Abstract:
A current supply arrangement with p first current supply devices and a second current supply device, n first transformers having a secondary winding with several taps. The secondary windings of each first transformer in each first current supply device are connected with one another via a power controller at a first node. The first node together with a tap for a reference potential of the at least one secondary winding of the first transformer, to which the first current supply device is connected, forms a first output, to which a series connection of loads, in particular polysilicon rods in a reactor for producing polysilicon according to the Siemens process, are connected, wherein the second current supply device has at an input with n terminals and q converter groups for converting n-phase AC current into m-phase AC current and the input is connected with the q converter groups.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    (1) Field of the Invention 
         [0002]    The present invention relates to a current supply arrangement with p first and at least one second current supply device,
       wherein the current supply arrangement comprises n first transformers,   wherein each transformer includes at least one secondary winding with several taps,   wherein at least two first taps of the secondary winding of each transformer in each first current supply device are connected with one another via a power controller at a first node,   wherein the first node of each current supply device together with a tap for a reference potential of the secondary winding of the transformer, to which the first current supply device is connected, forms a first output, to which a series connection of loads, in particular polysilicon rods in a reactor for producing polysilicon according to the Siemens process, can be connected,   wherein the at least one second current supply device has an input with n terminals and q converter groups for converting n-phase AC current into m-phase AC current and the input of the second current supply device is connected with the at least one converter group,   wherein the at least one second current supply device has an output with q*m+1 terminals which are connected inside the at least one second current supply device with terminals of the converter group,   wherein the circuit arrangement comprises p first switching groups,   which each have an output with at least q*m+1 terminals, to which the loads or a portion of the loads can be connected, which can be connected in series to the first current supply device,   which each have a group of at least q*m+1 controllable switching means, wherein the switching means of one group in a dosed state connect the terminals of the output of the at least one second current supply device with the terminals of the output, and   which have a control input which is connected to the control terminals of the switching means,   wherein n, m, p and q are natural numbers,       
 
         [0014]    The term multi-phase AC current system, also to be understood within the context of the present invention as a two-phase AC current system, refers to any AC current system having several AC currents with the same frequency, which results in mutually constant, identical phase angles yielding a sum of 360°. 
         [0015]    (2) Description of Related Art 
         [0016]    A current supply arrangement of this type is disclosed in the document EP 2 388 236 A1, wherein in the current supply arrangement disclosed in this document n=3, m=2, p=6 and q=2. 
         [0017]    With such current supply arrangement for supplying power to a reactor for producing polysilicon according to Siemens process, electric energy can advantageously be supplied to the silicon rods, which are arranged inside the reactor and electrically connected to the current supply arrangement, both from the first current supply devices as well as from the second current supply device. 
         [0018]    Because the first current supply devices for supplying power to the silicon rods are designed for high currents at low voltages and the second current supply device for supplying the silicon rods is designed for low currents at high voltages, the suitable current supply devices for supplying power to the silicon rods can be selected commensurate with the state of the silicon rods. 
         [0019]    In a first phase at the beginning of a deposition process, when the silicon rods are present in form of so-called thin rods and have a very high ohmic resistance, the silicon rods are advantageously connected to the second current supply device, until the current flowing through the silicon rods produced by the high voltage has heated the silicon rods to a point where the ohmic resistance suddenly drops, which is also referred to as ignition of the silicon rods. When this state is reached, the silicon rods have a smaller resistance so that in the second phase following the first phase, the first current supply devices with high currents at low voltages can be used for supplying power to the silicon rods. The voltage can advantageously be adjusted by voltage sequence control such that the power converted in the silicon rods during the deposition process remains approximately constant. 
         [0020]    Because the second power supply device is used only during the first phase until ignition, and the second phase is significantly longer than the first phase, a second current supply device to which sequentially the different loads or groups of loads can be connected is advantageously employed, as described in EP 2 388 236 A1. The silicon rods are thus not ignited simultaneously, but rather sequentially. 
         [0021]    The loads are hereby connected to the second current supply device by way of the aforementioned switching means assembly, which makes it possible to connect the output of the second current supply device sequentially with the outputs of the switching means assembly, to which the loads, i.e. the silicon rods, are connected. 
         [0022]    In this way, a second current supply device could be used for several groups of loads, wherein each group is connected to a first current supply device. A second current supply device is therefore not required for each group of loads. 
         [0023]    In this way, in particular also the complexity of several medium voltage transformers could be reduced to a single medium voltage transformer which provides a sufficiently high voltage for the second current supply device. 
