JP7173480B2 - Permanent magnet rotors and rotating electrical machines - Google Patents

Description

The present invention relates to permanent magnet rotors and rotating electrical machines, and more particularly to permanent magnet rotors with permanent magnets embedded in the rotor core and rotating electrical machines having such permanent magnet rotors.

2. Description of the Related Art Permanent magnet rotors used in rotary electric machines such as embedded permanent magnet (IPM) motors are required to improve output torque and reduce torque ripple and cogging torque. Therefore, attempts have been made to improve the arrangement and shape of the slots for embedding the permanent magnets in the rotor core.

For example, in Patent Document 1, the sizes of slit portions (slots) of multiple layers and the residual magnetic flux density of permanent magnets embedded in the slit portions of each layer are defined so as to satisfy a predetermined relationship, and the slit portions A part thereof is formed with an empty slit portion in which no permanent magnet is embedded. Due to these configurations, the magnetic flux density distribution formed in the gap between the stator and the stator when it is installed in the rotating electrical machine becomes a stepped distribution shape close to a sine wave, which is effective in reducing torque ripple and cogging torque. It is said to have

JP-A-2002-78259

In a permanent magnet rotor, empty slits in which permanent magnets are not embedded are also called flux barriers, and increase magnetic resistance in the magnetic flux path along the d-axis from the inner circumference side to the outer circumference side of the rotor core through the center of the magnet. This works to improve the reluctance torque of the permanent magnet rotor. As shown in FIG. 7, in conventional general permanent magnet rotors 100 including the one disclosed in Patent Document 1, the flux barrier 117 is similar to the slits 113, 114, 115 in which the permanent magnets 116 are embedded. , is formed in an arcuate shape that protrudes toward the radially central portion of the rotor core 111 . In Patent Document 1, the length L (dimension along the circumferential direction of the arc) of the flux barrier 117 is set in each layer from the viewpoint of converting the magnetic flux density formed in the gap between the stator into a sine wave. However, regarding the shape and dimensions of the flux barrier 117, other than arc-shaped slits 113, 114, 115 in which the permanent magnets 116 are embedded are considered. do not have.

However, by devising the shape of the flux barrier 117, it may be possible to further improve the reluctance torque in the rotating electrical machine in which the permanent magnet rotor 100 is incorporated. Improving the reluctance torque can improve the output torque of the rotary electric machine.

The problem to be solved by the present invention is to provide a permanent magnet rotor capable of giving a large reluctance torque and a rotary electric machine having such a permanent magnet rotor by examining the shape of the flux barrier.

In order to solve the above-described problems, a permanent magnet rotor according to the present invention is a permanent magnet rotor having a rotor core and permanent magnets embedded in the rotor core and forming magnetic poles. A plurality of embedded slots are provided in the circumferential direction of the rotor core, and flux barriers are provided between the plurality of slots as gaps in which the permanent magnets are not embedded, and the flux barriers are provided inside the rotor core. The distance between the edge on the peripheral side and the edge on the outer peripheral side has a portion larger than the distance of the slot.

Here, between the slots and the flux barriers adjacent to each other, a bridge connecting an outer peripheral portion and an inner peripheral portion of the rotor core is formed integrally with the rotor core. In a cross section perpendicular to the axis of rotation, the bridge has a constricted portion with the smallest dimension in the width direction along the adjacent direction of the slot and the flux barrier, and crosses the constricted portion in the width direction. Along the direction, the widthwise dimension gradually widens, and the edges of the slot and the flux barrier on both sides of the narrowed portion in the widthwise direction are linear or extend the width of the bridge. It is preferable that it has a curved shape that is convex toward the inside of the direction.

In this case, the slot outer corner, which is the corner on the outer peripheral side of the slot facing the bridge, has an R shape, and the tangent along the direction of the centrifugal force circumscribing the R shape of the slot outer corner is , an inner corner of the barrier that passes through the bridge and intersects the edge of the flux barrier may have an R shape.

The radius of curvature of the R shape of the inner corner of the barrier is preferably larger than the radius of curvature of the R shape of the outer corner of the slot.

In addition, an R shape is also formed in the inner corner of the slot, which is the corner on the inner peripheral side of the slot, and the outer barrier corner, which is the corner on the outer peripheral side of the flux barrier, which are opposed to each other with the bridge interposed therebetween. Preferably, the radius of curvature of the R shape is larger at the inner barrier corner and the outer slot corner than at the inner slot corner and the outer barrier corner.

In the flux barrier, it is preferable that a bridge connecting an outer peripheral portion and an inner peripheral portion of the flux barrier is formed integrally with the rotor core at a circumferentially intermediate portion of the rotor core.

A rotary electric machine according to the present invention has a permanent magnet rotor as described above.

In the permanent magnet rotor according to the above-described invention, the flux barrier has a portion in which the distance (radial dimension) between the inner peripheral edge and the outer peripheral edge of the rotor core is larger than the radial dimension of the slots. is provided. At a position where the radial dimension of the flux barrier is long, the magnetic resistance of the d-axis magnetic flux path increases. As a result, a large reluctance torque is obtained compared to the case of using a simple arc-shaped flux barrier in which the radial dimension of the flux barrier is the same as the radial dimension of the slot, as disclosed in US Pat. It becomes a permanent magnet rotor that gives

Here, between the slots and flux barriers adjacent to each other, a bridge connecting the outer peripheral side portion and the inner peripheral side portion of the rotor core is formed integrally with the rotor core. in which the bridge has a constriction with the smallest widthwise dimension along the adjacent direction of the slot and the flux barrier, and from the constriction on both sides along the direction intersecting the widthwise direction, the widthwise dimension has a shape that gradually expands, and on both sides of the constricted portion in the width direction, the edges of the slot and the flux barrier take a straight shape or a curved shape that is convex toward the inside in the width direction of the bridge. , the presence of narrowed portions in the bridge can reduce leakage of effective magnetic flux such as permanent magnet magnetic flux, d-axis magnetic flux, and q-axis magnetic flux. As a result, the magnet torque and reluctance torque generated in the motor are improved, and by suppressing torque reduction due to leakage of effective magnetic flux, a permanent magnet rotor capable of achieving both high output and stable high-speed rotation can be obtained. In addition, on both sides of the constricted portion in the width direction, the edges of the slots and the flux barriers are linear or convex inward in the width direction of the bridge, so that the permanent magnet rotor rotates. In this case, it is possible to alleviate the concentration of bending stress on both sides of the constricted portion in the width direction. As a result, even if the narrowed portion is provided in the bridge, sufficient mechanical strength to withstand high-speed rotation can be secured in the bridge.

In this case, the slot outer corner, which is the corner on the outer peripheral side of the slot facing the bridge, has an R shape, and the tangent line along the direction of the centrifugal force circumscribing the R shape of the slot outer corner faces the bridge. According to the configuration in which the barrier inner corner, which passes through and intersects the edge of the flux barrier, has an R shape, when the permanent magnet rotor rotates, the slot outer corner located diagonally of the bridge And the concentration of bending stress on the inner corner of the barrier can be mitigated by the presence of the R shape. As a result, even if the width of the bridge is narrowed, it becomes easier to ensure sufficient mechanical strength to withstand high-speed rotation.

According to the configuration in which the radius of curvature of the R shape of the inner corner of the barrier is larger than the radius of curvature of the R shape of the outer corner of the slot, it becomes easier to form a narrow region in the bridge. As a result, effective magnetic flux leakage in the bridge can be effectively reduced.

In addition, an R shape is also formed in the slot inner corner, which is the inner peripheral corner of the slot, and the barrier outer corner, which is the outer peripheral corner of the flux barrier, which face each other with the bridge interposed therebetween. When the radius of curvature of the R shape is larger at the inner barrier corner and the outer slot corner than at the inner slot corner and the outer barrier corner, it is easy to form a long narrow region in the bridge. As a result, magnetic flux leakage in the bridge can be effectively reduced.

