WO2010136033A1 - Converter system for a wind turbine - Google Patents

Converter system for a wind turbine Download PDF

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Publication number
WO2010136033A1
WO2010136033A1 PCT/DK2010/000065 DK2010000065W WO2010136033A1 WO 2010136033 A1 WO2010136033 A1 WO 2010136033A1 DK 2010000065 W DK2010000065 W DK 2010000065W WO 2010136033 A1 WO2010136033 A1 WO 2010136033A1
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WO
WIPO (PCT)
Prior art keywords
filter
primary
converter
core
terminal
Prior art date
Application number
PCT/DK2010/000065
Other languages
French (fr)
Other versions
WO2010136033A8 (en
Inventor
Anshuman Tripathi
Gil Lampong Opina
Amit Kumar Gupta
Michael Casem Tumabcao
Original Assignee
Vestas Wind System A/S
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Vestas Wind System A/S filed Critical Vestas Wind System A/S
Publication of WO2010136033A1 publication Critical patent/WO2010136033A1/en
Publication of WO2010136033A8 publication Critical patent/WO2010136033A8/en

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F37/00—Fixed inductances not covered by group H01F17/00
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
    • H02M7/68—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters
    • H02M7/72—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/79—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/81—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal arranged for operation in parallel
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F30/00—Fixed transformers not covered by group H01F19/00
    • H01F30/06—Fixed transformers not covered by group H01F19/00 characterised by the structure
    • H01F30/12—Two-phase, three-phase or polyphase transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/28—The renewable source being wind energy
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0043—Converters switched with a phase shift, i.e. interleaved
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0067—Converter structures employing plural converter units, other than for parallel operation of the units on a single load
    • H02M1/008—Plural converter units for generating at two or more independent and non-parallel outputs, e.g. systems with plural point of load switching regulators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/493—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode the static converters being arranged for operation in parallel
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/76—Power conversion electric or electronic aspects

Definitions

  • the present invention relates to a converter system, in particular a converter system for a wind turbine.
  • a converter system comprising a filter device, a first converter having a first primary converter terminal and a first secondary converter terminal, and a second converter having a second primary converter terminal and a second secondary converter terminal.
  • the filter device has at least a first primary filter terminal, a second primary filter terminal, a first secondary filter terminal connected to the first primary converter terminal and a second secondary filter terminal connected to the second primary converter terminal, wherein a first primary filter coil is arranged between the first primary filter terminal and the first secondary filter terminal. Further, a second primary filter coil is arranged between the second primary filter terminal and the second secondary filter terminal, the first primary filter coil and the second primary filter coil being wound around a common core.
  • a wind turbine comprising a converter system and a generator connected to the first and second primary filter terminals of the converter system. Further, a wind turbine is provided, comprising a converter system wherein the first and second primary filter terminals are adapted for connection towards the grid.
  • a common or shared core enables reduced mutual inductance between the inductors/coils, thus leading to a smaller size of the converter system which is in particular advantageous in a wind turbine where components of relatively small size are desired.
  • Fig. 1 schematically illustrates a converter system
  • FIG. 2 schematically illustrates an exemplary filter device of the converter system in Fig. 1
  • Fig. 3 schematically illustrates a converter system
  • Fig. 4 schematically illustrates an exemplary filter device of the converter system in Fig. 3,
  • Fig. 5 schematically illustrates an application of the converter system for the generator side
  • Fig. 6 schematically illustrates an application of the converter system for the grid side
  • Fig. 7 schematically illustrates a converter system
  • Fig. 8 schematically illustrates an exemplary filter device of the converter system in Fig. 7,
  • Fig. 9 schematically illustrates inter-capacitance between windings/coils of a single core
  • Fig. 10 schematically illustrates an exemplary filter device of the converter system in Fig. 1 .
  • Fig. 11 schematically illustrates an exemplary common core.
  • the converter system increases the design flexibility due to the modular construction of the converter system.
  • the converter system comprises n converters, where n > 2
  • the converter system may comprise two converters or more, such as three, four, five, six, seven, eight or more converters.
  • each converter has primary converter terminal(s) connected to secondary filter terminals of the filter device.
  • the converter system comprises four converters having primary converter terminals connected to secondary filter terminals.
  • the filter device comprises at least one first primary terminal and at least one second primary terminal.
  • the converter system is configured for a three phase power system.
  • the filter device may comprise a set of first primary filter terminals comprising three first primary filter terminals, e.g. for connection to a three phase power grid or a three phase generator.
  • the filter device may comprise a set of second primary filter terminals comprising three second primary filter terminals, e.g. for connection to a three phase power grid or a three phase generator.
  • the filter device may comprise any suitable number of primary filter terminal sets corresponding to the number of converters in the converter system.
  • the filter device comprises at least one first secondary filter terminal and at least one second secondary filter terminal.
  • the secondary filter terminals of the filter device may be connected to primary converter terminals of a plurality of converters.
  • the filter device may comprise a set of first secondary filter terminals comprising three first secondary filter terminals, e.g. for connection to primary converter terminals of a first converter in a three phase converter system.
  • the filter device may comprise a set of second secondary filter terminals comprising three second secondary filter terminals, e.g. for connection to primary converter terminals of a second converter in a three phase converter system.
  • the filter device may comprise any suitable number of secondary filter terminal sets corresponding to the number of converters in the converter system, e.g. two, three, four five, six, seven, eight or more secondary filter terminal sets.
  • the filter device comprises a suitable number of filter coils.
  • the filter device may comprise a first primary filter coil arranged between a first primary filter terminal and a first secondary filter terminal, and a second primary filter coil arranged between a second primary filter terminal and a second secondary filter terminal.
  • the first primary filter coil and the second primary filter coil are wound around a common core.
  • the filter device may comprise a first secondary filter coil arranged between a first primary filter terminal and a first secondary filter terminal, and a second secondary filter coil arranged between a second primary filter terminal and a second secondary filter terminal.
  • the first secondary filter coil and the second secondary filter coil are wound around a common core.
