EP4099803A1 - Abstimmbares weisses led-modul - Google Patents

Abstimmbares weisses led-modul Download PDF

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Publication number
EP4099803A1
EP4099803A1 EP21177665.3A EP21177665A EP4099803A1 EP 4099803 A1 EP4099803 A1 EP 4099803A1 EP 21177665 A EP21177665 A EP 21177665A EP 4099803 A1 EP4099803 A1 EP 4099803A1
Authority
EP
European Patent Office
Prior art keywords
led
lighting means
led lighting
led module
module
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP21177665.3A
Other languages
English (en)
French (fr)
Inventor
Istvan Bakk
András Mozsáry
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tridonic GmbH and Co KG
Original Assignee
Tridonic GmbH and Co KG
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 Tridonic GmbH and Co KG filed Critical Tridonic GmbH and Co KG
Priority to EP21177665.3A priority Critical patent/EP4099803A1/de
Priority to PCT/EP2022/064673 priority patent/WO2022253789A1/en
Priority to EP22734156.7A priority patent/EP4327630A1/de
Publication of EP4099803A1 publication Critical patent/EP4099803A1/de
Withdrawn legal-status Critical Current

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    • 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]
    • H05B45/20—Controlling the colour of the light
    • 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]
    • H05B45/30—Driver circuits
    • H05B45/32—Pulse-control circuits
    • H05B45/325—Pulse-width modulation [PWM]
    • 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]
    • H05B45/30—Driver circuits
    • H05B45/34—Voltage stabilisation; Maintaining constant voltage

