A Novel Integrated Electronic Lighting Driver Circuit for Supplying an LED Projection Lamp with High Power Factor and Soft Switching Characteristics

Abstract

The traditional light source of projection lamps adopts a halogen lamp, which has the advantages of high brightness, but its luminous efficiency is not good and consumes energy. A light-emitting diode (LED) has the characteristics of high luminous efficiency and energy savings and can be used as a new light source for projection lamps. The conventional two-stage electronic lighting driver circuit for supplying an LED projection lamp is composed of an AC-DC converter with power factor correction (PFC) as the first stage and a DC-DC converter for providing rated lamp voltage and current as the second stage. The conventional LED projection lamp driver circuit has more circuit components, a higher cost and limited efficiency. Therefore, this paper proposes a novel electronic lighting driver circuit for supplying an LED projection lamp with PFC function, which integrates a modified stacked dual boost converter and a half-bridge LLC resonant converter into a single-stage power-conversion circuit. The inductor inside the modified stacked boost converter is designed to operate at discontinuous conduction mode (DCM) for the driver circuit achieving PFC. Wide bandgap semiconductor devices silicon carbide (SiC)-based Schottky diodes are utilized to reduce power diode losses, and soft switching is implemented in the proposed LED projector lamp driver circuit to reduce the switching losses of the power switches and thus improve circuit efficiency. This paper has completed a single-stage prototype driver circuit for an LED projection lamp with PFC function, and the prototype circuit has a high power factor (PF > 0.98), low input current total-harmonic-distortion (THD < 6%) and high efficiency (>89%) in the case of an AC input power supply with an RMS value of 110 volts, and both power switches have the characteristics of soft switching.