DE102010034079A1 - Electrical control device for controlling power supply to LEDs of lighting device that is utilized for general lighting purposes, has switching converter comprising set of inductors that comprises common magnetic core - Google Patents

Abstract

The device (V) has a switching converter (4) comprising a set of inductors (L1-L3) that comprises a common magnetic core (K). A set of consumers i.e. LEDs (D, D11 to D1n, D2n to D21, D31 to D3n), is divided into strands (1-3), where each inductor is switched in series to each consumer in each strand. Windings of the inductors are applied in the common magnetic core with same winding sense, where the inductors exhibit same number of windings. The common magnetic core is designed as a closed magnetic core, and a switching device controls power supply to the consumers.

Description

The present invention relates to an electric control device, and more particularly to an electric control device for controlling lighting devices.

As technology advances in the manufacture of light-emitting diodes (LEDs) and the associated ever-increasing light output and lifetime, lighting devices using light-emitting diodes are increasingly used for general and special lighting purposes. For a greater light intensity or a lighting device for emitting a distributed light and greater light intensity, a plurality of light-emitting diodes are generally active simultaneously as a result of the limited light intensity of a single light-emitting diode, wherein preferably a plurality of light-emitting diodes can be provided and formed in corresponding geometric arrangements. In this case, the plurality of light-emitting diodes can be connected in different groups in parallel and in series.

In applications for lighting devices based on light emitting diodes, the individual LEDs with regard to their performance (light output) and their light color (color temperature) is selected. Various light colors as well as infrared radiation or ultraviolet radiation are possible, wherein generally the emitted light is within a limited spectral range.

In the case of light-emitting diodes, the light output is approximately proportional to the operating current (that is to say to the current consumption of the light-emitting diode in the forward direction), with an exponentially increasing current-voltage characteristic also dependent on the temperature. An operation of the light-emitting diodes by means of a constant current is preferred, with the operating voltage setting. As is customary in semiconductor components, light-emitting diodes have a corresponding specimen scattering, so that this must be taken into account in the wiring of the light-emitting diodes in different groups in series and in parallel.

In operation, a corresponding brightness adjustment or power control and regulation can be achieved by means of a corresponding pulse width modulation (PWM) of the operating variables.

For the connection of light-emitting diodes to a power source, which generally carry out an operation with a substantially constant current, a correspondingly dimensioned series resistor can be used, or the light-emitting diodes can be operated from a power supply unit with a transformer and a rectifier and a corresponding capacitor become. Likewise, operation with a correspondingly dimensioned electronic circuit in the form of a constant current source makes sense. These two cases, however, form lossy operating or control options.

Another possibility is the use of a switching regulator, which in operation correspondingly high frequencies are used, so that a flicker of the LEDs is barely perceptible to the human eye. Here, the switching regulator essentially has a constant current source behavior.

Due to the low light intensity of individual light-emitting diodes, as stated above, a multiplicity of light-emitting diodes are used which can alternately be connected in series in groups and several groups in each case in parallel.

4 shows schematically such an arrangement.

According to 4 is an electrical converter (for example, a switching converter) W connected to a mains voltage U1 with its primary side via a power switch S0 and outputs at its secondary side of a voltage U2 and an associated current for a plurality of LEDs D. The plurality of light-emitting diodes D is connected in series and in parallel in the above-mentioned manner, four strands or branches ST1 to ST4 being provided in the present example. The four strings ST1 to ST4 are connected in parallel with each other, wherein the voltage U2 is applied to each string.

Each of the strands ST1 to ST4 comprises an equal number of identical light-emitting diodes D, which are connected in series to one another within one of the strands or branches ST1 to ST4.

According to 4 For example, the first strand ST1 comprises the light-emitting diodes D11 to D1n connected in series, and in the same way the second strand ST2 comprises the light-emitting diodes D21 to D2n connected in series with one another. This applies equally to the third and fourth strand ST3 and ST4.

In a general form, each of the strands ST1 in each case comprises a switch S1 to S4 with which individual strands can also be switched on or off.

In operation of the plurality of light-emitting diodes according to 4 The converter W outputs the voltage U2 which can be varied to a certain extent, so that essentially a constant, controlled current is supplied to the LEDs in the series and parallel connection.

