US 12,354,782 B2
Transformer and method of manufacturing a transformer
Thomas Gradinger, Aarau Rohr (CH); and Uwe Drofenik, Zürich (CH)
Assigned to HITACHI ENERGY LTD, Zürich (CH)
Appl. No. 17/289,927
Filed by HITACHI ENERGY LTD, Zürich (CH)
PCT Filed Oct. 30, 2019, PCT No. PCT/EP2019/079719
§ 371(c)(1), (2) Date Apr. 29, 2021,
PCT Pub. No. WO2020/089329, PCT Pub. Date May 7, 2020.
Claims priority of application No. 18203720 (EP), filed on Oct. 31, 2018.
Prior Publication US 2022/0005643 A1, Jan. 6, 2022
Int. Cl. H01F 27/28 (2006.01); H01F 27/34 (2006.01); H01F 41/066 (2016.01)
CPC H01F 27/2823 (2013.01) [H01F 27/34 (2013.01); H01F 41/066 (2016.01)] 12 Claims
OG exemplary drawing
 
1. A transformer comprising:
a first winding arranged around an axis defining an axial direction, and a second winding arranged around the axis,
wherein the second winding comprises a litz wire having an end portion located at an axial end position of the second winding and a middle portion located at an axial middle position of the second winding, the litz wire having a first cross section at the end portion and a second cross section at the middle portion, a direction from the axial middle position pointing towards the axial end position defining an axial outward direction, the first cross section and the second cross section each comprising in a quadrant between the axial outward direction and a direction pointing towards the first winding a curvature extending between the axial outward direction and the direction pointing towards the first winding, wherein the curvature of the first cross section is smaller than the curvature of the second cross section, wherein the end portion of the second winding includes a turn of at least 300° around the axis, wherein the litz wire of the second winding comprises a continuously transitioning litz wire such that the end portion and the middle portion are devoid of any joints.