Phase-Controlled Parallel-Series (LC_pC_s) Resonant Converter to Drive High-Brightness Power LEDs

摘要

This paper presents the analysis and design of a resonant converter suitable to drive high-brightnessrnpower LED lamps for outdoor lighting applications. The inverter stage arises from the parallelrnconnection of two class D LCpCs resonant inverters. The output stage is based on a central taprntransformer and a rectifier without electrolytic capacitor. The output current can be precisely adjusted,rnat constant switching frequency, trough the phase displacement, Ψ, of the control signals of eachrnclass D section. The dimming control follows a PWM pattern whose on-state is set by the nominalrnphase displacement Ψ and the off-state by setting Ψ at 180o where the output current is cancelled out.rnTherefore, the average lamp current is modified without necessity of extra switches. The fastrndynamics of the resonant stage ensures an operation free of instabilities and flicker effect. A 120Wrnprototype has been built to validate the design proposal.