NL1038825C2 - Electric supply assembly for at least one led. - Google Patents

Electric supply assembly for at least one led. Download PDF

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Publication number
NL1038825C2
NL1038825C2 NL1038825A NL1038825A NL1038825C2 NL 1038825 C2 NL1038825 C2 NL 1038825C2 NL 1038825 A NL1038825 A NL 1038825A NL 1038825 A NL1038825 A NL 1038825A NL 1038825 C2 NL1038825 C2 NL 1038825C2
Authority
NL
Netherlands
Prior art keywords
led
power supply
supply unit
converter
unit according
Prior art date
Application number
NL1038825A
Other languages
Dutch (nl)
Inventor
Hermannus Gerhardus Maria Silderhuis
Original Assignee
Hermannus Gerhardus Maria Silderhuis
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hermannus Gerhardus Maria Silderhuis filed Critical Hermannus Gerhardus Maria Silderhuis
Priority to NL1038825A priority Critical patent/NL1038825C2/en
Priority to EP12724772.4A priority patent/EP2740323A1/en
Priority to PCT/NL2012/050345 priority patent/WO2012158035A1/en
Application granted granted Critical
Publication of NL1038825C2 publication Critical patent/NL1038825C2/en

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/10—Controlling the intensity of the light
    • H05B45/14—Controlling the intensity of the light using electrical feedback from LEDs or from LED modules
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/10—Controlling the intensity of the light
    • H05B45/18—Controlling the intensity of the light using temperature feedback
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
    • H05B45/56—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits involving measures to prevent abnormal temperature of the LEDs

Landscapes

  • Circuit Arrangement For Electric Light Sources In General (AREA)
  • Dc-Dc Converters (AREA)
  • Led Devices (AREA)

