Helical winding with more uniform field utilization

1. A stator for an AC electric machine with a number of magnetic poles, the stator comprising:

a central axis A;

a stator winding with a plurality of conductor turns;

wherein the individual conductor turns are grouped into a total of n electrical strands;

the individual conductor turns of a respective electrical strand define a first conductor branch and a second conductor branch;

the first conductor branch and the second conductor branch are arranged helically around the central axis over at least half of their respective lengths; and

the helically arranged conductor branches each have a pitch greater than a product of an axial length of the helical conductor branches and the number of magnetic poles.

2. The stator as claimed in claim 1 , wherein:

the stator winding includes electrically conductive connecting conductors in axial end regions between the first conductor branches and the second conductor branches; and

the connecting conductors have both a radial direction component and a peripheral direction component.

3. The stator as claimed in claim 2 , wherein the connecting conductors are arranged such that, for each strand, there is at least one superordinate coil arrangement.

4. The stator as claimed in claim 1 , wherein:

the stator winding has a number i of conductor turns; and

the number i corresponds either: to a product of the pole number and of the strand number n; or to one half of a product of the pole number and of the strand number n.

5. The stator as claimed in claim 4 , wherein:

each of the conductor turns has a first conductor branch and a second conductor branch;

the respective conductor branches are wound helically over their axial length l with an angle α, giving a pitch p; and

where the value of α is at least α=360°/p−2*360°/i and smaller than α=360°/p.

6. The stator as claimed in claim 1 , wherein:

the first conductor branches of the individual conductor turns are arranged on a common inner cylinder surface; and

the second conductor branches of the individual conductor turns are arranged on a common outer cylinder surface.

7. The stator as claimed in claim 6 , wherein:

the first conductor branches on the inner cylinder surface have a common first winding direction; and

the second conductor branches on the outer cylinder surface have a common second winding direction opposite the first winding direction.

8. The stator as claimed in claim 1 , wherein the number n of strands is greater than three.

9. The stator as claimed in claim 1 , wherein the stator winding comprises an air gap winding.

10. An electric machine comprising:

a rotor; and

a stator having a central axis;

wherein the stator includes a stator winding with a plurality of conductor turns;

wherein individual conductor turns of the plurality of conductor turns are grouped into a total of n electrical strands;

the individual conductor turns of a respective electrical strand define a first conductor branch and a second conductor branch;

the first conductor branch and the second conductor branch are arranged helically around the central axis over at least half of their respective lengths; and

the helically arranged conductor branches each have a pitch greater than a product of an axial length of the helical conductor branches and the number of magnetic poles.

11. The electric machine as claimed in claim 10 , wherein the rotor generate a magnetic field with p poles.

12. The electric machine as claimed in claim 11 , wherein the rotor comprises a superconductive excitation winding.

13. The electric machine as claimed in claim 10 , further comprising an inverter for creating or removing a phase shift between currents flowing in individual strands of the stator winding.

14. The electric machine claimed in claim 10 , wherein the number p of magnetic poles is between 2 and 12.