LED POWER SUPPLY

Description

[0001] The present invention relates to what is claimed in the preamble and accordingly relates to the power supply of LEDs.

[0002] Light-emitting diodes are increasingly being used for lighting purposes. These light-emitting diodes are often powered by a DC power supply with a given output power, which not only allows the user to enjoy energy-saving lighting but also offers a wide range of customization options. For example, a user will typically desire light that is generally perceived as white or colored light. White light is obtained by arranging and energizing light-emitting diodes of different colors, such as red, green, and blue light-emitting diodes, closely arranged. The light temperature, i.e., the "color" of the emitted light, can be adjusted by supplying power to the red, green, and blue LEDs in different ratios depending on the color.However, assuming a linear relationship between excitation power, light emission, and brightness perception, the overall brightness of the emitted light can be changed by increasing the power supplied to the diodes equally for all light-emitting diodes; for example, doubling the excitation power results in lighting that is perceived as twice as bright. (For the sake of accuracy, it should be noted that the assumption of a strictly linear relationship between excitation power, light emission, and brightness perception is a simplification made for ease of explanation, but a different relationship may occur in practice, which may need to be taken into account by appropriate measures.)

[0003] Thus, the brightness can be adjusted, i.e., dimmed, by changing the LED supply voltage uniformly for all diodes. It is also possible to provide a so-called white-light LED, which emits a light perceived as "white" with a fixed color temperature of, for example, 5500° Kelvin. A change in the excitation power supplied to this so-called white-light LED merely results in a change in brightness. (It should be noted that even such an LED does not usually produce the exact spectrum of a blackbody radiator at the specified temperature. Nevertheless, for the sake of clarity, reference is made here to a "color temperature.")

[0004] Furthermore, it is possible to change the color intensity, i.e., to adjust whether the emitted light exhibits only a very slight deviation from a given color temperature or whether this color deviation results in a coloration perceived as very intense or "poppy." With a combination of four RGB+W LEDs, this intensity can be changed by energizing the white light LED particularly strongly for a low color intensity, while energizing the RGB color diodes overall at a lower ratio to each other, as required for the desired color temperature. Conversely, high color intensity is achieved by energizing the white light LED very weakly and energizing the remaining RGB diodes particularly strongly in the same ratio as before. The color intensity can also be changed to the same extent with only a three-diode combination, i.e., with only RGB diodes without a fourth channel.In such a case, the color intensity can be varied by using a varying part of the maximum brightness achievable with the RGB diodes to create a light that is perceived as neutral white.

[0005] Especially where it is considered particularly advantageous and desirable to be able to make such adjustments to brightness, color temperature and intensity, it is often desired that a certain characteristic is actually guaranteed.

[0006] Therefore, a large number of circuits have already been proposed that deal with the power supply of LEDs.

[0007] DE 10 2008 0 29816 A1 discloses a circuit for dimming a lamp and a corresponding method. It is stated that adjusting the color temperature of LEDs is difficult for customers due to the required adjustment of three individual controls, particularly when selecting the color temperature depending on the lamp's brightness. The document aims to specify a lamp whose color temperature shifts toward warmer color temperatures as the power is reduced, similar to an incandescent lamp.

[0008] From DE 20 2020 101 445 U1 a system for controlling LED lighting is known, which comprises a dimmable LED power source in which any dimming method is implemented and a unit for automatically adjusting the color temperature of the LED lighting is provided, which unit has a color temperature control and driver circuit, a program and data storage circuit, an automatic programming unit and a clock circuit, wherein the unit for automatically adjusting the color temperature 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 geographical regions.

[0009] EP 2 592 903 A2 discloses a lighting system for controlling a plurality of light sources, each comprising at least a first and a second light source, wherein the second light source has a higher color temperature and luminous efficiency than the second light source. Such a control system is intended to prevent an unpleasant feeling when switching on and off due to color mixing operations.

[0010] From US 8 736 183 B2 a method is known in which a dimmer changes an output current to change the power of an LED in such a way that a stable light is obtained, but color temperature deviations and flickering are supposedly avoided.

[0011] US 10 009 974 B2 discloses an arrangement in which the LED power supply has first and second FET drivers, and a microcontroller provides PWM signals to control them. Among other things, the aim is to achieve a light temperature change during dimming, similar to that of a light bulb.

[0012] US 10 159 131 B1 discloses a dimming arrangement for LEDs that is intended to retain their brightness when the color temperature changes.

[0013] US 2015 / 0145431 A1 discloses a power supply for LED-based lighting modules that are connected in parallel to a power supply. For dimming, a desired fixed light intensity can be set once, for example, to achieve a fixed brightness below the maximum possible brightness each time the light is switched on. If necessary, a currently desired light intensity can be set, for example, by setting a switch or remote control, or a gradually changing light intensity can be set, for example, to accompany a gentle awakening.

[0014] US 2019 / 00 290 931 A1 deals with an LED control circuit with a memory function for brightness and color tuning. It shows a circuit in which first and second LED groups are supplied with DC voltage and an electronic switching element such as a MOSFET is assigned to the first and second LED groups to the common ground. These are controlled via a microcontroller unit.

[0015] US 2011 / 0234113 A1 describes an LED controller that can supply power to different LEDs by switching on power via a PWM controller. The controller can supply the different LEDs alternately. The current, which is supplied via a constant current source, is always divided.

[0016] US 2013 / 0015774 A1 discloses an LED power supply that features a voltage converter for powering multiple LED channels. The LED channels can be selectively supplied with current, while maintaining a constant total current.

[0017] US 2016 / 157318 A1 discloses a control method and a control device for LEDs that uses a dimmable LED driver circuit whose current output is split. The splitting is to occur independently of the driver's output and is based at least partially on a variable reference signal.

[0018] From DE 20 2013 004095 Ul a lighting system with two or more light-emitting diodes and a common power supply unit is known, wherein the two or more light-emitting diodes are arranged in at least two current paths and the power supply unit is designed to divide a total electrical power between the at least two current paths in a control parameter.

[0019] US 2008 / 315780 A1 discloses a control device for an LED array that includes a DC-DC converter whose current can be switched. The array's LEDs thus receive input voltages of varying magnitudes and can also be switched on and off according to a duty cycle. In the event of an overcurrent fault, the duty cycle is to be reduced to zero.

[0020] In the private sector, despite the known arrangements, the problem still arises that not only should adjustments be possible in a simple manner, but that there is often also a mismatch between LEDs and the power supply unit. For example, because a purchased, initially sufficient power supply unit is then supposed to power additional LEDs after some time and is therefore automatically overloaded. It should be mentioned that overloading can have various effects. In the case of only a slight overload, i.e., only a slightly too low impedance in the connected LEDs, it is possible that only the supply voltage collapses without significant damage to components. If the impedance falls significantly below the intended impedance or the power supply is massively overloaded, damage to connected components or the power supply itself can occur.

