CONVERTER, ARRANGEMENT WITH A CONVERTER AND METHOD FOR ITS OPERATION

Description

[0001] The invention relates to converters, arrangements with converter(s) and methods for their operation.

[0002] The present invention relates, among other things, to a converter with a partial converter, which comprises: partial converter-specific three-phase supply connections for connection to an incoming three-phase electrical system, as well as partial converter-specific three-phase output connections that form a partial converter-specific three-phase output system, and a partial converter-specific star point connection for contacting a star point of the partial converter-specific three-phase output system. Converters with partial converters of the type described, and thus also the partial converters themselves, are generally known and are offered and sold, for example, by Siemens AG under the product name Sinamics Perfect Harmony GH 180.

[0003] WO 2013 / 120675 A2 discloses a modular multi-level converter in which at least one electrical consumer or electrical energy generator is connected to the capacitor of at least one submodule via an inverter with a downstream transformer.

[0004] EP 2 815 913 A1 discloses a charging system for electric vehicles in which series circuits of submodules are connected in parallel to enable AC-DC-AC conversion.

[0005] Another modular multi-level converter with connected energy storage devices is known from WO 2012 / 152619 A2.

[0006] The invention is based on the object of further improving a converter of the type described.

[0007] This object is achieved according to the invention by a converter having the features according to claim 1. Advantageous embodiments of the converter according to the invention are specified in subclaims.

[0008] According to the invention, the converter comprises at least one further partial converter which has partial converter-specific three-phase feed-in connections, partial converter-specific three-phase output connections which form a partial converter-specific three-phase output system, and a partial converter-specific star point connection for contacting a star point of the partial converter-specific three-phase output system, the partial converters are connected in parallel with regard to their partial converter-specific three-phase feed-in connections and the parallel-connected partial converter-specific three-phase feed-in connections form converter-specific three-phase feed-in connections for connection to one and the same supplying three-phase system, and the partial converters are connected in parallel with regard to their partial converter-specific three-phase output connections.

[0009] A significant advantage of the converter according to the invention is that, with suitable control of the converter or the partial converters at the star point connections, it can optionally generate a direct voltage or an alternating voltage of any frequency and output a corresponding direct or alternating current.

[0010] A further advantage of the converter according to the invention is that, with appropriate external wiring of the parallel-connected three-phase output connections of the partial converter, a three-phase current can also be output on the output side.

[0011] An additional advantage of the converter according to the invention is that the partial converters can operate without a common DC link voltage.

[0012] It is advantageous if one and the other partial converter each have a converter module for each partial converter's own three-phase feed-in connection.

[0013] Each of the converter modules preferably has a module-side three-phase feed-in connection, a module-side neutral conductor connection, a module-side three-phase output connection and a module-side star point connection.

[0014] The module-side neutral conductor connections of the converter modules are preferably connected to one another and preferably form a partial converter-specific neutral conductor connection of the respective partial converter.

[0015] The module-side star point connections of the converter modules are preferably connected to each other and form the sub-converter's own star point connection of the respective sub-converter.

[0016] The module-side three-phase feed-in connections preferably each form one of the sub-converter's own three-phase feed-in connections of the respective sub-converter.

[0017] The module-side three-phase output connections preferably each form one of the sub-converter's own three-phase output connections of the respective sub-converter.

[0018] It is also advantageous if the converter modules each have two or more submodules electrically connected in series, a transformer with a primary winding and one secondary winding per submodule.

[0019] The transformer can be used, among other things, to achieve galvanic isolation between the sub-converter's own three-phase connections and the sub-converter's own star-point connections. The sub-converter's own three-phase connections and the sub-converter's own three-phase output connections are also galvanically isolated from each other, allowing different reference potentials to be freely specified for both connection systems. A reference potential for the sub-converter's own three-phase output connections can be specified, for example, via one or both of the sub-converter's own star-point connections.

[0020] Each of the submodules is preferably individually connected on the input side to one of the secondary windings of the transformer.

[0021] One of the terminals of the primary winding of the transformer preferably forms a module-side three-phase feed-in connection and another terminal of the primary winding of the transformer preferably forms a module-side neutral conductor connection.

