EP4156864A1 - Alimentation de puissance à del - Google Patents

Alimentation de puissance à del Download PDF

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Publication number
EP4156864A1
EP4156864A1 EP22020456.4A EP22020456A EP4156864A1 EP 4156864 A1 EP4156864 A1 EP 4156864A1 EP 22020456 A EP22020456 A EP 22020456A EP 4156864 A1 EP4156864 A1 EP 4156864A1
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EP
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Prior art keywords
power
leds
led
color
channels
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.)
Pending
Application number
EP22020456.4A
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German (de)
English (en)
Inventor
Rene HINKEL
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Dr Ralf Hinkel Holding GmbH
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Hiasset GmbH
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Publication date
Priority claimed from DE102021005158.0A external-priority patent/DE102021005158A1/de
Application filed by Hiasset GmbH filed Critical Hiasset GmbH
Publication of EP4156864A1 publication Critical patent/EP4156864A1/fr
Pending 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]
    • H05B45/30—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]
    • H05B45/20—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]
    • H05B45/40—Details of LED load circuits
    • H05B45/44—Details of LED load circuits with an active control inside an LED matrix
    • H05B45/46—Details of LED load circuits with an active control inside an LED matrix having LEDs disposed in parallel lines
    • 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
    • H05B45/52—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits in a parallel array of LEDs

Definitions

  • the present invention relates to what is claimed in the preamble and accordingly relates to the power supply of LEDs.
  • Light-emitting diodes are increasingly being used for lighting purposes.
  • the light-emitting diodes are often supplied with power from a DC voltage power supply unit with a given output power, which not only allows the user energy-saving lighting, but also offers a wide range of setting options.
  • a user will generally want light that is perceived as white or colored light.
  • White light is obtained by closely arranging and energizing light-emitting diodes of different colors, for example, light-emitting diodes emitting red, green and blue light.
  • the light temperature i.e. the "color" of the emitted light, can be adjusted by feeding power to the red, green and blue light-emitting diodes in different ratios depending on the colour.
  • the brightness can be adjusted, i.e. dimmed, by changing the light-emitting diode supply in the same way for all diodes.
  • a so-called white-light LED in which light that is perceived as "white” is emitted with a fixed predetermined color temperature of e.g. 5500° Kelvin, with a change in the excitation power fed to this so-called white-light LED merely resulting in a change in brightness leads.
  • a so-called white-light LED in which light that is perceived as "white” is emitted with a fixed predetermined color temperature of e.g. 5500° Kelvin, with a change in the excitation power fed to this so-called white-light LED merely resulting in a change in brightness leads.
  • the color intensity i.e. to set whether the emitted light has only a very slight deviation from a given color temperature or whether this color deviation leads to a coloration that is perceived as very intense or "pop".
  • this intensity can be changed by exciting the white light LED particularly strongly for only a low color intensity, while the RGB color diodes are excited overall more weakly in the ratio required for the desired color temperature; conversely, high color intensity is achieved by excitation of the white light LED particularly weakly and particularly strongly exciting the remaining RGB diodes in the same ratio as before.
  • the color intensity can also be changed to the same extent if there is only a three-diode combination, i.e. only RGB diodes without a fourth channel. In such a case, the color intensity can be varied by using a varying part of the with the RGB diodes maximum achievable brightness is used to jointly generate a light that is perceived as neutral white.
  • a system for controlling LED lighting which comprises a dimmable LED current source in which any dimming method is implemented and a unit for automatically adjusting the color temperature of the LED lighting is provided, which has a color temperature control and driver circuit , a program and data storage circuit, an automatic programming unit and a clock circuit, wherein the automatic color temperature adjustment unit interacts with the LED power source and the program and data storage circuit maintains an information database with color temperature data over the course of the year from different geographic regions.
  • a lighting system for controlling a plurality of light sources comprising at least a first and second light source, the second light source having a higher color temperature and luminous efficiency than the second light source.
  • a controller is intended to avoid an uncomfortable feeling of turning on and off due to color mixing operations.
  • the LED power supply has first and second FET drivers and a microcontroller provides PWM signals for driving the same.
  • a light temperature change is achieved when dimming as with a light bulb.
  • a power supply for LED-based light modules is known, which are connected in parallel to a power supply.
  • a desired fixed light intensity can be specified once, for example to achieve a fixed brightness below the maximum possible brightness each time it is switched on; there may be a current desired light intensity can be preset, for example by adjustment on a switch or remote control, or a gradually changing light intensity can be set, for example to accompany a gentle awakening.
  • the U.S. 2019/00 290 931 A1 deals with an LED driving circuit with memory function for brightness and color adjustment.