Definitions

  • the present disclosure relates to lighting technology, and in particular to a tunable white LED module and a luminaire comprising the same.
  • Tunable white describes a variable color temperature from warm white to cool white light, by mixing light from warm white and cool white LEDs.
  • the object of the present disclosure is to provide a smaller and less expensive tunable white LED module and a corresponding luminaire comprising the same.
  • a first aspect of the present disclosure relates to an LED module.
  • the LED module comprises input terminals connectable to an LED driver; a plurality of LED lighting means having different color temperatures; an auxiliary load connected between the input terminals and the plurality of LED lighting means; and one or more first switches configured to select, in dependence of one or more first PWM control signals, one of the plurality of LED lighting means for feeding by the LED driver.
  • the auxiliary load may comprise a Zener diode connected in parallel to the plurality of LED lighting means.
  • the auxiliary load may comprise a second switch connected in parallel to the plurality of LED lighting means and configured to shunt, in dependence of a second control signal, the plurality of LED lighting means.
  • the auxiliary load may comprise an inductor connected in series between the input terminals and the plurality of LED lighting means.
  • a respective switching frequency of the one or more first PWM control signals may comprise an integer multiple of a minimum switching frequency.
  • the LED module may further comprise a respective capacitor connected in parallel to each of the plurality of LED lighting means and having a same capacitance that depends on the minimum switching frequency.
  • the LED module may further comprise a respective diode connected in series with each of the plurality of LED lighting means.
  • a respective duty cycle of the one or more first PWM control signals may depend on the respective switching frequency of the one or more first PWM control signals and on a proportion of the feeding of the plurality of LED lighting means relative to one another.
  • the plurality of LED lighting means may respectively comprise an LED string.
  • the plurality of LED lighting means may comprise first LED lighting means having a color temperature greater than or equal to 5.000 K; and second LED lighting means having a color temperature greater than or equal to 2.700 K and less than or equal to 3.000 K.
  • a second aspect of the present disclosure relates to a luminaire.
  • the luminaire comprises an LED module according the first aspect or any of its implementations; and an LED driver connected to input terminals of the LED module and configured to feed the LED module off a mains grid.
  • the LED driver may be configured to feed a constant current.
  • the present disclosure provides tunable white illumination having high color consistency, i.e., a broad dimming range without a change of color temperature.
  • a ratio of cold white to warm white illumination is maintained with high accuracy without any A/D converters or feedback regulation loops.
  • a structural setup of the tunable white illumination is simplified and miniaturized, a number of components is small, and cost is reduced.
  • FIG. 1 illustrates a luminaire 1 comprising an LED module 4 in accordance with the present disclosure.
  • the LED module 4 comprises input terminals 41 which are generally connectable to an LED driver 3.
  • the LED driver 3 is connected to the input terminals 41 of the LED module 4 and configured to feed the LED module 4 off a mains grid 2.
  • the LED driver 3 may be configured to feed a constant current (CC).
  • the LED module 4 further comprises a plurality of LED lighting means 42, 43 having different color temperatures.
  • the plurality of LED lighting means 42, 43 may respectively comprise an LED string.
  • the plurality of LED lighting means 42, 43 may comprise first LED lighting means 42 having a color temperature greater than or equal to 5.000 K ("cool white") and second LED lighting means 43 having a color temperature greater than or equal to 2.700 K and less than or equal to 3.000 K ("warm white”).
  • the LED module 4 generally comprises one or more first switches 45A; 45B, 45C configured to select, in dependence of one or more first PWM control signals 46A; 46B, 46C, one of the plurality of LED lighting means 42, 43 for feeding by the LED driver 3.
  • the one or more first PWM control signals 46A; 46B, 46C may be provided by a control unit 50 such as a microcontroller.
  • a 16-bit resolution of the one or more first PWM control signals 46A; 46B, 46C may attain an accuracy sufficient for state-of-art color consistency.
  • the LED module 4 comprises a single first switch 45A configured to select, in dependence of a single first PWM control signal 46A, one of the plurality of LED lighting means 42, 43 for feeding by the LED driver 3.
  • the first switch 45A is configured to toggle between the two branches of the first LED lighting means 42 and the second LED lighting means 43.
  • a PWM duty cycle of the first PWM control signal 46A determines a ratio of cool white and warm white illumination by the plurality of LED lighting means 42, 43.
  • the switching frequency ⁇ is the same for all branches, and the PWM duty cycles of the branches add up to 1.
  • a single-channel CC LED driver 3 may suffice to drive the plurality of LED lighting means 42, 43 of the LED module 4, which may in turn reduce a form factor and a cost with respect to a two-channel LED driver.
  • the single-channel CC LED driver 3 may have a feed / output current tolerance relaxed beyond ⁇ 5% up to ⁇ 10%, which may facilitate further cost savings and miniaturization.
  • the LED module 4 further comprises an auxiliary load 44A, 44B, 44C connected between the input terminals 41 and the plurality of LED lighting means 42, 43.
  • the auxiliary load 44A, 44B, 44C may mitigate switching disturbances.
  • the auxiliary load 44A, 44B, 44C may comprise a Zener diode 44A connected in parallel to the plurality of LED lighting means 42, 43.
  • a Zener diode is a special type of diode designed to allow a reversed current to flow when the diode is reverse-biased beyond a certain voltage, known as the Zener voltage, and to allow the reverse current to keep the voltage drop across the Zener diode close to the Zener voltage across a wide range of reverse currents.
  • the Zener diode 44A acts as a shunt regulator by maintaining a nearly constant voltage across itself and across the plurality of LED lighting means 42, 43 when the reverse current through it is sufficient to take it into the Zener breakdown region.