[0022] The submodules preferably each have a rectifier module connected to a secondary winding of the transformer assigned to the submodule, a capacitor module arranged downstream of the rectifier module and an inverter module arranged downstream of the capacitor module.

[0023] The electrical series connection of the submodules is preferably based on the cascaded connection of the AC voltage connections of the inverter modules.

[0024] The invention also relates to a converter arrangement with at least one converter as described above.

[0025] It is advantageous if, in the converter arrangement, the parallel-connected partial converter's own three-phase output connections form converter-specific three-phase output connections that are accessible from the outside (externally).

[0026] The primary side of a three-to-two single-phase transformer is preferably connected to the inverter's own three-phase output terminals.

[0027] It is also advantageous if - alternatively or additionally - the converter's own three-phase output connections are connected to the primary side of a transformer which is suitable for outputting two alternating voltages with a phase shift of 90 degrees on its secondary side.

[0028] An electrical storage device and / or an electrical consumer, in particular an electrical resistor, is preferably connected between the partial converter's own star point connection of one partial converter and the partial converter's own star point connection of the at least one further partial converter.

[0029] It is also advantageous if the converter arrangement comprises a generator, in particular an asynchronous machine, which provides at least two generator-side three-phase output systems, one of the generator-side three-phase output systems is connected to the converter's own three-phase feed-in connections and another generator-side three-phase output system is connected to the converter's own three-phase output connections.

[0030] In an alternative embodiment variant, which is also considered advantageous, it is provided that the parallel-connected partial converter-specific output three-phase connections form internal converter-specific output three-phase connections and each of the converter-specific feed-in three-phase connections is electrically connected to one of the internal converter-specific output three-phase connections.

[0031] The invention also relates to a method for operating a converter as described above. According to the invention, a three-phase current is fed into the converter via a three-phase current feed-in system connected to the converter's own three-phase current feed-in terminals, and submodules in the converter's subconverters are controlled in such a way that a three-phase output current is available at the parallel-connected three-phase output terminals of the subconverter and / or a direct voltage or a single-phase alternating voltage is generated between the subconverter's own star-point terminals.

[0032] The invention is explained in more detail below using exemplary embodiments; by way of example, FIG 1 shows an embodiment of a converter arrangement according to the invention with an embodiment of a converter according to the invention, FIG 2 shows the converter according to Figure 1in more detail, FIG 3 an embodiment of a partial converter, FIG 4 an embodiment of a converter module, FIG 5 an embodiment of a submodule, FIG 6 an embodiment of an inverter module, FIG 7 a further embodiment of an inverter module, FIG 8 an embodiment of a capacitor module, FIG 9 an embodiment of a rectifier module, FIG 10 a further embodiment of a converter arrangement according to the invention with an embodiment of a converter according to the invention, FIG 11 a third embodiment of a converter arrangement according to the invention with an embodiment of a converter according to the invention and FIG 12 a further embodiment of a converter according to the invention.

[0033] For the sake of clarity, the same reference symbols are always used in the figures for identical or comparable components.

[0034] The FIG 1shows an arrangement with an exemplary embodiment of a converter 2 according to the invention, which is connected to an electrical power supply network 1 via a transformer 6. The current through the converter 2 is measured by a current measuring device 3, and the connection voltage at the converter 2 is measured by a voltage measuring device 4. The measured values ​​are processed by a converter control unit 5, which monitors and controls the converter 2. For example, a single-phase load 7 and / or a three-phase load 8 can be connected to the converter 2. The converter 2 is preferably a multilevel converter.

[0035] The FIG 2 shows an embodiment of the converter 2 according to Figure 1in more detail. The converter 2 comprises a first sub-converter and a second sub-converter. The two sub-converters, which are designated in the figures by reference numeral 9, are preferably structurally identical and each comprise sub-converter-specific three-phase feed-in connections L1', L2', L3' for connection to an incoming three-phase electrical system, sub-converter-specific three-phase output connections A', B', C', which form a sub-converter-specific three-phase output system, and a sub-converter-specific star-point connection X or Y for contacting a star point of the sub-converter-specific three-phase output system.

