Interior magnet rotor and interior magnet rotating machine

Abstract

An embedded magnet rotor (10) according to an embodiment of the present invention is equipped with: a rotor shaft extending in the rotation axis direction; a plurality of permanent magnets, at least one of which is provided to each magnetic pole; and a rotor core (100) which is attached to the radially outer side of the rotor shaft and in which a plurality of permanent-magnet storing holes (110) for storing the plurality of permanent magnets are formed. Each of the permanent magnets is disposed to be inclined relative to a virtual flat surface including the rotation axis. Each of the storing holes has an opening part (114) that is in communication with the radially outer side of the rotor core and that is sandwiched between an opening-part circumferentially inside chip (112) and an opening-part circumferentially outside chip (113) of the rotor core. The rotor core (100) has a relaxing part (120) formed in the opening part (114).

Description

[Technical field]

[0001] An embodiment of the present invention relates to an interior magnet rotor and an interior magnet rotating electric machine having the same. [Background technology]

[0002] Toward the realization of a low-carbon and decarbonized society, electric vehicles such as hybrid electric vehicles (HEVs) and electric vehicles (EVs) are becoming more widespread. Permanent magnet motors are generally used as the power source for these vehicles. Permanent magnet motors have excellent variable speed driving characteristics, so for example, a configuration in which two permanent magnets are arranged on each magnetic pole so that they face each other in the circumferential direction and open outward in the radial direction has been proposed and used. When two permanent magnets have the same specifications and are arranged symmetrically about the center (d-axis) of the magnetic pole, this is called a V-shaped arrangement.

[0003] In embedded magnet type rotors, there are cases where the permanent magnet storage holes of the rotor core, which house the permanent magnets and form a flux barrier, are not connected to the outside of the rotor core, that is, there is a top bridge, which is a bridge on the outer periphery, between the permanent magnet storage holes and the outer surface of the rotor core to mechanically support the centrifugal force acting on the core and permanent magnets on the outer diameter side.

[0004] However, if a top bridge is present, it acts as a magnetic path, generating leakage flux and causing a decrease in torque performance.

[0005] For this reason, a top bridgeless system is known in which a top bridge is not provided, and instead the permanent magnet storage hole of the rotor core is provided with an opening that communicates with the outside of the rotor core. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2020-014322 A Summary of the Invention [Problem to be solved by the invention]

[0007] In the top bridgeless system, an opening is provided on the outer surface of the rotor core, which causes a sudden change in magnetic resistance to the magnetic flux penetrating from the stator into the rotor between the parts with and without the core near the outer periphery of the rotor, i.e., between the opening and the part with the core, resulting in cogging torque and the associated noise.

[0008] An object of the present invention is to provide an interior magnet rotor and an interior magnet rotating electric machine that can reduce changes in magnetic reluctance and reduce cogging torque. [Means for solving the problem]