Description

Electric supply assembly for at least one LED
The present invention relates to an electric supply assembly for supplying at least one LED with electric energy. When driving a LED with an electric supply usually the LED is driven to about its nominal maximum allowable 5 power. By doing so the junction temperature of the (power) LED reaches a high temperature, viz. 50°C or more. Due to this high temperature the life expectancy of the LED expressed in terms of a decrease of its light output in comparison with the electric input to e.g. 70% of its 10 initial value leaves to be desired.
It is a purpose of the invention to provide an electric supply assembly for driving at least one LED in a way such that the junction temperature is kept on a relatively low value, e.g. 35°C or less.
15 By using such a supply assembly the life expectancy of the LED can substantially be extended, e.g. without any technical problems to a life duration of far over than 100,000 hours.
With a view of the above, the invention provides 20 an electric supply assembly for supplying at least one LED with electrical energy, said supply assembly comprising: - terminals for receiving primary electric energy from a source, e.g. the power mains or a battery; - a controllable converter, the power input of 25 which is connected with said terminals, which converter converts the primary electric energy from the source into secondary electric energy which is specifically suitable for driving the at least one LED, which at least one LED is connectable through a power output with said converter; 30 - measuring means forming part of the converter for measuring at least two of: 1038825 2 (a) the output voltage U of the converter; (b) the output current I of the converter; (c) the differential resistance rd = dU/dl; and - a calculating assembly for determining, on basis 5 of at least two of U, I, dU/dl the junction temperature of the at least one LED, which calculating assembly is connected with a control input of the converter, - the control taking place in a way such that the junction temperature is limited to a chosen maximum value.
10 In a preferred embodiment the supply assembly is engineered in a way such that the secondary electric energy corresponds with an intermitting DC voltage and the measuring means measure at least two of U, I, dU/dl in the active periods.
15 This can be explained as follows: I = Is [ exp (qU/kT) - 1] (1) dU/dl = rd = kT/ql (2) 20 T = (ql • (dU/dl)) / k (3)
Relation (1) shows the relation between the current I through the pn-junction of a LED, and the voltage 25 U over this junction.
Ia is the saturation current of the junction, which is highly temperature dependent. In the range of room temperature, about 300K, Is increases with a factor 2 for every 10°C temperature increase in germanium, and 6°C
30 temperature in silicium. The temperature coefficient of the forward voltage for a diode, e.g. a LED, with constant current amounts to about -2 mV.K-1.
» 3
The derivative of the voltage to the current in relation (1) gives the differential resistance rd of the diode according to expression (2).
Since at room temperature k.Tl * 26 mV, as an 5 example with a current of 1 mA the differential resistance amounts to about 26 Q. Relation (2) is valid for all diodes and is independent on material Constances. From relation (2) the junction temperature can be derived, see relation (3).
The calculating assembly can, on basis of this 10 relation (3), e.g. using suitable and adapted software, determine the junction temperature from the current as measured and the differential resistance.
A common LED, e.g. of the manufactures Cree, Philips, Nichea or Lumiled can be driven up to e.g. 350 mW. 15 At such a power the junction temperature rises to substantially over 50°C. In order to limit the junction temperature to a substantially lower value the LED is driven with a maximum power of about 250 mW. Due to this end, if possible by using specific cooling provisions, the junction 20 temperature is limited. In combination with the control strategy described herein above a life expectancy of well over 100,000 hours can be realized.
According to an aspect of the invention the supply assembly is characterized in that the converter has a 25 control input for receiving a dim signal, in a way such that by adjusting the dim signal the secondary electric energy supplied by the converter to at least one connected LED is correspondingly adjusted, and thus the light yield of said at least one LED is correspondingly adjusted.
30 In a specific embodiment the light yield of the at least one LED can be adjusted on discrete values, e.g. about 25%, 50%, 75% and 100% of a chosen maximum value.
4
In another embodiment the supply assembly comprises manual operating means for manually adjusting the dim signal by a user.
In yet a further embodiment the supply assembly 5 comprises adjusting means responding automatically to an event for adjusting the dim signal to an other value at the beginning and/or the end of the event.
E.g. such supply assembly may be designed such that the adjusting means comprise a light sensor sensing the 10 environment light intensity, in a way such that the light yield of the at least one LED is adjusted in a desired manner to the environment light intensity sensed by said light sensor.
According to another aspect of the invention the 15 adjusting means comprise detection means for detecting the presence of an arriving person or vehicle, in a way such that the light yield of the at least one LED is adapted in a desired manner to such person or vehicle detected by the detection means.
20 Such a supply assembly may be designed in a way such that the light yield of the at least one LED has two levels, viz. (1) an active level equalling a chosen maximum level, and (2) a passive level amounting to less than about 50%, preferably 40%, more preferably 30% or less, of said 25 maximum level, which active level is adjusted when the detection means detect an arriving person or vehicle, and which passive level is adjusted either when detecting the leaving of a person or vehicle, or after passing of a chosen time period after detecting an arriving person or vehicle.
30 In the case that e.g. there are no visitors in a parking garage, the light intensity of the LEDs may be kept on a stationary value of about 30% of the maximum value.
5
Presence sensors added to the supply assemblies present in the garage can detect the entering of at least one vehicle and/or at least one visitor, in which case the intensity is increased to 100%, which is defined by 5 preference as 250 mW for one LED having a maximum power of 350 mW. After some time of after detection the absence of moving vehicles or visitors the intensity is switched down to 30%.
The converter may be of the switching type.
10 The calculating unit may be of the digital type.
According to a further aspect of the invention the maximum junction temperature amounts to about 50°C, preferably 40°C, more preferably 30°C or less.
The at least one LED may be electrically charged 15 with an electric power of a maximum of about 90%, preferably 80%, more preferably 70% of its nominal maximum power.
Furthermore, the invention relates to a combination of (a) a support plate, e.g. a printed circuit board, 20 (b) a supply assembly according to any one of the preceding claims, and (c) at least one LED, which support plate is thermally conductive and is thermally coupled with the at least one LED, in a way such 25 that the support plate is effective for discharging heat from the at least one LED.
In such combination the support plate may comprise a layer of heat conductive ceramic material, at least at the or each outer surface directed to the at least one LED, e.g. 30 is composed entirely from a heat conducting ceramic material.
1038825

