Rotating electric machine

Abstract

To provide a rotating electric machine capable of suppressing flowing a magnetic flux with an asynchronous component to the rotor coil.SOLUTION: A rotating electric machine of the embodiment includes: a rotor having a field magnetic portion that generates a magnetic field; and a stator provided on the outer radial side of the rotor and having a stator coil that generates a magnetic field that interacts with the magnetic field generated by the field magnetic portion. In the rotating electric machine, the rotor includes a conductive damper provided on the inner radial side of the stator coil to face the stator coil and, the thickness of the diameter direction of the rotor at both end portions of the axial direction of the rotor of the damper is larger than the thickness of the diameter direction of the rotor at the center portion of the axial direction of the rotor of the damper.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] Embodiments of the present invention relate to a rotating electrical machine.

Background Art

[0002] With the construction of power generation systems accompanying the spread of renewable energy and the progress of electrification in various industrial fields, the application of high magnetic field rotating electrical machines (motors, generators, etc.) is being considered. In this type of rotating electrical machine, since the high magnetic field becomes the magnetic flux density in a region above the magnetic saturation of a magnetic material such as iron, the iron core is often formed of a non-magnetic material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A rotating electrical machine, for example, a motor, generates torque by synchronizing the magnetic flux due to the magnetic field of the stator coil and the magnetic flux due to the magnetic field of the rotor coil and rotating them. However, due to the arrangement of the fixed coil, the electric control device, the fluctuation of the load, etc., magnetic fluxes of components other than the synchronous component (asynchronous component) may be generated. The asynchronous component is, for example, a harmonic component that is not synchronized with the input current. When the magnetic flux of the asynchronous component enters the rotor coil, losses occur in the rotor coil. The losses cause a failure of the rotor coil.

[0005] In order to suppress the entry of such magnetic flux of the asynchronous component into the rotor coil, a conductive cylindrical damper integrated with the rotor may be installed between the rotor coil and the stator coil.

[0006] However, even if a damper is installed, if the core is made of a non-magnetic material, the magnetic flux generated at both ends (coil ends) of the stator coil cannot be induced into the core, and the magnetic flux enters particularly into both ends in the rotor shaft direction of the rotor coil. Furthermore, the higher the frequency of the magnetic flux, the smaller the shielding effect of the damper on both ends in the rotor shaft direction of the rotor coil compared to the central portion in the rotor shaft direction of the rotor coil, and it becomes easier for the magnetic flux to enter both ends in the rotor shaft direction. As a result, the asynchronous component of the magnetic flux affects the rotor coil adversely, and losses occur.

[0007] The problem to be solved by the invention is to provide a rotating electrical machine capable of suppressing the entry of the asynchronous component of the magnetic flux into the rotor coil.

Means for Solving the Problem

[0008] The rotating electrical machine according to the embodiment includes a rotor having a field part that generates a magnetic field, and a stator provided on the outer diameter side of the rotor and having a stator coil that generates a magnetic field that interacts with the magnetic field generated by the field part. In the rotating electrical machine, the rotor includes a conductive damper provided on the inner diameter side of the stator coil so as to face the stator coil, and the thickness in the rotor radial direction at both ends in the rotor shaft direction of the damper is larger than the thickness in the rotor radial direction at the central portion in the rotor shaft direction of the damper.

Effect of the Invention

[0009] According to the present invention, it is possible to suppress the entry of the asynchronous component of the magnetic flux into the rotor coil.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described with reference to the drawings.

[0012] (Overall Configuration) FIG. 1 is a diagram showing an example of the shape when the main part of the rotating electrical machine according to the embodiment is viewed in the axial direction. Further, FIG. 2 is a diagram showing an example of a partial cross-sectional shape (a cross-sectional shape parallel to the rotation axis) of the rotating electrical machine. In FIG. 2, in order to avoid complication of the illustration, the illustration of the lower half of the rotating electrical machine is omitted, and only the upper half is illustrated. In FIG. 1, CL1 indicated by a one-dot chain line represents the center (line) of the rotation axis of the rotating electrical machine. Also, CL2 indicated by a one-dot chain line represents the axial center (plane) of the rotating electrical machine.

