AC–DC Flyback Dimmable LED Driver with Low-Frequency Current Ripple Reduced and Power Dissipation in BJT Linearly Proportional to LED Current

Yeu-Torng Yau; Kuo-Ing Hwu; Kun-Jie Liu

doi:10.3390/en13164270

Energies (Aug 2020)

AC–DC Flyback Dimmable LED Driver with Low-Frequency Current Ripple Reduced and Power Dissipation in BJT Linearly Proportional to LED Current

Yeu-Torng Yau,
Kuo-Ing Hwu,
Kun-Jie Liu

Affiliations

Yeu-Torng Yau: Department of Ph.D. Program, Prospective Technology of Electrical Engineering and Computer Science, and Department of Electrical Engineering, National Chin-Yi University of Technology, No.57, Section 2, Zhongshan Rd., Taiping District, Taichung 41170, Taiwan
Kuo-Ing Hwu: Department of Electrical Engineering, National Taipei University of Technology, 1, Section 3, Zhongxiao E. Rd., Taipei 10608, Taiwan
Kun-Jie Liu: Chicony Power Technology Co., Ltd., Sanchong, New Taipei City 24158, Taiwan

DOI: https://doi.org/10.3390/en13164270
Journal volume & issue: Vol. 13, no. 16
p. 4270

Abstract

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In this paper, a dimmable light-emitting diode (LED) driver, along with the low-frequency current ripple decreased and the bipolar junction transistor (BJT) power dissipation reduced, is developed. This driver is designed based on a single-stage flyback converter. On the one hand, the low-frequency output current ripple reduction is based on the physical behavior of the linear current regulator. On the other hand, when the voltage across the LED string is decreased/increased due to dimming or temperature, the output voltage of the flyback converter will be automatically regulated down/up, thereby making the power dissipation in the BJT linearly proportional to the LED current. By doing so, not only the power loss in the linear current regulator will be decreased as the LED current is decreased or the LED temperature rises, but also the output current ripple can be reduced. Furthermore, the corresponding power factor (PF) is almost not changed, and the total harmonic distortion (THD) is improved slightly. In addition, the LED dimming is based on voltage division. Eventually, a 30 W LED driver, with an input voltage range from 85 to 295 Vrms and with 24 LEDs in series used as a load, is developed, and accordingly, the feasibility of the proposed LED driver is validated by experimental results.

Published in Energies

ISSN: 1996-1073 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Technology
Website: http://www.mdpi.com/journal/energies

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