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

Abstract

In this paper, the optimization of the power and control stages of a previously proposed topology for an off-line LED electronic driver is presented. The full system avoids the use of electrolytic capacitors at the D C link, therefore increasing the lifespan and reliability of the driver. As a consequence of having a relatively small capacitance, the D C link operates with a large Low-Frequency ( L F ) voltage ripple. This work presents a design optimization for the power and control stages of a current-fed bidirectional buck converter, operating as the LED current control stage. As this block processes only the A C power arising from the L F voltage ripple, it can increase the system efficiency against the typical two-stage solution. In the original proposal, the main drawback was the high inductor losses due to the resulting large inductor currents and large inductance value. The proposed optimization ensures an enhanced design of the inductor while keeping a constant current through the LEDs. A new optimization methodology is proposed and the theoretical results have been validated in a built prototype for a 40 W LED lamp.

Latest Developments in LED Drivers

“…The functionality of the 144 W ac-dc LED driver for street lighting applications is validated, displaying a PF >0.97, an output current ripple <2% and a maximum efficiency close to 90%. Another type of quasi-single-stage ac-dc LED driver is presented in [9]. In this case, the main concern is the elimination of the most limiting element in terms of lifespan (i.e., the electrolytic capacitor).…”

Analysis of LED Lamps’ Sensitivity to Surge Impulse

“…When estimating the MTBF/MTTF, the real factors that have a significant impact on the operating time are temperature, humidity in the surrounding of the lamp and change in voltage and current supplying LED in the lamp [9]. The fact that they have a measurable impact on the operation of lamps and the duration of their serviceability was presented in publications [9][10][11], where their selected types were tested under extreme conditions. The authors' experience shows that the declared and estimated durations of correct operation of LED lamps in many cases differ significantly from those observed in reality.…”

Dimming Techniques Focusing on the Improvement in Luminous Efficiency for High-Brightness LEDs

“…Different dimming techniques or functions employed will bring diverse concerns to their impact on a visible light flickering to a human eye and the power quality of a grid [20][21][22]. Therefore, a large number of new driver topologies have been proposed to raise the driver efficiency and power density [23][24][25][26][27]. On the other hand, many literatures focus on the research of novel dimming and current control methods that can achieve more luminosity flux generation with the least energy consumption to further meliorate the entire driving performance.…”