Controlling light digitally

Dc/dc converters and MicroTCA power modules aid the expansion of LED lighting everywhere

BY PATRICK LeFEVRE
Ericsson Power Modules
Stockholm, Sweden
http://www.ericsson.com/powermodules

Recent research and developments in the board-mounted power supply industry — which is normally not too involved in lighting — have proven that digital power and power management could significantly improve the performance and power consumption of modern power supplies. Indeed, the recently released MicroTCA power module from Ericsson Power Modules deploys an embedded digitally controlled dc/dc converter, this being the first commercial application for such technology.

Dc/dc converters and MicroTCA power modules could seem to be miles away from lighting, but research aiming to improve manufacturing costs and efficiency of LED-based lighting equipment could soon link the two technologies.

Digital control in systems that power lighting makes it possible to tightly control many different parameters during the life cycle, adjusting the energy to exactly meet the lighting demand, depending on circumstances, environmental and/or local requirements. LED lighting for today’s needs has been deployed for specific usage. For example, in May 2008, Advanced Lighting Systems, a Nexxus lighting company, completed the lighting for the Norbert F. Beckey bridge in Muscatine, Iowa, that stretches from Iowa to Illinois across the Mississippi River. ( http://www.nexxuslighting.com/news/pressReleases/news_052008.php).

The commercial development of these LED matrices opens up ever increasing possibilities for such technology. Light makers, electric power companies, and researchers are working in close collaboration to explore additional opportunities offered by LEDs to achieve energy efficiency in lighting. For example, in late 2007, Duke Energy announced a collaboration with Cree in an evaluation project using LEDs for widespread commercial purposes (http://www.ledworkplace.org/press1.htm). Major cities also are considering LED lighting as an alternative to conventional light bulbs, and programs such as Led City reflect the new possibilities offered to communities to deploy LED lighting in a large scale (http://www.ledcity.org/).

LED lighting is seen as an efficient alternative to conventional lights. However, it requires power supplies that are very efficient. There is no point in using efficient LED lighting systems if the power supply performs poorly with respect to efficiency.

Using digital power in the dc/dc or ac/dc conversion stage brings the benefits of high-efficiency power conversion, even when LEDs are operated at low brightness, resulting in lower power demand (for example, when light panels compensate for low-daylight conditions in the morning and evening). The power system must adjust power conversion to guarantee the highest efficiency, whatever the load requires.

Fig. 1. Digital power control in the dc/dc conversion stage greatly benefits LED operation with high efficiency even at low brightness.

Digitally controlling the energy delivered to the load at the light panel is one of the benefits of digital power. For example, digital power makes it possible for the energy management supervisor to monitor via a communication interface, the status of lighting at any time and point of operation, resulting in an optimization of energy consumed.

Combining the latest developments in LEDs with efficient, digitally controlled power systems is the only solution to guarantee from line to user, that perfect lighting is delivered while it reduces the carbon footprint. There is no doubt that digital power and power management will make lighting more efficient by reducing the overall energy consumed and will preserve global energy resources. ■