  • the filter device may comprise a first tertiary filter coil arranged between a first primary filter terminal and a first secondary filter terminal, and a second tertiary filter coil arranged between a second primary filter terminal and a second secondary filter terminal.
  • the first tertiary filter coil and the second tertiary filter coil are wound around a common core.
  • the first primary filter coil and the first secondary filter coil are wound around a common core.
  • the first primary filter coil and the first tertiary filter coil are wound around a common core.
  • the common core may comprise a first core bridge, and a first primary core leg, an optional first secondary core leg and an optional first tertiary core leg, the first core leg(s) extending from the first core bridge.
  • the common core may comprise an end core bridge.
  • the common core may comprise a second core bridge, and a second primary core leg, an optional second secondary core leg and an optional second tertiary core leg, the second core leg(s) extending from the second core bridge.
  • the common core may comprise a number of E-shaped core elements, each core element comprising a core bridge, and a primary core leg, a secondary core leg and a tertiary core leg extending from the core bridge.
  • the number of E-shaped core elements may correspond to the number of converters in the converter system.
  • the common core may comprise a number of U-shaped core elements, each core element comprising a core bridge, and a primary core leg and a tertiary core leg extending from the core bridge.
  • the number of U-shaped core elements may correspond to the number of converters in the converter system.
  • a common core may combine a number of E-shaped core elements and a number of U-shaped core elements.
  • the filter coils of the filter device may be wound around core legs and/or core bridges of the common core in any suitable configuration in order to obtain desired flux flow in the common core.
  • the distal ends of the core legs of a core element may contact or abut the core bridge of another core element.
  • An air gap may be provided between the distal end of a core leg and a core bridge.
  • One or more air gaps may be distributed along the length of a core leg to minimize localized heating due to the high reluctance of a single air gap area.
  • An air gap size may range from 0.1 mm to about 100 mm, e.g. in the range from about 1 mm to about 50 mm, depending on the electrical requirements of the filter device design.
  • a primary filter coil may be wound around the primary core leg of a core element, e.g. the first primary filter coil may be wound around the first primary core leg or the second primary filter coil may be wound around the second primary core leg or both.
  • a secondary filter coil may be wound around the secondary core leg or the core bridge of a core element.
  • the first secondary filter coil may be wound around the first secondary core leg or around the first core bridge
  • the second secondary filter coil may be wound around the second secondary core leg or around the second core bridge.
  • a tertiary filter coil may be wound around the tertiary core leg of a core element.
  • the first tertiary filter coil may be wound around the first tertiary core leg or the second tertiary filter coil may be wound around the second tertiary core leg or both.
  • One or more filter coils may be wound around an end core bridge.
  • One or more filter coils may be wound around the same core leg or core bridge.
  • the common core may comprise one or more spacing elements. Spacing element(s) may be inserted in air gap(s) between core elements or constitute a part of a core leg and/or a core bridge. Spacing element(s) may be inserted between the distal end of core legs and an adjacent core bridge.
  • the spacing element(s) may be made of material having low permeability, such as a high temperature Nomex paper or high temperature laminates.
  • a spacing element may have a thickness in the range from 0.1 mm to about 100 mm, e.g. in the range from about 1 mm to about 50 mm.
  • a spacing element may be composed of one or more materials.
  • the one or more materials may comprise one or more polymers, e.g. polyamide polymers, polyimides, Poly(p-phenylene oxide) (PPO), a combination thereof, or the like.
  • the material(s) of a spacing element may comprise epoxy or epoxy resin, such as multifunctional epoxy.
  • a spacing element may be made of Nomex paper, such as Nomex Paper 410, 411 , 464.
  • the size of the common core and/or the inductors/coils as a whole depends on different factors. These factors include but are not restricted to power handling, system cooling particularly air-flow, amplitude of noise needed to be suppressed, switching frequency, and available size in the system. Saturation of the filter device may prevent the filter device from performing its basic function (i.e. unbalanced current), thus a careful selection of core size, core material, and number of turns in each filter coils is required in the design of a filter inductor.
  • Using a common core structure for coupling the different filter coils on each converter module decreases the risk of filter saturation due to the natural cancellation of the flux in the common core during system operation.
  • interleaving the switching pulses of each converter module may increase the flux cancellation effect in the common core. Thereby a further reduction of common core size may be realized.
  • the first converter and the second converter may be three phase converters.
  • the first converter may comprise a set of first primary converter terminals and the second converter may comprise a set of second primary converter terminals.
  • Each set of primary converter terminals may comprise three primary converter terminals connected to a corresponding set of secondary filter terminals of the filter device.
  • the first converter and the second converter may be AC/DC converters configured for converting an AC power signal on the primary converter terminal(s) to a DC power signal on the secondary converter terminal(s) and/or vice versa, i.e. converting a DC power signal on the secondary converter terminal(s) to an AC power signal on the primary converter terminals.
  • the converter system may be arranged towards the machine or generator side.
  • the generator may be connected to the first and second primary filter terminals.
  • the converter system may be arranged towards the grid, i.e. primary filter terminals may be connected to the grid, e.g. via a grid transformer.
  • a wind turbine may comprise a first converter system and a second converter system, the wind turbine comprising a generator connected to the first and second primary filter terminals of the first converter system.
  • the first and second primary filter terminals of the second converter system may be connected towards the grid.
  • Fig. 1 schematically illustrates a block diagram of an embodiment of a converter system according to the present invention.
  • the converter system 1 comprises a first converter 2 and a second converter 4 connected to a filter device 6.
  • the first converter 2 has three first primary converter terminals 8, 8', 8", one for each phase in a three phase electrical power signal and is adapted to convert AC signals on the first primary converter terminals 8, 8', 8" to DC on first secondary converter terminals 10, 10', and/or vice versa.
  • the second converter 4 has three second primary converter terminals 12, 12', 12", one for each phase in a three phase electrical power signal and is adapted to convert AC signals on the second primary converter terminals 12, 12', 12" to DC on second secondary converter terminals 14, 14', and/or vice versa.
