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1
Content available Comparative study of cooling of automobile LED headlights without and with fins and finding comfortable operating conditions
Mishra Manbodh Kumar, Chandramohan V. P., Balasubramanian Karthik
Archive of Mechanical Engineering
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2019
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Vol. LXVI, nr 3
295--314
EN
LED light must be cooled to avoid reaching a certain temperature. Two different 3D practical domains of LED light are modelled, (i) square aluminium plate with a cylindrical plate and an LED module (model I), (ii) the same provision of model I with 25 fins (model II). ANSYS 16.0 is used for solving the problem. Temperature distribution, junction temperature (Tj ) and heat flux are estimated. Analyses are carried out for various ambient temperatures (Ta) and for different LED power dissipations (Q) to identify the safe operating conditions. In model I, it is found that 38% of working conditions go beyond the critical limit of Tj and it is reduced to 21.4% in model II. In model II, for low Ta of 30 and 40 C with all Q considered in this analysis are safer. If Ta is between 30 and 80 C, then Q must be maintained at 0.5 to 1.25 W. Beyond this, conditions are not safe.
2
Content available Influence of junction temperature on the spectral power distribution of Light Emitting Diodes
Budzyński Ł
Challenges of Modern Technology
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2015
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Vol. 6, no. 4
3--7
EN
This article describes electrical method for measuring junction temperature of high power LEDs. Measurement system consisting of a temperature controller and a thermostatic chamber was designed and constructed. A number of studies of LEDs in a typical thermal conditions that exist in luminaries were performed. Basing on these results, influence of junction temperature on luminous flux and spectral power distribution of LED was determined. Obtained results allow to optimize the construction of LED lighting fixtures, in the ambient temperature range from 0°C to 100°C, especially in the aspect of improving the photometric properties of the luminaire.
3
Content available Oddziaływanie termiczne pomiędzy źródłami hp LED zainstalowanymi na wspólnym radiatorze
Różowicz A., Baran K.
Prace Instytutu Elektrotechniki
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2014
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Z. 266
87--97
PL
W artykule zaprezentowano model matematyczny pozwalający wyznaczyć temperaturę radiatora, na którym może być zainstalowana dowolna ilość sprzężonych ze sobą termicznie źródeł ciepła. Na podstawie modelu symulacyjnie wyznaczono temperaturę płyty aluminiowej, na której zainstalowano źródła światła LED, będące źródłami ciepła. Symulację przeprowadzono dla kilku przypadków, w których zmieniana była ilość, moc oraz odległość pomiędzy źródłami LED. Oszacowany w ten sposób rozkład temperatury radiatora może być wykorzystany do obliczenia temperatury złącza, która wpływa na podstawowe parametry źródeł LED.
EN
The article presents the mathematical model allowing to determine the temperature of the radiator, on which there can be installed any number of heat sources coupled with each other. Based on the model, the temperature of the aluminium plate with installed LED light sources (being the sources of heat) was determined by simulation. The simulation was performed for several cases, in which the amount, power and the distance between LED sources was different. Thus estimated distribution of the radiator can be used to calculate the temperature of the junction, chich influences the basic parameters of LED sources.
4
Content available remote Improved Electrical Measurement Method for Junction Temperature of Light Emitting Diodes
Shen H., Han K., Liu M., Fan S.
Przegląd Elektrotechniczny
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2012
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R. 88, nr 3b
180-184
EN
The electrical test method (ETM) is used to measure the junction temperature Tj of high brightness LEDs. NI 5922 digitizer and Keithley S2400 source meter were used to build the measurement system. Various measurement currents were used under 1MHz sampling rate. Results of different measurement currents are found to be the same under the same sampling rate and measurement error can be found under low sampling rates. When sampling rate is down to 0.2kHz, measurement error is up to 13.7%.
PL
Zaproponowano metodę pomiaru temperatury złącza diody LED. Określono błąd metody dla różnych częstotliwości próbkowania.
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