The present invention provides a generator comprising winding arrangements, each winding arrangement comprising at least an inner coil and an outer coil constituting a concentric structure of coils. The inner coil is constituted by an inner conductor and the outer coil is constituted by an outer conductor, the inner and outer conductors being connected in series. The inner conductor, which is wound around a tooth, has a smaller electrical resistance per unit length than the outer conductor.
1. A generator, comprising:
winding arrangements of the generator, each winding arrangement comprising at least an inner coil and an outer coil,
wherein the inner coil is constituted by an inner conductor and the outer coil is constituted by an outer conductor,
wherein the inner conductor is wound around a tooth and the entire outer conductor is wound around the entire inner conductor and the tooth such that a concentric structure of coils is defined by the inner conductor wrapped around the tooth and the outer conductor wrapped around the inner conductor,
wherein the inner and outer conductors are connected in series, and
wherein the inner conductor has a constant cross-section and a smaller electrical resistance per unit length than the outer conductor.
2. The generator according to claim 1 , wherein the inner conductor has a larger cross-section than the outer conductor.
3. The generator according to claim 2 , wherein the cross-section of the inner conductor has a greater height than the cross-section of the outer conductor.
4. The generator according to claim 2 , wherein the cross-section of the inner conductor has a greater width than the cross-section of the outer conductor.
5. The generator according to claim 2 , wherein the ratio of the cross-section of the outer conductor to the cross-section of the inner conductor is between 50% and 99%.
6. The generator according to claim 5 , wherein the ratio of the cross-section of the outer conductor to the cross-section of the inner conductor is between 60% and 75%.
7. The generator according to claim 1 , wherein the inner conductor has a greater electrical conductivity than the outer conductor.
8. The generator according to claim 1 , wherein each winding arrangement further comprises one or more intermediate coils between the inner and the outer coil in the concentric structure of coils, and wherein each intermediate coil is constituted by an intermediate conductor having an electric resistance per unit length lying in between the electric resistance per unit length of the inner conductor and the electric resistance per unit length of the outer conductor.
9. The generator according to claim 8 , wherein each intermediate conductor has a cross-section lying in between the cross-section of the inner conductor and the cross-section of the outer conductor.
10. The generator according to claim 8 , wherein each intermediate conductor has an electric conductivity lying in between the electric conductivity of the inner conductor and the electric conductivity of the outer conductor.
11. The generator according to claim 1 , comprising a rotor and a stator, wherein the rotor comprises permanent magnets and the stator comprises the winding arrangements with concentric structure of coils.
12. The generator according to claim 3 , wherein the cross-section of the inner conductor has a greater width than the cross-section of the outer conductor.
13. The generator according to claim 2 , wherein the inner conductor has a greater electrical conductivity than the outer conductor.
14. The generator according to claim 2 , wherein each winding arrangement further comprises one or more intermediate coils between the inner and the outer coil in the concentric structure of coils, and wherein each intermediate coil is constituted by an intermediate conductor having a cross-section lying in between the cross-section of the inner conductor and the cross-section of the outer conductor.
15. The generator according to claim 7 , wherein each winding arrangement further comprises one or more intermediate coils between the inner and the outer coil in the concentric structure of coils, and wherein each intermediate coil is constituted by an intermediate conductor having an electric conductivity lying in between the electric conductivity of the inner conductor and the electric conductivity of the outer conductor.
16. The generator according to claim 9 , wherein each intermediate conductor has an electric conductivity lying in between the electric conductivity of the inner conductor and the electric conductivity of the outer conductor.
17. The generator according to claim 1 , wherein the generator is configured for use with a wind or steam turbine.