  • a circuit is shown in which first and second groups of LEDs are supplied with DC voltage and an electronic switching element such as a mosfet is associated with the first and second groups of LEDs towards the common ground. The same is controlled by a microcontroller unit.
  • the object of the present invention is to provide something new for commercial use.
  • an LED DC voltage supply comprising a plurality of power channels which are designed to feed power from the same power source to LEDs of different colors; a microcontroller configured to drive power channels to result in a color temperature according to a power channel excitation ratio; and an overload protection circuit is proposed, which is further configured in such a way that the overcurrent protection circuit detects a current fed to the LEDs in total, a power fed to the LEDs in total and/or a resistance; wherein the microcontroller is configured, in response to unacceptable resistance, excess current, and/or excess power, to drive the power channels to alternately power LEDS of different colors while maintaining a color-defining excitation ratio, wherein between the power channels is alternated so rapidly that the alternation is visually imperceptible.
  • a plurality of LED power channels is generally used where a specific color impression is to be set by mixing LED colors.
  • color temperature is used in this regard, even if a total spectral emission results from the excitation of several different LEDs that are arranged close together and therefore cannot be visually separated from one another due to the small viewing angle differences certain temperature located blackbody differs.
  • the following are further relevant quantities for the description of a light emission also called brightness and color saturation.
  • the brightness is determined from the total emission intensity, whereas the saturation is determined from the proportion of colored light to "pure white" light.
  • the brightness perceived at a given power input also depends on the color temperature of the light emitted, due to the spectral sensitivity of the eye.
  • a light emission with a color that is not fully saturated is obtained if, in addition to this power part fed to the one or two selected colored LEDs in a given ratio, another power part, again the same for all three light-emitting diodes, is fed, which, in addition to the colored emission, has a pure gives a white impression, or if additional power is fed to a white LED.
  • the total brightness can - at least in the simplified case in which no different sensitivities etc. have to be taken into account, which would be easily possible through calibration - be changed by correspondingly changing the absolute total power.
  • a setting for a given color temperature, brightness and saturation can also be made for groups with four LEDs, i.e. RBG+W.
  • the powers to be fed to the LEDs to achieve a certain brightness, saturation and color temperature are determined taking into account the spectral sensitivity of the eye and non-linear light emission of the LEDs, which may not be identical from color to color. This can be accomplished through look-up tables and the like.
  • Strip-shaped carriers are often provided, along which a large number of groups of three LEDs mounted close together in the colors red, green and blue or groups of four LEDs mounted close together in the colors red, green, blue and white are arranged.
  • Different color impressions can be achieved by specifying the power fed to the respective colors of a group. It is possible to power all groups equally, so that, for example, all blue LEDs in each group are fed slightly less power than the red and green LEDs on average over time; in such a case - apart from small, production-related variations, e.g. the sensitivity of individual LEDs - the same color impression and the same brightness are also obtained on each group.
  • the respective strips can be connected to and driven by a power supply. It should be mentioned that there are other possibilities besides the power supply of LEDs on strips. It is thus possible to connect several LED lighting elements to the same power supply, even if the corresponding LEDs are not arranged on strip-shaped carriers.
  • the LED arrays will be dimmable and will be operated in dimmed mode by users.
  • a color temperature set in the dimmed state can be maintained regardless of an increase in the required power or the desired brightness without color changes occurring. This is advantageous in that the eye perceives differences in brightness essentially logarithmically (and therefore not necessarily linearly, as initially assumed), i.e. only very large differences in brightness are perceived, whereas small changes in color temperature are already noticeable. Since less energy may have to be used overall for the LED supply, to which the logarithmic character of the light intensity contributes, it is possible to save energy with the invention.
  • the arrangement according to the invention prevents the LED groups or elements of the voltage supply from being damaged.
  • the alternation is visually imperceptible where the LEDs of different colors that are spatially close together are alternately energized quickly enough in succession and with sufficient frequency. It is known from video technology that the human eye gets the impression of continuous movement from around 24 frames per second and accordingly a change between the channels will typically happen so often that each color channel to be excited is excited at least 24 times per second . In principle, it would be possible for the use of luminescent materials to give the impression that the LEDs would shine together and continuously even where there is even less frequent switching between different color channels. As a rule, however, it is preferable to switch between the color channels even more frequently.
  • this allows pulsed excitation and, where continuous or almost continuous power is not desired on all color channels, the thus possible excitation pauses to be evenly distributed, which can reduce the impression of a slightly flickering illumination; this can be advantageous not only for the human eye, but also where video recordings or photographs are to be made, on which stripe artifacts can otherwise be observed.