[0021] The object of the present invention is to provide something new for industrial application.

[0022] The solution to this problem is claimed independently. Some of the preferred embodiments are found in the subclaims.

[0023] According to a first basic idea, an LED DC voltage supply is proposed, comprising a plurality of power channels configured to supply power from the same power source to LEDs of different colors; a microcontroller configured to control power channels such that a color temperature results according to a power channel excitation ratio; and an overload protection circuit, which is further configured such that the overcurrent protection circuit detects a total current supplied to the LEDs, a total power supplied to the LEDs, and / or a resistance.wherein the microcontroller is designed, in response to an unacceptable resistance, an excessive current and / or an excessive total power, to control the power channels in such a way that power is supplied alternately to the LEDs of different colors while maintaining a color-determining excitation ratio, wherein the alternating between the power channels is so fast that the alternating is not visually perceptible;

[0024] A plurality of LED power channels is typically used where a specific color impression is to be achieved by mixing LED colors. In this application, this term is used for color temperature, even if the excitation of several different LEDs arranged closely together and thus visually inseparable due to the small differences in viewing angle results in a total spectral emission that differs from the emission of a black body at a specific temperature. For the sake of completeness, brightness and color saturation are also mentioned as further relevant quantities for describing light emission. Brightness is determined by the total emission intensity, whereas saturation is determined by the proportion of colored light to "pure white" light.For the sake of accuracy, it should also be noted that the brightness perceived at a given power input also depends on the color temperature of the emitted light due to the spectral sensitivity of the eye.

[0025] For the purposes of this description, it can be assumed that if the same power is supplied to all three LEDs in an LED group comprising one red, one green, and one blue LED, the light emitted will give the impression of pure white. A fully saturated color with a specific color temperature can be achieved in a simplified manner by supplying power to just one of three colored diodes, with the desired color temperature determining which individual diode(s) should be excited and the power(s) this diode(s) receives. Light emission with a color that is not fully saturated is obtained if, in addition to this power supply supplied to the one or two selected colored LEDs in a given ratio, a further power supply, the same for all three light-emitting diodes, is supplied, which, in addition to the colored emission, produces a pure white impression.when additional power is supplied to a white LED. The overall brightness can be adjusted—at least in the simplified case where different sensitivities, etc., do not need to be taken into account, which would be easily possible through calibration—by adjusting the absolute total power accordingly. Similarly, for groups of four LEDs, i.e., RGB+W, an adjustment can be made for a given color temperature, brightness, and saturation.

[0026] It is possible that in a real implementation, the power required to achieve a specific brightness, saturation, and color temperature would be determined by taking into account the spectral sensitivity of the eye and the nonlinear, possibly non-identical light emission of the LEDs from color to color. This can be achieved using lookup tables and the like.

[0027] Often, strip-shaped supports are provided, along which a large number of groups of three closely mounted LEDs in the colors red, green, and blue, or groups of four closely mounted LEDs in the colors red, green, blue, and white, are arranged. By specifying the power supplied to the respective colors of a group, different color impressions can be achieved. It is possible to supply all groups with power in the same way, so that, for example, all blue LEDs in each group are supplied, on average, slightly less power than the red and green LEDs. In such a case, apart from minor, production-related variations, z.B. the sensitivity of individual LEDs - the same color impression and brightness can be achieved in each group. Alternatively, it is possible to supply specific areas along the strip in different ways, for example, to make selected areas shine brighter or in different colors. The corresponding strips can be connected to a power supply and controlled by it. It should be mentioned that there are other options besides supplying power to LEDs on strips. For example, it is possible to connect several LED luminaires to the same power supply, even if the corresponding LEDs are not arranged on strip-shaped supports.

[0028] Nevertheless, the following will explain some of the details using LED strips as an example, since such a structural design is particularly relevant in the home, and mismatches often occur in this context, for example, when longer, possibly chained, carrier strips are fed from an undersized power supply. The invention is particularly advantageous in such an environment because potential mismatches are encountered particularly frequently. In commercial installations, especially newly planned installations, it is more likely that mismatches will not occur.

[0029] This makes it possible to ensure optimal power supply to the consumers up to the limit of the maximum possible power demand, which is usually the power limit of the DC voltage supply, without the user noticing the mismatch. In many cases, the LED arrays will be dimmable and can also be operated dimmed by the user. A color temperature set in a dimmed state can be maintained regardless of an increase in the requested power or the desired brightness, without any color changes occurring. This is advantageous in that the human eye essentially perceives differences in brightness in a logarithmic manner (and thus not necessarily linearly, as initially assumed), meaning that only quite large differences in brightness are perceived, whereas even small changes in color temperature are very noticeable.Since less energy may be required overall for the LED supply, which is helped by the logarithmic nature of the light intensity, it is possible to save energy with the invention.

[0030] At the same time, the arrangement according to the invention prevents damage to the LED groups or to elements of the power supply.

[0031] The alternation is not visually perceptible where the closely spaced LEDs of different colors are energized quickly enough one after the other and with sufficient frequency. It is known from video technology that the human eye receives the impression of continuous movement from around 24 frames per second onwards, and accordingly, a change between channels will typically occur so frequently that each color channel to be excited is energized at least 24 times per second. In principle, it would be possible to use luminescent materials to create the impression that the LEDs are glowing together and continuously, even where switching between different color channels occurs even less frequently. As a rule, however, it is preferable to switch between the color channels even more frequently.This allows, in particular, pulsed excitation and, where continuous or almost continuous power is not desired on all color channels, the possible excitation pauses can be evenly distributed, which can reduce the impression of slightly flickering lighting; this can be advantageous not only for the human eye, but also where, for example, video recordings or photographs are to be made, on which stripe artifacts would otherwise be observed.

[0032] It should be noted that rapid alternation between the power channels while maintaining a color-determining excitation ratio might also be possible where the LEDs are supplied with alternating current, or a direct current with a (preferably periodically) varying voltage is provided. In such a case, however, maintaining a constant color temperature requires these fluctuating voltages to be taken into account when applying power to the individual LED groups. This requires additional effort in terms of the microcontroller's firmware and software, and also makes the recording of an instantaneous voltage useful.Even if this entails greater construction complexity and, insofar as the implementation of the invention with DC power supplies is considered to be of significantly greater economic importance, it should be noted that the applicant reserves the right to claim the invention even if the LEDs are supplied with periodically or aperiodically fluctuating voltages. As mentioned, a current voltage can then be detected, and the excitation of different color channels required according to a current voltage can be time-controlled according to the excitation voltage-luminous intensity behavior of the different channels in such a way that the impression of a constant color temperature is maintained through controlled excitation within a sufficiently short time, such as a thirtieth of a second, compared to the inertia of the eye.