       BRIEF SUMMARY OF THE INVENTION 
       [0024]    It is the object of the invention to further reduce the complexity for the second current supply device. 
         [0025]    This object is attained according to the invention in that each terminal of the input of the at least one second current supply device is connected to a first tap of a secondary winding of one of the transformers, and that the taps for a reference potential of the secondary windings of the transformers, to which the terminals of the input of the at least one second current supply device are connected, can be connected with one another by way of controllable switching means. 
         [0026]    According to the improvement attained with the invention, the components installed for the first current supply device can now also be used for the second current supply device. In this way, components previously required for the connection of the second current supply device to a power grid can be eliminated or at least reduced in size. For example, in particular the first transformers or portions of the first transformers can also be used for supplying electric energy to the second current supply devices. While previously a medium voltage transformer was required for the second current supply device, this transformer can now be eliminated or replaced by a smaller transformer. 
         [0027]    The first transformers may be connected on the primary side in form of a polygon and connected to a multi-phase AC current grid with n phases. 
         [0028]    Primary windings of the first transformers, to the secondary windings of which the terminals of the input of the at least one second current supply device are connected, are preferably located in different paths of the polygon. In this way, uniform loading of the supply grid can be achieved. 
         [0029]    The first transformers made have one or more than one secondary winding. 
         [0030]    The secondary windings of the first transformers, to which the terminals of the input of the at least one second current supply device are connected, may be different secondary windings than the secondary windings connected to the first current supply device. Dedicated secondary windings, which are not used for supplying power to the first current supply devices, would then be provided for supplying power to the second current supply device. The primary windings of the first transformers are then commonly used for supplying power to the first current supply devices and the at least one second current supply device. 
         [0031]    Alternatively, first current supply devices may be connected to the secondary windings of the first transformers, to which the terminals of the input of the at least one second current supply device are connected. Both the primary windings and the secondary windings of the first transformers may then be commonly used for supplying power to the first current supply devices and the at least one second power supply device. 
         [0032]    First power supply devices may be connected to all secondary windings of the first transformers. 
         [0033]    The at least one converter group may include at least one or several second transformers. The converter group may include two second transformers, each having a secondary winding. Single-phase AC voltages with opposite phases may be present at the secondary winding of the two transformers, producing a common two-phase AC voltage at the two secondary windings. 
         [0034]    Alternatively, the second transformers may be m-phase transformers, producing an m-phase AC voltage at their secondary windings. 
         [0035]    The at least one converter group may include at least one or several converters, in particular frequency converters. The n-phase voltage at the input of the second current supply device may be converted into a single-phase or an m-phase voltage with the converters of a converter group. 
         [0036]    The current supply arrangement may include a controller for controlling the power controllers in voltage sequence control. 
         [0037]    The current supply arrangement may include a controller for controlling the switching means of the first switching groups. 
         [0038]    The current supply arrangement may also include a controller for controlling the switching means of the second switching group. 
         [0039]    The controllers for controlling the switching means of the first switching groups and the switching means of the second switching group may be coupled with one another or combined in a controller such that the switching means of the second switching group are closed only when the switching means of the first switching group are controlled to be closed. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0040]    Additional features of the present invention will be described in an example of a current supply arrangement according to the invention with reference to the appended circuit diagrams. It is shown in: 
           [0041]      FIG. 1  a circuit diagram of first transformers and their circuit, 
           [0042]      FIG. 2  a circuit diagram of a first power supply device in a first variant, a first switching group in a first variant, and loads connected thereto, 
           [0043]      FIG. 3  a circuit diagram of a first current supply device in a second variant, a first switching group in the first variant, and loads connected thereto, 
           [0044]      FIG. 4  a circuit diagram of a first power supply device in a third variant, a first switching group in a second variant and loads connected thereto 
           [0045]      FIG. 5  a circuit diagram of a second current supply device, and 
           [0046]      FIG. 6  the circuit diagram of a second switching group. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0047]    The current supply arrangement according to the invention and described with reference to the Figures includes n=3 first transformers (T 1 ), p=6 first current supply devices  1 , a second current supply device  2 , p=6 first switching groups  3  and a second switching group  4 . 
         [0048]    The primary windings  1 U,  1 V,  1 W of the first transformers T 1  are connected in a Delta configuration, wherein the corners of the triangle are connected via load switches to the three-phase conductors L 1 , L 2 , L 3  of a three-phase power grid. The load switches are normally-open switches. The corners of the triangle are also connected to ground via normally-closed switches. The normally-open switches and the normally-closed switches are operated simultaneously by a common drive. 