  • the filter device 6 has first primary filter terminals a u , bn, Cn, second primary filter terminals a 2 i, b 2 i, c 2 i, first secondary filter terminals ai 2 , b 12 , C 12 , and second secondary filter terminals a 22 , b 22 , C 22 .
  • the first secondary filter terminals ai 2 , b 12 , Ci 2 , and the second secondary filter terminals a 22 , b 22 , C 22 are connected to the first primary converter terminals 8, 8', 8" and the second primary converter terminals 12, 12', 12", respectively.
  • Fig. 2 illustrates an embodiment of the filter device employed in the converter system 1.
  • the filter device 6 comprises a first primary filter coil 20 arranged between the first primary filter terminal an and the first secondary filter terminal ai 2 . Further, a second primary filter coil 22 is arranged between the second primary filter terminal a 2 i and the second secondary filter terminal a 22 . Further, the filter device 6 comprises a first secondary filter coil 24 arranged between the first primary filter terminal b and the first secondary filter terminal b 12 . Further, a second secondary filter coil 26 is arranged between the second primary filter terminal b 2 i and the second secondary filter terminal b 22 - Additionally, the filter device 6 comprises a first tertiary filter coil 28 arranged between the first primary filter terminal Cnand the first secondary filter terminal Ci 2 . Further, a second tertiary filter coil 30 is arranged between the second primary filter terminal c 2 i and the second secondary filter terminal C 22 .
  • the first and second primary filter coils 20, 22, the first and second secondary filter coils 24, 26 and the first and second tertiary filter coils 28, 30 are wound around a common core 32.
  • the common core 32 comprises a first E-shaped core element including a first core bridge 34, a first primary core leg 36, a first secondary core leg 38, and a first tertiary core leg 40 extending from the first core bridge 34.
  • the common core 32 comprises a second E-shaped core element including a second core bridge 44, a second primary core leg 46, a second secondary core leg 48, and a second tertiary core leg 50 extending from the second core bridge 44.
  • the common core 32 comprises an end core bridge 52.
  • the first and second primary filter coils 20, 22 are wound around the first primary core leg 36 and the second primary core leg 46, respectively.
  • the first and second secondary filter coils 24, 26 are wound around the first secondary core leg 38 and the second secondary core leg 48, respectively.
  • the first and second tertiary filter coils 28, 30 are wound around the first tertiary core leg 40 and the second tertiary core leg 50, respectively.
  • Fig. 3 and Fig. 4 illustrate a converter system according to the present invention.
  • the converter system 100 is a three phase converter system comprising four three phase converters CONV (1 ), CONV (2), CONV (3) and CONV (4) as described in connection with Fig. 1 , each of the primary converter terminals of the converters CONV (1 ), CONV (2), CONV (3) and CONV (4) being connected to corresponding secondary filter terminals of a filter device 6'.
  • Fig. 4 illustrates an embodiment of the filter device employed in the converter system 100.
  • the filter device 6' comprises a first primary filter coil 20 arranged between the first primary filter terminal an and the first secondary filter terminal ai 2 . Further, a second primary filter coil 22 is arranged between the second primary filter terminal a 2 i and the second secondary filter terminal a 22 . Third primary filter coil 22' is arranged between the third primary filter terminal a 31 and the third secondary filter terminal a 32 , and fourth primary filter coil 22" is arranged between the fourth primary filter terminal a 41 and the fourth secondary filter terminal a 42 . Further, the filter device 6' comprises a first secondary filter coil 24 arranged between the first primary filter terminal bnand the first secondary filter terminal bi 2 .
  • a second secondary filter coil 26 is arranged between the second primary filter terminal b 21 and the second secondary filter terminal b 22 .
  • the filter device 6' comprises a third secondary filter coil 26' arranged between the third primary filter terminal b 3 i and the third secondary filter terminal b 32 , and a fourth secondary filter coil 26" arranged between the fourth primary filter terminal b 4 i and the fourth secondary filter terminal b 42 .
  • the filter device 6' comprises a first tertiary filter coil 28 arranged between the first primary filter terminal Cn and the first secondary filter terminal Ci 2 , and a second tertiary filter coil 30 is arranged between the second primary filter terminal c 2 i and the second secondary filter terminal C 22 of the filter device 6'. Further, a third tertiary filter coil 30' is arranged between the third primary filter terminal c 3 i and the third secondary filter terminal C 32 , and a fourth tertiary filter coil 30" is arranged between the fourth primary filter terminal C 41 and the fourth secondary filter terminal C 42 of the filter device 6'.
  • the filter coils of the filter device 6' are wound on a common core 32'.
  • the common core 32' comprises core bridges 34, 44, 54, 64, and primary core legs 36, 46, 56, 66, secondary core legs 38, 48, 58, 68, and tertiary core legs 40, 50, 60, 70 extending from the core bridges 34, 44, 54, 64, respectively. Further, the common core 32' comprises and an end core bridge 52. The distal ends of the core legs may abut and contact the adjacent core bridge.
  • the embodiments of the filter device of Fig. 2 and 4 facilitate a modular design of a filter device which is an advantage in the construction and design of converter systems.
  • An air gap and/or a spacing element between bridges and adjacent core legs may be included, e.g. between the first core legs 20, 24, 28 and the second core bridge 44, in the design in order to increase the amount of magnetomotive force that the inductors/coils can handle. This will enhance the performance of the inductor during loading condition.
  • the common core may be made of different grades of core material, such as silicon steel, iron alloys. Materials with low loss and high permeability may be employed in order to realize a more compact structure.
  • Fig. 5 schematically illustrates an application of the converter system in a wind turbine.
  • the primary filter terminals a ⁇ , b ⁇ , C 11 , a 21 , b 21 , C 21 of the converter system are connected to a three phase generator 150.
  • Fig. 6 schematically illustrates an application of the converter system in a wind turbine.
  • the primary filter terminals a ⁇ , b 11 t C 11 , a 21 , b 21 , C 21 of the converter system are connected towards the grid.