Claims (15)

1. Elektrische voedingseenheid voor het aan ten minste één LED toevoeren van elektrische energie, welke voedingseenheid omvat: - aansluitingen voor het ontvangen van primaire 5 elektrische energie van een bron, bijvoorbeeld het lichtnet of een batterij; - een bestuurbare omzetter, waarvan de vermogensingang met die aansluitingen verbonden is, welke omzetter de van de bron afkomstige primaire elektrische 10 energie omzet in voor het drijven van de ten minste ene LED specifiek geschikte secundaire elektrische energie, welke ten minste ene LED via een vermogensuitgang met de omzetter verbindbaar is; - van de omzetter deel uitmakende meetmiddelen 15 voor het meten van ten minste twee van: (a) de uitgangsspanning U van de omzetter; (b) de uitgangsstroom I van de omzetter; (c) de differentiaalweerstand rd = dU/dl; en - een berekeningseenheid voor het op basis van ten 20 minste twee van U, I, dU/dl bepalen van de junctietemperatuur van de ten minste ene LED, welke berekeningseenheid met een besturingsingang van de omzetter verbonden is, - waarbij de besturing zodanig plaatsvindt, dat de 25 junctietemperatuur tot een gekozen maximale waarde begrensd wordt.An electrical power supply unit for supplying electrical energy to at least one LED, which power supply unit comprises: - terminals for receiving primary electrical energy from a source, for example the mains or a battery; - a controllable converter, the power input of which is connected to those connections, which converter converts the primary electrical energy from the source into secondary electrical energy specifically suitable for driving the at least one LED, which at least one LED via a power output can be connected to the inverter; - measuring means 15 forming part of the converter for measuring at least two of: (a) the output voltage U of the converter; (b) the output current I of the converter; (c) the differential resistance r d = dU / d1; and - a calculation unit for determining the junction temperature of the at least one LED on the basis of at least two of U, I, dU / d1, which calculation unit is connected to a control input of the converter, the control taking place in such a way, that the junction temperature is limited to a selected maximum value. 2. Voedingseenheid volgens conclusie 1, waarin de secundaire elektrische energie correspondeert met een 30 intermitterende gelijkspanning en de meetmiddelen ten minste twee van U, I, dU/dl in de actieve perioden meten.2. Power supply unit as claimed in claim 1, wherein the secondary electrical energy corresponds to an intermittent direct voltage and the measuring means measure at least two of U, I, dU / dl in the active periods. 3. Voedingseenheid volgens een der voorgaande conclusies, waarin de omzetter een besturingsingang voor het ontvangen van een dimsignaal bezit, zodanig, dat door het 5 instellen van het dimsignaal de door de omzetter aan ten minste één aangesloten LED toegevoerde secundaire elektrische energie corresponderend wordt ingesteld, en aldus de lichtopbrengst van die ten minste ene LED corresponderend wordt ingesteld. 103. A power supply unit according to any one of the preceding claims, wherein the converter has a control input for receiving a dimming signal, such that by adjusting the dimming signal the secondary electrical energy supplied by the converter to at least one connected LED is adjusted correspondingly, and thus the light output of said at least one LED is adjusted accordingly. 10 4. Voedingseenheid volgens conclusie 3, waarin de lichtopbrengst van de ten minste ene LED op discrete waarden kan worden ingesteld, bijvoorbeeld circa 25%, 50%, 75% en 100% van een gekozen maximale waarde. 15A power supply unit according to claim 3, wherein the light output of the at least one LED can be set to discrete values, for example approximately 25%, 50%, 75% and 100% of a selected maximum value. 15 5. Voedingseenheid volgens conclusie 3, omvattende handbedieningsmiddelen voor het door een gebruiker met de hand instellen van het dimsignaal.5. Power supply unit as claimed in claim 3, comprising manual operating means for manually setting the dimming signal by a user. 6. Voedingseenheid volgens conclusie 3, omvattende automatisch op een gebeurtenis reagerende instelmiddelen voor het bij het begin en/of het einde van de gebeurtenis op een andere waarde instellen van het dimsignaal.A power supply unit according to claim 3, comprising automatic event responsive adjustment means for adjusting the dimming signal to a different value at the start and / or end of the event. 7. Voedingseenheid volgens conclusie 6, waarin de instelmiddelen een lichtsensor omvatten, die de omgevingslichtsterkte waarneemt, zodanig dat de lichtopbrengst van de ten minste ene LED op een gewenste wijze wordt aangepast aan de door de lichtsensor waargenomen 30 omgevingslichtsterkte.7. Power supply unit according to claim 6, wherein the adjusting means comprise a light sensor, which detects the ambient light intensity, such that the light output of the at least one LED is adjusted in a desired manner to the ambient light intensity perceived by the light sensor. 