Rotating electric machine

Abstract

Provided is a rotating electric machine capable of reducing eddy current loss and hysteresis loss generated at a part where an electromagnetic steel sheet is fastened.　In the rotating electric machine comprising a stator and a rotator provided inside the stator, the stator has a stator core, a stator slot disposed in the circumferential direction of the stator core, and a stator winding disposed in the stator slot, and the rotor has a central shaft, a rotor slot, and a rotor conductor. The stator has a low-resistance fastening member on the outer periphery of the stator core, and the low-resistance fastening member has a fastening part provided outside the stator and a stator conductor provided inside the stator, wherein electric resistance of the fastening part is smaller than electric resistance of the stator conductor.

Description

rotating electrical machines

[0001] The present invention relates to a rotating electric machine.

[0002] A rotating electric machine is known in which a plurality of electromagnetic steel sheets are stacked in the axial direction and fastened together. For example, a rotating electric machine described in Patent Document 1 is configured with two clampers that sandwich the axially stacked electromagnetic steel sheets from both axially outer sides, and a plurality of clamping rods that fasten the two clampers from both axially outer sides.

[0003] JP 2023-5315 A

[0004] The rotating electric machine of Patent Document 1 has a clamper with a sufficient thickness to ensure sufficient rigidity. However, when the clamper and the clamping rod are interlinked with magnetic flux due to the rotating magnetic field, eddy current loss and hysteresis loss occur. However, no measures to reduce these losses have been considered.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a rotating electrical machine capable of reducing eddy current loss and hysteresis loss that occur in the portions where the electromagnetic steel sheets are fastened.

[0006] An example of the solution in the present invention is as follows.

[0007] A rotating electric machine having a stator and a rotor provided inside the stator, the stator having a stator core, stator slots arranged circumferentially around the stator core, and stator windings arranged in the stator slots, the rotor having a central shaft, rotor slots, and rotor conductors, wherein the stator has low-resistance fastening members on the outer periphery of the stator core, and the low-resistance fastening members have fastening portions arranged on the outside of the stator and stator conductors arranged inside the fastening portions, and the electrical resistance of the stator conductors is lower than the electrical resistance of the fastening portions.

[0008] According to the present invention, it is possible to reduce eddy current loss and hysteresis loss that occur in the portion where the electromagnetic steel sheets are fastened, and to improve the efficiency of the rotating electric machine.

[0009] Further means and advantages of the present invention will become apparent throughout the entire specification below.

[0010] 6A . A cross-sectional view taken along line B-B of FIG. 2 , showing a main portion of a rotating electric machine. An enlarged view of part EX1 of FIG. 1A. A cross-sectional view taken along line A-A of FIG. 1 , showing a main portion of a rotating electric machine. An enlarged view of part EX2 of FIG. 2A. A cross-sectional view taken along line C-C of FIG. 2 , showing the axial outside of a rotating electric machine. A diagram explaining the principle by which a magnetic field due to eddy currents in a stator conductor cancels out magnetic flux linking at a fastening portion. A cross-sectional view showing a main portion of a rotating electric machine. An enlarged view of part EX3 of FIG. 5A. A cross-sectional view taken along line E-E of FIG. 7 , showing a main portion of a rotating electric machine. An enlarged view of part EX4 of FIG. 6A. A cross-sectional view taken along line D-D of FIG. 6 , showing a main portion of a rotating electric machine. An enlarged view of part EX5 of FIG. 7A. A cross-sectional view taken along line G-G of FIG. 9 , showing a main portion of a rotating electric machine. An enlarged view of part EX6 of FIG. 8A. A cross-sectional view taken along line F-F of FIG. 8 , showing a main portion of a rotating electric machine. An enlarged view of part EX7 of FIG. 9A. An enlarged view of part EX7 of FIG. 9A , shown at a position shifted from FIG. 9B.

[0011] Examples will be described below with reference to the drawings. Each example will focus on a stator structure that can reduce eddy current loss and hysteresis loss that occur in the portions where the magnetic steel sheets are fastened, which is a feature of the present invention.

[0012] As an example of a rotating electrical machine, a squirrel-cage induction motor will be used for explanation.

[0013] Fig. 1A is a cross-sectional view taken along line BB in Fig. 2A. Meanwhile, Fig. 2A corresponds to a cross-sectional view taken along line AA in Fig. 1A. Fig. 1B is an enlarged view of part EX1 in Fig. 1A, and Fig. 2B is an enlarged view of part EX2 in Fig. 2A.

