Power transformer/inductor

• US 6,970,063 B1
• Filed: 02/02/1998
• Issued: 11/29/2005
• Est. Priority Date: 02/03/1997
• Status: Expired due to Fees

• Current Assignee: ABB AB (ABB Limited)
• Original Assignee: ABB AB (ABB Limited)
• Inventors: Holmberg, Par, Leijon, Mats, Fromm, Udo, Ming, Li, Hornfeldt, Sven, Kylander, Gunnar
• Primary Examiner(s): Mai, Anh
• Application Number:
  US09/355,801
• Time in Patent Office: 2,857 Days
• Field of Search: 336/182, 336/185, 336/212, 174/102.SC, 174/15.5, 174/15.6, 174/15.8
• US Class Current: 336/182
• CPC Class Codes: H01F 27/2828 Construction of conductive connections, of leads
• CPC Class Codes: H01F 27/288 Shielding

Abstract

The present invention relates to a power transformer/inductor comprising at least one winding. The windings are designed by means of a high-voltage cable, comprising an electric conductor, and around the conductor there is arranged a first semiconducting layer, around the first semiconducting layer there is arranged an insulating layer and around the insulating layer there is arranged a second semiconducting layer. The second semiconducting layer is earthed at or in the vicinity of both ends (26₁, 26₂; 28₁, 28₂) of each winding and furthermore one point between both ends (26₁, 26₂; 28₁, 28₂) is directly earthed.

Claims

1. A power transformer/inductor comprising:

at least one winding of a high-voltage cable, said winding being formed as a winding turn of said power transducer/inductor, said high-voltage cable having layers and an electric conductor, said layers including;

a first semiconducting layer arranged around the conductor, an insulating layer arranged around the first semiconducting layer and a second semiconductor layer arranged around the insulating layer, the second semiconducting layer being earthed at or in the vicinity of both ends of each winding and a point between both ends being directly earthed.

2. A power transformer/inductor according to claim 1, wherein:

n points, where n is at least 2, per at least one turn of the at least one winding being directly earthed so that electric connections between the n points divide a magnetic flux in the at least one turn into n parts so as to limit losses produced by earthing.

3. A power transformer/inductor according to claim 2, wherein:

the high-voltage cable having a conductor area in an inclusive range of 80 through 3000 mm² and with an outer cable diameter in an inclusive range of 20 through 250 mm.

4. A power transformer/inductor according to claim 3, wherein:

the at least one winding surrounds a cross-section area,

a circumference of each winding turn has a length,

the electric connections between the n earthing points divide the cross-section area into n partial areas and divide said length into n segments, each partial area being bordered by a corresponding segment and at least one electric connection, and

the electric connections between the n points are distributed in such a way that a ratio of a magnetic flux of any one of the n partial areas and a magnetic flux of the cross-section area is equal to a ratio of a length of a corresponding one of the n segments and the length of the circumference.

5. A power transformer/inductor according to claim 4, wherein:

a magnetic flux density is constant throughout a cross-section of the core, and

the electric connections between the n points are distributed in such a way that a ratio of an area of any one of the n partial areas and the area of the cross-section area is equal to the ratio of the length of a corresponding one of the n segments and the length of the circumference.

6. A power transformer/inductor according to claim 1, further comprising:

a magnetizable core.

7. A power transformer/inductor according to claim 1, wherein the power transformer/inductor is built without a magnetizable core.

8. A power transformer/inductor according to claim 1, wherein:

the at least one winding being flexible and said layers adhere to each other.

9. A power transformer/inductor according to claim 8, wherein:

the layers are made of materials with an elasticity and coefficients of thermal expansion such that during operation changes in volume, due to temperature variations, are able to be absorbed by the elasticity of the materials such that the layers retain their adherence to each other during the temperature variations that appear during operation.

10. A power transformer/inductor according to claim 9, wherein:

the materials in the layers having a high elasticity with an E-module less than 500 MPa.

11. A power transformer/inductor according to claim 9, wherein:

the coefficients of thermal expansion being substantially equal.

12. A power transformer/inductor according to claim 9, wherein:

the layers are adhered to one another with a strength equal to or greater than a strength of a weakest material of the first semiconducting layer, the insulating layer and the second semiconducting layer.

13. A power transformer/inductor according to claim 12, wherein:

each semiconducting layer constitutes substantially an equipotential surface.