Abstract:
A device for controlling a plurality of electrical consumers to which a constant control current is applied at control nodes. A transformer unit to which a regulated and/or constant current having a predetermined frequency is applied at the input end comprises at least one first and a second winding at the output end which have a common tap, a first circuit branch forming a first control node for a first electrical consumer is associated with the first winding, and a second circuit branch forming a second control node for a second electrical consumer is associated with the second winding. Furthermore, the first and the second circuit branch each have a magnetically interacting pair of reactors which are wound in opposite directions relative to each other, and a first reactor of said pair is connected to the first control node via rectifying means, while a second reactor of the same pair is connected to the second control node via rectifying means. The reactors that are connected to one of the control nodes are wound in opposite directions. The pairs of reactors are magnetically coupled, in particular having a common reactor core.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a device for controlling a plurality of electrical consumers according to the preamble of the main claim. Electrical consumers may have LEDs in the form of strands in particular. On the other hand, the invention includes and claims the act of providing these electrical consumers in the form of electrical consumers which do not have semiconductor-based lamps, in particular no LEDs, and instead are implemented as batteries (in which case the present invention is then embodied to control a plurality of such batteries as a charging device) and additionally or alternatively, the electrical consumers have electric motors, or again alternatively, they may have a plurality of galvanic devices to which a constant electrical current is supplied. 
         [0002]    With regard to the state of the art, reference should first be made to the LED technology. 
         [0003]    In particular for the purpose of manufacturing intensely bright lights, (high-performance) LEDs in strand form are combined as a series connection, to then be able to deliver the cumulative light intensity (on a suitable carrier).  FIG. 2  illustrates such an arrangement, in which a first control node CH 1  and a second control node CH 2  each represent the switching point for a series connection of a plurality of LEDs (10 per strand here). 
         [0004]    The need for achieving a uniform light output of each LED leads to the fact that they are arranged as a series connection in the manner described here; a typical voltage drop of approximately 3.2V with a white LED then results in voltages of approximately 32V being applied per strand in the arrangement illustrated in  FIG. 2 . From the goal of not exceeding safety limits for low voltages, this leads to the result that multiple strands are carried in parallel, for example, with two strands in the manner illustrated in  FIG. 2 , when orders of magnitude of 15 to 20 LEDs are exceeded. 
         [0005]    However, component tolerances and other manufacturing-related deviations result in the fact that, in the absence of separate measures, parallel circuits of multiple strands will develop voltage differences, the result being an uneven current distribution among the individual strands. This leads to an irregular brightness of the respective LEDs in an advantageous manner and leads to disadvantages in terms of the lifetime of the lamps. 
         [0006]    Accordingly, to achieve a uniform luminous efficiency of parallel-connected strands, each having a plurality of LED lamps, it is customary in the state of the art to connect a current regulator upstream from each strand to adjust and/or regulate the current (I 1  in strand  1 , I 2  in strand  2  in  FIG. 2 ) flowing in the strand at the same level. 
         [0007]    However, this is complicated because a separate current regulating unit is required for each strand, so that there is a demand for a simplified current regulation for a plurality of parallel strands of LED lamps provided in the form of a series connection, in particular in the field of large-scale manufacturing technology and/or consumer applications. Furthermore, this basic demand exists not only for the LED lamps, which are used only for the context of this problem but instead there is also such a demand for any consumers, typically those such as batteries (to be charged) which receive a constant (regulated) current, electric motors (in particular stepping motors) or galvanic systems. All these consumers as well as additional electrical consumers which are typically operated at a constant current are considered to be “electrical consumers” in the remaining text in the sense of this invention, wherein a preferred implementation form of the invention excludes semiconductor-based lamps, in particular LEDs, from the invention. 
         [0008]    The object of the present invention is therefore to simplify a generic device for controlling a plurality of electrical consumers, in particular to reduce the structural complexity and/or hardware complexity, while at the same time providing a circuit which makes it possible to apply a current to the plurality of electrical consumers and to do so in an energy-efficient manner with a minimal power loss. 
