Tapped-inductor buck HB-LEDs AC-DC driver operating in Boundary Conduction Mode for replacement incandescent bulb lamps

It is known that High-Brightness Light-Emitting Diodes (HB-LEDs) are potential successors of incandescent bulb lamps due to its high luminous efficiency and high lifetime. To realize these advantages the HB-LED ballast must be durable and efficient. Also, for this specific application the ac-dc HB-LEDs ballast needs high-step-down ratio, high Power Factor (PF) and low-cost. This paper presents a tapped-inductor buck Power Factor Corrector (PFC) operating in Boundary Conduction Mode (BCM) design for replacement incandescent bulb lamps. This low-cost solution presents the adequate high-step-down ratio without galvanic isolation in order to produce an output voltage of about 20 V from line voltage. Also, the tapped-inductor buck PFC maintains high efficiency in comparison to other PFCs based on one stage (i.e. flyback PFC). A static analysis, distortion analysis of the input current, design procedure and an average small signal model of the ac-dc HB-LEDs driver have been carried out in this paper in order to provide an adequate design procedure. Finally, a 12 W experimental prototype was developed in order to validate the theoretical results presented.