[0009] In order to achieve the above object, the embedded magnet rotor according to the embodiment of the present invention has a rotating shaft. Extend an embedded magnet type rotor comprising: a rotor shaft extending in a radial direction; a plurality of permanent magnets, at least one of which is provided on each magnetic pole; and a rotor core attached to the radial outside of the rotor shaft and having a plurality of permanent magnet storage holes formed therein for storing each of the plurality of permanent magnets, wherein each of the permanent magnet storage holes has an opening that communicates with the radial outside of the rotor core and is sandwiched between an opening circumferential inner tip and an opening circumferential outer tip of the rotor core, and a magnet holding outer protrusion is formed in the permanent magnet storage hole on the radial outside of the permanent magnet, and the rotor core has a mitigation portion formed in the shape of the opening circumferential inner tip and the opening circumferential outer tip so as to mitigate a sudden change in the circumferential direction of magnetic resistance against a magnetic flux penetrating from the radial outside of the rotor core into the rotor core, and the mitigation portion is ,before On the outer wall of the inner tip in the circumferential direction of the opening The radial thickness of the opening circumferential inner tip is continuously decreased as it approaches the opening. The inner tip outer surface inclined wall formed on the inner tip or the outer tip outer wall of the outer tip in the circumferential direction of the opening The radial thickness of the opening circumferential outer tip is continuously decreased as it approaches the opening. and an outer tip outer surface inclined wall formed thereon. [Brief description of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing a configuration of an embedded magnet type rotating electric machine according to a first embodiment. [Diagram 2] 2 is a partial cross-sectional view of a rotor core showing permanent magnet storage holes of the embedded magnet rotor according to the first embodiment. FIG. [Diagram 3] 4 is a partial cross-sectional view showing a relaxation portion of a permanent magnet housing hole of the embedded magnet rotor according to the first embodiment. FIG. [Figure 4] 5 is a graph showing a comparison of changes in magnetic flux density over time, illustrating the effect of the embedded magnet rotor according to the first embodiment. [Diagram 5] 5 is a graph showing a detailed comparison of time-dependent changes in magnetic flux density, illustrating the effect of the embedded magnet rotor according to the first embodiment. [Figure 6] 5 is a graph showing a comparison of changes in torque over time, illustrating the effect of the embedded magnet rotor according to the first embodiment. [Figure 7] 4 is a graph showing a comparison of torque magnitudes, illustrating the effect of the embedded magnet rotor according to the first embodiment. [Figure 8] 4 is a graph showing a comparison of the magnitude of the cogging torque harmonic components, which shows the effect of the interior permanent magnet rotor according to the first embodiment. [Figure 9] 4 is a graph showing a comparison of the magnitude of iron loss, illustrating the effect of the interior permanent magnet rotor according to the first embodiment. [Figure 10] FIG. 11 is a partial cross-sectional view showing a relaxation portion of a permanent magnet housing hole of an embedded magnet rotor according to a second embodiment. [Figure 11] FIG. 11 is a partial cross-sectional view showing a relaxation portion of a permanent magnet housing hole of an embedded magnet rotor according to a third embodiment. [Figure 12] FIG. 11 is a partial cross-sectional view showing a relaxation portion of a permanent magnet housing hole of an embedded magnet rotor according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an interior magnet rotor and an interior magnet 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 given the same reference numerals and duplicated explanations will be omitted.

[0012] [First embodiment] FIG. 1 is a cross-sectional view showing the configuration of an embedded magnet type rotating electric machine 1 according to a first embodiment.

[0013] The interior magnet type rotating electric machine 1 has an interior magnet type rotor 10 and a stator 20 .

[0014] The embedded magnet rotor 10 has a rotor shaft 11 extending in the direction of the rotation axis CL and rotatably supported by two bearings (not shown), a cylindrical rotor core 100 attached radially outside the rotor shaft 11, and a plurality of permanent magnets 12 arranged within the rotor core 100.

[0015] The stator 20 has a cylindrical stator core 21 arranged to surround the radial outside of the rotor core 100, and a stator winding (not shown) that passes through multiple stator slots 22 formed on the inner surface of the stator core 21 and is wound around the stator core 21.

[0016] For ease of explanation, the directions are defined below. The direction away from the rotation axis CL of the rotor shaft 11 is called the radial direction. The direction in which the embedded magnet rotor 10 rotates is called the circumferential direction. The direction parallel to the extension direction of the rotation axis CL is called the axial direction.

[0017] Two permanent magnets 12 are disposed on each magnetic pole, and are disposed at positions circumferentially symmetrical with respect to the central axis of the magnetic pole. The two permanent magnets 12 on each magnetic pole are disposed such that the circumferential spacing between them becomes wider as they move radially outward. In other words, the two permanent magnets 12 on each magnetic pole are disposed such that they open outward in the radial direction.

[0018] In the following, such a case will be described as an example, but the interior magnet type rotor 10 is not limited to having the magnet arrangement described above. That is, the number of permanent magnets 12 arranged in each magnetic pole is not limited to two. In addition, it is not limited to being symmetrical with respect to the central axis of the magnetic pole, and may be asymmetrical.

