Rotor body for a permanent magnet machine
A rotor for an electrical machine extends along a longitudinal axis between a drive end and an axially opposite non-drive end, the drive end being attachable to a torque input. The rotor includes: a rotor body extending axially between the drive end and the non-drive and extending in a radial direction orthogonal to the longitudinal axis between an inner side and an outer side, plurality of permanent magnets attached to the inner side a circumferentially distributed about the longitudinal axis, wherein the rotor body includes a plurality of lamination sheets stacked along the longitudinal axis.
1. A rotor for an electrical machine extending along a longitudinal axis between a drive end and an axially opposite non-drive end, the drive end being attachable to a torque input, the rotor comprising:
a rotor body extending axially between the drive end and the non-drive and extending radially orthogonal to the longitudinal axis between an inner side and an outer side; and
a plurality of permanent magnets attached to the inner side circumferentially distributed about the longitudinal axis
wherein the rotor body includes a plurality of lamination sheets stacked along the longitudinal axis;
wherein the rotor body includes a plurality of axial strengthening elements inserted in respective axial holes extending across two or more lamination sheets of the plurality of lamination sheets;
wherein the axial strengthening elements further comprise pins inserted in respective pin holes, each pin and pin hole extending across two or more lamination sheets of the plurality of lamination sheets.
2. The rotor according to claim 1 , wherein the axial strengthening elements comprises tensioning bolts for applying a compression to the plurality of lamination sheets along the longitudinal axis, the tensioning bolts being inserted in respective tensioning holes, each bolt and hole extending axially between the drive end and the non-drive end.
3. The rotor according to claim 2 , wherein the tensioning bolts and holes are provided on the outer side of the rotor body.
4. The rotor according to claim 3 , wherein the outer side of the rotor body further comprises a plurality of radial protrusions axially extending between the drive end and the non-drive end, each of the tensioning holes being at least partially housed in one of the radial protrusions.
5. The rotor according to claim 1 , wherein the inner side includes a plurality of attaching means for attaching the plurality of permanent magnets to the rotor body.
6. The rotor according to claim 1 , wherein the inner side includes a plurality of axial cavities extending between the drive end and the non-drive end for housing the plurality of permanent magnets.
7. The rotor according to claim 1 , wherein the rotor body further comprises two annular plates, respectively provided at the drive end and at the non-drive end, wherein one of the two annular plates is a brake disc, the two annular plates being fixed to the plurality of lamination sheets stacked along the longitudinal axis by the plurality of tensioning bolts.
8. The rotor according to claim 1 , wherein at least a portion of the plurality of lamination sheets are welded to each other.
9. The rotor according to claim 1 , wherein a coating is provided at least over one of the inner side and the outer side.
10. An electrical machine having a stator and a rotor according to claim 1 , the electrical machine comprising an air gap interposed between the stator and the inner side of the rotor body.
11. A wind turbine including an electrical machine according to claim 10 , the electrical machine being an electrical generator, the drive end of the rotor being connected with a wind rotor of the wind turbine for providing the torque input.
12. A method of manufacturing a rotor for an electrical machine, the rotor extending along a longitudinal axis between a drive end and an axially opposite non-drive end, the drive end being attachable to a torque input, the method comprising:
manufacturing a plurality of permanent magnets;
manufacturing a plurality of lamination sheets, each lamination sheet having a lamination inner border and a lamination outer border;
stacking the plurality of lamination sheets along the longitudinal axis for forming a rotor body extending axially between the drive end and the non-drive and extending in a radial direction orthogonal to the longitudinal axis between an inner side and an outer side, the stacked lamination inner borders forming the inner side and the stacked lamination outer borders forming the outer side;
inserting a plurality of axial strengthening elements in respective axial holes extending across two or more lamination sheets of the plurality of lamination sheets, the plurality of axial strengthening elements comprising pins inserted in respective pin holes, each pin and pin hole extending across two or more lamination sheets of the plurality of lamination sheets; and
attaching the plurality of permanent magnets to the inner side of the rotor body.
13. The method according to claim 12 , further comprising applying a compression to the plurality of lamination sheets along the longitudinal axis after the stacking.