Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F27/00—Details of transformers or inductances, in general
  • H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F27/00—Details of transformers or inductances, in general
  • H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
  • H01F27/36—Electric or magnetic shields or screens
  • H01F27/366—Electric or magnetic shields or screens made of ferromagnetic material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F27/00—Details of transformers or inductances, in general
  • H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
  • H01F2027/348—Preventing eddy currents

Definitions

• the present disclosure relates to atransformer, in particular to a transformer for application in power grid systems, for example it relates to high voltage transformers.
• Transformers are used in power systems for voltage level control.
• a transformer is used to step up and step down voltage in electric power systems in order to transmit and utilize electrical power.
• Embodiments of the disclosure relate to a transformer.
• the transformer comprises a core.
• the transformer comprises a winding.
• the winding is wound around a winding axis extending along the core.
• the transformer comprises an eddy losses reducer.
• the eddy losses reducer is arranged at an axial end of the winding.
• the eddy losses reducer in the following also called “reducer”, comprises a non-ferromagnetic main body.
• the reducer comprises a ferro-magnetic layer surrounding the main body.
• radial flux generate axial forces. For example, these forces cause vibration and resulting noises.
• radial flux leads to losses and hotspots.
• the eddy losses reducer is arranged to reduce losses, hotspots and thus also forces. Due to the eddy losses reducer, the magnetic flux generated by the winding generates less eddy losses in conductors of the winding and thus less axial forces as well.
• the eddy losses reducer is arranged at the axial end, where radial flux is higher and tends to go out from the winding and reach the core or the tank. This is reduced by the eddy losses reducer. Thus, losses and hotspots generated by the radial flux at the end of the winding are reduced.
• the eddy losses reducer which can also be called “magnetic flux collector”, is used to reduce the eddy radial losses in the winding and/or the exposed area of the core.
• the eddy losses reducer can an integral part of an equipotential ring which is arranged at the axial end of the winding.
• the equipotential ring is extended by an eddy losses reducing functionality. Therefore, the ferromagnetic layer is provided which surrounds the non-ferromagnetic main body.
• the ferromagnetic layer comprises iron or another ferromagnetic metal or material.
• the eddy losses reducer comprises a ring segment shape.
• the eddy losses reducer comprises an opening where two ends of the eddy losses reducer are arranged opposite each other and are arranged at a distance from each other.
• the eddy losses reducer is interrupted at the opening. For example, ring flows along the eddy losses reducer are avoided.
• the ring segment shape may be circular or elliptic.
• the ferromagnetic layer comprises a thickness between 50 ⁇ m and 9 cm. Other thicknesses are possible, in particular between 25 ⁇ m and a few centimeters. The thickness, for example, is measured along the winding axis or transverse to it.
• the ferromagnetic layer comprises a metal strip.
• the metal strip is rolled around the main body.
• the metal strip comprises one iron sheet or more iron sheets.
• the metal strip consists of an iron sheet or a plurality of iron sheets.
• the iron sheets are rolled around the non-ferromagnetic main body.
• the metal strip comprises a thickness between 50 ⁇ m and 9 cm in a vertical direction of the metal strip, whereby the vertical direction is thinner than the two transverse directions, which are aligned perpendicular to the vertical direction.
• the iron sheet is made of ferromagnetic material.
• the iron sheet compriese electrical steel like the one used to produce transformer cores and including amorphous ones.
• the transformer can comprise an adhesive connection to fix the metal strip.
• the adhesive connection fixes the metal strip to the main body.
• the adhesive connection can be useful to restrict themovement of the metal strip during operation.
• the adhesive connection is configured to reduce vibrations of the metal strip, if needed.
• the metal strip, which is rolled around the main body, is glued to reduce vibrations.
• the main body comprises an electrically insulating material.
• the main body is, for example, made of a non-ferromagnetic electrically insulating material to not, or only insignificantly, influence the magnetic field generated by the winding.
• the main body comprises at least one of wood and plastic.
• the main body consists of at least one of wood and plastic.
• the main body is made of laminated wood or transformer board.
• the eddy losses reducer comprises a covering layer.
• the covering layer surrounds the ferromagnetic layer.
• the ferromagnetic layer is arranged between the covering layer and the main body.
• the covering layer protects the ferromagnetic layer and/or forms an electrical insulation.
• the covering layer is used to smooth the surface.
• the covering layer comprises at least one of paper, textile, and plastic.
• the covering layer comprises crepe paper.
• the covering layer comprises a carbon layer and/or a further metallic layer.
