可调光的初级反馈LED驱动器的研究

Research on Dimmable Primary-side Feedback LED Driver

根据发光二极管（LED）照明电源体积小、成本低、可调光的要求，将初级反馈技术及模拟调光技术应用到LED电源驱动中。分析了单级功率因数校正（PFC）拓扑下初级恒流控制原理，同时推导了在准谐振工作模式下单级PFC拓扑的电流、功率因数和总谐波畸变率（THD）的计算公式，详细给出了在该工作条件下的变压器设计方法。最后制作了最大输出39V，1100mA的LED驱动器。结果表明，该驱动器在市电输入220V时，整机效率为91％、功率因数为0．99，并在10％-90％的输出范围内，电流精确可调。

Aiming at the small size, low cost and adjustable light requirements of the LED driver,the primary-side control and analog dimming technology are integrated in this LED driver.The principle of constant primary-side con- trol is analyzed,and the power factor k and THD are deduced of the high-A flybaek converter.Then a method of transformer designing is proposed after analyzing output current under quasi-resonant mode.Finally,a maximum output of 39 V, 1 100 mA LED power supply is made,and the experiment test shows that the efficiency is 91% and power factor can reach 0.99,output current adjustable accurately within the scope of 10% to 90% of the output.