Rotary electric machine

Abstract

A rotary electric machine 100 comprises: a stator 1 that has a slot 9 and a winding 10; and a rotor 2 that has permanent magnets 3 and a rotor core 12 and is arranged relative to the stator 1 with an air gap 13 therebetween. The permanent magnets 3 comprise: main magnets 31 that each have magnetic poles oriented in the radial direction of the rotor 2; and auxiliary magnets 32 that are adjacent to the main magnets 31 and that each have magnetic poles oriented in the circumferential direction of the rotor 2. The main magnets 31 and the auxiliary magnets 32 are alternately arranged according to the Halbach array on the surface of the rotor core 12. The spacing between the auxiliary magnets 32 and the stator 1 is configured to be larger than the spacing between the main magnets 31 and the stator 1.

Description

Rotating electric machines

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

[0002] JP2022-161445A discloses a rotating electric machine having an outer rotor in which main magnets and auxiliary magnets are arranged according to a Halbach array.

[0003] The rotating electric machine described in the above document is configured to increase the magnetic flux density of the magnetic poles by arranging the main magnets and auxiliary magnets in a Halbach array, and the main magnets and auxiliary magnets of the rotor are arranged so as to have the same air gap with the stator. In such a configuration, the magnetic flux of the auxiliary magnets, which is used to change the magnetic flux density of the main magnets, interlinks with the stator, generating iron loss, which causes a corresponding decrease in the efficiency of the rotating electric machine.

[0004] The present invention has been made in view of the above problems, and has an object to provide a rotating electric machine capable of suppressing a decrease in efficiency.

[0005] According to one aspect of the present invention, a rotating electric machine includes a stator having slots and windings, and a rotor having permanent magnets and a rotor core, with an air gap between the stator and the rotor. The permanent magnets include main magnets whose magnetic poles are oriented in the radial direction of the rotor, and auxiliary magnets adjacent to the main magnets whose magnetic poles are oriented in the circumferential direction. These main magnets and auxiliary magnets are alternately arranged on the surface of the rotor core in a Halbach array. The distance between the auxiliary magnets and the stator is configured to be larger than the distance between the main magnets and the stator.

[0006] Fig. 1 is a cross-sectional view of a rotating electric machine according to an embodiment of the present invention. Fig. 2 is an enlarged view of a main portion of the rotating electric machine according to the present invention. Fig. 3 is a cross-sectional view of a rotating electric machine according to a modified example of the present invention. Fig. 4 is a cross-sectional view of a rotating electric machine according to another modified example of the present invention. Fig. 5 is a cross-sectional view of a rotating electric machine according to yet another modified example of the present invention. Fig. 6 is a cross-sectional view of a rotating electric machine according to yet another modified example of the present invention. Fig. 7 is a cross-sectional view of a rotating electric machine according to yet another modified example of the present invention. Fig. 8 is an enlarged view of a main portion of a rotating electric machine according to a modified example of the present invention.

[0007] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0008] 1 is a cross-sectional view perpendicular to the axial direction of a rotating electrical machine 100 according to a first embodiment of the present invention, showing a part of the overall configuration. The remaining parts of the overall configuration are successive repetitions of the partial configuration shown in FIG.

[0009] The rotating electric machine 100 of this embodiment includes a ring-shaped stator 1, a rotor 2 that is concentric with the stator 1 and is arranged on the inner periphery of the stator 1 with an air gap 13 between it and the rotor 2, and permanent magnets 3 that are arranged on the inner periphery of the rotor 2 and face the air gap 13. The permanent magnets 3 are made up of main magnets 31 and auxiliary magnets 32. The main magnets 31 and auxiliary magnets 32 are arranged alternately in the circumferential direction in a Halbach array.

[0010] The rotating electric machine 100 of this embodiment is mounted on an electric vehicle and functions as an electric motor that drives the wheels. It also functions as a generator that generates electricity (regenerative) by receiving rotation of the wheels. Note that the rotating electric machine 100 may also be used as a drive device for devices other than automobiles, such as various electrical appliances or industrial machines.

[0011] The stator 1 is composed of a ring-shaped stator core 11 and stator windings 10 wound in slots 9 formed in the stator core 11. The stator core 11 is formed with a plurality of teeth 8 protruding toward the inner periphery (toward the rotor 2) and slots 9 which are spaces between adjacent teeth 8. The stator core 11 is composed of laminated electromagnetic steel sheets.