[0013] The rotating electrical machine shown in FIGS. 1 and 2 is, for example, a high magnetic field rotating electrical machine, and includes a rotor 1 and a stator 6 provided apart from the outer diameter side of the rotor 1. Note that the stator 6 may be provided on the inner diameter side of the rotor 1, but here, an example in which the stator 6 is provided on the outer diameter side of the rotor 1 is shown.

[0014] (Configuration of Rotor 1) The rotor 1 includes a rotating shaft 2, a rotor coil (field part) 3, a rotor coil support member 4, and a damper 5.

[0015] In this embodiment, the case where a rotor coil is employed as the field means (field part) on the rotor side is exemplified, but it is also possible to employ a permanent magnet instead of the rotor coil.

[0016] The rotating shaft 2 is a shaft that rotates as the central axis of the rotor 1.

[0017] The rotor coil 3 is supported by the rotor coil support member 4 so as to be able to rotate together with the rotating shaft 2. The rotor coil 3 is wound in a shape close to a rectangular shape around the rotor coil support member 4 and functions as a field part that generates a magnetic field.

[0018] The rotor coil support member 4 is made of, for example, a magnetic material. In this case, the rotor coil support member 4 functions as a rotor pole. The rotor coil support member 4 may constitute a part of the iron core. Also, the rotor coil support member 4 may be made of a non-magnetic material (non-magnetic body). In this case, the rotor coil 3 functions as an air-core coil.

[0019] In the example of FIG. 1, the rotor coil 3 and the rotor coil support member 4 are each composed of four, and the case of forming four magnetic poles (two N poles and two S poles) is exemplified. However, it is not limited to this example, and the number of each of the rotor coil 3 and the rotor coil support member 4 may be configured to be an even number other than four (the number of magnetic poles is a number other than four).

[0020] (Configuration of Stator 6) The stator 6 includes a stator coil 7, a magnetic shield 8, and a frame 9.

[0021] The stator coil 7 generates a magnetic field that interacts with the magnetic field generated by the rotor coil (field part) 3.

[0022] The magnetic shield 8 is a magnetic material and is provided at a distance from the stator coil 7. In the examples of FIGS. 1 and 2, the magnetic shield 8 is provided at a distance on the outer diameter side of the stator coil 7. However, when the stator 6 is arranged on the inner diameter side of the rotor 1, the magnetic shield 8 is provided at a distance on the inner diameter side of the stator coil 7.

[0023] The frame 9 is formed using a metal material and is arranged so as to surround the rotor 1 and the stator 6. The frame 9 includes one cylindrical frame portion 9a, two cylindrical frame portions 9b, and two annular (ring-shaped) frame portions 9c.

[0024] When the rotating electrical machine operates as a generator, the magnetic field generated by the rotor coil 3 arranged around the rotating shaft 2 generates electric power in the fixed stator coil 7 by electromagnetic induction. When the rotating electrical machine operates as a motor, torque is generated by the interaction between the magnetic field created by the current flowing in the fixed stator coil 7, and the rotor 1 rotates.

[0025] (Damper 5) Generally, the damper suppresses the entry of the asynchronous component of the magnetic flux by the rotor coil 3 and the magnetic flux by the stator coil 7 into the rotor coil 3. By making the damper 5 of the present embodiment have a structure in which both end portions in the rotor axis direction are thicker in the rotor diameter direction than the central portion in the rotor axis direction, the effect of reducing the magnetic flux of the asynchronous component entering the rotor coil 3 is enhanced particularly at both end portions in the rotor axis direction of the damper 5.

[0026] The damper 5 is a member having conductivity and non-magnetism and functions as a magnetic damper. This damper 5 is provided on the inner diameter side of the stator coil 7 so as to face the stator coil 7. Specifically, it is disposed in the space between the inner diameter side of the stator coil 7 and the outer diameter side of the rotor coil support member 4, and is disposed so as to face the stator coil 7 and the surface of the rotor coil support member 4. Further, the damper 5 is stably attached to a predetermined member on the rotor 1 side via a support mechanism (not shown) so as to rotate in synchronization with the rotor 1.

[0027] Here, an example in the case where the damper 5 is composed of a single member is shown, but as will be described later, the damper 5 may be configured as being composed of a plurality of members.

[0028] The damper 5 has a cylindrical portion and annular portions respectively disposed at both axial ends of the cylindrical portion. The annular portions have a structure that protrudes convexly toward the stator side from both axial ends of the cylindrical portion, specifically, a structure that extends so as to approach both axial ends of the stator coil 7 in the stator axial direction.

