Effects of the junction temperature on the dynamic resistance of white LEDs

Gacio, D.; Alonso, J.M.; Garcia, J.; Perdigão, M. S.; Saraiva, E. S.; Bisogno, F.E.

doi:10.1109/apec.2012.6166052

Cited by 9 publications

(21 citation statements)

References 18 publications

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“…These experimental tests showed the same results as reported in [19], as there were two devices featuring a fairly linear temperature dependence: the Golden Dragon Plus and the Luxeon K2 with TFFC, whereas the other two devices showed a more pronounced quadratic relation.…”

Section: Thermal Characterization Of Ledssupporting

confidence: 81%

“…Therefore, two complementary studies were developed in order to determine the LED linear model: firstly, the forward-voltage method will be applied to the test lamps in order to determine the I-V curve as a function of the junction temperature [13]- [18], which in turn will lead to the obtaining of the V D -T j characteristic. This characteristic will eventually be used in order to estimate the junction temperature accurately, as previously applied in [19]. Afterwards, the same small-signal analysis as in [19] will be applied to the entire lamp in order to determine the dynamicresistance temperature dependency.…”

Section: Thermal Characterization Of Ledsmentioning

confidence: 99%

“…This characteristic will eventually be used in order to estimate the junction temperature accurately, as previously applied in [19]. Afterwards, the same small-signal analysis as in [19] will be applied to the entire lamp in order to determine the dynamicresistance temperature dependency. These tests will allow the actual linear model to be obtained for a given operation point.…”

Section: Thermal Characterization Of Ledsmentioning

confidence: 99%

“…The ambient temperature was varied from -10 ºC to 120 ºC. The pulse width was set to 40 μs in order to get rid of electrical noise while achieving negligible LED self-heating [14], [19], [20]- [23]. The experimental arrangement is illustrated in Fig.…”

Section: Thermal Characterization Of Ledsmentioning

confidence: 99%

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Study on passive self-equalization of parallel-connected LED strings

Gacio¹,

Alonso

Garcia

et al. 2013

2013 International Conference on New Concepts in Smart Cities: Fostering Public and Private Alliances (SmartMILE)

Self Cite

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Parallel connection of several LED strings is a practical way to reduce the overall lamp voltage when a large number of emitters is needed. However, this connection might lead to high current mismatches between strings due to the dispersion of characteristics that even binned devices feature. Several techniques have been proposed in order to eliminate or, at least, reduce the forward current mismatch between paralleled strings. Provided that a cost-effective design is pursued, passive self-equalization of LED strings will be studied in this paper, where the dynamic resistance will be considered as the equalizing resistor. Thus, a statistical study will firstly be developed on four commercial devices in order to determine the forward voltage deviation in both binned and unbinned LEDs. Then, the dynamic resistance will accurately be determined for the operating current in a wide temperature range by the procedure followed in previous works, since this parasitic effect will be employed as the equalizing resistor. The I-V and R D -T j curves will be thus experimentally obtained for a large sample. Once the thermal and statistical characterizations are done, the study of the LED linear model will be performed in order to determine the impact on forward current mismatches that forward voltage and dynamic resistance variations imply in both binned and unbinned LEDs. Finally, experimental results will show that binned LEDs are suitable for self-equalization even for a tight current-mismatch tolerance, especially for a significant number of series-connected LEDs in each string.

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Section: Thermal Characterization Of Ledssupporting

confidence: 81%

Section: Thermal Characterization Of Ledsmentioning

confidence: 99%

Section: Thermal Characterization Of Ledsmentioning

confidence: 99%

Section: Thermal Characterization Of Ledsmentioning

confidence: 99%

See 2 more Smart Citations

Study on passive self-equalization of parallel-connected LED strings

Gacio¹,

Alonso

Garcia

et al. 2013

2013 International Conference on New Concepts in Smart Cities: Fostering Public and Private Alliances (SmartMILE)

Self Cite

View full text Add to dashboard Cite

show abstract

“…For a given current, the voltage drop is of order of mV/ºC. This dynamic behavior affects the LED driver design, as the continuous drop in LED voltage (due to temperature increase) causes an increase in the LED current, yielding a positive feedback behavior that should be considered in driver design [19]. The junction temperature increase may lead to light output decay and lifetime reduction or, in worst cases, catastrophic failure of the LED device…”

Section: Drivers For Led Luminairesmentioning

confidence: 99%

Thermal Management of Led Luminaires Based on Computational Fluid Dynamic

Iaronka¹,

Bender²,

Marchesan³

2015

Eletrônica de Potência

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-Large LED (light-emitting diodes) clusters are currently designed to replace the lamps commonly used in parks, roadways, tunnels and street lighting. However, the success of these designs is heavily dependent on the performance of the thermal management. Thermal performance affects light extraction, reliability and lifetime of LED lamp. This paper proposes thermal management solutions to improve the design of LED luminaires. These solutions include natural convection and forced air convection into a closed cooling loop. The LED driver influence on luminaire heating is also evaluated in this paper.

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Simplified electrical modelling of power LEDs for DC–DC converter analysis and simulation

Osorio

Alonso

Pinto

et al. 2017

Circuit Theory & Apps

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SUMMARYThis paper presents a model of power light emitting diodes (LEDs) based on electrical variables and considering the concept of LED 'equivalent resistance', which has previously been used in discharge lamp modelling and is suitable to achieve fast simulations of LED converter systems. The model can be obtained with only some simple electrical measurements, thus making its implementation quite straightforward. The proposed model is oriented to the electronic engineering area, and it has special application for the simulation of the electrical behaviour of LEDs and dc-dc converter systems by using software like Simulink. In addition, the proposed model can also be employed for the theoretical analysis and design of LED drivers. Experimental and simulation results are obtained proving the feasibility of the proposed model.

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Effects of the junction temperature on the dynamic resistance of white LEDs

Cited by 9 publications

References 18 publications

Study on passive self-equalization of parallel-connected LED strings

Study on passive self-equalization of parallel-connected LED strings

Thermal Management of Led Luminaires Based on Computational Fluid Dynamic

Simplified electrical modelling of power LEDs for DC–DC converter analysis and simulation

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