Rotor and rotating electric machine

Abstract

According to an embodiment, a rotor (100) comprises: a rotor shaft (110); a rotor core (120) having a plurality of flux barrier bands (120x, 120y) formed at intervals in the radial direction at respective magnetic poles (101) and in a substantially convex shape toward a rotational central axis; and, in each of the flux barrier bands, a plurality of permanent magnets 130 that include rare earth magnets not containing a heavy rare earth element and / or heavy rare earth magnets containing a heavy rare earth element and are arranged in line symmetry with respect to an M-axis. When viewed with regard to the flux barrier band (120y), in which both rare earth magnets and heavy rare earth magnets are stored, the rare earth magnets are thicker in a direction of magnetization than the thickness of the heavy rare earth magnets in the direction of magnetization, and are also disposed on the side close to the M-axis.

Description

Rotor and rotating electric machine

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

[0002] Synchronous machines that use permanent magnets in their rotors often use an interior permanent magnet (IPM) structure in which the permanent magnets are located inside the rotor core. Rare-earth magnets such as neodymium magnets are used as permanent magnets instead of ferrite magnets, thereby achieving smaller size, higher output, and higher efficiency. Furthermore, in harsh operating environments, such as high operating temperatures, heavy rare-earth magnets containing heavy rare-earth elements such as dysprosium (Dy) and terbium (Tb) are used to improve coercivity.

[0003] 9 is a partial cross-sectional view showing an example of the configuration of a conventional rotating electric machine, which shows an example of the configuration within one magnetic pole of the stator 10 and rotor 30.

[0004] The rotor core 33 of the rotor 30 has two outer storage holes 33a that form the outer flux barrier band, each of which houses an outer magnet 31, and two inner storage holes 33b that form the inner flux barrier band, each of which houses an inner magnet 32.

[0005] The two outer magnets 31 and the two inner magnets 32 are arranged symmetrically with respect to the center of the magnetic pole. Both the two outer magnets 31 and the two inner magnets 32 are heavy rare earth magnets.

[0006] JP 2008-130781 A International Publication No. 03 / 079516 Japanese Patent No. 5891089 A Japanese Patent Application Laid-Open No. 2012-29351 A

[0007] As mentioned above, heavy rare earth magnets have the advantage of suppressing the temperature degradation of coercivity and ensuring heat resistance. However, heavy rare earth elements have limited reserves in the earth's crust and are only produced in limited areas, which means that their prices and supply are unstable.

[0008] For this reason, it is desirable to achieve torque / output performance and demagnetization resistance equivalent to that of rotating electrical machines that include heavy rare earth magnets, using rare earth magnets that contain as few heavy rare earth elements as possible.

[0009] The problem to be solved by the present invention is to provide a rotor and a rotating electric machine that can reduce the amount of heavy rare earth elements used while maintaining performance.

[0010] In order to achieve the above-mentioned object, a rotor according to an embodiment of the present invention comprises: a rotor shaft extending in the direction of a central axis of rotation; a rotor core attached radially outward of the rotor shaft, and having a plurality of flux barrier bands formed on each magnetic pole at radially spaced intervals, the flux barrier bands including bridges and non-magnetic regions that are generally convex toward the central axis of rotation; and a plurality of permanent magnets that each include a rare earth magnet that does not contain a heavy rare earth element and a heavy rare earth magnet that contains a heavy rare earth element, and are arranged in line symmetry with respect to an M-axis extending from the central axis of rotation in a cross section perpendicular to the central axis of rotation, and when viewed from the flux barrier band containing both the rare earth magnets and the heavy rare earth magnets, the rare earth magnets have a greater thickness in the magnetization direction than the heavy rare earth magnets and are arranged closer to the M-axis.