In the ideal case, ie assuming ideal and completely identical components, the same current flows in each of the strings ST1 to ST4. In an actual embodiment of the light-emitting diode according to 4 However, within the entire circuit, including all light-emitting diodes, differences occur due to their specimen scattering, so that a desired uniform current distribution is not guaranteed. Thus, the specimen scattering as well as, for example, different line lengths when connecting the individual strands in series connected light-emitting diodes as well as, for example, contact resistances in case of deteriorated contacts cause problems in the current distribution of parallel-connected strands.

In the series connection of the respective light emitting diodes, for example, the light emitting diodes D11 to D1n of the first strand ST1 according to 4 , the number of light-emitting diodes in dependence on the supply voltage U2 and the respective forward voltage of the individual LEDs is determined, so that the number of LEDs and thus the number of the respective forward voltages in their sum in the vicinity of the supply voltage ranges. The sum of the forward voltages or operating voltages of the light emitting diodes corresponds to the so-called burning voltage of the respective strand ST1 to ST4. Since the luminosity of a strand is not sufficient, the multiple strands are connected in parallel until the desired or required luminosity or light intensity is achieved as a result of the totality of the light-emitting diodes used then.

To avoid an overload or a too small load of the individual strands ST1 to ST4 of the light-emitting diodes, the currents in each branch should be equally (parity) divided. This can in the present example of an arrangement (circuit) according to 4 be carried out by appropriate series resistors R, as in 4 are shown for each strand, as well as for example by current mirror circuits, but both measures in their application lead to a corresponding power loss. With the arrangement according to 4 a uniform current distribution in the individual strands ST1 to ST4 can not be guaranteed, so that there is also the possibility that in each strand a separate switching converter is provided with the behavior of a constant current source.

However, this considerably increases the costs and makes it necessary to monitor and possibly control or regulate the switching converters for approximately the same lighting conditions in the individual strings (with their own switching converter). In this case, a uniform current distribution and thus a uniform light output of the individual strands can not be guaranteed.

The present invention is therefore based on the object to design an electrical control device such that in the control of a plurality of strands of LEDs with simple measures a uniform current distribution and thus a uniform light output are guaranteed.

According to the invention, this object is achieved by the electrical control device having the features of patent claim 1.

This object is likewise achieved according to the present invention by a lighting device having the features of patent claim 11.

The present invention thus relates to an electrical control device which is connectable to a plurality of consumers, for controlling the power supply to the consumers, wherein the plurality of consumers is divided into at least two strands each having the same number of consumers connected in series, with a switching converter with a number of inductances, wherein in each strand an inductance is connected in series with the respective consumers, and the inductances have a common magnetic core.

The electric control device according to the present invention, i. H. the corresponding circuit arrangement thus comprises, in conjunction with a switching converter, an arrangement of a plurality of inductors or coils, wherein each strand of a plurality of strings with light-emitting diodes connected in series with one another is assigned an inductance or coil (winding). The plurality of coils are arranged in such a way that they are arranged on a common magnetic core (for example, an iron core), so that via the associated magnetic field each coil is coupled to each further coil, notwithstanding that the coils are also connected via the circuit arrangement and the other components are galvanically connected to each other.

By means of the coupling or interlinking existing via the magnetic field, it is possible to achieve a corresponding compensation within the entire circuit arrangement. It compensation can be achieved to the effect that, for example, by example scattering or by temperature differences of individual LEDs in respective strands or whole strands occurring smaller or larger currents (and thus a smaller or larger light output of the respective light-emitting diodes) the currents are compensated, so approximately one uniform current distribution and thus also a substantially uniform light output of the individual light-emitting diodes or of the individual strands in series connected light-emitting diodes is achieved. This occurs especially when specimen scatters or temperature differences accumulate in the strands.

The uniformity of the current distribution within the plurality of strings involved in series connected light-emitting diodes can be achieved by the common magnetic core on which all participating inductors or coils (windings) are arranged and form part of the light emitting diode driving switching converter. The magnetization energy in the common magnetic core is divided approximately equally with the same design of the winding, so that this leads to approximately the same currents in the individual coils (windings) and thus in the respective strands with the light-emitting diodes connected in series. In this case, a capacitive component of the electrical properties of the LEDs can also be used.

As apart from the connected loads in the form of the plurality of light-emitting diodes no relevant ohmic components (such as series resistors) are in the connected strands of the electrical control device, the above solution in conjunction with the features of claim 1 of the efficiency and the resulting Cost clearly superior to previous technical solutions.

The present invention may also relate to a lighting device comprising: a plurality of light-emitting diodes serially connected to each other in at least two strands having an equal number in each strand, and the electric control device connectable to the plurality of light-emitting diodes and mentioned above. The design of the lighting device with the control device results from the achieved current balance between the strands or branches a uniform light output and a uniform power and thus light distribution within the lighting device, which can be compensated even during operation adverse effects of resulting temperature changes.

