A novel pulse current driving; High power factor LED driver without electrolytic capacitors

Light emitting diode (LED) drivers with AC-input (50 or 60Hz) usually require an electrolytic capacitor as the DC link capacitor to: (1) balance the energy between the input and output power, and (2) to minimize the low-frequency output ripple across the LEDs. The lifetime of this capacitor, however, is much shorter than that of a LED. A new pulse current driving LED driver that does not require any electrolytic capacitors or complicated control circuits to minimize the low-frequency output ripple is proposed in this paper for AC-input application. The proposed circuit is simple and a small size film capacitor is used to replace the energy storage electrolytic capacitor. A pulsed high frequency triangular current is used to drive the LEDs in the proposed circuit to improve the stability of the LED luminous intensity. Simulation and experimental results are given on an 8W LED lamp to highlight the merits of the proposed circuit.