[0036] The two sub-converters 9 are connected in parallel with respect to their sub-converter-specific three-phase supply connections L1', L2', L3'. The parallel-connected sub-converter-specific three-phase supply connections L1', L2', L3' form the converter's own three-phase supply connections L1, L2, L3 for connection to one and the same supplying three-phase system.

[0037] The partial converters 9 are also connected in parallel with respect to their partial converter-specific three-phase output connections A', B', C'. In the variant according to Figure 2 The partial converter's own three-phase output terminals A', B', C' form the converter's own three-phase output terminals A, B, C, which are routed to the outside and are accessible from the outside. The converter's own three-phase output terminals A, B, C according to the Figure 2 can therefore also be referred to as externally accessible, inverter-specific three-phase output connections A, B, C.

[0038] The partial converter's own star point connections X and Y allow, depending on the control of the partial converter 9 by the converter control unit 5 according to the Figure 1an output of a direct voltage or a single-phase alternating voltage. The frequency of the single-phase alternating voltage depends on the control of the converter 2 by the converter control unit 5 and can be adjusted externally within a wide range.

[0039] The same applies to the three-phase voltage output at the converter's own three-phase output terminals A, B, and C, the frequency of which also depends on the control of the converter by the converter control unit 5 and can therefore also be externally adjusted within a wide range. The frequency of the three-phase voltage can differ from the frequency of the single-phase alternating voltage at the starpoint terminals X and Y, as well as from the frequency of the three-phase supply voltage of the supplying three-phase system at the converter's own three-phase supply terminals L1, L2, and L3.

[0040] The FIG 3 shows an embodiment of the partial converter 9 according to Figure 2The sub-converter 9 has a converter module 10 for each sub-converter's own three-phase feed-in connection L1', L2', L3'. Each of the converter modules 10 comprises a module-side three-phase feed-in connection Lm, a module-side neutral conductor connection Nm, a module-side three-phase output connection Am, and a module-side star point connection Sm. The module-side neutral conductor connections Nm of the converter modules 10 are connected to one another and form a sub-converter-owned neutral conductor connection N of the sub-converter 9.

[0041] The module-side star point connections Sm of the converter modules 10 are connected to one another and form the partial converter's own star point connection X or Y of the partial converter 9. The module-side three-phase feed-in connections Lm each form one of the partial converter's own three-phase feed-in connections L1', L2', L3' of the partial converter 9. The module-side three-phase output connections Am each form one of the partial converter's own three-phase output connections A', B', C' of the partial converter 9.

[0042] The FIG 4 shows an embodiment of the converter module 10 according to FIG 3 The converter module 10 comprises two or more submodules 13 electrically connected in series, a transformer 17 with a primary winding 17a, and a secondary winding 17b for each submodule 13. Each of the submodules 13 is individually connected on the input side to one of the secondary windings 17b of the transformer 17.

[0043] One of the terminals of the primary winding 17a of the transformer 17 forms a module-side three-phase feed-in connection Lm and the other terminal of the primary winding 17a forms a module-side neutral conductor connection Nm.

[0044] Also connected in series with the submodules 13 are a coupling inductance 12 and a current measuring device 11, which measures the current i_conv through the converter module 10 and preferably transmits the current measurement value to the converter control unit 5 according to Figure 1.

[0045] The FIG 5 shows an embodiment of the submodule 13 according to FIG 4 .

[0046] The submodule 13 has a rectifier module 16, which is connected to a secondary winding 17b of the transformer 17 assigned to the submodule 13 and is fed by the secondary winding 17b; the terminals Lsm and Nsm of the submodule 13 serve this purpose.

[0047] The submodule 13 also has a capacitor module 15 arranged downstream of the rectifier module 16 - viewed in the energy flow direction or energy supply direction E - and an inverter module 14 arranged downstream of the capacitor module 15 - viewed in the energy flow direction E. The FIG 4 The electrical series connection of the submodules 13 shown is based on the cascaded connection of the AC voltage connections AC1 and AC2 of the inverter modules 14. The internal connections of the rectifier module 16, the capacitor module 15 and the inverter module 14 are in the Figure 5 designated by the reference symbols DC7 and DC8 (for the rectifier module 16), DC3 and DC4 or DC5 and DC6 (for the capacitor module 15) and DC1 and DC2 (for the inverter module 14).

