具熱效應之鋰電池單元/模組實驗量測與即時動態模型建立

Abstract

本論文之研究目的為磷酸鋰鐵電池單電池/電池並聯之動態量測與分析，並建立一具有溫度效應之鋰電池即時動態模型。本研究使用3.3V/ 2.3Ah之電池作為實驗樣本，充/放電電流設定為1C(2.3A)與2C(4.6A)，並將環境溫度控制於攝氏0度、20度、40度、60度等四個溫度下分別進行充/放電實驗、交流阻抗分析及熱效應實驗，利用實驗所得之數據，建立一5元件(Rs、Ls、Cp、Rp、W)之等效電路，並將實驗結果利用等效電路進行參數鑑別，最後透過Matlab/Simulink軟體建構一具溫度效應之鋰電池動態模型，其中電池之熱容量與熱傳係數藉由電池雙階段熱動態實驗法鑑別出，可建構出一階熱動態模型。 單電池實驗與具熱效應電池模型模擬結果顯示:固定電流充電與變動電流放電之模擬結果與實驗結果趨勢相近，系統參數將隨不同SOC與溫度做即時變化。固定電流充電輸出電壓平均誤差與溫度變化誤差各為xx%、yy%；變動電流放電輸出電壓平均誤差與溫度變化誤差各為xx%、yy%，因此表示此模型可成功模擬電池細部動態。而在並聯電池與單電池實驗結果顯示:同樣C-rate與溫度之充放電條件下，並聯電池之電容量較單電池低。而交流阻抗實驗顯示串聯電阻值較單電池為高。未來將延伸串聯電池實驗以建構電池系統之熱動態模型，以供電動車進行電池系統開發。

關鍵字：磷酸鋰鐵電池、溫度效應、交流阻抗、系統建模、等效電路This research studies experimental measurement for a unit cell/parallel module of lithium-iron-phosphate battery, and an on-line lithium battery dynamic model with thermal effect was constructed. We used a 3.3V/2.3Ah battery for the sample. The operation conditions were set to be 1C(2.3A) and 2C(4.6A), and 4 controlled temperatures of 0℃, 20℃, 40℃, and 60℃. Experiments for charge and discharge, AC impedance analysis, and experiments of thermal effect were conducted. Using the measured data, a 5-element (Rs、Ls、Cp、Rp、W) equivalent electric circuit was derived as well as the identification of parameter values. Sequentially, through the Matlab/Simulink software package, a lithium battery dynamic model with thermal effect was built. The heat capacity and heat transfer coefficient were derived by a two-step thermodynamics experimental method. A first-order thermal dynamic model was established. From the experimental results and the battery model with thermal effect of the unit cell, it show that: the simulation and experimental results are fitted well under the scenarios of constant charging current and varying discharge current. The system parameters change on-line with varying SOC and the temperature. The average errors of battery voltage and battery temperature in the constant charging current case were xx% and yy%; while those in the varying discharging current case were xx% and yy%. It indicates that the model can successfully simulate the detailed battery dynamics. Comparing the experimental results between parallel module and the unit cell cases: under the same C-rate charge/discharge and battery temperature, the electric capacity value of parallel module is lower. The AC impedance results demonstrated that the ESR value was smaller. The serial module experiment will be further conducted for the purpose of developing the battery systems in electric vehicles in the near future.

Keywords： lithium-iron-phosphate battery、thermal effect、ac impedance、modeling、equivalent electric circuit