In the flux barrier, when a bridge connecting the outer peripheral side portion and the inner peripheral side portion of the flux barrier is formed integrally with the rotor core in the middle of the rotor core in the circumferential direction, the permanent magnet rotor is formed. The centrifugal force generated during rotation is not concentrated on the bridge provided between the slot and the flux barrier, but is distributed as tensile stress to the bridge provided in the middle of the flux barrier. As a result, it becomes easier to cope with high-speed rotation of the permanent magnet rotor while narrowing the width of each bridge.

A rotary electric machine according to the present invention has the above-described permanent magnet rotor, and the flux barrier provided in the permanent magnet rotor is provided with a portion having a larger radial dimension. , generates a large reluctance torque.

1 is a cross-sectional view showing the configuration of a permanent magnet rotor and a rotary electric machine according to a first embodiment of the present invention; FIG. FIG. 2 is an enlarged view of a part of the cross-sectional view of FIG. 1; 3 is a further enlarged view of the vicinity of the flux barrier in FIG. 2; FIG. FIG. 4 is a cross-sectional view showing the configuration of a permanent magnet rotor according to a modification of the first embodiment; FIG. 8 is a diagram showing the vicinity of a flux barrier in a permanent magnet rotor according to a second embodiment of the present invention; FIG. 10 is a diagram showing the vicinity of a flux barrier in a permanent magnet rotor according to a third embodiment of the present invention; FIG. 3 is a cross-sectional view showing the configuration of a conventional general permanent magnet rotor; (a) is an overall view, and (b) is an enlarged view near the flux barrier. FIG. 5 is a diagram showing the distribution of principal stresses applied to a conventional general permanent magnet rotor (conventional form A); (a) shows an overall image, and (b) shows an enlarged image near the flux barrier. FIG. 10 is a diagram showing the distribution of principal stresses applied to a general conventional permanent magnet rotor in which the width of bridges is widened (conventional form B). (a) shows an overall image, and (b) shows an enlarged image near the flux barrier. FIG. 5 is a diagram showing distribution of principal stress applied to a permanent magnet rotor (Embodiment A) according to a second embodiment of the present invention; (a) shows the overall image, and (b) and (c) show enlarged images near the flux barrier. FIG. 10 is a diagram showing distribution of principal stress applied to a permanent magnet rotor (Embodiment B) according to a third embodiment of the present invention; (a) shows an overall image, and (b) shows an enlarged image near the flux barrier. FIG. 2 is a diagram showing the output characteristics of a conventional motor having a general permanent magnet rotor. B). FIG. 7 is a diagram showing output characteristics of a motor including a permanent magnet rotor (Embodiment A) according to a second embodiment of the present invention; (a) speed-torque characteristics and (b) FIG. 5 is a diagram showing a comparison of speed-output characteristics; It is a figure which compares the winding magnetic flux linkage number of permanent-magnet magnetic flux.

A permanent magnet rotor and a rotary electric machine according to embodiments of the present invention will be described in detail below with reference to the drawings.

[1] First Embodiment First, a permanent magnet rotor and a rotating electric machine according to a first embodiment of the present invention will be described in detail.

[Configuration of Rotating Electric Machine]
A schematic of a rotating electric machine according to a first embodiment of the present invention is shown in FIG. The rotary electric machine 1 has a permanent magnet rotor 10 according to the first embodiment of the invention. In this specification, the case where the rotary electric machine 1 is a motor will be mainly described, but a similar configuration can be applied to a case where it is a generator.

The rotating electrical machine 1 is configured as an embedded permanent magnet (IPM) motor. The motor 1 has a hollow cylindrical stator (stator) 30 and a rotor (permanent magnet rotor) 10 coaxially supported in a hollow portion of the stator 30 so as to be axially rotatable.

The stator 30 has a stator core 31 and coils (not shown). The stator core 31 is formed by laminating a plurality of layers of electromagnetic steel sheets, and is integrally provided with an annular back yoke portion 31a and a plurality of teeth 31b projecting inwardly from the annular back yoke portion 31a. ing. A coil is wound around the outer periphery of each tooth 31b.

The rotor 10 has a rotor core 11 having a substantially cylindrical outer shape and a plurality of permanent magnets 16 embedded in the rotor core 11 . A hollow portion 12 through which the drive shaft 40 can be inserted penetrates through the center of the rotor core 11 . A gap is ensured between the teeth 31 b of the stator core 31 and the outer peripheral surface of the rotor core 11 in a state in which the rotor 10 is coaxially accommodated in the hollow portion 12 of the stator 30 . Details of the configuration of the rotor 10 are described below.

[Configuration of Permanent Magnet Rotor]
As described above, the rotor (permanent magnet rotor) 10 has the rotor core 11 and the permanent magnets 16 . The configuration of the rotor 10 is shown in FIGS. 1-3. FIG. 2 shows one magnetic pole of the rotor 10. A plurality of (here, eight) magnetic poles are continuously arranged rotationally symmetrically while the polarities of the permanent magnets 16 are alternately changed. The overall structure of the rotor 10 is as shown in FIG. It should be noted that hereinafter, terms indicating directions in the rotating body such as “circumferential direction”, “inner circumference”, “outer circumference”, and “radial direction” refer to directions with respect to the rotor core 11 unless otherwise specified.

The rotor core 11 is configured by laminating a plurality of layers of electromagnetic steel sheets, and has a substantially cylindrical outer shape. Slots 13 , 14 , 15 and a flux barrier 17 are formed in the rotor core 11 as gaps extending through or recessed in the axial direction. Permanent magnets 16 can be embedded in the slots 13 , 14 , 15 . The flux barrier 17 does not have the permanent magnets 16 embedded therein and is maintained as an air gap. Alternatively, the flux barrier 17 may be filled with a non-magnetic material.

Slots 13 , 14 , 15 have a convex shape toward the center of rotation of rotor core 11 . The specific shape of the slots 13, 14, 15 is not particularly limited, but here each has a substantially arc shape. In other words, the inner peripheral edge (13b, etc.) located on the inner peripheral side of the rotor core 11 and the outer peripheral edge (13a, etc.) located on the outer peripheral side of the rotor core 11 each protrude toward the inside of the rotor core 11. is formed as a circular arc. A radial edge (13c, etc.) connects the inner peripheral edge (13b, etc.) and the outer peripheral edge (13a, etc.).

Although the number of layers of the slots 13, 14, 15 is not particularly limited, in the present embodiment, from the viewpoint of improving reluctance torque, etc., the slots 13, 14, 15 in which the permanent magnets 16 can be embedded are provided in multiple layers. there is That is, along the radial direction of the rotor core 11, a plurality of layers (here, three layers) of slots 13, 14, and 15 are spaced apart from each other. A permanent magnet 16 of the same polarity is embedded in each slot 13 , 14 , 15 . A metal magnet is preferably used as the permanent magnet 16 . In this embodiment, the permanent magnets 16 are embedded in all the slots 13, 14, and 15 of the three layers, but for the purpose of reducing the mass of the permanent magnet rotor 10, some of the slots, for example, the maximum A configuration in which the permanent magnets 16 are not embedded in the slots 15 of the outer layer may be employed.

The slots 13 , 14 , 15 forming the innermost layer, the intermediate layer, and the outermost layer are each divided into two in the circumferential direction of the rotor core 11 . In the intermediate layer and the outermost layer, slots 14 and 15 divided into two are adjacent to each other in the circumferential direction of rotor core 11 via bridge 18 . On the other hand, in the innermost layer, a flux barrier 17 is formed between the slots 13 divided into two adjacent in the circumferential direction of the rotor core 11 . In this embodiment, each component of the rotor 10 including the slots 13, 14, 15 of each layer and the flux barrier 17 is aligned with the rotor d-axis (indicated by d' in the drawing) along the radial direction of the rotor core 11. are formed symmetrically with respect to

In rotor core 11, bridges 18, 19, and 20 connecting inner and outer peripheral portions of slots 13, 14, and 15 and flux barriers 17 are integrally formed with rotor core 11. . Each of the bridges 18, 19, and 20 separates the outer peripheral portion of the rotor core 11 from the inner peripheral portion by the action of centrifugal force when the rotor 10 is axially rotated. It plays a role of preventing scattering of the permanent magnet 16 embedded in.