[0011] FIG. 1 is a longitudinal sectional view showing the configuration of a rotating electric machine according to a first embodiment; FIG. 2 is a partial cross sectional view showing the configuration of a rotating electric machine according to the first embodiment; FIG. 3 is a partial cross sectional view showing the configuration of a rotating electric machine according to a first modified example of the first embodiment; FIG. 4 is a partial cross sectional view showing the configuration of a rotating electric machine according to a second modified example of the first embodiment; FIG. 5 is a partial cross sectional view showing the configuration of a rotating electric machine according to a second embodiment; FIG. 6 is a partial cross sectional view showing the configuration of a rotating electric machine according to a modified example of the second embodiment; FIG. 7 is a partial cross sectional view showing the configuration of a rotating electric machine according to a third embodiment; FIG. 8 is a partial cross sectional view showing the configuration of a rotating electric machine according to a modified example of the third embodiment; FIG. 9 is a partial cross sectional view showing an example of the configuration of a conventional rotating electric machine;

[0012] Hereinafter, a rotor and a rotating electric machine according to an embodiment of the present invention will be described with reference to the drawings. Here, the same or similar parts are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0013] First Embodiment FIG. 1 is a vertical cross-sectional view showing the configuration of a rotating electrical machine according to a first embodiment.

[0014] The rotating electric machine 1 includes a rotor 100 , a stator 10 , a bearing 21 , a bearing bracket 22 , and a frame 23 .

[0015] The rotor 100 has a rotor shaft 110 that extends in a direction parallel to the rotation center axis CL (axial direction) and rotates around the rotation center axis CL, a rotor core 120 that is attached radially outside the rotor shaft 110, and a plurality of permanent magnets 130 that are housed inside the rotor core 120 and extend parallel to the rotation center axis CL.

[0016] The stator 10 has a stator core 11 disposed radially outside the rotor core 120 so as to surround the rotor core 120 with a gap therebetween, and a stator winding 15 wound around the stator core 11 .

[0017] The bearings 21 are arranged on both outer sides of the rotor core 120 in the axial direction of the rotor shaft 110, and rotatably support the rotor shaft 110. The bearing brackets 22 stationarily support the respective bearings 21. The frame 23 is cylindrical, and both ends thereof are connected to the respective bearing brackets 22, and support the respective bearing brackets 22.

[0018] Fig. 2 is a partial cross-sectional view showing the configuration of a rotating electric machine according to the first embodiment. Fig. 2 is a partial cross-sectional view perpendicular to the rotation axis CL (Fig. 1) showing a portion of the stator 10 and rotor 100 in the range of the magnetic pole 101 sandwiched between two R axes. Note that the rotor shaft 110 (Fig. 1) is not shown.

[0019] The stator 10 has a stator core 11 and stator windings 15. Stator slots 13 are formed at intervals in the circumferential direction on the inner periphery of the stator core 11. Adjacent stator slots 13 form stator teeth 12. The stator windings 15 are wound around the stator teeth 12.

[0020] The rotor 100 has a plurality of permanent magnets 130 arranged symmetrically about the M axis at the center of the circumferential angle (center in the circumferential direction) sandwiched between the two R axes in the magnetic pole 101. In detail, the plurality of permanent magnets 130 comprises two first layer first magnets 131a arranged symmetrically with respect to each other about the M axis, a first layer central magnet 131b arranged on the M axis, two second layer outer magnets 132a arranged symmetrically with respect to each other about the M axis, and a second layer inner magnet 132b arranged symmetrically with respect to each other about the M axis.

[0021] As indicated by N and S on each of the permanent magnets 130 in Fig. 2, the surface on the radially outer side and closer to the M axis is magnetized in a direction such that the N pole and the opposite surface are magnetized in a direction such that the S pole. Although not shown, the magnetic poles 101 adjacent to both sides of the magnetic pole 101 shown in Fig. 2 in the circumferential direction have N and S orientations opposite to each other, and the magnetic poles 101 are arranged such that the magnetization direction is reversed alternately in the circumferential direction.

[0022] Of the permanent magnets 130, the shaded areas are heavy rare earth magnets, and the vertically shaded areas are rare earth magnets containing rare earth elements but not heavy rare earth elements (hereinafter referred to as "rare earth magnets"). That is, the two first layer magnets 131a and the two second layer outer magnets 132a are heavy rare earth magnets, and the first layer central magnet 131b and the two second layer inner magnets 132b are rare earth magnets.

[0023] As shown in Figure 2, the first layer central magnet 131b and the two second layer inner magnets 132b, which are rare earth magnets, are arranged relatively closer to the M axis in each flux barrier band, and the two first layer magnets 131a and the two second layer outer magnets 132a, which are heavy rare earth magnets, are arranged relatively closer to the R axis in each flux barrier band.

