評估具有鋰離子電池之太陽能逆變器中雙向CLLC諧振轉換器的控制方法

Abstract

將儲能系統整合到太陽能系統中有助於解決電力日益增多的需求之外，亦可解決再生能源間歇性的問題。由於太陽能板易受環境影響，因此有鋰電池之太陽能微型逆變器是一種解決方案，因整合的太陽能系統可提供更可靠的電力，並將之傳輸至電網。然而，這會導致更複雜的逆變器系統設計，因系統需要額外增加一個雙向直流轉直流的轉換器來對電池進行充電和放電。在該系統中，需要將適當的功率平衡控制來向電池傳輸能量與從電池取得能量，同時確保直流鏈電壓保持在可接受的電壓範圍內，從而正確地向電網供電。本研究驗證三種不同的雙向CLLC諧振轉換器控制方法，達到在整合鋰電池之太陽能逆變器中提供電池放電和充電模式之間的快速轉換。 在這此論文中，第貳章討論了對稱型的雙向CLLC轉換器的拓撲介紹，包括工作模式分析、共振腔的電壓增益和通過輸入阻抗分析的零電壓切換與零電流切換之邊界。第參章介紹了CLLC諧振轉換器的簡化穩態平面分析，提供一種更簡單方法觀察CLLC的工作模式。第肆章提出了鋰離子電池的仿真模型。由於CLLC諧振轉換器、鋰離子電池以及所提出的控制方式在文獻中很少被論及，因此在第伍章中介紹了三種動態平衡之電壓控制方法，並通過硬件在環系統驗證及比較三種功率平衡控制方法。第陸章討論包含雙向CLLC轉換器之硬體設計、CLLC電路之閉環測試、電路之穩態平面軌跡測試與效率測試等。 本論文獨特貢獻涵蓋: (1) 透過輸入阻抗推導CLLC轉換器之零電壓開關/零電流開關邊界、(2) CLLC轉換器之穩態彈道平面分析、(3)使用硬件在環驗驗證與比較三種動態電壓控制方法、(4) CLLC轉換器之硬體設計與(5) CLLC轉換器之開環與閉環測試。

The integration of storage into solar photovoltaic systems helps address the increasing electricity demands and the intermittent nature of renewable energy sources. Since photovoltaics (PV) are easily affected by environmental conditions, PV microinverters with integrated batteries are one solution to achieve a more reliable power output to the grid. However, this results in a more complex microinverter system design which requires an additional bidirectional dc-dc converter to charge and discharge the battery. In this system, proper power balancing control is required to transfer energy to and from the battery while ensuring the dc link voltage stays within an acceptable voltage to properly provide power to the grid. This research analyzes and evaluates three distinct system control methods of a bidirectional CLLC resonant converter together with Li-ion batteries to have a quick mode transition in the integrated microinverter. In this work, the validity of switching frequency control, charge control and dual phase shift control are verified by hardware-in-the-loop. The topology introductions of the CLLC converter, including the operating mode analysis, the voltage gain of the resonant tank and the ZVS/ZCS boundaries analyzed by input impedances, are discussed in chapter 2. The simplified steady-state state-plane analysis of CLLC resonant converter, which provides a easier way to observe the operation of CLLC, is mentioned in chapter 3. In chapter 4, the Lithium-ion battery's emulation model is introduced. As the CLLC resonant converter together with Lithium-ion batteries considering the three different controllers has not yet been fully investigated in the literature, the three controllers are introduced, their validity is verified using real-time hardware-in-the-loop system and comparison are discussed in chapter 5. In chapter 6, the CLLC hardware design, the closed loop (switching frequency control), the steady-state state-plane of the CLLC and the efficiency test are mentioned. The unique contributions of this work fully cover as follows: (1) the zero voltage switching/zero current switching boundaries derivation of the CLLC, (2) the steady-state state-plane analysis of the CLLC converter, (3) the hardware-in-the-loop verification and comparison of three controllers, (4) the hardware design of the CLLC converter and (5) the opened and closed loop test of the CLLC converter.