Further embodiments of the present invention are specified in the dependent claims.

Respective windings of the inductors can be applied to the common magnetic core in the same winding sense, and the windings of the inductors can have the same number of turns.

The windings of the inductors may be stacked or stacked on the common magnetic core. Here, the windings of Induktivtäten be formed multifilar.

In the apparatus, the common magnetic core may be a closed magnetic core.

The switching converter may have a switching device for controlling the power supply to the consumers. In this case, the switching device can have a control connection and the input signal at the control connection can be a PWM signal.

In the apparatus, a freewheeling element may be connected in parallel with the at least two strands. The consumers can be light-emitting diodes.

The present invention will be described in more detail below by means of embodiments with reference to the drawings. Show it:

1 a schematic representation of a circuit arrangement of the electrical control device which is connected to a plurality of strings of light emitting diodes,

2 a schematic representation of the arrangement of a plurality of coils (windings) on a common magnetic core,

3 a schematic representation of a circuit arrangement for operating a plurality of strings of series-connected LEDs, wherein the strands are divided into several groups, and

4 a circuit arrangement for operating a plurality of strings of series-connected LEDs according to the prior art.

The following will be described in detail with reference to 1 A first embodiment of the present invention is described.

1 shows a schematic and simplified representation of a circuit arrangement of The electric control device V according to the present invention (hereinafter simply referred to as a device) according to a first embodiment, which is connected to a plurality of loads, for example in the form of light-emitting diodes D. The plurality of arranged in at least two strings LED D is, for example, as shown in FIG 1 in three groups or three strands 1 . 2 and 3 divided up. The first strand 1 includes the light emitting diodes D11 to D1n and thus the number of n light emitting diodes. The second strand 2 includes the light emitting diodes D21 to D2n and thus the same number n of LEDs, and it also includes the same number n of the third strand 3 the LEDs D31 to D3n. It is assumed here that the light-emitting diodes D11 to D3n in the present example with three strings are the same except for differences due to a sample spread.

In every strand 1 . 2 or 3 are the corresponding light-emitting diodes D connected in series with each other.

Each string further comprises a respective switch, for example, the switches S1, S2 and S3, with which a single strand 1 . 2 or 3 can be selectively switched on or off. In general, all strands are in terms of a required light intensity 1 to 3 switched on.

The number n of the light emitting diodes D included in each string is determined to approximate a supply voltage Vcc of a general power supply (not shown). The device V is connectable to the power supply device and carries out the control or regulation (activation and light emission, power supply) of the operation of the respective light emitting diodes D of the different strands 1 . 2 and 3 (or branches) on the basis of the supplied supply voltage Vcc (DC voltage).

The device V further includes for each strand 1 to 3 in each case an inductance or coil L1, L2 and L3, which is connected in each strand in series with the plurality of respective light-emitting diodes D. Each of the coils L1 to L3 is designed identically and comprises at least one winding with a plurality of turns, wherein preferably all coils (windings) have the same number of turns and also with respect to the wiring of the individual coils L1 to L3 each have a same sense of winding. This is in 1 indicated at the respective coils L1 to L3 by means of a point. Likewise, the respective coils windings with electrical conductors with a same conductor cross-section.

Furthermore, a magnetic core K is provided for the arrangement of the respective coils L1 to L3, which is arranged in such a way that all coils, ie the coils L1 to L3 of the strands 1 to 3 are applied to this magnetic core K or wound around this magnetic core K. The (in the 1 and 3 For clarity, hatched for clarity) magnetic core K thus represents a common for all coils L1 to L3 magnetic core, so that each coil L1 to L3, for example, the three in 1 shown strands 1 to 3 with each of the other coils via the magnetic field formed within the coils L1 to L3 and thus in the magnetic core K are interconnected (linked). In operation, each of the at least two strands takes 1 to 3 Power on, so that in each coil, a magnetic field (flooding) is established. It is thus formed by the respective flooding, which contributes to each coil, a common same-direction flooding and thus a common magnetic field. Unequal currents in the individual strands 1 to 3 also lead to unequal flooding in the respective coils L1 to L3.

As a result, on the one hand, the common magnetic field penetrates each coil L1 to L3, and on the other hand contributes each coil L1 to L3 with its own flux to the entire magnetic field and thus the entire magnetic flux.

