Energy-efficient residential lighting such as
household Light-Emitting Diode (LED) lamps with AC input require an AC/DC
converter (or driver) with large output capacitance to minimize the low
frequency LED current ripple. The energy storage capacitor used in the
conventional AC/DC LED driver is usually an electrolytic capacitor due to its
low cost and high energy density. However, the average lifetime of an
electrolytic capacitor is at least 2 to 3 times less than that of a LED device.
Hence, the potential lifetime of the LED lamp is significantly affected by the
presence of the electrolytic capacitor in the driver circuit. In this article, 2
novel isolated single-switch AC/DC high power factor LED drivers without using
any electrolytic capacitors are proposed. In the proposed circuits, the energy
storage capacitor is moved to the rectifier side, with a three-winding
transformer used to provide isolation; input power factor correction as well as
to store and provide the required energy to the output. As a result, the energy
storage capacitance is significantly reduced, which allows film capacitor to be
used to replace the conventionally used electrolytic capacitors. The circuit’s
operating principles and its characteristics are described in this paper.
Simulation and experimental results are given on a 120Vrms, 12W prototype to
confirm that a power factor of at least 0.96 is achieved.
No comments:
Post a Comment