[0024] Here, examples of rare earth magnets that can be used include neodymium magnets containing neodymium (Nd), magnets containing samarium (Sm), etc. Examples of heavy rare earth magnets that can be used include magnets containing dysprosium (Dy), terbium (Tb), etc.

[0025] Comparing the magnetization curves (J-H curves) of rare earth magnets and heavy rare earth magnets, the remanence Jr is roughly the same, but the coercivity Hcj of the rare earth magnet is, for example, about half that of the heavy rare earth magnet. In this embodiment, a rare earth magnet is used whose coercivity Hcj at 150°C is less than two-thirds of the coercivity Hcj of the heavy rare earth magnet.

[0026] Here, the first layer first magnet 131a and the second layer outer magnet 132a, which are heavy rare earth magnets, have the same specifications, with the same material, cross-sectional shape, and dimensions. The same is true for the first layer central magnet 131b and the second layer inner magnet 132b, which are rare earth magnets. In this way, in terms of manufacturing costs, it is preferable to use magnets with the same specifications. However, if the benefits of not using the same specifications outweigh the benefits, magnets with different specifications may be used.

[0027] The thickness of the first layer central magnet 131b and the two second layer inner magnets 132b, which are rare earth magnets, in the direction of magnetization is greater than the thickness of the first layer magnet 131 and the two second layer outer magnets 132a in the direction of magnetization. Figure 2 shows a case where the thickness is, for example, about twice as large.

[0028] The rotor core 120 has a first flux barrier band 120x, which is a radially outer layer, and which is made up of multiple elements that each penetrate the rotor core 120 in the axial direction, and a second flux barrier band 120y, which is a radially inner layer, and which is made up of multiple elements that each penetrate the rotor core 120 in the axial direction.

[0029] The first flux barrier band 120x has two first-layer magnet storage holes 121, each housing two first-layer magnets 131a, and a first-layer central hole 121d formed across the M-axis and sandwiched between the two first-layer magnet storage holes 121. The first flux barrier band 120x is formed so that the circumferential center as a whole is convex radially inward. First-layer center bridges 121a are formed between the first-layer central hole 121d and each of the two first-layer magnet storage holes 121.

[0030] The second flux barrier band 120y has two second-layer magnet storage holes that respectively accommodate two second-layer outer magnets 132a and two second-layer inner magnets 132b. A second-layer center bridge 122a is formed between the two second-layer magnet storage holes 122. The second flux barrier band 120y is also formed so that the circumferential center is convex toward the radially inward direction. In particular, in the second-layer magnet storage holes 122, the radially inner side of the second flux barrier band 120y is formed so that the angle between the radially inner portion and the M-axis is larger than the angle between the radially outer portion and the M-axis, i.e., the radially inner portion is bent toward the M-axis, so that the magnetic path that generates reluctance torque becomes smoother.

[0031] 4, which will be referred to later, the partial shapes of the flux barriers, including the presence and position of first-layer outer flux barriers 121c, 121f and second-layer outer flux barriers 122c, 122f (FIG. 4) on the outer peripheral surface 120s of the rotor core 120, are not necessarily symmetrical with respect to the M-axis. The circumferential sides of the magnetic poles are called R-axes, and the geometric center line that is the circumferential center of the two R-axes is called the M-axis. However, the d-axis, which is the electrical center of the magnetic poles, and the q-axis, which is the boundary between the electrical magnetic poles, may deviate from the M-axis and R-axis, respectively.

[0032] As a result of the shape of the multiple flux barrier bands and the arrangement of the permanent magnets 130 described above, the first flux barrier band 120x is arranged with a mixture of first layer first magnets 131a, which are heavy rare earth magnets, and first layer central magnets 131b, which are rare earth magnets.

[0033] As a result of the first flux barrier band 120x having a convex shape extending radially inward and the first layer central magnet 131b being arranged in the center of the first flux barrier band 120x, the first layer central magnet 131b, which is a rare earth magnet, is arranged radially inward of the first layer first magnet 131a, which is a heavy rare earth magnet.