[0029] (Dimensional information of each part) FIG. 3 shows the dimensional information of each part in the rotating electrical machine according to the embodiment. The dimensional information includes D1, D2, D3, D4, D5, D6, and D7. However, in FIG. 3, for the sake of easy understanding of the configuration, some of the dimensions of the illustrated parts are made larger or smaller than the actual ones. Therefore, the size relationship of the dimensions of the illustrated parts may be different from the actual ones.

[0030] D1 represents the thickness in the rotor radial direction at the center in the rotor axial direction of the damper 5 (that is, the thickness in the rotor radial direction in the cylindrical portion of the damper 5).

[0031] D2 represents the thickness in the rotor radial direction at both axial ends in the rotor axial direction of the damper 5 (that is, the thickness in the rotor radial direction in the annular portion).

[0032] D3 represents the axial distance from the axial center CL2 of the rotating electrical machine to the rotor axial ends (both ends) of the damper 5.

[0033] D4 represents the axial distance from the axial center CL2 of the rotating electrical machine to the rotor axial ends (both ends) of the rotor coil support member 4.

[0034] D5 represents the axial distance from the axial center CL2 of the rotating electrical machine to the rotor axial ends (both ends) of the rotor coil 3.

[0035] In this embodiment, the thickness D2 of the damper 5 is configured to be greater than the thickness D1 of the damper 5. By configuring it in this way, particularly at both ends of the damper 5 in the rotor axial direction, the region that intersects with the magnetic flux generated from the stator axial ends of the stator coil 7 expands, the magnetic flux suppression effect is large, and the asynchronous component magnetic flux that enters the range rotor coil 3 can be effectively suppressed.

[0036] Also, in this embodiment, the thickness D7 of the damper 5 is configured to be equal to or greater than the thickness D1 of the damper 5. Further, the dimension D3 of the damper 5 is configured to be greater than the dimensions D4 and D5. By configuring it in this way, since the damper 5 shields the magnetic flux in a thicker and wider region, the suppression effect of the asynchronous component magnetic flux that enters the rotor coil 3 can be further enhanced.

[0037] (Function of the damper 5) FIG. 4 schematically shows the relationship between the damper 5 and the magnetic flux in this embodiment. FIG. 4 is a diagram in which the magnetic flux is drawn in FIG. 2.

[0038] Figure 4 schematically shows the magnetic flux H1 generated between the rotor 1 and the stator 6 near the axial center CL2 of the rotating electrical machine, and the magnetic flux H2 generated from the axial ends of the stator coil 7 in the stator axial direction. Note that for the magnetic flux H2, only the magnetic flux generated from the left end in Fig. 4 is shown out of the magnetic fluxes generated from both axial ends of the stator coil 7 in the stator axial direction. Also, although not shown in Fig. 4, the magnetic fluxes H1 and H2 each contain both a synchronous component magnetic flux and an asynchronous component magnetic flux.

[0039] The magnetic flux H1 forms a flow as shown in Fig. 4 for each magnetic pole. That is, the magnetic flux H1, for example, goes in the depth direction of the paper surface on the stator 6 side, then goes from the stator 6 side to the rotor 1 side, then goes in the front direction of the paper surface on the rotor 1 side, then goes from the rotor 1 side to the stator 6 side, and again goes in the depth direction of the paper surface on the stator 6 side, forming such a flow.

[0040] The magnetic flux H2 forms a flow as shown in Fig. 4 for each magnetic pole. That is, the magnetic flux H2 forms a flow that draws a plurality of ellipses centered on the axial end of the stator coil 7 in the stator axial direction. Among the magnetic fluxes H2 shown in Fig. 4, there are those that draw small ellipses (magnetic fluxes that do not reach the damper 5), those that draw large ellipses (magnetic fluxes that exceed the damper 5 and reach the axial end of the rotor coil 3 in the rotor axial direction), and those that draw ellipses of about the middle size (magnetic fluxes that do not reach the axial end of the rotor coil 3 in the rotor axial direction but reach the axial end of the rotor coil support member 4 in the rotor axial direction), etc., with various sizes.

