DROOP CHARACTERISTICS OPTIMIZATION IN CONTEXT WITH PARALLEL-CONNECTED LED DRIVERS

Abstract

An LED driver (103) is provided for supplying a DC voltage at its output terminals to power an LED-based load (104). This LED driver (103) exhibits a droop characteristic (105) where the droop characteristic (105) decreases non-linearly.

Description

AREA OF INVENTION

[0001] In general, the invention relates to droop characteristic optimization in the context of parallel-connected LED drivers. Specifically, the invention relates to an LED driver for providing a DC voltage at its output terminals to supply an LED-based load, a measuring device for determining a droop characteristic of a system with several parallel-connected LED drivers for supplying an LED-based load, an LED driver with such a measuring device, a further LED driver for providing a DC voltage at its output terminals to supply an LED-based load, a measuring method for determining a droop characteristic of a system with several parallel-connected LED drivers for supplying an LED-based load, and a failure detection device for detecting the failure of at least one LED driver of a system with several parallel-connected LED drivers and an LED-based load.which is supplied by the parallel-connected LED drivers using a common output voltage of the parallel-connected LED drivers, and a method for failure detection of at least one LED driver of a system with several parallel-connected LED drivers and an LED-based load which is supplied by the parallel-connected LED drivers using a common output voltage of the parallel-connected LED drivers. BACKGROUND

[0002] To adequately supply a high-power LED-based load, for example, several constant voltage drivers or LED drivers can be connected in parallel. To enable such a parallel connection, the internal resistance of the corresponding voltage source must be simulated. In other words, the output voltage must decrease with a correspondingly higher current. This behavior, or the simulation of an internal resistance, is also known as a droop function.

[0003] Unfortunately, such droop functionality typically does not achieve optimal load balance and is also implemented using complex and expensive integrated circuits and / or microcontrollers, leading to corresponding inefficiencies. TASK AND SOLUTION

[0004] Accordingly, the object of the invention is to provide an LED driver for supplying a DC voltage at its output terminals for supplying an LED-based load, a measuring device for determining a droop characteristic of a system with several parallel-connected LED drivers for supplying an LED-based load, an LED driver with such a measuring device, a further LED driver for supplying a DC voltage at its output terminals for supplying an LED-based load, a measuring method for determining a droop characteristic of a system with several parallel-connected LED drivers for supplying an LED-based load, and a failure detection device for detecting the failure of at least one LED driver of a system with several parallel-connected LED drivers and an LED-based load, which is supplied by the parallel-connected LED drivers using a common output voltage of the parallel-connected LED drivers.and to provide a method for the failure detection of at least one LED driver of a system with several parallel-connected LED drivers and an LED-based load, which is supplied by the parallel-connected LED drivers using a common output voltage of the parallel-connected LED drivers, wherein the respective droop characteristic is optimized in such a way as to overcome the aforementioned disadvantages or to create additional advantages.

[0005] The problem is solved with respect to the LED driver for providing a DC voltage at its output terminals for supplying an LED-based load by the features of the first independent claim. The problem is solved with respect to the measuring device for determining a droop characteristic of a system with several parallel-connected LED drivers for supplying an LED-based load by the features of the second independent claim. The problem is solved with respect to the LED driver with such a measuring device by the features of the third independent claim. The problem is solved with respect to the further LED driver for providing a DC voltage at its output terminals for supplying an LED-based load by the features of the fourth independent claim.The problem is solved with respect to the measurement method for determining a droop characteristic of a system with several parallel-connected LED drivers for supplying an LED-based load by the features of the fifth independent claim. The problem is solved with respect to the failure detection device for detecting the failure of at least one LED driver of a system with several parallel-connected LED drivers and an LED-based load, which is supplied by the parallel-connected LED drivers using a common output voltage, by the features of the sixth independent claim.The problem with regard to the method for detecting the failure of at least one LED driver in a system with several parallel-connected LED drivers and an LED-based load, which is supplied by the parallel-connected LED drivers using a common output voltage, is solved by the features of the seventh independent claim. The dependent claims contain advantageous embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0006] According to a first aspect of the invention, an LED driver is provided for supplying a DC voltage at its output terminals to power an LED-based load. This LED driver exhibits a droop characteristic, wherein the droop characteristic decreases non-linearly.

[0007] Advantageously, this allows for improved load balance across the relevant load range, which can apply analogously to the following embodiment.

[0008] According to one embodiment of the first aspect of the invention, the droop characteristic curve decreases steadily.

[0009] According to one embodiment of the first aspect of the invention, in an upper, in particular higher, current range of the droop characteristic curve the correspondingly decreasing gradient is greater than in a lower, in particular lower, current range of the droop characteristic curve.

[0010] Advantageously, not only can the corresponding load balance be further optimized, but the corresponding voltage drop can also be kept low across the entire load range.

[0011] According to one embodiment of the first aspect of the invention, the correspondingly decreasing gradient differs by at least 20 percent, preferably 30 percent, particularly preferably 50 percent, most preferably 100 percent, in the upper current range compared to the lower current range.