  • a capacitor bank 152 is arranged in parallel between the converter system 1 and the grid transformer 154.
  • Fig. 7 illustrates a converter system of the present invention.
  • the converter system 200 comprises n converters CONV (1) CONV (n) connected in a parallel configuration with the filter device 6".
  • the n converters have primary converter terminals connected to corresponding secondary filter terminals of the filter device.
  • Fig. 9 illustrates a model of the inter-capacitance present in a common core.
  • the primary filter terminals an, a 2 i, .., a n1 are connected to grid transformer, e.g. grid transformer 154, and secondary filter terminals a 12 , a 22 , • ⁇ a R2 i are connected to converters of the converter system.
  • CONV1_L1 , CONV1_L1X, CONV1_L1Y are equivalent series inductance for a one winding of on one line of a conv(1 ).
  • CONV2J.1 , CONV2_L1X, CONV2J.1Y are equivalent series inductance for a one winding on one line of a conv(2).
  • the capacitors C, C8, C9, C10 are inter- capacitances between windings. This capacitance provides a low impedance path between converters so that each converter will passively current share.
  • Fig. 10 illustrates an embodiment of the filter device employed in the converter system 1.
  • the filter device 106 comprises a first primary filter coil 20 arranged between the first primary filter terminal an and the first secondary filter terminal ai 2 . Further, a second primary filter coil 22 is arranged between the second primary filter terminal a 2 i and the second secondary filter terminal a 22 . Further, the filter device 106 comprises a first secondary filter coil 24 arranged between the first primary filter terminal bnand the first secondary filter terminal bi 2 . Further, a second secondary filter coil 26 is arranged between the second primary filter terminal b 21 and the second secondary filter terminal b 22 .
  • the filter device 106 comprises a first tertiary filter coil 28 arranged between the first primary filter terminal Cnand the first secondary filter terminal C 12 . Further, a second tertiary filter coil 30 is arranged between the second primary filter terminal C 21 and the second secondary filter terminal C 22 .
  • the first and second primary filter coils 20, 22, the first and second secondary filter coils 24, 26 and the first and second tertiary filter coils 28, 30 are wound around a common core 132.
  • the common core 132 comprises a first U-shaped core element including a first core bridge 34, and a first primary core leg 36 and a first tertiary core leg 40 extending from the first core bridge 34.
  • the common core 132 comprises a second U-shaped core element including a second core bridge 44, and a second primary core leg 46 and a second tertiary core leg 50 extending from the second core bridge 44.
  • the common core 132 comprises an end core bridge 52.
  • the first and second primary filter coils 20, 22 are wound around the first primary core leg 36 and the second primary core leg 46, respectively.
  • the first and second secondary filter coils 24, 26 are wound around the first core bridge 34 and the second core bridge 44, respectively.
  • the first and second tertiary filter coils 28, 30 are wound around the first tertiary core leg 40 and the second tertiary core leg 50, respectively.
  • the filter device may comprise a common core comprising four U-shaped core elements.
  • Fig. 11 illustrates an exemplary common core of a filter device.
  • the common core 232 may e.g. be employed in the filter device 6.
  • the common core 232 comprises a number of spacing elements between the distal ends of each core leg and the neighboring core bridge.
  • a first primary spacing element 202 is inserted between the distal end of the first core leg 36 and the second core bridge 44.
  • spacing elements 204, 206, 208, 210, 212 are inserted between the distal ends of core legs and neighboring core bridges.
  • a combination of air gaps and spacing elements may be employed.
  • the common core may comprise one or more core legs comprising a number (e.g. one, two, three, or more) of core leg elements and a number (e.g. one, two, three, or more) of spacing elements.
  • Fig. 12 illustrates an exemplary common core having a number of air gaps/spacing elements distributed along each core leg, i.e. a core leg comprises a number of core leg elements and a number of spacing elements.
  • the common core 332 may e.g. be employed in the filter device 6.
  • the first primary core leg 36 comprises three core leg elements 214 and three spacing elements inserted between core leg elements and the first core bridge 34.
  • the first secondary core leg 38 comprises three core leg elements and three spacing elements inserted between core leg elements and the first core bridge 34.
  • the first tertiary core leg 40 comprises three core leg elements and three spacing elements inserted between core leg elements and the first core bridge 34.
  • the core legs 46, 48, 50 of the second E-shaped core element each comprise three core leg elements and three spacing elements inserted between core leg elements and the second core bridge 44.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Wind Motors (AREA)
  • Filters And Equalizers (AREA)

Abstract

The present invention relates to a converter system, in particular a converter system for a wind turbine, and a wind turbine. A converter system is provided, the converter system comprising a filter device and a first converter having a first primary converter terminal and a first secondary converter terminal, and a second converter having a second primary converter terminal and a second secondary converter terminal. The filter device has at least a first primary filter terminal, a second primary filter terminal, a first secondary filter terminal connected to the first primary converter terminal and a second secondary filter terminal connected to the second primary converter terminal, wherein a first primary filter coil is arranged between the first primary filter terminal and the first secondary filter terminal. Further, a second primary filter coil is arranged between the second primary filter terminal and the second secondary filter terminal, the first primary filter coil and the second primary filter coil being wound around a common core.

Description

CONVERTER SYSTEM FOR AWIND TURBINE
The present invention relates to a converter system, in particular a converter system for a wind turbine.
In recent years, wind turbines have developed rapidly with regard to power and size. The increasingly higher power demands have lead to larger sized wind turbines and components imposing strict requirements on materials and structures. In order to reduce the requirements on materials and structures there is a need for reducing size and weight of wind turbine components. Further, continuous power production is desired even in case of component failure. Accordingly, it is an object of the present invention to provide a converter system with reduced size and weight.