[0033] In a particularly preferred variant, the supply voltage is kept constant and the luminous intensity is varied by switching the supply voltage to the respective LEDs completely on and off. This can be done periodically or cyclically; corresponding pulse-width modulation methods are known per se. It would be possible for the microcontroller to generate separate control pulses for each LED color in an LED group, with which each LED color is controlled "on" or "off" independently of others. Implementing the switches using transistors per se also eliminates the need for complex driver circuits, so a comparatively simple circuit is sufficient for generating separate color control pulses. However, it is advantageous to avoid simultaneous switching of different LED colors within an LED group, as this can be particularly problematic where large LED groups are present, i.e., where high power or high energy consumption may be required.Currents that have to be switched can lead to unwanted current spikes. In this case, it is advantageous to avoid such spikes associated with switching operations. In addition, when generating separate control pulses, care must be taken to ensure that these do not coincide at some point due to various effects such as the gradual thermal runaway of phase-locked loops and the like. It is therefore proposed that, at least when channels are not to be excited simultaneously, a switch-off edge of a first channel to be operated is detected and a second channel is only activated upon detection of this switch-off edge. Depending on the edge steepness, a slight time delay after detection of the switch-off edge before the second channel is activated can even be implemented.This falling-edge detection reliably prevents multiple channels from receiving undesired current simultaneously; this would be undesirable even with only short-term high currents, as it would endanger the current switching stages. Furthermore, the advantageous edge control can be implemented with just a few logic gates, so neither the construction effort nor the power required to operate the circuits are particularly high.

[0034] This not only achieves a simple and fail-safe implementation, but also ensures high immunity to unstable clock generators (jitter). A particularly simple edge control of all colors can be implemented if the activation pulses always pass through all colors in the same order; then, by simply counting each LED color, it can be determined whether the LED should currently be energized.It should be noted, however, that with certain very intense colors, it may not be possible to achieve full performance unless measures are taken that allow, for example, the simultaneous excitation of two channels and separate excitation of a third channel; this is always useful when two, but not three, color channels can be controlled simultaneously, i.e., when there is a comparatively low overload, for example because a user has connected only a few too many LED groups to an existing power supply.

[0035] Since particularly strong, "pure" colors are rarely used, and even when desired, they are rarely used with particularly high intensity, especially in a home environment, a corresponding circuit for such mixed parallel-simultaneous control can certainly be useful. Nevertheless, it should be noted that simple logic circuits are sufficient to enable simultaneous excitation of two channels and separate excitation of a third channel, if necessary.

[0036] The DC power supply is designed so that, when correctly matched—i.e., when used with a dedicated LED strip—maximum power is delivered by simultaneously delivering power to LEDs of all colors. This enables flicker-free operation with the desired high brightness and white light.

[0037] However, such simultaneous excitation is deviated from as soon as critical loads arise from simultaneous excitation of more than two instead of all three or more than three of four LED colours.

[0038] Furthermore, it should be mentioned that it is perfectly possible to operate a DC power supply in such a way that the LEDs in different color channels cycle, even when a load no larger than the intended one is connected. However, to enable operation with mismatched LED arrangements in such a DC power supply, which essentially circulates between color channels, by distributing the available output current or output power across different channels, the use of addressable groups would be necessary to prevent all LEDs of the same color from simultaneously drawing excessive current due to the mismatch.

[0039] It is therefore advantageous if, in an LED DC voltage supply, the microcontroller is designed to control power channels in such a way that when a still permissible total current or a still permissible power is called up from the same power source, power is at least partially supplied to LEDs of different colors simultaneously.

[0040] It should be mentioned in this regard that it is possible and preferred if the microcontroller is designed to control power channels depending on a currently specified color target temperature and depending on the magnitude of the deviation of the detected total current supplied to the LEDs, the total power supplied to the LEDs and / or the total resistance of the connected LEDs from the respective permissible maximum values ​​in such a way that, in the event of only a slight exceedance of the permissible values, power is supplied to them partially simultaneously and partially alternately. It has been explained that this is always advantageous when not all LEDs of all three (or four) colors can be excited simultaneously, because this would lead to excessive current or excessive power consumption, but at least LEDs with two of three (or three of four, or two of four) different colors can be excited without exceeding a permissible maximum load.

[0041] In a preferred embodiment, the overload protection circuit will be active throughout the entire operating period and prevent excessive power or current from being drawn from the DC power supply. This is sensible because short circuits can occur due to defects or user negligence, and such short circuits should be prevented.

[0042] It is particularly advantageous if the LED DC voltage supply is designed such that power is fed from the DC voltage power source into the power channels via a two-pole connection, wherein the overload protection circuit is configured to detect, in the first line, an instantaneous total power, a total current supplied to the LEDs, a total power supplied to the LEDs, and / or a resistance of connected LEDs, in particular all connected LEDs, and the microcontroller is configured to control the switching of the power to the LEDs of different colors to the second line. A common switch is then connected in series in one line, and several parallel switches, each for one LED color, are present in the current paths leading through the LEDs to the opposite pole.A two-pole cable is therefore sufficient and particularly advantageous where longer cables are required, for example in corridors and the like.

[0043] The control of the power supply to certain LEDs or certain LED groups can then be achieved, for example, by modulating corresponding control signals onto the two lines, i.e. a broadcast-like transmission of control commands and their demodulation by local circuits specifically addressed with the broadcast.

[0044] It is possible to first measure the total current through a section of line, for example, using a shunt resistor. An overcurrent switch, such as a transistor (e.g., a P-FET transistor), can then be placed behind the shunt resistor, which is used to determine the total power or current, to interrupt the current flow if necessary. This is particularly advantageous because it allows all elements to be de-energized simultaneously and quickly in the event of a failure.

[0045] A single line can then be routed to all LEDs. Color-dependent power control can occur 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 supply is located, or a color-dedicated switch is located for each color LED or each local plurality of LEDs of the same color, which controls the current flow through the color LED(s) accordingly. Again, these dedicated switches can be implemented as transistors, for example, as N-FET transistors.

[0046] Alternatively, channels can be controlled specifically using the microcontroller itself.

[0047] From the above, it can be seen that in a preferred structural embodiment, the arrangement is designed such that a shutdown circuit acting jointly on all channels is provided in a first line, and the overload protection circuit is designed to control this circuit directly. Such an arrangement is also advantageous because overcurrents or excessively high power consumption 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 can be interrupted immediately, i.e., without additional intervention by the microcontroller. This achieves 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.Since the signal levels and currents available from conventional comparator components can often be used to directly change the conduction state of a switch such as a P FET transistor, the construction effort is also extremely low. It is possible to provide a latch to maintain a switch-off state for at least a certain period of time after the overload protection circuit has initially responded. Such a latch can be reset, for example, in response to a microcontroller signal and / or upon restarting the device after a previous switch-off.

