Abstract:
The invention relates to a power supply arrangement, in particular for supplying power to thin silicon rods in a reactor for producing polysilicon with the Siemens process, with inputs (L 1,  L 2,  L 3 ) for connection to a three-phase power grid, with outputs, grouped in three groups (A 11 -A 13,  A 21 -A 24,  A 31 -A 33 ) of outputs for supplying power to loads connected to the outputs, in particular the thin silicon rods, with three groups (S 1,  S 2,  S 3 ) of adjusting means for adjusting an electric voltage present at the outputs, and with three groups (U 1,  U 2,  U 3 ) of switchover means for switching between a parallel connection and a series connection of the outputs in one of the groups (A 11 -A 13,  A 21 -A 24,  A 31 -A 33 ) of outputs, wherein at least in one state of the power supply arrangement, each group (S 1,  S 2,  S 3 ) of adjusting means is connected to a group of outputs (A 11 -A 13,  A 21 -A 24,   A 31 -A 33 ) by way of a group of switchover means (U 1,  U 2,  U 3 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    (1) Field of the Invention 
         [0002]    The present invention relates to a power supply arrangement, in particular for supplying power to thin silicon rods in a reactor for producing polysilicon with the Siemens process, with inputs for connection to a three-phase power grid, with three groups of outputs for supplying power to loads connectable to the outputs, in particular the thin silicon rods, with three groups of adjusting means for adjusting an electric voltage applied at the outputs, and with three groups of switchover means for changing between a parallel connection and a series connection of the outputs of one of the groups of outputs, wherein at least in one state of the power supply arrangement, each group of adjusting means is connected to a group of outputs by way of a group of switchover means. 
         [0003]    An output in a power supply arrangement of this type is a pair of electrical terminals configured for connection of one or more serially connected loads. If a load is connected to the output, then in at least one state of the current supply arrangement, a current can flow from one terminal to the other terminal via the load. However, states of the current supply arrangement may also exist where current does not flow from one of the terminals of an output to the other terminal. A connection of one output may also be a connection of at least one additional output. 
         [0004]    If in one state of the current supply arrangement several outputs are connected in parallel, then this means that the outputs in this state of the current supply arrangement are connected to the same current source in the current supply arrangement. If loads are connected to the parallel-connected outputs, then these loads are also connected in parallel. 
         [0005]    Conversely, if in one state of the current supply arrangement several outputs are connected in series, then a voltage drop occurs in this state across all serially-connected outputs. If loads are connected to the serially-connected outputs, then a current flows from a first terminal of a first output of the series connection through the loads to a second terminal of a last output of the series connection. No current flows via the other terminals of the serially-connected outputs. 
         [0006]    (2) Description of Related Art 
         [0007]    The European patent application EP 1 947 545 A2 discloses in  FIG. 2   a  current supply arrangement for supplying power to thin silicon rods in a reactor in order to produce polysilicon with the Siemens process. Thin silicon rods are combined into rod pairs, forming the loads connected to the current supply arrangement. 
         [0008]    The current supply arrangement has three groups of outputs, wherein the outputs of these three groups can be connected in a parallel connection or a series connection. If the outputs of a group of outputs are connected in series, then the rod pairs connected to the outputs of this group are also connected in series. Conversely, if the outputs are connected in parallel, then the rod pairs are also connected in parallel. In addition to these three groups of outputs, the current supply arrangement has an additional output. Overall, 18 rod pairs can be supplied with electric energy by using a current supply arrangement according to  FIG. 2  of the European patent application EP 1 947 545 A2. 
         [0009]    The rod pairs are arranged in the reactor in form of three concentric rings, wherein three rod pairs are arranged in an inner ring, six rod pairs in a center ring, and nine rod pairs in an outer ring. A total of six rod pairs are supplied with electric energy via each of the three inputs of the three-phase current supply arrangement, which is realized by supplying electric energy from one phase to the three rod pairs of the inner ring and three rod pairs of the outer ring. This leads to a high degree of complexity of the group of adjusting means, to which these rod pairs are connected. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    It was therefore an object of the invention to provide a simple current supply arrangement of the aforedescribed type, which is suitable for supplying power to rod pairs arranged in a reactor in two concentric rings. In particular, the current supply arrangement should be suitable and configured to supply power to 18 rod pairs. 