  • the supply voltage is kept constant and the luminous intensity is changed by completely switching the supply voltage on and off at the respective LEDs. This can happen periodically or cyclically; corresponding pulse width modulation methods are known per se. It would be possible for the microcontroller to generate its own control pulses for each LED color of an LED group, with which each LED color is controlled "on” or “off” independently of others. When the switches are implemented by transistors, no complex driver circuits are required per se, so that a comparatively simple circuit is sufficient when generating its own color control pulses. However, it is advantageous to avoid simultaneous switching of different LED colors within an LED group, since this can lead to undesirable current peaks precisely where large LED groups are present, i.e. where high power or currents may have to be switched.
  • This falling edge detection can be used to safely prevent multiple channels from receiving power simultaneously in an undesired manner; this would also be undesirable in the case of currents that are only high for a short time, because it endangers the current switching stages.
  • the advantageous edge control can also be implemented with a few logic gates, so that neither the structural complexity nor the energy required to operate the circuits are particularly large.
  • the DC voltage supply is usually designed in such a way that if the DC voltage supply is correctly adjusted, i.e. when the DC voltage supply is used with an LED strip provided for this purpose, the maximum power is output by simultaneously outputting power to LEDs of all colors. This enables flicker-free operation with a desired high brightness of a desired white light.
  • the microcontroller is designed to control power channels in such a way that when a total current that is still permissible or a power that is still permissible is called up from the same power source, power is at least partially fed simultaneously to LEDs of different colors.
  • the microcontroller is designed to do this, depending on a currently specified desired color temperature and depending on the size of the deviation of the detected current fed to the LEDs as a whole, the power fed to the LEDs as a whole and/or the total resistance of connected LEDs to the respective permissible maximum values to control power channels in such a way that power is fed to them partially simultaneously and partially alternately in the event that the permissible excess of color channels is only slight. That this is always advantageous when not all LEDs of all three (or four) colors can be excited simultaneously because this leads to an excessive current or an excessive power demand, but without exceeding a permissible maximum load at least two of three ( or three out of four or two out of four) different colors has been explained.
  • the overload protection circuit will be active during the entire operating time and will prevent excessive power or currents from being drawn from the DC voltage power pack. This makes sense because short circuits can occur as a result of defects or through carelessness on the part of users and such short circuits should be counteracted.
  • the LED DC voltage supply is designed in such a way that power is routed from the DC voltage power source to the power channels via a two-pole connection, with the overload protection circuit being designed to transmit an instantaneous total power in the first line, one to the LEDs total current fed, a total power fed to the LEDs and/or a resistance of connected, in particular total connected LEDs, and the microcontroller is designed to control through-connection of the power to the LEDs of different colors to the second line.
  • the microcontroller is designed to control through-connection of the power to the LEDs of different colors to the second line.
  • a two-pole cable is therefore sufficient and particularly advantageous where longer cables are required overall, for example in corridors and the like.
  • the power application of certain LEDs or certain LED groups can then be controlled, for example, by modulating corresponding control signals on the two lines, i.e. a broadcast-like transmission of control commands and their demodulation by local circuits specifically addressed with the broadcast.
  • an overcurrent switch such as a transistor, e.g. a P-FET transistor, can be arranged to interrupt the current flow if necessary. This is particularly advantageous because it means that all elements can be switched off simultaneously and quickly in the event of a failure.
  • a line can then be routed to all LEDs.
  • the color-dependent power control can take place in the paths to the second line, with either each color group being assigned a common second line in which a switch controlling the power application is arranged, or it is the same color for each color LED or each local plurality of LEDs a switch dedicated to the color is arranged, which controls the current flow through the color LED(s) accordingly. It is again possible to design these dedicated switches as transistors, for example as N-FET transistors.
  • dedicated channels can be controlled with the microcontroller itself.
  • the arrangement is designed in a preferred structural embodiment such that a switch-off circuit which acts jointly on all channels is provided in a first line, and the overload protection circuit is designed to activate it directly.
  • Such an arrangement is also advantageous because overcurrents or excessive power drawn can be detected easily, for example with a comparator, and a signal can be generated without great effort with which the power supply to the LEDs is direct, i.e. without additional intervention of the microcontroller, can be interrupted. This achieves a particularly fast shutdown in the event of a failure, because there is no need to jump to the interrupt routines of a microcontroller control program and then wait for the interrupt to be processed.
  • a holding element after the first response of the overload protection circuit at least maintain an off state for a specified time.
  • Such a holding element can, for example, be reset in response to a microcontroller signal and/or can be reset when it is switched on again after it has been switched off beforehand.