8. Voedingseenheid volgens conclusie 6, waarin de instelmiddelen detectiemiddelen omvatten die de aanwezigheid van de aankomst van een persoon of voertuig kunnen detecteren, zodanig dat de lichtopbrengst van de ten minste ene LED op een gewenste wijze wordt aangepast aan de door de detectiemiddelen gedetecteerde aankomst van een persoon of 5 een voertuig.8. Power supply unit according to claim 6, wherein the setting means comprise detection means capable of detecting the presence of the arrival of a person or vehicle, such that the light output of the at least one LED is adapted in a desired manner to the arrival of the detection means detected by the detection means a person or 5 a vehicle. 9. Voedingseenheid volgens conclusie 8, waarin de lichtopbrengst van de ten minste ene LED twee niveaus bezit, namelijk (1) een actief niveau dat gelijk is aan een gekozen 10 maximaal niveau, en (2) een passief niveau, dat minder dan circa 50%, bij voorkeur 40%, nog meer bij voorkeur 30% of lager, van dat maximale niveau bedraagt, welk actieve niveau wordt ingesteld bij het door de detectiemiddelen detecteren van de aankomst van een persoon of een voertuig, en welk 15 passieve niveau wordt ingesteld, ofwel bij het detecteren van het vertrek van een persoon of een voertuig, ofwel na het verstrijken van een gekozen tijdsperiode na het detecteren van de aankomst van een persoon of een voertuig.9. Power supply unit according to claim 8, wherein the light output of the at least one LED has two levels, namely (1) an active level that is equal to a chosen maximum level, and (2) a passive level that is less than approximately 50 %, preferably 40%, even more preferably 30% or lower, of that maximum level, which active level is set when the detection means detect the arrival of a person or a vehicle, and which passive level is set , either upon detecting the departure of a person or a vehicle, or after a selected period of time has elapsed after detecting the arrival of a person or a vehicle. 10. Voedingseenheid volgens een der voorgaande conclusies, waarin de omzetter van het schakelende type is.10. A power supply unit according to any one of the preceding claims, wherein the converter is of the switching type. 11. Voedingseenheid volgens een der voorgaande conclusies, waarin de berekeningseenheid van het digitale 25 type is.11. Power supply unit according to any one of the preceding claims, wherein the calculation unit is of the digital type. 12. Voedingseenheid volgens een der voorgaande conclusies, waarin de maximale junctietemperatuur ongeveer 50°C, bij voorkeur 40°C, nog meer bij voorkeur 30°C of 30 lager, bedraagt.A power supply unit according to any one of the preceding claims, wherein the maximum junction temperature is approximately 50 ° C, preferably 40 ° C, even more preferably 30 ° C or 30 lower. 13. Voedingseenheid volgens een der voorgaande conclusies, waarin de ten minste ene LED elektrisch wordt belast met een elektrisch vermogen van maximaal ongeveer 90%, bij voorkeur 80%, nog meer bij voorkeur 70%, van zijn nominale maximale vermogen.A power supply unit according to any one of the preceding claims, wherein the at least one LED is electrically charged with an electrical power of at most about 90%, preferably 80%, even more preferably 70%, of its nominal maximum power. 14. Combinatie van (a) een dragerplaat, bijvoorbeeld een gedrukteschakeling-plaat, (b) een voedingseenheid volgens een der voorgaande conclusies, en 10 (c) ten minste één LED, welke dragerplaat warmtegeleidend is en thermisch met de ten minste ene LED gekoppeld is, zodanig, dat de dragerplaat effectief is voor het afvoeren van van de ten minste ene LED afkomstige warmte. 1514. Combination of (a) a carrier plate, for example a printed circuit board, (b) a power supply unit according to any one of the preceding claims, and (c) at least one LED, which carrier plate is thermally conductive and thermally coupled to the at least one LED is such that the carrier plate is effective for dissipating heat from the at least one LED. 15 15. De combinatie volgens conclusie 14, waarin de dragerplaat althans aan het of elk naar de ten minste ene LED gerichte buitenvlak een laag warmtegeleidend keramisch materiaal omvat, bijvoorbeeld geheel uit warmtegeleidend 20 keramisch materiaal bestaat.15. The combination as claimed in claim 14, wherein the carrier plate comprises a layer of heat-conducting ceramic material at least on the or each outer surface facing the at least one LED, for example entirely consisting of heat-conducting ceramic material.
NL1038825A 2011-05-19 2011-05-19 Electric supply assembly for at least one led. NL1038825C2 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
NL1038825A NL1038825C2 (en) 2011-05-19 2011-05-19 Electric supply assembly for at least one led.
EP12724772.4A EP2740323A1 (en) 2011-05-19 2012-05-16 Electric supply assembly for at least one led
PCT/NL2012/050345 WO2012158035A1 (en) 2011-05-19 2012-05-16 Electric supply assembly for at least one led