[0014] FIG. 3 is a cross-sectional view taken along the line CC in FIG. 2A, and corresponds to an end of the rotating electrical machine.

[0015] The stator 1 and rotor 5 face each other in the radial direction across a gap 12. The stator 1 includes a stator core 2 and a stator winding 4 wound in stator slots 3 formed in the stator core 2. The rotor 5 includes a rotor core 6, rotor slots 7 formed in the rotor core 6, rotor conductors 8 arranged in the rotor slots 7, rotor short-circuit rings 11 that sandwich the rotor conductors 8 from both axial outsides, and a shaft 9 arranged on the inner circumferential side of the rotor core 6.

[0016] In the stator 1, a plurality of electromagnetic steel sheets are laminated and fastened in the axial direction to form the stator core 2. In this embodiment, as shown in Figures 1A, 2A, and 3, the stator 1 has low-resistance fastening members 10 on its outer periphery.

[0017] The characteristics of the low-resistance fastening member 10 will be explained with reference to the enlarged views of Figures 1B and 2B. The low-resistance fastening member 10 of this embodiment has a fastening portion 10A. The fastening portion 10A is electrically conductive in the axial direction. When viewed in the radial direction of the electromagnetic steel sheet, a stator conductor 10B is located between the stator winding 4 and the fastening portion 10A, and is electrically conductive in the axial direction. The fastening portion 10A may also be considered a fastening member.

[0018] Then, by making the resistivity of the stator conductor 10B lower than that of the fastening portion 10A, a low-resistance fastening member 10 is realized. In this way, the fastening portion 10A, which is responsible for maintaining strength, and the stator conductor 10B, which is responsible for reducing resistance, share the functions of the fastening portion 10A, which is responsible for maintaining strength, and the stator conductor 10B, which is responsible for reducing resistance, thereby forming a low-resistance fastening member 10 that achieves both strength and low resistance.

[0019] Next, the principle by which this configuration can reduce eddy current loss and hysteresis loss that occur in the portion where the electromagnetic steel sheets are fastened will be described with reference to FIG.

[0020] 4 is a diagram illustrating the principle by which magnetic flux due to eddy currents in the stator conductors cancels out magnetic flux linking the fastening portion. The circled x indicates the eddy current of 10B, the solid arrow indicates the flow of magnetic flux due to the excitation current of the stator winding 4, and the dashed arrow indicates the flow of magnetic flux due to the eddy current of the stator conductor 10B. At the fastening portion 10A, the solid arrow and the dashed arrow, which are in opposite directions, overlap, i.e., cancel each other out.

[0021] In order to cause this cancellation, it is necessary to make the electrical resistance of the stator conductor 10B lower than that of the fastening portion 10A.

[0022] According to Faraday's law, an induced electromotive force is generated in the stator conductor 10B in a direction that cancels out the change in magnetic flux due to the excitation current of the stator winding 4. This induced electromotive force causes magnetic flux due to eddy currents generated in the stator conductor 10B to cancel out the magnetic flux due to the excitation current of the stator winding 4, reducing the magnetic flux linking the fastening portion 10A. This reduces eddy current loss and hysteresis loss generated in the fastening portion 10A.

[0023] As described above, according to this embodiment, it is possible to realize a rotating electrical machine in which eddy current loss and hysteresis loss occurring in the portions where the electromagnetic steel sheets are fastened are reduced.

[0024] The difference between this embodiment and the first embodiment will be described with reference to FIG. 2B.

[0025] The difference between this embodiment and the first embodiment is that a stator short-circuit ring 10c is provided that short-circuits adjacent low-resistance fastening members 10 or adjacent stator conductors 10B. As a result, for example, in FIG. 1A, adjacent low-resistance fastening members can be electrically connected by the stator short-circuit ring 10C. As a result, adjacent stator conductors 10B are short-circuited by the stator short-circuit ring 10C. This also means that at least one of the adjacent low-resistance fastening members is short-circuited in the radial direction of the rotating electric machine by the stator short-circuit ring 10C.

[0026] The eddy currents generated in the stator conductors 10B are increased by providing stator short-circuit rings 10C that short-circuit multiple stator conductors 10B on both axial outer sides of the stator core 2. This is because the direction of the induced electromotive force generated in the stator conductor 10B is unidirectional when considering only one stator conductor 10B, so when the stator short-circuit rings 10C are provided, the induced electromotive force is short-circuited with other stator conductors 10B that generate eddy currents in the opposite direction, reducing electrical resistance and increasing eddy currents.

