Investigations of Mutual Thermal Couplings in Selected Lighting Sources With Power LEDs

This article presents the results of investigations of thermal parameters characterizing self-heating and mutual thermal couplings in selected LED lighting sources. Three types of such sources are considered. They are characterized by different dimensions and different mounting manners. The tested devices are described and the applied measurement method is introduced. Then, the presented results of measurements are discussed. The parameters describing self and transfer transient thermal impedances of power LEDs contained in the considered lighting sources are compared. In particular, the spectra of thermal time constants and structure functions characterizing the tested devices are determined using the original ESTYM software and the standard T3STer MASTER software. Both mentioned software packages give similar results. Transfer transient thermal impedance is delayed in relation to self-transient thermal impedance. It is shown that transfer transient thermal impedance decreases with an increase in the distance between the coupled LEDs and with the improvement of the cooling efficiency of the LED module.