A Novel Step-Down Single-Stage PFC Flyback Converter with Low Output Voltage Ripple and Leakage Energy Recovery

• Main Authors: Yan -Jhe Shih, 施晏哲
• Other Authors: Yie-Tone Chen
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/tqyt6g

碩士 === 國立雲林科技大學 === 電機工程系 === 107 === A novel step-down single-stage PFC flyback converter with low output voltage ripple and leakage energy recovery is proposed in this thesis. The proposed circuit is designed to reduce the output voltage ripple of the conventional single-stage flyback power factor correction circuit and achieve high power factor simultaneously. Two sets of auxiliary windings and capacitors are added to the conventional single-stage flyback power factor corrector. One set of auxiliary winding and capacitor provides power to the output when the input voltage is low, so that the output voltage ripple can be reduced. The other set of auxiliary winding and capacitor improves the lower power factor caused by adding the above set of auxiliary winding and capacitor. Since the second auxiliary capacitor is in series with the input side, it can avoid a serious distortion of the input current and make a significant improvement in the power factor. The proposed circuit will achieve a reduction in the output voltage ripple and simultaneously keep a high power factor. In addition, this paper will also discuss two snubber methods - lossless snubber and RCD snubber, and compare the related results with the two methods. The proposed circuit is operated in the boundary conduction mode (BCM). How to reduce the output voltage ripple and achieve a high power factor with the additional auxiliary circuits will be explained in detail in this thesis. A design example is given to a flyback converter with the load of 24V and 48W for wide input voltage range of 85 Vrms-265Vrms. Finally, the simulation and experimental results are used to verify the proposed circuit can achieve the low output voltage ripple and high power factor at the same time. Keywords：single-stage, step-down flyback converter, output voltage ripple reduction, high power factor, leakage energy recovery