鋰離子電池之高響應主動式電能等化管理系統

Abstract

動力鋰離子電池模組由許多電池芯組成，電能等化管理系統的主要目的是在充電或放電的過程中保持各電池芯的電能均等，以確保電池模組的效能、安全性、與充放電循環次數。本論文提出一種高響應主動式電能等化管理系統，特點是用超電容做為電池芯之間的電荷輸送元件，在充電或放電的過程中，控制單元會根據電池芯之間的電壓差異量操縱超電容電路，把電荷從電壓較高的電池芯輸送到電壓較低的電池芯，終而使各電池芯之間的電壓差異量達到最小化。本論文特別致力於開發縮減達成電能等化所需時間的相關技術，使電池模組可以適應快速充放電的應用環境，並且建構一個雙向電能等化管理系統試驗機，針對串並聯電池模組與並串聯電池模組驗證其標準(1C)與快速(5C)充放電等效能，實驗結果顯示此電能等化管理系統可以具體應用於動力鋰離子電池模組。

Cell equalization is the process of restoring all cells in a rechargeable battery to an equal sate of charge. Even though there has been considerable research effort to control the equalizing process of series-connected Li-ion cells, many improvements can be done in a more practical and efficiency-effective manner to enhance the electrochemical uniformity of the individual cells, to prolong the battery lifetime and to insure safe battery operation in automotive applications. The algorithm development is significantly more involved in order to shorten equalization time in cells capable of generating high power and being charged at constant current of between 4C and 5C rate in the fast charge mode. In this paper, a responsive active equalization with a charge shuttling unit, ultracapacitors, is presented to intelligently control the bidirectional equalization process. This shuttling algorithm can dramatically reduce equalization time up to 30% and it can be effectively achieved for each cell in the strings during fast charge mode. A prototype of twelve high power Li-ion cells with two most notable connections is implemented. Both the simulation and experimental results show that, the proposed algorithm demonstrates high capability of energy redistribution in fast charge conditions, together with state of charge determination.