         [0011]    This object is attained with the invention by grouping all outputs into three groups of outputs. 
         [0012]    With the current supply arrangement according to the invention, electric energy can be supplied to 18 rod pairs arranged in a reactor in two concentric rings. The partition can be performed such that a first group of outputs is provided for supplying power to the rod pairs of the inner ring, whereas the other two groups are provided for supplying power to the rod pairs of the outer ring. However, the use of the current supply arrangement according to the invention is not limited to this situation. 
         [0013]    A current supply arrangement according to the invention can be configured such that in at least one state of the current supply arrangement, each group of adjusting means is connected to exactly one group of outputs via exact the one group of switchover means. Preferably, this is the situation when the outputs of the group are connected in parallel. However, each group of adjusting means may preferably also be connected to an input via exactly one transformer. With this unambiguous association of the group of adjusting means, switchover means and outputs as well as the transformers, a simple control structure for controlling the power transmitted via the outputs is feasible. 
         [0014]    The current supply arrangement according to the invention may have at least one first group of outputs of the groups of outputs, wherein three outputs may be operated in a parallel connection or in a series connection. Two serially connected loads can then be connected to each output. Half of the voltage present at the respective output then drops across each load. Preferably, a current supply arrangement according to the invention has exactly one first group of outputs. However, according to the invention, all three groups of outputs may each have three outputs which can be operated in a series connection or in a parallel connection. 
         [0015]    In addition, a current supply arrangement according to the invention may have at least one second group of outputs of the groups of outputs, wherein two outputs can be operated in a parallel connection or in a series connection. Three loads can then be connected to each output. In a parallel connection of the outputs of the second group, the voltage drop is then one third of the voltage present at the output. Preferably, a power supply arrangement according to the invention has exactly two second groups of outputs. However, according to the invention, all three groups of outputs may have two outputs which can be operated in a series connection. 
         [0016]    The groups of adjusting means of a power supply arrangement according to the invention may have input-side terminals. These may each be connected to a tap of a secondary side of the transformer connected to the group of adjusting means. By way of the taps, different voltages can be applied on the input-side of the group of adjusting means. 
         [0017]    The groups of adjusting means may have a first output-side terminal and a second output-side terminal. Each output-side terminal may be connected to at least two input-side terminals via a power control device. With this type of connection of the output-side terminals, a voltage at the output-side terminals of the groups of adjusting means can be adjusted in two ways. A first step-wise adjustment of the voltage is possible by selecting the input-side terminal connected to the output-side terminal via a power controller. A second, preferably continuous adjustment is possible by selecting a firing angle of the power control device. In this way, continuously adjustable voltages can be applied to the output-side terminals of each group of adjusting means with a voltage follower control. 
         [0018]    Because the first output-side terminal of the power supply arrangement operates to supply power to the outputs in a parallel connection of the outputs and the second output-side terminal operates to supply power to the outputs in a series connection of the outputs, the voltage at the outputs of a group of outputs can be additionally varied. Whereas with a parallel connection of the outputs, a full maximum voltage is provided at the first output-side terminals of the corresponding group of adjusting means, with a series connection the maximum voltage at the outputs of a group of outputs is only a fraction of the voltage present at the second output-side terminal of the associated group of adjusting means. This fraction is determined by the number of serially connected outputs in the group. 
         [0019]    In a power supply arrangement according to the invention, each group of switchover means may have an input-side terminal. The input-side terminal is preferably connected to the first output-side terminal of the associated group of adjusting means. The voltage at the input-side terminals of the groups of switchover means can then be continuously adjusted. 
         [0020]    Each group of switchover means may have output-side terminals which are directly connected to the return line connection of the associated transformer, or which may be connected to the group of switchover means, optionally via controllable switching means, to the first input-side terminal or to a return line terminal of the associated transformer. 