[0019] FIG. 2 is a partial cross-sectional view of the rotor core 100 showing the permanent magnet storage holes 110 of the interior magnet rotor 10 according to the first embodiment.

[0020] 2 shows one of two permanent magnet accommodating holes 110 arranged symmetrically with respect to the central axis (d-axis) of each magnetic pole of the rotor core 100. The permanent magnet accommodating hole 110 faces the other adjacent permanent magnet accommodating hole 110 via two center bridges 130 on the radially inner side.

[0021] A magnet holding outer protrusion 116 and a magnet holding inner protrusion 117 protrude from the permanent magnet storage hole 110, and the permanent magnet 12 (FIG. 1) is stored and held in the area sandwiched between them.

[0022] The radially outer side of the permanent magnet accommodating hole 110 communicates with the radially outer side of the rotor core outer circumferential surface 100a. That is, an opening 114 is formed in the radially outer portion of the permanent magnet accommodating hole 110.

[0023] In the region of one magnetic pole, the rotor core 100 is divided by two opposing permanent magnet storage holes 110 into a sector portion 100x that is sandwiched between the two permanent magnet storage holes 110 and extends radially outward from the two center bridges 130, and a magnetic pole outer portion 100y that is adjacent to the circumferential outside of the sector portion 100x.

[0024] The opening 114 is formed by two opposing walls: an opening circumferential inner tip 112 which is a protruding portion on the sector portion 100x side, and an opening circumferential outer tip 113 which is a protruding portion on the magnetic pole outer portion 100y side.

[0025] The opening circumferentially inner tip 112 is a radially outer portion across the recess 115 when viewed from the radially outer wall 111 of the through hole.

[0026] The opening circumferential outer tip 113 is a protruding portion on the radially outer side when viewed from the magnet holding outer protrusion 116 .

[0027] The mitigation portion 120 mitigates a sudden change in the circumferential direction of the magnetic resistance against the magnetic flux penetrating from the radial outside of the rotor core 100 into the inside of the rotor core 100. For this reason, the opening circumferential inner tip 112 and the opening circumferential outer tip 113 which form the opening 114 are formed in a shape that makes the circumferential change in the magnetic resistance gentle. Details of the mitigation portion 120 will be described later with reference to FIG. 3.

[0028] FIG. 3 is a partial cross-sectional view showing the relaxation portion 120 of the permanent magnet housing hole 110 of the embedded magnet rotor 10 according to the first embodiment.

[0029] The broken line indicates a conventional example, and is shown as a comparative example for explaining the contents and effects of the relaxation portion 120 of the permanent magnet storage hole 110 according to this embodiment. In the comparative example, the inner tip facing wall 112a of the opening circumferential inner tip 112, which is a protruding portion on the sector portion 100x side forming the opening 114, and the outer tip facing wall 113a of the opening circumferential outer tip 113, which is a protruding portion on the magnetic pole outer portion 100y side facing thereto, are included in the planes Sa and Sb extending in the axial direction. The planes Sa and Sb are parallel to each other, and a virtual plane Sc at the circumferential midpoint between them is a plane passing through the rotation axis CL of the rotor shaft 11.

[0030] On the other hand, an inner tip extension wall 121, which is an opposing surface at the opening circumferential inner tip 112 of the relaxation portion 120 according to this embodiment, is formed to be in the same plane as the through hole radially outer wall 111. Specifically, the inner tip extension wall 121 is formed to protrude radially outward toward the opening 114 further than the inner tip opposing wall 112a of the comparative example.

[0031] On the other hand, the outer tip opposing wall 122, which is the opposing surface at the opening circumferential outer tip 113, is formed so as to be parallel to the inner tip extension wall 121, which is the opposing surface at the opening circumferential inner tip 112. Specifically, in the comparative example, the circumferential width of the opening 114 in the comparative example, i.e., the distance between the inner tip opposing wall 112a and the outer tip opposing wall 113a, is formed to maintain a width w0. Therefore, the outer tip opposing wall 122 is formed so as to be recessed radially outward from the opening 114 compared to the outer tip opposing wall 113a in the comparative example.

