- 學位論文
適用於多串LED背光之電流平衡驅動系統研製
Design and Implementation of a Current Balance Driving System for Multi-string LED Backlight
摘要
本論文係研製用於多串LED背光之電流平衡驅動系統，前級採用昇壓型功率因數修正轉換器，設計工作於臨界導通模式，具有高功率因數與柔性切換的效果，後級採用半橋諧振轉換器與一組昇壓型轉換器組合，實現驅動多串LED背光之電流平衡驅動系統。 半橋諧振轉換器具有一次側功率開關零電壓切換導通與二次側輸出整流二極體零電流切換截止的特性，藉由變壓器二次側多組繞組連接到各LED燈串，再利用一組昇壓型LED驅動器回授控制，以達到多串LED電流平衡的效果。 本論文所提之電路架構除了可兼具功率因數校正與LED電流平衡的功能，並與傳統主動模式平衡電路比較簡化之電路架構。最後以LED背光規格為3燈串、210V、260mA、輸入交流電壓90V~264V為設計規格，實驗結果驗證此LED背光驅動系統可以滿足設計要求，整體電源效率達86%、功率因數達0.97以上。
並列摘要
This thesis develops a current balance driver system for multi-string LED backligh. The first stage uses boost power factor correction converter operating in critical conduction mode in which power factor correction and soft switching are introduced to achieve high power factor and high efficiency. The second stage combines a half-bridge resonant converter and a boost converter. The current balance driving system can be implemented as the driving multi-string LED backlight. The half-bridge resonant converter has zero voltage switching on primary side power switches and zero current switching on the secondary side rectifier diodes. The secondary side windings of the transformer are connected to each of the multiple LED strings. The boost LED driver feedback control is used to achieve current balance for multi-string LED backlight. This thesis features power factor correction, LED current balance, a more simplified circuit topology. Finally, the design specifications for three string LED backlight include output voltage 210V, output current 260mA and AC input voltage 90V~264V. Experimental results verify that this system can meet the LED backlight driver design requirements. Power supply has efficiency up to 86%, power factor up to 0.97.