可相容TRIAC調光器之無閃爍及高功因LED數位初級側控制驅動系統

Abstract

為了取代即將被淘汰的白熾燈調光系統，TRIAC調光器與LED燈泡的結合為近年來各大廠商努力研發的方向，然而此結合存在著許多的問題，例如:TRIAC的維持電流(Holding current)、因被動元件而產生的電流震盪以及在TRIAC調光位置固定下導通角度會隨著市電波動影響等都會使LED燈泡的發光穩定性下降。為了克服上述所提出之問題，本文加入被動阻尼器及數位式輸入電壓補償機制來改善震盪電流及調光命令受市電擾動影響之問題。 除了針對TRIAC調光器之問題做改善之外，本文為了提高隔離型LED燈泡之競爭力加入了初級側控制架構，不但大幅簡化外部所需之零件數，並可提高整體電路可靠度及降低成本。估測次級側二極體平均電流可由初級側峰值電流及二極體導通時間計算出，而二極體導通時間偵測機制上利用輔助繞阻電壓的零交越訊號計算時間長度並對不連續導通模式下磁化電感去磁區間做震盪時間偵測且補償。 在效能方面為了符合功率因數之規範，本文加入主動式功因修正控制並採用數位類比混合式控制架構，外迴路為數位控制包含初級側電流控制及TRIAC電流命令偵測，而內迴路為類比峰值電流控制。最後實驗部分加入LT3799及白熾燈做為比較對象，針對一可調光LED驅動系統相關效能曲線做比較並分析其差異性及討論。

In order to replace incandescent lamp dimming system, LED light bulbs with TRIAC dimmer is one of main stream research in recent years, but there are many problems for combination of LED and TRIAC, such as: TRIAC’s holding current、current resonant generated by passive components, and the conduction angle fluctuated with line voltage. To overcome the above problems, the passive damper and digital input voltage compensation for dimming command are proposed to improve the problems mentioned above. The primary-side sensing architecture is adopted in this thesis, not only greatly simplifies the number of external components required, and improves overall circuit reliability and low costs. The output average current can be estimated by primary side peak current and the secondary side diode conduction time, the secondary side diode conduction time detection mechanism join the resonant time of demagnetization interval compensation that can increase the estimation accuracy. The thesis adopts active power factor correction control and use digital and analog hybrid control architecture. Finally, the experiment results of the thesis proposed will compare with LT3799 and incandescent lamps to analysis the different and discussions.