ISBN 9783843931953

978-3-8439-3195-3, Reihe Elektrotechnik

Stefan Dietrich
Low-Effort Multichannel LED Driver Architecture for Tunable White Luminaires

172 Seiten, Dissertation Rheinisch-Westfälische Technische Hochschule Aachen (2017), Hardcover, A5

Zusammenfassung / Abstract

Advances in semiconductor technology introduced modern solid-state lighting (SSL) to common lamp production with a rapidly growing market share in all conceivable applications. Unfortunately, the growing market share of SSL must be steered and controlled by governments regulatory interventions. The reason for these interventions is the very low price for the poor energy efficient incandescent lamps, since the establishment of more energy efficient technologies is economically hard to realize. In Europe, the well-known ecodesign directive 2009/125/EC and the directive 2009/244/EC severely affect the lighting market. The directives state that the preferred technology to be supported is SSL since it offers an energy efficiency “class A”. Despite all efforts to force the development of energy efficient lamps, the question of cost of products for the consumer remain vague. A major disadvantage of SSL is that the required electronic components must be operated at grid-based voltage supply.

In order to minimize the cost of SSL based lamps, passive circuits are commonly used. As a result, LED light bulbs with fixed color temperatures of typically more than 5000K for daylight white lamps, 3300-5000K for neutral white, and below 3300K for warm white lamps are available. Modern products to generate so-called tunable white light are outnumbered and are still quite expensive. The costs of these “intelligent” lamps are mostly dependent on their implemented active system-on-a-chip driver circuits. The generation of tunable white light calls for multiple LED strings with different colors and color mixing. Consequently, the complexity and bill of materials (BOM) is high.

The main goal of this work is the development and implementation of a low-effort, with respect to a low external component count, integrated multichannel LED driver topology for tunable white luminaires. The multichannel driver has to maintain high reliability and especially has to support low BOM, which state-of-the-art drivers do not offer. Not only cost is negatively affected by the use of multiple external components, but also the form factor. A higher number of external components requires more expensive PCBs and may not fit into existing lamp fixtures. To solve this problem, a sophisticated monolithic integration of the LED driver is required. The system integration should also lead to high system efficiency, which is essential to keep up with the legislative-driven energy saving guidelines.