Rotary electric machine

Abstract

To suppress increase in eddy current loss of a permanent magnet, suppress rise in temperature of the permanent magnet, and make irreversible demagnetization less likely to occur in a rotary electric machine having a multipolar Halbach magnet arrangement.SOLUTION: A rotary electric machine includes a stator in which a coil is wound around a stator core, and a rotor that faces the stator via a predetermined gap and in which a spoke magnet 211 magnetized in a circumferential direction and a main pole magnet magnetized in a radial direction are embedded in a rotor core. Each of the spoke magnet 211 and a main pole magnet 212 is divided into a plurality of magnet pieces 2111, 2121 in at least one of an axial direction, a circumferential direction, and a radial direction of the rotor. A length A of the magnet piece 2111 of the spoke magnet 211 in a dividing direction is shorter than a length of a magnet piece 2121 of the main pole magnet 212 in the dividing direction.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] The recent trend toward reducing CO2 emissions has led to strong demands for CO2 emission regulations in countries around the world toward the realization of a zero-carbon society. Electrification, which does not emit CO2 during operation, is being actively promoted as an alternative to CO2-emitting fossil-fuel engines. In particular, in the field of air mobility, such as aircraft and electric vertical takeoff and landing (eVTOL) vehicles, increasing range and payload requires reducing the weight of rotating electrical machines such as electric motors and generators while increasing their output and torque—that is, increasing power density and torque density. Known methods for reducing the weight of rotating electrical machines include increasing the number of poles and thinning the stator and rotor radially. Another known method for increasing torque is the Halbach magnet arrangement, which combines a main pole magnet located on the rotor's d-axis with a spoke magnet located on the q-axis. Another known method for increasing output is increasing the rotating speed and wattage of the rotating electrical machine.

[0003] For example, Patent Document 1 describes a technology for a rotating electric machine in which the number of poles is increased, the wall thickness is reduced in the radial direction to reduce weight, and a Halbach magnet arrangement is used to increase torque. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2023 / 286606 Summary of the Invention [Problem to be solved by the invention]

[0005] When the rotational speed of the rotating electric machine of Patent Document 1 is increased to increase the output, the fundamental frequency of the current increases due to the multiple poles, which increases the iron loss in the core and the eddy current loss in the magnets. In particular, when the eddy current loss in the permanent magnets arranged in the rotor increases, the temperature of the permanent magnets rises, making them more susceptible to irreversible demagnetization, which is a problem.

[0006] An object of the present invention is to suppress an increase in eddy current loss in permanent magnets and a rise in temperature of permanent magnets in a rotating electrical machine with a multi-pole Halbach magnet arrangement, thereby making irreversible demagnetization less likely to occur. [Means for solving the problem]

[0007] In order to achieve the above object, the rotating electric machine of the present invention comprises: A rotating electric machine comprising: a stator having a stator core around which a coil is wound; and a rotor facing the stator across a predetermined gap, the rotor core including circumferentially magnetized spoke magnets and radially magnetized main pole magnets embedded therein, The spoke magnets and the main pole magnets are each divided into a plurality of magnet pieces in at least one of the axial direction, circumferential direction, and radial direction of the rotor, The length of the spoke magnet in the direction in which the magnet pieces are divided is shorter than the length of the main pole magnet in the direction in which the magnet pieces are divided. Other aspects of the present invention will be described in the following embodiments. [Effects of the Invention]

[0008] According to the present invention, in a rotating electrical machine with a multi-pole Halbach magnet arrangement, it is possible to suppress an increase in eddy current loss in a permanent magnet, suppress an increase in the temperature of the permanent magnet, and make it difficult for irreversible demagnetization to occur. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a rotating electric machine 100 according to a first embodiment. [Figure 2] 1 is a cross-sectional view of a stator 1 and a rotor 2 of a rotating electric machine 100 according to a first embodiment. [Figure 3] 2 is a perspective view of a permanent magnet 21 of the rotating electric machine 100 according to the first embodiment. FIG. [Figure 4] 1 shows the distribution of eddy current vectors flowing in the permanent magnet 21 of the rotating electric machine 100 according to the first embodiment. [Figure 5] 10 shows the distribution of eddy current vectors flowing in a permanent magnet 21 of a rotating electric machine in a comparative example. [Figure 6] 10 is a comparison of eddy current loss occurring in permanent magnet 21 of the rotating electric machine in the first embodiment and the comparative example. [Figure 7] FIG. 10 is a perspective view of a permanent magnet 21 of a rotating electric machine 100 according to a second embodiment. [Figure 8] FIG. 10 is a perspective view of a permanent magnet 21 of a rotating electric machine 100 according to a third embodiment. [Figure 9] FIG. 10 is a perspective view of a permanent magnet 21 of a rotating electric machine 100 according to a fourth embodiment. [Figure 10] FIG. 10 is a perspective view of a permanent magnet 21 of a rotating electric machine 100 according to a fifth embodiment. [Figure 11] 10 is a cross-sectional view of a stator 1 and a rotor 2 of a rotating electric machine 100 according to a sixth embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In multiple embodiments and modified examples of each embodiment, similar components are designated by the same reference numerals, and redundant description will be omitted.

