Rotary electric machine

Abstract

To suppress the generation of eddy current and improve the output of a rotary electric machine by suppressing the axial magnetic flux of a stator core and increasing the magnetic flux at the end of the stator core.SOLUTION: A rotating electrical machine includes a rotor (1) having a rotor coil (3) that generates a magnetic field, and a stator (5) having a stator coil (6) provided on an outer diameter side of the rotor, a stator core (7) that supports the stator coil, and a magnetic shield (8) provided on an outer diameter side of the stator core.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a rotating electric machine equipped with a magnetic shield. [Background technology]

[0002] As renewable energy becomes more widespread and power generation systems are being built, and electrification is becoming more prevalent in various industrial fields, the application of strong magnetic field rotating electric machines (motors, generators, etc.) as rotating electric machines is being considered.

[0003] In this type of rotating electric machine, the strong magnetic field has a magnetic flux density in a range above the magnetic saturation of magnetic materials such as iron, so the iron core is made of a non-magnetic material to reduce weight, and a structure such as a frame installed on the outer periphery to support and fix the rotating electric machine, or a magnetic shield or magnetic core to prevent leakage of the magnetic field outside the machine, is often installed on the outer periphery of the rotating electric machine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-118485 Summary of the Invention [Problem to be solved by the invention]

[0005] In rotating electrical machines with strong magnetic fields, the stator core (iron core) is made of a non-magnetic material such as resin, reinforced plastic, or ceramic, but may also be made of a lightweight metal from the standpoint of strength.

[0006] If the stator core is made of metal, the magnetic flux from the magnetic field of the rotor coil generates eddy currents, resulting in losses, so it is sometimes made into an axially laminated structure. However, with a laminated structure, magnetic flux generated at the rotor coil end and magnetic flux flowing to the magnetic shield depending on the shape of the magnetic shield flow in the axial direction in a stator core made of non-magnetic material, and this can make it difficult to reduce eddy currents.

[0007] The present invention has been made to solve the above-mentioned problems, and aims to provide a rotating electric machine that can improve the output of the rotating electric machine by suppressing the axial magnetic flux of the stator core, thereby suppressing the generation of eddy currents and increasing the magnetic flux linking at the ends of the stator coil. [Means for solving the problem]

[0008] In order to solve the above problems, the rotating electric machine according to this embodiment is a rotating electric machine including a rotor having a rotor coil that generates a magnetic field, a stator coil provided on the outer diameter side of the rotor, a stator core that supports the stator coil, and a stator having a magnetic shield provided on the outer diameter side of the stator core, wherein when the axial length of the magnetic shield is Lms and the axial length of the straight part of the rotor coil is Lrc, Lms > Lrc. [Effects of the Invention]

[0009] According to this embodiment, it is possible to suppress the axial magnetic flux of the stator core and increase the magnetic flux at the ends of the stator core, thereby suppressing the generation of eddy currents and improving the output of the rotating electric machine. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a radial cross-sectional view of a main part of a rotating electric machine according to an embodiment of the present invention; [Figure 2] 1 is an axial cross-sectional view of a main part of a rotating electric machine according to an embodiment of the present invention; [Figure 3] FIG. 4 is a diagram showing dimensional information of main parts of the rotating electric machine according to the embodiment. [Figure 4] FIG. 2 is a plan view of a rotor coil of the rotating electric machine according to the embodiment. [Figure 5] 3 is a schematic diagram of magnetic flux generated by the rotating electric machine according to the embodiment; [Figure 6] FIG. 5 is a schematic diagram of magnetic flux generated in a rotating electric machine according to a comparative example. [Figure 7] Magnetic flux observation line used in effectiveness verification tests. [Figure 8] Axial magnetic flux density curve at observation line A. [Figure 9] Radial magnetic flux density curve at observation line B. [Figure 10] 3 is an output curve of the rotating electric machine according to the present embodiment. [Figure 11] FIG. 10 is a diagram showing a modified example of the rotating electric machine according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a rotating electrical machine according to the present invention will be described with reference to the drawings.

[0012] (Overall composition) FIG. 1 is a diagram showing an example of the cross-sectional shape (shape of a cross section parallel to the rotation axis) of the main part of the rotating electric machine according to this embodiment, and FIG. 2 is a diagram showing an example of the shape of the main part of the rotating electric machine when viewed in the axial direction.

[0013] In order to avoid complicating the illustration, only the upper half of the rotating electric machine is shown, and the lower half is omitted in Fig. 1. In Fig. 1, CL1 indicated by a dashed line represents the axial center line of the rotating shaft 2 of the rotating electric machine, and CL2 indicated by a dashed line represents the axial center (plane) of the rotating electric machine.

