Modulation Scheme for Dimming High-Brightness LED Lamps

Abstract

This paper presents a phase-controlled two-phase resonant converter as a highly flexible platform for evaluating different modulation patterns of the operating current for high-brightness light emitting diode (LED) lamps. This control flexibility arises from the wide bandwidth of the resonant converter ensuring an operation free of instabilities and flicker effects. The control parameter is the phase-shift, Ψ, between the drive signals of each inverter leg. The proposed driver is designed as a current source able to set different patterns of amplitude modulated (AM) output current to implement light dimming controls. A 120 W prototype has been built to validate the design proposal.