An AC–DC LED Driver With a Two-Parallel Inverted Buck Topology for Reducing the Light Flicker in Lighting Applications to Low-Risk Levels

Abstract

Abstract-This paper presents an ac-dc LED driver that consists of two parallel inverted buck converters. To buffer the twice-line-frequency energy, one inverted buck converter (also known as a floating buck converter) conveys energy to a storage capacitor, simultaneously performing the power factor correction (PFC). The other inverted buck converter regulates the LED current to maintain a constant brightness in the LEDs for reducing light flicker to low-risk levels. The proposed architecture reduces the voltage stress and the size of the storage capacitor, enabling the use of a film capacitor instead of an electrolytic capacitor. Considering the power factor and the flicker standards, a design procedure to achieve a high power factor, while minimizing the storage capacitance and the LED current ripple, is presented. A prototype of the proposed LED driver has been implemented with an on-chip controller IC fabricated in a 0.35 μm CMOS process and its functionality and performance have been verified experimentally. It demonstrates a power factor of 0.94 and a peak power efficiency of 85.4% with an LED current ripple of 6.5%, while delivering 15 W to the LEDs.

A Review on Flicker-Free AC–DC LED Drivers for Single-Phase and Three-Phase AC Power Grids

“…Several solutions for retrofit LED lamps have been proposed based on using non-isolated buck converters either as a single-stage or quasi-single-stage [54]- [59], [129], see Fig. 10 (a), isolated converters from the buck family [46], [60], using an LFR as the limiting resistor rendering an AICS [84], as depicted in Fig.…”

“…Active: single-stage -< 25 W [46], [51], [52], [54]- [59], [76]- [84], [107], [195] [195] 70-92 10-30…”

“…Yes. [51], [52], [55], [56], [76], [77], [79], [81], [83], [84], [107] -Analog: [51], [52], [54]- [59], [76]- [84], [107], [195] -Digital: [46] Yes.…”

A three‐leg resonant converter for two output LED lighting application with independent control

“…With the recent developments in lighting industry, light emitting diodes (LEDs) have become more popular and more accessible to general public over conventional sources. [9][10][11][12][13][14] And also, DC operated driver circuits have been proposed for LED applications to enhance dc power distribution in lighting industry. [1][2][3] At present, LEDs have entered in almost all lighting applications like signal lighting, street lighting, indoor lighting, transportation, liquid crystal display (LCD) backlighting, architectural lighting, and parking lighting.…”

“…7,8 As LEDs are operated from dc sources, good number of ac-dc LED driver topologies have been proposed to meet the essential objectives like power factor correction (PFC) and elimination of electrolytic capacitor to improve reliability and dimming features. [9][10][11][12][13][14] And also, DC operated driver circuits have been proposed for LED applications to enhance dc power distribution in lighting industry. [15][16][17][18][19][20][21][22] LED lighting applications need efficient light output, independent current regulation, and illumination control to reduce energy expenses.…”