[0014] The rotating electric machine shown in Figures 1 and 2 is, for example, a strong magnetic field rotating electric machine, and includes a rotor 1 consisting of a rotating shaft 2, rotor coils 3 (3a, 3b) and a rotor coil support member 4, and a stator 5 arranged at a distance on the outer diameter side of the rotor 1 and consisting of a stator coil 6, a stator core 7, a magnetic shield 8 and a frame 9.

[0015] Although the stator 5 may be provided on the inner diameter side of the rotor 1, an example in which the stator 5 is provided on the outer diameter side of the rotor 1 is shown here.

[0016] (Rotor configuration) As shown in FIGS. 1 and 2, the rotor 1 includes a rotating shaft 2, a rotor coil (field portion) 3, and a rotor coil support member 4.

[0017] In this embodiment, the rotor coil 3 is used as the field means (field magnet portion) on the rotor side, but a permanent magnet can also be used instead of the rotor coil 3. In the rotor 1, the rotating shaft 2 is the central axis of the rotor 1 that rotates.

[0018] The annular rotor coil 3 is supported by a rotor coil support member 4 so that it can rotate together with the rotating shaft 2. As shown in Figures 1 and 4, the rotor coil 3 is made up of rotor coil straight portions 3a (axial length Lrc) that are parallel to the axial direction and rotor coil end portions 3b (axial length Lrce) that connect the rotor coil straight portions 3a, and is arranged so as to cover the periphery of the rotor coil support member 4, and functions as a field portion that generates a magnetic field.

[0019] Furthermore, 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 magnetic pole. The rotor coil support member 4 may constitute a part of the iron core, but may also be made of a non-magnetic material (non-magnetic material). In this case, the rotor coil 3 functions as an air-core coil.

[0020] FIG. 2 illustrates an example in which four rotor coils 3 and four rotor coil support members 4 are configured to form four magnetic poles (two north poles and two south poles).

[0021] However, the present invention is not limited to this example, and the number of rotor coils 3 and rotor coil support members 4 may be an even number other than four (the number of magnetic poles may be a number other than four).

[0022] (Stator configuration) As illustrated in FIGS. 1 and 2, the stator 5 includes a stator coil 6, a stator core (iron core) 7, a magnetic shield 8, and a frame 9.

[0023] In the stator 5, the stator coil 6 is supported by the stator core 7 and generates a magnetic field that interacts with the magnetic field generated by the rotor coil (field portion) 3.

[0024] Furthermore, if the magnetic field generated by the rotor coil (field magnet portion) 3 is strong, the stator core 7 is made of a non-magnetic material (non-magnetic body). Non-magnetic materials include resin, reinforced plastic, ceramic, and lightweight metal. If the non-magnetic material is metal, it may be laminated in the axial direction to reduce loss due to the magnetic field. Furthermore, depending on the strength of the magnetic field of the rotor coil (field magnet portion) 3, the stator core 7 may be made of a magnetic body.

[0025] 1 and 2, the magnetic shield 8 is provided so as to cover the stator core 7. In the example of FIGS. 1 and 2, the magnetic shield 8 is provided on the outer diameter side of the stator core 7, but if the stator 5 is disposed on an inner diameter side than the rotor 1, the magnetic shield 8 is provided on the inner diameter side of the stator core 7. In order to suppress loss due to the magnetic field of the rotor coil (field portion) 3, the magnetic shield 8 may be configured by stacking thin plates, such as electromagnetic steel plates, in the axial direction.

[0026] Furthermore, the frame 9 is made of a metal material and is disposed so as to surround the rotor 1 and the stator 5 .

[0027] (Dimensional information for each part) FIG. 3 shows dimensional information of each part of the rotating electric machine according to this embodiment, and FIG. 4 shows the shape and dimensional information of the rotor coil 3 as viewed from the arrow X in FIGS. The dimension information includes Lms, Lrc, Lrce, D1, D2, and D3 as described below.

[0028] However, in Figures 3 and 4, to make the configuration easier to understand, some of the dimensions of the parts shown in the figures are made larger or smaller than their actual sizes. Therefore, the size relationships between the dimensions of the parts shown in the figures may differ from the actual sizes. Also, although the rotor coil end portion 3b in Figure 4 is shown as an arc, it may be, for example, rectangular, and is not limited to the shape shown in the figures.