  • the microcontroller can also switch off all color channels as a further security measure; It is also possible to carry out a check cycle after the overload circuit has responded in order to determine whether there is an error (only) on individual channels. For this purpose, if necessary, a pulsed, preferably channel-by-channel, test power supply can take place, as in a switch-on cycle. If an error is determined on individual channels, these can be excluded from further power application. This at least allows emergency lighting at unaffected locations and/or with a color temperature that is not desired in this way.
  • a total power output or a total current fed to the LEDs is regarded as too high if certain threshold values are exceeded as a result.
  • the voltage drop across a shunt resistor can be recorded, for example; If an excessive total power output is to be avoided, the potential present between the DC voltage poles can also be taken into account, either by means of actual measurements or by assuming that certain standard values are complied with.
  • a simple comparison of the voltage drop across the shunt resistor against a permissible voltage drop is often sufficient, which is advantageous because such a simple comparison can be made with a simple comparator and does not even require digital-to-analog conversion; the comparator output can then be fed directly to the microcontroller in the typical form thanks to suitable signal levels in order to trigger an alternating feeding of power into the color channels.
  • the ability to alternately feed power from the same power source to LEDs of different colors can be achieved in a number of ways.
  • all LEDs of the same color can each be assigned a common transistor that controls their power supply. In such a case, the same color temperature is obtained with all LED groups.
  • Such control can be achieved by assigning an address to individual groups of LEDs, such as the groups near a room door, and sending control commands from the microcontroller to a local LED controller that can be reached at this address. In this way, it is possible to react dynamically to necessary local needs such as higher brightness or a different light colour.
  • the microcontroller has at least one additional sensor input and is designed to change, preferably locally, a light intensity or a light temperature in response to sensor signals received there.
  • a single motion sensor or possibly a number of motion sensors can be used to locally increase the brightness of a hotel guest walking down a particularly long, fundamentally dimly lit hotel corridor. It would also be possible with a contact sensor, in a larger cabinet arrangement with interior lighting, to illuminate more brightly those areas to which a user has just opened a door. Even with such a dynamic increase in brightness, the color temperature can be maintained without any problems, so that the dynamic increase in brightness is perceived as particularly pleasant and natural. If necessary, where a lot of power is already being used, the brightness can be slightly reduced in other places, which can easily be done by changing the on/off duty cycle. For example, during a period of less than 1/30 sec., i.e. a period that can no longer be resolved by the eye, it is very easy to cycle through all power channels very often, for example more than 10, 20 or 50 times each 1/ 30 sec. It should be mentioned that edge control is particularly advantageous for such rapid changes.
  • a dimmed illumination can then be obtained by providing excitation pauses in which none of the power channels are excited, in addition to going through power channel cycles with the channels being excited. If such excitation pauses are distributed sufficiently evenly, no flickering can be noticed.
  • An increase in the illumination intensity can then be achieved in a simple manner by reducing the number of (preferably evenly distributed and therefore short) excitation pauses at those locations at which the illumination intensity is to be increased.
  • the energizing pauses can be split, eg after energizing each LED color to pause before energizing the next LED color, or alternatively a single pause can be inserted after cycling through the LED energizing phases of all colors.
  • pauses of the same length simplify the control in terms of construction, but that pauses of different lengths can be advantageous because it enables the activation of a specific point in the achievable with a given LED arrangement Space of the HSV diagram (Hue-Saturation-Value, ie color value, saturation and brightness value) partially simplified.
  • the duty cycle can result from the HSV diagram, and with several individual colors the duty cycle can vary according to the set intensity.
  • the LED DC power supply is designed to separately drive multiple groups of LEDs of all colors. This allows a supply to be guaranteed even if simultaneous excitation of all LEDs would lead to the total currents or the total power being very significantly exceeded because the total impedance is very low. By sufficiently fast cycling through all groups, the impression of flicker-free lighting can be guaranteed for a long time.
  • overload protection circuit only needs to measure the real part of the resistance when measuring the resistance of connected LEDs, but that a complete impedance measurement including an imaginary part is also possible.
  • Protection is also claimed for a method for driving LEDs, wherein a plurality of LEDs of different colors is fed power from the same overload-protected LED power supply via a plurality of power channels and the power channels are controlled in such a way that a color temperature changes according to a power channel Excitation ratio results when detecting a total current fed to the LEDs, a total power fed to the LEDs and/or a resistance of connected LEDs for overload protection and in response to a total resistance that is too low, too much current and/or too much Overall power, the power channels are controlled in such a way that the LEDs of different colors are alternately fed with power while maintaining a color-determining excitation ratio so quickly that the alternating is not visually perceptible.
