Design and Implementation of a Digitally-Controlled Single-Stage Flyback Converter with Power Factor Correction

• Main Authors: Cheng-hsien Chien, 簡政賢
• Other Authors: Yi-Hua Liu
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/11872421178394632794

碩士 === 國立臺灣科技大學 === 電機工程系 === 100 === High-brightness LEDs are energy-saving and cost-effective choices that enable the next generation of lighting applications. Typically, an LED driver with active PFC is implemented with two-stage topology. The first stage can achieve a near unity power factor and a low THD at universal input voltage range, while the second stage is used for the dc/dc conversion. However, two-stage topology has two independent feedback controls and a high component count, leading to an increased cost and size. In low-power lighting applications, where cost is the dominant issue, such an approach loses attractiveness. On the other hand, digital power control techniques are rapidly gaining market share as designers increasingly appreciate the advantages that the technology offers over its analog counterpart. In this thesis, the digital control technology for single-stage flyback power factor corrector (PFC) is investigated. Firstly, one analog single-stage flyback PFC circuits is built using the L6561 PWM control IC. Next, using the same power stage, two digital control algorithms using the Microchip dsPIC33FJ16GS502 digital signal controller (DSC) are developed. The developed digital control algorithms include digital voltage follower control and digital critical conduction mode control. Finally, experimental results of these three single-stage flyback PFC circuits will be provided to validate the correctness of the proposed digital control algorithms. According to the experimental results, all the three presented PFC circuits can achieve efficiency higher than 85% and power factor higher than 90.