[0027] When the eddy current increases, it is possible to cancel more of the magnetic flux due to the excitation current of the stator winding 4. This further reduces the magnetic flux linking the fastening portion 10A, making it possible to further reduce the eddy current loss and hysteresis loss generated in the fastening portion 10A compared to the first embodiment.

[0028] In this case, too, in order to cause the cancellation to occur at the fastened portion 10A, it is necessary to make the electrical resistance of the stator short-circuit ring 10C lower than that of the fastened portion 10A.

[0029] By providing the stator short-circuit ring 10C, the electrical resistance becomes sufficiently lower than the reactance. Therefore, the magnitude of the eddy current is determined by the reactance. The loss due to the eddy current generated in the stator conductor 10B and the stator short-circuit ring 10C becomes proportional to the resistivity. Therefore, by using a material with a low resistivity among conductors, such as copper, aluminum, or brass, for the stator conductor 10B and the stator short-circuit ring 10C, it is possible to suppress the eddy current loss generated in the stator conductor 10B and the stator short-circuit ring 10C.

[0030] As described above, in this embodiment, the effect of reducing eddy current loss and hysteresis loss in the first embodiment can be further improved.

[0031] Furthermore, to further improve the effect, it is more desirable that the stator short-circuit rings 10C be disposed between adjacent low-resistance fastening members 10 or between adjacent stator conductors 10B.

[0032] Furthermore, to further improve the effect, it is more desirable to install the stator short-circuit rings 10C on both sides or both ends in the axial direction of the low resistance fastening member 10.

[0033] This embodiment is basically the same as embodiment 1 or embodiment 2. Therefore, the following description will focus on the differences from embodiment 1 and embodiment 2.

[0034] Fig. 5A is a view corresponding to Fig. 1A, and Fig. 5B is a view corresponding to Fig. 1B. Fig. 5B is an enlarged view of part EX3 in Fig. 5A.

[0035] The rotating electrical machine of this embodiment is characterized by having a housing 13 .

[0036] The housing 13 is disposed radially outside the stator 1 and fixes the stator 1. At least one of the housing 13 and the fastening portion 10A is made of a magnetic material.

[0037] When the housing 13 is made of a magnetic material, regardless of whether the fastening portion 10A is made of a magnetic material or a non-magnetic material, Faraday's law causes an induced electromotive force to be generated in the stator conductor 10B in a direction that cancels out the change in magnetic flux due to the excitation current of the stator winding 4. This induced electromotive force causes the magnetic flux due to eddy currents generated in the stator conductor 10B to cancel out the magnetic flux due to the excitation current of the stator winding 4, reducing the magnetic flux linking the fastening portion 10A and the housing 13. This reduces eddy current loss and hysteresis loss generated in the fastening portion 10A and the housing 13.

[0038] If the housing 13 is non-magnetic and the fastening portion 10A is magnetic, then according to Faraday's law, an induced electromotive force is generated in the stator conductor 10B in a direction that cancels out the change in magnetic flux caused by the excitation current of the stator winding 4. The magnetic flux caused by eddy currents generated in the stator conductor 10B by this induced electromotive force cancels out the magnetic flux caused by the excitation current of the stator winding 4, reducing the magnetic flux linking the fastening portion 10A. This reduces eddy current loss and hysteresis loss generated in the fastening portion 10A.

[0039] If both the housing 13 and the fastening portion 10A were made of non-magnetic material, almost no induced electromotive force would be generated in the stator conductor 10B, and the effect of reducing eddy current loss generated in the fastening portion 10A and the housing 13 would be almost non-existent.

[0040] In this embodiment, in addition to the effects of the first or second embodiment, it is possible to further reduce eddy current loss and hysteresis loss.

[0041] The differences between this embodiment and embodiment 3 will be described. Fig. 6A is a view corresponding to Fig. 5A, Fig. 6B is a view corresponding to Fig. 5B, and is an enlarged view of EX4 in Fig. 6A. Furthermore, Fig. 6A is a cross-sectional view taken along line E-E in Fig. 7A. Meanwhile, Fig. 7A is a cross-sectional view taken along line D-D in Fig. 6A. Note that Fig. 7A also corresponds to Fig. 2A, and Fig. 7B also corresponds to Fig. 2B.