[0029] Lms: Axial length of magnetic shield 8 Lrc: Axial length of the rotor coil straight section 3a Lrce: Axial length of rotor coil end portion 3b D1: Length from the axial center CL2 to the end of the magnetic shield 8 D2: Length from the axial center CL2 to the end of the rotor coil straight section 3a (= 1 / 2 Lrc) D3: Length from the end of the rotor coil straight portion 3a to the end of the rotor coil end portion 3b (=Lrce)

[0030] (action) In the rotor 1 and stator 5 configured as described above, when the rotating electric machine operates as a generator, the magnetic field generated by the rotor coil 3 arranged around the rotating shaft 2 generates electric power through electromagnetic induction in the stator coil 6 of the stator 5. On the other hand, when the rotating electric machine operates as a motor, torque is generated by interaction with the magnetic field created by the current flowing through the stator coil 6 of the stator 5, causing the rotor 1 to rotate.

[0031] In this embodiment, as illustrated in Figure 3, the length Lms of the magnetic shield 8 is configured to be approximately the same as or longer than the length to the center of the coil end of the rotor coil 3 (Lrc + 1 / 2Lrce + 1 / 2Lrce = Lrc + Lrce) relative to the length of the rotor coil 3 (Lrc + 2Lrce).

[0032] That is, expressed as an inequality, Lms≧Lrc+Lrce(Lrc+½Lrce+½Lrce).

[0033] This configuration makes it possible to suppress the magnetic flux flowing in the axial direction in the stator core 7. Furthermore, in this embodiment, the magnetic flux linking the stator coil 6 can be increased, thereby increasing the output.

[0034] (Schematic diagram of magnetic flux) FIG. 5 is a schematic diagram showing the relationship between the magnetic shield 8 of this embodiment and magnetic flux, in which the magnetic flux is depicted in FIG.

[0035] FIG. 5 schematically shows magnetic flux H1 (broken line) due to rotor coil straight portion 3a and magnetic flux H2 (broken line) due to rotor coil end portion 3b.

[0036] The magnetic shield 8 of this embodiment guides the magnetic flux H1 in the radial direction relative to the stator core 7, and if the stator core 7 is made of a metal with a laminated structure, eddy currents are reduced.

[0037] Furthermore, since the magnetic flux H2 is also induced in the radial direction, the magnetic flux interlinking with the stator coil increases, and the voltage generated in the coil increases, resulting in an increase in output.

[0038] FIG. 6 is a schematic diagram showing, as a comparative example, the relationship with the magnetic flux when the length Lms of the magnetic shield 8 is less than Lrc+Lrce.

[0039] 6, similarly to FIG. 5, magnetic flux H1 (broken line) due to rotor coil straight portion 3a and magnetic flux H2 (broken line) due to rotor coil end portion 3b are schematically shown.

[0040] In the magnetic shield 8 of Fig. 6, the magnetic flux H1 near the rotor axial center CL2 is induced radially in the stator core 7, but the magnetic flux induced axially in the stator core 7 increases as it approaches the axial end. This means that even if the stator core 7 is made of metal with a laminated structure, eddy currents may be generated by the axial magnetic flux.

[0041] Also, some of the magnetic flux H2 does not interlink with the stator coil, and the voltage generated in the coil decreases, resulting in a decrease in output.

[0042] In this way, the present embodiment shown in FIG. 5 can suppress the magnetic flux flowing in the axial direction more than the comparative example shown in FIG. 6 and can increase the magnetic flux linking the stator coil 6, thereby suppressing the generation of eddy currents and increasing output.

[0043] (effect) The results of verifying the effect of the magnetic shield 8 of this embodiment will be explained with reference to FIGS. 7 to 10 using two graph examples.

[0044] Here, as magnetic flux observation lines, observation line A and observation line B were set on the stator core 7 as shown in Fig. 7. Observation line A is set on the stator core 7 close to the magnetic shield 8, and observation line B is set on the radial outside of the stator core 7.

[0045] Figure 8 is a graph showing the axial magnetic flux density distribution on observation line A, which shows the axial magnetic flux density as a function of distance from the axial center plane for cases without a magnetic shield and with magnetic shield lengths of 1 / 3Lrc, 2 / 3Lrc, Lrc, Lrc+Lrce, and Lrc+2Lrce.

[0046] From FIG. 8, it can be seen that the magnetic flux density at the end of the magnetic shield 8 is high because the magnetic flux is induced into the magnetic shield 8, but becomes relatively small once the magnetic shield length Lms is equal to or greater than Lcr+Lcre.

[0047] FIG. 9 is a graph showing the radial magnetic flux density distribution on observation line B, and the radial magnetic flux density was measured in the same manner as in FIG.

[0048] From Figure 9, it can be seen that when the magnetic shield length Lms is less than the length Lcr of the rotor coil end portion 3b, the magnetic flux density drops sharply from above the magnetic shield 8 in the axial direction, and the radial magnetic flux created by the rotor coil straight portion 3a cannot be used effectively.

