Patent EA-004162-B1 (EA)
Title: Transformer core
IPC: H01F27/24
Filed: 1999-09-02
Abstract: 1. A transformer core, comprising three legs and yoke parts connecting said legs, wherein the cross-section of said legs is regularly multi-edged with more than four edges, characterised in that the core is made up of rings rolled from strips of constant width, wherein each of said rings make up part of two of said legs. 2. A transformer core according to claim 1, characterised in that said legs have hexagonal cross-section. 3. A transformer core according to claim 2, characterised in that it comprises nine rings. 4. A transformer core according to claim 3, characterised in that it comprises three rings of a first width and a first height and six rings of a second width corresponding to half the first width and a second height corresponding to half the first height. 5. A transformer core according to claim 4, characterised by a first (32), a second (33) and a third (34) ring-shaped part, wherein each ring-shaped part comprises a first ring (32a, 33a, 34a) wound from strips of a first width to a first height, the cross-sections of said rings being rhombic with two angles of 60 degrees, a second ring (32b, 33b, 34b) wound from a strip of a second width essentially corresponding to half the first width, to a second height essentially corresponding to half the first height, said second ring having rhombic cross-section and being positioned on said first ring (32a, 33a, 34a), a third ring (32c, 33c, 34c) wound from a strip of the second width to the second height, said second ring having rhombic cross-section and being positioned in one position on said first ring (32a, 33a, 34a) adjacent to said second ring and in another position on said second ring, said first, second and third ring-shaped part being assembled whereby a three-phase transformer core with three legs with hexagonal cross-sections is formed. 6. A transformer core according to claim 2, characterised in that it comprises seven rings. 7. A transformer core according to claim 6, characterised by a first (22a), a second (23a) and a third (24a) ring wound from strips of a first width to a first height, the cross-sections of said rings being rhombic with two angles of 60 degrees, said first, second and third rings forming yoke parts together forming a triangle, a fourth ring (24b) wound from a strip of said first width to a second height essentially corresponding to half the first height, said fourth ring having rhomboidal cross-section and being positioned on said third ring (24a; a fifth ring (22b; wound from a strip of a second width essentially corresponding to half the first width, to said first height, said fifth ring having rhomboidal cross-section and being positioned en said first ring (22a; a sixth ring (23b) wound from a scrip of the second width to said second height, said sixth ring having rhombic cress-section and being positioned on said second ring (23a), and a seventh ring (23c) wound from a strip of the second widen to said second height, said seventh ring having rhombic cross-section and being positioned on said second ring (23a) and on said sixth ring (23b), whereby a three-phase transformer core with three legs with hexagonal cross-sections is formed. 8. A transformer core according to claim 1, characterised in that said legs have octagonal cross-section. 9. A transformer core according to claim 8, characterised by a first, a second, and a third profile ring, each comprising three rings (42a, 42b, 42c) with two leg parts and two yoke parts, wherein a first ring (42a) having rhombic cross-section in its leg parts with an angle of 45 degrees and with the yoke parts bent 15 degrees in such a direction that the outer side faces of its leg parts are moved towards each other, a second ring (42b) having quadratic cross-sections in its leg parts and being positioned on said first ring, and a third ring (42c) having rhombic cross-sections in its leg parts, a first leg part having 45 degrees lying mainly on said first ring (42a) and a second leg part having 135 degrees lying on said second ring (42b), said first, second and third profile rings being assembled whereby a three-phase transformer core with three legs with octagonal cross-sections is formed. 10. A transformer core according to claim 1, characterised in that said legs have a cross-section with ten edges. 11. A transformer core according to claim 10, characterised by a first, a second, and a third profile ring, each comprising five rings (50a-e) with two leg parts and two yoke parts, wherein a first ring (50a) having rhombic cross-sections in its leg parts with an angle of 36 degrees, a second ring (50b) having rhombic cross-sections in its leg parts with an angle of 72 degrees, a third ring (50c) having rhombic cross-sections in its leg parts with an angle of 108 degrees, a fourth ring (50d) having rhombic cross-sections in its leg parts with an angle of 36 degrees and lying mainly on the first ring (50a) and having its yoke parts turned outwards 24 degrees, and a fifth ring (50e) having rhombic cress-sections in its leg carts with an angle of 144 degrees when it lies on the third ring (50c) but rhombic cross-section with an angle of 72 degrees when it lies outside the fourth ring (50c), and a channel (51) suitable for cooling the leg outside of the fifth ring (50e), said first, second and third profile rings being assembled whereby a three-phase transformer core with three legs with ten-sided cross-sections is formed. 12. A transformer core according to claim 11, characterised by cooling channels (52a, 52b, 53a, 53b) caused by giving the outer part of the third ring (50c) a rhombic cross-section with an angle of 72 degrees and by displacing another outer leg part of the third ring toward the fifth ring (50e) when it goes within the complete leg. 13. A transformer core according to claim 10, characterised by multi-edged cross-sections of their legs and profile rings comprising a first cluster of rings with rhombic cross-sections with different angles but in their leg parts turned the same angle and attached to the multi-edged cross-section, and inside a second cluster of rings with rhombic cross-section with different angles, but in their leg parts turned the same angle and attached to the first cluster and so on until innermost there arises space for rings, which in one of their leg parts is given a cross-section and turning differently from those in the other leg part. 14. A transformer core according to claim 1, characterised in that all rings have a rhombic cross-section with two angles of 60 degrees and two angles of 120 degrees. 15. A transformer core according to claim 1, characterised by an additional core (70) of strips between windings brought together at the top and the bottom of the core. 16. A transformer core according to claim 1, characterised by an additional core in the center line of at least one strip pole, and if many, arranged three and three in a package (figs. 8 and 9), which poles are bent to each yoke. 17. A transformer core according to claim 1, characterised in that segments between the cross-sections of the legs and a circumscribed circle are partly filled by thin rings and/or slightly broader strips.