Integrated Off-Line Ballast for High Brightness LEDs with Dimming Capability

Abstract

This paper presents an off-line integrated full ballast to supply a 35W assembly of Power LEDs. The proposed solution integrates an input PFC stage (a flyback converter operating in DCM) and a DC-DC output converter (a buck converter) into a single switch power stage, operating with peak current control. As it will be shown, this control scheme maintains the current through the load constant, regardless of the instantaneous value of the DC link voltage. This issue allows the use of a small capacitor for the DC link, which enhances the overall system reliability. The complete ballast has full dimming capability, and all the analysis and design steps are presented, thus ensuring the fulfilling of the existing regulations. The novelty of the final solution comes from the simplicity and robustness of the control scheme in an integrated compact single-switch power stage. A final prototype of the ballast has been built and tested, and experimental results are shown in the last part of the paper. Finally, conclusions and future developments are shown

Implementation of an HB-LED driver with PFC and output power control

“…Además de lo anterior, para disminuir la potencia entregada a la carga mediante esta técnica se debe recortar la forma de onda de la corriente de entrada, aumentando significativamente el THDi [20]. En [21] se presenta un método de PFC con función de atenuación basado en Modulación de Amplitud (Amplitude Modulation: AM) donde se concluye que esta forma de modulación presenta menor deterioro al factor de potencia que métodos de PWM, no obstante, la técnica AM presenta una distorsión significativa en la corriente de entrada cuando la potencia entregada a la carga es relativamente alta. En este trabajo se propone un driver para HB-LEDs que incorpora la función de atenuación de luz además de mantener un alto factor de potencia.…”

Optimization of a Series Converter for Low-Frequency Ripple Cancellation of an LED Driver

“…In order to achieve this goal, electrolytic capacitors must be discarded. Therefore, researchers have come up with novel control strategies [16][17][18][19] as well as optimized topologies [6,13,[20][21][22][23][24][25][26][27][28][29][30][31][32][33] that imply smaller capacitances in the DC link, to overcome this issue.…”