AT525308A2 - POWER SUPPLY ARRANGEMENT AND LIGHTING SYSTEM - Google Patents

Abstract

A power supply arrangement for operating parallel-connected LED lighting units comprises a constant-current LED driver which is designed to supply the LED lighting units with a direct voltage current; a voltage measuring device, which is designed to continuously measure an output voltage of the constant current LED driver; and a control device which is designed to monitor a change in the measured output voltage and to reduce an output power of the constant current LED driver if a change in the output voltage of more than a predefined tolerance limit is detected.

Description

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POWER SUPPLY ARRANGEMENT AND LIGHTING SYSTEM

TECHNICAL FIELD OF THE INVENTION

The invention relates to a power supply arrangement for operating parallel-connected LED lighting units and a lighting system with such a power supply arrangement.

TECHNICAL BACKGROUND

If several LED lighting units are to be operated with one operating device, they are usually connected in series to the operating device. One reason for this is that in a parallel connection, the failure of one of the luminaires (open circuit) could result in an output current from the control gear being distributed to the remaining luminaires, which means that they are each exposed to a larger current. In the case of series-connected LED lights, on the other hand, an output voltage of the control gear must be increased accordingly for each additional light unit. For example, an output voltage of the control gear of 105 V is required for three serial lights with an operating voltage of 35 V per light. Such high output voltages at an operating device are undesirable and/or disadvantageous for some applications.

Constant voltage LED drivers are known from the prior art (English: "Constant Voltage LED Driver"), which are designed for the operation of lighting systems in which several LED modules are connected in parallel. In this case, LED modules which connected to the constant voltage LED driver should be equipped with a current limiting device to avoid potential damage to the LED modules, such as a resistor, a constant current resistor or an active current control, such current limiters can provide precise output current sharing and smooth light output across the LED modules, however, such current limiters typically regulate the current by dissipating excess power, which is why

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Constant voltage LED drivers can have comparatively low efficiency.

SUMMARY OF THE INVENTION

One object of the invention is to find solutions for supplying power to LED lighting units which avoid high output voltages and are nevertheless efficient.

This and other objects are achieved by a power supply arrangement with the features of claim 1 and by a lighting system with the features of claim 14.

According to a first aspect of the invention, a power supply arrangement for operating parallel-connected LED lighting units comprises a constant-current LED driver which is designed to supply the LED lighting units with a DC voltage current; a voltage measuring device, which is designed to continuously measure an output voltage of the constant current LED driver; and

a control device which is designed to monitor a change in the measured output voltage and to reduce an output power of the constant current LED driver if a change in the output voltage of more than a predefined tolerance limit is detected.

According to a further aspect of the invention, a lighting system includes a power supply arrangement according to the invention.

One of the ideas on which the present invention is based is to implement a parallel connection of lighting units on a (DC) operating device based on a constant current LED driver, the output voltage of which is continuously monitored in order to reduce its output power to protect the LED lighting units suitable to reduce. This can, for example, prevent potential damage to individual or all lights if one or more of the lights fail. Furthermore, assuming that all lighting units require the same operating voltage, the DC voltage

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of the driver correspond to the operating voltage of the individual lights. Only the amperage of the output current can increase compared to a serial connection, which is unproblematic for many areas of application.

This is implemented using a protective arrangement with a constant current LED driver, a voltmeter, a control device (e.g. a microcontroller) and at least two LED lighting units (connected in parallel). The voltmeter can be constantly, i.e. continuously , transmit information to the microcontroller. Based on this, the microcontroller can evaluate the measured voltage. If the voltage deviates (e.g. due to the failure of one of the lights or due to another defect or error) to a defined extent from specified reference values and/or from one under normal conditions If the behavior deviates from the expected behavior, the microcontroller reduces the output power of the driver to protect the remaining lamps.For example, the microcontroller can instruct the driver to cut off the power supply to individual or all lamp units to prevent damage.

Advantageous refinements and developments result from the further dependent claims and from the description with reference to the figures.