[0034] Similarly, as a result of the second flux barrier band 120y having a convex shape extending radially inward and the second layer inner magnet 132b being arranged on the side of the second flux barrier band 120y closer to the M axis, the second layer inner magnet 132b, which is a rare earth magnet, is arranged radially inward of the second layer first magnet 132a, which is a heavy rare earth magnet.

[0035] The first flux barrier band 120x and the second flux barrier band 120y each contain a mixture of heavy rare earth magnets and rare earth magnets. Considering the volume ratio of the permanent magnets 130 in each flux barrier band to the total volume, the volume ratio of the second flux barrier band 120y is larger than the volume ratio of the first flux barrier band 120x.

[0036] Regarding the thickness of the rare earth magnets, it is desirable to make them thicker from the viewpoint of demagnetization resistance. On the other hand, from the viewpoint of reluctance torque, making them infinitely thicker is not desirable in terms of ensuring the width of the magnetic path adjacent to the magnets. If the thickness in the magnetization direction of the first layer central magnet 131b and the two second layer inner magnets 132b, which are rare earth magnets, is Tb and the coercivity is Hcjb, and the thickness in the magnetization direction of the first layer magnet 131a and the two second layer outer magnets 132a, which are heavy rare earth magnets, is Ta and the coercivity is Hcja, then the thickness Tb of the rare earth magnets is determined to satisfy the following formula (1): Ta<Tb<Ta×(Hcja / Hcjb) (1)

[0037] If the demagnetizing field due to the armature reaction of the stator winding 15 were to act uniformly on the rare earth magnets and heavy rare earth magnets, the demagnetization resistance would be the product of the coercivity and the thickness, so the thickness of the rare earth magnets must be determined so that this product is equivalent to that of the heavy rare earth magnets. However, in this embodiment, when heavy rare earth magnets and rare earth magnets are embedded in the same flux barrier band, the rare earth magnets are located radially inward of the heavy rare earth magnets, so the demagnetizing field is reduced. Therefore, the demagnetization resistance required of the rare earth magnets is smaller than this product. For the above reasons, it is desirable to appropriately set the thickness of the rare earth magnets within the range of formula (1).

[0038] <First Modification of First Embodiment> FIG. 3 is a partial cross-sectional view showing the configuration of a rotating electrical machine 1 according to a first modification of the first embodiment.

[0039] The first-layer magnet storage hole 121 communicates with the outer peripheral surface 120s via a first-layer outer flux barrier 121c and has a first-layer inner storage hole bridge 121b. The second-layer magnet storage hole 122 communicates with the outer peripheral surface 120s via a second-layer outer flux barrier 122c and has a second-layer inner storage hole bridge 122b. Other than this, the second embodiment is the same as the first embodiment.

[0040] By forming the first-layer outer flux barrier 121c and the second-layer outer flux barrier 122c, respectively, and eliminating the top bridges on the outer peripheral surfaces 120s of the first-layer magnet storage holes 121 and the second-layer magnet storage holes 122, i.e., the bridges along the outer peripheral surfaces 120s, leakage magnetic flux can be reduced, and a second-layer storage hole bridge 122b is added near the radial center of the flux barrier band. In this configuration, compared to the configuration shown in FIG. 2, centrifugal force acting on the permanent magnets 130 and the rotor core 120 can be more easily supported in the longitudinal direction of the bridge. Since support by axial force generally provides greater strength than bending, this first modified example improves mechanical strength while suppressing an increase in the width of the center bridges, such as the first-layer center bridge 121a and the second-layer center bridge 122a. Note that simply increasing the thickness of the center bridges to improve mechanical strength is not desirable because it significantly reduces performance due to increased short-circuit magnetic flux to the center bridges.

[0041] Note that changing from heavy rare earth magnets to thicker rare earth magnets increases the total weight. Therefore, the centrifugal force acting on these permanent magnets 130 increases, necessitating measures to improve mechanical strength. Therefore, as mentioned above, by adopting a configuration that makes it easier to support centrifugal force in the longitudinal direction of the bridge, excluding the top bridge, the disadvantage of the increased weight of the permanent magnets 130 can be eliminated.