[0011] [Example 1] A rotating electric machine according to a first embodiment of the present invention will be described with reference to Figures 1 to 6. Figure 1 is a cross-sectional view of a rotating electric machine 100 according to the first embodiment.

[0012] [Configuration of the rotating electric machine 100] As shown in FIG. 1, a rotating electric machine 100 includes a stator 1, a rotor 2 disposed on the inner periphery of the stator 1 via an air gap (gap) 3, a housing 10 that holds the stator 1, a shaft 20 that holds the rotor 2, and a bearing 30 that holds the shaft 20 while rotating relative to the housing 10. The rotor 2 is provided with permanent magnets 21 that serve as field poles, a rotor core 22 that holds the permanent magnets 21, and a cylindrical rotor core holder 23. The shaft 20 is fixed into a through hole in the rotor core holder 23 by press-fitting or shrink-fitting. The stator 1 is provided with a coil 11 and a stator core 12. Lead wires 41 extending from an inverter 40 enter the rotating electric machine 100 and are connected to the coil 11 via a connection 13. Three-phase alternating current is passed through the coil 11 from the inverter 40 to form a rotating magnetic field, which generates torque through interaction with the permanent magnets 21 that serve as field poles of the rotor 2. The configuration of the rotating electric machine 100 described above is also commonly applied to the embodiments described later. The rotating electric machine 100 according to the present invention can be applied to either an inner rotor type in which the rotor 2 is rotatably supported on the inner periphery of the stator 1, or an outer rotor type in which the rotor 2 is rotatably supported on the outer periphery of the stator 1.

[0013] <Configuration of Stator 1 and Rotor 2> Fig. 2 is a cross-sectional view of the stator 1 and rotor 2 according to the first embodiment. Fig. 2 shows a cross section perpendicular to the axis of rotation.

[0014] The stator 1 has a central axis 1ax (see FIG. 1) that coincides with the rotational axis 2ax (see FIG. 1) of the rotor 2, and includes a stator core 12 formed by laminating multiple core sheets, and a coil 11 formed by winding a copper or aluminum conductor. In this specification, the direction along the rotational axis 2ax and the central axis 1ax is referred to as the "axial direction," the direction of rotation about this axial direction is referred to as the "circumferential direction," and the direction perpendicular to the rotational axis 2ax and the central axis 1ax is referred to as the "radial direction."

[0015] The stator core 12 includes a circular stator back yoke 121, a plurality of teeth 122 connected to the stator back yoke 121 and provided on the radial air gap 3 side, and slots 123 provided between adjacent teeth 122 in the circumferential direction. The coils 11 are wound around the teeth 122 and housed in the slots 123. The stator core 12 may be formed from an integrally molded solid member. Alternatively, it may be formed by compression molding a powder magnetic material such as a dust core, or may be formed from an amorphous metal or a nanocrystalline material.

[0016] The rotor 2 includes a rotor core 22 and permanent magnets 21 inserted into magnet holes formed in the rotor core 22. The rotor core 22 is formed by laminating multiple core sheets. The rotor core 22 may be formed as an integrally molded solid member. It may also be formed by compression molding a powder magnetic material such as a dust core, or may be formed from an amorphous metal or nanocrystalline material. The permanent magnet 21 includes spoke magnets 211 and a main pole magnet 212. The spoke magnets 211 have a cross section that is long in the radial direction and are magnetized circumferentially. The main pole magnets 212 have a cross section that is long in the circumferential direction and are magnetized radially. In Figure 2, the magnetization directions of the spoke magnets 211 and the main pole magnet 212 are indicated by arrows.

[0017] The main pole magnet 212 is disposed at a position radially farther from the air gap 3 than the spoke magnets 211. All of the permanent magnets 21 are made of rare earth sintered magnets. Of the rotor core 22, the region located closer to the air gap 3 in the radial direction than the main pole magnet 212 is called the main core 221, and the region located on the radially opposite side of the air gap 3 from the main pole magnet 212 is called the back core 222.

