磷酸鋰鐵電池放電行為之數學模型建立

Mathematical models for the discharging behaviors of Lithium iron phosphate battery in various conditions

邱煒琍(Wei-Li Chiu)

指導教授 ： 李坤彥

國立臺灣大學/工學院/工程科學及海洋工程學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.01940

摘要

磷酸鋰鐵電池LiFePO4，為三維橄欖石結構的二次電池，具有輕巧、高功率、高容量、壽命長、高安全性等優點，廣泛運用於電動巴士、電動車、油電混合車、電動自行車、電動摩托車與太陽能電池之儲能裝置，由於環保意識的抬頭，與磷酸鋰鐵電池LiFePO4有關的產業正蓬勃地發展，為了研究此電池放電的特性以及老化對電池的影響，本論文利用定電流20A放電取得磷酸鋰鐵電池的放電曲線，藉以研究電池老化對電池放電性能的影響，而放電電壓曲線的取得是藉由LABVIEW於定電流放電時即時地紀錄，為了確保磷酸鋰鐵電池的健康並減少實驗進行時對電池內部造成影響，本論文也研製一充電控制器應用於放電實驗前，能對電池有效充電且避免電池過充而造成損害。
為了分析電池老化對電池放電性能的影響，磷酸鋰鐵電池放電曲線的捕捉便格外地重要，由於磷酸鋰鐵的閉迴路電壓以及內阻在不同的電池狀態下有著非線性的變化，為了捕捉這段非線性關係，本論文採用兩個數學模型擬合磷酸鋰鐵電池的放電電壓，用以得出數學模型的係數，此二個數學模型皆是建立在等效的電路架構的基礎上推導而來，其一為單指數與多項式項數學模型，另一為雙指數項數學模型，這些數學模型的係數可作為參數值來描述電池放電曲線的特性，藉由擬合不同狀態(使用多次與放置多年)之磷酸鋰鐵電池的放電電壓曲線，則可得出不同條件與不同狀態下電池的參數值，本文建立之參數表可用於判定電池之年份以及電池的使用次數，並在最後提出了一套系統預測已知年份電池之放電曲線。

關鍵字

磷酸鋰鐵電池 ； 趨近線擬合 ； 放電行為模擬

並列摘要

Lithium iron phosphate battery LiFePO4 is the three-dimensional structure of secondary battery, and widely used in electric buses, electric cars, hybrid cars, electric bicycles, energy storage devices and solar electric motorcycle battery. As environmental consciousness, thr LiFePO4 lithium iron phosphate battery-related industry is booming developed. In order to research the battery discharge characteristics and aging effects on the battery, this thesis set 20A discharge current to obtain lithium iron phosphate battery discharge curve. The discharge curve is obtained by constant current when LABVIEW on record its voltage discharge in time.
In order to analyze the impact of aging on battery performance battery discharge, lithium iron phosphate battery discharge curve records become exceptionally important. Because the open-circuit voltage and internal resistance of lithium iron phosphate has a non-linear changes in different battery capacity. To capture this nonlinear relationship between segments, this paper uses mathematical models to fit two lithium iron phosphate battery discharge voltage to draw mathematical model coefficients, this two mathematical models are all based on the equivalent circuit models. One for a single exponential and polynomial mathematical model and the other is a double exponential mathematical model, the coefficients of these mathematical models can be used as a parameter value to describe the characteristics of the battery discharge curve, by fitting different conditions.

並列關鍵字

Lithium iron phosphate batteries ； curve fitting ； discharge behavior simulation

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