[0042] <Second Modification of First Embodiment> Fig. 4 is a partial cross-sectional view showing the configuration of a rotating electric machine 1 according to a second modification of the first embodiment. This embodiment is a modification of the first modification. That is, as shown in Fig. 4, the circumferential positions of the first-layer outer flux barriers 121c, 121f and the second-layer outer flux barriers 122c, 122f may be shifted in the same direction compared to the example shown in Fig. 3. As shown in this second modification, the rotor core 120 in each magnetic pole 101 may not be symmetrical about the M-axis.

[0043] <Explanation of Effects> The rotor 100 according to this embodiment and its modified examples configured as described above provides the following effects.

[0044] (1) By placing the rare earth magnet that does not contain heavy rare earth elements closer to the M axis and making it thicker in the magnetization direction, it is possible to compensate for the decrease in coercivity due to the absence of heavy rare earth elements and maintain demagnetization resistance.

[0045] (2) Each flux barrier band is convex radially inward, and since the rare earth magnet that is thick in the magnetization direction is located closer to the M-axis, i.e., toward the center in the circumferential direction, each flux barrier band has a shape that is thick on the radially inner side and thin on the radially outer side. As a result, the magnetic path shape within rotor core 120, whose shape is determined by the arrangement of flux barrier bands 120x, 120y, is appropriately formed, making it possible to maintain high reluctance torque.

[0046] Unlike the present embodiment, if rare earth magnets that do not contain heavy rare earth elements were placed on the outer periphery of the flux barrier band, the thickness in the magnetization direction would need to be significantly increased to maintain demagnetization resistance. In this case, the magnetic path adjacent to the flux barrier band in the rotor core 120 would be compressed, reducing reluctance torque. Furthermore, to ensure the width of the magnetic path, the thickness of the rare earth magnet needs to be limited. On the other hand, when the present embodiment is applied, by placing the rare earth magnets on the inner periphery of the flux barrier band, it is possible to replace some of the heavy rare earth magnets with rare earth magnets while simultaneously ensuring both demagnetization resistance and reluctance torque.

[0047] (3) Compared to using ferrite magnets, by using at least rare earth magnets for all of the permanent magnets 130, the residual magnetization is maintained at the same level, so the amount of magnetic flux can be maintained and a high magnetic torque can be maintained.

[0048] (4) The closer to the outer peripheral surface 120s, the higher the magnetic flux density from the stator winding 15, and therefore the greater the magnetic force in the demagnetization direction due to armature reaction. For this reason, by arranging the multiple-layer flux barrier band so that the ratio of rare earth magnets is higher the closer to the inner diameter of the layers, it is possible to increase the ratio of rare earth magnets that do not contain heavy rare earths in the entire motor while maintaining demagnetization resistance and torque performance.

[0049] Second Embodiment FIG. 5 is a partial cross-sectional view showing the configuration of a rotating electrical machine 1a according to a second embodiment.

[0050] The rotor 100a of this embodiment is a modification of the first embodiment, and does not have the first-layer central hole 121d and the first-layer central magnet 131b housed therein, which are included in the first flux barrier band 120x of the first embodiment.

[0051] The arrangement of the first layer magnets 131 and second layer outer magnets 132a, which are heavy rare earth magnets, and the second layer inner magnets 132b, which are rare earth magnets, is almost the same as in the first embodiment, but the longitudinal dimension of the first layer magnets 131 and the longitudinal dimension of the second layer outer magnets 132a, which are also heavy rare earth magnets, are different. Here, the longitudinal dimension refers to the direction perpendicular to the magnetization direction.

[0052] In this regard, similar performance can be ensured by longitudinally arranging the same magnets as the first layer magnets 131 to form the second layer outer magnets 132a. Alternatively, the first layer magnets 131 and the second layer outer magnets 132a may each be an arrangement of multiple unit magnets of the same size.

[0053] <Modification of Second Embodiment> FIG. 6 is a partial cross-sectional view showing the configuration of a rotating electrical machine 1a according to a modification of the second embodiment.

