The State of Charge Estimation for Lithium-Polymer Battery using a PI Observer

PI 상태관측기를 이용한 리튬폴리머 배터리 SOC 추정

  • Lee, Junwon (Dept. of Electrical Engineering, Chungnam Nat'l Univ.) ;
  • Jo, Jongmin (Dept. of Electrical Engineering, Chungnam Nat'l Univ.) ;
  • Kim, Sungsoo (Dept. of Mechatronics Engineering, Chungnam Nat'l Univ.) ;
  • Cha, Hanju (Dept. of Electrical Engineering, Chungnam National University)
  • Received : 2015.01.23
  • Accepted : 2015.03.06
  • Published : 2015.04.20


In this study, a lithium polymer battery (LiPB) is simply expressed by a primary RC equivalent model. The PI state observer is designed in Matlab/Simulink. The non-linear relationship with the OCV-SOC is represented to be linearized with 0.1 pu intervals by using battery parameters obtained by constant-current pulse discharge. A state equation is configured based on battery parameters. The state equation, which applied Peukert's law, can estimate SOC more accurately. SOC estimation capability was analyzed by utilizing reduced Federal Test Procedure (FTP-72) current profile and using a bi-directional DC-DC converter at temperature ($25^{\circ}C$). The PI state observer, which is designed in this study, indicated a SOC estimation error rate of ${\pm}2%$ in any of the initial SOC states. The PI state observer confirms a strong SOC estimation performance despite disturbances, such as modeling errors and noise.


Grant : 그린카 부품 상용화지원을 위한 가상개발환경(VIDE) 개발

Supported by : 산업통상자원부


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