Accordingly, a converter system is provided, the converter system comprising a filter device, a first converter having a first primary converter terminal and a first secondary converter terminal, and a second converter having a second primary converter terminal and a second secondary converter terminal. The filter device has at least a first primary filter terminal, a second primary filter terminal, a first secondary filter terminal connected to the first primary converter terminal and a second secondary filter terminal connected to the second primary converter terminal, wherein a first primary filter coil is arranged between the first primary filter terminal and the first secondary filter terminal. Further, a second primary filter coil is arranged between the second primary filter terminal and the second secondary filter terminal, the first primary filter coil and the second primary filter coil being wound around a common core.
Further, a wind turbine is provided, comprising a converter system and a generator connected to the first and second primary filter terminals of the converter system. Further, a wind turbine is provided, comprising a converter system wherein the first and second primary filter terminals are adapted for connection towards the grid.
It is an important advantage of the present invention that the circulating differential currents in the converter system are reduced.
Further, with common or shared core design there will be inter-capacitance between the windings thus each converter winding is forced to passively current share thus equalize current sharing between converters.
A common or shared core enables reduced mutual inductance between the inductors/coils, thus leading to a smaller size of the converter system which is in particular advantageous in a wind turbine where components of relatively small size are desired.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other features and advantages of the present invention will become readily apparent to those skilled in the art by the following detailed description of exemplary embodiments thereof with reference to the attached drawings, in which:
Fig. 1 schematically illustrates a converter system,
Fig. 2 schematically illustrates an exemplary filter device of the converter system in Fig. 1 Fig. 3 schematically illustrates a converter system,
Fig. 4 schematically illustrates an exemplary filter device of the converter system in Fig. 3,
Fig. 5 schematically illustrates an application of the converter system for the generator side, Fig. 6 schematically illustrates an application of the converter system for the grid side,
Fig. 7 schematically illustrates a converter system,
Fig. 8 schematically illustrates an exemplary filter device of the converter system in Fig. 7, Fig. 9 schematically illustrates inter-capacitance between windings/coils of a single core,
Fig. 10 schematically illustrates an exemplary filter device of the converter system in Fig. 1 , and
Fig. 11 schematically illustrates an exemplary common core. DETAILED DESCRIPTION
The figures are schematic and simplified for clarity, and they merely show details which are essential to the understanding of the invention, while other details have been left out. Throughout, the same reference numerals are used for identical or corresponding parts. The converter system according to the present invention increases the design flexibility due to the modular construction of the converter system. The converter system comprises n converters, where n > 2 The converter system may comprise two converters or more, such as three, four, five, six, seven, eight or more converters. Preferably, each converter has primary converter terminal(s) connected to secondary filter terminals of the filter device. In an embodiment, the converter system comprises four converters having primary converter terminals connected to secondary filter terminals.
The filter device comprises at least one first primary terminal and at least one second primary terminal.
Preferably, the converter system is configured for a three phase power system. The filter device may comprise a set of first primary filter terminals comprising three first primary filter terminals, e.g. for connection to a three phase power grid or a three phase generator. The filter device may comprise a set of second primary filter terminals comprising three second primary filter terminals, e.g. for connection to a three phase power grid or a three phase generator. The filter device may comprise any suitable number of primary filter terminal sets corresponding to the number of converters in the converter system.
The filter device comprises at least one first secondary filter terminal and at least one second secondary filter terminal. The secondary filter terminals of the filter device may be connected to primary converter terminals of a plurality of converters. The filter device may comprise a set of first secondary filter terminals comprising three first secondary filter terminals, e.g. for connection to primary converter terminals of a first converter in a three phase converter system. The filter device may comprise a set of second secondary filter terminals comprising three second secondary filter terminals, e.g. for connection to primary converter terminals of a second converter in a three phase converter system.
The filter device may comprise any suitable number of secondary filter terminal sets corresponding to the number of converters in the converter system, e.g. two, three, four five, six, seven, eight or more secondary filter terminal sets.
The filter device comprises a suitable number of filter coils. The filter device may comprise a first primary filter coil arranged between a first primary filter terminal and a first secondary filter terminal, and a second primary filter coil arranged between a second primary filter terminal and a second secondary filter terminal. Preferably, the first primary filter coil and the second primary filter coil are wound around a common core. For a multiphase, e.g. a three phase, application, the filter device may comprise a first secondary filter coil arranged between a first primary filter terminal and a first secondary filter terminal, and a second secondary filter coil arranged between a second primary filter terminal and a second secondary filter terminal. Preferably, the first secondary filter coil and the second secondary filter coil are wound around a common core.
Further, the filter device may comprise a first tertiary filter coil arranged between a first primary filter terminal and a first secondary filter terminal, and a second tertiary filter coil arranged between a second primary filter terminal and a second secondary filter terminal. Preferably, the first tertiary filter coil and the second tertiary filter coil are wound around a common core.
Preferably, the first primary filter coil and the first secondary filter coil are wound around a common core.
Preferably, the first primary filter coil and the first tertiary filter coil are wound around a common core.
The common core may comprise a first core bridge, and a first primary core leg, an optional first secondary core leg and an optional first tertiary core leg, the first core leg(s) extending from the first core bridge. The common core may comprise an end core bridge. Further, the common core may comprise a second core bridge, and a second primary core leg, an optional second secondary core leg and an optional second tertiary core leg, the second core leg(s) extending from the second core bridge.
The common core may comprise a number of E-shaped core elements, each core element comprising a core bridge, and a primary core leg, a secondary core leg and a tertiary core leg extending from the core bridge. The number of E-shaped core elements may correspond to the number of converters in the converter system.
The common core may comprise a number of U-shaped core elements, each core element comprising a core bridge, and a primary core leg and a tertiary core leg extending from the core bridge. The number of U-shaped core elements may correspond to the number of converters in the converter system. A common core may combine a number of E-shaped core elements and a number of U-shaped core elements.
The filter coils of the filter device may be wound around core legs and/or core bridges of the common core in any suitable configuration in order to obtain desired flux flow in the common core. The distal ends of the core legs of a core element may contact or abut the core bridge of another core element. An air gap may be provided between the distal end of a core leg and a core bridge.
