A Nonisolated Wide-Range Resonant Converter for LED Driver Applications

In this article, a nonisolated resonant light-emitting diode (LED) driver based on the
LCLC
resonant network is presented. The adopted
LCLC
network can provide load-independent current for LED string, also, the soft switching range, and the semiconductor devices rms current can be optimized within the entire range of the input and output voltage using the
LCLC
network parameters. A single auxiliary switch is employed for regulating the output current within a wide input voltage range using pulsewidth modulation (PWM) control. In addition, the employed auxiliary switch can provide PWM dimming and open-load protection features. Detailed theoretical analysis, including the operating modes and soft switching conditions of the proposed LED driver, is presented, and the impact of the auxiliary switch snubber capacitor on the load-independent output current characteristic is analyzed. To verify the analysis and effectiveness of the proposed topology operation, a 40 W laboratory prototype with the input voltage range of 80–230 V is designed and implemented, which delivers 0.5 A current to a high-brightness light-emitting diode string.