[0041] The damper 5 of the present embodiment has not only a cylindrical portion but also annular portions disposed at both axial ends of the cylindrical portion. Therefore, much of the magnetic flux H2 shown in FIG. 4 links with the damper 5. That is, the damper 5 of the present embodiment has a wide region that links with the magnetic flux generated from the axial end of the stator coil 7 in the stator axial direction. For example, the magnetic flux H2 links with the surface R1 of the cylindrical portion of the damper 5 and also links with the surface R2 of the annular portion of the damper 5. The magnetic flux linking with the damper 5 is reduced by the eddy current generated on the surface of the damper 5 by the magnetic flux. Along with this, the magnetic flux of the asynchronous component included in the magnetic flux is also reduced.

[0042] As described above, the damper 5 of the present embodiment has a wide region that links with the magnetic flux generated from the axial end of the stator coil 7 in the stator axial direction, particularly at both axial ends of the damper 5 in the rotor axial direction, and a wide surface where eddy current is generated. Therefore, the magnetic flux suppression effect is large, and the magnetic flux of the asynchronous component entering the range rotor coil 3 can be effectively suppressed.

[0043] (Operation of Conventional Damper) FIG. 5 schematically shows the relationship between a conventional damper 5' and magnetic flux.

[0044] In FIG. 5, similar to FIG. 4, the magnetic flux H1 generated between the rotor 1 and the stator 6 near the axial center CL2 of the rotating electrical machine and the magnetic flux H2 generated from the axial end of the stator coil 7 in the stator axial direction are schematically represented.

[0045] The conventional damper 5' has a cylindrical portion but does not have the above-described annular portion. Therefore, the conventional damper 5' has a smaller region that links with the magnetic flux H2 generated from the axial end of the stator coil 7 in the stator axial direction than the damper 5 of the present embodiment, a narrower surface where eddy current is generated, and there is a lot of magnetic flux that cannot be completely suppressed.

[0046] Thus, in the conventional damper 5', the area where the magnetic flux H2 generated from the axial end of the stator coil 7 intersects is small, the surface where eddy currents are generated is narrow, and there is a large amount of magnetic flux that cannot be suppressed. Therefore, the asynchronous component of the magnetic flux entering the rotor coil 3 cannot be effectively suppressed.

[0047] (Verification of Effects) The results of verifying the difference between the effects of the damper 5 of this embodiment and the effects of the conventional damper 5' will be described using examples of two graphs.

[0048] Here, points A and B are set as the observation points of the magnetic flux. In both FIGS. 4 and 5, point A is provided on the outer diameter side surface at the axial center of the rotor coil support member 4, and point B is provided on the outer diameter side surface at the axial end of the rotor coil support member 4.

[0049] FIG. 6 is a graph showing the magnetic flux density distribution at points A and B when the damper 5 of this embodiment and the conventional damper 5' are each formed of a material with high conductivity. FIG. 7 is a graph showing the magnetic flux density distribution at points A and B when the damper 5 of this embodiment and the conventional damper 5' are each formed of a material with lower conductivity than in the case of FIG. 6.

[0050] Both graphs in FIGS. 6 and 7 show the results obtained by numerically analyzing the magnetic flux density observed at points A and B for each of the damper 5 of this embodiment and the conventional damper 5'. In each graph, the horizontal axis represents the frequency of the magnetic flux, and the vertical axis represents the magnetic flux density. The magnetic flux density on the vertical axis represents the p.u. value when the magnetic flux density without a damper is set to 1, and both the horizontal axis and the vertical axis are represented logarithmically.

[0051] P1 and P2 shown in each graph represent the magnetic flux density observed at points A and B, respectively, when the conventional damper 5' is used, and E1 and E2 represent the magnetic flux density observed at points A and B, respectively, when the damper 5 of this embodiment is used.

[0052] From the graph of FIG. 6, at point A, it can be seen that the magnetic flux density P1 when using the conventional damper 5' and the magnetic flux density E1 when using the damper 5 of the present embodiment are equally small compared to the case without a damper. On the other hand, at point B, it can be seen that the magnetic flux density E2 when using the damper 5 of the present embodiment is smaller than the magnetic flux density P2 when using the conventional damper 5'. Also, it can be seen that the higher the frequency, the higher the reduction effect of the magnetic flux density E2 when using the damper 5 of the present embodiment.

