Improved Realtime State-of-Charge Estimation of LiFePO $_{\boldsymbol 4}$ Battery Based on a Novel Thermoelectric Model

C. Zhang, Kang Li, Jing Deng, S. Song

Research output: Contribution to journalArticle

45 Citations (Scopus)


Li-ion batteries have been widely used in electric vehicles, and battery internal state estimation plays an important role in the battery management system. However, it is technically challenging, in particular, for the estimation of the battery internal temperature and state-of-charge (SOC), which are two key state variables affecting the battery performance. In this paper, a novel method is proposed for realtime simultaneous estimation of these two internal states, thus leading to a significantly improved battery model for realtime SOC estimation. To achieve this, a simplified battery thermoelectric model is first built, which couples a thermal submodel and an electrical submodel. The interactions between the battery thermal and electrical behaviors are captured, thus offering a comprehensive description of the battery thermal and electrical behavior. To achieve more accurate internal state estimations, the model is trained by the simulation error minimization method, and model parameters are optimized by a hybrid optimization method combining a metaheuristic algorithm and the least-square approach. Further, time-varying model parameters under different heat dissipation conditions are considered, and a joint extended Kalman filter is used to simultaneously estimate both the battery internal states and time-varying model parameters in realtime. Experimental results based on the testing data of LiFePO 4 batteries confirm the efficacy of the proposed method.
Original languageEnglish
Pages (from-to)654-663
Number of pages10
JournalIEEE Transactions on Industrial Electronics
Issue number1
Publication statusPublished - 15 Sep 2016
Externally publishedYes


  • battery management systems
  • cooling
  • electric vehicles
  • iron compounds
  • Kalman filters
  • least squares approximations
  • lithium compounds
  • minimisation
  • nonlinear filters
  • secondary cells
  • LiFePO4 battery realtime state-of-charge estimation
  • Li-ion battery
  • electric vehicle
  • battery internal state estimation
  • battery management system
  • battery internal temperature estimation
  • realtime SOC estimation
  • battery thermoelectric model
  • thermal submodel
  • electrical submodel
  • battery thermal behavior
  • battery electrical behavior
  • simulation error minimization method
  • hybrid optimization method
  • metaheuristic algorithm
  • least-square approach
  • time-varying model parameter
  • heat dissipation condition
  • joint extended Kalman filter
  • LiFePO4
  • Batteries
  • State of charge
  • Estimation
  • Temperature measurement
  • Temperature
  • Heating
  • Integrated circuit modeling
  • Internal temperature estimation
  • joint extended Kalman filter (EKF)
  • state-of-charge (SOC) estimation
  • thermoelectric model

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