[0018] The back core 222 serves to form a path for magnetic flux from one pole of the rotor 2 to the adjacent pole in the circumferential direction, and to improve the mechanical strength of the rotor core 22. The main core 221 functions to increase the gap magnetic flux density by concentrating the magnetic flux of the main pole magnet 212 and the magnetic flux of the spoke magnets 211. This enables the torque density of the rotating electric machine 100 to be increased.

[0019] Between the spoke magnets 211 and the main pole magnets 212, there is formed an inter-magnet bridge 223, which is a narrow portion of the rotor core 22. Because the inter-magnet bridge 223 serves as a path for leakage magnetic flux that short-circuits the magnetic flux of the permanent magnets, it is desirable to form the inter-magnet bridge 223 with a small circumferential width. On the other hand, the inter-magnet bridge 223 is also a portion where large stress occurs due to the load of centrifugal force and electromagnetic force acting on the rotor 2. For this reason, when designing the inter-magnet bridge 223, the width of the inter-magnet bridge 223 is determined by balancing magnetic properties such as torque with mechanical strength.

[0020] Additionally, claws 224 are formed between the spoke magnets 211 and the air gap 3, extending in the circumferential direction from the tip of the main core 221 on the air gap 3 side. The claws 224 have the role of preventing the spoke magnets 211 from scattering from the rotor core 22 due to the load of centrifugal force or electromagnetic force. On the other hand, since the claws 224 become a path for leakage magnetic flux that short-circuits the magnetic flux generated from the permanent magnets 21, it is desirable that the radial width of the claws 224 is small and that they are spaced apart from adjacent claws 224 in the circumferential direction. For this reason, the width and circumferential length of the claws 224 are determined by balancing magnetic properties such as torque with mechanical strength.

[0021] FIG. 3 is a perspective view of the permanent magnet 21 of the rotating electric machine 100 according to the first embodiment. The spoke magnet 211 is divided into multiple spoke magnet pieces 2111 in the axial direction, which are bonded together with an adhesive. The main pole magnet 212 is divided into multiple main pole magnet pieces 2121 in the axial direction, which are bonded together with an adhesive. Here, if the axial length of the spoke magnet piece 2111 is A and the axial length of the main pole magnet piece 2121 is B, then the following relationship exists between A and B:

[0022] A That is, the axial length A of the divided spoke magnet piece 2111 is shorter than the axial length B of the main pole magnet piece 2121 .

[0023] ​Fig. 4 shows the distribution of eddy current vectors flowing in the permanent magnet 21 of the rotating electric machine 100 according to the first embodiment. Fig. 5 shows the distribution of eddy current vectors flowing in the permanent magnet 21 of a rotating electric machine in a comparative example. In the comparative example, eddy currents flow as shown by the arrows in Figure 5. In this case, in the comparative example, more eddy currents flow in the spoke magnets 211 than in the main pole magnets 212. In particular, large eddy current loops are formed in the axial direction of the spoke magnets 211, and particularly large eddy currents flow in the upper radial corners close to the air gap.

[0024] On the other hand, in Figure 4, where the permanent magnet 21 is divided in the axial direction, adhesive is interposed between the divided spoke magnet pieces 2111, so each of the divided spoke magnet pieces 2111 is electrically insulated. As a result, the eddy current loop closes within each spoke magnet piece 2111, increasing the electrical resistance to the eddy current loop compared to when the magnet is not divided, and significantly reducing the eddy current.

[0025] FIG. 6 shows a comparison of eddy current loss occurring in the permanent magnet 21 of the rotating electrical machine in the first embodiment and the comparative example. When the main pole magnet 212 and the spoke magnet 211 are not divided, the eddy current loss is larger in the spoke magnet 211 than in the main pole magnet 212, and the eddy current loss in the spoke magnet 211 is particularly dominant.Therefore, by making the axial length A of the spoke magnet piece 2111 smaller than the axial length B of the main pole magnet piece 2121, the large eddy current loss that is dominantly generated in the spoke magnet 211 can be effectively reduced.

[0026] On the other hand, since the eddy current loss of the main pole magnet 212 is relatively small, the axial length B does not need to be as small as that of the spoke magnet 211.

[0027] As a result of the above, by focusing on reducing the eddy current loss that occurs in the plane along the axial direction of the spoke magnet 211, it is possible to suppress the temperature rise in the permanent magnet 21 caused by eddy current loss, improve the torque characteristics of the rotating electric machine 100, and suppress irreversible demagnetization of the permanent magnet 21.

[0028] [Example 2] A rotating electrical machine 100 according to a second embodiment of the present invention will be described with reference to Fig. 7. The second embodiment can be configured in the same way as the first embodiment except for the following points. The following description will focus on the differences from the first embodiment.