• the carbon layer and/or the further metallic layer is formed as a coating of the covering layer.
• the carbon layer and/or further metallic layer faces the ferromagnetic layer.
• the covering layer comprises several layers.
• the covering layer comprises a paper layer, a carbon and/or metallic layer, and a further paper layer.
• the carbon layer and/or the further metallic layer is used to keep the voltage of the eddy losses reducer at a defined voltage during operation.
• the winding is arranged directly adjacent to and at a distance to the core.
• the eddy losses reducer is arranged at the winding which is arranged nearest to the core.
• the eddy losses reducer is arranged at the winding with the smallest diameter.
• the transformer comprises a plurality of windings around the core.
• respective eddy losses reducers are arranged on each of the windings.
• respective eddy losses reducers are arranged only on a part of the windings.
• the respective eddy losses reducer is arranged on the windings, which are arranged facing the core.
• windings that are arranged facing away from the core do not have an eddy losses reducer.
• the eddy losses reducers are arranged on the windings with the smallest radii and not on windings with a larger radius which are arranged further away from the core.
• the transformer comprises a second core.
• the transformer comprises a second winding wound around a second winding axis extending along the second core.
• the transformer comprises a second eddy losses reducer.
• the second eddy losses reducer for example, is designed correspondingly to the first eddy losses reducer.
• the second eddy losses reducer is arranged at an axial end of the second winding. It is possible that one eddy losses reducer surrounds the first core and a second eddy losses reducer surrounds the second core. It is possible that a plurality of eddy losses reducers surrounds the first core and a further plurality of eddy losses reducers surrounds the second core.
• respective eddy losses reducers are arranged on both axial ends of the windings around the first core, or at just one single axial end.
• respective second eddy losses reducers are arranged at both axial ends of the second windings around the second core, or at just one single axial end of the second windings.
• the winding is a primary winding or a secondary winding.
• the transformer comprises a tertial winding, which is arranged without an eddy losses reducer.
• the voltage ratings of one or more of the windings of the transformer are above 1 kV such that the voltage ratings of all of the windings of the transformer are above 1 kV.
• Figure 1 shows a schematic cross-section of a transformer according to an embodiment.
• Figures 2 to 4 show different views of an eddy losses reducer according to an embodiment.
• FIG. 1 schematically shows parts of a transformer 100.
• the transformer 100 is enclosed in a tank (not explicitly shown) which, for example, is filled with a dielectric fluid.
• the transformer 100 comprises a first core 101 and a second core 121. Windings 102, 103, 104 are arranged around the first core 101. Further windings 122, 123, 124 are arranged around the second core 121.
• the first core 101 and the windings 102, 103, 104 are symmetric around a winding axis 105.
• the second core 121 and the windings 122, 123, 124 are symmetric around a second winding axis 125.
• the winding 102 extends along the winding axis 105 and terminates in an axial end 106 and an opposite axial end 107.
• the winding 103 ends in an axial end 108 and an opposite axial end 109.
• the windings 122 and 123 correspondingly terminate in respective axial ends 126, 127, 128, 129.
• the winding 102 has a smaller diameter than the remaining windings 103, 104, which are arranged around the first core 101.
• the coil 102 is located closest to the first core 101.
• the winding 102 is arranged at a distance 150 from the first core 101.
• the windings 122 has a smaller diameter than the remaining windings 123, 124, which are arranged around the second core 121.
• the coil 122 is located closest to the second core 121.
• the transformer 100 comprises an eddy losses reducer 200 which is arranged at the axial end 106 of the winding 102. Further eddy losses reducers 200 are arranged at the axial ends 107, 108, 109 around the first core 101. Around the second core 121 eddy losses reducers 200 are arranged at the axial ends 126, 127, 128 and 129.
• no eddy losses reducers 200 are arranged at the winding 104 and the winding 124.
• the winding 104 around the first core 101 has no associated eddy losses reducer 200.
• the winding 124 around the second core 121 has no associated eddy losses reducer 200.
• Eddy losses reducers 200 are arranged at the windings 102, 103 that are arranged radially between the first core 101 and the winding 104.
• Eddy losses reducers 200 are arranged at the windings 122, 123 that are arranged radially between the second core 121 and the winding 124.
• the number of eddy losses reducers 200 is purely exemplary and may deviate from the number shown in Figure 1 .
• less than the shown eddy losses reducers 200 may be provided or more.
• just one single eddy losses reducer 200 is provided around each core 101, 121.
• Respective eddy losses reducers 200 can be arranged at each opposite end or only at one end and the other end is free of an eddy losses reducer.
• the number of eddy losses reducers 200 around core 101 can be different from the number of eddy losses reducers 200 around the second core 121.