[0012] Advantageously, this allows, for example, the best load balance to be achieved at maximum power.

[0013] According to one embodiment of the first aspect of the invention, the droop characteristic curve becomes continuously steeper. Alternatively, the droop characteristic curve has at least one jump in the correspondingly decreasing gradient, in particular such that the droop characteristic curve is composed of several differently steep, preferably linear, characteristic curve sections.

[0014] Advantageously, this can, for example, further improve the load balance across the entire load range.

[0015] According to a second aspect of the invention, a measuring device is provided for determining the droop characteristic of a system with several parallel-connected LED drivers for supplying an LED-based load. The measuring device is configured to act as a load for the system. Furthermore, the measuring device is configured to determine the droop characteristic using the load.

[0016] Advantageously, a previously unknown droop characteristic of a system can be determined, which allows the droop characteristic of an LED driver to be added to the system to be optimized accordingly, or to make the subsequent switching on of such an LED driver possible in the first place.

[0017] According to one embodiment of the second aspect of the invention, acting as a load is realized by means of appropriate mains feedback and / or by means of an ohmic resistance.

[0018] Advantageously, the energy extracted from the system can be efficiently and reliably dissipated.

[0019] According to one embodiment of the second aspect of the invention, the measuring device is configured to be connected in parallel to the parallel-connected LED drivers of the system. Additionally or alternatively, the measuring device is configured to disconnect the LED-based load from the corresponding supply by the system, particularly while the droop characteristic of the system is being determined.

[0020] Advantageously, the droop characteristic curve can thus be determined in a particularly precise way.

[0021] According to one embodiment of the second aspect of the invention, the measuring device has an interface for transmitting the correspondingly determined droop characteristic curve, in particular to at least one LED driver of the system and / or to at least one LED driver to be inserted into the system.

[0022] Advantageously, the droop characteristic of the LED driver in question can be optimized in a particularly efficient way.

[0023] According to a third aspect of the invention, an LED driver is created with a measuring device according to the second aspect of the invention or one of its embodiments.

[0024] Advantageously, the LED driver can automatically optimize its droop characteristic for the corresponding system.

[0025] According to a fourth aspect of the invention, an LED driver is provided for supplying a DC voltage at its output terminals to power an LED-based load. This LED driver has a droop characteristic and an interface by means of which the droop characteristic is programmable or at least modifiable.

[0026] Advantageously, the LED driver can be efficiently optimized with regard to its droop characteristic.

[0027] According to a fifth aspect of the invention, a measurement method is provided for determining the droop characteristic of a system with several parallel-connected LED drivers for supplying an LED-based load. This measurement method comprises the following steps: disconnecting the LED-based load from the corresponding supply by the system, if necessary; connecting a load element, in particular a dummy load element, which acts as a load for the system; and determining the droop characteristic using the load element.

[0028] Advantageously, a previously unknown droop characteristic of a system can be determined, which allows the droop characteristic of an LED driver to be added to the system to be optimized accordingly, or to make the subsequent switching on of such an LED driver possible in the first place.

[0029] According to a sixth aspect of the invention, a failure detection device is provided for detecting the failure of at least one LED driver of a system with several parallel-connected LED drivers and an LED-based load, which is supplied by the parallel-connected LED drivers using a common output voltage. The failure detection device is configured to detect a step in the common output voltage. Furthermore, the failure detection device is configured to use the detected step to detect a failure or at least a power loss of the at least one LED driver of the system.

[0030] Particularly in a cost-sensitive environment, it is advantageous that the parallel-connected LED drivers each have no interface or communication capability to the outside world in order to signal a corresponding failure.

[0031] According to one embodiment of the sixth aspect of the invention, the failure detection device is configured to output the detected failure or performance drop by means of a visual and / or acoustic signal.

[0032] Advantageously, a failure can be detected immediately in the corresponding control cabinet, for example, without the use of an additional measuring device.

[0033] According to one embodiment of the sixth aspect of the invention, the failure detection device has an interface by means of which the correspondingly detected failure or performance drop can be transmitted wirelessly and / or via a wired connection.

[0034] Advantageously, a failure can be detected remotely, for example.

[0035] According to an embodiment of the sixth aspect of the invention, the failure detection device is configured to detect and / or output, based on the corresponding extent of the jump in the common output voltage, which of the parallel-connected LED drivers of the system is the at least one LED driver for which the failure or power drop has been detected accordingly.

[0036] Advantageously, it is not necessary to check the functionality of the individual LED drivers.

[0037] According to a seventh aspect of the invention, a method for detecting the failure of at least one LED driver of a system with several parallel-connected LED drivers and an LED-based load, which is supplied by the parallel-connected LED drivers using a common output voltage, is provided. This method comprises the following steps: detecting a jump in the common output voltage, and detecting a failure or at least a power drop of the at least one LED driver of the system using the detected jump.