  • the extreme value is typically selected in such a way that continuous operation of the arrangement is possible without the risk of component overload, overheating and the like.
  • Exceeding is considered to be only slight if, regardless of exceeding the extreme value with simultaneous supply of all LEDs or LEDs of all colors, at least LEDs of two colors can be supplied simultaneously without a component overload or overheating is to be expected.
  • the multiplicity of LEDs of different colors is grouped into several groups and at least one group is controlled in such a way that a color temperature results that differs from the color temperature of at least one other group.
  • the signals of at least one sensor are detected and a light intensity or a light temperature is changed, preferably changed locally, in response to sensor signals received therefrom.
  • an LED DC power supply 1 has a plurality of power channels 2R, 2G, 2B adapted to supply power from the same power source 6 to LEDs 3R, 3G, 3B of different colors;
  • the LED DC voltage supply 1 also has a microcontroller 4 which is designed to control the power channels 2R, 2G, 2B in such a way that a color temperature results according to a power channel excitation ratio, as still with reference to FIG figures 2 and 3 will be explained.
  • An overload protection circuit 5 is also provided. In this case, the overload protection circuit 5 is designed to detect a total current fed to the LEDs 3R, 3G, 3B, a total power fed to the LEDs and/or a resistance of connected LEDs.
  • the microcontroller 4 is designed to drive the power channels 2R, 2G, 2B in response to a too low total resistance, too high current and/or too high total power, which are detected by the overload protection circuit and signaled to the microcontroller 4 such that to the LEDs 3R, 3G, 3B of different colors, power is alternately fed while maintaining a color-determining excitation ratio, alternating between power channels so rapidly that the alternating is visually imperceptible.
  • the LED DC voltage supply has a supply plus pole and a supply minus pole, with a shunt resistor 5A and a power-switching transistor 5E terminating the current flow in the event of an overload being provided in the supply line from the plus pole to the LEDs. So the current for all colored LEDs that receive power from power source 6 flows through this shunt resistor.
  • the LEDs are connected in such a way that the anodes of all LEDs are connected in parallel to the same line behind the power-switching transistor 5E.
  • the LEDs 3R, 3G, 3B of different colors include red, green and blue LEDs.
  • the microcontroller has 3 control outputs 4R, 4G, 4B, which can be connected via corresponding lines 8R, 8G, 8B - and, if necessary, via respective driver circuits (not shown) - are led to respective power switching transistors 7R, 7G, 7B.
  • These power switching transistors 7R, 7G, 7B are each arranged in series with their associated LEDs, i. H.
  • the power switching transistor 7R in series with the red LED 3R; the power switching transistor 7G in series with the green LED 3G; and the power switching transistor 7B in series with the blue LED 3B.
  • the currents that may be switched through by the power transistors and that flow through the LEDs are collected on the line connected to the minus pole.
  • each LED has its own power-switching transistor 7R, 7G, 7B.
  • the power for multiple red LEDs 3R be switched via one and the same power switching transistor 7R; power for multiple green LEDs 3G can be switched through one and the same power switching transistor 7G and power for multiple blue LEDs 3B can be switched through one and the same power switching transistor 7B. Therefore, in a typical implementation, LEDs are arranged in groups of 3 LEDs each (one red, one green and one blue) and then several such groups are distributed along a strip-shaped carrier and connected in parallel to each other. Where this is the case and only one power switch per color is to be used, the power switching transistors 7R, 7G, 7B can be connected directly to the DC power supply 1, i. H.
  • the light-emitting surfaces of the red, green, and blue LEDs in a group are so close together that they cannot be visually separated; Simultaneous excitation of the 3 LEDs gives the impression of a uniform luminous surface, with the The color with which the surface lights up is determined by the intensities with which each individual LED lights up.
  • the DC voltage source 6 is designed to feed current to a specific number of LEDs simultaneously. If the number of connected LEDs is greater than that specified by the design of the DC voltage source 6, then the DC voltage source 6 will be overloaded if an attempt is nevertheless made to simultaneously feed current to this excessive number of LEDs.
  • the connections of the DC voltage supply are now designed in such a way that any number of LEDs can be electrically connected to the DC voltage supply. This is the case, for example, where a large number of RGB LED groups are arranged equidistantly along a carrier strip and red, green and blue LEDs are each electrically connected in parallel to three dedicated power supply lines and terminals or always the same socket/plug combinations for connection of the LED strips are used. If too long a leadframe is then connected to the DC power supply, there will be too many red LEDs to be powered electrically in parallel, as well as too many green LEDs and too many blue LEDs.
