Abstract
This paper concerns the problem of modelling electrical, thermal and optical properties of multi-colour power light-emitting diodes (LEDs) situated on a common PCB (Printed Circuit Board). A new form of electro-thermo-optical model of such power LEDs is proposed in the form of a subcircuit for SPICE (Simulation Program with Integrated Circuits Emphasis). With the use of this model, the currents and voltages of the considered devices, their junction temperature and selected radiometric parameters can be calculated, taking into account self-heating phenomena in each LED and mutual thermal couplings between each pair of the considered devices. The form of the formulated model is described, and a manner of parameter estimation is also proposed. The correctness and usefulness of the proposed model are verified experimentally for six power LEDs emitting light of different colours and mounted on an experimental PCB prepared by the producer of the investigated devices. Verification was performed for the investigated diodes operating alone and together. Good agreement between the results of measurements and computations was obtained. It was also proved that the main thermal and optical parameters of the investigated LEDs depend on a dominant wavelength of the emitted light.
Highlights
Light-emitting diodes (LEDs) are the most important components of solid-state lighting sources commonly used in the lighting technique [1,2,3,4]
This paper presents the manner of modelling the electrical, optical and thermal properties of colour and white power LEDs situated on a common PCB
A very simple manner of computing the device junction temperature of each diode is proposed. It is based on the concept of self- and transfer electrical transient thermal impedances, which makes it possible to perform fast and accurate computations and take into account the differences in the junction temperatures of the power LEDs situated on a common PCB
Summary
Light-emitting diodes (LEDs) are the most important components of solid-state lighting sources commonly used in the lighting technique [1,2,3,4]. The thermal properties of the modelled diode are characterised by the use of one device junction temperature, the value of which depends on ambient temperature and the dissipated heating power This power is equal to the difference between the electrical power supplying this device and the optical power characterising the emitted light. The new model takes into account simultaneously self-heating in each LED and mutual thermal coupling between each pair of the considered devices In this model, a very simple manner of computing the device junction temperature of each diode is proposed. A very simple manner of computing the device junction temperature of each diode is proposed It is based on the concept of self- and transfer electrical transient thermal impedances, which makes it possible to perform fast and accurate computations and take into account the differences in the junction temperatures of the power LEDs situated on a common PCB. The three above-mentioned components of the new model are described
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