Stator for a Generator and a Flux Switching Machine for a Wind Turbine

Abstract

A stator for a generator of a wind turbine is provided. The stator comprises a magnetic frame, magnets, and magnetic sections spaced from each other. The magnets are used to fasten the magnetic sections to the frame. Further, a flux switching machine for a wind turbine, in particular a generator for a wind turbine, is provided. The flux switching machine comprises a rotor and a stator.

Claims

1. A stator for a generator of a wind turbine, the stator comprising: ferromagnetic frame magnets; and magnetic sections spaced from each other wherein the ferromagnetic frame magnets are used to fasten the magnetic sections to a frame.

2. The stator according to claim 1, wherein each magnetic section has at least a C-shaped contour facing radially inwardly and comprises a base and two arms.

3. The stator according to claim 1, wherein the frame comprises a support ring and fixing bars extending radially inwardly from the support ring.

4. The stator according to claim 3, wherein the frame comprises recesses each formed between two neighboring fixing bars.

5. The stator according to claim 3, wherein at least one of the ferromagnetic frame magnets is provided between one of two arms of one magnetic section and one of the fixing bars.

6. The stator according to claim 1, wherein a gap is provided between each magnetic section and the frame, which gap can be filled by a material and/or used for cooling.

7. The stator according to claim 1, wherein each magnetic section is provided with at least one ferromagnetic frame magnet on two face sides of the magnetic section, and wherein the magnetic section and the at least two magnets form a segment, in particular a preassembled segment.

8. The stator according to claim 7, wherein the magnets of one segment have an opposite magnetic orientation.

9. The stator according to claim 7, wherein the magnets of neighbored segments have the same magnetic orientation.

10. The stator according to claim 1, wherein the magnetic sections are -shaped such that two central legs and an intermediate slit are provided.

11. The stator according to claim 10, wherein an additional magnet, in particular a permanent magnet, is provided within the slit.

12. The stator according to claim 11, wherein the additional magnet has an opposite magnetic orientation with respect to the ferromagnetic frame magnets used to fasten the magnetic sections.

13. The stator according to claim 1, wherein the magnetic sections are circumferentially spaced.

14. The stator according to claim 2, wherein at least one winding is provided, in particular at least one concentrated winding between both arms of each magnetic section and/or that the magnetic sections are made of iron or by a lamination stack.

15. A flux switching machine for a wind turbine, in particular a generator for a wind turbine, comprising: a rotor; and a stator comprising ferromagnetic frame magnets, and magnetic sections spaced from each other wherein the ferromagnetic frame magnets are used to fasten the magnetic sections to a frame.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Further features and advantages of the invention will become apparent from the following description and from the accompanying drawings to which reference is made. In the drawings:

[0031] FIG. 1 is a schematic overview of a flux switching machine according to the invention,

[0032] FIG. 2 is a detail view of a stator according to the invention having segments according to a first embodiment,

[0033] FIG. 3 a perspective view of a segment according to a second embodiment which can be used by a stator according to the invention,

[0034] FIG. 4 shows the segment of FIG. 3 in an exploded view,

[0035] FIG. 5 is a perspective view of a detail of a stator according to the invention having segments according to the second embodiment, and

[0036] FIG. 6 is a schematic view of one segment according to a third embodiment.

DETAILED DESCRIPTION

[0037] FIG. 1 shows a schematic overview of a flux switching machine 10, in particular a generator, for a wind turbine.

[0038] The flux switching machine 10 comprises a rotor 12 having rotor teeth 14. The rotor teeth 14 are provided on an outer circumference of the rotor 12.

[0039] Further, the flux switching machine 10 comprises a stator 16 which surrounds the rotor 12 such that rotor teeth 14 are facing the stationary stator 16.

[0040] The stator 16 comprises a ferromagnetic frame 18 which is formed by an outer support ring 20 and fixing bars 22 extending radially inwardly from an inner surface of the support ring 20. Hence, the fixing bars 22 are orientated to a center of the support ring 20.

[0041] The fixing bars 22 are further formed such that they are tapered radially inwardly. Hence, the fixing bars 22 can be considered as sharp teeth.

[0042] In general, the support ring 20 and the fixing bars 22 are formed integrally.

[0043] Recesses 24 are provided between adjacent fixing bars 22, which are formed like ring segments (please see FIG. 2). These recesses 24 are used for receiving segments 26 wherein each recess 24 receives one segment 26.

[0044] In this embodiment, each segment 26 is formed by a substantially C-shaped magnetic section 28 which has a base 30 and two arms 32 protruding substantially vertical from the base 30 in a radial inward direction. The arms 32 are arranged at the outer edges of the base 30 such that they form a C-shaped contour. The term C-shaped refers to a cross-sectional view (two dimensional) of the magnetic section, while the magnetic section 28 is of course three dimensional.

[0045] The arms 32 have two face sides 34 facing in circumferential direction wherein each face side 34 is provided with a magnet 36 such that the magnetic section 28 is surrounded laterally by two magnets 36. The magnets 36 can be glued to the face sides 34. In this embodiment, the magnets 36 are formed as permanent magnets.

[0046] The magnetic sections 28 can be made of iron or a lamination stack.

[0047] Further, each segment 26 provides a winding 38. The windings 38 are formed as concentrated windings which are inserted between the inner sides of the arms 32 such that a compact design of the segments 26 is achieved.