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL1038825 2011-05-19
NL1038825A NL1038825C2 (en) 2011-05-19 2011-05-19 Electric supply assembly for at least one led.

Publications (1)

Publication Number Publication Date
NL1038825C2 true NL1038825C2 (en) 2012-11-20

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NL1038825A NL1038825C2 (en) 2011-05-19 2011-05-19 Electric supply assembly for at least one led.

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EP (1) EP2740323A1 (en)
NL (1) NL1038825C2 (en)
WO (1) WO2012158035A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT17240U1 (en) 2016-08-22 2021-09-15 Tridonic Gmbh & Co Kg Method and arrangement for operating a load which contains at least one LED module

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2224374A (en) * 1988-08-24 1990-05-02 Plessey Co Plc Temperature control of light-emitting devices
US20060202914A1 (en) * 2005-03-03 2006-09-14 Ian Ashdown Method and apparatus for controlling thermal stress in lighting devices
US7598685B1 (en) * 2004-09-20 2009-10-06 Exclara, Inc. Off line LED driver with integrated synthesized digital optical feedback
WO2010049882A2 (en) * 2008-10-30 2010-05-06 Nxp B.V. Lighting unit with temperature protection

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2224374A (en) * 1988-08-24 1990-05-02 Plessey Co Plc Temperature control of light-emitting devices
US7598685B1 (en) * 2004-09-20 2009-10-06 Exclara, Inc. Off line LED driver with integrated synthesized digital optical feedback
US20060202914A1 (en) * 2005-03-03 2006-09-14 Ian Ashdown Method and apparatus for controlling thermal stress in lighting devices
WO2010049882A2 (en) * 2008-10-30 2010-05-06 Nxp B.V. Lighting unit with temperature protection

Also Published As

Publication number Publication date
EP2740323A1 (en) 2014-06-11
WO2012158035A1 (en) 2012-11-22

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