Degradation of LED parameters during operation Brief review of currently used models and measuring methods

Pavelka, Tomas; Ptacek, Michal

doi:10.1109/epe.2015.7161147

Cited by 4 publications

(3 citation statements)

References 20 publications

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“…Many papers describe different scientific problems connected with the manufacturing, testing, modelling and technical applications of power LEDs [5][6][7][8]. In the last 10 years, the maximum value of the emitted luminous flux and the value of luminous efficiency have visibly increased [3,9,10]. Additionally, the price of power LEDs keeps decreasing every year.…”

Section: Introductionmentioning

confidence: 99%

Compact Modelling of Electrical, Optical and Thermal Properties of Multi-Colour Power LEDs Operating on a Common PCB

Górecki

Ptak

2021

Energies

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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.

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Section: Introductionmentioning

confidence: 99%

Compact Modelling of Electrical, Optical and Thermal Properties of Multi-Colour Power LEDs Operating on a Common PCB

Górecki

Ptak

2021

Energies

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“…According to research focused on thermal management of LEDs with different attach materials [2] this parameter seems to be almost constant in common temperature range of heatsink (20 °C -90 °C). There are also other options, how the junction temperature can be determined, more or less accurate [3], but study of junction temperature determination is not an issue of this paper.…”

Section: Temperaturementioning

confidence: 99%

“…White LEDs based on using of blue LED with phosphor coating are depending also on change of dominant peak ratio that determines chromaticity temperature and other qualitative parameters. Determining the factors that affect this ratio is complex issue, because each factor is based on different physical process in LEDchange on junction level, change of phosphor coating, change of electrical parameters of metal contacts and others [3]. Measured spectral distribution of emitted light provides some important data.…”

Section: Spectral Distribution Changementioning

confidence: 99%

Parameters of white LEDs respecting operational conditions

Doležal¹,

Sláma²,

Pavelka³

2015

Proceedings of the 21st International Conference LIGHT SVĚTLO 2015

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IntroductionUsing of white LEDs (Light Emitting Diodes) for general lighting is on rise. It is caused by several factorscontinuously decreasing prices of LEDs, variable construction designs of luminaires, LED luminaires are suitable for implementation to advanced lighting systems due to their good controllability and others. But this rise brings new challenges for both researchers and manufacturers in the area of understanding the behaviour of LED parameters under real operating conditions. Current state of light parameters stability research is mostly focused on decrease of luminous flux during lifetime and influence of junction temperature on luminous flux. However using white LEDs especially for general lighting is conditioned by fulfilling of other parameter limits -operating voltage, luminous efficacy, colour rendering index, chromaticity temperature. Therefore the data based on spectral distribution changes of white LEDs respecting possible operational conditions are much more convenient for evaluation of possible influences on LED light sources.

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