[0012] The rotor 2 has a rotor core 12. The rotor core 12 is formed by laminating electromagnetic steel sheets. A groove structure 30 for fixing the permanent magnets 3 is formed on the outer peripheral surface (surface) of the rotor core 12. The main magnets 31 and auxiliary magnets 32 abut against the outer peripheral side of this groove structure 30 and are fixed thereto with an adhesive. The inner peripheral side of the rotor 2 is provided with a shaft hole 14 to which the rotor shaft 15 is fixed.

[0013] In the rotor 2 of this embodiment, the main magnets 31 and the auxiliary magnets 32 are arranged alternately in the circumferential direction along the outer periphery of the rotor core 12 in a Halbach array. The cross-sectional shape of the main magnets 31 taken along the radial direction is a rectangle with a long side in the circumferential direction. The auxiliary magnets 32 are arranged between the main magnets 31. The cross-sectional shape of the auxiliary magnets 32 taken along the radial direction is a rectangle with a long side shorter than that of the main magnets 31. The main magnets 31 and auxiliary magnets 32 are fixed to the outer circumferential surface of the rotor core 12 using an adhesive.

[0014] The main magnets 31 are arranged so that their magnetic poles are in the radial direction of the rotor 2, and so that adjacent main magnets 31 have opposite magnetic poles. The auxiliary magnets 32 are arranged so that their magnetic poles are in the circumferential direction of the rotor 2, i.e., so that their magnetic poles are perpendicular to those of the main magnets 31. With this configuration, the magnetic flux of the main magnet 31, which is the magnetic pole center, is deflected by the auxiliary magnets 32 toward the stator 1, and the magnetic flux linking with the stator 1 can be increased, thereby improving the torque efficiency of the rotating electric machine 100.

[0015] The rotor 2 has magnetic poles formed by two circumferentially adjacent main magnets 31 and an auxiliary magnet 32 ​​between them, and in Fig. 1, four magnetic poles are formed by four main magnets 31. The opposing stator 1 has three teeth 8 and three slots 9 arranged thereon, with two magnetic poles facing each tooth 8.

[0016] In this way, the rotating electric machine 100 is configured so that two magnetic poles face each tooth 8. The relationship between these satisfies S = R ± P, where S is the number of slots, R is the number of pole pairs of the permanent magnet 3, and P is the number of pole pairs of the stator winding 10 of the stator 1. In this embodiment, by configuring the rotating electric machine 100 in this way, modulated flux linkage is generated in the stator 1 when the rotor 2 rotates, and a magnetic field is generated in the stator 1 in synchronization with the modulated flux linkage. As a result, an advance in the electrical angle is generated by the magnetic field of the stator 1, and this effect is applied to the magnetic flux of the rotor 2, thereby increasing the torque of the rotating electric machine 100.

[0017] Next, the relationship between the permanent magnet 3 and the air gap 13 will be described.

[0018] The rotating electric machine 100 of this embodiment is configured to increase the magnetic flux density of the magnetic poles of the rotor 2 by arranging the main magnets 31 and the auxiliary magnets 32 in a Halbach array, and further increase torque by providing three slots 9 and four magnetic poles as described above. Generally, in order to allow the magnetic flux of the rotor 2 to act on the stator 1, it is desirable to have a small distance between the permanent magnets 3 and the stator 1, i.e., a small air gap 13. On the other hand, if the auxiliary magnets 32 for changing the magnetic flux density of the main magnets 31 are arranged close to the stator 1, the magnetic flux of the auxiliary magnets 32 may interlink with the stator 1, causing iron loss in the stator 1. In this case, there is a problem in that the torque efficiency of the rotating electric machine 100 decreases accordingly.

[0019] Therefore, in this embodiment, the influence of iron loss caused by the auxiliary magnet 32 ​​is minimized and torque efficiency is improved by the following configuration.

[0020] 1 , the rotor 2 is configured so that the distance between the auxiliary magnet 32 ​​and the inner peripheral surface of the stator 1 (i.e., the inner peripheral surface of the teeth 8) is larger than the distance (air gap 13) between the main magnet 31 and the inner peripheral surface of the stator 1 (i.e., the tip surfaces of the teeth 8). In other words, the auxiliary magnet 32 ​​is disposed so that the outer surface of the auxiliary magnet 32 ​​is recessed from the air gap 13.

[0021] Fig. 2 is an enlarged view of part A in Fig. 1. As shown in Fig. 2, auxiliary magnet 32 ​​is arranged so that its outer surface, i.e., side 32a of auxiliary magnet 32 ​​facing stator 1, is located between center line CL in the radial direction of main magnet 31 and side 31d of main magnet 31 on the side opposite to stator 1.