In this embodiment, due to the effect of the shape of the flux barrier 17 and the shape of the bridge 20 formed between the innermost slot 13 and the flux barrier 17, high output of the rotor 10 and stable rotation at high speed are achieved. do. These shapes will be described in detail below mainly with reference to FIG.

(1) Radial Length of Flux Barrier In the present embodiment, the radial length between the flux barrier 17 and the slot 13 adjacent to the flux barrier 17 (here, the innermost slot) has a predetermined relationship. is making Here, the radial lengths of the flux barriers 17 and the slots 13 are the lengths in the direction intersecting the circumferential direction of the rotor core 11, that is, the inner peripheral side edges 17b/13b and the outer peripheral side edges 17a/13a. refers to the distance between

The slot 13 is formed in a substantially arcuate shape, and the radial length lm is substantially uniform along the longitudinal direction of the arcuate shape. On the other hand, the radial length Lm of the flux barrier 17 is approximately equal to the radial length lm of the slot 13 at a position near the radial edge 17c facing the slot 13 (a position away from the rotor d-axis). Although they are equal, they are larger than the radial length lm of the slots 13 at positions distant from the slots 13 (positions approaching the rotor d-axis).

In the flux barrier 17, the outer peripheral edge 17a has a substantially circular arc shape that protrudes toward the inner peripheral side of the rotor core 11, and corresponds to the extrapolation of the outer peripheral edge 13a of the adjacent slot 13. It has shape and position. However, the inner peripheral side edge 17b of the flux barrier 17 increases along the circumferential direction (toward the rotor d-axis side) from the position of the radial direction edge 17c facing the slot 13, and the outer peripheral side edge It extends toward the inner peripheral side of the rotor core 11 away from 17a. As a result, the radial length Lm of the flux barrier 17 is larger than the radial length lm of the slot 13 at a position distant from the slot 13 (at a position toward the d-axis side of the rotor).

By providing the flux barrier 17 in the rotor core 11 , the magnetic resistance of the d-axis magnetic flux path increases in the rotor 10 . Then, the difference in magnetic resistance with the q-axis magnetic flux path increases, and the reluctance torque of the motor 1 can be improved. The greater the dimension of the flux barrier 17 along the d-axis flux path, the greater this effect. Therefore, as described above, by providing the flux barrier 17 with a portion where the radial length Lm is larger than the radial length lm of the slot 13, the conventional general rotor 100 shown in FIG. In addition, more reluctance torque can be induced in rotor 10 than if flux barriers 117 had the same uniform radial length as slots 113 .

The effect of improving the reluctance torque increases as the radial length Lm of the flux barrier 17 increases. From the viewpoint of sufficiently improving the reluctance torque, the maximum value of the radial length Lm of the flux barrier 17 is preferably 1.5 times or more the radial length lm of the slot 13 . On the other hand, if the radial length Lm of the flux barrier 17 is too large, the effect of improving the reluctance torque will be saturated and the mechanical strength of the rotor core 11 may decrease. It is preferable to suppress the length to 5.0 times or less of the radial length lm.

As described above, by providing the flux barrier 17 with a portion having a large radial length Lm, the effect of improving the reluctance torque generated in the rotor 10 can be obtained. Regarding the position, from the viewpoint of preventing the mechanical strength of the bridge 20 from being lowered, it is better to keep the radial length Lm approximately equal to the radial length lm of the slot 13 .

The layer on which the flux barrier 17 is provided is not particularly limited, but by providing the flux barrier 17 adjacent to the innermost slot 13 as in this embodiment, the reluctance torque generated in the rotor 10 can be effectively reduced. can be improved, and it is easier to achieve a sinusoidal magnetic flux density waveform in the air gap between the rotor 10 and the stator 30 . Further, it is easy to form a portion having a large radial length Lm in the flux barrier 17 while avoiding interference with the slots 14, 15, etc. of other layers. However, if necessary, the above-described flux barrier 17 having a portion with an increased radial length Lm may also be provided at a position between the slots 14 and 15 other than the innermost layer. . Furthermore, although the specific shape of the flux barrier 17 is not particularly limited, the inner peripheral side edge 17b of the flux barrier 17 is not the outer peripheral side edge 17a as in the present embodiment, but the other If the configuration is such that the radial length Lm is widened by moving away from the edge, the radial length can be increased by utilizing the surface of the rotor core 11 on the inner peripheral side of the innermost layer slot 13 where no slots are formed. It is easy to ensure a large length Lm.

(2) Bridge Shape As described above, the rotor core 11 has bridges 18, 19, and 20 that connect the slots 13, 14, and 15 and the flux barrier 17 between the inner and outer peripheral portions thereof. formed. Of these, the bridge 20 provided between the slot 13 in the innermost layer and the flux barrier 17 is focused. The shape of the bridge 20 is defined by the shapes of the edges of the slot 13 and the flux barrier 17 facing each other with the bridge 20 interposed therebetween.

In the slot 13, of the two corners 13d and 13e facing the bridge 20, the slot outer corner 13e located on the outer peripheral side of the rotor core 11 has an R shape. That is, in the cross section of the rotor 10, the slot outer corner 13e passes inside the slot 13 from the extrapolated line of the outer peripheral side edge 13a of the slot 13 and the extrapolated line of the radial edge 13c. It is configured as an outwardly convex curve and smoothly joined to the outer peripheral side edge 13a and the radial direction edge 13c.

On the other hand, in the flux barrier 17, of the two corners 17d and 17e facing the bridge 20, the inner barrier corner 17d located on the inner peripheral side of the rotor core 11 has an R shape. That is, in the cross section of the rotor 10, the barrier inner corner 17d passes inside the flux barrier 17 from the extrapolation line of the inner peripheral edge 17b and the extrapolation line of the radial edge 17c of the flux barrier 17. The flux barrier 17 is configured as an outwardly convex curved line, and is smoothly joined to the inner peripheral side edge 17b and the radial direction edge 17c. In the illustrated embodiment, the R-shaped curvature radius of the barrier inner corner 17d is large, and the radial length Lm of the flux barrier 17 is also large. Although the distinction between the two is not necessarily clear, such a form in which the inner peripheral side edge 17b is connected to the radial direction edge 17c in a smooth R shape is also included. A curved portion including a position where a diagonal line b defined as a tangent line along the direction of centrifugal force circumscribing the R shape of the slot outer corner 13e passes through the bridge 20 and intersects the edge of the flux barrier 17 is defined as the barrier. The inner corner portion 17d is used as long as the barrier inner corner portion 17d has an R shape.

In this embodiment, comparing the rounded shapes of the slot outer corner 13e and the barrier inner corner 17d, the curvature radius of the barrier inner corner 17d is larger than the curvature radius of the slot outer corner 13e. In other words, the barrier inner corner 17d has a rounded shape that is more gently curved than the slot outer corner 13e.