[0032] Here, assuming that an imaginary plane Se passes through the center of the opening and is parallel to the inner tip extension wall 121 and the outer tip facing wall 122, the imaginary plane Se is inclined at an angle Θ with respect to the imaginary plane Sc.

[0033] Thus, in the comparative example, the inner tip opposing wall 112a and the outer tip opposing wall 113a are both formed approximately along the radial direction, so when viewed from the radially outer stator 20 in the direction of the rotation axis CL, the width of the opening 114 is w0, and the opening 114 is formed so that it can be seen through to this width w0 along the radial direction.

[0034] On the other hand, in the relaxation portion 120 according to the present embodiment, due to the formation of the inner tip extension wall 121 and the outer tip opposing wall 122, the width of the opening 114 when seen from the radially outer stator 20, looking through the opening 114 in the direction of the rotation axis CL along the radial direction, is reduced to w1 (=w0·cosΘ). Also, the thicknesses of the opening circumferentially inner tip 112 and the opening circumferentially outer tip 113 on both sides of the width w1 through which the opening 114 can be seen along the radial direction as seen from the radially outer stator 20, continuously decrease as they approach the opening 114.

[0035] Next, the operation and effects of the interior magnet rotor 10 according to the present embodiment described above will be described.

[0036] Fig. 4 is a graph showing a comparison of time-dependent changes in magnetic flux density, which indicates the effect of the embedded magnet rotor 10 according to the first embodiment. Fig. 5 is a graph showing a detailed comparison of time-dependent changes in magnetic flux density, which indicates the effect of the embedded magnet rotor 10 according to the first embodiment. The horizontal axis of Fig. 4 and Fig. 5 is angle (electrical angle), and the vertical axis is magnetic flux density [T]. The dashed line indicates a comparative example, and the solid line indicates the case of this embodiment.

[0037] For example, the changes in part C in Fig. 4 before and after the magnetic flux density increases and reaches its maximum value will be compared in more detail with Fig. 5. As shown in Fig. 5, the change in part A in the present embodiment is gentler than the change in part B in the comparative example.

[0038] 6 is a graph showing a comparison of changes in torque over time, illustrating the effect of the interior magnet rotor 10 according to the first embodiment. The horizontal axis is time, and the vertical axis is torque (pu).

[0039] The dashed line indicates the comparative example, and the solid line indicates the present embodiment. As shown in Fig. 6, the comparative example shows a larger change in each cycle than the present embodiment.

[0040] 7 is a graph showing a comparison of torque magnitudes, illustrating the effect of the embedded magnet rotor 10 according to the first embodiment. The horizontal axis represents the cases, that is, the comparative example and this embodiment. The vertical axis represents the relative value of the time average of torque. The torque value in this embodiment is lower than the torque value in the comparative example, but the reduction is less than about 0.3%.

[0041] 8 is a graph showing a comparison of the magnitude of the cogging torque harmonic components, which shows the effect of the interior permanent magnet rotor 10 according to the first embodiment. The horizontal axis shows the cases where the 12th and 24th harmonics appear significantly as cogging torque harmonic components. The vertical axis shows the relative value of the torque amplitude.

[0042] As shown in FIG. 8, in the case of this embodiment, the cogging torque harmonic components increase by about 4% for the 12th harmonic, but decrease by about 80% for the 24th harmonic, compared to the comparative example. Overall, a harmonic suppression effect is obtained.

[0043] 9 is a graph showing a comparison of the magnitude of iron loss, which shows the effect of the embedded magnet rotor 10 according to the first embodiment. The horizontal axis shows the cases, that is, the comparative example and this embodiment, and the vertical axis shows the relative value of iron loss.

[0044] As shown in FIG. 9, the iron loss in this embodiment is reduced by about 3% compared to the comparative example.

