並聯單相交直流轉換器之新型環流電流控制策略發展

Abstract

本論文提出了一個應用於並聯單相全橋交直流轉換器的新型環流電流控制策略，該策略可提升並聯系統的效能並且同時消去由於並聯所產生的共模與差模環流。基於所提出的控制策略，並聯系統的電流波形與功率分配可以達到改善。首先，本論文提出了一個簡易的前饋控制器，使得單一轉換器在獨自運作的情況下可以輕易的達到良好的輸入電流追隨與輸出電壓調節，另外本論文中定義了共模與差模的環流，並且列舉出雙轉換器並聯系統基於不同脈波寬調變策略下所產生的環流現象，並對於傳統單極性與雙極性脈波寬調變下所產生的環流建立環流模型。藉由對環流路徑的了解，進一步設計出共模與差模的環流控制器並由模擬驗證控制器與所建之環流模型的可行性及有效性。 最後，為了進一步了解控制器在實際情況下的可行性，本論文建立了一個雛形系統，以雙並聯的轉換器為基礎並且實驗所提出之控制器的可行性。透過實驗可得知本論文所提出的共模與差模環流控制器可使得雙轉換器的並聯系統在相同與不同的功率比之下達到好的電流分享與電流波形追隨。

In this study, a novel circulating current control scheme of parallel single-phase boost type full bridge converters is proposed. The novel circulating current control scheme improves the performance of the parallel system and reduces the common-mode and differential-mode circulating currents which result from the parallel connection. Based on this control scheme, not only input current shaping of each converter is improved, but also current sharing among paralleled converters is achieved. First, a simple feed-forward scheme is proposed to achieve better current shaping and voltage regulation. In the study, the common-mode and differential-mode circulating currents are defined and an analysis of the circulating currents in the two paralleled single-phase converter system is delivered. By understanding the phenomenon of circulating currents, a proposed circulating current control scheme is developed to reduce the circulating currents. Both simulation and experimental results verified the validity of the proposed circulating current control scheme.