- 學位論文
邊界型升壓式LED模組驅動技術之研究
Study of Boost and boundary-type LED module Drive Technology
摘要
本研究提出一具功因修正器之主動箝位返馳轉換器於LCD-TV中LED背光電路的應用。為了降低功率損耗以及穩定性考量，本研究使用主動箝位返馳式轉換器做為電源供應元件，以電流回授的脈波寬度調變方式得到穩定電壓輸出，主動箝位返馳式轉換器具有良好電壓切換性能，可有效降低切換損耗和雜訊、提高操作頻率和轉換效率，同時具有架構簡單、柔性切換等特性。輸出級採用電壓控制電流源，以運算放大器回授取得一可調光的定電流輸出驅動LED，使得每一LED電流相同，減少個別LED間輝度的差異。最後，本研究以電路擬真軟體TINA實際模擬與測試一LED背光電路模型，前級利用邊界電流模式功率因數修正電路改善輸入功率因數；後級則為主動箝位返馳式轉換器電路。模擬結果顯示，本研究所提出之LED背光電路具有良好的電壓輸出性能。
並列摘要
In the thesis, an active-clamp flyback converter with power factor corrector is applied in the LED backlight circuit for LCD-TV. In order to reduce the power consumption and the consideration of stability, an active-clamp flyback converter that can maintain the output voltage value in a constant by using fixed frequency current-mode PWM modulation is used to be the power supply. An active-clamp flyback converter with good voltage switching feature can reduce switching losses and noises effectively. Therefore, the operating frequency and the conversion efficiency can be raised. An active-clamp flyback converter features simple structure and soft switching operations. An op amplifier with voltage control is employed so that the output current is almost constant. It ensures a constant current to drive LEDs without disturbance due to the voltage source. Finally, we use the TINA Design Suite to complete the simulation of the LED backlight circuit prototype. The front-end circuit is a transition-mode (TM) PFC for achieving a unity input power factor (PF). The post-stage circuit is an active-clamp flyback converter. Simulation results show the good output voltage performance of the proposed LED backlight circuit and verify its effectiveness.