Isolated PFC Pre-Regulator for LED Lamps

The efficiency and lifetime of light-emitting-diode (LED) lamps are approaching and exceeding that of fluorescent lamps. LED light sources are finding more applications than conventional light bulbs due to their compactness, lower heat dissipation, real-time color changing capability and most importantly, long life which is much longer life than that of conventional offline power converters. Conventional power converters normally use high voltage electrolytic capacitors as energy storage element which could have the shortest lifetime when compared to other components of the LED lighting system. In this paper, a new isolated PFC power pre-regulator is proposed. The pre-regulator allows the charge storage capacitor to be positioned on the secondary side of the isolation transformer. Longer lifetime low voltage and high capacitance value capacitors can therefore be used to extend the overall lifetime of the LED lighting system. Steady-state state-space averaging analysis is preformed for designing the converter. A prototype converter is built to verify performance of the proposed PFC LED preregulator.