[0048] It should be noted that, if necessary, the microcontroller can also shut down all color channels as an additional safety measure. It is also possible to perform a control cycle after the overload circuit has been triggered to determine whether a fault exists (only) on individual channels. For this purpose, a pulsed, preferably channel-by-channel test power supply can be performed, as in a power-on cycle. If a fault is detected on individual channels, these channels can be excluded from further power supply. This at least allows emergency lighting to be provided in unaffected areas and / or with an undesirable color temperature.

[0049] If an apparent or actual short circuit or overload is detected, all channels can be briefly tested one after the other. If necessary, emergency lighting can then be implemented using at least the channels that are still functioning.

[0050] It should be noted that it is not necessary to detect a mismatch in a multi-color LED array that requires power, such as an overly long LED strip, only when excessive current is being drawn, which could potentially be damaging to the components. Rather, it is advantageous to perform one or more resistance measurements during initialization, for example, when commissioning the DC power supply. These measurements can be used to determine, for example, whether the connected LEDs have an overall impedance that is too low to be supplied with a high power supply together.In such a case, it is possible to apply a lower test voltage than required for operation and / or to feed individual excitation pulses to the color channels that are so short that damage to particularly sensitive components, such as power-switching transistors, is not yet a concern. Single-channel-based initialization in particular allows for a clear detection of any anticipated overall overload.

[0051] The total power delivered or the total current supplied to the LEDs is considered too high if it exceeds certain thresholds. To determine this, for example, the voltage drop across a shunt resistor can be measured. To prevent excessive total power delivered, the potential between the DC voltage poles can also be taken into account, either by measuring the current or by assuming that certain standard values ​​are maintained.Therefore, 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 easily performed with a simple comparator and does not even require digital-to-analog conversion; the comparator output can then, in typical configurations, be fed directly to the microcontroller thanks to suitable signal levels to trigger an alternating supply of power to the color channels.

[0052] There are different ways to alternately supply power from the same power source to LEDs of different colors. For example, all LEDs of the same color can be assigned a transistor that controls their power supply. In this case, all LED groups achieve the same color temperature. Alternatively, it is possible to operate the LEDs differently in groups. For example, consider the lighting of a very long hallway, where it is desired to illuminate certain areas near room doors with higher brightness, while requiring lower brightness further away from these areas. This type of 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 accessible at this address.This allows for dynamic responses to local needs such as higher brightness or a different light color.

[0053] It is considered advantageous, but not absolutely necessary, if 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 thereat.

[0054] For example, a single motion sensor or, if necessary, a series of motion sensors can be used to locally increase the brightness for a hotel guest walking down a particularly long, generally dimly lit corridor. Likewise, a contact sensor would make it possible to brighten up those areas of a larger cupboard arrangement with interior lighting where a user has just opened a door. Even with such a dynamic increase in brightness, the color temperature can be easily maintained, so that the dynamic increase in brightness is perceived as particularly pleasant and natural. If necessary, the brightness can be reduced slightly in other areas where a lot of power is already being drawn. This can easily be done by changing the on / off duty cycle. For example, it is particularly easy to do this during a period of less than 1 / 30 of a second., i.e. a period that can no longer be resolved by the eye, are cycled very often through all power channels, for example more than 10, 20 or 50 times each 1 / 30 sec. It should be mentioned that edge control is particularly advantageous with such rapid changes.

[0055] Subdued or dimmed lighting can then be achieved by, in addition to running through power channel cycles with channel excitation, also providing excitation pauses during which none of the power channels are excited. If such excitation pauses are sufficiently evenly distributed, no flickering is noticeable. An increase in lighting intensity can then be achieved in a simple manner by reducing the number of (preferably evenly distributed and thus short) excitation pauses at those points where the lighting intensity is to be increased. The excitation pauses can be divided, e.g., to allow a pause to elapse after each LED color is excited until the next LED color is excited, or alternatively, a single pause can be inserted after the LED excitation phases of all colors have been completed.Even with a single pause after the LED excitation phases of all colors have been completed, flickering is not observable if the cycles through the phases and pauses are sufficiently fast, i.e., the individual phases and pauses are sufficiently short. It should be noted that in embodiments in which not a single pause is inserted after the LED excitation phases of all colors have been completed, but rather a plurality of pauses are inserted, the pause durations do not necessarily have to be the same. For example, after the excitation of blue, there is no need to insert a pause that is exactly as long as the pause inserted after the excitation of green.It should be noted that pauses of equal length simplify the control structurally, but that pauses of different lengths can be advantageous because they allow the control of a specific point in the space of the HSV diagram (Hue-Saturation-Value, ie . The calculation of the chromaticity (e.g., hue, saturation, and brightness) is partly simplified. For example, in RGB / +W arrangements, the duty cycle can be derived from the HSV diagram, and for multiple individual colors, the duty cycle can vary according to the set intensity.

[0056] It is preferable if the LED DC power supply is designed to drive several groups of LEDs of all colors separately. This allows for a continuous supply even if simultaneous excitation of all LEDs would significantly exceed the total current or power due to the very low total impedance. By cycling sufficiently quickly through all groups, the impression of flicker-free lighting can be maintained for a long time.

[0057] It should be noted that when measuring the resistance of connected LEDs, the overload protection circuit usually only needs to record the real part of the resistance, but that a complete impedance measurement including an imaginary part is also possible.

[0058] Protection is also claimed for a method for controlling LEDs, wherein power from the same overload-protected LED power supply is supplied to a plurality of LEDs of different colors via a plurality of power channels, and the power channels are controlled in such a way that a color temperature results according to a power channel excitation ratio, if, for overload protection, a total current supplied to the LEDs, a total power supplied to the LEDs and / or a resistance of connected LEDs is detected, and in response to a total resistance that is too low, a current that is too high and / or a total power that is too high, the power channels are controlled in such a way that power is supplied to the LEDs of different colors so quickly and alternately while maintaining a color-determining excitation ratio that the alternation is not visually perceptible.

[0059] Various advantageous embodiments of this method are possible. It is considered particularly advantageous in such a method if the permissible extreme value is only slightly exceeded by the measured total current supplied to the LEDs, the total power supplied to the LEDs, and / or the total resistance of the connected LEDs, the power is supplied to color channels partially simultaneously and partially alternately, at least for some color temperatures.

[0060] Exceeding the extreme value of the resistance of all connected LEDs is seen in the fact that the total of the LEDs under consideration, including the associated switching arrangements, has an impedance that is too low; the impedance becomes lower when it is necessary to excite many LEDs because the LEDs are usually connected in parallel, for example by being arranged in parallel on LED strips.