[0045] As described above, in the mitigation section 120 of this embodiment, by providing the inner tip extension wall 121 and the outer tip opposing wall 122, the width of the opening 114 as seen from the radially outer stator 20 is reduced. Also, the thicknesses of the opening circumferentially inner tip 112 and the opening circumferentially outer tip 113 on both sides of the width w1 through which the opening 114 can be seen in the radial direction are continuously reduced as they approach the opening. As a result, a sudden change in the circumferential direction of the magnetic reluctance against the magnetic flux penetrating from the radial outside of the rotor core 100 into the rotor core 100 is mitigated.

[0046] As a result, the cogging torque caused by the presence of the openings 114 formed in the rotor core 100 is suppressed, and the iron loss is also reduced, leading to improved efficiency.

[0047] [Second embodiment] 10 is a partial cross-sectional view showing the relaxation portion 120a of the permanent magnet storage hole 110 of the embedded magnet rotor 10 according to the second embodiment. This embodiment is a modification of the first embodiment, and only the shape of the relaxation portion 120a is different.

[0048] In the relaxation portion 120a of this embodiment, the inner tip opposing wall 112a of the opening circumferentially inner tip 112 is similar to that of the comparative example. On the other hand, an outer tip inner surface inclined wall 123 is formed on the outer tip inner wall 113b of the opening circumferentially outer tip 113, and the radial thickness of the opening circumferentially outer tip 113 continuously decreases toward the opening 114. Note that an inner tip inner surface inclined wall may be provided on the inner tip inner wall of the opening circumferentially inner tip 112.

[0049] In this manner, in this embodiment, by simply cutting out a portion of the opening circumferential outer tip 113 in the comparative example, the sudden change in the circumferential magnetic resistance against the magnetic flux penetrating from the radial outside of the rotor core 100 into the interior of the rotor core 100 is mitigated.

[0050] [Third embodiment] 11 is a partial cross-sectional view showing the relaxation portion 120b of the permanent magnet storage hole 110 of the embedded magnet rotor 10 according to the third embodiment. This embodiment is a modification of the first embodiment, and only the shape of the relaxation portion 120b is different.

[0051] In the relaxation portion 120b of this embodiment, an inner tip outer surface inclined wall 124 is formed on the inner tip outer wall 112c of the opening circumferential inner tip 112. Also, an outer tip outer surface inclined wall 125 is formed on the outer tip outer wall 113c of the opening circumferential outer tip 113. As a result, the radial thicknesses of the opening circumferential inner tip 112 and the opening circumferential outer tip 113 continuously decrease as they approach the opening 114. Note that either the inner tip outer surface inclined wall 124 or the outer tip outer surface inclined wall 125 may be formed.

[0052] In this manner, in the present embodiment, by simply cutting out a portion of the opening circumferential inner tip 112 and the opening circumferential outer tip 113 in the comparative example, the sudden change in the circumferential magnetic resistance against the magnetic flux penetrating from the radial outside of the rotor core 100 into the interior of the rotor core 100 is mitigated.

[0053] [Fourth embodiment] 12 is a partial cross-sectional view showing the relaxation portion 120c of the permanent magnet storage hole 110 of the embedded magnet rotor 10 according to the fourth embodiment. This embodiment is a combination of the second and third embodiments, and only the shape of the relaxation portion 120c is different.

[0054] In the relaxation portion 120c of this embodiment, an inner tip outer surface inclined wall 124 is formed on the inner tip outer wall 112c of the opening circumferentially inner tip 112. Also, an outer tip inner surface inclined wall 123 is formed on the outer tip inner wall 113b of the opening circumferentially outer tip 113, and an outer tip outer surface inclined wall 125 is formed on the outer tip outer wall 113c. As a result, the radial thicknesses of the opening circumferentially inner tip 112 and the opening circumferentially outer tip 113 continuously decrease as they approach the opening 114.

[0055] In this manner, in the present embodiment, by simply cutting out a portion of the opening circumferential inner tip 112 and the opening circumferential outer tip 113 in the comparative example, the sudden change in the circumferential magnetic resistance against the magnetic flux penetrating from the radial outside of the rotor core 100 into the interior of the rotor core 100 is mitigated.

