應用於直流-直流轉換器之可重組電池陣列電壓平衡方法

Abstract

本論文提出了一種可重組電池陣列(Reconfigurable Battery Array,RBA)應用於直流-直流轉換器的電池電壓平衡控制方法。對電池模組而言，由於可重組電池陣列中電池與電池之間固有的差異性，且電池模組工作在不同模式時，輸出/輸入功率差異較大，很容易造成電池電壓不平衡的狀況。可重組電池陣列中的單個電池模組，可以含有三種不同的工作模式：恒導通模式，PWM模式，以及旁路模式。應用於RBA直流-直流轉換器時，處於恒導通模式的電池模組放電/充電速度最快，處於PWM模式的電池模組放電/充電速度其次，而處於旁路模式的電池模組則無放電/充電速度的操作。當各個電池模組持續操作在單一工作模式下時，就會造成電池組間電壓不平衡現象，甚至出現過度放電/充電的狀況，對電池造成永久性損害。為了解決RBA直流-直流轉換器中，電池電壓不平衡問題，本論文提出利用責任比(duty ratio)，推測出各個電池組相對電壓的方法。然後根據相對電壓的大小，讓各個電池模組改變工作模式，來改變電池組的放電/充電速度，從而達到電池平衡的效果。 本論文提出的方法，不論在平衡初始電壓下，還是不平衡初始電壓下，通過一定時間的放電/充電，都能達到電池電壓平衡的效果。此外，本論文提出的方法優點在於利用電路中固有的放電模式輸出電壓偵測電路，和充電模式輸入電流偵測電路，便能獲得足夠的控制資訊，不需要增加額外的偵測電路。本論文中，首先會介紹RBA直流-直流轉換器的電路架構和操作原理。接著說明責任比偵測平衡法的控制流程。最後基於含4個電池模組的可重組電池陣列系統，對於直流-直流轉換器的應用，進行模擬與實作。並驗證本論文所提出之電池電壓平衡方法的正確性。

A voltage balance method for the Reconfigurable Battery Array (RBA) for DC-DC converter applications is proposed in this thesis. For battery modules, due to the inherent varieties between batteries in RBA and the different output/input power of working modes, the voltage imbalance occurs easily. The battery module has three working modes: enable mode, PWM mode, and bypass mode. When the RBA DC-DC converter is operated under discharging/charging state, the battery module in enable mode has the fastest discharging/charging speed, followed by the one in PWM mode. For the Bypass mode, there is no discharging/charging operation. The different working modes have the different discharging/charging speed, which can easily cause permanent damage to the battery. In order to solve the battery imbalance problem of the RBA DC-DC converter, this thesis proposes a method of detecting the relative voltage of the battery cells according to the duty ratio. Then, according to the relative voltages, make these battery modules work in different modes with various discharging/charging speeds. The method proposed in this thesis can achieve the battery equalization under the conditions of both balanced or unbalanced initial voltages. In addition, no additional voltage or current sensors are needed. In this thesis, the circuit structure and operation principle of the RBA DC-DC converter will be introduced. Then, the control flow chart of the proposed duty ratio sensing balabce(DSB) method will be illustrated. Finally, the computer simulation and hardware experimental results of the prototype RBA DC-DC converter with four battery modules are built and tested to verify the performance of the proposed DSB method.