Electrolytic capacitors are often needed to provide the high-density energy storage required by ac-powered LED drivers; however, they are also well known for their short lifespans. Eliminating electrolytic capacitors in ac-dc LED driver design has become a very important target to improve LED driver technology. In this paper, a cycle-by-cycle energy buffering LED driver has been proposed to achieve electrolytic capacitor-less flicker-free operation. An energy buffering unit, with high-voltage film capacitors being the energy storage device, is introduced in the design to buffer the imbalanced energy in every switching cycle. The switching current can be controlled to meet high power factor correction requirement, while maintaining dc LED output current at the same time. Compared to previous electrolytic capacitor-less designs, this technology can reduce circulating power and, therefore, power conversion loss. A 15-W experimental prototype had been built and tested to verify the proposed LED driving method.
Bibliographical noteFunding Information:
This work was supported by theNatural Sciences and Engineering Research Council of Canada
Manuscript received January 24, 2018; revised June 13, 2018 and September 6, 2018; accepted October 10, 2018. Date of publication October 15, 2018; date of current version May 2, 2019. This work was supported by the Natural Sciences and Engineering Research Council of Canada. Recommended for publication by Associate Editor F. J. Azcondo. (Corresponding author: Yan-Fei Liu.) P. Fang was with the Department of Electrical and Computer Engineering, Queen’s University, Kingston, ON K7L 3N6, Canada. He is now with the University of Minnesota, Duluth, MN 55812 USA (e-mail:,firstname.lastname@example.org).
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- Cycle-by-cycle energy buffering
- Electrolytic capacitor-less design
- Flicker-free operation
- LED driver