[0061] Typically, the extreme value is chosen so that continuous operation of the arrangement is possible without the risk of component overload, overheating, etc. An exceedance is considered to be only slight if, despite the extreme value being exceeded when all LEDs or LEDs of all colors are supplied simultaneously, at least LEDs of two colors can still be supplied simultaneously without component overload or overheating being expected for the respective brightness or color temperature set. Furthermore, it can be advantageous if, during alternating operation of power channels, the switch-off of the power in a previously excited power channel is detected and, in response to a switch-off edge in the previously excited power channel, another channel is switched to power supply, preferably after a short overall off period and / or by dividing a overall off time.

[0062] It may also be advantageous if the plurality of LEDs of different colors are grouped into several groups and at least one group is controlled in such a way that a color temperature is obtained which is different from the color temperature of at least one other group.

[0063] In addition, it can be advantageous if the signals of at least one sensor are detected and, in response to the sensor signals received therefrom, a light intensity or a light temperature is changed, preferably changed locally.

[0064] The invention is explained below by way of example only and without limitation of generality, with reference to the drawing. It is represented by: Figure 1 shows an LED DC voltage supply of the present invention; Figure 2 shows the current flow through LEDs of different colors, which have a resistance intended for supply from the DC voltage supply, namely a- with white light and maximum excitation; b- with white light and dimmed excitation; c- with red-colored light and maximum excitation; d- with red-colored, dimmed light; Figure 3 shows the current flow through LEDs of different colors when the total resistance of the (parallel) connected LEDs is lower than intended for supply from the DC voltage supply, namely a- with white light and maximum excitation; b- with white light and dimmed excitation with several short, but identically long pauses; c- with white light and at the same brightness as in Fig. 3b dimmed excitement, but with a single longer pause instead of several shorter, but identically long pauses.

[0065] After Figur 1 an LED DC voltage supply 1, generally designated 1, has a plurality of power channels 2R, 2G, 2B, which are designed to supply power from the same power source 6 to LEDs 3R, 3G, 3B of different colors; the LED DC voltage supply 1 further comprises a microcontroller 4, which is designed to control the power channels 2R, 2G, 2B such that a color temperature results according to a power channel excitation ratio, as will be described with reference to the Figuren 2 and 3will be explained. An overload protection circuit 5 is also provided. The overload protection circuit 5 is designed to detect a total current supplied to the LEDs 3R, 3G, 3B, a total power supplied to the LEDs and / or a resistance of connected LEDs. The microcontroller 4 is designed, in response to an excessively low total resistance, an excessively high current and / or an excessively high total power, which are detected by the overload protection circuit and signaled to the microcontroller 4, to control the power channels 2R, 2G, 2B such that power is alternately supplied to the LEDs 3R, 3G, 3B of different colors while maintaining a color-determining excitation ratio, wherein the alternating between the power channels is so fast that the alternating is not visually perceptible.

[0066] The LED DC power supply has a positive supply terminal and a negative supply terminal. The supply line from the positive terminal to the LEDs includes a 5A shunt resistor and a power-switching transistor 5E, which terminates the current flow in the event of an overload. The current for all colored LEDs receiving power from power source 6 thus flows through this shunt resistor. The LEDs are wired so that the anodes of all LEDs are connected in parallel to the same line behind the power-switching transistor 5E.

[0067] In the present embodiment, which is particularly simple for reasons of ease of understanding, the LEDs 3R, 3G, 3B of different colors comprise red, green, and blue LEDs. In order to control these red, green, and blue LEDs so that a color temperature results according to a specific power channel excitation ratio, the microcontroller 3 has control outputs 4R, 4G, 4B, which are routed via corresponding lines 8R, 8G, 8B - and optionally via respective driver circuits (not shown) - to respective power-switching transistors 7R, 7G, 7B. These power-switching transistors 7R, 7G, 7B are each arranged in series with the LEDs assigned to them, i.e. the power-switching transistor 7R is in series with the red LED 3R; the power-switching transistor 7G is in series with the green LED 3G; and the power-switching transistor 7B is in series with the blue LED 3B.The currents flowing through the LEDs, possibly switched on by the power transistors, are collected on the line connected to the negative pole.

[0068] In the illustrated embodiment, a separate power switching transistor 7R, 7G, 7B is shown for each LED.

[0069] In practice, however, it is preferred that the power for several red LEDs 3R is switched via one and the same power-switching transistor 7R; the power for several green LEDs 3G can be switched via one and the same power-switching transistor 7G and the power for several blue LEDs 3B can be switched via 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 voltage supply 1, i.e.in the same housing, and a first dedicated line is then provided that leads to the cathodes of all red LEDs, a second dedicated line that leads to the cathodes of all green LEDs, and a third dedicated line that leads to the cathodes of all blue LEDs. Within the DC voltage supply 1, these three dedicated lines are then connected to their respective power-switching transistors, which in turn are all directly connected to a line leading to the pole, here the negative pole, of the DC voltage source 6.

[0070] The light-emitting surfaces of the red, green, and blue LEDs in a group are arranged so close together that they cannot be visually separated; when the three LEDs are excited simultaneously, the impression is created of a uniform luminous surface, whereby the color with which the surface glows is determined by the intensities with which each individual LED glows.

[0071] The DC voltage source 6 is designed to supply current to a specific number of LEDs simultaneously. If the number of connected LEDs exceeds the design limit of the DC voltage source 6, the DC voltage source 6 will be overloaded if an attempt is made to supply current to this excessive number of LEDs simultaneously.

[0072] The DC power supply connections are designed so that any number of LEDs can be electrically connected to the DC power 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 terminal blocks or identical socket / plug combinations are used to connect the LED strips. If a carrier strip that is too long is then connected to the DC power supply, too many red LEDs will require electrical power in parallel, as will too many green LEDs and too many blue LEDs.While it is possible, if necessary, to supply LED carrier strips up to three times the originally intended length by alternately supplying power to LEDs of only one color at a time, without drawing excessively large currents for which the DC voltage source 6 is no longer designed, this is no longer possible if all LEDs of different colors are to be supplied with power simultaneously.

[0073] The maximum load monitor 5 is designed to counteract overloading. The maximum load monitor initially comprises a 5A shunt resistor in the supply line leading from the positive pole of the DC voltage source to the anodes of the LEDs. The voltage drop across the 5A shunt resistor is fed to a comparator 5B, where it is compared with a maximum permissible voltage drop. This allows the analog current to be recorded in a simple manner without prior digitization, essentially performing an analog measurement. The comparator 5B outputs a first binary level, for example, 5V, if the voltage drop across the 5A shunt resistor is not greater than the maximum permissible voltage drop, whereas the comparator 5B outputs a second level, for example, 0V, if the voltage drop across the shunt resistor has exceeded the maximum permissible voltage drop.The comparator 5B has a holding element to maintain the second signal level even after a brief exceedance of the maximum permissible voltage drop across the shunt resistor until a reset signal is received from the microcontroller 4 via a line 5D.