[0056] According to the embodiments described above, it is possible to provide an interior permanent magnet rotor and an interior permanent magnet rotating electric machine that can reduce the change in magnetic reluctance and reduce cogging torque.

[0057] [Other embodiments] Although the embodiments of the present invention have been described above, the embodiments are presented as examples and are not intended to limit the scope of the invention. In addition, the features of each embodiment may be combined. Furthermore, the embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. The embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and gist of the invention. [Explanation of symbols]

[0058] 1... permanent magnet rotating electric machine, 10... permanent magnet rotor, 11... rotor shaft, 12... permanent magnet, 20... stator, 21... stator core, 22... stator slot, 100... rotor core, 100a... rotor core outer surface, 100x... sector-shaped portion, 100y... magnetic pole outer portion, 110... permanent magnet storage hole, 111... through hole radial outer wall, 112... opening circumferential inner tip, 112a... inner tip facing wall, 112b... inner tip inner wall, 112c... inner tip outer wall, 113... opening circumferential Direction outer tip, 113a...outer tip facing wall, 113b...outer tip inner wall, 113c...outer tip outer wall, 114...opening, 115...recess, 116...magnet holding outer protrusion, 117...magnet holding inner protrusion, 120, 120a, 120b, 120c...relaxation portion, 121...inner tip extension wall, 122...outer tip facing wall, 123...outer tip inner surface inclined wall, 124...inner tip outer surface inclined wall, 125...outer tip outer surface inclined wall, 130...center bridge, CL...rotation axis

Claims

1. A rotor shaft extending in the direction in which the rotation axis extends; A plurality of permanent magnets, at least one for each magnetic pole; a rotor core attached to the radially outer side of the rotor shaft and having a plurality of permanent magnet housing holes formed therein for housing each of the plurality of permanent magnets; An interior magnet rotor comprising: Each of the permanent magnet storage holes has an opening that communicates with the radial outside of the rotor core and is sandwiched between an opening circumferential inner tip and an opening circumferential outer tip of the rotor core, The permanent magnet storage hole is provided with a magnet holding outer protrusion on the radially outer side of the permanent magnet, the rotor core has a mitigation portion in which the shapes of the opening circumferential inner tip and the opening circumferential outer tip are formed so as to mitigate a sudden change in magnetic resistance in a circumferential direction against a magnetic flux penetrating from a radial outside of the rotor core into the rotor core, the mitigation portion has an inner tip outer surface inclined wall formed on an inner tip outer wall such that a radial thickness of the opening circumferential direction inner tip continuously decreases as the opening circumferential direction inner tip approaches the opening, or an outer tip outer surface inclined wall formed on an outer tip outer wall such that a radial thickness of the opening circumferential direction outer tip continuously decreases as the opening circumferential direction outer tip approaches the opening, An embedded magnet rotor characterized by:

2. 2. The embedded magnet rotor according to claim 1, wherein a first surface of the opening circumferential inner tip facing the opening and a second surface of the opening circumferential outer tip facing the opening are formed parallel to each other.

3. the relaxation portion has an inner tip extension wall where an inner tip in the circumferential direction of the opening faces the opening, and an outer tip opposing wall where an outer tip in the circumferential direction of the opening faces the opening, An imaginary plane located at the center between the inner tip extension wall and the outer tip facing wall is formed to have an angle with respect to an imaginary plane including the center of the opening and the rotation axis.

2. The embedded magnet rotor according to claim 1 .

4. 2. The embedded magnet rotor according to claim 1, wherein the plurality of permanent magnets include two permanent magnets arranged in each of the magnetic poles so as to be aligned in the circumferential direction and to face each other.

5. An embedded magnet rotor according to any one of claims 1 to 4, a cylindrical stator core disposed so as to surround the outer periphery of the rotor core in the radial direction; and a stator having a stator winding wound around the stator core and passing through a plurality of stator slots formed on an inner peripheral surface of the stator core; Two bearings supporting the rotor shaft; An embedded magnet type rotating electric machine comprising:

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