Corners other than the slot outer corner 13e facing the bridge 20 and the barrier inner corner 17d, that is, the slot inner corner 13d positioned on the inner peripheral side of the slot 13 and the barrier outer corner 13d positioned on the outer peripheral side of the flux barrier 17 The corner portion 17e may have an R shape or may not have an R shape and may be formed in an angular shape. In the illustrated form, the slot inner corner 13d and the barrier outer corner 17e also have an R shape, but the curvature radii of the slot outer corner 13e and the barrier inner corner 17d are larger than their curvature radii. The slot inner corner 13d and the barrier outer corner 17e have a shape closer to a square. In the illustrated form, the relationship of the radii of curvature is as follows.
(barrier inner corner 17d)>(slot outer corner 13e)>(barrier outer corner 17e)≈(slot inner corner 13d)

In the rotor 10 according to this embodiment, at the edges of the slots 13 and the flux barriers 17 that define the shape of the bridges 20, the barrier inner corners 17d and the slot outer corners 13e, as well as the barrier outer corners, are formed as described above. Since the portion 17e and the slot inner corner portion 13d are rounded, the width w of the bridge 20, that is, the dimension of the bridge 20 in the direction along which the slot 13 and the flux barrier 17 are adjacent to each other, is equal to the longitudinal direction a. It changes along (a direction that intersects the width direction and connects the inner peripheral side and the outer peripheral side of the bridge 20). That is, the bridge 20 has a constricted portion 20a having the narrowest width w in the middle portion along the longitudinal direction a. The constriction 20a occupies a part of the length of the bridge 20 along the longitudinal direction a. , the width w of the bridge 20 gradually widens.

Thus, by providing the bridge 20 with the narrowed portion 20a having a narrowed width w, effective magnetic flux leakage in the bridge 20, that is, the magnetic flux of the permanent magnet 16, the d-axis magnetic flux, and the q-axis magnetic flux It is possible to suppress the short circuit in the rotor core 11 of the magnetic flux from the coil corresponding to . By reducing the leakage of the effective magnetic flux in the bridge 20, the magnet torque and the reluctance torque of the motor 1 in which the rotor 10 is installed can be increased. As a result, the motor 1 can achieve both stable high-speed rotation and high output.

In the bridge 20, if there is a constricted portion 20a with a narrow width w along the longitudinal direction a, the amount of magnetic flux passing through the bridge 20 is defined by the width w of the constricted portion 20a. Even if the bridge 20 has a portion with the widest width w, magnetic flux leakage in the entire bridge 20 can be suppressed. In particular, the width of the bridge w is sharply reduced from both sides in the longitudinal direction a toward the constricted portion 20a. can be effectively reduced. Therefore, since the bridge 20 has a shape in which the width w is widened on both sides in the longitudinal direction from the constricted portion 20a, leakage magnetic flux is reduced due to the presence of the constricted portion 20a, and the mechanical strength of the portion where the width w is widened is reduced. can be compatible with ensuring In a conventional general rotor 100 as shown in FIG. 7, the bridges 120 have a substantially uniform width w along the longitudinal direction a. If the width w of (see FIG. 9) is increased, the leakage magnetic flux in the bridge 120 will increase.

When the rotor 10 is rotated at high speed and centrifugal force is generated, bending stress is applied to the bridges 120 because the longitudinal direction a of the bridges 20 forms an angle with respect to the radial direction of the rotor core 11 . When the bridge 20 is provided with the narrowed portion 20a, the width w of the narrowed portion 20a is narrow, and depending on the specific shape of the bridge 20, the bending stress tends to concentrate on both sides of the narrowed portion 20a in the width direction. may become. For example, it is assumed that the radial edge 13c of the slot 13 and the radial edge 17c of the flux barrier 17 have angular shapes convex toward the inside of the bridge 20 at both widthwise ends of the constricted portion 20a. , the stress tends to be concentrated on the angular portion. Concentration of bending stress on a specific portion of the bridge 20 tends to reduce the mechanical strength at that portion. Then, it becomes difficult to rotate the rotor 10 at high speed.

However, in the present embodiment, as shown in FIG. 3, the radial edge 13c of the slot 13 and the radial edge 17c of the flux barrier 17 are formed in straight lines without corners at positions on both sides in the width direction of the constricted portion 20a. have. Therefore, even if the rotor 10 is rotated at a high speed, the stress is less likely to concentrate on both sides of the narrowed portion 20a in the width direction. Therefore, even if the narrowed portion 20a is provided in the bridge 20, it is easy to ensure sufficient mechanical strength to withstand high-speed rotation.

Furthermore, in the rotor 10 according to the present embodiment, due to the effect of the shape of the bridges 20, not only the narrowed portions 20a of the bridges 20 but also the diagonal portions can relieve stress concentration during high-speed rotation. In a conventional general rotor 100 as shown in FIG. 7 , at any of the four corners 113d, 113e, 117d, and 117e facing the bridge 120, manufacturing Only an R shape with a radius of curvature as small as required above is formed. As will be described later in the examples, when the rotor 100 is rotated at high speed, the bending stress is concentrated on the slot outer corner 113e and the barrier inner corner 117d, which face each other with a diagonal line b in the bridge 120. applied as This is because the direction of the diagonal line b connecting the slot outer corner 113e and the barrier inner corner 117d is close to the radial direction of the rotor core 111, which is the direction in which the centrifugal force is applied.

However, in the rotor 10 according to the present embodiment, the slot outer corner 13e and the barrier inner corner 17d facing each other with the bridge 20 interposed therebetween are rounded. Therefore, even if the rotor 10 is rotated at a high speed and a centrifugal force is applied to the rotor core 11 in the radial direction, the stress generated in the rotor core 11 by the centrifugal force is applied to the outer slot corners 13e, as will be described later. It is dispersed over a wide area within the bridge 20 without being locally concentrated in a narrow area of the inner barrier corner 17d.

In this way, by providing the slot outer corner 13e and the barrier inner corner 17d with the R shape so as not to concentrate the bending stress on a specific portion of the bridge 20, the bridge 20 has a mechanical strength that can withstand high-speed rotation. Makes it easier to maintain strength. It is no longer necessary to excessively increase the width w of the bridge 20 in order to ensure mechanical strength. By narrowing the width w of the bridge 20, particularly by providing a constricted portion 20a with a locally narrowed width w, leakage of effective magnetic flux in the bridge 20, that is, magnetic flux of the permanent magnet 16 and Magnetic flux leakage from the coil can be suppressed, torque reduction due to magnetic flux leakage can be suppressed, and magnet torque and reluctance torque of the motor 1 in which the rotor 10 is incorporated can be increased. As a result, the motor 1 can achieve both stable high-speed rotation and high output. Providing the slot outer corner portion 13e and the barrier inner corner portion 17d with the rounded shape is effective both in forming the narrowed portion 20a in the bridge 20 and in alleviating the concentration of bending stress on the diagonal portion, thereby stabilizing the structure. This contributes to achieving both high-speed rotation and high output.

From the viewpoint of sufficiently obtaining these effects, it is preferable that the radius of curvature of the R-shape of the slot outer corner 13e and the barrier inner corner 17d is 25% or more of the radial length lm of the slot 13. FIG. On the other hand, if the radius of curvature of the rounded corners 13e and 17d is too large, stress concentration tends to occur on both sides of the bridge 20 in the width direction. is preferred. Further, when the direction of the R-shaped tangents of the slot outer corner 13e and the barrier inner corner 17d is closer to the radial direction of the rotor core 11 on which the centrifugal force acts, the effect of dispersing the stress is excellent. It is preferable that the direction is within a range of about ±180°/[number of poles] with respect to the radial direction of the rotor core 11 . Note that the number of poles is eight in this embodiment.

Furthermore, in the present embodiment, as described above, the radius of curvature of the R shape of the barrier inner corner 17d is larger than the radius of curvature of the R shape of the slot outer corner 13e. The flux barrier 17 has a portion where the radial length Lm is larger than the radial length lm of the slot 13. Under such circumstances, the radius of curvature of the R-shaped barrier inner corner 17d is increased. Thus, in the bridge 20, the concentration of the bending stress can be effectively alleviated while providing a long region with a narrow width w along the longitudinal direction a.