[0053] From the graph of FIG. 7, similar to the graph of FIG. 6, at point A, it can be seen that the magnetic flux density P1 when using the conventional damper 5' and the magnetic flux density E1 when using the damper 5 of the present embodiment are equally small compared to the case without a damper. The magnetic flux densities P1 and E1 shown in the graph of FIG. 7 are smaller than the magnetic flux densities P1 and E1 shown in the graph of FIG. 6. At point B, similar to the graph of FIG. 6, it can be seen that the magnetic flux density E2 when using the damper 5 of the present embodiment is smaller than the magnetic flux density P2 when using the conventional damper 5'. Also, it can be seen that the higher the frequency, the higher the reduction effect of the magnetic flux density E2 when using the damper 5 of the present embodiment.

[0054] Thus, it can be seen that in both the case of using a material with high conductivity and the case of using a material with low conductivity, the damper 5 of the present embodiment has a large effect of suppressing magnetic flux, particularly at both ends in the rotor shaft direction. That is, it can be seen that the effect of suppressing the entry of the magnetic flux of the asynchronous component into the rotor coil 3 is large.

[0055] (Modification example) Next, a modification example of the damper 5 of the present embodiment will be described.

[0056] FIG. 8 is a diagram showing an example of a cross-sectional shape (the shape of a cross-section perpendicular to the rotation axis) of a part of a rotating electrical machine showing a modification example of the damper 5 of the present embodiment.

[0057] In FIG. 2 described above, an example in which the damper 5 is composed of a single member was shown. However, the damper 5 shown in FIG. 8 is composed of a plurality of members (damper members). Specifically, the damper 5 shown in FIG. 8 is composed of a cylindrical member 5a and annular members 5b respectively attached to both axial ends of the cylindrical member 5a.

[0058] That is, the damper 5 shown in FIG. 8 is formed by attaching annular members 5b to both ends in the rotor axis direction of a cylindrical member 5a having a shape equivalent to that of a general damper. The attachment of the member 5b to the member 5a is realized by a fixture such as a bolt, adhesion, welding, or shrink fitting.

[0059] By making the damper 5 composed of a plurality of members (damper members) in this way, it becomes possible to improve the workability when installing the damper 5 in the manufacturing process of the rotating electrical machine. For example, when the gap between the rotor 1 and the stator 6 is narrow and it is difficult to install the damper 5 composed of a single member (such as when the annular part has difficulty passing through the gap), by adopting the damper 5 shown in FIG. 8, first installing the cylindrical member 5a and then attaching the annular member 5b, the installation of the damper 5 becomes easy.

[0060] Also, by attaching the annular member 5b to the conventional damper installed in the existing rotating electrical machine, it is possible to realize the same as the damper 5 shown in FIG. 8.

[0061] As described in detail above, according to the embodiment, it becomes possible to suppress the entry of the asynchronous component magnetic flux into the rotor coil.

[0062] Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

Description of Reference Numerals

[0063] 1... Rotor, 2... Rotating shaft, 3... Rotor coil, 4... Rotor coil support member, 5... Damper, 5a, 5b... Members (damper members), 6... Stator, 7... Stator coil, 8... Magnetic shield, 9... Frame.

Claims

1. A rotor having a field portion that generates a magnetic field, A stator provided on the outer diameter side of the rotor and having a stator coil that generates a magnetic field that interacts with the magnetic field generated by the field portion, In a rotating electrical machine comprising: The rotor is Provided with a conductive damper provided on the inner diameter side of the stator coil so as to face the stator coil, The thickness in the rotor radial direction at both ends in the rotor axial direction of the damper is larger than the thickness in the rotor radial direction at the center in the rotor axial direction of the damper, Rotating electrical machine.

2. The damper has a cylindrical portion and annular portions respectively disposed at both axial ends of the cylindrical portion, The rotating electrical machine according to claim 1.

3. The annular portion has a structure that protrudes from both axial ends of the cylindrical portion toward the stator side, The rotating electrical machine according to claim 2.

4. The thickness in the rotor axial direction at both ends in the rotor axial direction of the damper is equal to or greater than the thickness in the rotor radial direction at the center in the rotor axial direction, The rotating electrical machine according to claim 1.

5. The damper is composed of a cylindrical member and annular members respectively attached to both axial ends of the cylindrical member, The rotating electrical machine according to claim 1.

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