         [0049]    The first transformers T 1  have each two secondary windings  2 U,  3 U,  2 V,  3 V,  2 W,  3 W. Each secondary winding  2 U,  3 U,  2 V,  3 V,  2 W,  3 W has six taps  2 U 1  to  2 U 5 ,  2 UN,  3 U 1  to  3 U 5 ,  3 UN,  2 V 1  to  2 V 5 ,  2 VN,  3 V 1  to  3 V 5 ,  3 VN,  2 W 1  to  2 W 5 ,  2 WN,  3 W 1  to  3 W 5 ,  3 WN. A secondary-side reference potential is present at each tap  2 UN,  3 UN,  2 VN,  3 VN,  2 WN,  3 WN of each secondary winding  2 U,  3 U,  2 V,  3 V,  2 W,  3 W. Voltages for the reference potential with respect to the taps  2 UN,  3 UN,  2 VN,  3 VN,  2 WN,  3 WN can be tapped at the remaining five taps  2 U 1  to  2 U 5 ,  3 U 1  to  3 U 5 ,  2 V 1  to  2 V 5 ,  3 V 1  to  3 V 5 ,  2 W 1  to  2 W 5 ,  3 W 1  to  3 W 5 , hereinafter also referred to as first taps. 
         [0050]    The taps  2 UN,  3 UN,  2 VN,  3 VN,  2 WN,  3 WN for the reference potential are connected via a ground fault detectors with ground potential. 
         [0051]    The first current supply devices  1  illustrated in  FIGS. 2 ,  3  and  4  are constructed similarly. They are used, on one hand, for supplying power to the connected loads in a series connection. Accordingly, the first current supply devices have identical construction. The loads can also be arranged in groups using the first current supply devices according to  FIGS. 2 and 3  and the groups of loads formed by this grouping can be connected in parallel and supplied with electric energy. The first current supply devices according to  FIGS. 2 ,  3  and  4  are different in the following manner: 
         [0052]    Whereas the current supply devices according to  FIG. 2  are designed to supply electric energy to three groups of to loads each connected in series as well as in parallel, the current supply devices illustrated in  FIG. 3  are designed to supply electric energy to two groups with three loads each corrected in series as well as in parallel. This third variant of the first current supply device according to  FIG. 4  is designed to only supply electric energy to three loads connected in series. 
         [0053]    Each first current supply device  1  has terminals  131 ,  132 ,  133 ,  134 ,  135  which are connected with the first taps  2 U 1  to  2 U 5 ,  3 U 1  to  3 U 5 ,  2 V 1  to  2 V 5 ,  3 V 1  to  3 V 5 ,  2 W 1  to  2 W 5 ,  3 W 1  to  3 W 5  of a secondary winding  2 U,  3 U,  2 V,  3 V,  2 W,  3 W of a first transformer T 1 . The terminals  131 ,  132 ,  133 ,  134 ,  135  are connected inside the first current supply device with a node  12  via power controllers  11 . This node  12  together with the tap  2 UN,  3 UN,  2 VN,  3 VN,  2 WN,  3 WN for the reference potential of the secondary winding  2 U,  3 U,  2 V,  3 V,  2 W,  3 W, with which the terminals  131 ,  132 ,  133 ,  134 ,  135  are connected, forms an output of the first current supply device  1 . Serially connected loads are connected to this output of the first current supply device  1 . 
         [0054]    For switching between a parallel connection and a series connection of the loads, the first current supply devices have in the first variant ( FIG. 2 ) and in the second variant ( FIG. 3 ) a different wiring pattern and different switching means, which are illustrated in  FIG. 2  and in  FIG. 3 , but will not be further described here, because they were already described in detail in previously published documents. 
         [0055]    The series connections formed of the loads L 1  to L 6  ( FIG. 2  and  FIGS. 3 ) and L 1  to L 3  ( FIG. 4 ) are, as already described, connected to the output of one of the first current supply devices. Each individual load L 1  to L 6  and L 1  to L 3 , respectively, is also connected to a first switching group  3 . 
         [0056]    The first switching groups  3  have in the first variant ( FIG. 2  and  FIG. 3 ) an output  31  with q*m+1, i.e. when m=2 and q=3, seven terminals  311 ,  312 ,  313 ,  314 ,  315 ,  316 ,  317 . The loads L 1  to L 6  are connected to these terminals  311 ,  312 ,  313 ,  314 ,  315 ,  316 ,  317 . Each load is connected with two of the terminals  311 ,  312 ,  313 ,  314 ,  315 ,  316 ,  317 , supplying current to the load from the second current supply device. 
