State-of-Charge Estimation of Lithium Iron Phosphate Battery Using Grey Theory

• Main Authors: Geng-da Lin, 林庚達
• Other Authors: Jyh-horng Chou
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/10843025183841468003

碩士 === 國立高雄第一科技大學 === 系統資訊與控制研究所 === 99 === The lithium iron phosphate battery is a promising power source for electric vehicles (EVs) and hybrid electric vehicles (HEVs) due to its high specific energy and power. To ensure the batteries be reliable and capable of delivering power and energy when required, an accurate determination of available capacity, i.e., state-of-charge (SOC), is necessary. Moreover, it will prevent the battery from being over-charged or over -discharged and manage the energy flows of the vehicle. This research describes a real-time SOC indication method which combines open-circuit voltage, Coulomb counting method, and grey prediction technique. The open-circuit voltage battery is measured only once when the battery pack is in stabilized state over 30 minutes. Then the initial SOC estimation is performed and the successive estimation is calculated by grey prediction of current and Coulomb counting. Finally, the proposed methodology was implemented on a dsPIC embedded processor and experimental results verify its effectiveness and feasibility.