       SUMMARY OF THE INVENTION 
       [0009]    This object is achieved by a device for controlling a plurality of electrical consumers to which a constant control current is applied at control nodes. A transformer unit to which a regulated and/or constant current having a predetermined frequency is applied at the input end comprises at least one first and a second winding at the output end which have a common tap, a first circuit branch forming a first control node for a first electrical consumer is associated with the first winding, and a second circuit branch forming a second control node for a second electrical consumer is associated with the second winding. Furthermore, the first and the second circuit branch each have a magnetically interacting pair of reactors which are wound in opposite directions relative to each other, and a first reactor of said pair is connected to the first control node via rectifying means, while a second reactor of the same pair is connected to the second control node via rectifying means. The reactors that are connected to one of the control nodes are wound in opposite directions. The pairs of reactors are magnetically coupled, in particular having a common reactor core. 
         [0010]    It is advantageously provided according to the invention that the total current which is kept constant and/or regulated and applied at the primary side is divided between two single individual currents at the secondary side of a main transformer (transformer unit and/or upstream device), it is preferable to provide for the division to be into equal individual currents on the secondary side through suitable identical design of the number of windings (winding numbers) of the windings on the secondary side, such that by adjusting the transmission ratio, a different adjustment may also be made. 
         [0011]    According to the invention, a pair of throttles in the manner of a current transformer is now provided in each of the circuit branches on the secondary side, said pair consisting of oppositely wound throttles, which cooperate magnetically with one another (these throttles being provided on a common throttle core, for example). Rectifier means, e.g., a diode for half-wave rectification, are then connected downstream from these throttle coils in the direction of the first and/or second control nodes for the electrical consumers ( FIG. 2 ), such that a first throttle of the throttle pair is connected in this way to the first control node and the (oppositely wound) second throttle coil of the pair is connected to the second control node via the rectifier means. Accordingly, for the second circuit branch, the first throttle is connected to the first control node and the second throttle is connected to the second control node, each being rectified, such that the throttles are wired, so that throttles connected to one control node (i.e., one of each of the two pairs) are also oppositely wound. 
         [0012]    Since the throttle pairs are also magnetically linked to one another, for example, (all of them) also being provided on the same throttle core, it is advantageously achieved through such a device that each throttle pair in the manner of a current converter divides the current for the half-waves (such that in the preferred case of the same number of windings, this ratio amounts to 1:1, whereas with different numbers of windings, the currents are inversely proportional to the transmission ratio in the throttle pair). 
         [0013]    The antipole design (i.e., the opposite windings of the individual throttles of a throttle pair on a common core) advantageously results in the magnetic fluxes of the windings canceling one another out via the signal characteristic. With regard to the intended current regulation for a plurality of electrical consumers, for example, for controlling the control nodes CH 1  and/or CH 2  ( FIG. 2 ) and a voltage difference in these strands due to components and/or tolerance, this advantageously leads to the result that the currents introduced by the first and/or second circuit branch into the control nodes still remain constant, just as before, while a voltage difference between CH 1  and CH 2  magnetizes the core. However, since a suitably repolarized voltage difference occurs with a following half-wave, there is a demagnetization and/or remagnetization that occurs for the core. 
         [0014]    Accordingly, for implementation of the invention, a respective throttle pair is to be designed and embodied with a respective absolute number of windings per coil according to a maximally occurring voltage difference between the strands and/or a desired maximal deflection of the core (taking into account its geometry). 
         [0015]    In the further embodiment according to the invention, this even makes it possible for a control node (and/or a respective electrical consumer) to be short-circuitable by switching a short-circuit to ground (the current thereby increases only by its high-frequency component, which would otherwise be short-circuited by a respective filter capacitor. However, in such a case, the voltage supplied by the main transformer would be only half as great, so then only half the power would be consumed, based on the output current). 