         [0057]    The first switching groups  3  have each a group  31  of at most q*m+1 controllable switching means. In the first variant of the first switching group, the first switching groups have seven controllable switching means  321 ,  322 ,  323 ,  324 ,  325 ,  326 ,  327 . The switching means  321 ,  322 ,  323 ,  324 ,  325 ,  326 ,  327  of a group  32  connect in a closed state the terminals  311 ,  312 ,  313 ,  314 ,  315 ,  316 ,  317  of the output  31  with the terminals  24 ,  25 ,  26 ,  27 ,  28 ,  29 ,  2 A of the output of the second current supply device  2 . 
         [0058]    The first switching groups  3  in the second variant ( FIG. 4 ) are different from those in the first variant ( FIGS. 2 and 3 ) in that the output has not seven, but only four terminals  311 ,  312 ,  313 ,  314  and the group of the switching means has only four switching means  321 ,  322 ,  323 ,  324 . The three loads L 1  to L 3 , which also connected to the second current supply device  1  in the second variant, are connected to these four terminals  311 ,  312 ,  313 ,  314 . 
         [0059]    The controllable switching means  321 ,  322 ,  323 ,  324 ,  325 ,  326 ,  327  of both variants of first switching groups have control terminals which are connected to a controller (not illustrated) via a control input  33  of the first switching group  3 . 
         [0060]    The controller for controlling the first switching groups controls all first switching groups. It ensures that when electric energy should be supplied from the second current supply device, the switching means  321 ,  322 ,  323 ,  324 ,  325 ,  326 ,  327  of preferably a single first switching group  3  are closed. 
         [0061]    The second current supply device  2  has an input  20  with n=3 terminals  201 ,  202 ,  203 , wherein the terminal  201  is connected with the terminal  3 U 4 , the terminal  202  with the terminal  3 V 4 , and the third terminal  203  with a terminal  3 W 4 . The second current supply device  2  has q=3 converter groups  21 . These converter groups  21  are connected with the terminals  201 ,  202 ,  203 , i.e. the converter groups  21  receive a three-phase voltage from the secondary windings  3 U,  3 V and  3 W. The three-phase voltage is converted in the converter groups  21  into an m-phase voltage, with m=2. In other words, a two-phase voltage with a phase of 180° is present at the outputs of the three converter groups  21 . 
         [0062]    Each converter group  21  has two converters  211  connected in parallel at an input side, wherein the converters  211  are connected at an output side with the terminals  201 ,  202 ,  203  of the input  20  of the second current supply device  2 . The converters  211  convert the three-phase voltage into a single-phase AC voltage. The converter groups  21  also include two second transformers T 2 , which transform the single-phase AC voltage at the output of the converter  211  Primary windings of the two second transformers T 2  of a converter group  21  have the same winding sense, whereas the secondary windings of the two transformers T 2  have opposite winding sense. In this way, voltages with opposite phases are produced at the output of the two second transformers T 2 . 
         [0063]    Secondary-side terminals of the two second transformers T 2  are connected with one another at second nodes  22  such that the voltage drop across the secondary windings  2  of second transformers interconnected at the node  22  is zero. 
         [0064]    Two second transformers T 2  are connected only with a single other second transformer T 2 . Accordingly, these transformers T 2  are connected with only a single second node  22 , whereas one of the secondary terminals of each of these transformers T 2  is not connected with any node  22 . 
         [0065]    These terminals of the secondary sides of the second transformers T 2  that are not connected with a second node  22  as well as the second nodes are connected with the terminals  231 ,  232 ,  234 ,  235 ,  236 ,  237  of the output  23  of the second current supply device  2 , to which the first switching groups  3  are connected. 
         [0066]    The second switching group  4  ( FIG. 6 ) has three terminals  43 ,  44 ,  45  which are connected with the taps  3 UN,  3 VN,  3 WN. The second switching means group  4  furthermore has two controlled switching means  41 ,  42  configured to connect the terminals  43 ,  44 ,  45  with one another. In addition, a control input  46  is provided via which the switching means  41 ,  42  can be controlled by a controller (not illustrated). When the second current supply device  2  is to be used for supplying electric energy to the loads, the switching means  41 ,  42  must be controlled so as to be closed. The switching means then form a star point, enabling current to flow from the first transformers T 1  to the second current supply device  2 .