本文研製一具低損耗洩放電路之TRIAC調光LED驅動電路，包含一個單級返馳式轉換器和TRIAC洩放電路。由於LED燈泡接至TRIAC調光器上會產生的維持電流不足的問題，導致TRIAC調光器無法正常操作並使得LED閃爍，故並聯一組洩放電路以提供TRIAC調光器足夠之電流。通常使用之洩放電路會使用電阻來控制流過的電流量，此方法會產生較大的能量損耗。故本文使用一包含電感，電容和開關之洩放電路來提供TRIAC調光器電流，來避免能量消耗在電阻上。最後實作一輸入電壓為90~135 V的洩放電路，且能應用於7.2W LED驅動電路之調光。實驗目標為藉由洩放電路能提供定電流，使得TRIAC調光時能有足夠之維持電流用以獲得大範圍的導通角度，無閃爍現象發生，且調光穩定性高。

In this thesis, the analysis and implementation of LED driver for TRIAC dimming is presented, which includes a single stage flyback converter and a TRIAC bleeder circuit. The insufficient holding current problem will occurred when the LED driver is connected to the TRIAC dimmer, which will cause the TRIAC dimmer misfire and LED flicker. Therefore, a bleeder circuit is parallel connected to provide the TRIAC dimmer enough holding current. In the bleeder circuit, the resistor is usually used to control the amount of current flowing through the bleeder, and will cause high power loss on the resistor. In the thesis, a bleeder circuit with an inductor , a capacitor and switches is used to provide TRIAC dimmer extra current to reduce the power dissipation by using a resistor. Finally, the hardware type of the bleeder circuit with an input voltage of 90~135V is implemented, and be able to applied on the TRIAC dimmable 7.2W LED driver The bleeder circuit can provide constant current to fulfill the holding current requirement of the TRIAC conducting, which will widen the conducting angle of the TRIAC dimmer. When the TRIAC dimmer is applied, no flicker and misfire will occur.

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