         [0016]    It is also advantageous that the principle according to the invention is not limited to providing a throttle pair for each circuit branch and/or for each control node. Instead the output signal of a throttle pair can be used according to the refinement and in the manner of a cascade to control two additional throttle pairs in a suitable manner in turn so that in this way the number of control nodes to be controlled (and also the electrical consumers provided at these control nodes) is increased accordingly. As a result, n electrical consumers may each receive a constant current (and/or an ideally equalized) control current with n−1 divider transformers (wherein such a divider transformer provides two throttle pairs on one common core). 
         [0017]    As a variant to this cascaded embodiment of the invention, it is provided according to the invention (and has also been claimed independently) to provide an embodiment in the manner of a paired coupling of neighboring channels for the respective control nodes, in which a first throttle of a first throttle arrangement is connected downstream from the first winding of the transformer unit on the secondary side, this embodiment being connected to the first of the control nodes via rectifying means, and a third throttle is connected downstream from the first throttle arrangement, which is connected to the second of the control nodes via rectifier means. However, a second throttle of the first throttle arrangement is connected downstream from the second winding of the transformer unit on the secondary side and is connected to the first of the control nodes via rectifier means, and a fourth throttle is connected downstream from the first throttle arrangement and is connected to the second of the control nodes via rectifier means. According to the invention, an oppositely wound throttle of a second throttle arrangement is connected upstream from the second and fourth throttles, such that this second throttle arrangement is connected to the two individual throttles between the first and/or second winding on the secondary side and the first throttle arrangement. The throttles of the second throttle arrangement are advantageously wound in opposite directions from one another according to the invention, likewise with the throttles of the first throttle arrangement which are connected to a respective one of the control nodes being wound in opposite directions from one another (i.e., for example, the first throttle and the second throttle of the first throttle arrangement, which are connected to the first control node). In addition, the throttles of the respective throttle arrangements are also advantageously interconnected magnetically according to the invention, especially advantageously being provided on a common throttle core. 
         [0018]    In an inventive refinement of this variant of the invention, it is also possible to galvanically separate the respective control nodes (and/or the respective circuit branches, i.e., throttles of the first and/or second throttle arrangements connected upstream from the control node). To this end, the transformer unit has a plurality of first and second windings on the secondary side, each being assigned to these branches and separated from one another and/or insulated from one another. 
         [0019]    According to an especially favorable variant of the invention, for which protection is claimed independently, only one winding is present on the secondary side of the main transformer. Here again, providing a throttle pair (magnetically linked together) in the manner described here also leads to the desired result, but with such a simplified (and asymmetrical) topology, one must ensure that the magnetization of the core occurring due to voltage differences is suitably demagnetized. Within the scope of this aspect of the invention, it is therefore advantageous to provide a demagnetizing unit with an auxiliary winding, which leads to a demagnetization potential, more preferably with the help of a (bridge) rectifier or this auxiliary winding with a center tap and two-way rectification, which thus causes the demagnetization of the core; in the exemplary embodiment described above, this was accomplished through the alternating half-waves in a normal-mode configuration and/or a center tap of the secondary winding. 
