Method for in-situ power LEDs´ junction temperature measurements

In this work investigations are connected with development of method of LEDs´ junctions´ temperatures estimation at real operating conditions. Direct junction temperature determination is not possible and alternative methods have to be developed. Suitable, cheap and reliable method for direct estimation of LEDs´ junction temperatures during operating of lighting equipment is proposed. It is realized by employing the temperature dependence of LEDs´ forward voltage drop. Two different types of LEDs have been investigated at various ambient conditions (air temperatures from 20°C to 45°C) and different current values through LEDs - from 350 mA to 600 mA. Recommendations concerning calibrations, calculations and junctions´ temperatures evaluations are presented. Developed method allows achieving of reliable results “in situ” for thermal performance of LEDs using non expensive experimental equipment.