[0029] FIG. 7 is a perspective view of a permanent magnet 21 of a rotating electric machine 100 according to the second embodiment. In this embodiment, the spoke magnet 211a is divided into multiple spoke magnet pieces 2111a in the circumferential direction, and each of the multiple spoke magnet pieces 2111a is bonded with an adhesive. Because adhesive is interposed between the divided spoke magnet pieces 2111a, each of the divided spoke magnet pieces 2111a is electrically insulated. Here, if the circumferential length of the spoke magnet piece 2111a is C and the circumferential length of the main pole magnet 212 is D, the following relationship exists between C and D:

[0030] C <D …(2) That is, the circumferential length C of the divided spoke magnet pieces 2111 a is shorter than the circumferential length D of the main pole magnet 212 .

[0031] By making the circumferential length C of the spoke magnet pieces 2111a smaller than the circumferential length D of the main pole magnet 212, the eddy current loss occurring in the spoke magnets 211a can be effectively reduced.

[0032] On the other hand, since the eddy current loss of the main pole magnet 212 is relatively small, it is not necessary to make the circumferential length D as small as that of the spoke magnet pieces 2111a of the spoke magnets 211.

[0033] As a result of the above, by focusing on reducing the eddy current loss that occurs in the plane along the circumferential and radial directions of the spoke magnet 211, it is possible to suppress the temperature rise of the permanent magnet 21 caused by eddy current loss, improve the torque characteristics of the rotating electric machine 100, and suppress irreversible demagnetization of the permanent magnet 21.

[0034] In this embodiment, as in the first embodiment, the spoke magnets 211 and the main pole magnets 212 are divided into a plurality of magnet pieces in the axial direction, but they may be divided only in the circumferential direction without being divided in the axial direction.

[0035] [Example 3] A rotating electric machine 100 according to a third embodiment of the present invention will be described with reference to Fig. 8. The third embodiment can be configured similarly to the first and second embodiments except for the following points. The following description will focus on the differences from the first and second embodiments.

[0036] FIG. 8 is a perspective view of a permanent magnet 21 of a rotating electric machine 100 according to the third embodiment. The spoke magnet 211b of this embodiment is divided into multiple spoke magnet pieces 2111b in the radial direction compared to the spoke magnet 211a of the second embodiment, and each of the divided spoke magnet pieces 2111b in the radial and circumferential directions is bonded with an adhesive. That is, in this embodiment, the spoke magnet pieces 2111a of the second embodiment, which were divided in the circumferential direction, are further divided in the radial direction. Because adhesive is interposed between the divided spoke magnet pieces 2111b, each of the divided spoke magnet pieces 2111b is electrically insulated. Here, if the radial length of the spoke magnet piece 2111b is E and the radial length of the main pole magnet 212 is F, the following relationship exists between E and F:

[0037] E <F …(3) That is, the radial length E of the divided spoke magnet pieces 2111b is shorter than the radial length F of the main pole magnet 212.

[0038] By making the radial length E of the spoke magnet pieces 2111b smaller than the radial length F of the main pole magnet 212, the eddy current loss occurring in the spoke magnets 211b can be effectively reduced.

[0039] On the other hand, since the eddy current loss of the main pole magnet 212 is relatively small, it is not necessary to make the radial length F as small as that of the spoke magnet piece 2111b of the spoke magnet 211.

[0040] As a result of the above, by focusing on reducing eddy current loss that occurs in planes along the circumferential and radial directions of the spoke magnets 211b in particular, it is possible to suppress the temperature rise in the permanent magnets 21 that is caused by eddy current loss, improve the torque characteristics of the rotating electric machine 100, and suppress irreversible demagnetization of the permanent magnets 21. In particular, the spoke magnets 211b of this embodiment are divided so that their radial length is smaller than that of the spoke magnets 211a of the second embodiment, which makes it possible to reduce eddy currents that occur in planes along the circumferential and radial directions.

[0041] In this embodiment, the spoke magnet 211 and main pole magnet 212 are divided into multiple magnet pieces in the axial direction as in the first embodiment, and the spoke magnet 211 is divided into multiple magnet pieces in the circumferential direction as in the second embodiment, but it is also possible to divide it only in the radial direction without dividing it in the axial and circumferential directions. Alternatively, the spoke magnet 211 may be divided into multiple magnet pieces in the radial direction and also divided in either the axial or circumferential direction.

[0042] [Example 4] A rotating electric machine 100 according to a fourth embodiment of the present invention will be described with reference to Fig. 9. The fourth embodiment can be configured similarly to the first to third embodiments except for the following points. The following description will focus on the differences from the first to third embodiments.

