A Robust Fast-Charging Methodology for Aging Lithium Batteries

• Main Authors: Fan, Po-Cheng, 范伯政
• Other Authors: Dung, Lan-Rong
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/74063981064080768190

碩士 === 國立交通大學 === 電機學院電機與控制學程 === 101 === While the battery is shipped out from the manufacturing factory and begins the charge/discharge cycles, the battery aging effect happens. Prevalent charging methods developed for charging new batteries do not take the battery aging effect into account, so it will not adaptively change the charging method as the aging of the battery. When the battery is charged and discharged for many times, the available capacity is less after charging and the operation time becomes shorter. The thesis propose an extend energy compensation charging method to let the aging battery has the same discharge energy as new battery does in the fast charge mode so that users will not feel the operational time is shorter when using aging batteries. The fast charge mode full charge the battery will only charge the battery fixed amount of charge or fixed power. After the battery has been through repeated charging and discharging, the battery starts aging and the internal impedance of the battery increases. As the internal impedance of the battery increases, a waste of energy in the impedance of battery during charging process becomes large at the same time. The result is that less energy can be retrieved from the battery and the required operation time is not matched. The charging method of extend energy compensation is to preserve the charging energy of the new battery in fast charge mode. To fully utilize the difference of charging energy between the aging battery and new battery during fast charge mode, the difference of charging and discharging and temperature compensation are applied to the calculation and compensate the lost energy of the aging battery. The benefits of the proposed charging method of extend energy compensation is that no prior information regarded to battery aging model is required. During battery charging process, the control for next step is calculated online and calculation is simple and convenient for charging system hardware implementation. Secondly, aging batteries charged by the proposed algorithm would provide same operating time as a new battery does. Finally, the capacity of the battery can be fully utilized, rather than using only part of the original fixed capacity range. Therefore the user perception of the battery operating time is maintained.