Tapped-inductor buck HB-LED ac-dc driver operating in boundary conduction mode for replacing incandescent bulb lamps

Abstract

High-brightness light-emitting diodes (HB-LEDs) are recognized as being potential successors of incandescent bulb lamps due to their high luminous efficiency and long lifespan. To achieve these advantages, HB-LED ballast must be durable and efficient. Furthermore, for this specific application, ac-dc HB-LED ballast requires a high-step-down ratio, high power factor and low cost. This paper presents a tapped-inductor buck power factor corrector (PFC) operating in boundary conduction mode design for replacing incandescent bulb lamps. This low-cost solution presents a suitable high-step-down ratio without galvanic isolation in order to produce an output voltage of about 20 V from line voltage. In addition, the tapped-inductor buck PFC maintains high efficiency in comparison to other one stage solutions widely used to design low-cost ac-dc HB-LED drivers (e.g., flyback PFCs). Static analysis, input current distortion analysis, and an average small signal model of the tapped-inductor buck PFC have been implemented in this paper both to check the validity of the proposed solution and to provide a suitable design procedure of the ac-dc HB-LED driver. Finally, a 12-W experimental prototype was developed to validate the theoretical results presented