[0022] By arranging the auxiliary magnets 32 at a distance from the stator 1 in this way, the magnetic flux linking from the auxiliary magnets 32 to the stator 1 side is reduced, thereby reducing iron loss generated in the stator 1. Note that even with this configuration, there is almost no effect on the effect of the auxiliary magnets 32 deflecting the magnetic flux of the main magnets 31 toward the stator 1 side.

[0023] Furthermore, in the rotor 2, a space is defined by adjacent main magnets 31 and the auxiliary magnets 32 located between these main magnets 31. As shown in Fig. 2, this space exposes, to the air gap 13, a first side 31a facing the stator 1, and second and third sides 31b and 31c adjacent to both ends of the first side 31a, out of the four sides surrounding the outer periphery of the rectangular main magnet 31.

[0024] With this configuration, the surface area of ​​the main magnet 31 exposed to the air gap 13 is increased, and the main magnet 31 can be cooled by the air circulating through the air gap 13 as the rotor 2 rotates.

[0025] As described above, the rotating electric machine 100 of this embodiment includes a stator 1 having slots 9 and stator windings 10, and a rotor 2 having permanent magnets 3 and a rotor core 12 and arranged with an air gap 13 between it and the stator 1. The permanent magnets 3 are configured such that main magnets 31, whose magnetic poles are oriented in the radial direction of the rotor 2, and auxiliary magnets 32, adjacent to the main magnets 31 and whose magnetic poles are oriented in the circumferential direction of the rotor 2, are alternately arranged on the surface of the rotor core in a Halbach array, and the distance between the auxiliary magnets 32 and the stator 1 is larger than the distance between the main magnets 31 and the stator 1.

[0026] In this configuration, by arranging the auxiliary magnets 32 at a distance from the stator 1, the magnetic flux linking from the auxiliary magnets 32 to the stator 1 side is reduced, thereby reducing iron loss generated in the stator 1. Even with this configuration, by arranging the auxiliary magnets 32 between adjacent main magnets 31, it is possible to prevent a decrease in the torque efficiency of the rotating electric machine 100 due to iron loss, without affecting the effect of deflecting the magnetic flux of the main magnets 31, which are the magnetic pole centers, toward the stator 1 side.

[0027] Furthermore, in this embodiment, the side of the auxiliary magnet 32 ​​that faces the stator 1 is exposed to the air gap 13, which suppresses iron loss caused by the magnetic flux of the auxiliary magnet 32 ​​in the rotor core 12. This makes it possible to further prevent a decrease in the torque efficiency of the rotating electric machine 100.

[0028] In addition, in this embodiment, the radial cross section of the rotor 2 of the main magnet 31 is rectangular, and of the four sides surrounding its outer periphery, the first side 31a facing the stator 1, and the second side 31b and third side 31c adjacent to both ends of the first side 31a are exposed to the air gap 13.

[0029] In this configuration, the surface area of ​​the main magnet 31 exposed to the air gap 13 is increased, allowing the main magnet 31 to be effectively cooled by the air circulating through the air gap 13 as the rotor 2 rotates.

[0030] In addition, in this embodiment, the auxiliary magnet 32 ​​is positioned so that the edge 32a facing the stator 1 is located between the radial center of the main magnet 31 and the edge 31d on the opposite side of the main magnet 31 facing the stator 1.

[0031] In this configuration, the auxiliary magnets 32 are reliably positioned between adjacent main magnets 31, so that the auxiliary magnets 32 can be positioned away from the stator 1 while maintaining the effect of deflecting the magnetic flux of the main magnet 31, which is the magnetic pole center, toward the stator 1. This reduces iron loss occurring in the stator 1, and makes it possible to prevent a decrease in the torque efficiency of the rotating electric machine 100 due to iron loss.

[0032] In this embodiment, when the number of slots in the stator 1 is S, the number of magnetic pole pairs in the rotor 2 is R, and the number of pole pairs in the stator 1 is P, S=P±R.

[0033] In this configuration, when the rotor 2 rotates, a modulated interlinkage magnetic flux is generated in the stator 1, and a magnetic field is generated in the stator 1 in synchronization with the modulated interlinkage magnetic flux, thereby causing the magnetic field of the stator 1 to advance the electrical angle, and this effect is applied to the magnetic flux of the rotor 2, thereby increasing the torque of the rotating electric machine 100.

[0034] Next, a modification of this embodiment will be described.

