適應性電容式電池平衡管理演算法研究

Abstract

近年來為了降低對於地球環境的傷害與減少交通運輸對於石油的依賴性，許多產業開始積極投入電動車與油電混合車產業，並使用鋰離子電池模組作為其主要動力來源，而電池所佔的成本居高不下，因此如何提高電池的利用價值便成為電池管理的熱門話題。然而為了因應使用需求，通常會將電池芯互相串並聯構成龐大的電池組，長期使用下便會發生各電池芯老化程度不一的情形，老化電池將影響整串電池組的使用，若是不妥善管理電池將會使電池組老化情形更為惡化，因而發展出了電池平衡管理技術。過去對於電池平衡管理只講求平衡電池端電壓或是電池電量狀態的差異，並沒有從實際電池使用的角度去觀看電池平衡這項事情。本論文所提出的適應性電容式電池平衡管理演算法以電池組放電使用的結果去解釋平衡的意義，並針對磷酸鋰鐵電池隨老化程度不同而表現出的充放電特性差異，有別於以往在電池靜置時長期操作平衡電路，本論文使用充電平衡方式將可大量節省平衡電池所需花費的時間，並提出一套能隨電池老化狀況適應性調整的電容式平衡啟動演算法，使電池組經過平衡後能後達到正確且有效的平衡目的，讓電池組保持在最佳的電池續航力狀態，並能降低電池的平均使用放電深度以增加電池組使用循環次數，同時避免電池組的老化效應持續增長。利用此演算法所實驗的結果有效增加7.3%電池所充入電量，並使電池增加1.5%放出電量。

In recent years, as energy-saving and environmental protection were widely concerned around the world, the LiFePO¬4¬¬¬ battery has been widely used in hybrid electric vehicle (HEV) and electric vehicle (EV). Because of the high cost of the Li-ion battery, how to extend the value of the battery is becoming a hot issue. Generally the battery pack for HEV is composition of the number of cells in series. In this case, unbalancing among cells due to the degradation, temperature etc, will be accelerated by the cycles of charge and discharge without an appropriate battery equalization management system. However, the balancing system only intended to reduce the difference of cell voltage or Stage of Charge (SoC) before. “Adaptive Battery Equalization Algorithm for Capacitor-based Battery Management System” this thesis proposed re-explains the meaning of battery equalization. Instead of long-term using battery equalizer on standby, this thesis equalizes the battery when charging to save much spending time. It could not only adjust the balancing mechanism automatically in order to keep the available charge but also raise the average SoC to prevent the effect of battery aging and improve the cycle number of battery. Experiment results indicate that the available charge increases 1.5% and the battery capacity efficiently improves 7.3%.