One or more air gaps may be distributed along the length of a core leg to minimize localized heating due to the high reluctance of a single air gap area. An air gap size may range from 0.1 mm to about 100 mm, e.g. in the range from about 1 mm to about 50 mm, depending on the electrical requirements of the filter device design.
A primary filter coil may be wound around the primary core leg of a core element, e.g. the first primary filter coil may be wound around the first primary core leg or the second primary filter coil may be wound around the second primary core leg or both.
A secondary filter coil may be wound around the secondary core leg or the core bridge of a core element. For example, the first secondary filter coil may be wound around the first secondary core leg or around the first core bridge, and/or the second secondary filter coil may be wound around the second secondary core leg or around the second core bridge.
A tertiary filter coil may be wound around the tertiary core leg of a core element. For example, the first tertiary filter coil may be wound around the first tertiary core leg or the second tertiary filter coil may be wound around the second tertiary core leg or both.
One or more filter coils may be wound around an end core bridge. One or more filter coils may be wound around the same core leg or core bridge.
The common core may comprise one or more spacing elements. Spacing element(s) may be inserted in air gap(s) between core elements or constitute a part of a core leg and/or a core bridge. Spacing element(s) may be inserted between the distal end of core legs and an adjacent core bridge. The spacing element(s) may be made of material having low permeability, such as a high temperature Nomex paper or high temperature laminates. A spacing element may have a thickness in the range from 0.1 mm to about 100 mm, e.g. in the range from about 1 mm to about 50 mm.
A spacing element may be composed of one or more materials. The one or more materials may comprise one or more polymers, e.g. polyamide polymers, polyimides, Poly(p-phenylene oxide) (PPO), a combination thereof, or the like.
The material(s) of a spacing element may comprise epoxy or epoxy resin, such as multifunctional epoxy. A spacing element may be made of Nomex paper, such as Nomex Paper 410, 411 , 464.
The size of the common core and/or the inductors/coils as a whole depends on different factors. These factors include but are not restricted to power handling, system cooling particularly air-flow, amplitude of noise needed to be suppressed, switching frequency, and available size in the system. Saturation of the filter device may prevent the filter device from performing its basic function (i.e. unbalanced current), thus a careful selection of core size, core material, and number of turns in each filter coils is required in the design of a filter inductor. Using a common core structure for coupling the different filter coils on each converter module, decreases the risk of filter saturation due to the natural cancellation of the flux in the common core during system operation. Furthermore, interleaving the switching pulses of each converter module may increase the flux cancellation effect in the common core. Thereby a further reduction of common core size may be realized. The first converter and the second converter may be three phase converters.
Accordingly, the first converter may comprise a set of first primary converter terminals and the second converter may comprise a set of second primary converter terminals. Each set of primary converter terminals may comprise three primary converter terminals connected to a corresponding set of secondary filter terminals of the filter device.
The first converter and the second converter may be AC/DC converters configured for converting an AC power signal on the primary converter terminal(s) to a DC power signal on the secondary converter terminal(s) and/or vice versa, i.e. converting a DC power signal on the secondary converter terminal(s) to an AC power signal on the primary converter terminals.
In a wind turbine comprising the converter system and a generator, the converter system may be arranged towards the machine or generator side. Thus, the generator may be connected to the first and second primary filter terminals.
In a wind turbine comprising the converter system, the converter system may be arranged towards the grid, i.e. primary filter terminals may be connected to the grid, e.g. via a grid transformer.
A wind turbine may comprise a first converter system and a second converter system, the wind turbine comprising a generator connected to the first and second primary filter terminals of the first converter system. The first and second primary filter terminals of the second converter system may be connected towards the grid.
Fig. 1 schematically illustrates a block diagram of an embodiment of a converter system according to the present invention. The converter system 1 comprises a first converter 2 and a second converter 4 connected to a filter device 6. The first converter 2 has three first primary converter terminals 8, 8', 8", one for each phase in a three phase electrical power signal and is adapted to convert AC signals on the first primary converter terminals 8, 8', 8" to DC on first secondary converter terminals 10, 10', and/or vice versa. The second converter 4 has three second primary converter terminals 12, 12', 12", one for each phase in a three phase electrical power signal and is adapted to convert AC signals on the second primary converter terminals 12, 12', 12" to DC on second secondary converter terminals 14, 14', and/or vice versa.
The filter device 6 has first primary filter terminals au, bn, Cn, second primary filter terminals a2i, b2i, c2i, first secondary filter terminals ai2, b12, C12, and second secondary filter terminals a22, b22, C22. The first secondary filter terminals ai2, b12, Ci2, and the second secondary filter terminals a22, b22, C22 are connected to the first primary converter terminals 8, 8', 8" and the second primary converter terminals 12, 12', 12", respectively.
Fig. 2 illustrates an embodiment of the filter device employed in the converter system 1. The filter device 6 comprises a first primary filter coil 20 arranged between the first primary filter terminal an and the first secondary filter terminal ai2. Further, a second primary filter coil 22 is arranged between the second primary filter terminal a2i and the second secondary filter terminal a22. Further, the filter device 6 comprises a first secondary filter coil 24 arranged between the first primary filter terminal b and the first secondary filter terminal b12. Further, a second secondary filter coil 26 is arranged between the second primary filter terminal b2i and the second secondary filter terminal b22- Additionally, the filter device 6 comprises a first tertiary filter coil 28 arranged between the first primary filter terminal Cnand the first secondary filter terminal Ci2. Further, a second tertiary filter coil 30 is arranged between the second primary filter terminal c2i and the second secondary filter terminal C22.