[0038] Particularly in a cost-sensitive environment, it is advantageous that the parallel-connected LED drivers each have no interface or communication capability to the outside world in order to signal a corresponding failure. DESCRIPTION OF PREFERRED FORMS

[0039] The following is a detailed exemplary description of some embodiments of the invention with reference to the figures in the drawing. This shows: Fig. 1 an exemplary output current-output voltage diagram with a characteristic curve without droop characteristic and with a characteristic curve with droop characteristic; Fig. 2 an exemplary equivalent circuit diagram of a typical battery; Fig. 3 an exemplary embodiment of an LED driver for providing a DC voltage at its output terminals for supplying an LED-based load and an exemplary nonlinear droop characteristic of the LED driver; Fig. 4 an exemplary output current-output voltage diagram with two linear droop characteristics and two operating points; Fig. 5 an exemplary output current-output voltage diagram with two nonlinear droop characteristics and two operating points; Fig. 6 an exemplary output current-output voltage diagram with a non-linear droop characteristic; Fig. 7 an exemplary output current-output voltage diagram with a non-linear droop characteristic; Fig. 8 an exemplary output current-output voltage diagram with a non-linear droop characteristic; Fig. 9 an exemplary output current-output voltage diagram with a non-linear droop characteristic; Fig. 10 an exemplary output current-output voltage diagram for the case of a dynamic adjustment of the respective parameters of the corresponding droop characteristic; Fig. 11 an exemplary embodiment of a measuring device for determining a droop characteristic curve; Fig. 12 an exemplary embodiment of a measuring device for determining a droop characteristic curve; Fig. 13 an exemplary embodiment of an LED driver with a measuring device for determining a droop characteristic curve; Fig. 14 an exemplary embodiment of an LED driver with a measuring device for determining a droop characteristic curve; Fig. 15 an exemplary embodiment of an LED driver with an interface by means of which a corresponding droop characteristic can be programmed or at least modified; Fig. 16 an exemplary flowchart of a measurement procedure for determining a droop characteristic of a system with several parallel-connected LED drivers for supplying an LED-based load; Fig. 17 an exemplary embodiment of a failure detection device for the failure detection of at least one LED driver of a system with several parallel-connected LED drivers and an LED-based load, which is supplied by the parallel-connected LED drivers by means of a common output voltage of the parallel-connected LED drivers, wherein the LED drivers each have the same maximum output power; Fig. 18 a further illustration of the embodiment according to Fig. 17. Output current-output voltage diagram; Fig. 19 one to Fig. 17 analog embodiment, wherein the LED drivers each have different maximum output powers; Fig. 20 a further illustration of the embodiment according to Fig. 19. Output current-output voltage diagram; and Fig. 21 An exemplary flowchart of a method for failure detection of at least one LED driver of a system with several parallel-connected LED drivers and an LED-based load which is supplied by the parallel-connected LED drivers using a common output voltage of the parallel-connected LED drivers.

[0040] In principle, LED drivers, which can be designed as constant voltage sources or at least be based on them, can be operated individually or in parallel. An efficient way to connect constant voltage sources in parallel is for the LED drivers to have a droop characteristic.

[0041] Fig. Figure 1 illustrates an exemplary output current-output voltage diagram with a characteristic curve 100 without droop characteristic and with a characteristic curve 101 with droop characteristic.

[0042] A constant voltage source, which literally delivers a constant voltage regardless of the magnitude of the corresponding output current, has a characteristic curve of 100. Such a voltage source is less suitable, or even unsuitable, for a parallel connection of several voltage sources.

[0043] To achieve good load balance, a droop characteristic according to curve 101 can be used. In this case, the corresponding constant voltage source or "quasi-constant voltage source" imitates the behavior of a battery with internal resistance. For the sake of completeness, it shows Fig. 2 the typical equivalent circuit of a battery with an internal resistance of 102. Accordingly, the droop characteristic leads to the intended reduction of the output voltage with the output current.

[0044] As part of the Fig. 1. This reduction occurs linearly according to characteristic curve 101. As the current increases, the output voltage drops from a maximum output voltage, for example 52 V, to a minimum output voltage, for example 48 V.

[0045] The steepness of the characteristic curve has a significant influence on the properties of the corresponding system consisting of parallel-connected constant voltage sources or LED drivers and an LED-based load.

[0046] Generally, a flat characteristic curve results in a low voltage drop across the load range, but also in relatively poor load balance. Conversely, a steep characteristic curve leads to good load balance, but also to a relatively high voltage drop across the load range.

[0047] Unfortunately, the corresponding advantages and disadvantages apply within the framework of a linear characteristic curve, such as characteristic curve 100 according to Fig. 1, always across the entire load range.

[0048] Fig. Figure 3 now illustrates an embodiment of an LED driver 103 for providing a DC voltage at its output terminals to supply an LED-based load 104. This LED driver 103 has a droop characteristic or droop curve, the corresponding droop curve being exemplified by the curve 105 in Figure 3. Fig. 3, decreases non-linearly.

[0049] This allows, for example, the aforementioned advantages and disadvantages to be optimized, especially with regard to load.