The inductors or coils L1 to L3 are thus connected to one another via the magnetic field and the magnetic coupling by the common magnetic flux. On the other hand, the coils L1 to L3 as a result of their arrangement within the device V are also galvanically connected to each other (for example, via other components such as the light-emitting diodes D).

The device further comprises a switching device 4 , which is preferably provided in the form of a transistor, for example a field effect transistor FET. The switching device 4 is preferably at a common node of all strands 1 to 3 is connected to the one terminal, and is connected to the other terminal (eg, source) with a negative potential or ground potential of the general power supply device. A control terminal (gate) of the switching device 4 is with a control line 5 connected. By means of the control line 5 can the switching device 4 be brought into any predetermined switching state. Preferably, via the control line 5 the switching device 4 selectively and in accordance with a predetermined clock on and off, so that the totality of at least two strands 1 to 3 with LEDs D on or off or power control can be performed.

With a corresponding control of the switching device 4 over the control line 5 For example, a control influence in connection with a pulse width modulation PWM can be achieved. In this case, the strands 1 to 3 including the associated light-emitting diodes D and the coils L1 to L3 a clocked DC supplied. Since in this case, with respect to the arranged in the device V coils L1 to L3 currents are switched on and off by inductors, to protect the LEDs used in the circuit arrangement of the device V is a freewheeling element F parallel to all strands 1 to 3 and arranged in reverse polarity.

In an operation by means of a pulse width modulation PWM used frequencies of the drive can be in the range of 20 kHz. Also frequencies of about 70 kHz to 100 kHz can be used. At these frequencies, the flickering of the light emitting diodes is virtually imperceptible to the human eye.

The freewheeling element F, which may be provided for example in the form of a diode (freewheeling diode, protection diode), serves to protect against overvoltages and thus unauthorized high voltages, which arise as a result of switching off the coils L1 to L3 by their self-inductance.

With the circuit arrangement of the device V as shown in FIG 1 the possibility is achieved for all strands (or branches) of the circuit arrangement, each with series-connected LEDs D and thus by a common switching converter in conjunction with the switching device 4 and a possible PWM control on the control line 5 to achieve a balance of currents in the circuit arrangement, if, for example, by a copy scattering of the individual light-emitting diodes D in the respective strands 1 to 3 Uneven currents flow, so that a lesser load or an overload of a single strand can be largely excluded.

In this case, the light emitting diodes D in a series circuit per strand represent the load (with a capacitive component) for the switching converter, which in conjunction with the switching device 4 and the respective coils L1 to L3 is formed.

The coils (inductors) L1 to L3 applied or arranged on the common magnetic core K are coils wound in the same winding direction and with the same number of turns, so that identical and in-phase windings are formed and result in the same direction in the common magnetic core K. The number of coils preferably corresponds to the number of individual strands 1 to 3 (Branches of the circuit arrangement), so that in a corresponding manner depending on the number of strands, the number of coils is provided and the common magnetic core K is formed such that the number of coils can be supported and optimum magnetic coupling between the coils is ensured ,

As a result of the coils L1 to L3 arranged and connected in the same way and connected in the same way on the common magnetic core K, the magnetization energy in the magnetic core is approximately evenly distributed in the circuit arrangement of the device V with the same number of turns. This leads to approximately the same currents in the individual windings and thus also in the connected individual strands 1 to 3 the light-emitting diodes D, so over the magnetic coupling of the coils L1 to L3 and disturbing differences in the burning voltage of individual strands 1 to 3 can be compensated. In the coils L1 to L3 applied to the same common magnetic core, a DC current having a triangular component caused by the magnetic field buildup and degeneration in the common magnetic core occurs when driven by the switch means 4 (with turning on and off the voltage Vcc of the power supply device) is performed.

With a respective magnetic field change of the common magnetic field in the common magnetic core K, a certain amount of energy is made available per core volume for the coils L1 to L3 arranged thereon, which distributes themselves in an equal manner over the turns.

The present invention is not limited to the use of light-emitting diodes D as loads of the circuit arrangement of the device V and represents only one embodiment. Other loads, for example ohmic loads, are also conceivable instead of the plurality of light-emitting diodes if an electrical control device is required. to flow at approximately the same currents in different strands or branches of the circuit arrangement. In general, all types of loads can be controlled or operated, provided that these loads have to be operated with about the same current and then set in operation at the loads corresponding (even different) voltages.

