Wide voltage gain isolated LCC resonant converters for LED driver applications

Abstract

This article proposes an isolated high‐efficiency resonant LED driver with wide‐input voltage range. The proposed converter is developed by integrating LCC resonant converter and buck‐boost converter. In this topology, the LCC network provides many features including the integration of buck‐boost filter inductor and the transformer magnetizing inductance. In addition, the LCC network provides zero voltage switching (ZVS) operation of the main switches and zero current switching (ZCS) operation of the rectifier diodes over a wide variation of duty cycle operation. Also, load‐independent output current characteristic with improved efficiency is obtained at the resonant frequency operation which is well‐suited for LED applications. Other topology variations of the proposed converter generating step‐up and step‐down voltage gains are introduced for applications with different input voltage ranges. To validate the theoretical analysis and LED driver operation, a 50 W laboratory prototype of the proposed LED driver is implemented for the wide input voltage of 18–40 V to deliver 500 mA output current to a string of 1–30 LEDs, which corresponds to an output voltage range of 3.3–100 V.