  • FIG. 2 illustrates a luminaire 1 comprising an LED module 4 in accordance with the present disclosure.
  • the auxiliary load 44A, 44B, 44C may comprise a second switch 44B ("dump switch") connected in parallel to the plurality of LED lighting means 42, 43 and configured to shunt, in dependence of a second control signal 47, the plurality of LED lighting means 42, 43.
  • the second control signal 47 may be provided by the control unit 50, too.
  • the second switch 44B thus actively allows current to bypass the plurality of LED lighting means 42, 43 when none of the plurality of LED lighting means 42, 43 is selected for feeding by the LED driver 3.
  • FIG. 3 illustrates a luminaire 1 comprising an LED module 4 in accordance with the present disclosure
  • FIG. 4 illustrates time-dependent feed currents of the LED module 4 of FIG. 3 .
  • CC LED drivers include capacitors at their output for construction reasons (for power factor correction, PFC, for example). In such circumstances, current amplitudes of different branches may differ from each other, so that a non-constant feed current may be observed.
  • a top of FIG. 4 indicates an exemplary first PWM control signal 46A.
  • a "high" level of the first PWM control signal 46A selects the "cool white” first LED lighting means 42 (CW channel) for feeding by the LED driver 3, and a “high” level of the first PWM control signal 46A selects the "warm white” second LED lighting means 43 (WW channel).
  • the first PWM control signal 46A has an 80% duty cycle for the CW channel and a 20% duty cycle for the WW channel.
  • a center of FIG. 4 shows an exemplary feed current provided by a CC LED driver 3 including output capacitors.
  • average currents of 159mA and 414mA are fed into the CW channel and the WW channel, respectively.
  • the CC LED driver 3 fails to provide a constant current and thus over-emphasizes the WW channel.
  • the auxiliary load 44A, 44B, 44C may comprise an inductor 44C ("choke") connected in series between the input terminals 41 and the plurality of LED lighting means 42, 43.
  • the inductor 44C mitigates the effect of the output capacitor inside the CC LED driver 3 by a change in a strength of a magnetic field in response to a change in current amplitude through the inductor.
  • FIG. 4 depicts an exemplary feed current provided by the same CC LED driver 3 including output capacitors to the LED module 4 including the inductor 44C.
  • a same average current for the CW channel and the WW channel results in a color temperature in accordance with the PWM duty cycles.
  • FIG. 5 illustrates a luminaire 1 comprising an LED module 4 in accordance with the present disclosure.
  • the LED module 4 comprises all the circuit elements of FIGS. 1 - 3 to indicate that these implementations may be combined with one other. Beyond the drawn versions, combinations of two circuit elements are also possible, i.e., 44A and 44C, 44B and 44C, as well as 44A and 44B.
  • the LED module 4 may further comprise a respective capacitor 48 ("branch capacitor") connected in parallel to each of the plurality of LED lighting means 42, 43 and having a same capacitance value that depends on a switching frequency of the first PWM control signal 46A. As will be explained in more detail in connection with FIG. 6 , this switching frequency may be termed minimum switching frequency ⁇ 0 .
  • the respective capacitor 48 maintains a current flow and continuous emission of light from LED branch 42 during the off-state of switch 45B.
  • "branch capacitor” 48 maintains a current flow and continuous emission of light from LED branch 43 during the off-state of switch 45C. Continuous emission of light is beneficial against TLA (Temporal Light Artefact) like for example visible flicker of a luminaire.
  • TLA Temporal Light Artefact
  • the LED module 4 may further comprise a respective diode 49 ("branch diode”) connected in series with each of the plurality of LED lighting means 42, 43.
  • branch diode a respective diode 49
  • the respective diode 49 may mitigate reverse bias condition on off-state switches 45A, 45B, 45C.
  • Power MOSFET types of switches may not tolerate reverse bias voltage across Drain-Source during off state.
  • FIG. 6 illustrates a luminaire 1 comprising an LED module 4 in accordance with the present disclosure.
  • the LED module of FIG. 6 differs from the implementation of FIG. 5 in that the single first PWM switch 45A is replaced by a plural of first switches 45B, 45C configured to select, in dependence of a corresponding plural of first PWM control signals 46B, 46C, one of the plurality of LED lighting means 42, 43 for feeding by the LED driver 3.
  • the switching frequency ⁇ is not necessarily the same for the CW channel and the WW channel, and the PWM duty cycles of these branches do not necessarily add up to 1 . In other words, this implementation enables a dimming operation.
  • decoupling the CW channel and the WW channel from one another serves the following purpose: Even in the presence of the ripple filters 48, 49, still some small non-zero flicker remains. Its magnitude depends on the capacitance value of the capacitors 48, which in turn relates to the switching frequency of the CW channel and the WW channel.
  • Ripple as used herein may refer to rapid fluctuations of an electrical quantity, such as a current, and may be measured as a ratio of deviations from an average value to this average value.
  • Flicker as used herein may refer to a visible change in brightness of a lighting means due to ripple in its power feed.
  • the use of one PWM pulse per base cycle period 1 / ⁇ 0 increases ripple significantly.
  • a use of multiple PWM pulses per base cycle period may reduce ripple/flicker as this effectively increases switching frequencies.
  • a respective switching frequency of the two first PWM control signals 46B, 46C may comprise an integer multiple of a minimum switching frequency ⁇ 0 (see above) which is common for all first switches 45B, 45C, and which provides an accurate ratio of cool white and warm white illumination.
  • FIG. 7 illustrates a multi-pulse feed of the LED module 4 of FIG. 6 .
  • a respective duty cycle of the two first PWM control signals 46B, 46C may depend on the respective switching frequency of the two first PWM control signals 46B, 46C and on a proportion of the feeding of the plurality of LED lighting means 42, 43 relative to one another.
  • FIG. 8 illustrates a ripple of the branch current of the first LED 42 of FIG. 6 for capacitors 48 of different capacitance.