[0048] Each segment 26 is inserted into one recess 24 of the frame 18 such that the permanent magnets 36 each abut a corresponding fixing bar 22. Due to the shape of the fixing bars 22, a radial stop for the segments 26 is provided ensuring that the position of the segments 26 are maintained, in particular the position of the magnetic sections 28, the permanent magnets 36, and the windings 38.

[0049] Since the frame 18 is made of a magnetic material, the permanent magnets 36 interact with the frame 18, in particular the fixing bars 22, as well as with the magnetic sections 28. Hence, the magnetic sections 28 are fixed to the frame 18 by the permanent magnets 36.

[0050] Therefore, the permanent magnets 36 of one magnetic section 28 are oriented such that they have an opposite magnetic orientation wherein adjacent permanent magnets 36 of neighbored segments 26 have the same magnetic orientation. This ensures a better fixation as adjacent permanent magnets 36 of neighbored sections 28 interact with each other establishing an attracting force between them.

[0051] This is illustrated by arrows M in FIG. 1 which represent the magnetic flux direction of the magnets 36 as well as the flux concentration (dashed arrow) of a magnetic section 28.

[0052] Further, a gap 40 is present between each inserted segment 26 and the support ring 20 as the gap 40 is formed between the base 30 and the support ring 20. These gaps 40 ensure that no direct contact is provided between one of the magnetic sections 28 and the outer support ring 20 encircling the magnetic sections 28.

[0053] The permanent magnets 36 can be disposed on the face sides 34 in a full faced manner such that each gap 40 extends between two adjacent fixing bars 22 ensuring that no direct contact is provided between one of the permanent magnets 36 and the support ring 20.

[0054] In the embodiment shown in FIG. 1, the stator 16 comprises twelve recesses 24 and twelve segments 26 inserted into these recesses 24.

[0055] Due to the formation of the recesses 24, the segments 26 and in particular the permanent magnets 36, the magnetic sections 28 as well as the windings 38 are all circumferentially disposed. Furthermore, the segments 26 are circumferentially spaced as the fixing bars 22 separate the segments 26 from each other.

[0056] As can be seen in FIG. 1, the inner circumferential face surface 42 of each segment 26 can have a round shape such that all segments 26 and the fixing bars 22 form a continuous surface which faces radial inwardly to the rotor 12 and its rotor teeth 14.

[0057] In FIGS. 3 to 5, a second embodiment of the segment 26 is shown wherein the C-shaped magnetic section 28 is modified. The magnetic section 28 according to the second embodiment has a -shape as two central legs 44 and an intermediate slit 46 are formed. The term -shape (or EURO sign-shaped) relates to a cross-sectional view of the magnetic section 28, while the magnetic section 28 is of course three dimensional. The two central legs 44 are oriented parallel and project to the inner area of the -shaped magnetic section 28 which also comprises a C-shaped main part 45 beside the two central legs 44. Both central legs 44 are arranged at the same distance from a center point 47 (or rather central line 47) of the C-shaped or C-curved main part 45 wherein they are orientated mainly perpendicular to the tangent in the center point 47 of the main part 45. The center point 47 refers to a two dimensional cross-sectional view of the -shaped magnetic section 28, while line 47 is rather a center line from a three dimensional perspective which extends along the body of the magnetic section 28, in particular the main part 45, as illustrated by the dashed line in FIGS. 3 and 4.

[0058] Further, a magnet 48 is inserted into the slit 46 which can have the same magnetic strength as the other permanent magnets 36 disposed on the face sides 34 of the magnetic section 28. The magnet 48 can also be a permanent magnet.

[0059] However, the orientation of the magnet 48 can be opposite to the permanent magnets 36 such that the relationship regarding the magnetic orientation is 2:1 since two permanent magnets 36 on the face sides 34 and one magnet 48 having an opposite magnetic orientation are provided.

[0060] As shown in FIG. 4, the winding 38 has a clearance 50 in its middle portion for receiving the central legs 44 and the magnet 48 when inserted into the magnetic section 28. Hence, a compact design of the segments 26 is provided.

[0061] In FIG. 5, a perspective view of the stator 16 comprising the segments 26 of the second embodiment is shown.

[0062] The radial inwardly tapered fixing bars 22 as well as the circular circumferential face surface 42 become obvious. Further, the gaps 40 are shown which can be filled by a material such as iron or copper in order to provide a hybrid excitable flux switching machine 10 or for cooling purposes.

[0063] As the magnetic sections 28 are fixed to the frame 18 by the permanent magnets 36, no fixing holes are required within the frame 18.

[0064] In general, the phase difference of the flux switching machine 10 is managed by the combination of the stator segments 26 and the number of the rotor teeth 14.

[0065] A stator 16 as well as a flux switching machine 10 is provided which reduce the leakage flux and, therefore, improve the efficiency.

[0066] In FIG. 6, a third embodiment of a segment section 26 is shown which comprises a base 30 and two arms 32 carrying windings 52.

[0067] In contrast to the C-shaped magnetic sections 28 shown in the previous embodiments, the arms 32 are not provided at the outer edges of the base 30 to which the magnets 36 are attached.

[0068] However, this segment 26 also has a C-shaped contour 54 which is formed between the arms 32 and the portion of the base 30 located between the arms 32, in particular between the surfaces of the arms 32 facing each other.

[0069] The C-shaped contour 54 faces radial inwardly when the segment 26 is attached to the frame which is not shown in this Figure.

[0070] Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. For that reason, the following claims should be studied to determine the true scope and content of this disclosure.