According to one development, the control device can be designed to cause the constant current LED driver to dim the LED lighting units by adjusting the output power.

A complete shutdown of individual or all LED lighting units is thus avoided. Instead, the microcontroller can instruct the driver to choose an appropriate dimming state for the lighting units in which they are not damaged despite the failure of one or more of the lights. The LED light units are thus dimmed together, i.e. their output and thus also the current flow through the individual lights are reduced, but they continue to be operated. The corresponding reduced light emission can indicate to a user that there may be a malfunction or the failure of individual lights.

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According to one development, the LED lighting units can be dimmable by means of pulse width modulation or constant current reduction.

Thus, for example, the current flow through the lighting units can be reduced (English: "Constant Current Reduction", CCR). Alternatively, a pulse duration or pulse width modulation (English: "Pulse Width Modulation", PWM) or another suitable method can also be used in principle .

According to a development, the tolerance limit can be selected in such a way that the tolerance limit is exceeded if at least one of the LED lighting units fails,

The tolerance limit is therefore specially designed to be exceeded if individual LED lighting units fail, so that appropriate measures can be taken in this case.

According to one development, the control device can be designed to adjust the measured output voltage to a target voltage and to reduce the output power of the constant current LED driver if it is determined that the output voltage deviates from the target voltage by more than the predefined tolerance limit.

The setpoint voltage can be stored by the manufacturer in a memory of the device, for example. Alternatively or additionally, a setpoint voltage can also be determined once when the intact and error-free device is first put into operation and then stored in the memory. In this sense, it can also be provided that the setpoint voltage is determined again at a given time. For example, a calibration mode of the device can be provided for this purpose. In principle, the target voltage can also be determined in a more or less automated manner during operation.

Instead of such a comparison between an actual voltage and a target voltage, a voltage change (significant change) during operation could alternatively or additionally be determined. For example, the measured actual voltage could be compared to past voltage measurements, e.g., by evaluating a moving average/average or the like.

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According to one development, the control device can be designed to automatically determine the setpoint voltage during operation.

This means that the device can also determine the setpoint voltage in an automated manner during ongoing operation.

According to one development, the constant current LED driver, the voltage measuring device and/or the control device can be integrated in a common operating device.

In particular, these devices can be integrated together in a single operating device. Alternatively, however, separate units can also be provided for these devices.

According to one development, the power supply arrangement can include a non-volatile data memory for storing the tolerance limit and/or the target voltage.

In particular, this data memory can be integrated into the operating device, in which the constant current LED driver, the control device and the voltage measuring device are located. It is also possible for the data memory to be integrated directly into the control device.

According to one development, a large number of output voltages can be provided for different dimming levels of the LED lighting units with associated tolerance limits and/or target voltages.

For example, the lighting system can be a continuously or stepwise dimmable system. Since the measured output voltage differs depending on the currently set dimming level, the arrangement in this development is therefore able to take into account the expected setpoint output voltages for each of the possible dimming levels. In principle, a suitable tolerance limit can be assigned to each dimming level.

According to one development, the control device can be designed to cycle through the dimming levels one after the other and the respectively measured ones

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Store output voltages as target voltages in the non-volatile data memory.

The target voltages therefore do not have to be stored on the device by the manufacturer, but can only be “learned” after the fully functional system has been commissioned, in that the device runs through the individual dimming levels one after the other and saves the output voltage measured for each dimming level as the target voltage.

According to one development, the control device can be designed to run through discrete dimming levels and to interpolate the target voltage for comparison with the output voltage between the discrete dimming levels.

Practically, with stepless dimming, hardly every dimming level can be measured. Instead, however, it can be measured against specific, predefined levels. The associated voltages can be stored accordingly. Based on this, a target output voltage can then be determined for every conceivable dimming level using suitable calculation methods.

According to one development, the power supply arrangement can also include an actuating device which, when actuated by a user, is designed to cause the control device to run down the dimming level and to detect the respective target voltages.