         [0021]    A power supply arrangement according to the invention may be configured such that the second output-side terminals of the groups of adjusting means, the output-side terminals of the groups of switchover means and return line terminals of the transformers are connected to terminals of the outputs of the associated groups of outputs. 
         [0022]    In an advantageous embodiment of the power supply arrangement of the invention, each second output-side terminal of a group of adjusting means may be connected to a second output-side terminal of the associated groups of switchover means via a node in the associated group of switchover means. The second output-side terminal can then be indirectly connected to terminals of the outputs of the associated group of outputs by way of the output-side terminals of the groups of switchover means and the terminals to the return lines. 
         [0023]    A reactor according to the invention for producing polysilicon with the Siemens process has a power supply arrangement according to the invention and thin silicon rods arranged in the reactor, wherein the thin silicon rods are connected to the outputs of the current supply arrangement. Two serially connected thin silicon rods forming a load may be connected in one-to one correspondence to respective outputs of the first group, whereas three serially connected thin silicon rods forming a load may be connected in one-to one correspondence to respective outputs of the second group of outputs. Preferably, the power supply arrangement has one first group of outputs and two second groups of outputs. The rod pairs connected to the first group of outputs may be connected in an inner ring, and the rod pairs connected to the second groups may be connected to a second ring. 
         [0024]    A reactor of this type can be operated as follows:
       in a first step, a voltage is applied with a parallel connection to the outputs of the first group of outputs and the loads connected thereto, whereas no voltage is applied to the loads connected to the outputs of the second groups of outputs, and   in a later step, a voltage is applied with a series connection to the outputs of the first group of outputs and the loads connected thereto and to the outputs of the second groups of outputs and the loads connected thereto.       
 
         [0027]    During the first step, current flows through the loads connected to the outputs of the first group of outputs. The rod pairs heat up and lose a significant portion of their electrical resistance when reaching a known temperature. This is referred to as ignition of the rod pairs. With the voltage still applied, current continues to flow through the rod pairs. Half of the voltage applied across the associated output drops across each rod pair. 
         [0028]    The heat-up of the loads connected to the outputs of the first group radiates to the loads connected to the outputs of the second groups of outputs. These rod pairs are preheated by the radiant heat. In a step preceding the later step, voltage may be applied to the outputs of the second groups of outputs and the preheated loads connected thereto in a parallel connection. Because three rod pairs are connected to each output of the second group, the voltage drop across each rod pair is one third of the voltage across the output. However, this third is sufficient to further heat and also fire the preheated loads. During this time, a voltage may stay applied to the outputs of the first group of outputs and the loads connected thereto in a parallel connection. However, a voltage may also be applied during this time to the outputs of the first group of outputs and the loads connected thereto in a series connection. 
         [0029]    It is also feasible to apply a voltage to the outputs of the second groups of outputs and the loads connected thereto in series connection, while a voltage is applied to the loads connected to the outputs of the first group in a parallel connection. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0030]    Additional features and advantages of the present invention will become clear from the following description of an exemplary embodiment illustrated in the drawing. It is shown in: 
           [0031]      FIG. 1   a  schematic circuit diagram of a power supply arrangement according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0032]    The power supply arrangement illustrated in  FIG. 1  has three inputs L 1 , L 2 , L 3  connected to three transformers T 1 , T 2 , T 3  in a Delta connection. The secondary sides of the three transformers T 1 , T 2 , T 3  are connected in one-to-one correspondence to a group S 1 , S 2 , S 3  of adjusting means. A respective group U 1 , U 2 , U 3  of switchover means is connected to each group S 1 , S 2 , S 3  of adjusting means. In addition, a group of outputs is connected to each group S 1 , S 2 , S 3  of adjusting means and to each group U 1 , U 2 , U 3  of switchover means. A group H 1 , H 2 , H 3  of loads is connected to each group of outputs. 
