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.