The first and second primary filter coils 20, 22, the first and second secondary filter coils 24, 26 and the first and second tertiary filter coils 28, 30 are wound around a common core 32. The common core 32 comprises a first E-shaped core element including a first core bridge 34, a first primary core leg 36, a first secondary core leg 38, and a first tertiary core leg 40 extending from the first core bridge 34. Further, the common core 32 comprises a second E-shaped core element including a second core bridge 44, a second primary core leg 46, a second secondary core leg 48, and a second tertiary core leg 50 extending from the second core bridge 44. Finally, the common core 32 comprises an end core bridge 52. The first and second primary filter coils 20, 22 are wound around the first primary core leg 36 and the second primary core leg 46, respectively. The first and second secondary filter coils 24, 26 are wound around the first secondary core leg 38 and the second secondary core leg 48, respectively. The first and second tertiary filter coils 28, 30 are wound around the first tertiary core leg 40 and the second tertiary core leg 50, respectively.
Fig. 3 and Fig. 4 illustrate a converter system according to the present invention. The converter system 100 is a three phase converter system comprising four three phase converters CONV (1 ), CONV (2), CONV (3) and CONV (4) as described in connection with Fig. 1 , each of the primary converter terminals of the converters CONV (1 ), CONV (2), CONV (3) and CONV (4) being connected to corresponding secondary filter terminals of a filter device 6'.
Fig. 4 illustrates an embodiment of the filter device employed in the converter system 100. The filter device 6' comprises a first primary filter coil 20 arranged between the first primary filter terminal an and the first secondary filter terminal ai2. Further, a second primary filter coil 22 is arranged between the second primary filter terminal a2i and the second secondary filter terminal a22. Third primary filter coil 22' is arranged between the third primary filter terminal a31 and the third secondary filter terminal a32, and fourth primary filter coil 22" is arranged between the fourth primary filter terminal a41 and the fourth secondary filter terminal a42. Further, the filter device 6' comprises a first secondary filter coil 24 arranged between the first primary filter terminal bnand the first secondary filter terminal bi2. Further, a second secondary filter coil 26 is arranged between the second primary filter terminal b21 and the second secondary filter terminal b22. The filter device 6' comprises a third secondary filter coil 26' arranged between the third primary filter terminal b3i and the third secondary filter terminal b32, and a fourth secondary filter coil 26" arranged between the fourth primary filter terminal b4i and the fourth secondary filter terminal b42.
Additionally, the filter device 6' comprises a first tertiary filter coil 28 arranged between the first primary filter terminal Cn and the first secondary filter terminal Ci2, and a second tertiary filter coil 30 is arranged between the second primary filter terminal c2i and the second secondary filter terminal C22 of the filter device 6'. Further, a third tertiary filter coil 30' is arranged between the third primary filter terminal c3i and the third secondary filter terminal C32, and a fourth tertiary filter coil 30" is arranged between the fourth primary filter terminal C41 and the fourth secondary filter terminal C42 of the filter device 6'. The filter coils of the filter device 6' are wound on a common core 32'. The common core 32' comprises core bridges 34, 44, 54, 64, and primary core legs 36, 46, 56, 66, secondary core legs 38, 48, 58, 68, and tertiary core legs 40, 50, 60, 70 extending from the core bridges 34, 44, 54, 64, respectively. Further, the common core 32' comprises and an end core bridge 52. The distal ends of the core legs may abut and contact the adjacent core bridge.
The embodiments of the filter device of Fig. 2 and 4 facilitate a modular design of a filter device which is an advantage in the construction and design of converter systems.
When current flows into each of the coils of the filter device (a1,b1,Ci...an,bn,cn), the current will generate flux lines (Oa1, (Pb1, CpC1.... φan, φbn, Φcn) on the core. By using a common core design, the flux created will basically cancel each other to a certain extent. This reduces the overall flux flowing in the core. Thereby effectively a smaller core can be used compared to when discrete (separate core) filter inductors/coils are employed. By forcing the switching PWM of each individual converter to interleave (phase-shifted) from each other, further flux cancellation can be realized. An air gap and/or a spacing element between bridges and adjacent core legs may be included, e.g. between the first core legs 20, 24, 28 and the second core bridge 44, in the design in order to increase the amount of magnetomotive force that the inductors/coils can handle. This will enhance the performance of the inductor during loading condition. The common core may be made of different grades of core material, such as silicon steel, iron alloys. Materials with low loss and high permeability may be employed in order to realize a more compact structure.
Fig. 5 schematically illustrates an application of the converter system in a wind turbine. The primary filter terminals a^, b^, C11, a21, b21, C21 of the converter system are connected to a three phase generator 150.
Fig. 6 schematically illustrates an application of the converter system in a wind turbine. The primary filter terminals a^, b11 t C11, a21, b21, C21 of the converter system are connected towards the grid. A capacitor bank 152 is arranged in parallel between the converter system 1 and the grid transformer 154. Fig. 7 illustrates a converter system of the present invention. The converter system 200 comprises n converters CONV (1) CONV (n) connected in a parallel configuration with the filter device 6". The n converters have primary converter terminals connected to corresponding secondary filter terminals of the filter device. Fig. 9 illustrates a model of the inter-capacitance present in a common core. The primary filter terminals an, a2i, .., an1 are connected to grid transformer, e.g. grid transformer 154, and secondary filter terminals a12, a22, •■ aR2i are connected to converters of the converter system. CONV1_L1 , CONV1_L1X, CONV1_L1Y are equivalent series inductance for a one winding of on one line of a conv(1 ). CONV2J.1 , CONV2_L1X, CONV2J.1Y are equivalent series inductance for a one winding on one line of a conv(2). The capacitors C, C8, C9, C10 are inter- capacitances between windings. This capacitance provides a low impedance path between converters so that each converter will passively current share.
Fig. 10 illustrates an embodiment of the filter device employed in the converter system 1. The filter device 106 comprises a first primary filter coil 20 arranged between the first primary filter terminal an and the first secondary filter terminal ai2. Further, a second primary filter coil 22 is arranged between the second primary filter terminal a2i and the second secondary filter terminal a22. Further, the filter device 106 comprises a first secondary filter coil 24 arranged between the first primary filter terminal bnand the first secondary filter terminal bi2. Further, a second secondary filter coil 26 is arranged between the second primary filter terminal b21 and the second secondary filter terminal b22. Additionally, the filter device 106 comprises a first tertiary filter coil 28 arranged between the first primary filter terminal Cnand the first secondary filter terminal C12. Further, a second tertiary filter coil 30 is arranged between the second primary filter terminal C21 and the second secondary filter terminal C22.
