Abstract:
A power supply arrangement for producing polysilicon with a central control unit and a basic supply unit, which are regulated and controlled by control means. The basic supply unit supplies the supply module with electric energy, an output for connecting to loads which are supplied with electric energy from the mains via basic supply unit, and controllable switches, which are connected to the input and to the output and which are configured for adjusting the energy to be supplied to the loads. The switches are controllable. The control unit is supplied with electric energy. The power supply includes a communication bus. The control module and the basic supply module are connectable to the control module and the basic supply module to the communication bus. The control module and the basic supply module provide connections to the control module and the basic supply module to the communication bus.

Description:
BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The present invention relates to a power supply arrangement, in particular for reactors for producing polysilicon, with a control unit and at least one basic supply unit, wherein the control unit comprises at least one control and regulating means for controlling and/or regulating the basic supply unit, the basic supply unit comprises, at least one input for connection to a power mains for supplying electric energy, at least one output for connecting with a group of loads which can be supplied via the basic supply unit with electric energy from the power mains, and controllable switches, preferably thyristors, which are connected at least indirectly with the input and at least indirectly with the output and which are configured for adjusting the energy to be supplied to the loads via the output, wherein the switches can be controlled by the control unit. 
     (2) Description of Related Art 
     A power supply arrangement of this type is known, for example, from the document DE 20 2004 014 812 U1. The utility model discloses a power supply arrangement with a basic supply unit which can be used to supply an electric voltage to loads connected in series to the power supply arrangement. A portion of the loads can be supplied in parallel with a medium voltage from a medium voltage supply unit. The control unit is not described in detail in this document. In particular, it is not disclosed how the control unit acts on the controllable switches of the basic supply unit or the medium voltage supply unit. 
     DE 20 2009 003 325 U1 also describes a power supply arrangement with a basic supply unit and a medium voltage supply unit, wherein the basic supply unit is not described in detail. A control unit is also mentioned in the document, but not described in detail. 
     Another disadvantage of this type of power supply arrangement as well as of other power supply arrangements is that they are built individually and to order. Each power supply is hence an individual solution for a particular power supply problem, although experiences from prior solutions can be relied upon. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of the invention to improve a power supply arrangement of the aforedescribed type such that starting with a simple power supply arrangement with a control unit and a basic supply unit, the power supply arrangements can be flexibly adapted without requiring a new design for a particular solution. 
     This object is attained by the invention in that the control unit is a control module and the basic supply unit is a basic supply module, that the control module has an input for connection to the power mains for supplying the control module with electric energy, that the power supply arrangement includes a communication bus, and that both the control module and the basic supply module include an interface configured for connecting the control module and the basic supply module to the communication bus. 
     A modular power supply arrangement according to the invention can be flexibly expanded from an arrangement with a control module and a basic supply module. These expansions may include, for example, additional basic supply modules which may optionally be added later to form a power supply arrangement. The modules to be added are connected to the control module via interfaces and the communication bus to enable control or regulation by the control module. In addition, the modules have dedicated inputs for connection to the power mains. The power supply arrangement of the invention is therefore easily scalable. Accordingly, the power supply arrangement according to the invention can be adapted to the practical application of producing polysilicon with the Siemens process by, for example, matching the number of basic supply modules to the number of the thin silicon rods to be supplied with power. Optionally, modules can be also be added later to a power supply arrangement for supplying power to a polysilicon reactor operating according to Siemens process to improve process control. A manufacturer of current supply arrangements or a polysilicon manufacturer can thereby flexibly adapt a facility with Siemens reactors to changing conditions, for example prices for raw material, energy or polysilicon, or changing demand. 
     The power supply arrangement may include a transformer with several secondary-side taps, wherein each tap of the transformer may be associated with one input. A group of the controllable switches may be associated with each input of the basic supply module for adjusting via this tap the electric energy to be withdrawn from the power mains. The controllable switches may be, for example, thyristors. The groups of the controllable switches may advantageously be connected without the interconnection of additional switches with, on one hand, the taps and, on the other hand, with the output of the basic supply module. Advantageously, in addition to the controllable switches of the aforementioned group, no additional switch, in particular no mechanical high-current switch for safe disconnection, such as a contactor, are disposed in the current path between the tap and the output. 