If the radial length Lm of the flux barrier 17 is about the same as the radial length lm of the slot 13, and the radius of curvature of the R-shaped barrier inner corner 17d is about as small as the slot outer corner 13e, Then, as indicated by the dotted line s in FIG. 3, the outer edge of the barrier inner corner portion 17d passes largely inside the radial direction edge 17c (indicated by arrow s1). On the other hand, by increasing the radius of curvature of the R-shaped barrier inner corner portion 17d as indicated by the solid line, the outer edge of the barrier inner corner portion 17d passes through a position close to the radial edge 17c. Therefore, the narrow region of the bridge 20 continues along the longitudinal direction a. Leakage of effective magnetic flux, such as the magnetic flux of the permanent magnets 16, in the bridge 20 can then be reduced. Both the reduction in magnetic flux leakage due to the narrow width w of the bridge 20 and the effective relaxation of the bending stress concentration on the inner barrier corner 17d due to the large radius of curvature of the R shape are achieved.

From the viewpoint of sufficiently obtaining the above effect, it is preferable that the radius of curvature of the R shape of the barrier inner corner 17d is at least twice the radius of curvature of the R shape of the slot outer corner 13e. On the other hand, from the viewpoint of avoiding the saturation of the above effects and the excessive increase in the radius of curvature of the barrier inner corner 17d, which instead causes stress concentration on the bridge 20, the R-shaped curvature of the barrier inner corner 17d is The radius is preferably suppressed to 25 times or less the radius of curvature of the R-shaped slot outer corner 13e.

In this embodiment, as described above, not only the slot outer corner 13e and the barrier inner corner 17d but also the slot inner corner 13d and the barrier outer corner 17e are provided with the R shape. The radius of curvature is smaller than the curvature radius of the R shape of the slot outer corner 13e and the barrier inner corner 17d. Bending stress caused by the rotation of the rotor 10 tends to concentrate on the slot outer corner 13e and the barrier inner corner 17d located on the diagonal line b oriented in a direction close to the radial direction of the rotor core 11 due to their arrangement. Therefore, forming the corners 13e and 17d in a rounded shape is effective in alleviating stress concentration, but the slot inner corner 13d and the barrier outer corner 17e are arranged so that stress is difficult to concentrate in the first place. Therefore, it is not necessary to form an R shape for the same purpose. Rather, even when the slot inner corner 13d and the barrier outer corner 17e are provided with an R shape, it is better to keep the radius of curvature small so that the outer edges of the corners 13d and 17e are aligned with the slot 13 and the flux barrier. Since the amount of retraction toward the inside of the bridge 17 becomes smaller, the width w of the bridge 20 can be kept small over the entire length in the longitudinal direction a. This makes it easier to reduce magnetic flux leakage in the bridge 20 . The radius of curvature of the rounded shape of the slot inner corner 13d and the barrier outer corner 17e is preferably 75% or less of the curved radius of curvature of the slot outer corner 13e. The slot inner corner portion 13d and the barrier outer corner portion 17e may have an angular shape that does not have an R shape.

As described above, in the bridge 20 provided between the slot 13 of the rotor 10 and the flux barrier 17, by providing the narrowed portion 20a having a narrow width w, the magnetic flux of the permanent magnet 16 becomes effective. The magnetic flux leakage in the bridge 20 can be reduced and the magnet torque and reluctance torque of the motor 1 can be increased. By forming the rounded shape at the slot outer corner 13e and the barrier inner corner 17d, it is possible to easily form the constricted portion 20a. stress concentration during high-speed rotation, which is likely to occur due to excessive rotation, can be alleviated, and the rotational speed of the motor 1 can be increased to the high-speed side. By increasing the radius of curvature of the R shape particularly at the inner barrier corner 17d and further decreasing it at the inner slot corner 13d and the outer barrier corner 17e, together with the effect of forming the narrowed portion 20a, Leakage of effective magnetic flux such as the magnetic flux of the permanent magnets 16 in the bridge 20 can be reduced, and the magnet torque and reluctance torque of the motor 1 can be improved. As a result, by providing the flux barrier 17 with a portion having a radial length Lm larger than the radial length lm of the slot 13, the output torque of the motor 1 is improved together with the effect of improving the reluctance torque. can be made In this way, the effect of the shape of the flux barrier 17 and the bridge 20 makes it possible to simultaneously achieve stabilization of high-speed rotation and high output of the motor 1 .

(3) Arrangement of Bridge in Flux Barrier Midway Portion Further, in the rotor 10 according to the present embodiment, the bridge 21 is formed in the midway portion of the flux barrier 17 along the circumferential direction. The bridge 21 connects the outer peripheral portion and the inner peripheral portion of the flux barrier 17 and is formed integrally with the rotor core 11 . The flux barrier 17 is circumferentially divided into two by the bridge 21 . In the illustrated embodiment, the bridge 21 is provided along the d-axis of the rotor at the center of the flux barrier 17 in the circumferential direction.

By providing the bridge 21 in the middle of the flux barrier 17, the mechanical strength of the rotor core 11 can be increased. In particular, it is effective in reducing the bending stress applied to each part of the rotor core 11 when the rotor 10 is rotated at high speed.

The flux barrier 17 is provided at a position between the innermost slots 13 divided into two in the circumferential direction. extends in a direction closer to the radial direction of the rotor core 11 than the bridge 20 provided between the flux barrier 17 and the slot 13 . Then, as the stress applied by the centrifugal force when the rotor 10 rotates, in the bridge 20 between the flux barrier 17 and the slot 13, the bending stress component, that is, the component along the circumferential direction of the rotor core 11 is large. Therefore, in the bridge 21 provided in the middle of the flux barrier 17, the tensile stress component, that is, the component along the radial direction of the rotor core 11 increases. As in the illustrated embodiment, when the bridge 21 is provided at the center of the flux barrier 17 in the circumferential direction, the direction of the bridge 21 coincides with the radial direction of the rotor core 11 (rotor d-axis). Only tensile stress is applied. In the rotor core 11, if a bending stress is applied to a narrow portion such as the bridges 18 to 21, the mechanical strength of the material is likely to be reduced or deformed. Even if it is, those situations are unlikely to occur.

Therefore, by providing a bridge 21 in the middle of the flux barrier 17 and distributing part of the stress applied to the rotor core 11 by the centrifugal force when the rotor 10 rotates as tensile stress applied to the bridge 21, , the bridge 20 between the slot 13 and the flux barrier 17, as well as the narrow width of the portion where the mechanical strength tends to be low, the stress, particularly the bending stress, can be dispersed. As a result, the rotor core 11 as a whole can easily ensure mechanical strength that can withstand high-speed rotation. The total width of both bridges 20 and 21 is narrowed compared to the case where the bridge 20 is formed wide between the slot 13 and the flux barrier 17 without providing the bridge 21 in the circumferential direction middle portion of the flux barrier 17. However, equivalent mechanical strength can be ensured.

In the illustrated embodiment, only one bridge 21 is provided at the center of the flux barrier 17 in the circumferential direction. It may be configured to provide a bridge 21 . Conversely, when the need for stress distribution is low, the bridge 21 may not be provided in the middle of the flux barrier 17 in the circumferential direction. In this case, as shown as a modified rotor 10' in FIG. 4, one circumferentially continuous flux barrier 17' is provided symmetrically across the rotor d-axis. A portion having a long radial length Lm continues in the circumferential direction across the rotor d-axis.

In the form shown in FIG. 3, the corners 17f and 17g of the flux barrier 17 on both sides facing the bridge 21 are also rounded. This makes it easier to achieve both the narrow width of the bridge 21 and the avoidance of breakage of the bridge 21 due to stress concentration on these corners 17f and 17g. In addition, in the process of working the steel plate in the manufacture of the rotor 10, the bridges 21 can be easily machined using currently conceivable working machines.

[2] Second Embodiment As a bridge between the slot and the flux barrier, a constricted portion having the smallest dimension in the width direction along the adjacent direction of the slot and the flux barrier is provided. In addition, on both sides of the constricted portion in the width direction, the edges of the slots and flux barriers are linear or bridge-like. As long as the curved shape is convex toward the inside in the width direction, it is not limited to the bridge having the specific shape shown in the first embodiment, and the leakage of magnetic flux that is effective in the bridge can be reduced and the bridge can be constricted. stress concentration on both sides in the width direction of the portion can be alleviated. A case where the permanent magnet rotors 10A and 10B according to the second and third embodiments of the present invention have bridges having a shape different from that of the permanent magnet rotor 10 according to the first embodiment will be described below. do.