[0042] This embodiment differs from the first to third embodiments in that the functions of the fastening portion 10A and the stator conductor 10B in the first embodiment are combined to form a fastening stator conductor 10D.

[0043] In this embodiment, the mutual cancellation at the fastening portion 10A in the first and second embodiments can be substituted by the housing 13. For this reason, it is desirable that the housing 13 be made of a magnetic material.

[0044] This embodiment also has the effect of reducing eddy current loss and hysteresis loss.

[0045] The difference between this embodiment and embodiment 4 is that the fastening stator conductor 10D is made of brass, which is one of the strongest conductors. This makes it possible to fasten the electromagnetic steel sheets using the fastening stator conductor 10D, and the fastening stator conductor 10D can achieve a structure that is integrated with the fastening portion.

[0046] The difference between this embodiment and the fourth embodiment is that the fastening stator conductor 10D has a lower resistance than the housing 13.

[0047] This can further improve the effect of reducing eddy current loss and hysteresis loss.

[0048] The differences between this embodiment and embodiment 4 will be described. Fig. 8A is a view corresponding to Fig. 6A, Fig. 8B is a view corresponding to Fig. 6B, and is an enlarged view of EX6 in Fig. 8A. Furthermore, Fig. 8A is a cross-sectional view taken along G-G in Fig. 9A. On the other hand, Fig. 9A is a cross-sectional view taken along F-F in Fig. 8A. Note that Fig. 9A also corresponds to Fig. 2A, and Figs. 9B and 9C also correspond to Fig. 2B.

[0049] Fig. 9B is an enlarged view of EX7 in Fig. 9A. Fig. 9C is an enlarged view of EX7 in Fig. 9A, similar to Fig. 9B, but is a view for explaining an offensive at a position shifted from that in Fig. 9B.

[0050] As an example, the fastening stator conductors 10E are arranged at the positions of the holes on the radially outer side of the stator core 2 and the holes provided in the stator short-circuit ring 10C.

[0051] 8B and 6B, Fig. 8B of this embodiment shows that the fastening stator conductor 10D is not in close contact with the housing 13, but is provided at a position with the stator core 2 interposed between it and the housing 13. In this sense, the fastening stator conductor is denoted as 10E in Fig. 8A.

[0052] In this way, even when the fastened stator conductor 10D is not in close contact with the housing 13, the present invention is still within the scope of its disclosure.

[0053] The fastened stator conductor 10D may be formed over a wide area, for example, as shown in FIG. 9B. It may also be formed discontinuously, as shown in FIGS. 9B and 9C. For example, when the fastened stator conductor 10D is formed discontinuously, it is desirable to use a member that provides a fixing function after being driven, such as a rivet or a caulking plate. This makes it possible to fasten the electromagnetic steel sheets with the fastened stator conductor 10D, achieving a structure that is integrated with the fastening portion. Brass, which has excellent strength, may also be used as an example of the material used.

[0054] In this embodiment, the same effects as those of the fourth embodiment can be achieved in the area where the fastened stator conductor 10D is present.

[0055] Throughout the present specification, the stator conductors do not necessarily need to be in contact with the fastening portion, and may be provided independently at a distance from the fastening member when viewed in the radial direction of the stator.

[0056] Furthermore, throughout the present specification, it is sufficient to have at least one low resistance fastening member, and the spacing is not limited to equal spacing, but also includes unequal spacing.

[0057] The above examples illustrate the ideas and concepts of the present invention. Of course, the scope of the present invention also includes examples that are realized by combining the examples. Furthermore, as long as the disclosed ideas and concepts are used, any modifications or similar examples are also included within the scope of the present invention.

[0058] Furthermore, one example of the present invention described using the above embodiments can also be expressed as follows.