[0043] FIG. 9 is a perspective view of a permanent magnet 21 of a rotating electric machine 100 according to the fourth embodiment. Compared to the spoke magnet 211a of the second embodiment, the spoke magnet 211c of this embodiment is divided radially into multiple spoke magnet pieces (first spoke magnet pieces) 2111b and spoke magnet pieces (second spoke magnet pieces) 2111c, and the divided spoke magnet pieces 2111b and 2111c in the radial and circumferential directions are bonded together with an adhesive. Here, the spoke magnet pieces 2111c are located on the radial air gap side and have a radial length G, and the spoke magnet pieces 2111b are located on the radial opposite side of the air gap 3 (see FIG. 2) and have a radial length E. There is the following relationship between G and E: The radial length of the spoke magnet piece 2111c located on the radial air gap 3 side is shorter than the radial length of the spoke magnet piece 2111b located on the radial opposite side of the air gap.

[0044] G <E …(4) That is, the spoke magnet pieces 2111c of this embodiment are obtained by dividing the spoke magnet pieces 2111b of the third embodiment into a plurality of smaller pieces in the radial direction on the radial side of the air gap 3. For this reason, the spoke magnet 211c of this embodiment is divided into a plurality of spoke magnet pieces 2111b and 2111c in the radial direction such that the radial length G of the spoke magnet piece 2111c on the radially inner side is smaller than the radial length E of the spoke magnet piece 2111b on the radially outer side.

[0045] In other words, the spoke magnet 211c is divided radially into a first spoke magnet piece 2111b and a second spoke magnet piece 2111c which have different radial lengths, and the second spoke magnet piece 2111c is positioned radially inner than the first spoke magnet piece 2111b and is divided so that its radial length G is smaller than the radial length E of the first spoke magnet piece 2111b.

[0046] By making the radial length of the spoke magnet piece 2111c located on the radial air gap side smaller than the radial length of the spoke magnet piece 2111d located on the opposite radial side from the air gap, the eddy current loss of the spoke magnet 211c that occurs largely on the radial air gap 3 side can be effectively reduced.

[0047] On the other hand, since the eddy current loss of the spoke magnet piece 2111b located radially opposite the air gap 3 is relatively small, there is no need to make the radial length E as small as that of the spoke magnet piece 2111c located radially on the air gap 3 side.

[0048] As a result of the above, by focusing on reducing eddy current loss that occurs in planes along the circumferential and radial directions of the spoke magnets 211c, it is possible to suppress the temperature rise in the permanent magnets 21 caused by eddy current loss, improve the torque characteristics of the rotating electric machine, and suppress irreversible demagnetization of the permanent magnets 21. In particular, the spoke magnets 211c of this embodiment are divided so that their radial length is smaller on the radial air gap 3 side compared to the spoke magnets 211b of the third embodiment, which makes it possible to reduce eddy currents that occur in planes along the circumferential and radial directions on the radial air gap 3 side.

[0049] In this embodiment, the spoke magnet 211 and main pole magnet 212 are divided into multiple magnet pieces in the axial direction as in the first embodiment, and the spoke magnet 211 is divided into multiple magnet pieces in the circumferential direction as in the second embodiment, but it is also possible to divide it only in the radial direction without dividing it in the axial and circumferential directions. Alternatively, the spoke magnet 211 may be divided into multiple magnet pieces in the radial direction, and may also be divided in either the axial or circumferential direction. Alternatively, the multiple first spoke magnet pieces 2111b may be configured as an integrated magnet piece without being divided, and only the second spoke magnet piece 2111c may be provided on the radial air gap 3 side.

[0050] [Example 5] A rotating electric machine 100 according to a fifth embodiment of the present invention will be described with reference to Fig. 10. The fifth embodiment can be configured similarly to the first to fourth embodiments except for the following points. The following description will focus on the differences from the first to fourth embodiments.

[0051] FIG. 10 is a perspective view of a permanent magnet 21 of a rotating electric machine 100 according to a fifth embodiment. Compared to spoke magnet 211a of the second embodiment, spoke magnet 211d of this embodiment is divided radially into a plurality of spoke magnet pieces (first spoke magnet pieces) 2111b and spoke magnet pieces (second spoke magnet pieces) 2111d, and spoke magnet pieces 2111d are further divided into smaller pieces in the circumferential, radial, and axial directions relative to spoke magnet piece 2111b. Spoke magnet pieces 2111b and spoke magnet pieces 2111d divided radially and circumferentially are each bonded with an adhesive.