[0074] The output of comparator 5B is first fed to a driver circuit 5C, which switches a power transistor 5E on as long as the comparator is at the first level and, in the illustrated embodiment, the microcontroller additionally signals via a corresponding digital signal on a further line 5G that power can in principle be output to the LEDs (for example, after initialization has been completed). In contrast, the power transistor 5E is switched off as soon as the comparator outputs the second level or the microcontroller does not output an enable signal on line 5G. The switching process by comparator 5B, which switches from the first level to the second level, indicating a critical condition, takes place so quickly that no damage due to overload occurs in any of the circuit elements until the power transistor is switched off.It should also be mentioned that the arrangement can be designed in such a way that the second line is optional, ie . an additional signal line from the microcontroller to the driver circuit is not necessary.

[0075] The output of comparator 5B is also fed to an input of microcontroller 4, so that the microcontroller receives information about whether a permissible maximum load is currently being exceeded. The microcontroller is assigned a memory in which a control program for the microcontroller is stored, the execution of which leads to the inventive operation of the arrangement.

[0076] 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 clarity, the LED strip should carry a permissible number of LEDs that can still be simultaneously supplied with power from the DC voltage source and are not defective.

[0077] An initialization cycle is then performed, during which the comparator first receives a reset signal via line 5D, causing driver circuit 5C to turn on power transistor 5E. A first short power pulse is then applied to the red LEDs, and only to these, by turning on power transistor 7R via line 2R from microcontroller 4.

[0078] It is then checked in the microcontroller 4 whether the comparator 5B has detected an excessively large voltage drop across the shunt resistor 5 A. Since this is not the case under the described conditions (defect-free, sufficiently short LED strip), it is determined that no error is present and subsequently a second short power pulse is fed to the green LEDs by switching the power transistor 7 G on via line 2 G from the microcontroller 4.

[0079] Again, it checks whether an excessive voltage drop was detected, and again it is determined that this was not the case. A third test cycle is performed with the blue LEDs, again without detecting any fault.

[0080] This means that the LED strip is short enough for the colors to be powered individually.

[0081] It is then checked whether two LED colors can be supplied with power simultaneously without an overload occurring.

[0082] For this purpose, all possible combinations of two LEDs are tested in pairs, one after the other: red and green LEDs; red and blue LEDs; and blue and green LEDs. The test is performed by simultaneously turning on the corresponding power transistors while applying a short test pulse. It is checked, as before, whether an overcurrent occurs. It should be noted that such a test of two LED combinations is useful because certain LEDs of a particular color may draw particularly high currents, and therefore the corresponding LEDs of a particular color cannot be excited simultaneously with LEDs of a different color. Under the conditions assumed here, the simultaneous excitation of two colors is uncritical.

[0083] Finally, a short power pulse is applied simultaneously to all three colors and again checked to see whether this leads to a maximum load being exceeded. Again, no overload is detected under the conditions assumed here.

[0084] The described initialization cycle requires only a short time. The excitation pulses applied for testing purposes are so short that even in the event of a failure, the most sensitive components in the circuit are not destroyed. At the same time, the excitation pulses are long enough that in the event of a failure, or if 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. It should be noted in this regard that if an overload condition is already detected for a color in single excitation mode, no further checks are performed to determine whether an overload condition also occurs when paired excitation is applied while this color is switched on. Rather, it is obvious that a color that already experiences an overload condition in 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, no check for overload-free simultaneous excitability of all three colors needs to be carried out.

[0085] It should also be noted that, if necessary, lower voltages could be applied to the individual color LEDs or to the combinations of compartment LEDs for the test case, but that this requires the provision of different voltage levels from the DC voltage source, which is generally undesirable due to the additional circuitry required.

[0086] After completing the test cycle, the connected LED DC power supply is ready to supply power to the LEDs. A white illumination with maximum intensity is initially activated via a remote control and a suitable interface of a remote control signal receiver to microcontroller 4 (both not shown).

[0087] White illumination is achieved when all LEDs are excited with equal power; maximum intensity is achieved when all LEDs receive a continuous excitation signal. Accordingly, the microcontroller sends a signal to all three lines 8R, 8G, 8B, causing the power transistors 7R, 7G, 7B assigned to the colors red, green, and blue to turn on, allowing current to flow through all three LEDs. As previously explained, no overload occurs with this simultaneous excitation of all LEDs. The voltage drop across the 5 A shunt resistor is so small that the voltage comparator 5B does not respond, and the power switching transistor 5E, assigned to all LEDs, can remain conductive in the connecting line between the positive pole and the LED anode.

[0088] When the user then gives the instruction via the remote control to dim the light, i.e., to reduce the intensity, this is achieved by no longer continuously supplying power to the LEDs. This is achieved by the LEDs only operating in pulses, as in Figur 2 B shown.

[0089] If the user subsequently commands a high intensity reddish illumination, as in Figur 2 C As shown, the red LED is continuously excited, while the blue and green LEDs are pulsed. Power can be supplied to all LEDs simultaneously. The exact desired shade of red can be adjusted by exciting the green and blue LEDs for different lengths of time. A slightly higher blue light intensity can be achieved by making the excitation phases for the blue LEDs longer than those for the green LEDs. Conversely, more green light can be added by making the excitation phases for the green LEDs longer than those for the blue LEDs.

[0090] The intensity of the red coloration can be adjusted by changing the pause times of green and blue LEDs; shortening the pause times results in a less intense coloration.

[0091] If the user wishes to reduce the brightness while maintaining the same color temperature and color intensity, the ratio of on / off times can be reduced in the same way for all LED colors. This is particularly useful if the user desires a low intensity, consistently reddish color. Figur 2-D It should be noted that all three LEDs are still energized simultaneously at certain times. This is not mandatory, but is particularly easy to implement in terms of circuitry.

[0092] Now assume that the user extends the existing LED strip during operation, i.e., without immediately running through another initialization cycle, by connecting another section, to a length of 2.5 times the original length. It is assumed that at 2.5 times the length, LED colors can still be excited individually, but that it should no longer be possible to excite LEDs of one color simultaneously with LEDs of any other color.

[0093] Immediately after connecting the longer section, the overload protection detects, based on the previous excitation pattern with simultaneous excitation of all colors, that the voltage drop across the shunt resistor is greater than permissible, meaning that the current flow is too high to allow continuous safe operation. Accordingly, the comparator signal switches from the first to the second level, which de-conducts the power transistor 5E and simultaneously signals to the microcontroller 4 that an overload has occurred.

[0094] Microcontroller 4 will then stop generating excitation pulses for power transistors 7R, 7G, and 7B, then reset comparator 5B and, in a test cycle similar to the system initialization after power-up, first check whether all LED colors can still be excited individually. To do this, a short, test excitation pulse is first output to excite only the red LEDs for transistor 7R; comparator 5B will not respond, since, despite the excessive length resulting from the use of the additional LED strip, no overload occurs with single-line excitation. The same results are obtained using short excitation pulses to excite only the green LEDs and then only the blue LEDs.

