Magnetic cap element for a stator of a generator

1. A stator system of a wind turbine generator, the stator system comprising:

a stator housing element, the stator housing element comprising a first surface comprising slots to which stator windings are attachable, and a second surface radially opposite to the first surface, the second surface comprising an axially extending groove,

a cap element mounted to the stator housing element to close the groove such that a channel for guiding a cooling fluid within the groove is formed, and

an insulation layer located between the cap element and an inner volume of the groove, wherein the insulation layer is impregnated with resin, and wherein the insulation layer comprises an expandable fibrous material arranged such that upon impregnation with the resin the insulation layer expands and acts as a spring to fix the cap element to the stator housing element,

wherein the cap element comprises a magnetic material.

2. The stator system according to claim 1 , further comprising

a resin layer that covers the stator housing element and the cap element.

3. The stator system according to claim 1 , further comprising

wherein the stator housing element comprises a first three dimensional contour,

wherein the cap element comprises a second three dimensional contour, and

wherein the second three dimensional contour is complementary to the first three dimensional contour in such a way that the cap element is slidably connectable to the first three dimensional contour for fixing the cap element to the stator housing element.

4. The stator system according to claim 3 ,

wherein the first three dimensional contour of the stator housing element comprises a guiding notch, and

wherein the second three dimensional contour of the cap element comprises an edge section, and

wherein the guiding notch is formed in such a way that the edge section of the cap element is slidably insertable into the guiding notch for fixing the cap element to the stator housing element.

5. The stator system according to claim 4 ,

wherein the edge section of the cap element comprises a wedge profile,

wherein the guiding notch comprises a V-shaped profile, and

wherein the V-shaped profile corresponds to the wedge profile of the edge section of the cap element.

6. The stator system according to claim 1 ,

wherein the groove is rectangular.

7. The stator system according to claim 1 ,

wherein the groove comprises a profile configured to a profile of a cooling pipe that is insertable into the groove.

8. The stator system according to claim 1 , wherein the stator housing element is formed by a plurality of stator laminations.

9. The stator system according to claim 1 , wherein the cap element is configured such that electromagnetic flux flows from the housing element along the magnetic cap element and is not interrupted by the groove formed into the stator housing element.

10. A method for manufacturing a stator system for a wind turbine generator, the method comprising

forming an axially extending groove in a second surface of a stator housing element of the stator system, wherein the stator housing element comprises a first surface comprising slots to which stator windings are attachable, the first surface being radially opposite to the second surface,

mounting a cap element to the stator housing element for closing the groove such that a channel for guiding a cooling fluid within the groove is formed,

interposing an insulation layer between the cap element and an inner volume of the groove, and

impregnating the insulation layer with resin, wherein the insulation layer comprises an expandable fibrous material such that upon impregnation of the insulation layer with the resin the insulation layer expands and acts as a spring to fix the cap element to the stator housing element,

wherein the cap element comprises a magnetic material.

11. The method according to claim 10 ,

impregnating the stator housing element and the cap element via a resin impregnation process.

12. The method according to claim 10 , wherein the stator housing element is formed by a plurality of stator laminations.

13. The method according to claim 10 , wherein the cap element is arranged such that electromagnetic flux flows from the housing element along the magnetic cap element and is not interrupted by the groove formed into the stator housing element.