In the following, the parts different from the first embodiment will be mainly described, and the common parts will be denoted by corresponding reference numerals in the drawings, and detailed description thereof will be omitted. Further, the permanent magnet rotors 10A and 10B according to the second embodiment and the third embodiment can also constitute the rotary electric machine 1, like the permanent magnet rotor 10 according to the first embodiment. .

FIG. 5 shows the state in the vicinity of the flux barrier 17A of the permanent magnet rotor 10A according to the second embodiment of the invention. In the permanent magnet rotor 10 according to the first embodiment, as shown in FIG. 3, the radial edge 17c of the flux barrier 17 is formed as a substantially linear edge. A barrier inner corner 17d having an R shape was formed between 17c and the inner peripheral side edge 17b. On the other hand, in the permanent magnet rotor 10A according to the second embodiment, in the flux barrier 17A, the entire radial edge 17c facing the slot 13A has a curvilinear shape convex toward the inside of the bridge 20A. Specifically, it has a substantially arc shape.

The width w of the bridge 20A is the narrowest at a position corresponding to the middle portion of the substantially arc-shaped radial edge 17c, forming a narrowed portion 20a. On both sides of the narrowed portion 20a in the width direction, the radial edge 17c of the flux barrier 17A and the rounded edge of the slot outer corner 13e of the slot 13A face each other. The substantially arc shape of the radial edge 17c of the flux barrier 17A, the rounded shape of the slot outer corner 13e of the slot 13A, and the inclined shape of the radial edge 13c toward the inner side of the slot 13A toward the inner peripheral side make the bridge 20A has a shape in which the width w gradually widens on both sides along the longitudinal direction a from the constricted portion 20a.

Thus, also in the rotor 10A according to the second embodiment, as in the rotor 10 according to the first embodiment, the bridges 20A provided between the mutually adjacent slots 13A and the flux barriers 17A have widths It has a constricted portion 20a with a narrowed width w, and has a shape in which the width w gradually widens on both sides along the longitudinal direction a from the constricted portion 20a. Since the bridge 20A has such a shape, it is possible to reduce the leakage of the effective magnetic flux at the bridge 20A due to the presence of the constricted portion 20a and to secure the mechanical strength due to the widened portion of the width w. . As a result, it is possible to achieve both stabilization of high-speed rotation and high output.

Further, in the rotor 10A according to the second embodiment, the edge of the slot outer corner 13e of the slot 13A and the radial edge 17c of the flux barrier 17A are located on both sides in the width direction of the narrowed portion 20a of the bridge 20A. facing. Both the slot outer corner 13e and the radial edge 17c have a curved shape convex toward the inside of the bridge 20A at the position of the narrowed portion 20a. In this way, the edges facing both sides in the width direction of the constricted portion 20a have a curvilinear shape that protrudes toward the inner side in the width direction of the bridge. As with the rotor 10 according to the first embodiment, which has a linear shape, it is possible to alleviate the concentration of stress on both sides of the narrowed portion 20a in the width direction during rotation of the rotor.

As described above, in the flux barrier 17A of the rotor 10A according to the second embodiment, the entire radial edge 17c is formed in a substantially arc shape, and the radial edge 17c and the inner peripheral edge The gap 17b is joined by an inclined edge 17h that is inclined inwardly of the flux barrier 17A toward the inner peripheral side. Even in such a case, as in the first embodiment, the diagonal line b defined as a tangent along the direction of the centrifugal force circumscribing the R shape of the slot outer corner 13e passes through the bridge 20A, A position that intersects the edge of the flux barrier 17A is defined as an inner barrier corner 17d, and in the first embodiment, for the outer slot corner 13e, the preferred form described with respect to curvature and the like can be applied. In the embodiment shown in FIG. 5, a portion of the radial edge 17c having a substantially arc shape on the inner peripheral side serves as the barrier inner corner 17d defined in this manner.

As described above, in the flux barrier 17/17A, as in the first embodiment, the radial edge 17c is formed linearly, and the inner peripheral edge of the flux barrier 17c is rounded to form a barrier inner corner. 17d or, as in the second embodiment, the entire radial edge 17c is formed into a substantially arc shape including the barrier inner corner 17d as a part thereof. By providing the constricted portion 20a whose edges on both sides in the direction are linear or convex curved toward the width direction inner side of the bridge 20/20A, the stress applied to both ends of the constricted portion 20a in the width direction can be reduced. Leakage flux in bridge 20/20A can be reduced while avoiding concentrations. In the second embodiment, the radial edge 17b, the inclined edge 17h, and the inner peripheral side edge 17b are arranged in a series. The flux barrier 17A, which is joined in a smooth shape and has a portion with an increased radial length Lm, is easier to configure with a smoother edge than in the first embodiment.

[3] Third Embodiment Finally, a permanent magnet rotor 10B according to a third embodiment of the present invention will be described. FIG. 6 shows the state near the flux barrier 17B of the permanent magnet rotor 10B according to the third embodiment.

Also in the third embodiment, the bridge 20B has a constriction 20a with the narrowest width w. The width w gradually widens from the constricted portion 20a to both sides along the longitudinal direction a.

A radial edge of the flux barrier 17B facing one side in the width direction of the bridge 20B has two linear portions 17c1 and 17c2. The first linear portion 17c1 is located on the outer peripheral side of the constricted portion 20a, and is formed of a straight line that slopes toward the inner side of the flux barrier 17B toward the outer peripheral side. The second linear portion 17c2 is located on the inner peripheral side of the constricted portion 20a, and is formed of a straight line that slopes toward the inside of the flux barrier 17B toward the inner peripheral side. In other words, the two linear portions 17c1 and 17c2 are mutually arranged in a substantially V-shape. However, the two linear portions 17c1 and 17c2 do not form angular vertexes at the joints of the two linear portions 17c1 and 17c2, but instead form an R shape that protrudes toward the inside of the bridge 20B. It is smoothly joined by the joint portion 17c3.

A radial edge of the slot 13B facing the other side in the width direction w of the bridge 20B also has two linear portions 13c1 and 13c2. The first linear portion 13c1 is located on the outer peripheral side of the constricted portion 20a, and is formed of a straight line that slopes toward the inner side of the slot 13B toward the outer peripheral side. The second linear portion 13c2 is located on the inner peripheral side of the constricted portion 20a, and is formed of a straight line that slopes toward the inside of the slot 13B as it goes toward the inner peripheral side. In other words, the two linear portions 13c1 and 13c2 are mutually arranged in a substantially V shape. However, the two linear portions 13c1 and 13c2 do not form angular vertexes at the junctions of the two linear portions 13c1 and 13c2. It is smoothly joined by the joint portion 13c3.

In this way, in the bridge 20B, on both sides in the width direction along the longitudinal direction a, the width direction edge of the flux barrier 17B made up of the straight portions 17c1 and 17c2 and the width direction of the slot 13B made up of the straight portions 13c1 and 13c2 are arranged. Since the edge is provided, the bridge 20B spreads in a widening manner on both sides along the longitudinal direction a centering on the constricted portion 20a. By using the linear portions 17c1, 17c2, 13c1, and 13c2 in this way, it is easy to form a change in the width w along the longitudinal direction a in the bridge 20B. It becomes easier to design the bridge 20B that can ensure the mechanical strength of the portion where w is widened.

The two linear portions (between the linear portions 17c1 and 17c2, and between the linear portions 13c1 and 13c2) are smoothly joined by the joint portions 17c3 and 13c3 having an R shape, so that the above-described As in the second embodiment, the edges of the slots 13B and the flux barriers 17B on both widthwise sides of the constricted portion 20a are in a curved shape that protrudes inward in the widthwise direction of the bridge 20B. . As a result, it is possible to alleviate the concentration of stress on both sides of the narrowed portion 20a in the width direction when the rotor 10B rotates.