         [0020]    Within the scope of the invention, it is preferable to implement the plurality of electrical consumers according to the invention not as LEDs, but instead to provide as electrical consumers only those consumers which do not have any semiconductor-based lamps, in particular no LEDs. It is especially preferred according to the invention to provide a plurality of (rechargeable) batteries as the plurality of electrical consumers, such that in this case the device according to the invention may be implemented as a charger. Alternatively, it is provided within the scope of preferred implementations of the invention to provide the plurality of electrical consumers in the form of a plurality of (electric) motors, in particular as stepping motors, which receive a constant current in the manner according to the invention. Furthermore, according to the invention, it is provided within the scope of preferred further embodiments of the invention that the plurality of electrical consumers is to be embodied as devices for galvanics and/or galvanic treatment of workpieces which receive the constant current in the manner according to the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    Additional advantages, features and details of the invention are derived from the following description of preferred exemplary embodiments as well as on the basis of the drawings, which show: 
           [0022]      FIG. 1  a schematic wiring diagram of the device for controlling a plurality of electrical consumers according to a first exemplary embodiment of the invention; 
           [0023]      FIG. 2  a schematic line diagram to illustrate two electrical consumers provided parallel to one another; 
           [0024]      FIG. 3  a modification of the exemplary embodiment of  FIG. 1  by a short circuit and/or dimmer unit assigned to one of the two control nodes; 
           [0025]      FIG. 4  a further embodiment of the exemplary embodiment of  FIG. 1  in a cascaded two-stage system of throttle pairs for controlling four electrical consumers; 
           [0026]      FIG. 5  a variant of the invention with only one winding of the main transformer on the secondary side such that the throttle pair assigned to the first and/or second control node(s) additionally cooperates with an auxiliary winding for demagnetization; 
           [0027]      FIG. 6  an embodiment of the invention as a variant of  FIG. 4 , in which, instead of a cascaded system, a paired coupling of neighboring channels is performed and 
           [0028]      FIG. 7  a further embodiment of the exemplary embodiment of  FIG. 6  in which separate first and/or second windings of the (main) transformer on the secondary side are provided for each respective channel of a control node in order to separate the circuit branches thereby formed from one another. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]      FIG. 1  illustrates the essential components of the first exemplary embodiment of the invention. A pair of secondary windings  12 ,  14 , which are joined to one another via a center tap  13  and form circuit branches  16  and/or  17 , is formed on the secondary side of a main transformer  10 . A throttle pair  20  consisting of a pair of oppositely wound throttles  24 ,  26  on a common core are provided in the upper circuit branch  16  (the dots in the wiring diagram indicate the direction of winding in a manner which is otherwise known). Similarly, a throttle pair  22  consisting of the individual oppositely wound throttles  28 ,  30  is provided for the second circuit branch  18 . In the present exemplary embodiment with identical secondary windings  12 ,  14  with regard to the number of windings as well as with the same number of windings of the throttles  24  to  30 , there is thus a symmetrical arrangement to this extent. All of the individual throttles  24 ,  26 ,  28 ,  30  are formed by means of a common throttle core and cooperate magnetically to this extent. 
         [0030]    As further illustrated by the diagram in  FIG. 1 , one output (pole) of the throttle  24  is connected to the first control node CH 1  via a rectifier diode  32  ( FIG. 2 ), such that this control node is connected to ground (GND) across a filter capacitor  40 . The second throttle  26  of the first throttle pair  20  is connected to the control node CH 2  via a corresponding rectifier diode  36 ; this control node also has a high-frequency connection to ground across a filter capacitor  42 . 
         [0031]    Similarly and symmetrically with the first throttle pair  20 , the individual throttles  28 ,  30  of the second throttle pair  22  lead over rectifier diodes (rectifier means)  34 ,  38  to the control nodes CH 1  and/or CH 2 . It can be seen from the diagram in  FIG. 1  that the individual throttles (e.g.,  24 ,  28  for CH 1 ) leading to a control node are also wound oppositely from one another (likewise the individual throttles  26 ,  30  with regard to CH 2 ). 
         [0032]    During operation, the device shown here is supplied with a regulated and/or constant primary current on the primary side (in the manner of a conventional upstream device), such that this primary current then flows alternately in the secondary windings  12 ,  14  and/or in the branches  16  and  18  thus formed, depending on which half-wave is prevailing. The respective throttle pairs  20  and/or  22  then act in the manner of a current transformer, such that the current in branch  16  is divided among the throttles  24 ,  26  (at an assumed winding ratio of 1:1). The magnetic fluxes of the windings cancel one another due to the opposing polarity. A similar situation applies to throttle pair  22  in branch  18 . It is advantageously found that although a voltage difference from CH 1  to CH 2  (each relative on ground) produces magnetization of the core, this is compensated and/or canceled with a subsequent repolarized half-wave. 