[0048] The FIG 6 shows an embodiment of an inverter module 14 according to FIG 5The inverter module 14 is formed by an H-bridge module consisting of four semiconductor switches 18. Suitable semiconductor switches 18 are, for example, IGBTs, IGCTs, IEGTs, or MOSFETs.

[0049] The FIG 7 shows a further embodiment of an inverter module 14 according to FIG 5 . The inverter module 14 according to FIG 7 is formed by a half-bridge module consisting of two semiconductor switches 18. Suitable semiconductor switches 18 are, for example, IGBT, IGCT, IEGT, or MOSFET.

[0050] The FIG 8 shows an embodiment of the capacitor module 15 according to FIG 5 . The capacitor module 15 consists of a capacitor 20, which buffers an intermediate circuit voltage Uz, and a parallel-connected voltage measuring device 19, which measures the intermediate circuit voltage Uz and preferably transmits the voltage measurement value to the converter control unit 5 according to FIG 1 transmitted.

[0051] The FIG 9shows an embodiment of a rectifier module 16 according to FIG 5 The rectifier module 16 comprises four diodes 21 for rectifying a single-phase alternating voltage. Alternatively, a three-phase bridge rectifier can also be used.

[0052] The FIG 10 shows a further embodiment of an arrangement with the converter 2 according to FIG 2 The converter 2 is used to couple a double-feeding asynchronous machine 22 to an electrical power supply network 1.

[0053] The asynchronous machine 22 has a first three-phase winding connected to the converter's own three-phase input terminals L1, L2, L3 of the converter 2, and a second three-phase winding connected to the grid 1 together with (or in parallel with) the converter's own three-phase output terminals A, B, C of the converter 2. At the first three-phase winding, the asynchronous machine 22 preferably generates a three-phase voltage with a frequency of, for example, between 5 and 10 Hz; the second three-phase winding of the asynchronous machine 22 is supplied with the three-phase voltage of the supply grid with a frequency of, for example, 50 Hz.

[0054] The converter 2 is connected at its star point terminals X and Y to a resistor and / or an electrical storage device 23, which can be used to absorb and / or store generator energy and thus to support the electrical power supply network 1 in the event of network faults.

[0055] The FIG 11 shows a third embodiment of an arrangement with the converter 2 according to FIG 2 . Inverter 2 is supplied with power via its own three-phase supply terminals L1, L2, L3, to which a three-phase electrical network (not shown) is connected.

[0056] The converter 2 serves to supply, for example, an electric railway network and, for this purpose, is connected to a three-to-two single-phase transformer 24 via its converter-specific output three-phase terminals A, B, and C. The three-to-two single-phase transformer 24 is preferably a Scott or LeBlanc transformer.

[0057] The three-to-two single-phase transformer 24 has terminals U1 and Y1 on the output side for outputting a first alternating voltage and U2 and Y2 for outputting a second alternating voltage. The first and second alternating voltages preferably have the same frequency, for example, 16 2 / 3 Hz, but are preferably phase-shifted by 90 degrees from each other.

[0058] The converter 2 is connected at its star point terminals X and Y to a resistor and / or an electrical storage device 23, which can be used to absorb and / or store generator energy and thus to support the railway network side or the electrical railway network in the event of network faults.

[0059] The FIG 12 shows a further embodiment of a converter 2 according to the invention in more detail. The converter 2 according to FIG 12 comprises a first partial converter and a second partial converter and corresponds to the converter 2 according to the FIG 2with the difference that the parallel-connected partial converter's own three-phase output connections A', B', C' form internal converter's own three-phase output connections A, B, C, which are connected to the converter's own three-phase feed-in connections L1, L2, L3, i.e. the also parallel-connected partial converter's own three-phase feed-in connections L1', L2', L3'.