For example, a push button can be provided on a surface of the arrangement for this purpose, by means of which a “self-learning mode” is started (to be carried out, for example, after the initial assembly or when a recalibration is to be carried out). All dimming levels can be passed through within a short period of time, e.g. approx. 30 seconds, and the target voltages for each level can be (permanently) saved.

According to one development, the tolerance limits can take temperature-related voltage changes of the constant current LED driver into account.

Since LED lighting units heat up during operation and the output voltage typically changes at higher temperatures, the

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Know the expected voltage changes due to temperature changes and take them into account in the tolerance limits. Differences within these limits defined in this way could then be accepted as natural temperature fluctuations. Larger differences, in turn, can indicate a lamp failure or another error or defect, so that the control device can then initiate appropriate measures.

The above configurations and developments can be combined with one another as desired, insofar as this makes sense. Further possible configurations, developments and implementations of the invention also include combinations of features of the invention described above or below with regard to the exemplary embodiments that are not explicitly mentioned. In particular, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the present invention.

SHORT CONTENT OF THE FIGURES

The present invention is explained in more detail below with reference to the exemplary embodiments given in the schematic figures. They show:

1 shows a schematic view of a lighting system with a power supply arrangement according to an embodiment of the invention; and

FIG. 2 shows a schematic detailed view of the power supply arrangement from FIG.

The accompanying figures are intended to provide a further understanding of embodiments of the invention. They illustrate embodiments and, together with the description, serve to explain principles and concepts of the invention. Other embodiments and many of the foregoing advantages will become apparent by reference to the drawings. The elements of the drawings are not necessarily shown to scale with respect to one another. Directional terminology such as "top", "bottom", "left", "right", "above", "below", "horizontal", "vertical", "front", "back" and similar indications are used for descriptive purposes only purposes and are not intended to limit the generality to specific configurations as shown in the figures.

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In the figures of the drawing, elements, features and components that are the same in function and have the same effect are provided with the same reference symbols unless otherwise stated.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Figure 1 shows a schematic view of a lighting system 10 with a power supply arrangement 1 according to an embodiment of the invention. Fig. 2 is a schematic detail view of the power supply arrangement of Fig. 1.

The lighting system 10 comprises a number of LED lighting units 2 connected in parallel to a contact current LED driver 3, e.g. individual LED modules such as COB modules or the like with a number of LEDs. Purely as an example, three such LED lighting units 2 are shown in FIG. It goes without saying that this is to be understood purely as an example and in other embodiments only two or alternatively more than three LED lighting units 2 can be provided.

The constant-current LED driver 3 is designed to supply the LED lighting units 2 with a DC current | to supply. Should one of the LED lighting units 2 fail, the associated partial currents 1-3 would increase accordingly via the remaining LED lighting units 2, which in extreme cases can lead to the LED lighting units 2 being damaged. In order to avoid this, several electronic elements are provided in a protective arrangement in the form of an integrated operating device 16, as will be explained in more detail with reference to FIG.

For the sake of clarity, only one of the LED lighting units 2 from FIG. 1 is shown in FIG. 2 as a representative load. This is supplied with a DC current by the constant current LED driver 3 . For this purpose, the constant current LED driver 3 is fed with an input AC voltage Ur, which is provided via a voltage supply 9, then converted into an output DC voltage U, e.g. 35 V, and via a protective device 14 (e.g. a short-circuit protection) and an EMC output filter 13 the LED lighting units 2 is passed on.

The output voltage is continuously measured via an interposed voltage measuring device 4, e.g. periodically

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time intervals. The operating device 16 also has a control device 5, e.g. a microprocessor or a microcontroller, which is designed to monitor a change in the measured output voltage U and, if a change in the output voltage U is detected by more than a predefined tolerance limit, an output power of the constant current LED driver 3 to reduce. The control device 5 can be connected to a network in a known manner via a control interface 11 and can use this to receive and transmit control signals, e.g. DALI signals.

