AC-connected light emitting diode (LED) drivers experience imbalanced energy between input and output in a half-line cycle. To achieve the flicker-free operation, the imbalanced energy needs to be buffered, often by energy-dense electrolytic capacitors. However, electrolytic capacitors are also well-known for their short lifespan. These capacitors are the limiting factor of an LED drivers' lifespan. High voltage film capacitors and a buck converter have been used in the proposed LED driver to buffer the imbalanced energy. When P in > P LED , the extra energy is transferred from the ac input directly to the high voltage film capacitors. When P in < P LED , the energy is transferred from the high voltage film capacitors to the output by the buck converter. The imbalanced energy goes through two power conversion steps in the proposed LED driver, which is one time less than other comparable electrolytic capacitor-less designs, enabling a higher efficiency to be achieved. A 28 W flyback topology based experimental prototype had been built and tested to verify the proposed design.
Bibliographical noteFunding Information:
Manuscript received February 10, 2018; revised June 5, 2018 and August 17, 2018; accepted September 20, 2018. Date of publication October 8, 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 J. Lam. (Corresponding author: Yan-Fei Liu.) P. Fang was with Queen’s University, Kingston, ON K7M 3N6, Canada. He is now with the University of Minnesota, Duluth, MN 55813 USA (e-mail:, firstname.lastname@example.org).
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- AC-connected light emitting diode (LED) driver
- electrolytic capacitor-less
- energy buffering
- flicker-free operation
- high power factor