  • the maximum load monitor 5 is arranged to counteract an overload.
  • the maximum load monitoring includes a 5A shunt resistor in the supply line, which leads from the positive pole of the DC voltage source to the anodes of the LEDs.
  • the voltage drop across the shunt resistor 5A is fed to a comparator 5B and compared there with a maximum permissible voltage drop.
  • the analog current is thus recorded in a simple manner without prior digitization, i.e. an analog measurement is carried out, so to speak.
  • the comparator 5B outputs a first binary level, e.g. 5V, when the voltage drop across the shunt resistor 5A is not greater than the maximum permissible voltage drop, whereas the comparator 5B outputs a second level, e.g.
  • the comparator 5B has a holding element in order to hold the second signal level even after the maximum permissible voltage drop across the shunt resistor has been briefly exceeded, until a reset signal is received from the microcontroller 4 via a line 5D.
  • the output of the comparator 5B is first fed to a driver circuit 5C, with which a power transistor 5E is switched on as long as the first level is signaled by the comparator and, in the exemplary embodiment shown, on a further line 5G by the microcontroller via a corresponding digital signal that power can in principle be output to the LEDs (for example after an initialization has been completed), whereas the power transistor 5E is switched off as soon as the comparator outputs the second level or the microcontroller does not output an enabling signal on line 5G.
  • the switching process by the comparator 5B with which a change is made from the first level to the second level indicating a critical state, takes place so quickly that no damage occurs to any of the circuit elements due to overloading until the power transistor is switched off.
  • the arrangement can be designed in such a way that the second line is optional is, ie an additional signal line from the microcontroller to the driver circuit can be dispensed with.
  • the output of the comparator 5B is also fed to an input of the microcontroller 4, so that the microcontroller has information about whether or not a permissible maximum load is currently being exceeded.
  • a memory is assigned to the microcontroller, in which memory a control program is stored for the microcontroller, the execution of which leads to operation of the arrangement according to the invention.
  • the arrangement is used as follows: First, an LED strip is connected to the DC voltage source and the arrangement is switched on. For the sake of explanation, let the LED strip carry a permissible number of LEDs which can still be supplied with power simultaneously from the DC voltage source and which are not defective.
  • An initialization cycle is then carried out first, in which the comparator first receives a reset signal via line 5D, so that the driver circuit 5C switches the power transistor 5E on. Thereafter, a first short power pulse is fed to the red LEDs, and only to these, in that the power transistor 7R is switched on by the microcontroller 4 via line 2R.
  • the initialization cycle described requires only a short time.
  • the excitation pulses applied for each test are so short that even in the event of failure the most sensitive components in the circuit are not destroyed; At the same time, the excitation pulses are so long that in the event of failure or when a mismatched LED strip with too many LEDs is connected, the overload condition is reliably detected by the comparator and a corresponding output signal is generated by the comparator.
  • a color in the single excitation mode is already determined to be in an overload condition, checks are no longer made to determine whether an overload condition also occurs when excitation in pairs with this color switched on; on the contrary, it is clear that a color for which an overload case already occurs in the single excitation mode must not be excited together with other colors. In the same way, it is clear that where an overload is already observed in at least one pairwise combination, there is no need to check for overload-free simultaneous excitability of all three colors.
  • the LED DC power supply that is turned on is ready to power the LEDs.
  • a white illumination with maximum intensity is first called up via a remote control and a suitable interface of a remote control signal receiver to the microcontroller 4 (neither shown).
  • White illumination is obtained when all LEDs are energized with equal power; maximum intensity is obtained when all LEDs continuously receive an excitation signal. Accordingly, the microcontroller emits a signal on all 3 lines 8R, 8G, 8B, which switches on the power transistors 7R, 7G, 7B assigned to the colors red, green and blue, so that current flows through all 3 LEDs. As previously clarified, no overload occurs with this simultaneous excitation of all LEDs.
  • the voltage drop across the shunt resistor 5A is so low that the voltage comparator 5B does not respond and the power switching transistor 5E, which is assigned to all LEDs, can remain conductive in the connecting line between the positive pole and the LED anode.
  • the red LED is again continuously energized, while the blue and green LEDs are pulsed. Power may be fed to all LEDs at the same time.
  • the exact shade of red desired can be set by energizing the green and blue LEDs for different times. An admixture of some more blue light is obtained by the excitation phases for the blue LEDs are longer than the excitation phases for the green LEDs. Conversely, more green light can be mixed in by making the excitation phases of the green LEDs longer than those of the blue LEDs.