         [0033]    In the exemplary embodiment shown here of a frequency of the applied current in the range between approximately 100 and 200 kHz (a range between 30 and 500 kHz is conceivable) and a maximum voltage at CH 1  and/or CH 2  in the range between approximately 40 and 50V (usually corresponding to 10 to 15 LEDs per strand), the throttles  24  to  30  have typical winding numbers from a few up to hundreds. Filter capacitors  40  and/or  42  are within the range of 1 μF to 10 mF. 
         [0034]    In a refinement of the exemplary embodiment of  FIG. 1 , it is possible to modify the number of windings of the throttles, such that the number of windings must be the same for the respective half-waves to one control node, i.e., the number of windings of the throttle  24 =the number of windings of the throttle  28 , and the number of windings of the throttle  26 =the number of windings of the throttle  30 . The ratios of these numbers of windings to one another then defines the ratio of the currents in the control nodes, i.e., winding ratio of throttle  24  to winding ratio of throttle  26 =I 2  (in CH 2 ):I 1  (in CH 1 ). 
         [0035]      FIG. 3  illustrates a preferred and advantageous modification of the exemplary embodiment of  FIG. 1 . With otherwise the same components, a short-circuit unit is connected downstream from the throttles  26  and/or  28  for the node CH 2 , said short-circuit unit consisting essentially of an FET  50  as a switching element controlled at its gate  52 , such that decoupling diodes  54 ,  56  are assigned to the throttle outputs. 
         [0036]    Then a clocked and/or periodic and/or modulated control of the gate terminal  52 , for example, permits dimming of the LED strand connected at CH 2 , in that a short-circuit to ground takes place in accordance with the “on” time of the FET  50 , and this portion of the current, which is tapped off to ground, is no longer available for the CH 2 . 
         [0037]    The transistor  50  also permits voltage regulation, e.g., by the fact that the transistor  50  influences the charging and/or discharging performance of the capacitor  42  (for example, between two control values) through its switching behavior. If the modulation and/or an on:off pulse duty factor at the switching input  52  of the transistor  50  is/are altered, the strand current ( 12  to CH 2  here) can be adjusted suitably between 0 and 100% preselected rated value. The current in the other strand (CH 2 ) remains unchanged in this configuration as long as the current supplied by the main transformer  10  remains constant. 
         [0038]    If in a variation of the principle of  FIG. 3 , the filter capacitor is shifted to the primary side (not shown) of the main transformer, then a simplification in the technical circuitry, namely removal of the capacitors, is possible on the secondary side such that the short-circuit switch (transistor  50 ) can then be connected directly to the output even without the decoupling diodes shown ( 54 ,  56 ). 
         [0039]      FIG. 4  illustrates another modification in the form of a cascade. 
         [0040]    Additional throttle pairs  60 ,  62 ,  64 ,  66  are provided here, such that the throttle pairs  20 ,  22  sit on a common core (in continuation of the exemplary embodiment of  FIG. 1  in a cascaded form), ditto for the throttle pairs  60 ,  62  having a common core and throttle pairs  64 ,  66  having a common core. The individual throttles of the throttle pairs  60  to  66  are again wound oppositely, and in the exemplary embodiment of  FIG. 4 , a separate short circuit according to  FIG. 3  is assigned to each strand (thus control nodes CH 1  to CH 4 ), so there is the greatest possible flexibility in wiring and/or modulation of the gate terminals  70  to  76 . 
         [0041]    If the throttle pairs  20 ,  22  as well as  60 ,  62  and  64 ,  66  are each interpreted as divider transformers, then a current regulation for a total of four strands and/or control nodes can be implemented with a total number of three divider transformers, or an implementation of n strands by n−1 divider transformers in generalized form. 
         [0042]    The principle shown here is possible with any normal-mode main converter circuits including half bridge, full bridge, resonant converter, M circuit, etc. 
         [0043]    For example, if the respective diodes are reversed in polarity as an example of an output, then a negative output voltage is applied at the corresponding control node and/or a negative output current flows. This current corresponds in amount to the positive current and can be adjusted as described above by stipulating corresponding transmission ratios. For example, if the polarity of the diodes ( 70 ,  72 ) is reversed for the control node CH 4  ( FIG. 4 ), then CH 4  is negative with regard to current and voltage accordingly. The polarity of the decoupling diodes ( 74 ,  76 ) should also be reversed for the switching transistor ( 50 ) in this branch, in which case this short-circuit switch would then be implemented as a P channel transistor. 
