Title :
High-Efficiency DC–DC Converter With Twin Bus for Dimmable LED Lighting
Author :
Yu, Wensong ; Lai, Jih-Sheng ; Ma, Hongbo ; Zheng, Cong
Author_Institution :
Bradley Dept. of Electr. & Comput. Eng., Virginia Polytech. Inst. & State Univ., Blacksburg, VA, USA
Abstract :
An improved twin-bus converter using n + 1 active switches is proposed for the n-string LEDs to be dimmable from true zero to the rated current level. The n-switches that perform the current-loop regulation can operate at very high frequency because of significantly reduced voltage stresses, while achieving high efficiency over a wide load range. The dimming switch, however, can operate at a low frequency to ensure high-efficiency operation without light flicker. The detailed power stage operating principle and control scheme of the individual string current for the presented converter are described. Experimental results of a 3-string 50-W LED driver hardware prototype show that the independent string current can be regulated from zero to the desired 350 mA for dimming control. A peak efficiency of 98.3% was achieved with 1.08-MHz switching frequency.
Keywords :
DC-DC power convertors; LED lamps; electric current control; lighting control; LED driver hardware prototype; active switches; current 350 mA; current-loop regulation; dimmable LED lighting; dimming control; dimming switch; frequency 1.08 MHz; high-efficiency DC-DC Converter; n-switches; power 50 W; twin-bus converter; voltage stresses; Converters; Light emitting diodes; Lighting; Pulse width modulation; Regulators; Stress; Switches; Asymetric multiple level converter; dimmable LED drive; high efficiency; light-emitting diode (LED); off-line LED lighting; three-level converter; two-input buck.;
Journal_Title :
Power Electronics, IEEE Transactions on
DOI :
10.1109/TPEL.2011.2104368