[0050] For the sake of completeness, the output current-output voltage diagram of the Fig. 3 also an exemplary characteristic curve 106 for the case that no droop characteristic is implemented, while the exemplary characteristic curve 107 illustrates the case of a linear droop characteristic.

[0051] Regarding the non-linear droop characteristic 105, it should also be noted that it can be particularly advantageous if the droop characteristic 105 decreases continuously.

[0052] Furthermore, it can be particularly advantageous if, in an upper, especially higher, current range of the droop characteristic curve 105, the correspondingly decreasing gradient is greater than in a lower, especially lower, current range of the droop characteristic curve 105.

[0053] Furthermore, it can be particularly advantageous if the correspondingly decreasing gradient differs by at least 20 percent, preferably 30 percent, particularly preferably 50 percent, and most preferably 100 percent in the upper current range compared to the lower current range.

[0054] Advantageously, the characteristic curve 105 achieves the best possible load balance at maximum output power. This prevents overloading or the need to oversize the corresponding LED driver. At low loads, however, balance is no longer the primary concern.

[0055] Furthermore, a relatively low voltage drop is advantageously achieved across the entire load range, even though the droop characteristic is based on inducing such a voltage drop. The characteristic curve 105 keeps the change across the load range as small as possible, since the consumers or the corresponding LED-based load 104 typically have upper and lower limits.

[0056] It should be noted that ideally, all characteristic curves of the parallel-connected LED drivers should overlap. In practice, however, differences typically arise, leading to an uneven load balance. The following figures illustrate this: Fig. 4 and the Fig. 5. The behavior with a relatively large offset error.

[0057] While the Fig. Figure 4 shows an exemplary output current-output voltage diagram with two linear droop characteristics and two operating points, illustrating Fig. 5 An exemplary output current-output voltage diagram with two nonlinear droop characteristics and two operating points.

[0058] In the case of the Fig. 4. The corresponding load balance is identical everywhere or across the entire load range, which is particularly disadvantageous in the area of ​​maximum power, as the load balance is relatively poor there.

[0059] In contrast, the Fig. 5 clearly shows that the respective non-linear characteristic curve, which is flat in the area of ​​a lower output current and steep in the area of ​​a higher output current, not only results in a comparatively lower voltage drop across the load range, but also in an improved load balance at maximum power.

[0060] Furthermore, the Fig. 6, Fig. 7, Fig. 8, Fig. 9. Each of these shows another exemplary output current-output voltage diagram with a non-linear droop characteristic. The explanations of these droop characteristics 108, 109, 110, 111 can each be applied analogously to the characteristic 105 described above, and vice versa.

[0061] In general, with regard to a nonlinear droop characteristic, it can be particularly advantageous if the droop characteristic becomes continuously steeper. Additionally or alternatively, it can be particularly advantageous if the droop characteristic is strictly monotonically decreasing.

[0062] Furthermore, it can be particularly advantageous if the droop characteristic curve has at least one jump in the correspondingly decreasing gradient, in particular such that the droop characteristic curve is composed of several differently steep, preferably linear, characteristic curve sections.

[0063] This case is exemplified by characteristic curve 108 according to Fig. Figure 6 illustrates the nonlinear droop characteristic curve 108, which exhibits two jumps in the correspondingly decreasing gradient, so that the droop characteristic curve is composed of three differently steep, internally linear, characteristic curve sections.

[0064] In light of the nonlinear droop characteristic curve 109 according to Fig. 7. Furthermore, it can be particularly advantageous if the nonlinear droop characteristic curve consists of or includes at least two straight lines and at least one inflection point. For example, characteristic curve 109 consists of two straight lines and one inflection point WP1. Preferably, the curve switches between the corresponding straight lines at the at least one inflection point or at inflection point WP1.

[0065] Further examples illustrate Fig. 8 a nonlinear droop characteristic 110, which consists of three straight lines and two inflection points WP1, WP2. Preferably, the inflection points can also serve as corresponding switching points.

[0066] In light of the nonlinear droop characteristic curve 111 according to Fig. 9. It can be particularly advantageous if the nonlinear Droop characteristic curve consists of, or includes, at least one straight line, one exponential function (especially a rotated exponential function), and one inflection point. For example, the Droop characteristic curve 111 consists of a straight line, one inflection point WP1, and one exponential function (rotated in the representation). Here, too, the inflection point WP1 can function as a corresponding switching point.

[0067] The mathematical functions underlying the nonlinear droop characteristics or their inflection points can be predefined, for example, at the factory.

[0068] It can be particularly advantageous to adapt or modify the functions in the field. This can be done, for example, on the LED driver itself or via a suitable building management system.

[0069] In light of the Fig. 10, which shows an exemplary output current-output voltage diagram for the case of a dynamic adjustment of the respective parameters of the corresponding droop characteristic or droop curve, it should be noted that it can be particularly advantageous if the mathematical functions underlying the non-linear droop curve or its inflection points are adjusted, preferably automatically, by the LED driver itself during operation.

[0070] It can be particularly advantageous if the LED driver detects when it has reached steady state. This can occur, for example, when the output current and voltage no longer change. In this case, the slope of the droop characteristic can be increased. This prevents the operating point from changing, and the current distribution remains unchanged.

