由於材料與製程快速進步，使得高亮度發光二極體應用於照明領域，且發光效率亦優於白熾燈泡。相較於螢光燈管，LED具備有許多好處，如使用壽命高於100,000小時、較寬廣的操作溫度-20℃~120℃以及較低且較安全操作電壓。一般照明應用上，單級LED驅動電路係採用不連續電流導通模式(DCM)之返馳式電路架構，藉以透過簡單電路架構而達到高功率因數及穩定燈管電流之目的。然而，不連續電流導通模式操作將產生較高之峰值電流與較嚴重之電磁干擾(EMI)問題。
本論文研製一種應用於照明LED之耦合電感SEPIC PFC轉換器。電路使用一般商用低價之邊界模式(BCM) PFC控制器，並將輸入電流操作於連續電流導通模式。本論文所提之單級LED驅動電路可同時達到高功率因數及高效率。此外，本論文除了說明電路控制法則及分析電路原理外，同時也提出設計實例，並實作出電路原型，再經由量測結果驗證所提理論正確性與電路實作之可行性。最後，再比較其與傳統單級DCM返馳式轉換器之效率。

The rapid advancements in new materials and manufacturing technologies have facilitated the use of high-luminance LEDs for lighting applications, and they have efficacies (lm/W) above those of incandescent lamp, which are growing to fluorescent efficacy levels. Compared with fluorescent lamps, LED lamps have numerous advantages, such as up to 100,000 hours of operation life, a wide range of temperature operation for -20C to 120C, and their ability to work with low and safe voltages. In general lighting applications, a single-stage discontinuous current conduction mode (DCM) Flyback power factor correction (PFC) converter is commonly used to drive LED lamps for achieving a high power factor and regulating lamp current with a simple circuit configuration. However, DCM operation causes high peak current stresses and serious electromagnetic interference (EMI) problem.
The thesis aims to study a coupled inductor SEPIC PFC converter topology for lighting LED driver. Continuous current conduction mode (CCM) operation on input current can be realized by using a commercial low-cost BCM PFC control IC. High efficiency and high power factor can be simultaneously achieved by the studied single-stage LED driver. The operation principles and design considerations of the studied LED driver are analyzed and discussed. A laboratory prototype is also implemented and tested to verify the feasibility. Finally, performance comparisons between the studied LED driver and the conventional single-stage DCM Flyback converter topology are also presented.

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