Future Lighting Solutions created what is known as the Certified Solutions Partner (CSP) network in 2004 with the aim to accelerate the adoption of Luxeon LEDs in lighting applications.
The objective was to create a network of companies with expertise in the use of Luxeon LEDs that lighting manufacturers could tap into when designing a Luxeon-based solution. To date there are 52 selected partners from around Europe, the Americas and Asia that demonstrate expertise, skill and understanding of Luxeon-based design from the concept stage through to production. One such partner is MAL Effekt-Technik based in Germany.
In 2004, MAL undertook the challenge of creating a high-power LED swimming pool floodlight to replace existing halogen lighting. The aim was to create a module fitting the standard mounting of a 150 W halogen-based underwater floodlight with comparable or improved illumination.
They began by sizing up the competition, and analysing relevant data for the halogen model. For instance, the halogen floodlight was measured with an optical measuring bench to register the whole lighting allocation which would need to be reproduced. Additionally, the halogen reflector was optically measured and included in the data used to develop the secondary optic for the high-power LED module.
The first major challenge was to specify the electronic requirements. Since there was only a two-core wire leading to the floodlight, electronic control had to be placed within the high-power LED module itself. The maximum voltage was limited to 24 V, so MAL decided to use an external switching power supply with power factor correction, featuring an input voltage range from 100 V to 300 V and an output voltage of 24 V.
Based on the analysed optical data, MAL calculated that the required amount of lumen output equated to 24 Luxeon III LEDs. Ideally, the designer would have preferred to use more LEDs but, as this was a retro-fit assignment, space was limited. Using Luxeon III Stars various prototypes were built and tested, which were used to develop the secondary optic and to test the electronic control equipment.
After final mechanical configuration of the LEDs, the PCB was developed. MAL opted for metal core printed circuit board (MCPCB) material by Bergquist as this offered the heat conductance required to efficiently drive the high-power LEDs.
As MAL strongly believe in the importance of efficient and intelligent thermal management, an 8-bit microcontroller was integrated into the module to control temperature, supply constant current via a switching regulator and to implement soft-start. Both the microcontroller and the switching regulator were to be included on the PCB, which added to the demand on the limited amount of available board space.
The biggest issue, however, was how to remove heat from high-power LEDs housed in a stainless steel floodlight case. Stainless steel has a bad heat conductance value, so MAL designed an aluminium heat-sink which stored enough heat to allow dissipation through the stainless steel case and into the surrounding water. To achieve this, various calculations, simulations and prototypes were required, with a slug temperature of 45°C eventually being achieved at a water temperature of 30°C.
Since the completion of the project, MAL has built and sold hundreds of the underwater floodlights, in single colours as well as RGB. Also, their adoption of high-power LED technology has not stopped and today the company produces underwater floodlights with 27 Luxeon K2 LEDs and an input voltage of 12 V.
For more information visit www.futurelightingsolutions.com or contact Future Electronics, +27 (0)21 421 8292, kenneth.naidoo@futureelectronics.com, www.futureelectronics.com
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