Study and Implementation of Integrated Power Supply for LCD TV

• Main Authors: Yu Wen Zheng, 鄭裕文
• Other Authors: Jong Chwen Wang
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/99233259628624936186

碩士 === 元智大學 === 電機工程學系 === 95 === This thesis presents the results of study and implement action to integrate two subsystems of (1) two-stage power factor correction ac-dc converter and (2) dc-ac inverter. To enhance the efficiency of low utlity-line and reduce the temperature of main components such as MOSFETs, ICs and transformers, the two-stage power factor correction subsystem bootsts up to 230 V on low utlity-line and 400 V on high utlity-line separats by a line reference voltage 150 V. This power factor correction subsystem reduces the total harmonic distortions of input current and enhances the rated power and efficiency by using the boundary-conduction-mode (BCM) operated L6561 IC of ST, this main power dc-dc converter and standby power dc-dc converter subsystem is both using the flyback topology, are used with SG6841 IC of SG and TOP 263 IC of TI. This thesis also covers the standby mode design with the resulting standby power being under 1 watt to reduce the power distortion of standby mode. The dc-ac inverter subsystem using the OZ9939 IC of O2 Micro, is the “push pull” instead of the “full bridge” topology to reduce the temperature of switches, and enhance the total efficiency. This thesis tries to use one transformer to control the lamp current equivalently with a balance choke. Then, the proposed circuit integrats the ac-dc converter and dc-ac inverter subsystems on the same PCB board for saving the materials and space, and it is tested with a 20-inches 6 lamps TV panel. According the experiment reveals the optimum efficiency of the ac-dc converter being at 83% during the voltages from 90 to 264, and the optimum efficiency of inverter is at 86% with lamp current of 6mA. The optimum total system efficiency of the integrated power supply is at 71.5%, with an above average performance.