[0071] When the load changes and defined thresholds are exceeded – as exemplified in Fig. If the 10 marked values ​​are exceeded, the corresponding LED driver can advantageously switch back to the flat or flatter characteristic curve or to the flat or flatter characteristic curve section until the LED driver is back in steady state.

[0072] Now to Fig. Figure 11 shows an exemplary embodiment of a measuring device 200 for determining a droop characteristic of a system with several parallel-connected LED drivers, for example with two parallel-connected LED drivers 201, 202, for supplying an LED-based load 203, for example LED strips and / or spots. The measuring device is configured to act as a load for the system. Furthermore, the measuring device is configured to determine the droop characteristic using the load.

[0073] In this context, it should be noted that a significant advantage of parallel-connected LED drivers is the ability to increase system performance by subsequently adding additional LED drivers. Existing systems can be flexibly expanded and adapted.

[0074] To ensure that the interaction of the LED drivers works smoothly, it is advantageous if the corresponding droop characteristic or droop curve is first determined by the measuring device 200.

[0075] The relevant parameters of the droop characteristic of the existing system, or the mathematical functions underlying the droop characteristic or droop curve, can then be parameterized in the newly connected LED driver, especially before it begins operation. This advantageously allows for error-free operation and optimized, or even ideal, load balancing.

[0076] Another advantage is that the droop characteristic or droop curve of an existing system does not necessarily have to be known (e.g., if it is an older system). Furthermore, the droop characteristic or droop curve can change over time (e.g., due to aging).

[0077] Thus, the measuring device 200 makes it possible to ascertain a potentially unknown droop characteristic or droop curve, which enables the subsequent switching on of LED drivers in existing systems or installations in a particularly efficient manner.

[0078] According to Fig. 11 The measuring device 200 or the droop characterizer is connected in parallel to the outputs of the existing LED drivers 201, 202.

[0079] The measuring device 200 is configured to function as a variable load. Furthermore, the measuring device 200 can be configured to measure, preferably continuously, the load current and the output voltage of the existing LED drivers 201, 202.

[0080] It can be particularly advantageous if the measuring device 200 is configured to determine the droop characteristic or droop curve in the output window by varying the load current. During the measurement or determination of the droop characteristic or droop curve, the regular load or the LED-based load 203 is switched off, preferably by the measuring device 200 or by measurement personnel, in particular to avoid distorting the corresponding measurement results.

[0081] It should be noted that the energy drawn from the system by measuring device 200 must be directed somewhere. In this context, Fig. 11. Furthermore, it can be seen that this energy is fed back into the power grid 204 via grid feedback. This grid feedback can be implemented, for example, using a boost topology.

[0082] Therefore, it can be particularly advantageous if the above-described effect as a load is realized using appropriate grid feedback.

[0083] It can also be particularly advantageous if the above-described action as a load is realized using an ohmic resistor. This is exemplified by... Fig. 12 illustrated:

[0084] In another embodiment 210 of the measuring device, energy is converted into heat in a heating resistor 205. In this embodiment, the measuring device 210, or the droop characterizer, does not require a mains connection. The resistor 205 can be located either internally within the measuring device 210 or externally.

[0085] Furthermore, it can be particularly advantageous if, especially in order to determine the droop characteristic of the system, the measuring device 200 or the measuring device 210 is configured to approach at least two measuring points, preferably at least three measuring points, particularly preferably at least four measuring points, and most preferably four or five measuring points.

[0086] Since these points only need to be accessed very briefly (for the duration required to complete the corresponding current / voltage measurement), even a high power consumption of resistor 205 or grid feedback should not be a problem. Advantageously, neither grid feedback nor resistor 205 needs to be designed for continuous operation at high power levels.

[0087] Once the characterization is complete, the measuring device 200 or 210, or the droop characterizer, can be disconnected from the system. The newly added LED driver can then be parameterized with the measured droop characteristic or droop curve and connected to the system.

[0088] Furthermore, it shows Fig. 13 An exemplary embodiment of an LED driver 220 with a measuring device for determining a droop characteristic of a system with several LED drivers connected in parallel. This measuring device of the LED driver 220 is based, by way of example, on the measuring device 200 according to Fig. 11.

[0089] Accordingly, the LED driver 220 itself has the capability to measure or determine the droop characteristic or droop curve. For this purpose, the LED driver 220 preferably assumes a different role within the system. It can be particularly advantageous if the LED driver 220 is configured to function not as a voltage or current source, but as a load, during the measurement or determination of the droop characteristic or droop curve.

[0090] Preferably, the LED driver draws a defined load current from the system or lighting system and measures the output voltage. The other LED drivers in the corresponding parallel circuit, for example LED drivers 201 and 202, are preferably operating normally.

[0091] Advantageously, this allows the relevant load range to be covered and the droop characteristic or droop curve to be recorded or determined.