[0054] The first layer magnet storage hole 121 is connected to the outer peripheral surface 120s via a first layer outer flux barrier 121c and has a bridge 121b within the first layer storage hole, and the second layer magnet storage hole 122 is connected to the outer peripheral surface 120s via a second layer outer flux barrier 122c and has a bridge 122b within the second layer storage hole, and the effects thereof are also the same as those of the first variant of the first embodiment.

[0055] In this way, the second embodiment can also be modified to have a configuration that provides the same effects as the first embodiment.

[0056] 7 is a partial cross-sectional view showing the configuration of a rotating electrical machine 1b according to a third embodiment. This embodiment is a modification of the first embodiment.

[0057] In this embodiment, three flux barrier bands, namely, a first flux barrier band 120x, a second flux barrier band 120y, and a third flux barrier band 120z, are formed on the rotor core 120 of the rotor 100b. In this embodiment, the rotor core 120 is symmetrical about the M-axis in each magnetic pole 101, but is not limited to being symmetrical.

[0058] On the other hand, the permanent magnet 130 consists of a first layer magnet 131, a second layer outer magnet 132a, a second layer inner magnet 132b, a third layer outer magnet 133a, and a third layer inner magnet 133b, each of which is arranged symmetrically about the M axis in each magnetic pole 101.

[0059] The first flux barrier band 120x has two first-layer magnet storage holes 121 and a first-layer center bridge 121a that straddles the M axis between the two first-layer magnet storage holes 121. Each of the two first-layer magnet storage holes 121 houses a first-layer magnet 131, which is a heavy rare-earth magnet.

[0060] The second flux barrier band 120y has two second-layer magnet storage holes 122 and a second-layer center bridge 122a that straddles the M-axis between the two second-layer magnet storage holes 122. Each of the two second-layer magnet storage holes 122 houses a second-layer outer magnet 132a, which is a heavy rare-earth magnet, and a second-layer inner magnet 132b, which is a rare-earth magnet.

[0061] The third flux barrier band 120z has two third-layer magnet storage holes 123 and a third-layer center bridge 123a that straddles the M axis between the two third-layer magnet storage holes 123. Each of the two third-layer magnet storage holes 123 houses a third-layer outer magnet 133a and a third-layer inner magnet 133b, which are rare earth magnets.

[0062] That is, the radially outer first flux barrier band 120x contains only the first layer magnet 131, which is a heavy rare earth magnet, the second flux barrier band 120y contains both the second layer outer magnet 132a, which is a heavy rare earth magnet, and the second layer inner magnet 132b, which is a rare earth magnet, and the third flux barrier band 120z contains the third layer outer magnet 133a and the third layer inner magnet 133b, which are heavy rare earth magnets.

[0063] In this way, the more inward the flux barrier band, the smaller the volume proportion occupied by the heavy rare earth magnets, and instead the larger the volume proportion occupied by the rare earth magnets.

[0064] <Modification of the Third Embodiment> Fig. 8 is a partial cross-sectional view showing the configuration of a rotating electrical machine lb according to a modification of the third embodiment. This embodiment is a modification of the third embodiment.

[0065] The second-layer magnet storage hole 122 is connected to the outer peripheral surface 120s via a second-layer outer flux barrier 122c and has a second-layer inner storage hole bridge 122b. The third-layer magnet storage hole 123 is connected to the outer peripheral surface 120s via a third-layer outer flux barrier 123c and has a third-layer inner storage hole bridge 123b. Other than this, the third embodiment is the same as the third embodiment.

[0066] By forming a second layer outer flux barrier 122c and a third layer outer flux barrier 123c, respectively, and removing the top bridge on the outer surface 120s side of the second layer magnet storage hole 122 and the third layer magnet storage hole 123, leakage magnetic flux can be reduced.

[0067] On the other hand, removing the top bridge increases the tensile force applied to the second-layer center bridge 122a and the third-layer center bridge 123a due to centrifugal force. By providing the second-layer inner-hole bridge 122b and the third-layer inner-hole bridge 123b, the load on the second-layer center bridge 122a and the third-layer center bridge 123a can be appropriately shared and reduced.

[0068] However, replacing the heavy rare earth magnet with a rare earth magnet increases the total weight. Therefore, even if the top bridge is not removed, i.e., in the case of the third embodiment, providing one or both of the second layer housing hole bridge 122b and the third layer housing hole bridge 123b has the effect of ensuring structural strength, just like the first embodiment.

