Rotor for an electric machine, an electric machine and method for manufacturing an electric machine

1. A rotor for an electric machine, comprising:

a rotor core having a plurality of rotor sheets stacked in an axial direction,

wherein each of the plurality of rotor sheets having a plurality of flux guide sections located along a circumferential direction of the rotor sheet,

wherein each of the plurality of flux guide sections including a plurality of flux paths made of a material of high permeance and a plurality of flux barriers made of a material of low permeance located alternately along a radial direction of the flux guide section, and

wherein the plurality of flux guide sections includes:

a first flux guide section in which a first number of the plurality of flux barriers has a bridge interrupting the flux barrier; and

a second flux guide section in which a second number of the plurality of flux barriers has a bridge interrupting the flux barrier,

wherein each of the bridges being made of a material of high permeance, wherein the first number is different than the second number.

2. The rotor according to claim 1 , wherein:

the plurality of rotor sheets are arranged in a plurality of rotor sheet groups, each rotor sheet group including at least one rotor sheet,

rotor sheets of each group are arranged successively in the axial direction,

first flux guide sections are aligned in each rotor sheet group and first flux guide sections of a group are offset by a predetermined angle compared to first flux guide sections of adjacent group.

3. The rotor according to claim 2 , wherein the predetermined angle is defined by an equation

α

=

2

⁢

π

N

FGS

,

where N FGS is a number of flux guide sections in a rotor sheet.

4. The rotor according to claim 2 , wherein each of the plurality of rotor sheets is identical with each other rotor sheet of the plurality of rotor sheets.

5. The rotor according to claim 1 , wherein each flux guide section has an equal number of flux paths and an equal number of flux barriers compared to the other flux guide sections.

6. The rotor according to claim 1 , wherein a width of each bridge is substantially the same.

7. The rotor according to claim 1 , wherein each bridge is positioned such that a quadrature axis of the rotor traverses the bridge.

8. The rotor according to claim 1 , wherein each of the plurality of rotor sheets includes more bridges close to a centre axis of the rotor sheet than further from the centre axis of the rotor sheet.

9. The rotor according to claim 1 , wherein the rotor further includes a pair of end plates each end plate being located at a respective end of the rotor, the plurality of rotor sheets being stacked between the end plates.

10. The rotor according to claim 9 , wherein each of the plurality of rotor sheets includes a plurality of connection apertures, the plurality of rotor sheets are pressed between the end plates by bolts extending through the connection apertures.

11. The rotor according to claim 1 , wherein the rotor is a rotor for a reluctance machine.

12. An electric machine comprising:

a rotor; and

a stator,

wherein the rotor of the electric machine is a rotor according to claim 1 .

13. A method for manufacturing an electric machine according to claim 12 , the method comprising:

providing the plurality of rotor sheets using a punching process.