Charging Pattern Optimization for Li-Ion Fast Chargers

• Main Authors: Chu Shun-I, 朱順義
• Other Authors: Jen-Hao Teng, Ph.D.
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/71214223142328112784

碩士 === 義守大學 === 電機工程學系 === 92 === Recently, the number of portable personal telecommunication systems such as mobile phones and laptop computers has grown explosively. Secondary batteries are often used in these equipments because they are cost-effective over the lifetime of the product. Among these, lithium-ion (Li-ion) batteries are growing at a rapid rate in response to environmental concerns and the need for higher energy density. The performance and longevity of lithium ion batteries depend, to a large extent, on the quality of their chargers. Commercially available fast chargers are often not designed in the best interests of the battery. Therefore, it is important for battery manufacturers to determine the optimal charging pattern for their products. Several efforts have been devoted to study the charging techniques and charging patterns. From those methods, multi-stage pulse charging algorithm is proven to have the advantages such as prolong cycle lives, enhance discharge/charge energy efficiency, and reduce the charging time. However, the optimal current value for each stage still cannot be determined. In order to search the optimization charging pattern for multi-stage pulse charging algorithm, a rapid charger designed based on CPLD (Complex Programmable Logic Device) is implemented in this thesis. A human-machine interface designed by LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is also implemented to set the charging currents and monitor the charging status. A searching algorithm for charging pattern based on Taguchi method and orthogonal array is then proposed for Li-ion batteries in this thesis. Due to the characteristics of Taguchi method and orthogonal array, the experimental number required for charging pattern searching can be minimized. Experimental results show that the obtained rapid charging pattern is capable of charging the lithium-ion batteries to 60% capacity in 30 minutes.