Measurements of thermal resistance of power LEDs

Abstract

Purpose -The purpose of this paper is to present a new method of measuring thermal resistance of power light-emitting diodes (LEDs). Properties of power LEDs strongly depend on their internal temperature. The value of this temperature depends on the cooling conditions characterized by thermal resistance. Design/methodology/approach -The new method of measuring the value of this parameter belongs to the group of electric methods. In this method, the problem of estimating the value of electrical power converted into light is solved. By comparing the values of the case temperature obtained for the LED operating in the forward mode and the reverse-breakdown mode, the thermal power is estimated. On the basis of the measured value of the thermally sensitive parameter (the LED forward voltage) and the estimated value of the thermal power, thermal resistance is calculated. Findings -The elaborated method was used to measure thermal resistance of the selected types of power LEDs operating at different cooling conditions. The correctness of the elaborated measurement method was proved by comparing the results of measurements obtained with the use of the new method and the infrared method. Research limitations/implications -On the basis of the obtained results of measurements and the catalog data of the tested diodes, the dependence of the measurement error of thermal resistance of the LED on its luminous efficiency is discussed. Originality/value -The new measurement method is easy to use and more accurate than the classical method of thermal resistance measurement of the diode.

The Analysis Of Accuracy Of Selected Methods Of Measuring The Thermal Resistance Of IGBTs

“…The dc methods are especially convenient to use [17,29], and − contrary to the classical impulse methods [14,16,18] − they do not demand switching the power supplies of the investigated device. The accuracy of the thermal resistance measurements with electrical methods depends mostly on choosing an appropriate thermally sensitive parameter.…”

Modelling mutual thermal coupling in LED modules

“…The manner of estimating the value of electric and optical parameters existing in the model of the power LED is described in the paper by Górecki (2015), whereas the manner of the measurement of transient thermal impedances of the power LEDs is described in the paper by Górecki (2014). Furthermore, the manner of the measurement of mutual transient thermal impedance between power LEDs is presented by Ptak (2014a, 2014b).…”

The influence of the mounting manner of the power LEDs on its thermal and optical parameters

“…As the great advantage of solid-state light sources seems to be long life time [4,12], the essential problem is to remove heat generated in the considered devices [13,14]. In papers [6,7,15,16] the strong influence of self-heating phenomena and mutual thermal interactions on the course of characteristics of power LEDs are shown.…”

“…power LEDs, in the steady-state are characterized by thermal resistance R th . The problem of measurement of this parameter is focused on among other in papers [15,16,18,19]. As semiconductor devices operate in dynamic conditions, their thermal properties are described by the transient thermal impedance Z th (t) [20,21].…”