     However, a node may be provided between the groups of the controllable switches and the output. The node may be connected to a reference potential via an additional controllable switch. In this way, the output of the basic supply module can be grounded and short-circuited via ground. This may be desirable if the loads connected to the output of a basic supply module are supplied with electric energy in other ways. Preferably, a basic supply module according to the invention has an interlock which ensures that either a controllable switch of one of the groups of the controllable switches or the additional controllable switch are closed for connection to the reference potential. In this way, simultaneous supply of electric energy from the basic supply module and from other sources to the loads connected to the output of the basic supply module can be prevented. 
     At the output of a basic supply module, loads can be supplied with AC voltages of 0 V to 3000 V, preferably to 2500 V, and with AC currents of 0 A to 5000 A, preferably to 4000 A, in particular to 3000 A. A three-phase AC voltage in the medium voltage range of, for example, 6000 V to 33,000 V can be applied to the input of the transformer. A single-phase AC voltage of 0 to 3000 V, preferably of 2500 V, may be present at the input of the basic supply module. 
     The basic supply module may include means for identifying a ground fault. 
     The modular power supply arrangement according to the invention may include several identical or similar basic supply modules. 
     A modular power supply arrangement of the invention may include as a module of the different type a medium voltage supply module having at least one input for connection to a power mains or to the transformer for supplying electric energy, and outputs for connection to a corresponding load from the group of loads adapted to be supplied from the power mains with electric energy, and an interface, by which the power supply arrangement can be connected to the communication bus. 
     While the basic supply module supplies at the output of the power supply arrangement configured to supply power to the connected loads preferably a voltage of 0 V to 2000 V, preferably up to 2500 V, still higher voltages can be provided with a medium voltage supply module. For example, AC voltages of 0 V to 12,000 V, in particular to 8000 V, and AC currents of 0 A to 50 A, preferably to 20 A, may be provided at the outputs of the medium voltage supply module. 
     A medium voltage supply module of a power supply arrangement according to the invention can be supplied at its input with a three-phase AC voltage of 400 V from the power mains or a tap of a transformer. The medium voltage supply module may include at least one converter for increasing a voltage supplied at the input. A corresponding converter may be associated with each output of the medium voltage supply module. 
     The linked voltage across the outputs may be equal to 0 V at least during the time when the loads connected to the output of the medium voltage supply module are supplied with electric power. Two corresponding terminals may be associated with the outputs of the medium voltage supply module, wherein with the exception of two outer terminals all other inner terminals are associated with two outputs. The outer terminals of the medium voltage supply module are each connected with a respective terminal of the output of the basic supply module. The loads can then be concurrently connected in series to the output of a basic supply module, without allowing current flow from the medium voltage supply module to the output of the basic supply module. 
     The modular power supply arrangement may include several identical or similar medium voltage supply modules. 
     Similar in the context of the specification means that although the medium voltage modules may be different, at least the interfaces to the communication bus are identical and each medium voltage supply module has a dedicated connection to the grid. 
     Preferably, the number of medium voltage supply modules corresponds to the number of basic supply modules. The medium voltage supply modules and the basic supply modules may each be associated in pairs to a corresponding group of loads. 
     The modular power supply arrangement of the invention may include a medium frequency supply module which has at least one input for connection with a power mains or the transformer for supplying electric energy and outputs for connection to a corresponding load from the group of loads adapted to be supplied with electric energy from the power mains, and which includes an interface for connecting the power supply arrangement to the communication bus. 
     AC voltages of 0 V to 100 V, preferably 50 V, and AC currents of 0 A to 1500 A at with frequency of 2 kHz to 250 kHz, preferably from 20 kHz to 150 kHz, can be provided at the outputs of the medium frequency supply module. 
     The medium frequency supply module of a modular power supply arrangement may include one or several frequency converters for changing, in particular increasing, the frequency of a voltage from the power mains and supplied at the input. 
     A corresponding output of the medium frequency supply module may be associated with each output of one of the frequency converters. The linked voltage across a pair of outputs of the medium frequency supply modules may be equal to 0 V at least when the loads connected to the output of the medium frequency supply module are supplied with power. 
     Two respective terminals may be associated with the outputs of the medium frequency supply module, with each pair of outputs having two outer terminals and one inner terminal, wherein the outer terminals are associated with a corresponding one of the two outputs of the pair of outputs and the inner terminal is associated with two outputs of the pair of outputs. 
     A three-phase AC voltage of 200 V to 690 V, preferably of 400 V, can be supplied at the input of the medium frequency supply module between the two outer conductors from a power mains or from the transformer. 
     The modular power supply arrangement may include several identical or similar medium frequency supply modules. For connection to the communication bus, the similar medium frequency supply modules have at least interfaces that are identical to those of the other medium frequency supply modules, as well as mains connections. The number of the medium frequency supply modules may correspond to the number of the basic supply modules. 