• the transformer 100 comprises more than two cores 101, 121, for example three cores with respective windings or more.
• the transformer 100 comprises three cores with respective windings and 12 eddy losses reducers 200, four eddy losses reducers 200 per core, two windings with two eddy losses reducers 200 each per core.
• the eddy losses reducer 200 comprises a ring-like shape 203.
• the eddy losses reducer 200 comprises a center 213.
• the center 213 of the shape 203 of the eddy losses reducer 200 lies on the winding axis 105 or the winding axis 125 respectively.
• the eddy losses reducer 200 extends in the ring-like shape or ring segment shape 203 around the respective core 101, 121.
• the eddy losses reducer comprises a radius around the center 213 with a value between 30 cm and 3 meters, depending on the transformer type of the transformer 100.
• the eddy losses reducer 200 for example is not formed as a closed ring but with the ring segment shape 203.
• the eddy losses reducer 200 comprises an opening 204.
• two ends 205, 206 of the eddy losses reducer 200 are arranged facing each other and opposite each other.
• the two ends 205, 206 are arranged at a distance 207.
• the distance 207 comprises values from 0.5 mm to 25 cm. Other ranges and values for the distance 207 are possible.
• FIG 3 shows a cross-section of the eddy losses reducer 200 along the line A of Figure 2 .
• the eddy losses reducer 200 comprises a main body 201.
• the main body 201 comprises the ring segment shape 203.
• the main body 201 comprises or consists of a non-ferromagnetic material.
• the main body is made out of wood and/or plastic.
• the main body 201 is made out of laminated wood and/or transformer board.
• the main body 201 is configured as a stable body which supports the eddy losses reducer 200.
• a first layer 202 surrounds the main body 201.
• the first layer 202 comprises or consists of a ferromagnetic material.
• the first layer 202 comprises or consists of a metal, for example a metal strip 209 ( Figure 4 ).
• the first layer 202 comprises iron or consists of iron.
• the first layer 202 is an iron sheet and can just be made of ferromagnetic material.
• the first layer 202 comprises electrical steel like the one used to produce transformer cores and including amorphous ones.
• An optional further layer 212 surrounds the first layer 202.
• the further layer 212 comprises or consists of a carbon layer and/or a further metallic layer.
• the further layer 212 comprises an electrically conductive material.
• a covering layer 211 surrounds the further layer 212 and the first layer 202.
• the covering layer comprises or consists of paper, textile or plastic.
• the further layer 212 covers the covering layer 211 at a surface which faces the first layer 202.
• the covering layer 211 comprises carbonized paper such that the further layer 212 is a carbon layer on the paper.
• Figure 4 shows an example of the eddy losses reducer 200 in which the ferromagnetic layer 202 is made out of the metal strip 209.
• the metal strip 209 is wound around the main body 201, such that the metal strip 209 covers the main body 201.
• a plurality of metal strips 209 is wound around the main body 201 to achieve a desired thickness 208 ( Figure 3 ) of the ferromagnetic layer 202.
• the metal strip 209 is wound around the main body 201 several times to achieve the desired thickness 208.
• the thickness 208 comprises a value between 50 ⁇ m and 9 cm, for example between 1 mm and 10 mm.
• the metal strip 209 comprises a thickness between 0.01 mm and 0.6 mm .
• the thickness of the metal strip comprises a value between 10 and 15 ⁇ m.
• the metal strip 209 is a rolled iron sheet.
• the metal strip 209 is fixed by an adhesive connection 210.
• the adhesive connection 210 is omitted.
• the adhesive connection 210 can glue the metal strip layer 209 to itself and/or to the main body 201.
• An adhesive fixes the metal strip layer 209.
• a vibration of the metal strip 209 can be reduced, if needed depending on the design. This reduces noise emissions.
• the eddy losses reducer 200 also serves as an equipotential ring to reduce electrical stress at the axial ends 106 to 109, 126 to 129 of the respective windings 102, 103, 104, 122, 123, 124.
• the eddy losses reducer 200 acts as the equipotential ring and as a magnetic shunt. Transformer eddy losses can be easily reduced. By reducing the eddy losses, the efficiency of the transformer 100 is improved. Due to the reduced eddy losses, material savings can be achieved.
• the iron used for the metal strip 209 for example comprises an amorphous iron.
• the iron used for the metal strip 209 is of the same type of iron as used for the core 101, 102.
• the eddy losses reducer 200 is simple to implement and achieves lower losses and/or lower forces in the transformer.
• the material requirements for the eddy losses reducer 200 are reduced compared to other solutions. Efficiency and reliability of the transformer 100 can be increased without any need for a substantive design change of the transformer 100.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Coils Of Transformers For General Uses (AREA)

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Citations (4)

• 2024
  • 2024-01-26 EP EP24154154.9A patent/EP4593045A1/fr active Pending
  • 2024-11-28 WO PCT/EP2024/083924 patent/WO2025157453A1/fr active Pending

Patent Citations (4)

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