本文主要為研製一單級高功因LLC諧振電源轉換器，電路拓樸中包含升壓型功因校正單元以及對稱半橋式LLC諧振直流/直流轉換單元。升壓型功因校正單元將升壓電感操作在不連續導通模式來達到自發性功因校正之功能。而轉換器之切換頻率是操作於L-L-C所構成的諧振頻率以上使得一次側開關達到零電壓切換、二次側整流二極體達到零電流切換，可提高轉換效率。此外，本文採用變頻控制以維持輸出電壓穩定並有效減少儲能電容電壓所造成的開關應力。除了轉換器之工作原理分析與討論之外，本文以電腦模擬與實驗結果來驗證理論之正確性。實驗證明轉換器擁有最高效率91%，在所有負載範圍內功因皆達到0.99以上並且符合IEC 1000-3-2 Class-D之諧波規範。本文所提單級高功因LLC諧振電源轉換器具有架構簡單、低成本、變頻控制、高功因、高轉換效率等特點。 A single-stage LLC resonant converter with high power factor is proposed in this thesis. The proposed converter consists of a boost-PFC cell and a symmetrical half-bridge LLC resonant dc/dc cell. The boost- PFC cell works in discontinuous conduction mode (DCM) functions for achieving self-PFC. The switching frequency of the proposed converter is designed to be higher than the L-L-C resonant frequency, resulting in zero voltage switching (ZVS) on primary power switches and zero current switching (ZCS) on secondary rectifier; hence one can improve the conversion efficiency. Furthermore, a variable frequency controller is adopted for achieving output voltage regulation of the proposed single-stage LLC resonant converter and suppressing the voltage of bulk capacitor. Besides, the operating modes and dc characteristics are discussed for designing the proposed converter. Finally, the computer simulations and experimental results verify the performance as theory prediction. The proposed converter successfully meets IEC 1000-3-2 Class-D requirements and the conversion efficiency can be achieved up to 91% under rated condition. The proposed single-stage LLC resonant converter has the features of simple structure, low component count, variable-frequency control, high power factor, and high efficiency.