The first and second primary filter coils 20, 22, the first and second secondary filter coils 24, 26 and the first and second tertiary filter coils 28, 30 are wound around a common core 132. The common core 132 comprises a first U-shaped core element including a first core bridge 34, and a first primary core leg 36 and a first tertiary core leg 40 extending from the first core bridge 34. Further, the common core 132 comprises a second U-shaped core element including a second core bridge 44, and a second primary core leg 46 and a second tertiary core leg 50 extending from the second core bridge 44. Finally, the common core 132 comprises an end core bridge 52. The first and second primary filter coils 20, 22 are wound around the first primary core leg 36 and the second primary core leg 46, respectively. The first and second secondary filter coils 24, 26 are wound around the first core bridge 34 and the second core bridge 44, respectively. The first and second tertiary filter coils 28, 30 are wound around the first tertiary core leg 40 and the second tertiary core leg 50, respectively.
For a converter system comprising four converters, the filter device may comprise a common core comprising four U-shaped core elements.
Fig. 11 illustrates an exemplary common core of a filter device. The common core 232 may e.g. be employed in the filter device 6. The common core 232 comprises a number of spacing elements between the distal ends of each core leg and the neighboring core bridge. A first primary spacing element 202 is inserted between the distal end of the first core leg 36 and the second core bridge 44. Likewise, spacing elements 204, 206, 208, 210, 212 are inserted between the distal ends of core legs and neighboring core bridges. A combination of air gaps and spacing elements may be employed.
The common core may comprise one or more core legs comprising a number (e.g. one, two, three, or more) of core leg elements and a number (e.g. one, two, three, or more) of spacing elements.
Fig. 12 illustrates an exemplary common core having a number of air gaps/spacing elements distributed along each core leg, i.e. a core leg comprises a number of core leg elements and a number of spacing elements. The common core 332 may e.g. be employed in the filter device 6. The first primary core leg 36 comprises three core leg elements 214 and three spacing elements inserted between core leg elements and the first core bridge 34. Likewise, the first secondary core leg 38 comprises three core leg elements and three spacing elements inserted between core leg elements and the first core bridge 34. Further, the first tertiary core leg 40 comprises three core leg elements and three spacing elements inserted between core leg elements and the first core bridge 34. Further, the core legs 46, 48, 50 of the second E-shaped core element each comprise three core leg elements and three spacing elements inserted between core leg elements and the second core bridge 44.
It should be noted that in addition to the exemplary embodiments of the invention shown in the accompanying drawings, the invention may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.

Claims

1. A converter system comprising a filter device and a first converter having a first primary converter terminal and a first secondary converter terminal, and a second converter having a second primary converter terminal and a second secondary converter terminal, the filter device having at least a first primary filter terminal (an), a second primary filter terminal (a2i), a first secondary filter terminal (a12) connected to the first primary converter terminal and a second secondary filter terminal (a22) connected to the second primary converter terminal, wherein a first primary filter coil is arranged between the first primary filter terminal (an) and the first secondary filter terminal (a^), and a second primary filter coil is arranged between the second primary filter terminal (a2i) and the second secondary filter terminal (a22), the first primary filter coil and the second primary filter coil being wound around a common core.
2. A converter system according to claim 1 , wherein the first converter and the second converter are three phase converters, the first converter comprising a set of first primary converter terminals and the second converter comprising a set of second primary converter terminals, each set of primary converter terminals comprising three primary converter terminals connected to corresponding sets of secondary filter terminals of the filter device, the filter device comprising a first secondary filter coil and a first tertiary filter coil arranged between the first primary filter terminals and the first secondary filter terminals, the filter device further comprising a second secondary filter coil and a second tertiary filter coil arranged between the second primary filter terminals and the second secondary filter terminals, the first and second secondary filter coils being wound around a common core.
3. A converter system according to claim 2, wherein the first and second tertiary filter coils are wound around a common core.
4. A converter system according to any of the claims 2-3, wherein the first and second primary filter coils and the first and second secondary filter coils are wound around a common core.
5. A converter system according to any of the preceding claims, wherein the common core comprises at least one E-shaped core element, each E-shaped core element comprising a core bridge, a primary core leg, a secondary core leg, and a tertiary core leg.
6. A converter system according to any of the preceding claims, wherein the common core comprises at least one U-shaped core element, each U-shaped core element comprising a core bridge, a primary core leg, and a tertiary core leg.
7. A converter system according to any of the preceding claims, wherein the common core comprises a first core bridge, a first primary core leg and a first secondary core leg extending from the first core bridge, and an end core bridge.
8. A converter system according to any of the preceding claims, comprising a third converter having a third primary converter terminal, the filter device having a third primary filter terminal, and a third secondary filter terminal connected to the third primary converter terminal, wherein a third primary filter coil is arranged between the third primary filter terminal and the third secondary filter terminal, and being wound around the common core.
9. A converter system according to any of the preceding claims, wherein the first converter and the second converter are AC/DC converters configured for converting an AC power signal on the primary converter terminal(s) to a DC power signal on the secondary converter terminal(s) or vice versa.
10. A wind turbine comprising a converter system according to any of the preceding claims and a generator connected to the first and second primary filter terminals.
11. A wind turbine comprising a converter system according to any of the claims 1-9 and wherein the first and second primary filter terminals are adapted for connection towards the grid.
12. A wind turbine comprising a first converter system comprising a converter system according to any of the claims 1-9 and a generator connected to the first and second primary filter terminals of the first converter system, the wind turbine comprising a second converter system comprising a converter system according to any of the claims 1-9 and wherein the first and second primary filter terminals of the second converter system are connected towards the grid.
PCT/DK2010/000065 2009-05-25 2010-05-22 Converter system for a wind turbine WO2010136033A1 (en)

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