[0060] The converter's own three-phase supply connections L1, L2, L3 and the partial converter's own star point connections X, Y, which enable the output of a direct voltage or a single-phase alternating voltage, are accessible or connectable from the outside.

[0061] In summary, the invention relates to a converter with a partial converter, which has the following: partial converter-specific three-phase supply connections for connection to an incoming three-phase electrical system, as well as partial converter-specific three-phase output connections, which form a partial converter-specific three-phase output system, and a partial converter-specific star point connection for contacting a star point of the partial converter-specific three-phase output system. According to the invention, the converter comprises at least one further partial converter, which has partial converter-specific three-phase supply connections, partial converter-specific three-phase output connections, which form a partial converter-specific three-phase output system, and a partial converter-specific star point connection for contacting a star point of the partial converter-specific three-phase output system.the partial converters are connected in parallel with respect to their partial converter-specific three-phase feed-in connections, and the parallel-connected partial converter-specific three-phase feed-in connections form converter-specific three-phase feed-in connections for connection to one and the same supplying three-phase system, and the partial converters are connected in parallel with respect to their partial converter-specific three-phase output connections, wherein the partial converters each have one converter module per partial converter-specific three-phase feed-in connection, and the converter modules each have two or more submodules connected in series on the output side, a transformer.

[0062] The information related to the Figures 1 to 12The converters 2 described as examples can, depending on the wiring, enable the generation of a three-phase voltage and, in addition, the generation of a direct or alternating voltage from a three-phase network on the input side, with any desired output frequency in each case without a common electrical intermediate circuit.

[0063] Although the invention has been illustrated and described in detail by means of preferred embodiments, the invention is not limited by the disclosed examples and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention, which is defined by the following claims.

Claims

1. Converter (2) having a converter subunit (9), which has: - three-phase supply terminals (L1', L2', L3'), located at the converter subunit, for connection to an electrical three-phase supply system, and - converter subunit-located three-phase output terminals (A', B', C') that form a converter subunit-located three-phase output system, and - a converter subunit-located starpoint terminal (X) for making contact with a star point of the converter subunit-located three-phase output system, - wherein the converter (2) comprises at least one further converter subunit (9) that has converter subunit-located three-phase supply terminals (L1', L2', L3'), converter subunit-located three-phase output terminals (A', B', C') forming a converter subunit-located three-phase output system, and a converter subunit-located starpoint terminal (Y) for making contact with a star point of the converter subunit-located three-phase output system, and - the converter subunits (9) are connected in parallel with respect to their converter subunit-located three-phase output terminals (A', B', C'), wherein the converter subunits (9) are connected in parallel with respect to their the converter subunit-located three-phase supply terminals (L1', L2', L3'), and the parallel-connected converter subunit-located three-phase supply terminals (L1', L2', L3') form converter-located three-phase supply terminals (L1, L2, L3) for connection to one and the same three-phase supply system, - wherein the converter subunit (9) and the further converter subunit (9) each have a respective converter module (10) for each converter subunit-located three-phase supply terminal, - wherein each of the converter modules (10) has in each case a module-side three-phase supply terminal (Lm), a module-side neutral conductor terminal (Nm), a module-side three-phase output terminal (Am) and a module-side starpoint terminal (Sm), - wherein the converter modules (10) each have two or more submodules (13) that are connected electrically in series on the output side, a transformer (17) having a primary winding (17a), and, for each submodule (13), a respective secondary winding (17b), - wherein each of the submodules (13) is connected, on the input side, in each case individually to one of the secondary windings of the transformer, - wherein the primary windings (17a) of the respective transformers (17) of the converter subunit (9) and / or the further convert subunit (9) are arranged in a star connection and are each connected to the converter subunit-located three-phase supply terminals (L1', L2', L3') in such a manner that the neutral conductor terminals (Nm) of the converter modules (10) that are on the module side are connected to one another and form a converter subunit-located neutral conductor terminal (N) of the respective converter subunit (9) and the three-phase supply terminals (Lm) that are on the module side each form one of the converter subunit-located three-phase supply terminals (L1', L2', L3') of the respective converter subunit (9), - wherein the starpoint terminals (Sm) of the converter modules (10) that are on the module side are connected to one another and form the converter subunit-located starpoint terminal (X, Y) of the respective converter subunit (9), - wherein the three-phase output terminals (Am) that are on the module side each form one of the converter subunit-located three-phase output terminals (A', B', C') of the respective converter subunit (9).