         [0044]    A current flows here through the upper winding ( 64 ), then the same current also flows through the lower winding of the pair ( 66 ), but in the opposite direction, for example, during the positive half-wave. Since these two windings have the same direction of winding but the currents are now opposite from one another, the principle described above is applicable. In the preceding divider stage (windings  20  and/or  22 ), the magnetic fluxes are added up and the windings  20  (lower winding) and  22  (lower winding), the direction of winding and the currents are in opposition and advantageously create the balance with the current in the winding  20  (above) according to the invention. 
         [0045]    It follows that the absolute current division is maintained in the manner provided according to the invention again in this case of an output with a reversed polarity. 
         [0046]      FIG. 5  illustrates another modification of the basic principle of  FIG. 1 , but in a further simplification, this turns away from the normal-mode principle of  FIG. 1  (in which both half-waves of the main transformer signal are advantageously utilized and in particular can also be used for demagnetization). In a further simplified exemplary embodiment of  FIG. 5 , the secondary side has only one winding  80 , downstream from which a throttle pair (oppositely wound)  82 ,  84  on a common core is connected and in turn leads over rectifier diodes  32 ,  34  to the control nodes CH 1 , CH 2 . Again, filter capacitors  40 ,  42  ensure a high-frequency ground connection. 
         [0047]    However, since there is a magnetization of the throttle core (which would not be demagnetized in the half-wave of the opposite polarity, as with the normal-mode circuit described above) due to the single-cycle implementation of  FIG. 5  and the potentially irregular voltages on CH 1  and/or CH 2 , a demagnetization is implemented in the form of an auxiliary winding  86  connected to a bridge rectifier  88  and a filter capacitor  90  to an auxiliary potential U hilf . 
         [0048]    The demagnetizing winding  86  may also be fed back to the primary side (with appropriate insulation). 
         [0049]    The principle illustrated in  FIG. 5  functions with single-cycle flux converters as well as flyback converters. With all types of flux converters (including normal-mode), a throttle with a demagnetizing diode also sits between the rectifier and the filter capacitor. The embodiment according to  FIG. 5  can also be refined by means of the regulation and/or dimming of  FIG. 3 . 
         [0050]      FIGS. 6 and 7  show another implementation of the invention which represents a variant through coupling of neighboring channels in comparison with the cascaded design of the invention according to  FIG. 4 . 
         [0051]    In concrete terms the transformer unit  10  again has two windings  12  and/or  14  on the secondary side which have a shared tap to ground GND. 
         [0052]    As also shown from the diagram in  FIG. 6 , each of the windings  12 ,  14  leads to one of the four control nodes CH 1  to CH 4 , which in turn, as in the manner described above, offer a current division and/or current limitation for electrical consumers (not shown), which can be connected there. To be more specific, with regard to the control nodes CH 1 , a throttle pair  70  (referred to as TR 3 -A and TR 3 -B in the wiring diagram) is connected upstream as a rectifier means via diodes D 1 , this throttle pair sitting on a common core and wound oppositely from one another. Two other individual throttles of a throttle pair  72  (TR 3 -C and TR 3 -D in the wiring diagram) are also part of the same throttle arrangement, sit on the same core and to this extent form part of a branch directed at the second control node CH 2  (again via rectifiers D 2 ). A throttle pair of a second throttle arrangement is connected upstream from the throttle pair  72 , a first throttle TR 2 -A leading to the first winding  12  on the secondary side and a second throttle TR 2 -B of the pair  80  leading to the second winding  14 . 