         [0033]    During the operation of the power supply arrangement, a current supplying the loads of the group of loads flows via the transformers T 1 , T 2 , T 3 , the groups S 1 , S 2 , S 3  of adjusting means and the groups of the outputs. 
         [0034]    The transformers T 1 , T 2 , T 3  and the groups S 1 , S 2 , S 3  of adjusting means are constructed identically. They will be described in more detail with reference to the transformer T 1  and the group S 1  of adjusting means connected thereto. 
         [0035]    The secondary side of the transformer T 1  has four taps T 13 , T 14 , T 15 , T 16 . These taps T 13 , T 14 , T 15 , T 16  of the transformer T 1  are connected to input-side terminals S 101 , S 102 , S 103 , S 104  of the group S 1  of adjusting means. Within the group S 1  of adjusting means, the input-side terminals S 101 , S 102 , S 103  are connected in one-to-one correspondence to two corresponding power control devices S 11 , S 15 , S 12 , S 16 , S 13 , S 17  via a respective node, whereas the input-side terminal S 104  is connected to a power control device S 14 . The power control devices S 15 , S 16 , S 17  are connected to a first bus bar, while the power control devices S 11 , S 12 , S 13 , S 14  are connected to a second bus bar. The first bus bar is connected to a first output-site terminal S 105  and the second bus bar is connected to a second output-side terminal S 106  of the group S 1  of adjusting means. 
         [0036]    In the same manner, taps T 23 , T 24 , T 25 , T 26 , T 33 , T 34 , T 35 , T 36  of the transformers T 2 , T 3  are connected to input-side terminals S 201 , S 202 , S 203 , S 204 , S 301 , S 302 , S 303 , S 304  of the group S 2 , S 3  of adjusting means. Within these groups S 2 , S 3  the input-side terminals S 201 , S 202 , S 203 , S 204 , S 301 , S 302 , S 303 , S 304  are connected in the same manner to first output-side terminals S 205 , S 305  and second output-side terminals S 206 , S 306  via power control devices S 21 , S 25 , S 22 , S 26 , S 23 , S 27 , S 24 , S 31 , S 35 , S 32 , S 36 , S 33 , S 37 , S 34  and a first and a second bus bar. 
         [0037]    The first output-side terminal S 105  is connected to an input-side terminal U 101  of the associated group U 1  of switchover means, whereas the second output-side terminal is connected to a terminal A 11  of the first group A 11  to A 13  of outputs. Likewise, the first output-side terminals S 205 , S 305  of the groups S 2 , S 3  are connected to input-side terminals U 201 , U 301  of the associated group U 2 , U 3  of switchover means. The second output-side terminals S 206 , S 306  of the groups S 2 , S 3  are connected to terminals A 21 , A 31  of the groups A 21  to A 24 , A 31  to A 33  of outputs. 
         [0038]    In addition to the terminals A 11 , A 21 , A 31 , the groups of outputs have additional terminals A 12 , A 13 , A 22 , A 23 , A 24 , A 32 , A 33 . Each terminal together with another terminal of the same group is at least part of an output. The terminal pair A 11  and A 12  and the terminal pair A 12  and A 13  form the outputs of the first group of outputs. The terminal pair A 21  and A 22 , the terminal pair A 22  and A 23  and the terminal pair A 23  and A 24  form the outputs of the second group of outputs. The first and the third group of outputs have two outputs. The second group has three outputs. 
         [0039]    The terminals A 13 , A 24 , A 33  are connected to taps T 17 , T 27 , T 37  of the associated transformers T 1 , T 2 , T 3  via a return line. 
         [0040]    If the outputs are connected in series, the entire voltage across the second output-side terminal S 106 , S 206 , S 306  of the groups S 1 , S 2 , S 3  drops between the terminal A 11  and the terminal A 13 , the terminal A 21  and the terminal A 24 , and the terminal A 31  and the terminal A 33 . In this situation, no voltage must be present at the first output-side terminals S 105 , S 205 , S 206 . 