[0052] Spoke magnet piece 2111d is located on the radial side of air gap 3 (see FIG. 2) relative to spoke magnet piece 2111b, and its circumferential length is I1, radial length is I2, and axial length is I3. Spoke magnet piece 2111b is located on the radially opposite side of air gap 3 relative to spoke magnet piece 2111d, and its circumferential length is J1, radial length is J2, and axial length is J3. Here, the following relationship exists between I1, I2, I3 and J1, J2, and J3. That is, circumferential length I1, radial length I2, and axial length I3 of spoke magnet piece 2111d located on the radial side of air gap 3 are each shorter than circumferential length J1, radial length J2, and axial length J3 of spoke magnet piece 2111b located on the radially opposite side of air gap 3.

[0053] I1 <J1 …(5) I2 <J2 …(6) I3 <J3 …(7) That is, the spoke magnet pieces 2111d of this embodiment are obtained by dividing the spoke magnet pieces 2111c of the fourth embodiment into a plurality of smaller pieces in the circumferential and axial directions on the radial air gap 3 side than the spoke magnet pieces 2111c of the fourth embodiment. Therefore, the spoke magnet 211d of this embodiment is divided radially into a plurality of spoke magnet pieces 2111b and 2111d so that the circumferential length I1 of the spoke magnet piece 2111d on the radially inner side is shorter than the circumferential length J1 of the spoke magnet piece 2111b on the radially outer side. Furthermore, the spoke magnet 211d is divided radially into a plurality of spoke magnet pieces 2111b and 2111d so that the radial length I2 of the spoke magnet piece 2111d on the radially inner side is shorter than the radial length J2 of the spoke magnet piece 2111b on the radially outer side. Furthermore, the spoke magnet 211d is divided radially into multiple spoke magnet pieces 2111b and spoke magnet pieces 2111d so that the axial length I3 of the spoke magnet piece 2111d on the radially inner side is smaller than the axial length J3 of the spoke magnet piece 2111b on the radially outer side.

[0054] In other words, the spoke magnet 211d is divided radially into a first spoke magnet piece 2111b and a second spoke magnet piece 2111d which have different circumferential lengths, and the second spoke magnet piece 2111d is arranged radially inward from the first spoke magnet piece 2111b and is divided so that its circumferential length I1 is smaller than the circumferential length J1 of the first spoke magnet piece 2111b. Furthermore, the spoke magnet 211d is divided radially into a first spoke magnet piece 2111b and a second spoke magnet piece 2111d which have different radial lengths, and the second spoke magnet piece 2111d is arranged radially inward from the first spoke magnet piece 2111b and is divided so that its radial length I2 is smaller than the radial length J2 of the first spoke magnet piece 2111b. Furthermore, the spoke magnet 211d is divided radially into a first spoke magnet piece 2111b and a second spoke magnet piece 2111d, which have different axial lengths, and the second spoke magnet piece 2111d is positioned radially inner than the first spoke magnet piece 2111b and is divided so that its axial length I3 is smaller than the axial length J3 of the first spoke magnet piece 2111b.

[0055] The purpose of this embodiment is to divide the spoke magnets 211d more finely on the radial air gap 3 side (radially inner circumferential side) than on the radially opposite side from the air gap 3 (radially outer circumferential side), and it is sufficient that the second spoke magnet pieces 2111d are divided more finely than the first spoke magnet pieces 2111b in at least one of the circumferential, radial, and axial directions. In this case, if the second spoke magnet pieces 2111d are divided more finely than the first spoke magnet pieces 2111b only in the radial direction, this will have the same configuration as the fourth embodiment. Other configurations can be similar to those of the first to fourth embodiments.

[0056] By making the circumferential length I1, radial length I2 and axial length I3 of the spoke magnet piece 2111d located on the radial side of the air gap 3 smaller than the circumferential length J1, radial length J2 and axial length J3 of the spoke magnet piece 2111b located on the radially opposite side of the air gap 3, the eddy current loss of the spoke magnet 211d that occurs to a large extent on the radial side of the air gap 3 can be effectively reduced.

[0057] On the other hand, the spoke magnet piece 2111b located on the opposite radial side from the air gap 3 has relatively small eddy current loss, so there is no need to make the circumferential length J1, radial length J2 and axial length J3 as small as those of the spoke magnet piece 2111d located on the radial side of the air gap 3.

[0058] As a result of the above, by focusing on reducing the eddy current loss that occurs significantly on the radial air gap 3 side of the spoke magnet 211d, it is possible to suppress the temperature rise of the permanent magnet 21 caused by eddy current loss, improve the torque characteristics of the rotating electric machine 100, and suppress irreversible demagnetization of the permanent magnet 21.

[0059] [Example 6] A rotating electrical machine 100 according to a sixth embodiment of the present invention will be described with reference to Fig. 11. The sixth embodiment can be configured in the same manner as the fifth embodiment except for the following points. The following description will focus on the differences from the fifth embodiment.

