利用電流配置管理之並聯電池放電老化平衡技術

Abstract

隨著充電電池的使用次數增加，電池會越老化，其健康狀態(State of Health, SOH)越差。並聯電池組內部電池可能因製程上的差異，或封裝內各位置溫度差異的關係，造成彼此間健康狀態不盡相同，這種情形在包含上百顆電池的大型儲電系統特別顯著，隨著使用時間增加，電池間的健康狀態將越差越大，故當電池組淘汰時，內部除了已老化的電池外，還有一些尚且健康的電池，所造成的影響即是電池資源的浪費。本論文提出一個並聯電池老化平衡技術，係利用在不同放電電流下電池之滿電位容量下降斜率不同的特性，並考慮各電池環境溫度與放電深度等老化因素，進而分配各電池放電電流，以達成電池間老化進程拉為一致的目的，並藉由Matlab模擬結果證實此方法確實能令並聯電池老化平衡，且在壽命期間內比不作老化平衡能提供更多電量給載具，當電池間環境溫度差異達30℃，壽命期間可放出總電量增加率最大可增加300%以上。最後實作一小型電池儲電系統來實現本論文的演算法，各電池輸出電流最大誤差皆在1%以下。

Rechargeable batteries become aged with cycle number increasing. Since the difference of batteries in manufacturing process or using environment, SOH may be different from each other especially in a large electricity storage battery system combining hundreds of cells. As time increases, the greater the SOH difference between the batteries. There are some cells still healthy when the battery pack reaches end of life (EOL), causing battery waste problem. This paper proposes an aging equalization technology of parallel-connected batteries by current-sharing control to make remaining cycle of every battery the same according to the feature of full charge capacity (FCC) decreasing slope different with discharging rate, also considering other aging factors such as temperature and depth of discharge (DOD). Matlab simulation results confirm this approach does make parallel-connected batteries aging equalization, and battery pack can provide more energy to device than battery pack without equalization. The greater the difference of battery temperature, the greater the total power can be released up to 300%. A battery energy storage system is implemented with maximum discharge current error below 1%.