         [0041]    While the groups U 1 , U 3  of switchover means are constructed identically, the group U 2  is constructed differently. The reason herefor is that the groups U 1 , U 3  of switchover means are provided for the parallel connection of the two outputs of the first and third groups, whereas the group U 2  is suitable and configured for the parallel connection of the three outputs of the second group. 
         [0042]    In addition to the input-side terminals U 101 , U 301 , the groups U 1 , U 2  of switchover means have terminals U 102 , U 103 , U 104 , U 202 , U 203 , U 204  which are connected to the terminals A 11 , A 12 , A 13 , A 31 , A 32 , A 33 . As a result, a voltage can be applied in parallel to the outputs of the first and the third groups of outputs formed by the terminal pairs A 11 , A 12 ; A 12 , A 13  and/or A 31 , A 32 ; A 32 , A 33  via the terminals U 102 , U 103 , U 104 , U 202 , U 203 , U 204 . 
         [0043]    The terminals U 103 , U 303  are connected to the terminals A 12 , A 32  of the outputs and to the input-side terminals U 101 , U 301  via interconnected first coils of coupling means U 12 , U 32 . A voltage at the input-side terminals U 101 , U 301  is therefore also present at the terminals U 103 , U 303  and the terminals A 12 , A 32 . 
         [0044]    The terminals U 102 , U 302  are connected to the terminals A 11 , A 31  and to the terminals U 104 , U 304  via interconnected switches U 11 , U 31  and second coils of the coupling means U 12 , U 32 . 
         [0045]    The terminals U 104 , U 304  are also connected to the terminals A 13 , A 33  and to the return line terminals T 17 , T 37  of the transformers T 1 , T 3 . 
         [0046]    When the controlled switches U 11 , U 31  are closed, the terminals U 102 , U 302  and the terminals A 11 , A 31  are connected to the return line terminals T 17 , T 37  of the transformers T 1 , T 3 . The outputs of the first and the third groups of outputs formed by the terminal pairs A 11 , A 12 ; A 12 , A 13  and/or A 31 , A 32 ; A 32 , A 33  are then connected in parallel. No voltages must be present at the second output-side terminals S 106 , S 306 . 
         [0047]    The coupling means U 12 , U 32  are transformers, wherein currents to the parallel-connected outputs flow through the first coil and a current from one of the outputs flow through the second coil. With a suitable design of the transformer familiar to a person skilled in the art, the sum of the currents to the parallel-connected outputs can be set to be twice the current from the one output. 
         [0048]    The group U 2  of switchover means is different because the three outputs of the second group of outputs can be connected in parallel, whereas two outputs can be connected in parallel in the other groups U 1 , U 3 . In addition to the input-side terminal U 201 , the group U 2  has terminals U 202 , U 203 , U 204 , U 205  which are connected to the terminals A 21 , A 22 , A 23 , A 24  of the outputs of the second group. The terminals U 202 , U 204  and hence the terminals A 21 , A 23  are connected via a controlled switching means U 21  with the input-side terminal U 201 , so that when the switching means U 21  is closed, the same voltage is present at the terminals A 21 , A 23  as at the first output-side terminal S 205  of the group S 2  of adjusting means. 
         [0049]    The terminal U 205  is connected to the terminal A 24  and to a return line terminal T 27  of the transformer T 2 . The terminal A 24  therefore always has the potential of the return line terminal T 27 . The terminal U 203  is connected to the terminal A 22  and via a control switchover means U 22  to the terminal U 205  and hence also to the return line terminal T 27 . When the switching means U 22  is closed, the terminal A 22  is also at the potential of the return line terminal T 27 . 
         [0050]    If the outputs of the group A 2  formed by the terminal pair A 21 , A 22 , the terminal pair A 23 , A 22 , and the terminal pair A 23 , A 24  are connected in parallel, then the switching means U 21 , U 22  are closed. If the outputs of the group A 2  are connected in series, then the switching means are open, so that the voltage at the second output-side terminal S 206  drops across the series connection of the outputs. 
         [0051]    The group U 2  of switchover means also includes coupling means U 25 , U 26  which operates to ensure that the currents through the outputs have always identical magnitude.