  • the intensity of the red color can be adjusted by changing the pause times for green and blue LEDs; shortening the pause times leads to a less intense staining.
  • the ratio of on/off times can be reduced in the same way for all LED colors. This is consistent reddish color in the case of a low intensity desired by the user Figure 2-D shown. It should be noted that there are still times when all three LEDs are energized simultaneously. This is not mandatory, but it is particularly easy to implement in terms of circuitry.
  • the overload protection determines, in view of the previous excitation pattern with simultaneous excitation of all colors, that the voltage drop across the shunt resistor is greater than permissible, i.e. that the currents are too high to ensure permanent, safe operation make possible. Accordingly, the comparator signal will change from the first to the second level, which switches the power transistor 5E off and at the same time signals the microcontroller 4 that an overload case has occurred.
  • the microcontroller 4 will then end the generation of excitation pulses for the power transistors 7R, 7G and 7B, then reset the comparator 5B and, in a test cycle as in the initialization of the system after switching on, first check whether all LED colors may still be excited individually. For this purpose, a short, testing excitation pulse is first output only to excite the red LEDs for transistor 7R; the comparator 5B will not respond in this case, since despite the excessive length that has resulted from the use of the additional LED strip, there is still no case of overload with single excitation. Equal results are obtained using short excitation pulses to excite only the green LEDs and then only the blue LEDs.
  • the extended LED strip arrangement can only be operated if each color channel is excited individually. It is pointed out that the LEDs of different basic colors must be operated in a pulsed manner to achieve a given color and therefore the individual LEDs of the overall arrangement will shine less brightly on average than in cases in which, thanks to correct adjustment of the LED strip to the available power supply a permanent excitation of the LED is possible.
  • a short pulse is first provided by the microprocessor, with which the power transistor 7R is switched on. After the termination of this pulse, the LED 3G is energized for the same time, and after the termination of the energization of the light emitting diode 3G, the blue LED 3B is energized.
  • the microcontroller could repeatedly generate individual excitation pulses and directly control the corresponding power transistors 7R, 7G and 7B accordingly.
  • this means a comparatively high level of control expenditure it is possible—without requiring greater expenditure on the microcontroller 4—to cycle through the individual colors only slowly, which is disadvantageous because the color change may then be more noticeable.
  • the present invention achieves synchronization of the color sequence without great effort in such a way that LEDs of a color to be subsequently excited are only switched on after the LEDs of the previously excited color are switched off. Structurally, this can be implemented without problems and with extremely little effort by waiting before switching on the excitation power for LEDs of another color until a falling edge is detected in the excitation power or the excitation current for the LEDs of the previously excited color. Such a detection is possible with simple logic gates.
  • a pulse count value is also possible to store a pulse count value once for each color channel, which indicates how many (possibly frequency-multiplied) clock pulses an LED of a given color is energized for, until the excitation is terminated.
  • a pulse counter value must be stored only once in a register or the like for each LED color as long as the illumination requested by the user does not change, ie neither color temperature nor intensity nor color shade are changed; after that, the microcontroller is no longer needed to cycle through the LED sequence. Rather, the next color can be switched to active upon detection of the falling edge of the previous excitation pulse, i. H.
  • a corresponding signal can be sent to the power transistors 7 or the driver circuit provided for them, similar to the transistor 5E controlling the total power receiving a signal from the comparator 5B allowing or preventing the conduction of current.
  • the falling edge can be detected for the next LED to be excited and the process repeated for the next LED color to be excited.
  • an on/off duty cycle can then be calculated in each case, which is obtained for all Led colors by multiplying by the same factor, but given the differences from Led color to Led colour Lighting durations with pure white light lead to different lengths of lighting breaks for the different colors.
  • the cycling between the individual colors can also then take place very quickly without great effort, in particular without great effort with regard to the microcontroller after the adjustment has been made.
  • the procedure described also enables a very rapid, dynamic change in the intensity and/or color of the light generated with an overall LED arrangement or the light generated in different groups in each case with different groups;
  • the microcontroller is essentially only required to feed on/off counter values into corresponding (local) registers until the operating parameters change, and no bandwidth-intensive control signals are required.
  • the dynamic change in light thus preferably only requires a change in the respective locally stored register values, which also takes place quickly.
  • there is no need for an interruption in the lighting if the stored register values can remain valid until they change thanks to edge detection, in which case, in particular, the count values stored in the individual registers can be changed successively.
  • This possibility of rapid changes makes the invention particularly suitable for reacting dynamically to changed requirements, for example to react to sensor signals such as motion detectors, buttons, door contacts, temperature sensors, etc., especially if areas that are to be illuminated more brightly have been defined beforehand.
