Electric machine having a low-mass design in magnetically active parts
An electric machine includes a first magnetic pole with an arrangement of interposed magnetically active layers and magnetically inactive layers, and a second magnetic pole movable relative to the first magnetic pole and spaced from the first magnetic pole by a gap. An electrical conductor operates as a coupling element between an electrical circuit and a magnetic circuit. At an operating time, a common useful magnetic flux for electromechanical energy conversion flows through the magnetic circuit composed of the first magnetic pole, the gap and the second magnetic pole. The magnetically inactive layers have a lower average density than the magnetically active layers. A ratio (k) of the total volume of the magnetically active layers to the combined total volume of the magnetically active and inactive layers fulfills the condition 0.5≦k≦0.8 A method for producing an electric machine are also disclosed.
1. An electric machine comprising:
a first magnetic pole comprising an arrangement of layers having magnetically active layers with a total volume (V a ) and magnetically inactive layers with a total volume (V i ) which have a lower average density than the magnetically active layers, wherein the magnetically active layers and the magnetically inactive layers repeat in a specified order with a period p, and wherein a ratio (k) of the total volume (V a ) of the magnetically active layers to the combined total volume (V a +V i ) of the magnetically active layers and the magnetically inactive layers fulfills the condition 0.5≦k≦0.8,
a second magnetic pole confronting the first magnetic pole and movable relative to the first magnetic pole, and
a gap having a length (l S ) extending between an end of the first magnetic pole and an end of the confronting second magnetic pole in a direction parallel to a magnetically active or magnetically inactive layer, and
an electrical conductor constructed as a coupling element between an electrical circuit and a magnetic circuit,
wherein at an operating time, the magnetic circuit comprises the first magnetic pole, the gap and the second magnetic pole, and is permeated by a common useful magnetic flux for electromechanical energy conversion.
2. The electric machine of claim 1 , wherein the magnetically active layers have thicknesses (b Ai ), wherein
b Ai ≦S,
wherein S is in a range between l S /20 and l S /4, with l S being the length of the gap.
3. The electric machine of claim 1 , wherein a permanent magnet comprising a first and a second permanent-magnet pole is arranged in the gap in abutting relationship with the second magnetic pole, with a first permanent-magnet pole facing the second magnetic pole.
4. The electric machine of claim 1 , wherein the magnetically inactive layers are spacers.
5. The electric machine of claim 1 , wherein the magnetically active layers are affixed to the magnetically inactive layers.
6. The electric machine of claim 1 , further comprising a comb-shaped structure connecting the magnetically inactive layers to at least one of a support structure and an additional magnetic pole.
7. The electric machine of claim 1 , wherein the magnetically inactive layers do not completely occupy a space between the magnetically active layers.
8. The electric machine of claim 1 , wherein the magnetically inactive layers are arranged flush with the magnetically active layers at the end of the first magnetic pole.
9. The electric machine of claim 1 , wherein the first magnetic pole forms a stator of the electric machine and the second magnetic pole forms a rotor of the electric machine.
10. The electric machine of claim 1 , wherein the first magnetic pole forms a rotor of the electric machine and the second magnetic pole forms a stator of the electric machine.
11. The electric machine of claim 1 , wherein the electric machine is a linear electric machine.
12. The electric machine of claim 1 , wherein the electric machine is a rotary electric machine.
13. A magnetic pole part constructed as a first magnetic pole of an electric machine, comprising:
an arrangement of layers having magnetically active layers with a total volume (V a ) and magnetically inactive layers with a total volume (V i ) which have a lower average density than the magnetically active layers, wherein the magnetically active layers and the magnetically inactive layers repeat in a specified order with a period p, and wherein a ratio (k) of the total volume (V a ) of the magnetically active layers to the combined total volume (V a +V i ) of the magnetically active layers and the magnetically inactive layers fulfills the condition 0.5≦k≦0.8.
14. A vehicle including an electric machine which comprises
a first magnetic pole comprising an arrangement of layers having magnetically active layers with a total volume (V a ) and magnetically inactive layers with a total volume (V i ) which have a lower average density than the magnetically active layers, wherein the magnetically active layers and the magnetically inactive layers repeat in a specified order with a period p, and wherein a ratio (k) of the total volume (V a ) of the magnetically active layers to the combined total volume (V a +V i ) of the magnetically active layers and the magnetically inactive layers fulfills the condition 0.5≦k≦0.8,
a second magnetic pole confronting the first magnetic pole and movable relative to the first magnetic pole, and
a gap having a length (l S ) extending between an end of the first magnetic pole and an end of the confronting second magnetic pole in a direction parallel to a magnetically active or magnetically inactive layer, and
an electrical conductor constructed as a coupling element between an electrical circuit and a magnetic circuit,
wherein at an operating time, the magnetic circuit comprises the first magnetic pole, the gap and the second magnetic pole, and is permeated by a common useful magnetic flux for electromechanical energy conversion.
15. A wind turbine including an electric machine which comprises
a first magnetic pole comprising an arrangement of layers having magnetically active layers with a total volume (V a ) and magnetically inactive layers with a total volume (V i ) which have a lower average density than the magnetically active layers, wherein the magnetically active layers and the magnetically inactive layers repeat in a specified order with a period p, and wherein a ratio (k) of the total volume (V a ) of the magnetically active layers to the combined total volume (V a +V i ) of the magnetically active layers and the magnetically inactive layers fulfills the condition 0.5≦k≦0.8,
a second magnetic pole confronting the first magnetic pole and movable relative to the first magnetic pole, and
a gap having a length (l S ) extending between an end of the first magnetic pole and an end of the confronting second magnetic pole in a direction parallel to a magnetically active or magnetically inactive layer, and
an electrical conductor constructed as a coupling element between an electrical circuit and a magnetic circuit,
wherein at an operating time, the magnetic circuit comprises the first magnetic pole, the gap and the second magnetic pole, and is permeated by a common useful magnetic flux for electromechanical energy conversion,
the wind turbine further comprising a blade that is mechanically coupled to a rotor of the electric machine.
16. A method for producing an electric machine, comprising:
forming a first magnetic pole comprising an arrangement of layers having magnetically active layers with a total volume (V a ) and magnetically inactive layers with a total volume (V i ) which have a lower average density than the magnetically active layers, wherein the magnetically active layers and the magnetically inactive layers repeat in a specified order with a period p, and wherein a ratio (k) of the total volume (V a ) of the magnetically active layers to the combined total volume (V a +V i ) of the magnetically active layers and the magnetically inactive layers fulfills the condition 0.5≦k≦0.8,
forming a second magnetic pole confronting the first magnetic pole and movable relative to the first magnetic pole, wherein gap having a length extends between an end of the first magnetic pole and an end of the confronting second magnetic pole in a direction parallel to a magnetically active or magnetically inactive layer, and
arranging an electrical conductor constructed as a coupling element between an electrical circuit and a magnetic circuit.
17. The method of claim 16 , wherein the magnetically active layers have thicknesses (b Al ) defined by:
l S /4≦ b Ai ≦l S /20,
wherein l s is the length of the gap.