     Advantageously, in a modular power supply arrangement according to the invention, the control module, basic supply module and optionally each medium frequency supply module are each arranged in a corresponding control cabinet. Each medium voltage supply module may be arranged in a control cabinet together with a basic supply module. Each control cabinet advantageously has a mains connection. Each module may have a connection to an auxiliary power supply. Each control cabinet may include a display unit, in particular a display screen. 
     Each module, with the exception of the control module, may have a decentralized control unit which is connected inside the module with, for example, recorders for measured variables, control terminals of controllable switching elements, for example thyristors and the like. The decentralized control units may be connected to the communication bus via the interfaces of the modules. The decentralized control units may be arranged downstream of the control module. 
     The power supply arrangement according to the invention is preferably suitable and configured to supply energy to an even number of loads and has therefore an even number of outputs. 
     An exemplary embodiment of a modular power supply arrangement according to the invention will now be described with reference to the figures. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         FIG. 1   a, b  shows a schematic circuit diagram of the modular power supply arrangement according to the invention, and 
         FIG. 2  shows a schematic circuit diagram of a modular power supply arrangement with three basic supply modules. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows the wiring connections of the modular power supply arrangement according to the invention, as well as a transformer  40 , a basic supply module B, a medium voltage supply module MV and a medium frequency supply module MF. A control module and a communication bus are not illustrated. Also not illustrated are the control lines, the measured value recorder and the measured value lines located inside the basic supply module B, the medium voltage supply module MV and the medium frequency supply module MF, and the interfaces and interface driver circuits of the modules B, MV MF to the communication bus. Likewise, optional control units and/or driver or trigger circuits optionally arranged downstream of the control module and disposed in the basic supply module B, the medium voltage supply module MV and the medium frequency supply module MF are also not shown. 
     The basic supply module B of the modular power supply arrangement according to  FIG. 1  includes a mains connection connected to a primary side of a transformer  40 . The secondary side of the transformer  40  includes a plurality of first taps  401  to  406 . Each of the first taps  401  to  406  is connected in the basic supply module B via two anti-parallel connected thyristors  11  or a triac with a node  12 . The node  12  is connected, on one hand, to a first terminal  131  of the output of the basic supply module B. The node  12  can also be connected to ground via a controllable switch  141 . The second tap  407  of the secondary side of the transformer  40  is connected to a terminal  132  of the output of the basic supply module B and can also be connected to ground via a controllable switch  142 . 
     The largest possible voltage drop occurs between the first tap  401  and the second tap  407  of the secondary side of the transformer  40 . Because the other first taps  402  to  406  are located between these two taps  401  and  407 , the voltage drop between one of these first taps  402  to  406  and the second tap  407  is smaller than the largest possible voltage. Depending on which of the thyristor branches  111  to  116  is conducting, a higher or lower voltage is provided at the node  12  and hence at the terminal  131 , provided that the switch  141  is open. The voltage between the highest possible voltage between the first tap  401  and the second tap  407  and the smallest voltage between the first tap  406  and the second tap  407  can be continuously adjusted by adjusting the firing angle of the thyristors or the phase angle. 
     A basic supply module B ensures supply of regulated or base load power to the silicon rods or thin silicon rods R 1  to R 4  which are connected in series to the basic supply module B between the terminals  131  and  132 . 
     The output power of a Siemens reactor can be improved with the medium voltage supply module MV and the medium frequency supply module MF. Accordingly, the medium voltage supply module MV and the medium frequency supply module MF may be provided additionally in the modular switching arrangements. 
     The silicon rods or thin silicon rods R 1  to R 4  supplied with current from the basic supply module B are insulators at low temperatures, i.e., even at room temperature. The silicon rods or thin silicon rods R 1  to R 4  become conducting only through heating. The medium voltage supply module MV can be used to heat the silicon rods or thin silicon rods R 1  to R 4  at the beginning of the deposition process, so that they become conducting and can be supplied with current from the basic supply module B (dielectric heating). For this purpose, the outputs of the medium voltage supply module B supply higher voltages than the basic supply module B. A respective one of the silicon rods or thin silicon rods R 1 , R 2 , R 3 , R 4  is connected at each of the outputs. Preferably, the medium voltage provided at the outputs has also a higher frequency of, for example, 5 kHz, than the mains frequency. 