[0060] Fig. 11 is a cross-sectional view of the stator 1 and rotor 2 according to the sixth embodiment. Fig. 11 shows a cross section perpendicular to the rotation axis 20 (see Fig. 1). In this embodiment, a magnet holding plate 24 is disposed between the spoke magnet 211d and the air gap 3. The magnet holding plate 24 is disposed so as to cover the surface of the spoke magnet 211d radially facing the air gap 3 and is held by claws 224 extending circumferentially from the tip of the main core 221 facing the air gap 3. The spoke magnet pieces 2111e do not directly receive the reaction force from the claws 224 when centrifugal force or electromagnetic force acts on the spoke magnet 211d, but receive it via the magnet holding plate 24, thereby preventing damage to the spoke magnet pieces 2111e. Furthermore, even if the spoke magnet pieces 2111e separate from the spoke magnet 211d or are chipped due to the load of centrifugal force or electromagnetic force, the magnet holding plate 24 covers the spoke magnet pieces 2111e, preventing them from scattering from the rotor core 22.

[0061] The material of magnet holding plate 24 is preferably a non-magnetic material to prevent leakage of magnetic flux between the magnetic poles. It is also preferably a non-conductive material to prevent the generation of eddy currents within magnet holding plate 24. Magnet holding plate 24 may be made of, for example, a resin material or fiber reinforced plastic (FRP).

[0062] The configuration of this embodiment can be applied to the first to fourth embodiments as well as the fifth embodiment.

[0063] [Variations] The present invention is not limited to the above-described embodiments, and various modifications are possible. The above-described embodiments are provided as examples to facilitate understanding of the present invention, and are not necessarily limited to those including all of the configurations described. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to delete part of the configuration of each embodiment, or to add or replace other configurations. Possible modifications of the above-described embodiments are, for example, as follows.

[0064] (1) In each of the above embodiments, one inverter is connected to one rotating electric machine 100, but in order to increase the redundancy of the rotating electric machine 100, a three-phase double winding or open winding may be used in which multiple inverters are connected.

[0065] (2) The material of the permanent magnet 21 is assumed to be, for example, a rare earth sintered magnet. However, other permanent magnets may also be used, such as rare earth bonded magnets or ferrite magnets made by mixing rare earth magnetic powder such as samarium iron nitrogen magnets or neodymium magnets with an organic binder.

[0066] The rotating electric machine 100 according to the present invention described above has the following features.

[0067] (1) A rotating electric machine 100 including a stator 1 having a coil 11 wound around a stator core 12, and a rotor 2 facing the stator 1 across a predetermined gap 3, in which circumferentially magnetized spoke magnets 211, 211a, 211b, 211c, 211d and a radially magnetized main pole magnet 212 are embedded in the rotor core 22, The spoke magnets 211, 211a, 211b, 211c, 211d and the main pole magnet 212 are each divided into a plurality of magnet pieces 2111, 2111a, 2111b, 2111c, 2111d, 2121 in at least one of the axial, circumferential, and radial directions of the rotor 2, The length of the magnet pieces 2111, 2111a, 2111b, 2111c, and 2111d of the spoke magnet 211 in the division direction is shorter than the length of the magnet piece 2121 of the main pole magnet 212 in the division direction.

[0068] (2) The spoke magnets 211 and the main pole magnets 212 are each divided into a plurality of magnet pieces 2111 and 2121 in the axial direction of the rotor 2. The axial length A of the magnet piece 2111 of the spoke magnet 211 is shorter than the axial length B of the magnet piece 2121 of the main pole magnet 212.

[0069] (3) The spoke magnets 211a are divided into a plurality of magnet pieces 2111a in the circumferential direction of the rotor 2, The circumferential length C of the magnet piece 2111a of the spoke magnet 211a is shorter than the circumferential length D of the magnet piece 2121 of the main pole magnet 212.

[0070] (4) The spoke magnet 211b is divided into a plurality of magnet pieces 2111b in the radial direction of the rotor 2, The radial length E of the magnet piece 2111b of the spoke magnet 211b is shorter than the radial length F of the magnet piece 2121 of the main pole magnet.

[0071] (5)(4) The spoke magnet 211c is divided in the radial direction of the rotor 2 so as to include a first magnet piece 2111b and a second magnet piece 2111c having different radial lengths, Of the magnet pieces 2111b, 2111c of the spoke magnet 211, the radial length G of the second magnet piece 2111c arranged on the side of gap 3 is shorter than the radial length E of the first magnet piece 2111b arranged on the opposite side of gap 3.