[0059] <No. 1> A rotating electric machine including a stator and a rotor provided inside the stator, wherein the stator has a stator core, stator slots arranged circumferentially around the stator core, and stator windings arranged in the stator slots, and the rotor has a central shaft, rotor slots, and rotor conductors, wherein the stator has low-resistance fastening members on the outer periphery of the stator core, and the low-resistance fastening members have fastening portions arranged on the outside of the stator and stator conductors arranged inside the fastening portions, and the electrical resistance of the stator conductors is lower than the electrical resistance of the fastening portions. <No. 2> The rotating electric machine according to <No. 1>, in which the strength of the fastening portions is higher than the strength of the stator conductors. <No. 3> The rotating electric machine according to <No. 1> or <No. 2>, which has stator short-circuit rings in the radial direction of the rotating electric machine that short-circuit the low-resistance fastening members. <No. 4> The rotating electric machine according to <No. 3>, in which the electrical resistance of the stator short-circuit rings is lower than the electrical resistance of the fastening portions. <No. 5> The rotating electric machine according to <No. 4>, wherein the stator short-circuit rings are provided on both sides or both ends in the axial direction by the low-resistance fastening members. <No. 6> The rotating electric machine according to <No. 1> or <No. 2>, which has a housing provided outside the stator, and at least one of the housing and the fastening parts is a magnetic material. <No. 7> The rotating electric machine according to <No. 3>, which has a housing provided outside the stator, and at least one of the housing and the fastening parts is a magnetic material. <No. 8> A rotating electric machine having a stator and a rotor provided inside the stator, wherein the stator has a stator core, stator slots arranged circumferentially of the stator core, and stator windings arranged in the stator slots, and the rotor has a central shaft, rotor slots, and rotor conductors, wherein the stator has fastening stator conductors on the outer periphery of the stator core, and also has a housing provided outside the stator, and at least one of the housing and the fastening stator conductors is a magnetic material. <No. 9> The rotating electric machine according to <No. 8>, wherein the fastening stator conductors have a lower resistance than the housing.<No. 10> The rotating electric machine according to either <No. 8> or <No. 9>, wherein the fastened stator conductor faces the housing via the stator core. <No. 11> The rotating electric machine according to <No. 10>, wherein the fastened stator conductor has a formed portion and a non-formed portion. <No. 12> The rotating electric machine according to <No. 11>, wherein the formed portion is formed by a rivet or a caulking plate. <No. 13> The rotating electric machine according to <No. 8>, wherein the housing is a magnetic body and the fastened stator conductor is brass.

Claims

1. A rotating electric machine having a stator and a rotor arranged inside the stator, wherein the stator has a stator core, stator slots arranged circumferentially around the stator core, and stator windings arranged in the stator slots, and the rotor has a central shaft, rotor slots, and rotor conductors, wherein the stator has low-resistance fastening members on the outer periphery of the stator core, and the low-resistance fastening members have fastening portions arranged on the outside of the stator and stator conductors arranged inside the fastening portions, and the electrical resistance of the stator conductors is lower than the electrical resistance of the fastening portions.

2. A rotating electric machine according to claim 1, wherein the strength of said fastening portion is greater than the strength of said stator conductors.

3. A rotating electric machine according to claim 1 or 2, further comprising a stator short-circuit ring for short-circuiting between the low resistance fastening members in the radial direction of the rotating electric machine.

4. A rotating electric machine according to claim 3, wherein the electrical resistance of said stator short-circuit ring is lower than the electrical resistance of said fastening portion.

5. A rotating electric machine according to claim 4, wherein the stator short-circuit rings are provided on both sides or both ends in the axial direction by the low resistance fastening members.

6. A rotating electric machine according to claim 1 or 2, further comprising a housing provided on the outside of said stator, and at least one of said housing and said fastening portion being made of a magnetic material.

7. A rotating electric machine according to claim 3, further comprising a housing provided outside said stator, said housing and / or said fastening portion being made of a magnetic material.

8. A rotating electric machine having a stator and a rotor provided inside the stator, wherein the stator has a stator core, stator slots arranged circumferentially around the stator core, and stator windings arranged in the stator slots, and the rotor has a central shaft, rotor slots, and rotor conductors, wherein the stator has fastening stator conductors on the outer periphery of the stator core, and also has a housing provided outside the stator, and at least one of the housing and the fastening stator conductors is a magnetic material.

9. A rotating electric machine according to claim 8, wherein said fastened stator conductors have a lower resistance than said housing.

10. A rotating electric machine according to claim 8 or claim 9, wherein the fastening stator conductor faces the housing via the stator core.

11. A rotating electric machine according to claim 10, wherein said fastened stator conductors have formed portions and non-formed portions.

12. A rotating electric machine according to claim 11, wherein the forming portion is formed by a rivet or a caulking plate.

13. A rotating electric machine according to claim 8, wherein said housing is made of a magnetic material and said fastening stator conductors are made of brass.

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