Abstract

Energy-efficient residential lighting such as household light-emitting diode (LED) lamps with AC input require electrolytic capacitor as the energy storage dc-link capacitor in the driver circuit to balance the energy between the input and output power and reduce the low frequency LED current ripple. The average lifetime of an electrolytic capacitor is at least 2–3 times less than that of an LED lamp which affects the potential lifetime of the overall circuit. To increase the lifetime of the LED lighting system, an offline LED driver that does not use any electrolytic capacitors or complicated control circuits to minimize the low-frequency (i.e., 100 or 120 Hz) output ripple is presented here. The proposed single switch circuit reduces the energy storage capacitance to a few microfarads range, so that film capacitor can be used to replace the unreliable electrolytic capacitor. The circuit operating principles and its theoretical analysis are studied and simulation results are given on a 9-W LED lamp to highlight the merits of the proposed circuit.