多輸入單級式雙向市電併聯換流器

Abstract

本論文提出一種新型多輸入單級式雙向市電併聯換流器。電路架構中結合多組直流-直流升降壓轉換器以及一組直流-交流展開器，由於電能轉換的過程只需要一個功率開關進行高頻切換，因此具有單級式高轉換效率特性，亦可簡化其控制器設計。當此換流器應用在市電併聯之太陽能系統時，可達到分散式最大功率點追蹤，降低遮蔽效應之影響，進而提升整體發電效益。另外，當此換流器應用在市電併聯之電池儲能系統時，可獨立控制各個低壓電池模組之充電或放電功率，同時也達到電池組間平衡與市電併聯輸出電流控制。本論文亦利用輸入電壓與脈波調變寬度來推算平均電流的方法，以取代傳統電流感測器，並實現各個轉換器輸出功率之獨立控制功能，節省整體電路成本，同時使用交錯式的開關切換方法來改善輸出電流漣波與電感尺寸。最後，透過電腦模擬與實驗結果驗證本論文所提出之換流器分別應用在太陽能系統與電池儲能系統之性能。

The objective of this dissertation is to propose a multi-input single-stage bi-directional grid-connected inverter (MSBG-inverter). The proposed MSBG -inverter is composed of multiple buck-boost type dc-dc converters (BBCs) and a dc-ac unfolder. Because there is only one switch operating at high frequency, single-stage conversion with circuit simplicity and higher efficiency can be achieved. For photovoltaic (PV) system application, the MSBG-inverters can eliminate the shading effect while fulfill the functions of dc-ac conversing and the distributed maximum power point tracking (DMPPT). For battery energy storage system application, the MSBG-inverters can realize individual power-handling capability while fulfill the functions of battery charging and discharging. Moreover, based on the developed equations, the power flow of the BBCs can be controlled without the need of input current sensor. Also, with the interleaved operation between BBCs, the current ripple of the output inductor can be reduced too. Finally, the computer simulations and hardware experimental results are shown to verify the performance of the proposed MSBG-inverter for the PV system and the battery energy storage system.