[0069] <Explanation of Effects> The rotor 100b according to this embodiment and its modified examples configured as described above has one more flux barrier band than the first embodiment, but it can achieve the same effects as those described in the first embodiment.

[0070] According to the embodiments described above, it is possible to provide a rotor and a rotating electrical machine that can reduce the amount of heavy rare earth elements used while maintaining performance.

[0071] [Other Embodiments] Although the embodiments of the present invention have been described above, they are presented as examples and are not intended to limit the scope of the invention. Furthermore, features of each embodiment may be combined. Furthermore, the embodiments may be implemented in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. The embodiments and their modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims.

[0072] 1...rotating electric machine, 5...gap, 10...stator, 11...stator core, 11x...inner peripheral surface, 12...stator teeth, 13...stator slot, 15...stator winding, 21...bearing, 22...bearing bracket, 23...frame, 30...rotor, 31...outer magnet, 32...inner magnet, 33...rotor core, 33a...outer storage hole, 33b...inner storage hole, 100, 100a, 100b...rotor, 101...magnetic pole, 110...rotor shaft, 120...rotor core, 120m...magnet storage hole, 120s...outer peripheral surface, 120x...first flux barrier band, 120y...second flux barrier band, 120z...third flux barrier band, 121...first layer magnet storage hole, 121a...first layer sensor

[0033] Super bridge, 121b...first layer storage hole inner bridge, 121c, 121f...first layer outer flux barrier, 121d...first layer central hole, 122...second layer magnet storage hole, 122a...second layer center bridge, 122b...second layer storage hole inner bridge, 122c, 122f...second layer outer flux barrier, 123...third layer magnet storage hole, 123a...third layer center bridge, 123b...third layer storage hole inner bridge, 123c...third layer outer flux barrier, 124...first layer central flux barrier, 130...permanent magnet, 131...first layer magnet, 132a...second layer outer magnet, 132b...second layer inner magnet, 133a...third layer outer magnet, 133b...third layer inner magnet, CL...rotation center axis

Claims

1. A rotor comprising: a rotor shaft extending in the direction of the central axis of rotation; a rotor core attached to the radial outside of the rotor shaft, with a plurality of flux barrier bands formed on each magnetic pole at radial intervals, the flux barrier bands including bridges and non-magnetic regions that are approximately convex toward the central axis of rotation; and a plurality of permanent magnets in each of the plurality of flux barrier bands, the plurality of permanent magnets including at least one of a rare earth magnet that does not contain a heavy rare earth element and a heavy rare earth magnet that contains a heavy rare earth element, and which are arranged in line symmetry with respect to an M-axis extending from the central axis of rotation on a cross section perpendicular to the central axis of rotation, wherein when viewed from the flux barrier band in which both the rare earth magnets and the heavy rare earth magnets are housed, the rare earth magnets have a greater thickness in the magnetization direction than the heavy rare earth magnets and are arranged on the side closer to the M-axis.

2. A rotor as described in claim 1, characterized in that the ratio of the volume of the rare earth magnet to the total volume of the permanent magnets in the flux barrier band is greater the further radially inward the permanent magnets are in the flux barrier band.

3. A rotor as described in claim 1, characterized in that an outer flux barrier is formed in any of the magnet storage holes that house the permanent magnets, connecting the magnet storage holes to the outer peripheral surface of the rotor core, and a bridge is provided within the magnet storage hole.

4. A rotor as claimed in claim 1, characterized in that the coercive force of said rare earth magnet is less than two-thirds of the coercive force of said heavy rare earth magnet.

5. A rotor as described in claim 1, characterized in that, for the heavy rare earth magnet and the rare earth magnet arranged in the same flux barrier band, the product of the thickness in the magnetization direction and the coercive force of the heavy rare earth magnet is greater than the product of the thickness in the magnetization direction and the coercive force of the rare earth magnet.

6. A rotating electric machine comprising: a rotor according to any one of claims 1 to 5; a stator core arranged radially outside said rotor core so as to surround said rotor core; and a stator having a stator winding wound around said stator core.

Images