The control device 5 is designed in particular to adjust the measured output voltage U to a target voltage and to reduce the output power of the constant current LED driver 3 if it is determined that the output voltage U deviates from the target voltage by more than the predefined tolerance limit. The tolerance limit can be selected in such a way that the tolerance limit is exceeded if at least one of the LED lighting units 2 fails. The tolerance limit or target voltage can be stored in a non-volatile data memory 6 of the operating device 16 . It goes without saying that other relevant parameters can also be measured. For example, the measurement of the output voltage can include the detection of a rate of change (time-dependent differential behavior).

In a specific embodiment, the control device 5 can be designed to cause the constant current LED driver 3 to dim the LED lighting units 2 by adjusting the output power. For example, the constant current through the LED lighting units 2 can be suitably reduced for this purpose. Of course, it goes without saying that other suitable dimming methods can also be used, e.g. PWM. In principle, the LED lighting units 2 can also be switched off completely.

The lighting system 10 of FIGS. 1 and 2 can be gradually or continuously dimmable. Because the measured output voltage U differs depending on the dimming level, in this case there is an associated target voltage for each dimming level. The arrangement 1 must therefore be able to know or learn the expected target voltages for each of the possible dimming levels. For this purpose, the operating device has an actuating device 7, e.g. a push button on a housing surface, by means of which a self-learning mode can be started (e.g. to be carried out after initial installation and/or during

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recalibration). All dimming levels are passed through within a few to a few seconds and the associated output voltages are stored in the data memory 5 as target voltages for each level.

In the case of a continuously dimmable lighting system 10, not every dimming level can of course be approached. For this reason, only a predetermined number of discrete dimming levels can be provided, which are then approached. In this case, the setpoint voltage for matching with the output voltage U can be interpolated by the control device 5 between the discrete dimming levels.

Since LEDs heat up during operation and the output voltage U also changes at higher temperatures, the control device 5 can know corresponding tolerance limits of expected voltage changes in comparison with the target values from the self-test (for each dimming level). Differences within these limits are explained by temperature variations. Larger differences mean a lamp failure and the control device 5 can cause the remaining lamp units 2 (by the driver 3) to be dimmed to a minimum level without delay.

It goes without saying that the setpoint voltages or tolerance limits can be determined and stored in the data memory 6 not only during start-up or commissioning or already by the manufacturer. Alternatively or additionally, it can also be provided that the setpoint voltages are also determined and/or defined during operation. This can, for example, be carried out automatically by the control device 5 in accordance with the self-learning mode (e.g. after each switching on of the lighting system 10 or at regular time intervals during operation).

It is also understood that the operating device 16 or the power supply arrangement 10 can have other common elements or functions. For example, as shown in FIG. 2 , one or more status LEDs can be provided on the operating device 16 . The self-learning process can thus be represented or displayed via such indication LEDs. The operating device 16 or the control device 5 can be operated via a selector switch 15, e.g. a DIP switch. For example, the (DC) current for supplying the LED lighting units 2 can be adjusted

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being. Target values and system information (number of lights, temperature fluctuations, voltages, tolerance limits) could also be transferrable via an interface (not shown).

Furthermore, it is not necessary for the output voltage U to be compared with a predetermined target voltage or with a plurality of target voltages. Alternatively or additionally, a significant change in voltage during operation can also be detected. For this purpose, the measurement of the output voltage can include, for example, the calculation of a sliding mean value, a weighted arithmetic mean value, etc. Expected changes in voltage can be taken into account and included by changing the dimming level.

It goes without saying that the present description can only go into the details relevant to the invention. When putting the arrangement 1 into practice, a person skilled in the art will take into account correspondingly known elements. For example, the measurement of the output voltage can contain an integration element, a voltage divider, a low-pass filter for smoothing the voltage value, etc. The output voltage can be measured galvanically isolated via optocouplers, via an operational amplifier circuit, etc. The output voltage can also be measured indirectly via a current measurement, with the current being proportional to the output voltage, or as a differential voltage measurement, etc.

