LED drivers Phosphor technology - Beriled

Driving LEDs –
A Real Challenge
> Arno Grabher-Meyer, LED professional
Selecting the right design to drive a LED system is easy, isn’t it?
– Choose a LED, take a voltage source and limit current with a
resistor. For several years it was done in that way. Can that be so
wrong?
Yet modern, efficient and high quality LED systems are far more complex
and challenging than former applications, when LEDs were mostly used
as indicator lights. We have to imagine, that there are a lot of different
applications with many conceptual paths. LEDs can be used as
replacement for low voltage halogen light or high voltage halogen light,
but also to design revolutionary new luminaries for office lighting or
residential lighting, a wall washer or floodlight, etc.
For the electronic designer the differentiation starts with the chosen
LEDs for the particular application. To achieve an optimum result
individual solutions are necessary, e.g. arrays of mid power LEDs require
other electronics than a single or a few high power LEDs. A lot of
additional questions have to be answered before the design process can
be started:
Will the LEDs be driven in series or in parallel? Is the design based on
LEDs of the similar colour and type, or is it a multicolour design for
adaptation of CCT, CRI or colour effects? What are the real requirements
for the light quality, the dimming range, the colour stability over time,
the light output? How to take in account degradation over time or
thermal issues?
Besides application specific questions there are some really basic
problems that engineers are confronted with. These are the real
challenges that are partly new in the field of lighting electronics:
Improve electrical efficiency
At the International „Workshop on Status, Prospects and Strategies for
LEDs in General Lighting 2007” Dr. Geoff Archenhold from SSLRC stated
“A LED fixture is more than just a LED, it’s a system!” Improvement of
driver efficiency from 80% to 88% results in a 5% increase of system
efficacy. Considering the struggle of the European Community for CO2
reduction this 5% improvement is not negligible.
There are numerous contradictions that can hinder or constrict
optimization of efficiency:
•
•
A big difference between Mains voltage and secondary output
voltage.
Needs for a specific driving mode, because light quality would
suffer.
Copyright © 2007 Luger Research & LED professional. All rights reserved.
DRIVER MODULE MANUFACTURERS
AbstractAvr http://www.abstractavr.com
Acro Engineering Inc. http://acro-powers.com
Advance http://www.advancetransformer.com
Aurora Ltd http://www.aurora.eu.com
CML Innovative Technologies http://www.cml-it.com
Erea nv http://www.erea.be
Insta Elektro GmbH http://www.insta.de
L.C. Relco S.p.A http://www.relco.it
Lightech Electronic Industries http://www.lightech.co.il
Lumotech Holland BV http://www.lumotech.com
LEDdynamics http://www.leddynamics.com
Magtech Industries Corp. http://www.magtechind.com
Mean Well Enterprises Co. http://www.meanwell.com
Nobilé AG http://www.nobile.de
OSRAM GmbH http://www.osram.de
Paulmann http://www.paulmann.de
Permlight Corporation http://www.permlight.com
Power Vector http://www.powervector.com
Prism Audio Ltd http://www.prismaudio.co.uk
Tridonic.Atco http://www.tridonicatco.com
www.led-professional.com LED professional Review | June 2007 | page 14