         [0053]    With regard to a further throttle arrangement consisting of throttle pairs  74  (for the third control node CH 3 ) and  76  (for the fourth control node CH 4 ) the exemplary embodiment of  FIG. 6  is designed symmetrically (based on the first throttle arrangement with the pairs  70 ,  72 ). Again the throttle pairs  74 ,  76  sit on a common core. Throttles of a throttle pair  82  are connected upstream from the throttle pair  74  such that the throttle pair  82  together with the throttle pair  80  forms a separate throttle arrangement (again on a common core) as described above. 
         [0054]    The respective throttle arrangements  70 ,  72  and  74 ,  76  as well as  80 ,  82  have a transmission ratio of 1:1. As a result a current I 1  to the first control node CH 1  is equal to the current I 2  to the second control node CH 2 . The additional throttle arrangements are designed accordingly, such that the throttle arrangement (transformer)  80 ,  82  ensures that I 2 =I 3 , and the throttle arrangement  74 ,  76  (transformer) ensures that I 3 =I 4  accordingly. 
         [0055]    As a result, it holds that I 1 =I 2 =I 3 =I 4 , so that each output current in one of the control nodes CHi (i=1 to 4) has a quarter of the value predetermined by the main transformer  10  (and/or its control on the primary side). 
         [0056]    The wiring diagram in  FIG. 6  shows that the transformer with the throttle pairs  80 ,  82  acts in principle like the throttle arrangement with the throttle pairs  20 ,  22  in the exemplary embodiment of  FIG. 4 . Fundamentally, windings that operate with the same phase angle of the input signal (i.e., the upper or the lower individual throttle of the pairs  80 ,  82  in  FIG. 6 ) are formed with opposite directions of winding. This is also true of individual windings leading to a shared control node, as is the case for the individual throttles of the pair  70 ,  72 , etc. 
         [0057]    The circuit principle of the exemplary embodiment of  FIG. 6  can also be expanded to any desired number of other channels. Like the principle described above, n−1 divider transformers (i.e., throttle arrangements in the sense described above) are necessary for n output channels, as in the exemplary embodiment of  FIG. 4 . It is likewise possible for the principle of the invention of  FIG. 6  to include individual dimming by channels via additional decoupling diodes as well as a short-circuit switch (reference numerals  50 ,  52  in  FIG. 4 ). 
         [0058]    If an output signal (control node) has one current value that is different from the others, then the transmission ratio of the throttle arrangements connected to the respective control node is to be adjusted, wherein the aforementioned rules are applicable. For example, if a different current value flows in the node CH 2  in the circuit of  FIG. 6  than in the nodes CH 1 , CH 3 , CH 4 , then the transmission ratio of the throttle pair 80:82 must be the same as the transmission ratio of the throttle pair 72:70 in order to set a different current I 2 . 
         [0059]    Within the context of the preferred refinements of the invention, it is also possible to combine the principles of the exemplary embodiment of  FIG. 4  (cascading) and/or of  FIG. 6  (paired wiring) with one another. For example, it is possible that one output (control node) of the circuit of  FIG. 6  is divided with another distributor transformer (throttle arrangement) into two channels, as shown in  FIG. 1 . Likewise, one output (control node) of the circuit from  FIG. 4  may supply the arrangement according to  FIG. 6 , for example, and then this output may be divided among four channels. 
         [0060]      FIG. 7  shows a variant of the exemplary embodiment of  FIG. 6 , wherein the same reference numerals denote corresponding matching circuit components. In contrast with  FIG. 6 , the current divider circuit on the secondary side is divided into a plurality of circuit branches separated (galvanically) from one another, channel by channel, such that each circuit branch is assigned to one of the control nodes for the consumers to be allocated and each has a (separate) winding pair of the main transformer on the secondary side, referred to in the example of  FIG. 7  as  12   i ′ and/or  14   i ′ (where i=1 to 4 according to the respective circuit branch). 
         [0061]    Due to this division of the main transformer  10  into a plurality of mutually insulated secondary windings, there is a magnetic decoupling of the four channels shown. A similar phase angle is to be ensured for each channel according to the allocation and design of the windings  12 ,  14  of  FIG. 6  on the secondary side.