| Title |
The State of Charge Estimation for Lithium-Polymer Battery using a PI Observer |
| Authors |
Junwon Lee ; Jongmin Jo ; Sungsoo Kim ; Hanju Cha |
| DOI |
10.6113/TKPE/2015.20.2.175 |
| Keywords |
Lithium-polymer battery; State-of-charge; PI observer; Battery parameter estimation |
| Abstract |
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 °C). The PI state observer, which is designed in this study, indicated a SOC estimation error rate of ± 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. |