In the foregoing Detailed Description, various features have been grouped together in one or more examples to improve the rigor of presentation. However, it should be understood that the above description is merely illustrative and in no way restrictive. It is intended to cover all alternatives, modifications, and equivalents of the various features and embodiments. Many other examples will be immediately and immediately apparent to those skilled in the art in view of the above description.

The exemplary embodiments were selected and described in order to be able to present the principles on which the invention is based and its possible applications in practice in the best possible way. This enables those skilled in the art to optimally modify and use the invention and its various exemplary embodiments in relation to the intended application. In the claims

as well as the description, the terms “including” and “having” are used as neutral terms for the corresponding terms “comprising”. Furthermore, use of the terms "a", "an" and "an" is not intended to cover a plurality of such described features and components

generally ruled out.

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- 13 LIST OF REFERENCE NUMBERS

Power supply arrangement LED lighting unit Constant current LED driver Voltage measuring device Control device Data memory Actuation device Control signals Voltage supply Lighting system Control interface Status LED EMC output filter Protection device Selector switch

Control gear DC current Partial currents Output voltage AC input voltage

Claims (1)

15 20 25 30 35 - 14 CLAIMS Power supply arrangement (1) for operating LED lighting units (2) connected in parallel, comprising: a constant-current LED driver (3) which is designed to supply the LED lighting units (2) with a DC voltage current (I); a voltage measuring device (4) which is designed to continuously measure an output voltage (U) of the constant current LED driver (3); and a control device (5) which is designed to monitor a change in the measured output voltage (U) and to reduce an output power of the constant current LED driver (3) if a change in the output voltage (U) of more than a predefined tolerance limit is detected . Power supply arrangement (1) according to claim 1, wherein the control device (5) is designed to cause the constant current LED driver (3) to dim the LED lighting units (2) by adjusting the output power. Power supply arrangement (1) according to Claim 2, in which the LED lighting units (2) can be dimmed by means of pulse width modulation or constant current reduction. Power supply arrangement (1) according to one of Claims 1 to 3, the tolerance limit being selected in such a way that the tolerance limit is exceeded if at least one of the LED lighting units (2) fails. Power supply arrangement (1) according to any one of claims 1 to 4, wherein the control device (5) is designed to adjust the measured output voltage (U) with a target voltage and when determining a deviation of the output voltage (U) from the target voltage of more than the predefined Tolerance limit to reduce the output power of the constant current LED driver (3). 15 20 25 30 35 10 11. 12. 13. - 15 - Power supply arrangement (1) according to claim 5, wherein the control device (5) is designed to automatically determine the setpoint voltage during operation. Power supply arrangement (1) according to any one of claims 1 to 6, wherein the constant current LED driver (3), the voltage measuring device (4) and / or the control device (5) are integrated in a common operating device (16). Power supply arrangement (1) according to one of Claims 1 to 7, also having a non-volatile data memory (6) for storing the tolerance limit and/or the target voltage. Power supply arrangement (1) according to one of Claims 1 to 8, a multiplicity of output voltages (U) being provided for different dimming levels of the LED lighting units (2) with associated tolerance limits and/or target voltages. Power supply arrangement (1) according to claim 9, wherein the control device (5) is designed to run the dimming levels clocked one after the other and to store the respectively measured output voltages (U) as setpoint voltages in the non-volatile data memory (6). Power supply arrangement (1) according to claim 10, wherein the control device (5) is designed to run through discrete dimming levels and to interpolate the target voltage for comparison with the output voltage (U) between the discrete dimming levels. Power supply arrangement (1) according to Claim 10 or 11, further having an actuating device (7) which, when actuated by a user, is designed to cause the control device (5) to run down the dimming level and to detect the respective target voltages. Power supply arrangement (1) according to any one of claims 1 to 12, wherein the tolerance limits take temperature-related voltage changes of the constant current LED driver (3) into account. 14. Lighting system (10) with a power supply arrangement (1) according to any one of claims 1 to 13.