[0092] It can be particularly advantageous if the LED driver 220 is configured to automatically apply the corresponding parameters or mathematical functions for its own droop characteristic or droop curve after the measurement or determination of the droop characteristic has been completed. Preferably, normal operation of the system with all drivers (new and old) then begins.

[0093] Furthermore, it should be noted that here too, the regular load or the LED-based load 203 is preferably switched off for the duration of the characterization, in particular to avoid distorting the measurement.

[0094] Furthermore, it shows Fig. 14 An exemplary embodiment of an LED driver 230 with a measuring device for determining a droop characteristic of a system with several LED drivers connected in parallel. This measuring device of the LED driver 230 is based, by way of example, on the measuring device 210 according to Fig. 12.

[0095] In analogy to the measuring device 210, energy is converted into heat in a heating resistor 206. The resistor 206 can be located either internally within the LED driver 230 or externally. If the resistor 206 is external, it is sufficient for it to be connected only during the droop characterization; the resistor 206 is not required for normal operation.

[0096] It can still be particularly advantageous if the LED driver is 220V according to Fig. 13 or the LED driver 230 according to Fig. 14 is configured to automatically determine the droop characteristic or droop curve at regular intervals. This can occur, for example, at times when the corresponding LED-based load 203 or the corresponding lighting is already switched off, such as at night. Preferably, this automatic determination results in a corresponding adjustment of the droop characteristic or droop curve of the LED driver in question. Furthermore, it should be noted that it can be particularly advantageous if the measuring device 200 or 210 orThe LED driver 220 or 230 has an interface for transmitting the correspondingly determined droop characteristic, in particular to at least one LED driver of the system and / or to at least one LED driver to be inserted into the system, for example to the LED driver 201 and / or the LED driver 202 and / or an LED driver that replaces the LED driver 201 and / or 202, and / or an LED driver that is to be newly added to the system.

[0097] In this context in particular, it can be especially advantageous to provide an LED driver for supplying a DC voltage at its output terminals for supplying an LED-based load, which has a droop characteristic and an interface by which the droop characteristic can be programmed or at least modified.

[0098] Fig. Figure 15 illustrates an exemplary embodiment of such an LED driver 240 with such an interface 207.

[0099] Fig. Figure 16 shows an exemplary flowchart of a measurement procedure for determining a droop characteristic of a system with several parallel-connected LED drivers for supplying an LED-based load.

[0100] A first step 251 involves disconnecting the LED-based load from the corresponding supply by the system, if necessary.

[0101] A second step 252 involves switching on a load element, in particular a dummy load element, which acts as a load for the system.

[0102] A third step, 253, involves determining the droop characteristic using the load element. Preferably, both voltage and current measurements are performed as part of this determination of the droop characteristic.

[0103] Now, let us explicitly point out the fundamental advantage that can be achieved by connecting multiple LED drivers in parallel. By connecting several LED drivers in parallel, the corresponding power can be intentionally oversized, resulting in a redundant, fail-safe system. If one LED driver fails, the remaining LED drivers will then preferentially take over the load.

[0104] Especially in cost-sensitive environments, the parallel-connected LED drivers lack any interface or communication capability to the outside world. If one LED driver fails, for example in the corresponding control cabinet, this typically goes unnoticed because the remaining LED drivers take over the load. This particularly jeopardizes the system's reliability, as in the worst-case scenario, a defective driver is neither replaced nor repaired.

[0105] Therefore, a failure detection device is required for detecting the failure of at least one LED driver in a system with multiple parallel-connected LED drivers and an LED-based load, which is supplied by the parallel-connected LED drivers using a common output voltage. The failure detection device is configured to detect a step in the common output voltage. Furthermore, the failure detection device is configured to use the detected step to detect a failure or at least a power loss of the at least one LED driver in the system.

[0106] Fig. Figure 17 illustrates an exemplary embodiment of such a failure detection device 300 for the failure detection of at least one LED driver of a system with several parallel-connected LED drivers 301, 302, 303 and an LED-based load 304, which is supplied by the parallel-connected LED drivers 301, 302, 303 by means of a common output voltage of the parallel-connected LED drivers 301, 302, 303.

[0107] Preferably, the failure detection device 300 is located, in particular in the corresponding control cabinet, between the source or the parallel-connected LED drivers 301, 302, 303 and the LED-based load 304.

[0108] It can be particularly advantageous if the failure detection device 300 is configured to measure or determine the voltage across the LED-based load 304 as well as the current through the LED-based load 304. Advantageously, the power of the LED-based load 304 is known at all times.

[0109] Furthermore, it can be particularly advantageous if the failure detection device 300 is configured to determine or calculate the expected voltage that must result at the corresponding power and / or the respective droop characteristic or droop curve of the parallel-connected LED drivers 301, 302, 303. Preferably, the failure detection device 300 is configured to compare the calculated voltage with the measured voltage. If these values ​​match, the parallel-connected LED drivers 301, 302, 303 can be assumed to be functioning correctly. Otherwise, it can be assumed that at least one of the LED drivers 301, 302, 303 is not functioning correctly or has failed.