[0095] This confirms that operation is still possible per se. A check will then be made to see whether two colors can still be operated simultaneously. Given the length of the total connected LED strips chosen in the example, which significantly exceeds the limits, this is no longer the case.This is determined by the fact that, first, when a test pulse simultaneously exciting red and green LEDs is applied to the associated power transistors 7R and 7G, an overload situation occurs and is signaled to the microcontroller 4 via line 5D, whereupon the microcontroller resets the comparator; that, further, when the excitation pulses for the simultaneous excitation of the red and blue LEDs are provided, an overload situation also occurs, which in turn is signaled to the microcontroller 4 via line 5D and triggers a reset of the comparator; and that, finally, when power is applied simultaneously to green and blue LEDs for testing, an overload also occurs and is signaled to the microcontroller, whereupon the microcontroller again resets the comparator 5B.

[0096] It was thus determined on microcontroller 4 that the extended LED strip array can only be operated if each color channel is excited individually. It should be noted that this requires the LEDs of different primary colors to be operated in pulsed mode to achieve a given color, and thus the individual LEDs in the overall array will, on average, shine less brightly than in cases where continuous LED excitation is possible thanks to correct adaptation of the LED strip to the available power supply.

[0097] Now assume that the user initially wants to achieve the maximum possible brightness for white. This obviously requires energizing the LEDs of all colors one after the other.

[0098] Therefore, the microprocessor first provides a short pulse, which turns on the power transistor 7R. After this pulse, the LED 3G is energized for the same amount of time, and after the energization of the LED 3G is energized, the blue LED 3B is energized.

[0099] It is obvious that, on the one hand, pauses between excitation phases should be particularly short to ensure optimal utilization of the available power. It is also obvious that a situation should be avoided in which more than one LED color is inadvertently excited.

[0100] In principle, this can be achieved in various ways. For example, the microcontroller could repeatedly generate individual excitation pulses and directly control the corresponding power transistors 7R, 7G, and 7B. However, since this requires a comparatively high control effort, the individual colors can only be cycled slowly—without requiring additional effort from microcontroller 4. This is disadvantageous because this might make the color change more noticeable.

[0101] It would also be possible to increase a base clock by frequency multiplication and then determine the on / off phases by counting the frequency-multiplied clock signals. To permanently avoid spikes, however, this requires that the individual colors do not drift apart and, moreover, that LEDs of a first color are only switched on when the LEDs of the previously excited color are switched off.

[0102] The present invention achieves color sequence synchronization without great effort, such that LEDs of a color to be subsequently excited are only switched on after the LEDs of the previously excited color have been switched off. Structurally, this can be implemented without problems and with extremely little effort by waiting to switch on the excitation power for LEDs of a subsequent color until a falling edge is detected in the excitation power or excitation current for the LEDs of the previously excited color. Such detection is possible with simple logic gates.

[0103] It is also possible to store a pulse count value for each color channel, which specifies how many (possibly frequency-multiplied) clock pulses an LED of a given color is excited for until the excitation is terminated. Such a pulse count value only needs to be stored once in a register or similar for each LED color, as long as the retrieved lighting desired by the user does not change, i.e. neither the color temperature, intensity nor color tone is changed; after this, the microcontroller is no longer required to cycle through the LED sequence. Instead, the next color can be activated upon detection of the falling edge of the previous excitation pulse, i.e. the LEDs of the next color are supplied with power, and at the same time a counter is started from 0, which counts up clock pulses until the count value matches the count value stored for the currently excited color.In order to activate the respective LED, a corresponding signal can be sent to the power transistors 7 or the driver circuit provided for them, similar to how the transistor 5E controlling the total power receives a signal from the comparator 5B allowing or preventing the current conduction.

[0104] The falling edge can then be detected for the next LED to be excited and the process can be repeated for the next LED color to be excited.

[0105] From the foregoing, it is clear that with such a procedure, the color sequence can be cycled through repeatedly without intervention by the microcontroller 4 and that a color tone and a color temperature can also be selected.

[0106] In the arrangement just described, it is not yet possible in a simple way to insert the pause times required to reduce the maximum possible light intensity, during which no LEDs are energized at all. However, this can be easily changed by additionally providing a register in which the duration of an excitation pause to be provided between two successive excitations to reduce the intensity is stored. Then, upon detection of a falling edge, an excitation pause can first be provided by counting clock pulses without energizing any LED until the count value corresponds to the value stored in the respective register, and only then does the excitation of the subsequent LED begin. It is even sufficient to provide a single pause register if, as in Figur 3b shown, always equal pauses between each two excitation pulses <p1> = <p2> = <p3>should be inserted or if only a single break of the total length <p1> + <p2> + <p3>is inserted after all color groups have been passed through, as shown in Fig. 3c It should be noted that an implementation as shown in Fig. 3c As shown, it is particularly simple in terms of hardware, and with sufficiently fast cycling through all colors, no flickering or the like is to be expected, even if a single pause follows the excitation of all colors. It should also be mentioned that if the total off duration is divided into several pauses, these pauses may not all have the same length. For example, differences in the spectral sensitivity of the human eye and different efficiencies of LED light emission can be accounted for from the outset, for example, by using different illumination durations for each LED color to achieve a pure white maximum intensity.By reducing only the light intensity without changing the desired color, an on / off duty cycle can be calculated. This is obtained for all LED colors by multiplying with the same factor, but given the different lighting times from LED color to LED color, this leads to different lighting pauses for the different colors with pure white light.

[0107] Cycling between the individual colors can then be done very quickly without much effort, especially without much effort regarding the microcontroller after the setting has been made.

[0108] It should be mentioned that the described procedure also enables a very fast, dynamic change in the intensity and / or color of the light generated by an overall LED array or of the light generated by different groups in groups; in the preferred embodiments with edge detection, it is particularly advantageous that, until a change in the operating parameters, the microcontroller is essentially only required to feed on / off count values ​​into corresponding (local) registers, and no bandwidth-intensive control signals are required.

[0109] Dynamic light change thus preferably only requires a change to the locally stored register values, which also takes place quickly. In particular, there is no need to interrupt the lighting if the stored register values ​​can remain valid until they are changed thanks to edge detection, whereby, in particular, a successive change of the count values ​​stored in the individual registers can occur. This possibility of rapid changes makes the invention particularly suitable for responding dynamically to changing requirements—especially when areas to be illuminated more brightly, for example, have been previously defined.

[0110] It should also be noted that, if necessary—instead of explicitly testing for overload in groups as described—the impedance or a characteristic value of the connected LEDs can be determined by color and / or group. This can then be used, for example, to calculate which LEDs (groups) can be operated simultaneously. It is clear that channel groups for alternating operation can be preselected more precisely, especially with a known load, and power can be distributed accordingly. This can then, for example, better ensure that changes in intensity and / or color are only permitted to the extent that an overload does not occur.

