本論文採用在線式與離線式兩種內阻法來針對以電壓切換為準則的四階段定電流充電法進行鋰離子電池容量衰退的估測，在線式內阻法使用四個階段充電電流切換時的電壓變化與不同的電流值，再由歐姆定律求出電池內阻值，目的是了解電池在閉迴路時的內阻變化情形。而離線式內阻法使用四線式量測方式，因該法在量測內阻值時不會受到線材內阻的影響，由於電池內阻皆為微小變化，而使該方法能較精確的得知電池在開迴路時的內阻變化情形。由在線式與離線式兩種內阻法量測電池內阻的衰退情形得知，使用四階段定電流充電法對Sanyo 840 mAh之電池進行充放電循環達190次後，該電池容量會衰退至80%以下。為方便了解電池容量衰退之情形，本論文於Matlab中的模糊邏輯法中建立在線式與離線式兩種內阻參數規則庫，以方便使用者不需透過圖表，而可直接經由在線式與離線式的輸入值便能知道電池容量衰退之情形。

In this thesis, methods of measuring on-line and off-line internal resistances have been utilized to estimate capacity degradation of a Lithium-ion (Li-ion) battery when the battery is charged with the four-stage constant current charging (4SCC) strategy. Current-switch method is adopted to measure the on-line internal resistance by observing the change of the internal resistance of a Li-ion battery. This method takes advantage of voltage variations and current variations in each stage in order to figure out the change of the internal resistance in a close-loop circuit. As for the method to measure the off-line internal resistance, this study applies Kelvin Resistance Measurement to avert wire resistance, and to achieve higher accuracy during measurements. According to the measured on-line and off-line internal resistances, the capacity of the battery which used the 4SCC charging method will drop under 80% after 190 cycles. In addition, this study utilizes the Fuzzy logic toolbox in Matlab to build up two base rules. Without any actions, users could recognize the capacity degradation of a Li-ion battery by importing input variables from the on-line and off-line internal resistances.

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