[0110] Furthermore, it can be particularly advantageous if the failure detection device 300 is configured in such a way that the corresponding total system power and / or the maximum output voltage of the LED drivers 301, 302, 303 and / or the minimum output voltage of the LED drivers 301, 302, 303 can be transmitted to it and / or stored in it.

[0111] Additionally or alternatively, it can be particularly advantageous if the failure detection device 300 is configured in such a way that the droop characteristic curve(s) of the LED drivers 301, 302, 303 can be transferred to it and / or stored in it.

[0112] Furthermore, Fig. 17. It is observed that each of the LED drivers 301, 302, and 303 has, for example, the same maximum power of 48 W. The LED-based load 304 has, for example, a maximum power of 50 W.

[0113] Furthermore, each of the LED drivers 301, 302, 303 exhibits, for example, a linear droop characteristic curve, such as that shown by the Fig. 1 shows (see characteristic curve 101).

[0114] Therefore, the following applies to the output voltage V out or also for the output voltage of the first LED driver 301 and the output current I1 of the first LED driver 301, the following equation: Vout=k1∗I1+d1

[0115] Similarly, the following applies to the second LED driver 302: Vout=k2∗I2+d2

[0116] Similarly, the following also applies to the third LED driver 303: Vout=k3∗I3+d3

[0117] Therefore, the following equation results for the corresponding output power: P=Vout(I1+I2+I3)

[0118] Equations (1) to (4) result in a linear system of equations, where all k n , all d nand P are known. By solving this system of equations, all I can be determined. n as well as V out Calculate the expected output voltage, which can then be compared to the actually measured output voltage.

[0119] One of the further illustrations of the embodiment according to Fig. 17. Output current-output voltage diagram according to Fig. Figure 18 clearly shows that the three LED drivers 301, 302, and 303 each have the same power output and / or characteristics. The linear droop characteristic 308 of the first LED driver 301, the linear droop characteristic 309 of the second LED driver 302, and the linear droop characteristic 310 of the third LED driver 303 are congruent.

[0120] If all three LED drivers 301, 302, 303 are operating correctly, a first operating point 311 is achieved. In this case, the corresponding output voltage is 50.7 V.

[0121] If, for example, one of the three LED drivers 301, 302, 303 fails, a second operating point 312 results. In this case, the corresponding output voltage is 50 V. This difference is advantageously detected by the failure detection device 300.

[0122] Fig. Figure 19 shows another exemplary embodiment, which is based on the Fig. 17 is based on the LED-based load 304, which is again 50 W as an example. However, the three LED drivers 305, 306, and 307 each have different maximum power ratings. For example, the first LED driver, 305, has a maximum power rating of 48 W, the second LED driver, 306, has a maximum power rating of 24 W, and the third LED driver, 307, has a maximum power rating of 10 W.

[0123] One of the further illustrations of the embodiment according to Fig. 19. Output current-output voltage diagram according to Fig. 20 makes it clear that the corresponding slope (k n ) the respective droop characteristic or droop curve of the LED drivers 305, 306, 307 changes, especially since the LED drivers 305, 306, 307 have different output power.

[0124] The Fig. From 20, it can be seen that the first LED driver 305 has, by way of example, the linear droop characteristic 313, the second LED driver 306 has, by way of example, the linear droop characteristic 314, and the third LED driver 307 has, by way of example, the linear droop characteristic 315.

[0125] If all three LED drivers 305, 306, 307 are operating correctly, a first operating point 316 is achieved. In this case, the corresponding output voltage is 49.6 V.

[0126] If, for example, the second LED driver 306 fails, a second operating point 317 results. In this case, the corresponding output voltage is 48.6 V.

[0127] With regard to the failure detection device 300, it should be noted that it may be particularly advantageous if the failure detection device 300 is configured to output the detected failure or performance drop by means of a visual and / or acoustic signal.

[0128] Furthermore, it can be particularly advantageous if the failure detection device 300 has an interface by means of which the correspondingly detected failure or performance drop can be transmitted wirelessly and / or via wired connections.

[0129] For example, the interface for connecting the failure detection device 300 to a cloud or cloud storage can be configured, particularly to transmit relevant system diagnostic data. This system diagnostic data could, for example, relate to the maximum system performance and / or the detected failure or performance drop of an LED driver.

[0130] Furthermore, it can be particularly advantageous if the failure detection device 300 is configured to use the detected jump to determine whether one of the LED drivers needs to be recalibrated. Preferably, the failure detection device 300 is configured to determine which of the LED drivers needs to be recalibrated.

[0131] Furthermore, it can be particularly advantageous if the failure detection device 300 is configured to determine or calculate the system performance of the correspondingly connected LED drivers, in particular on the basis of the maximum and / or minimum output voltage of the LED drivers.

[0132] Furthermore, it can be particularly advantageous if the failure detection device 300 is configured to determine the corresponding maximum system power, especially on the basis of the maximum and / or minimum output voltage of the LED drivers, preferably during a corresponding new installation.

[0133] Finally, it illustrates Fig. 21 An exemplary flowchart of a method for failure detection of at least one LED driver of a system with several parallel-connected LED drivers and an LED-based load which is supplied by the parallel-connected LED drivers using a common output voltage of the parallel-connected LED drivers.