[0035] FIG. 3 is a cross-sectional view perpendicular to the axial direction of a rotating electrical machine 100 according to a modified example of this embodiment.

[0036] The rotating electric machine 100 of this modified example is configured as an outer rotor type motor in which the rotor 2 is disposed on the outer periphery of the stator 1 .

[0037] 3, the rotating electric machine 100 includes a ring-shaped stator 1, a rotor 2 that is concentric with the stator 1 and is arranged on the outer periphery of the stator 1 with an air gap 13 between them, and permanent magnets 3 that are arranged on the inner periphery of the rotor 2 on a surface that faces the stator 1 across the air gap 13. The permanent magnets 3 are made up of main magnets 31 and auxiliary magnets 32. The main magnets 31 and auxiliary magnets 32 are arranged alternately in the circumferential direction in a Halbach array.

[0038] 3, the rotor 2 is configured so that the distance between the auxiliary magnet 32 ​​and the inner peripheral surface of the stator 1 (tip surfaces of the teeth 8) is larger than the distance (air gap 13) between the main magnet 31 and the inner peripheral surface of the stator 1 (tip surfaces of the teeth 8). In other words, the inner surface of the auxiliary magnet 32 ​​is positioned at a position recessed from the air gap 13.

[0039] As described above, in this modification of the present embodiment, the rotor 2 is configured as an outer rotor that is disposed on the outer diameter side of the stator 1. Even when configured as an outer rotor type rotating electric machine 100, by disposing the auxiliary magnets 32 away from the stator 1, as described above, the magnetic flux linking from the auxiliary magnets 32 to the stator 1 side is reduced, thereby reducing iron loss generated in the stator 1. This makes it possible to prevent a decrease in the torque efficiency of the rotating electric machine 100.

[0040] FIG. 4 is a cross-sectional view perpendicular to the axial direction of a rotating electrical machine 100 according to another modified example of this embodiment.

[0041] The rotating electric machine 100 of the modified example shown in FIG. 4 is similar in configuration to that of FIG. 1, but differs in that a non-magnetic member 40 is provided on the outer periphery of the auxiliary magnet 32.

[0042] 4, a non-magnetic member 40 is filled into the space defined by adjacent main magnets 31 and the auxiliary magnets 32 located between these main magnets 31. The non-magnetic member 40 is made of a resin, for example, a thermoplastic adhesive.

[0043] In this manner, in this modified example, the non-magnetic member 40 is arranged in the space defined by adjacent main magnets 31 and the auxiliary magnets 32 located between these main magnets 31 .

[0044] This configuration increases the strength with which the main magnets 31 and auxiliary magnets 32 are fixed to the outer periphery of the rotor core 12. Furthermore, the surfaces of the main magnets 31 and the non-magnetic member 40 can be configured to be flush with each other, so the surfaces of the permanent magnets 3 on the outer periphery of the rotor 2 form a gentle circumferential surface, reducing the effect of air resistance when the rotor 2 rotates.

[0045] FIG. 5 is a cross-sectional view perpendicular to the axial direction of a rotating electrical machine 100 according to yet another modification of this embodiment.

[0046] The rotating electric machine 100 of the modified example shown in FIG. 5 is similar in configuration to that of FIG. 3, but differs in that it includes a non-magnetic member 40 on the outer periphery of the auxiliary magnet 32, similar to the modified example described in FIG. 4.

[0047] More specifically, as shown in FIG. 5, the space defined by adjacent main magnets 31 and the auxiliary magnets 32 located between these main magnets 31 was filled with the non-magnetic material 40 as described above.

[0048] 4, this configuration makes it possible to increase the strength with which the main magnets 31 and auxiliary magnets 32 are fixed to the outer periphery of the rotor core 12. Furthermore, because the surfaces of the permanent magnets 3 on the inner periphery of the rotor 2 are smooth, the influence of air resistance when the rotor 2 rotates is reduced.

[0049] FIG. 6 is a cross-sectional view perpendicular to the axial direction of a rotating electrical machine 100 according to yet another modification of this embodiment.

[0050] The rotating electric machine 100 of the modified example shown in FIG. 6 has a configuration similar to that of FIG. 4, but differs in the shape of the non-magnetic member 40 provided on the outer periphery of the auxiliary magnet 32.

[0051] More specifically, as shown in FIG. 4, a concave-convex fin structure 40a is formed on the side facing the air gap 13 of a non-magnetic member 40 filled in the space defined by adjacent main magnets 31 and auxiliary magnets 32 located between these main magnets 31.