[0111] To allow for precise measurement and thus an accurate calculation of the permissible settings of intensity and color saturation, 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 performing a simple analog measurement using a comparator. Fig. 1 For this option, a data line 5h is shown, which can be used to transmit the corresponding digitized current values ​​to the microcontroller. It should be noted, however, that this is not mandatory, but optional.

[0112] Furthermore, the impedance can also be determined using one or more low measurement voltages applied to the LEDs or groups of LEDs under test, by determining whether a certain current is exceeded in each case. If the currents flowing through the shunt resistor are detected by a comparator or the comparator when the measurement voltage is applied, or if it is detected whether a certain threshold is not exceeded when the measurement voltage is applied, the measurement voltage only needs to be provided at very low power; this is therefore simple in terms of circuitry.

[0113] Since it is possible to centrally record a total current, such a test for excessive currents can be carried out with little effort, because when all LEDs are tested sequentially or certain LED groups are tested sequentially, the necessary circuit is only needed once. < / p2> < / p1> < / p2> < / p1>

Claims

1. DC LED voltage supply (1) having a plurality of power channels (2R, 2G, 2B), which are configured to feed power from the same power source (6) to LEDs (3R, 3G, 3B) of different colours; a microcontroller (4), which is configured to drive power channels (2R, 2G, 2B) in such a way that a colour temperature is obtained in accordance with a power channel excitation ratio; and an overload protection circuit (5), wherein the overload protection circuit (5) is designed to detect an overall current fed to the LEDs (3R, 3G, 3B), an overall power fed to the LEDs (3R, 3G, 3B) and / or the resistance of LEDs connected; the DC LED power supply is designed to output a maximum power by simultaneous power output to LEDs of all colours when matched correctly; and the microcontroller (4) is designed, in response to too low a total resistance, too high a current and / or too high a total power, to drive the power channels (2R, 2G, 2B) in such a way that power is fed to the LEDs (3R, 3G, 3B) of different colours, while maintaining a colour-determining excitation ratio, in alternation, wherein the alternation between the power channels (2R, 2G, 2B) is so fast that the alternation is not visually perceptible.

2. DC LED voltage supply (1) according to the preceding claim, characterized in that the microcontroller is configured to drive power channels (2R, 2G, 2B) in such a way that, in the event of a permissible total current, they feed power from the same power source (6) to LEDs (3R, 3G, 3B) of different colours at least partially simultaneously.

3. DC LED voltage supply (1) according to the preceding claim, characterized in that power is conducted from the DC voltage power source (6) into the power channels (2R, 2G, 2B) via a two-pole connection, wherein the overload protection circuit (5) is designed to determine an instantaneous total power in the first line and the microcontroller (4) is configured to control connection of the power to the LEDs (3R, 3G, 3B) of different colours in current paths leading to the second line.

4. DC LED voltage supply (1) according to the preceding claim, characterized in that a turn-off circuit, which acts jointly on all power channels (2R, 2G, 2B), is provided in the first line, and a comparator of the overload protection circuit (5) is configured to drive said turn-off circuit directly.

5. DC LED voltage supply (1) according to any one of the preceding claims, characterized in that the microcontroller (4) is configured to change the duration of a switch-on operation.

6. DC LED voltage supply (1) according to any one of the preceding claims, characterized in that a controller is provided, which controller turns on a power channel, detects the switching off of the power in a previously excited power channel and switches another channel in a power-supplying manner in response to a switch-off edge in a previously excited power channel, preferably after a short total off period and / or with allocation of a total off time.

7. DC LED voltage supply (1) according to any one of the preceding claims, characterized in that the microcontroller (4) is designed to drive multiple groups of LEDs (3R, 3G, 3B) of all colours differently.

8. DC LED voltage supply (1) according to the preceding claim, characterized in that the microcontroller (4) has at least one additional sensor input and is configured to change, preferably locally change, a light intensity or a light temperature in response to sensor signals received at said input.

9. DC LED voltage supply (1) according to any one of the preceding claims, characterized in that the microcontroller (4) is configured, depending on a currently predefined desired colour temperature and depending on the magnitude of the deviation between the detected overall current fed to the LEDs (3R, 3G, 3B), the overall power fed to the LEDs (3R, 3G, 3B) and / or the overall resistance of connected LEDs (3R, 3G, 3B) and the respectively permissible extreme value, to drive power channels (2R, 2G, 2B) in such a way that power is fed to colour channels in partially simultaneously and partially alternately in the event of only a small permissible exceedance .

10. DC LED voltage supply (1) according to any one of the preceding claims, characterized in that the power output is pulse-width-modulated.

11. Method for driving LEDs (3R, 3G, 3B), wherein power from the same overload-protected DC LED voltage supply (1) is fed to a plurality of LEDs (3R, 3G, 3B) of different colours via a multiplicity of power channels (2R, 2G, 2B), and in this process the power channels (2R, 2G, 2B) are driven in such a way that a colour temperature in accordance with a power channel excitation ratio is obtained; wherein a maximum power is output by simultaneous power output to LEDs of all colours when matched correctly; and wherein, for the purpose of overload protection, an overall current fed to the LEDs (3R, 3G, 3B), an overall power fed to the LEDs (3R, 3G, 3B) and / or a resistance of LEDs (3R, 3G, 3B) connected is detected and the power channels (2R, 2G, 2B) are driven, in response to too low a total resistance, too high a current and / or too high a total power, in such a way that power is fed to the LEDs (3R, 3G, 3B) of different colours, while maintaining a colour-determining excitation ratio, in alternation and so fast that the alternation is not visually perceptible.

12. Method according to the preceding claim, characterized in that, in the event that the permissible extreme value is exceeded only slightly by the detected overall current fed to the LEDs (3R, 3G, 3B), the overall power fed to the LEDs (3R, 3G, 3B) and / or the overall resistance of connected LEDs (3R, 3G, 3B), power is fed to colour channels at least for some colour temperatures partially simultaneously and partially in alternation13. Method according to either one of the two the preceding claims, characterized in that, in alternating operation of power channels (2R, 2G, 2B), the switching off of the power in a previously excited power channel is detected and another channel is switched in a power-supplying manner in response to a switch-off edge in the previously excited power channel, preferably after a short total off period and / or with allocation of a total off time.

14. Method according to any one of Claims 11, 12 or 13, characterized in that the plurality of LEDs (3R, 3G, 3B) of different colours are grouped to form multiple groups and at least one group is driven in such a way that a colour temperature that is different from the colour temperature of at least one other group is obtained.

15. Method according to any one of Claims 11 to 14, characterized in that the signals of at least one sensor are detected and a light intensity or a light temperature is changed, preferably locally changed, in response to sensor signals received from said sensor.