The present invention will be described in detail below using examples.

<Analysis of stress distribution>
First, we analyzed the distribution of the stress applied to each part of the rotor core due to the rotation of the rotor when the shapes of the flux barriers and bridges provided in the rotor core were changed. Analysis was performed using a structural analysis program.

(analysis method)
The following four types of rotor models were prepared.
Conventional configuration A: As shown in FIG. 7, a rotor having a general configuration in which the flux barrier is formed in an arc shape having the same radial length as the slot was employed. The width w of the bridge 120 between the flux barrier 117 and the slot 113 is substantially the same as the width w of the narrowed portion in Embodiments A and B, which will be described later.
- Conventional configuration B: Based on the above-described conventional configuration A, the width w of the bridge 120 between the flux barrier 117 and the slot 113 is increased by about two times.
- Embodiment A: The rotor according to the second embodiment of the present invention shown in Fig. 5 was adopted. The flux barrier 17A has a portion with a larger radial length than the slot 13A. The flux barrier 17A has a substantially arcuate radial edge 17c. A bridge 21 is formed in the middle of the flux barrier 17A.
- Embodiment B: The rotor according to the third embodiment of the present invention shown in Fig. 6 was adopted. The flux barrier 17B has a portion with a larger radial length than the slot 13B. Each of the flux barrier 17B and the slot 13B has two linear portions (17c1 and 17c2, 13c1 and 13c2) smoothly joined by R-shaped joint portions 17c3 and 13c3 on the radial edges. there is A bridge 21 is formed in the middle of the flux barrier 17B.
As described above, the width w of the narrowest portion (constricted portion) of the bridge between the slot and the flux barrier is substantially the same in Conventional Form A and Embodiments A and B. In Conventional Form B, about twice as many.

The distribution of the stress applied to each part of the rotor due to the centrifugal force when the rotors of the above-described conventional forms A and B and the embodiments A and B were rotated was analyzed. Table 1 summarizes the parameters used in the simulation.

(result)
8 to 11 show the analysis results for each form. 8 shows the results of conventional form A, FIG. 9 shows the results of conventional form B, FIG. 10 shows the results of embodiment A, and FIG. In each figure, the magnitude of the applied principal stress (unit: MPa) is displayed in grayscale, and the greater the stress, the darker the color.

Looking at the results for Conventional Configuration A in FIG. 8, large stresses are distributed at specific locations in the bridge between the slot and the flux barrier. Specifically, large stresses are localized in narrow regions at the upper right and lower left corners of the bridge, corresponding to the outer slot corners and the inner barrier corners. The maximum stress at these sites is 510 MPa.

Looking at the results of Conventional Form B in FIG. 9, the tendency of stress to concentrate in specific areas in the bridge between the slot and the flux barrier is reduced. The maximum value of the stress is observed near the center of the radial edge of the flux barrier, which is 300 MPa, which is smaller than that of the conventional form A described above. It can be interpreted that this is the result of widening the width of the bridge compared to the case of the conventional form A, so that the stress is distributed over a large area in the bridge.

Furthermore, looking at the results of embodiment A in FIG. 10, each bridge is subjected to a higher stress than the regions other than the bridge. status is not visible. A relatively large stress is distributed in the bridge in the middle of the flux barrier, and a smaller stress is distributed in the bridge between the slot and the flux barrier.

As shown in the enlarged view of FIG. 10(b), in the bridge between the slot and the flux barrier, other regions are added to the upper right and lower left regions of the bridge, which correspond to the outer corner of the slot and the inner corner of the barrier. However, the degree of stress concentration is remarkably smaller than in the case of the conventional form A in FIG. Moreover, the maximum value of the stress at the outer corner of the slot and the inner corner of the barrier is 275 MPa, which is suppressed to 54% of the maximum value in the conventional form A. The maximum value of the stress is smaller than that of the conventional form B in which the width of the bridge is widened. Behavior such as concentration of stress on both sides in the width direction of the constricted portion where the width is the narrowest in the bridge was not observed.

As described above, a relatively large stress is distributed in the bridge provided in the middle of the flux barrier. The distribution of the stress is highly uniform across the entire surface, and no state in which a large stress is distributed at a specific position is observed. The maximum value of stress in this bridge is 290 MPa.

Thus, in the embodiment A of FIG. 10, compared with the conventional embodiment A of FIG. , and the concentration of stress on the slot outer corner and the barrier inner corner can be alleviated. This is mainly due to the fact that stress is dispersed inside the bridge between the slot and the flux barrier due to the curvilinear shape of the edges on both sides in the width direction of the constriction and the R shape of the outer corner of the slot and the inner corner of the barrier. , and the application of tensile stress to the bridge provided in the middle of the flux barrier reduces the stress applied to other portions.

Looking at the result of embodiment B shown in FIG. 11, in the bridge between the slot and the flux barrier, a slightly larger stress is applied to the positions on both widthwise sides of the narrowest constriction. However, the degree of stress concentration is significantly smaller than the concentration of stress on the outside corners of the slot and the inside corners of the barrier in the case of the conventional form A in FIG. The maximum value of the stress on both widthwise sides of the constricted portion is 295 MPa, which is suppressed to 58% of that in the case of the conventional form A. Compared to the embodiment shape A in FIG. 10, the shape of the edges on both sides in the width direction of the bridge abruptly changes in the vicinity of the narrowed portion, so that a large stress is generated at the positions on both sides in the width direction of the narrowed portion. However, the edges on both sides of the constricted portion in the width direction are curved, instead of convex angular shapes toward the inside of the bridge, so that the degree of stress concentration is small. If it is suppressed, it can be interpreted.

<Motor output characteristics>
A simulation was performed on the rotors of the above-described conventional forms A and B and the embodiment A to analyze the torque characteristics and the output characteristics. The simulation was performed by electromagnetic field analysis using the finite element method (FEM).

The parameters in Table 1 above were used for the simulation. Moreover, the inverter DC voltage was set to 650V.

(result)
12 and 13 show analysis results of torque characteristics. FIG. 12(a) shows the results of the conventional type A, FIG. 12(b) shows the results of the conventional type B, and FIG. Total torque is shown along with magnet torque and reluctance as a function of current phase angle, respectively. In both figures, the torque values are normalized with the maximum value of the total torque in the conventional configuration B of FIG. 12(b) set to 1.

Comparing the conventional embodiment A shown in FIG. 12(a) and the embodiment A shown in FIG. 13, both the magnet torque and the reluctance torque are increased in the embodiment A, and as a result, the total torque is also increased. . The total torque, at its maximum value, is about 4% larger than that of conventional form A. It is interpreted that the improvement in reluctance torque in Embodiment A is a result of the flux barrier having a portion of greater radial length than the slot. Furthermore, in embodiment A, the bridge between the slot and the flux barrier is provided with a constriction that is abruptly narrower than the rest of the bridge, so that the flux of the permanent magnets in the bridge and the coils of the stator It is interpreted that the leakage of the magnetic flux from the magnet is reduced, and the magnet torque and the reluctance torque are improved. As described above, in Embodiment A, torque is improved by providing the flux barrier with a portion having a large radial length and by providing a constricted portion in the bridge between the slot and the flux barrier. It is possible to ensure both the mechanical strength shown by the simulation and compatibility.

On the other hand, looking at the torque characteristics of the conventional form B in FIG. It's getting smaller. As a result, the total torque is also small. The total torque, at its maximum value, is about 3% smaller than that of conventional form A. This can be interpreted to be due to the increase in the width of the bridge between the slots and the flux barrier, which increases the leakage of the magnetic flux of the permanent magnets in this bridge and the magnetic flux from the stator coils. In other words, in a conventional general rotor in which the width of the bridge between the slot and the flux barrier is substantially constant, increasing the width of the bridge in order to reduce the stress applied to the bridge reduces the torque that can be obtained. Therefore, it can be said that it is difficult to achieve both securing of mechanical strength and improvement of torque.