[0049] On the other hand, when the magnetic shield length Lms is equal to or greater than Lcr, the magnetic flux density is relatively high even axially above the length Lcr of the rotor coil straight portion 3a, which means that the magnetic flux generated by the rotor coil end portion 3b can also be guided into radial magnetic flux.

[0050] Fig. 10 is a graph showing a comparison of output versus the length of the magnetic shield 8. The output is expressed as a pu value, where 1 is the value when the magnetic shield length Lms is the same as the length Lrc of the straight portion 3a of the rotor coil.

[0051] From FIG. 10, it can be seen that when the magnetic shield length Lms is equal to or greater than the length Lrc of the rotor coil straight portion 3a, the radial magnetic flux density increases (see FIG. 9), resulting in improved output.

[0052] Conversely, when the magnetic shield length Lms is less than the length Lrc of the rotor coil straight portion 3a, the magnetic flux generated by the rotor coil straight portion 3a cannot be used effectively, resulting in a decrease in output.

[0053] As described above, in the rotating electric machine according to this embodiment, by setting the magnetic shield length Lms to be equal to or greater than the length Lrc of the rotor coil straight portion 3a, and more preferably equal to or greater than the length Lrc of the rotor coil straight portion 3a plus the length Lrce of the rotor coil end portion 3b, it is possible to suppress the axial magnetic flux in the stator core portion and to significantly improve output by increasing the radial magnetic flux.

[0054] (Variation) FIG. 11 is a diagram showing an example of a cross-sectional shape (shape of a cross section perpendicular to the rotation axis) of a part of a rotating electric machine showing a modified example of the magnetic shield of this embodiment.

[0055] In the above-described FIG. 1, an example where the magnetic shield length Lms is greater than or equal to the length Lrc of the straight portion 3a of the rotor coil + the length Lrce of the end portion 3b of the rotor coil was shown. However, for the magnetic shield 8 shown in FIG. 10, Lms < Lrc + Lrce, but magnetic pressing plates 10 with an axial length of Lmp press the magnetic shield 8 and / or the stator core 7 from both axial ends, and the combined length of the magnetic shield 8 and the pressing plates 10 is Lrc + Lrce or more (Lms + 2Lmp ≧ Lrc + Lrce), whereby the same effect can be obtained.

[0056] Particularly when the stator core 7 has a laminated structure or the magnetic shield 8 has a laminated structure, by tightening from both ends with the pressing plates 10, while fixing the stator core 7 and the magnetic shield 8, it is possible to obtain the effects of suppressing the axial magnetic flux of the stator core portion and improving the output.

[0057] As described above, the embodiments of the present invention have been explained. However, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations 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 also included in the invention described in the claims and its equivalent scope.

Description of Reference Numerals

[0058] 1...rotor, 2...rotating shaft, 3...rotor coil (field section), 3a...straight section of rotor coil, 3b...rotor coil end section, 4...rotor coil support member, 5...stator, 6...stator coil, 7...stator core (iron core), 8...magnetic shield, 9...frame, 10...pressure plate, A, B...observation line, CL1...rotating shaft center line, CL2...axial center (surface), Lms...axial length of magnetic shield, Lrc...axial length of straight section of rotor coil..., Lrce...axial length of rotor coil end section, D1...length from axial center CL2 to end of magnetic shield, D2...length from axial center CL2 to end of straight section of rotor coil, D3...length from end of straight section of rotor coil to end of rotor coil end section, H1...magnetic flux lines of straight section of rotor coil, H2...magnetic flux lines of rotor coil end section

Claims

1. a rotor having a rotor coil that generates a magnetic field; a stator having a stator coil provided on the outer diameter side of the rotor, a stator core supporting the stator coil, and a magnetic shield provided on the outer diameter side of the stator core, A rotating electric machine characterized in that, when the axial length of the magnetic shield is Lms and the axial length of the straight portion of the rotor coil is Lrc, Lms>Lrc.

2. 2. The rotating electric machine according to claim 1, wherein Lms≧Lrc+Lrce is satisfied, where Lrce is the axial length of the end portion of the rotor coil.

3. a presser plate for pressing the magnetic shield and / or the stator core on both axial ends of the magnetic shield; 2. The rotating electric machine according to claim 1, wherein, when the axial length of the magnetic shield is Lms, the axial length of the pressure plate is Lmp, the axial length of the straight portion of the rotor coil is Lrc, and the axial length of the end portion of the rotor coil is Lrce, Lms + 2Lmp ≧ Lrc + Lrce.

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