DETERMINATION OF ROAD LIGHTING AUTOMATION STRATEGIES CONSIDERING DRIVING SAFETY BASED ON VISIBILITY CONCEPT (OP38, 277-283)

Temperature dependence of LED operation is often not fully considered during the design of solid state lighting products. If temperature dependence is not carefully considered, solidstate lighting products are typically overdesigned to be too robust enough to fulfil the requirements under any possible environmental conditions. Temperature dependent nature of LEDs though, could even be a new benefit if properly considered. Overdesign means designing for the worst case that is the highest possible environmental temperature when LED efficiency/efficacy is low. With a control scheme resulting in constant emitted total luminous flux significant electrical power saving can be achieved since at lower temperatures, due to increasing efficiency/efficacy less electrical power, thus, lower forward current levels are sufficient. We present the new, so called iso-flux control scheme and its implementation in an actual smart luminaire. The actual control scheme was designed with a multi-domain LED model and the results were validated by simulation.