FIG. 14(a) shows the torque characteristics (dimension: Nm) when the maximum torque is generated as a function of the rotational speed of the rotor, and compares the conventional forms A and B with the embodiment A. FIG. Again, the results are normalized so that the maximum value in the conventional form B is 1.

According to FIG. 14(a), in the entire speed range, in the embodiment A, a larger torque than in the conventional embodiments A and B is obtained. Comparing the maximum values, in the embodiment A, the value is about 7% larger than the conventional type B, and even when the conventional type A is used as the standard, the value is about 3% larger.

Further, FIG. 14(b) shows the output characteristics (dimension: W) as a function of the rotational speed of the rotor, and compares the conventional forms A and B with the embodiment A. As shown in FIG. Again, the results are normalized so that the maximum value in the conventional form B is 1.

According to FIG. 14(b), a larger output is obtained in the embodiment A than in the conventional embodiments A and B in all speed ranges. The maximum output of the embodiment A is about 8% higher than that of the conventional type B, and is about 5% higher than that of the conventional type A as well. In addition, the output at the maximum speed shown in the figure is about 18% larger than the conventional type B in the embodiment A, and about 10% larger than the conventional type A as well. ing. As the rotation speed increases, the difference in the value of the embodiment A from the values of the conventional embodiments A and B increases.

Thus, the torque characteristics and output characteristics as a function of rotational speed in FIGS. 14(a) and 14(b) match well with the torque characteristics as a function of current phase angle shown in FIGS. 12 and 13. It's becoming From these results, as in Embodiment A, by providing the flux barrier with a portion having a large radial length and providing a constricted portion in the bridge between the slot and the flux barrier, the conventional Embodiments A and B can be obtained. , compared to the case where the radial length of the flux barrier is equal to the slot and the width of the bridge between the slot and the flux barrier is substantially uniform, the torque and output characteristics can be improved. I understand.

Finally, FIG. 15 shows a comparison of the number of winding magnetic flux linkages of the permanent magnet magnetic flux between the embodiment A and the conventional forms A and B. As shown in FIG. Here, the value of embodiment A is normalized as 1, and the number of magnetic flux linkages of each form is shown.

The larger the number of flux linkages, the larger the magnetic flux formed by the permanent magnets at the coils of the stator, and the smaller the leakage flux in the rotor core bridges and the like. According to FIG. 15, the number of magnetic flux linkages is the largest in the embodiment A, the smaller in the conventional form A, and the smaller in the conventional form B. FIG. Based on the value of the embodiment A, in the conventional form B, the number of magnetic flux linkages is reduced by about 8%. This result has a correlation with the shape of the bridge between the slot and the flux barrier, and it can be said that the leakage of the magnetic flux is increased in the conventional configuration B having the wide bridge. In the conventional embodiment A and the embodiment A, in which the width of the bridge is small, the leakage of the magnetic flux is suppressed. It can be said that leakage is effectively suppressed.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications are possible without departing from the gist of the present invention.

In the permanent magnet rotor 10 (10A, 10B) and the rotary electric machine 1 according to the above-described embodiment of the present invention, the object is to give a large reluctance torque, and the gap between the plurality of slots 13 (13A, 13B) is The positioned flux barrier 17 (17A, 17B) is located at a portion where the distance Lm between the inner peripheral edge and the outer peripheral edge of the rotor core 11 is greater than the distance lm of the slots 13 (13A, 13B). However, in the bridge 20 (20A, 20B) provided between the slot 13 (13A, 13B) and the flux barrier 17 (17A, 17B), stress concentration at a specific site When the task is to relax, a flux barrier having an arbitrary distance Lm is formed, and "(2) the shape of the bridge" and "(3) arrangement of the bridge in the middle of the flux barrier" are described above. The configuration of each bridge 20 (20A, 20B), 21 described can be employed.

1 motor (rotary electrical machine)
10, 10A, 10B rotor (permanent magnet rotor)
11 rotor core 12 hollow portions 13, 14, 15 slots 13A, 13B slot 13a (slot) outer peripheral edge 13b (slot) inner peripheral edge 13c (slot) radial edge 13d slot inner corner 13e slot Outer corner 16 Permanent magnets 17, 17A, 17B Flux barrier 17a (flux barrier) outer peripheral edge 17b (flux barrier) inner peripheral edge 17c (flux barrier) radial edge 17d barrier inner corner 17e Barrier outer corner 17h Inclined edges 18, 19 Bridges 20, 20A, 20B Bridge 21 Bridge 30 Stator (stator)
a Bridge longitudinal direction b Bridge diagonal d′ Rotor d axis lm Slot radial length Lm Flux barrier radial length w Bridge width

Claims (4)

A permanent magnet rotor having a rotor core and permanent magnets embedded in the rotor core and forming magnetic poles,
The rotor core has a plurality of slots in which the permanent magnets are embedded in a circumferential direction of the rotor core,
having a flux barrier as a gap in which the permanent magnet is not embedded at a position between the plurality of slots;
The flux barrier has a portion in which the distance between the inner peripheral edge and the outer peripheral edge of the rotor core is greater than the distance of the slot,
Adjacent two slots among the plurality of slots have an inner peripheral edge of the rotor core and an outer peripheral edge of the rotor core each formed into a convex circular arc shape toward the inside of the rotor core. is formed as a segmented one, the flux barrier is formed at a position between two adjacent slots,
In the flux barrier, a first bridge that connects an outer peripheral portion and an inner peripheral portion of the flux barrier is formed integrally with the rotor core in a circumferentially intermediate portion of the rotor core, and the first bridge is formed integrally with the rotor core. The corners of the flux barrier on both sides facing the bridge of are provided with an R shape,
Between the slots and the flux barriers that are adjacent to each other, a second bridge that connects an outer peripheral side portion and an inner peripheral side portion of the rotor core is formed integrally with the rotor core,
In a cross section orthogonal to the rotation axis of the rotor core, the second bridge has a constricted portion having the smallest dimension in the width direction along the adjacent direction of the slot and the flux barrier, and from the constricted portion, having a shape in which the dimension in the width direction gradually widens on both sides along the direction intersecting the width direction;
On both sides of the narrowed portion in the width direction, the edges of the slot and the flux barrier have a straight shape or a curved shape that is convex toward the inside in the width direction of the second bridge,
A slot outer corner, which is a corner on the outer peripheral side of the slot facing the second bridge, has an R shape,
The barrier inner corner at a position where a tangent along the direction of centrifugal force circumscribing the R shape of the slot outer corner intersects the edge of the flux barrier through the second bridge has an R shape. and
The inner corner of the slot, which is the corner on the inner peripheral side of the slot, and the outer corner of the barrier, which is the corner on the outer peripheral side of the flux barrier, which are opposed to each other with the second bridge interposed therebetween also have rounded shapes. is formed and
a curvature radius of the R shape is larger at the barrier inner corner and the slot outer corner than at the slot inner corner and the barrier outer corner;
The permanent magnet rotor, wherein the curvature radius of the R shape of the slot inner corner and the barrier outer corner is 75% or less of the curvature radius of the R shape of the slot outer corner. 2. The permanent magnet rotor according to claim 1, wherein the radius of curvature of the R shape of the inner barrier corner is larger than the radius of curvature of the R shape of the outer corner of the slot. When the number of poles of the permanent magnet rotor is described as [number of poles],
3. A direction of a tangent line of the R-shape of the outer corner of the slot and the inner corner of the barrier is within a range of ±180°/[number of poles] with respect to the radial direction of the rotor core . A permanent magnet rotor as described in . A rotary electric machine comprising a permanent magnet rotor according to any one of claims 1 to 3 .

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