High-Efficient Resonant Converter for LED Driver Applications

In this study, a boost-type Pulse Width Modulation (PWM)-resonant converter is proposed for LED driver applications. Thanks to resonance operation, the converter works with zero current switching for most of the switching instants. Thus, high efficiency can be obtained more easily. It utilizes capacitive energy transfer and offers a reduction in the required inductor size. This leads to converter designs with high power density. The operation principle of the PWM-resonant converter is presented by performing its static analysis and explaining the design constraints. The mathematical proof for determining key design parameters is also given before being verified experimentally, together with other findings. The small-signal ac model of the converter is derived, and a type II compensator is designed to achieve closed-loop current control for LED dimming applications. A 200W PWM-resonant converter prototype was built to evaluate the converter performance under steady-state and transient conditions. Experimental and simulation results are provided to verify the theoretical analysis.