在三原色發光二極體混光應用中，傳統上大多採用三組轉換器並聯且分別控制紅光、綠光、藍光發光二極體以達到調光控制，然而此種做法有高成本、電路體積大及低效率等缺點。本論文設計與研製一多輸出可調光發光二極體返馳式驅動電路，二次側開關的導通次序及導通時間由一次側數位信號處理器傳遞之電壓準位決定。於不同輸出功率及輸入電壓時，返馳式轉換器採用一次側控制法可操作於準諧振模式、限頻模式及降頻模式以提升電路效率。最後，研製一20 W之紅光(24.5 V/ 0.2 A)、綠光(36.8 V/ 0.2 A)、藍光(37.5 V/ 0.2 A)可調光發光二極體驅動電路，調光範圍為5 % - 100 %，並可應用於市電輸入電壓90-264 Vrms，實驗結果顯示於5 % - 100 % 調光時輸入電壓調整率小於7 %，在非調光 (100 % 調光)及調光狀態下之最大誤差各為2.9 mA及3.6 mA，滿載輸出之效率最高可達85.54 %。

In tradition, three independent converters are built in parallel to perform color mixing and dimming control for red (R), green (G), and blue (B) light mixing applications. However, this method will suffer from high cost, large size, and low efficiency. In this thesis, a multiple-output dimmable LED driver with flyback converter is designed and implemented. The sequences and conducting times of RGB switches are determined by the voltage level from the primary-side digital signal processor. The flyback converter with primary-side control is operated in quasi-resonant mode, frequency limitation with the valley switching mode, and frequency reduction mode according to the output power and input voltage conditions. Finally, a 20 W flyback LED driver for red (24.5 V/ 0.2 A), green (36.8 V/ 0.2 A), and blue (37.5 V/ 0.2 A) LED outputs with the universal input voltages 90-264 Vrms is designed and implemented. The dimming range for each output can be varied from 5 % - 100 %. The line regulation for 5 % - 100 % dimming level of RGB outputs is within 7 %. The maximum errors for the non-dimming (100 % dimming) and dimming conditions are 2.9 mA and 3.6 mA, respectively. The highest system efficiency at full load condition is 85.54 %.

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