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  • Circuit Arrangement For Electric Light Sources In General (AREA)
EP21177665.3A 2021-06-04 2021-06-04 Abstimmbares weisses led-modul Withdrawn EP4099803A1 (de)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP21177665.3A EP4099803A1 (de) 2021-06-04 2021-06-04 Abstimmbares weisses led-modul
PCT/EP2022/064673 WO2022253789A1 (en) 2021-06-04 2022-05-31 Tunable white led module
EP22734156.7A EP4327630A1 (de) 2021-06-04 2022-05-31 Abstimmbares weisses led-modul

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP21177665.3A EP4099803A1 (de) 2021-06-04 2021-06-04 Abstimmbares weisses led-modul

Publications (1)

Publication Number Publication Date
EP4099803A1 true EP4099803A1 (de) 2022-12-07

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EP21177665.3A Withdrawn EP4099803A1 (de) 2021-06-04 2021-06-04 Abstimmbares weisses led-modul
EP22734156.7A Pending EP4327630A1 (de) 2021-06-04 2022-05-31 Abstimmbares weisses led-modul

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EP22734156.7A Pending EP4327630A1 (de) 2021-06-04 2022-05-31 Abstimmbares weisses led-modul

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EP (2) EP4099803A1 (de)
WO (1) WO2022253789A1 (de)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2170013A2 (de) * 2008-09-28 2010-03-31 Wanstar Technology Co., Ltd. Hochleistungs-LED-Antriebsschaltung
WO2011135505A1 (en) * 2010-04-30 2011-11-03 Koninklijke Philips Electronics N.V. Dimming regulator including programmable hysteretic down-converter for increasing dimming resolution of solid state lighting loads
US20120200229A1 (en) * 2011-02-07 2012-08-09 Cypress Semiconductor Corporation Mutli-string led current control system and method
EP2958402A1 (de) * 2014-06-19 2015-12-23 Nxp B.V. Dimmbare LED-Beleuchtungsschaltungen
WO2017183979A2 (en) * 2016-04-22 2017-10-26 Eldolab Holding B.V. The invention relates to the field of lighting applications, in particular led based lighting applications
WO2017182266A1 (en) * 2016-04-22 2017-10-26 Philips Lighting Holding B.V. A method of controlling a lighting arrangement, a lighting control circuit and a lighting system.

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2170013A2 (de) * 2008-09-28 2010-03-31 Wanstar Technology Co., Ltd. Hochleistungs-LED-Antriebsschaltung
WO2011135505A1 (en) * 2010-04-30 2011-11-03 Koninklijke Philips Electronics N.V. Dimming regulator including programmable hysteretic down-converter for increasing dimming resolution of solid state lighting loads
US20120200229A1 (en) * 2011-02-07 2012-08-09 Cypress Semiconductor Corporation Mutli-string led current control system and method
EP2958402A1 (de) * 2014-06-19 2015-12-23 Nxp B.V. Dimmbare LED-Beleuchtungsschaltungen
WO2017183979A2 (en) * 2016-04-22 2017-10-26 Eldolab Holding B.V. The invention relates to the field of lighting applications, in particular led based lighting applications
WO2017182266A1 (en) * 2016-04-22 2017-10-26 Philips Lighting Holding B.V. A method of controlling a lighting arrangement, a lighting control circuit and a lighting system.

Also Published As

Publication number Publication date
EP4327630A1 (de) 2024-02-28
WO2022253789A1 (en) 2022-12-08

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