近年來，電動車及儲能系統的需求，促使鋰電池產業的快速發展。為了因應各種不 同應用、不同功率的需求，導致鋰電池陣列的電壓分布範圍甚廣，一般情況可從 200V 到 1000V，這也驅使具寬廣輸出範圍充電器的研究。然而，高充電器輸出電壓範圍與高 轉換效率並不容易兼顧，為此，本論文從提升系統配置的彈性出發，提出將多個充電器 串聯，使得當充電器運行於恆流模式時可達到充電器輸出電壓的平衡的作法，以實現寬 廣輸出電壓的目的。同樣為達到高配置彈性，充電器(轉換器)的並聯均流已發展逾 20 載，但串聯均壓功能則鮮少研究提及，本論文因此將研究主題放在充電器運行於 CC 模 式且串聯使用時的輸出電壓平衡分析。完整的分析步驟包括充電器的小信號模型建構， 充電器串聯電壓不平衡的現象解釋，均壓控制的設計準則，以及串聯系統與負載的交互 作用。本文利用一般的硬切全橋轉換器實現充電器功能，提出可準確預估包含變壓器漏 感效應的小信號模型，並據此得到充電器運行於恆流模式下的諾頓等效電路，用以解釋 充電器串聯時的不均壓現象。經由分析可知，若欲降低串聯電壓不平衡的現象，可以降 低高輸出電壓的充電器之輸出電流或輸出阻抗，反之，可提高具低輸出電壓的充電器之 輸出電流或輸出阻抗。利用此規則，本文提出平均輸出電壓均壓控制法，藉由回授串聯 系統的平均電壓值來調節充電器的輸出電流，以縮小輸出電壓與平均電壓的差異，進而 達到充電器串聯均壓功能。經由完整的系統電路分析，可得到包含均壓補償器的虛擬迴 路，應用此虛擬迴路，再搭配自動控制的理論，可設計出能實現穩定的充電器輸出均壓 的均壓補償器;另外，本文亦推導出用以分析充電器和負載間的交互作用的判斷式，此 判斷式包含串聯系統的輸出阻抗以及負載的輸入阻抗，可做為另一個虛擬迴路，此虛擬 迴路可用以分析充電器連接負載後的系統穩定。經由上述設計準則，本文利用兩個充電 器串聯以驗證結論的準確性，首先，利用均壓補償器的設計準則，實現具不同迴路頻寬的充電器均壓功能，由虛擬迴路所得到的系統特性與實驗結果的比較，可知本文推導結 果的正確性。其次，利用串聯系統的輸出阻抗，以及負載的輸入阻抗，本論文亦可準確 預估當串聯系統連接到負載後，整個系統的穩定性。因此，利用本論文的研究結果，除 可實現均壓功能外，亦可得到具高響應速度、高穩定性的充電器串聯均壓系統。

In recent years, the demand for electric vehicles and energy storage systems has led to the rapid development of the lithium-ion battery. In order to meet the needs of various applications and different powers, the voltage range of lithium-ion battery arrays is very wide, generally ranging from 200V to 1000V, which also drives research of charger with wide range of output voltage. However, it is not easy to satisfy both the high output voltage range of the charger and the high conversion efficiency. From the perspective of increasing the flexibility of system configuration, this dissertation proposes a method to connect multiple chargers in series to expand the output voltage and achieve the balance of the output voltage of each charger when operating in constant current mode. In order to achieve high configuration flexibility, current sharing of chargers (converters) connected in parallel has been developed for more than 20 years, but voltage balance of chargers connected in series is rarely mentioned in the study. Therefore, the research topic of this dissertation is putting on voltage balance analysis and control when chargers are operating in CC mode and connected in series. The complete analysis steps include the construction of the small signal model of the charger, interpretation of the phenomenon of voltage imbalance in the series of chargers, design criterion for voltages balance control, and analysis of interaction between series chargers and load. A general hard-switching full-bridge converter is used to realize the charger function, and a small-signal model that can accurately estimate the leakage inductance effect of the transformer is proposed. The Norton equivalent circuit of the charger operating in constant current mode is obtained to explain the voltage imbalance phenomenon when the chargers are connected in series. According to the analysis, if we want to reduce the series voltage imbalance, we can decrease the output current or output impedance of the charger with higher output voltage, on the contrary, we can increase the output current or output impedance of the charger with lower output voltage. Using the rule, this dissertation proposes the average voltage balance control strategy to minimize the difference between the output voltage and the average voltage of the system by feeding back the average voltage of the series system to each charger to regulate output current of the charger and achieve the voltage balance function. Through a complete analysis of the system, the virtual loop gain including the voltage balance compensator can be obtained. Applying this virtual loop gain, combined with the theory of automatic control, the voltage balance compensator that can achieve charger output voltage equalization can be designed. In addition, this dissertation also derives an equation for analyzing the interaction between the charges and the load. The equation includes the output impedance of the series system and the input impedance of the load. It can be used as another virtual loop gain. This virtual loop gain can be used to estimate system stability when the charger system is connected to the load. Through the above design criteria, this dissertation uses two chargers in series to verify the accuracy of the conclusion. First, using the design criterion of the voltage balance compensator to realize the series charger system with different voltage balance bandwidth, the theoretical results are compared with the experimental results. The results show the correctness of the conclusion. Next, using the output impedance of the series system and the input impedance of the load, the other virtual loop gain also accurately predicts the stability of the overall system when the series system is connected to the load. By using the methods proposed in the dissertation, the system of chargers in series not only has voltage balance function, but also has high response speed and high stability.

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