[0072] (6)(4) The spoke magnet 211d is divided in the radial direction of the rotor 2 so as to include a first magnet piece 2111b and a second magnet piece 2111d which have different axial lengths, Of the magnet pieces 2111b, 2111d of the spoke magnet 211, the axial length I3 of the second magnet piece 2111d arranged on the side of gap 3 is shorter than the axial length J3 of the first magnet piece 2111b arranged on the opposite side of gap 3.

[0073] (7)(4) The spoke magnet 211d is divided in the radial direction of the rotor 2 so as to include a first magnet piece 2111b and a second magnet piece 2111d which have different circumferential lengths, Of the magnet pieces 2111b, 2111d of the spoke magnet, the circumferential length I1 of the second magnet piece 2111d arranged on the side of gap 3 is shorter than the circumferential length J1 of the first magnet piece 2111b arranged on the opposite side of gap 3.

[0074] (8) The rotor core 22 has a main core 221 located radially closer to the gap 3 than the main pole magnet 212, claw portions 224 extending circumferentially from the tip of the main core 221 on the gap 3 side, and a magnet holding plate 24 arranged between the spoke magnet 211d and the gap 3, The magnet holding plate 24 is held by the claws 224 . [Explanation of symbols]

[0075] 1...stator, 2...rotor, 10...housing, 11...coil, 12...stator core, 13...wiring connection portion, 20...shaft, 21...permanent magnet, 22...rotor core, 23...rotor core holding portion, 24...magnet holding plate, 30...bearing, 40...inverter, 41...lead wire, 100...rotating electric machine, 121...stator back yoke, 122...teeth, 211, 211a, 211b, 211c, 211d...spoke magnet, 212...main pole magnet, 221...main core, 222...back core, 223...inter-magnet bridge, 224...claw portion, 2111, 2111a, 2111b, 2111c, 2111d...spoke magnet piece, 2121...main pole magnet piece.

Claims

1. A rotating electric machine comprising: a stator having a stator core around which a coil is wound; and a rotor facing the stator across a predetermined gap, the rotor core including circumferentially magnetized spoke magnets and radially magnetized main pole magnets embedded therein, The spoke magnets and the main pole magnets are each divided into a plurality of magnet pieces in at least one of the axial direction, circumferential direction, and radial direction of the rotor, A rotating electric machine characterized in that the length of the magnet pieces of the spoke magnets in the division direction is shorter than the length of the magnet pieces of the main pole magnets in the division direction.

2. 2. The rotating electric machine according to claim 1, Each of the spoke magnets and the main pole magnets is divided into a plurality of magnet pieces in the axial direction of the rotor, A rotating electric machine characterized in that the axial length of the magnet pieces of the spoke magnets is shorter than the axial length of the magnet pieces of the main pole magnets.

3. 2. The rotating electric machine according to claim 1, The spoke magnet is divided into a plurality of magnet pieces in the circumferential direction of the rotor, A rotating electric machine characterized in that the circumferential length of the magnet pieces of the spoke magnets is shorter than the circumferential length of the magnet pieces of the main pole magnets.

4. 2. The rotating electric machine according to claim 1, The spoke magnet is divided into a plurality of magnet pieces in the radial direction of the rotor, A rotating electric machine characterized in that the radial length of the magnet pieces of the spoke magnets is shorter than the radial length of the magnet pieces of the main pole magnets.

5. 5. The rotating electric machine according to claim 4, The spoke magnets are divided in the radial direction of the rotor to include first magnet pieces and second magnet pieces having different radial lengths, A rotating electric machine characterized in that the radial length of the second magnet piece of the spoke magnet arranged on the side of the gap is shorter than the radial length of the first magnet piece arranged on the opposite side of the gap.

6. 5. The rotating electric machine according to claim 4, The spoke magnets are divided in the radial direction of the rotor to include first magnet pieces and second magnet pieces having different axial lengths, A rotating electric machine characterized in that the axial length of the second magnet piece of the spoke magnet arranged on the side of the gap is shorter than the axial length of the first magnet piece arranged on the opposite side of the gap.

7. 5. The rotating electric machine according to claim 4, The spoke magnets are divided in the radial direction of the rotor to include first magnet pieces and second magnet pieces having different circumferential lengths, A rotating electric machine characterized in that the circumferential length of the second magnet piece of the spoke magnet arranged on the side of the gap is shorter than the circumferential length of the first magnet piece arranged on the opposite side of the gap.

8. 2. The rotating electric machine according to claim 1, The rotor core has a main core located on the radial side of the gap relative to the main pole magnet, claw portions extending in a circumferential direction from a tip of the main core on the gap side, and a magnet holding plate arranged between the spoke magnets and the gap, The rotating electric machine is characterized in that the magnet holding plate is held by the claw portion.

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