Is in an arrangement according to 1 switched off by means of one of the switches S1 to S3 one of the strands, no current flows in this strand and the associated coil does not contribute to the common flux in the common magnetic core. In this case, the current then becomes equal split on the remaining active windings or coils. This also means an increase in current in the individual remaining strands and thus requires a control preferably via the circuit device 4 in the sense of an adaptation of the pulse-pause ratio (ie the PWM characteristics). In this case, a current detection can be provided by means of a corresponding sensor.

The electrical control device V described above thus represents a device for the low-loss dynamic distribution of currents in a network in conjunction with a switching converter. The network is formed by the corresponding strands with the respective series-connected LEDs D, for example, the strands 1 to 3 as shown in 1 , The electric control device may be applied to a lighting device in which a plurality of loads, for example, the light emitting diodes D, are provided in at least two strands having an equal number in each strand and connected in series with each other. The device is connectable to the plurality of light-emitting diodes.

According to 1 are in the circuit arrangement of the device V three strands 1 to 3 arranged in each case in series with each other connected light emitting diodes D and the associated coils L1 to L3. The strands are executed here similar. However, the present invention is not limited to this number of, for example, three strands, and an arrangement of respective coils having a common magnetic core may be formed in at least two strands or more than three strands. Thus, the number of strands is not limited and is determined only in connection with the performance of the power supply device to which the device V is connectable.

In this case, the increased number of coils is provided depending on the number of strings, and the common magnetic core K also includes the plurality of coils. Thus, in particular, the magnetic core K is designed to carry the number of strands corresponding number of coils or inductors, so that each coil is linked via the common magnetic field with each other coil.

Various types of arrangement of the coils on the common magnetic core K are in 2 shown.

As shown in 2a is merely simplified and shown schematically that on the common magnetic core Ka shown in simplified form, for example, four identical coils L1 to L4 are applied with the same winding sense and the same number of turns (ie in the same configuration). The representation in 2a serves to illustrate that the four coils L1 to L4 are arranged on the common magnetic core Ka and thus connected to each other via the common magnetic field.

Actual embodiments (examples) are in the 2 B and 2c shown in FIG 2 B an approximately circular magnetic core Kb is indicated, on which, for example, three identical coils (with respect to the sense of winding and the number of turns) are arranged. 2c shows the common magnetic core Kc, in which each leg carries two of four identical coils L1 to L4.

Specifically, the coils may be arranged side by side on the common magnetic core K or Ka to Kc. The individual windings of the coils can also be designed bifilar at two coils or multifilar at several coils, so that the coils are also layered on the common magnetic core (for example, on a leg thereof). The coils can also be successively stacked on the common magnetic core, which is about an arrangement according to 2 corresponds, where in 2c a pairwise stacking is shown.

Preferably, the coils L1 to L3 are multifilar in the sense of a desired optimal concatenation with the common magnetic field and a simplified or facilitated production, so that, for example, with one winding process several coils can be produced with good concatenation. In general, a bifilar or multifilar coil arrangement is superior to a single coil arrangement. The better the current balancing or the desired current balancing between the strings, the better the better the magnetic coupling of the coils on the common magnetic core, i. H. when all involved windings (coils) are actually flooded by substantially the same magnetic field.

In any case, the plurality, ie the at least two coils of at least two strings with loads (loads, for example LEDs) arranged on the common magnetic core, that they have the same number of turns and the same winding sense and are optimally linked together by the magnetic field. With the optimal concatenation via the common magnetic field, the desired compensation is achieved in the event of an unevenness of the phase currents occurring in the circuit arrangement without this measure. This means a uniform power supply to all loads, For example, the light-emitting diodes D, and thus also to a uniform illumination within the total number of light-emitting diodes (for example, a geometric light emitting diode array) and an improved light output of the same.

The arrangement of a plurality of coils on a common magnetic core can also be constructed as a solution with electrical isolation. In this case, transformers are used which are one of a switching element (such as the switching device 4 ) driven primary winding and according to the number of strands to be operated has an equal number of coils as secondary windings.

It is also possible, in addition to the potential-separated solution, depending on specific conditions, to carry out one or a certain number of coils in a different manner relative to the other coils. Thus, a winding with half the number of turns because of the same flooding over other coils with the same normal number of turns would lead to twice the current. By means of the arrangement described above can thus also be a strand or branch with half the operating voltage and operated with about twice the current.