     The medium voltage supply module MV shown in  FIG. 1   a  has a total of four converters  20  which can be used to generate from a three-phase mains voltage a voltage with higher frequency. This voltage is then upconverted by the transformers  21  to a higher voltage of, for example, up to 12 kV. This medium voltage which has a higher frequency than the mains voltage is then supplied at the outputs of the medium voltage supply module MV. A respective one of the silicon rods or thin silicon rods R 1 , R 2 , R 3 , R 4  is connected at each of the outputs. 
     The outputs  23  of the medium voltage supply module MV are linked with one another. For this reason, only five terminals  231  to  235  are provided for the illustrated four outputs. Of these five terminals, the terminals  232 ,  233  and  234  are used for two respective consecutive outputs of the chain, whereas the terminals  231  and  235  are used for one output located at the beginning and an end of the chain of outputs. 
     The voltages at the outputs of the medium voltage supply module MV are set so that the voltage drop across the entire chain of the outputs  23  is equal to 0 V. Accordingly, there is no voltage drop between the terminals  231  and  235  during operation of the medium voltage supply module MV. Because these terminals  231  and  235  are also located at the end of the series connection of the silicon rods or thin silicon rods R 1  to R 4  and because this series connection is connected to the output of a basic supply module B, there is no voltage present at the output of the basic supply module B which is generated by the medium voltage supply module MV during the operation of the medium voltage supply module MV. 
     Unlike the medium voltage supply module MV, the medium frequency supply module MF is used to supply a current to the silicon rods or thin silicon rods R 1 , R 2 , R 3 , R 4  simultaneously with the basic supply module B. The medium frequency supply module MF provides at its outputs  34  a voltage with a higher frequency than the mains voltage or the output voltage of the basic supply module B. 
     The medium frequency supply module MF has two three-phase mains connections. Each of these mains connections is connected inside the medium frequency supply module MF to a corresponding frequency converter. Each frequency converter has two stages  31 ,  32 . The first stages  31  convert the mains voltages to a corresponding DC voltage. The DC voltages are converted in the second stages  32  of the frequency converter to the higher-frequency AC voltages. These high-frequency AC voltages are supplied to the primary sides  331  of corresponding transformers  33 . The magnetic flux in each of the transformers  33  passes on the secondary side through two coils  332 . The secondary coils  332  of each of the two transformers  33  are identical. Each secondary coil  332  is connected in parallel with an output  34  of the medium frequency supply module MF. A respective one of the silicon rods or thin silicon rods R 1 , R 2 , R 3 , R 4  is connected to each of the outputs  34 . Each of two respective outputs  34  at linked with one another. These are the outputs  34  which receive a voltage from the same transformer  33 , meaning that two taps of the secondary coil  332  are each connected with a respective terminal  341 ,  343 , and  344 ,  346 . The other two taps of the secondary coil  332  are each connected with a respective node  351  and  352 . The nodes  351  and  352  are connected to the terminals  343  and  345 . The secondary coil  332  of each transformer  32  can also be replaced by a secondary-side coil with a center tap located exactly at the center of the secondary coil of the transformer. 
     The magnitude of the voltage drops across the secondary coils  332  of each transformer  32  is identical. However, the voltages have the opposite polarity, because the winding sense of the two secondary coils  332  of each transformer  32  is reversed. Linking the outputs  34  associated with one transformer  32  results in a zero voltage drop between the terminals  341 ,  343 , and  344 ,  346 , respectively. Because the terminals  343 ,  344  are connected to each other at least via an electrically conducting connection between the silicon rods or thin silicon rods R 2  and R 3 , there is also no voltage drop between the terminals  341  and  346  of the outputs  34  of the medium frequency supply module MF. Accordingly, zero current is supplied from the medium frequency module MF to the basic supply module B during the parallel operation with the basic supply module B, although the terminals  341  and  346  are connected to the terminals  131  and  132 , respectively, of the basic supply module. 
     However, a current may still be supplied from the basic supply module B into the medium frequency supply module MF. This can be prevented by arranging between the coils on the secondary side of the transformers  32  and the terminals  341 ,  343 ,  344  and  346  a capacitor  36  which filters, i.e. blocks, the low-frequency current provided by the basic supply module. As a result, the medium frequency supply module MF is decoupled from the basic supply module B. 
     The three illustrated modules B, MV, MF are configured so that they can be operated independent from one another and that one module is not required for the other module. All modules have dedicated mains connections. 
     In addition to the mains connections for supplying power illustrated in the Figure, the auxiliary current supplies are separate from one another. The connections via the interface and a communication bus (not illustrated) to the unillustrated control module are also independent from one another.