  • the impedance or a characteristic value of the connected LEDs can be determined by color and/or group by color and then it can be determined, for example, by calculation which LED (groups ) can be operated simultaneously. It is clear that channel groups can be preselected more precisely for alternating operation, in particular when the load is known, and power can be distributed accordingly; it can then be better guaranteed, for example, that changes in intensity and/or color are only permitted to the extent that no overload occurs.
  • the current flowing through the LEDs can also be digitized if necessary and the digitized current values can be used to determine permissible operating parameters instead of just carrying out a simple analog measurement using a comparator comparison .
  • a data line 5h is shown for this option, with which the corresponding digitized current values can be transmitted to the microcontroller. It should be mentioned that this is not mandatory but optional.
  • the impedance can also be determined with one or more low measuring voltages, which are fed to the respective LED or LED groups to be tested, by determining whether a specific current is exceeded in each case or not. If the currents occurring across the shunt resistor are detected with one or the comparator when the measuring voltage is applied, or when it is detected whether a specific threshold is not exceeded when the measuring voltage is applied, the measuring voltage only needs to be provided with very low power; in terms of circuitry, this is therefore simple.

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  • Circuit Arrangement For Electric Light Sources In General (AREA)
EP22020456.4A 2021-09-24 2022-09-23 Alimentation de puissance à del Pending EP4156864A1 (fr)

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DE102021004829 2021-09-24
DE102021005158.0A DE102021005158A1 (de) 2021-09-24 2021-10-15 LED-Leistungsversorgung

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Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080315780A1 (en) * 2007-06-20 2008-12-25 Samsung Electro-Mechanics Co., Ltd. Light emitting diode driving device
DE102008029816A1 (de) 2008-06-24 2009-12-31 Osram Gesellschaft mit beschränkter Haftung Schaltung zur Dimmung einer Lampe und zugehöriges Verfahren
EP2592903A2 (fr) 2011-11-08 2013-05-15 Panasonic Corporation Sytsteme d'èclairage et luminaire
US8736183B2 (en) 2012-04-10 2014-05-27 Wen-Shin Chao LED driver capable of controlling color/color temperature with a power carrier
US20150145431A1 (en) 2013-11-27 2015-05-28 Lumenetix, Inc. Voltage-controlled dimming of led-based light modules coupled in parallel to a power supply
US20160157318A1 (en) * 2014-12-01 2016-06-02 Hubbell Incorporated Current Splitter For Led Lighting System
US10009974B2 (en) 2016-04-09 2018-06-26 Tempo Industries, Llc Dim to warm LED lighting system
US10159131B1 (en) 2018-03-26 2018-12-18 Adam Chaimberg Dimmable LED light fixture maintaining brightness during color temperature change
US20190290931A1 (en) 2016-06-14 2019-09-26 Koninklijke Philips N.V. Robust broad beam optimization for proton therapy
DE202020101445U1 (de) 2020-03-16 2020-05-19 Cvitec Gmbh System zur intelligenten Anpassung der Farbtemperatur einer LED-Beleuchtung

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080315780A1 (en) * 2007-06-20 2008-12-25 Samsung Electro-Mechanics Co., Ltd. Light emitting diode driving device
DE102008029816A1 (de) 2008-06-24 2009-12-31 Osram Gesellschaft mit beschränkter Haftung Schaltung zur Dimmung einer Lampe und zugehöriges Verfahren
EP2592903A2 (fr) 2011-11-08 2013-05-15 Panasonic Corporation Sytsteme d'èclairage et luminaire
US8736183B2 (en) 2012-04-10 2014-05-27 Wen-Shin Chao LED driver capable of controlling color/color temperature with a power carrier
US20150145431A1 (en) 2013-11-27 2015-05-28 Lumenetix, Inc. Voltage-controlled dimming of led-based light modules coupled in parallel to a power supply
US20160157318A1 (en) * 2014-12-01 2016-06-02 Hubbell Incorporated Current Splitter For Led Lighting System
US10009974B2 (en) 2016-04-09 2018-06-26 Tempo Industries, Llc Dim to warm LED lighting system
US20190290931A1 (en) 2016-06-14 2019-09-26 Koninklijke Philips N.V. Robust broad beam optimization for proton therapy
US10159131B1 (en) 2018-03-26 2018-12-18 Adam Chaimberg Dimmable LED light fixture maintaining brightness during color temperature change
DE202020101445U1 (de) 2020-03-16 2020-05-19 Cvitec Gmbh System zur intelligenten Anpassung der Farbtemperatur einer LED-Beleuchtung

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