Design and Implementation of a Digitally-Controlled LLC Resonant Converter

• Main Authors: HAO-WEI CHIN, 金浩瑋
• Other Authors: Yi-Hua Liu
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/28763104311834652621

碩士 === 國立臺灣科技大學 === 電機工程系 === 100 === Red, green and blue (RGB) light emitting diodes (LEDs) for backlighting are found in high-end display units as well as next-generation consumer grade displays. The advantages of RGB LEDs include wide color gamut, tunable white point, higher luminance efficacy, and high dimming ratio. Because RGB LEDs have different forward voltages for the red, green, and blue LEDs, dynamic bus voltage regulation (DBVR) can be applied to optimize the power stage design. In this thesis, a RGB LED backlight driving system is proposed. The proposed system consists of a power factor correction pre-stage, a digitally-controlled LLC resonant converter and a flyback converter auxiliary power supply. The LLC resonant topology allows for zero voltage switching (ZVS) of the main switches thereby dramatically lowering switching losses and boosting efficiency. The adjustable output voltage of the presented LLC resonant converter is adjusted by a digital controller so that RGB LED maintains the desired string current; this will improve the efficiency of the driving system. Detailed description about the hardware and firmware parts of the proposed system is presented. Finally, experimental results are presented to validate the correctness of the proposed system. According to the experimental results, the presented system can adjust the output voltage of the LLC resonant converter according to the requirements of the RGB LED string.