battery life declines, a parallel structure filter is designed to estimate the battery state and modify the parameters accordingly, ensuring the purity and independence of the data transmission and allowing SOC estimation throughout the life. The simulation results show that the algorithm has fast convergence and real-time performance, and the estimation accuracy is less than 2%.

Key words: electric vehicle, lithium-ion battery, extended Kalman filter, SOC estimation, dynamic forgetting factor

CLC Number: