Off-line soft-switched LED driver based on an integrated bridgeless boost - half-bridge converter

This paper proposes an off-line single-stage LED driver based on a novel approach to reduce low-frequency ripple in light-emitting diode (LED) arrays supplied from mains, while assuring high input power factor. The proposal employs a series resonant DC-DC converter integrated into a bridgeless boost power factor correction (PFC) stage. The resonant stage works to reduce the low-frequency ripple transmitted from the output of the PFC stage to the LEDs with only small power losses. This solution achieves three main goals: (i) reduction of the bulk capacitance used at the DC bus, allowing for the use of long-life film capacitors, and (ii) increase of the overall efficiency of the LED driver owing to the low switching and conduction losses in the shared switching network, and (iii) assuring high input power factor. Experimental results of a driver without electrolytic capacitors for a 100 W street lighting LED luminaire are presented, showing overall efficiency in excess of 95%, input power factor of 0.98 and line current harmonic content in compliance with the IEC 61000-3-2 standard requirements.