The respective coils provided in the strands (windings of the inductors) L1 to L3, for example according to FIG 1 , represent both a component of the switching converter, by means of which the power control by the switching device 4 can take place, as well as components for providing a balance in terms of power distribution in the parallel strands or branches of the respective consumers. By means of the above arrangement is thus an up or down converter (English: boost converter, buck converter) is provided, the inductance (storage inductor) is formed by a plurality of co-directional winding or coils on a common magnetic core. In this case, one side (ie, one of the terminals in each case) of the plurality of coils lies on the switching device, like the switching device 4 according to 1 and the respective other terminals of the coils are connected to the consumers to be influenced with regard to the current distribution, ie form a common node with the respective terminal of the switching device 4 ,

Second embodiment

3 shows a second embodiment of the present invention.

According to 3 For example, consumers V11, V12, V13, V14 and V21, V22 and V23 to be fed are divided into two groups G1 and G2, so that in each group G1 and G2 a common magnetic core K1 or K2 for the respective consumers in the respective Group G1 or G2 is provided. The first magnetic core K1 is thus assigned to the first group G1 of the consumers V11, V12, V13, V14 having four strings or branches, while the second magnetic core K2 of the second group is assigned to the consumers V21, V22 and V23 having three strings or branches. The two magnetic cores K1 and K2 are not magnetically connected to each other. At the respective magnetic cores K1 and K2, the coils (inductors) L11, L12, L13 and L14 and L1, L22 and L23 are arranged. The number of respective coils L11, L12, L13 and L14 and L21, L22 and L23 corresponds to the number of strings in each group G1 and G2. Parallel to the strands of the arrangement according to 3 is a freewheeling element F connected.

According to this arrangement 3 This results in the current compensation (ie the desired current balancing) described above in connection with the first embodiment within each group.

For similar consumers and thus similar coils L11 to L14 and L21 to L23, the magnetic cores K1 and K2 can also be connected to each other for magnetic coupling to selectively achieve a current balance within the entire arrangement. The efficiency of the current compensation becomes better the better the magnetic coupling between the magnetic cores K1 and K2 is.

In differently designed coils L11 to L14 and L21 to L23 in the individual groups G1 and G2 and different consumers (each within a group are the same) can be operated with different conditions. The number of groups is not limited. Similarly, the number of in 3 specified consumers in each group by way of example only. The invention is not fixed to this configuration.

The present invention has been described with reference to embodiments in conjunction with the accompanying figures.

However, it will be understood by those skilled in the art that the structure of the present invention, as set forth in the foregoing Figures, and the reference numerals used to refer to the respective components and components, are not to be interpreted as limiting in the figures and the description and the exemplary disclosures. Thus, the invention is not limited to the indicated representation in the figures. Rather, all embodiments and variants are considered as belonging to the invention, which fall under the appended claims.

Claims (11)

Electrical control device connectable to a plurality of consumers (D, D11 to D1n, D21 to D2n, D31 to D3n) for controlling the supply of power to the consumers, the plurality of consumers being arranged in at least two strings ( 1 . 2 . 3 ) with in each case the same number of consumers connected in series, with a switching converter ( 4 , L1, L2, L3) having a number of inductances (L1, L2, L3), wherein in each strand an inductance is connected in series with the respective loads, and the inductances have a common magnetic core (K). Apparatus according to claim 1, wherein respective windings of the inductors (L1, L2, L3) are applied in the same winding sense on the common magnetic core. Apparatus according to claim 2, wherein the windings of the inductors (L1, L2, L3) have the same number of turns. Apparatus according to claim 2 or 3, wherein the windings of the inductors (L1, L2, L3) are stacked or stacked on the common magnetic core. Device according to one of claims 2 to 4, wherein the windings of the Induktivtäten (L1, L2, L3) are formed multifilar. Device according to one of claims 1 to 5, wherein the common magnetic core (K) is a closed magnetic core. Device according to one of claims 1 to 6, wherein the switching converter ( 4 , L1 to L3) a switching device ( 4 ) for controlling the power supply to the consumers. Device according to claim 7, wherein the switching device has a control connection ( 5 ) and the input signal at the control terminal is a PWM signal. Device according to one of claims 1 to 8, wherein parallel to the at least two strands, a freewheeling element (F) is connected. Device according to one of claims 1 to 9, wherein the consumers are light-emitting diodes. A lighting device comprising: - a plurality of light emitting diodes (D, D11 to D1n, D21 to D2n, D31 to D3n) arranged in at least two strings ( 1 . 2 . 3 ) are connected in series with each other with an equal number in each strand, and - an electrical control device (V) connectable to the plurality of light-emitting diodes according to one of the claims 1 to 10.

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