[0052] In this modified example, the non-magnetic member 40 is configured to have an uneven fin structure 40a on the side facing the air gap 13, which increases the strength with which the main magnets 31 and auxiliary magnets 32 are fixed to the outer periphery of the rotor core 12, and by increasing the surface area of ​​the non-magnetic member 40, the main magnets 31 and auxiliary magnets 32 can be more effectively cooled by the air circulating through the air gap 13 as the rotor 2 rotates.

[0053] FIG. 7 is a cross-sectional view perpendicular to the axial direction of a rotating electrical machine 100 according to yet another modification of the present embodiment.

[0054] The modified rotating electric machine 100 shown in FIG. 7 is similar to the configuration shown in FIG. 5, but differs in that the shape of the non-magnetic member 40 that can be fitted around the outer periphery of the auxiliary magnet 32 ​​is the same as the configuration described in FIG. 6.

[0055] More specifically, as shown in Figure 7, a fin structure 40a with a concave-convex shape is formed on the side facing the air gap 13 of a non-magnetic member 40 that fills the space defined by adjacent main magnets 31 and the auxiliary magnets 32 located between these main magnets 31.

[0056] By configuring in this manner, as with the modified example described in Figure 6, the strength with which the main magnets 31 and auxiliary magnets 32 are fixed to the outer periphery of the rotor core 12 can be increased, and the surface area of ​​the non-magnetic material member 40 is increased, so that the main magnets 31 and auxiliary magnets 32 can be cooled by the air circulating through the air gap 13 as the rotor 2 rotates.

[0057] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0058] In this embodiment, the main magnets 31 and auxiliary magnets 32 are fixed to the outer periphery of the rotor core 12, but the rotor core 12 may also be provided with a structure (for example, a hook-shaped claw portion) for engaging the main magnets 31 and auxiliary magnets 32.

[0059] 8 , the rotor core 12 may be configured to include first claws 121 that lock both circumferential end portions of the main magnet 31 from the outer periphery, and second claws 122 that lock both circumferential end portions (or one end portion) of the auxiliary magnet 32 ​​from the outer periphery. With this configuration, the main magnet 31 and the auxiliary magnet 32 ​​can be fixed to the rotor core 12 more reliably.

[0060] Alternatively, magnet holes corresponding to the shapes of the main magnets 31 and auxiliary magnets 32 may be formed in the rotor core 12 in the direction of the rotation axis, and the main magnets 31 and auxiliary magnets 32 may be embedded in the magnet holes, respectively.

[0061] Furthermore, although the main magnet 31 in this embodiment is rectangular, the side facing the stator 1 may be formed in an arc shape so as to face the outer peripheral surface of the stator 1 (the tip surfaces of the teeth 8).

Claims

1. A rotating electric machine comprising a stator having slots and windings, and a rotor having permanent magnets and a rotor core and arranged with an air gap between it and the stator, wherein the permanent magnets comprise main magnets whose magnetic poles are oriented in the radial direction of the rotor, and auxiliary magnets adjacent to the main magnets whose magnetic poles are oriented in the circumferential direction of the rotor, the main magnets and the auxiliary magnets are alternately arranged on the surface of the rotor core in a Halbach array, and the distance between the auxiliary magnets and the stator is larger than the distance between the main magnets and the stator.

2. A rotating electric machine according to claim 1, wherein the side of the auxiliary magnet facing the stator is exposed to the air gap.

3. A rotating electric machine according to claim 1, wherein the radial cross section of the rotor of the main magnet is rectangular, and of the four sides surrounding the outer periphery, a first side facing the stator and second and third sides adjacent to both ends of the first side are exposed to the air gap.

4. A rotating electric machine according to claim 1, wherein the auxiliary magnet is arranged so that the side facing the stator is located between the radial center of the main magnet and the side of the main magnet opposite the side facing the stator.

5. A rotating electric machine according to claim 1, wherein a non-magnetic member is disposed in a space defined by adjacent main magnets and the auxiliary magnets located between the main magnets.

6. A rotating electric machine according to claim 5, wherein the non-magnetic member has a concave-convex fin structure on the side facing the air gap.

7. A rotating electric machine according to any one of claims 1 to 6, wherein the rotor is configured as an outer rotor disposed on the outer diameter side of the stator.

8. A rotating electric machine according to claim 1, wherein, when the number of slots in the stator is S, the number of magnet pole pairs in the rotor is R, and the number of pole pairs in the stator is P, S=P±R.

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