[0134] A first step 321 involves detecting a jump in the common output voltage. A second step 322 involves detecting a failure or at least a power drop of the at least one LED driver of the system using the detected jump.

[0135] The invention is not limited to the embodiments discussed above. All features described in the description, claimed in the claims, or shown in the drawing can be combined with one another in any way within the scope of this invention.

Claims

[1] LED driver (103) for providing a DC voltage at its output terminals for supplying an LED-based load (104), comprising: a droop characteristic curve (105, 108, 109, 110, 111), where the droop characteristic curve (105, 108, 109, 110, 111) decreases non-linearly. [2] The LED driver (103) according to claim 1, wherein the droop characteristic (105, 108, 109, 110, 111) decreases continuously. [3] The LED driver (103) according to claim 1 or 2, wherein in an upper, in particular higher, current range of the droop characteristic (105, 108, 109, 110, 111) the correspondingly decreasing gradient is greater than in a lower, in particular lower, current range of the droop characteristic (105, 108, 109, 110, 111). [4] The LED driver (103) according to claim 3, wherein the correspondingly decreasing gradient differs by at least 20 percent, preferably 30 percent, particularly preferably 50 percent, most preferably 100 percent, in the upper current range compared to the lower current range. [5] The LED driver (103) according to claim 3 or 4, wherein the droop characteristic curve (105, 108, 109, 110, 111) becomes continuously steeper, or wherein the droop characteristic curve (108, 109, 110, 111) has at least one jump in the correspondingly decreasing gradient, in particular such that the droop characteristic curve is composed of several differently steep, preferably linear, characteristic curve sections. [6] Measuring device (200, 210) for determining a droop characteristic of a system with several parallel-connected LED drivers (201, 202) for supplying an LED-based load (203), wherein the measuring device (200, 210) is configured to act as a load for the system, and wherein the measuring device (200, 210) is set up to determine the droop characteristic using the load. [7] The measuring device (200, 210) according to claim 6, wherein the action as a load is realized by means of appropriate mains feedback and / or by means of an ohmic resistor (205). [8] The measuring device (200, 210) according to claim 6 or 7, wherein the measuring device (200, 210) is configured to be connected in parallel to the parallel-connected LED drivers (201, 202) of the system, and / or wherein the measuring device (200, 210) is configured to disconnect the LED-based load (203) from the corresponding supply by the system, in particular while the droop characteristic of the system is determined. [9] The measuring device (200, 210) according to one of claims 6 to 8, wherein the measuring device has an interface for transmitting the correspondingly determined droop characteristic curve, in particular to at least one LED driver (201, 202) of the system and / or to at least one LED driver to be inserted into the system. [10] LED driver (220, 230) with a measuring device (200, 210) according to one of claims 6 to 9. [11] LED driver (240) for providing a DC voltage at its output terminals for supplying an LED-based load, comprising: a droop characteristic curve, and an interface (207) by means of which the droop characteristic can be programmed or at least modified. [12] Measurement method for determining a droop characteristic of a system with several parallel-connected LED drivers for supplying an LED-based load, comprising the following steps: Disconnect (251) the LED-based load from the corresponding supply by the system, if necessary, Switching on (252) a load element, in particular a dummy load element, which acts as a load for the system, and Determine (253) the droop characteristic using the load element. [13] Failure detection device (300) for failure detection of at least one LED driver of a system with several parallel-connected LED drivers (301, 302, 303, 305, 306, 307) and an LED-based load (304) which is supplied by the parallel-connected LED drivers (301, 302, 303, 305, 306, 307) by means of a common output voltage of the parallel-connected LED drivers (301, 302, 303, 305, 306, 307), wherein the failure detection device (300) is configured to detect a step in the common output voltage, and wherein the failure detection device (300) is configured to detect a failure or at least a power drop of the at least one LED driver of the system by means of the correspondingly detected step. [14] The failure detection device (300) according to claim 13, wherein the failure detection device (300) is configured to output the correspondingly detected failure or performance drop by means of a visual and / or acoustic signal. [15] The failure detection device (300) according to claim 13 or 14, wherein the failure detection device (300) has an interface by means of which the correspondingly detected failure or performance drop can be transmitted wirelessly and / or via a wired connection. [16] The failure detection device (300) according to one of claims 13 to 15, wherein the failure detection device (300) is configured to detect and / or output, based on the corresponding extent of the jump in the common output voltage, which of the parallel-connected LED drivers (301, 302, 303, 305, 306, 307) of the system is the at least one LED driver for which the failure or power drop has been detected accordingly. [17] Method for detecting the failure of at least one LED driver of a system with several LED drivers connected in parallel and an LED-based load which is supplied by the parallel LED drivers using a common output voltage of the parallel LED drivers, comprising the following steps: Detecting (321) a jump in the common output voltage, and Detecting (322) a failure or at least a drop in performance of the at least one LED driver of the system by means of the appropriately detected jump.

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