2. Converter (2) according to claim 1, characterised in that the subunit-located starpoint terminals (X, Y) make it possible to output a DC voltage or a single-phase AC voltage.

3. The converter (2) according to one of the preceding claims, the two or more submodules (13) of the converter modules (10) that are connected electrically in series on the output side are arranged between the module-side three-phase output terminal (Am) and the module-side starpoint terminal (Sm).

4. Converter (2) according to one of claims 1 to 3, characterised in that - one of the terminals of the primary winding (17a) of the transformer (17) forms a three-phase supply terminal on the module side, and - another terminal of the primary winding (17a) of the transformer forms a neutral conductor terminal on the module side.

5. Converter (2) according to one of claims 1 to 4, characterised in that the submodules (13) each have a rectifier module (16), which is connected to a secondary winding of the transformer that is associated with the submodule (13), a capacitor module (15) that is downstream of the rectifier module (16), and an inverter module (14) that is downstream of the capacitor module (15).

6. Converter (2) according to one of preceding claims 1 to 5, characterised in that the connection of the submodules (13) electrically in series is based on the cascaded interconnection of the AC voltage terminals (AC1, AC2) of the inverter modules (14).

7. Converter arrangement, characterised in that it is equipped with at least one converter (2) according to one of the preceding claims.

8. Converter arrangement according to claim 7, characterised in that - the converter subunit-located three-phase output terminals (A', B', C') that are connected in parallel form converter-located three-phase output terminals (A, B, C), and - the primary side of a three-to-two single-phase transformer (24) is connected to the converter-located three-phase output terminals (A, B, C).

9. Converter arrangement according to one of preceding claims 7 to 8, characterised in that - the converter subunit-located three-phase output terminals (A', B', C') that are connected in parallel form converter-located three-phase output terminals (A, B, C), and - the converter-located three-phase output terminals (A, B, C) are connected to the primary side of a transformer (24) that is suitable for outputting two AC voltages with a phase offset of 90 degrees on its secondary side.

10. Converter arrangement according to one of preceding claims 7 to 9, characterised in that an electrical storage facility (23) is connected between the converter subunit-located starpoint terminal (X) of the one converter subunit (9) and the converter subunit-located starpoint terminal (Y) of the at least one further converter subunit (9).

11. Converter arrangement according to one of preceding claims 7 to 10, characterised in that an electrical consumer (23) is connected between the converter subunit-located starpoint terminal (X) of the one converter subunit (9) and the converter subunit-located starpoint terminal (Y) of the at least one further converter subunit (9).

12. Converter arrangement according to one of preceding claims 7 to 11, characterised in that - the converter arrangement comprises a generator, in particular an asynchronous machine (22) that provides at least two three-phase output systems on the generator side, - one of the three-phase output systems on the generator side is connected to the converter-located three-phase supply terminals (L1, L2, L3), and - another three-phase output system on the generator side is connected to the converter-located three-phase output terminals (A, B, C).

13. Converter arrangement according to one of preceding claims 7 to 12, characterised in that - the converter subunit-located three-phase output terminals (A', B', C') that are connected in parallel form internal converter-located three-phase output terminals (A, B, C), and - each of the converter-located three-phase supply terminals (L1, L2, L3) is electrically connected to a respective one of the internal converter-located three-phase output terminals (A, B, C).

14. Method for operating a converter (2) according to one of the preceding claims, characterised in that - using a three-phase supply system that is connected to the converter-located three-phase supply terminals (L1, L2, L3), a three-phase current is supplied to the converter (2), and - submodules (13) in the converter subunits (9) of the converter (2) are controlled such that an output three-phase current is provided at the converter subunit-located three-phase output terminals (A', B', C') that are connected in parallel and / or a DC voltage or single-phase AC voltage is generated between the converter subunit-located starpoint terminals (X, Y).