The lighting industry has reached very important advancements in recent years from incandescent lamp of Thomas Elva Edison to high power lightemitting Diodes (HP-LEDs, LEDs). Now, we have two of missions for lighting experts which are the elevation and improvement of the quality of LEDs. The converting process from electrical power into the radiation has at the moment an optical efficiency of about 30-35% and has an attached relationship with the heating process (about 65%-70% total energy of a LED). Therefore if we can handle some well-defined properties of the heating process clearly, we can control the lighting process in an optimal way. Up to now, the temperature of a LED-unit has been made by a sensor positioned either on the electrical printing board or near to the LED. But the most important information is the real temperature of the pn-junction of the LED-chip. This paper has compared between cooling and heating method from both direct and indirect modes. The result shows that, the cooling method is enough good for the typical blue LED type. The method also helps building a full thermal property including static and dynamic mode for the typical blue LED type and in these specific conditions. In other special conditions and for specific demands, equivalent resistance Rth and capacitance Cth can be identified and separated into many specific values by the structure function method like or in frequency domain by identification toolbox of Matlab (Version 2009). The cooling method can be performed automatically giving better results in wider areas for other LED types.
Accurate measurement of the pn-junction temperature of HP-LEDs - Methods and results
Genaue Messung der Temepratur am pn-Übergang von Hochleistungs-LED - Verfahren und Ergebnisse
2011
19 Seiten, 13 Bilder, 4 Tabellen, 10 Quellen
Conference paper
English
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