Rotary electric machine

Abstract

In a rotary electric machine in which the number of slots in each pole and each phase is four or more and armature windings are configured as distributed windings, flux barriers (63IN) are formed as flux barriers adjacently to each of both ends, in the circumferential direction, of first permanent magnets (62IN) constituting each magnetic pole. Given P1 as the center angle of the arc connecting circumferential-direction centers of slots (51S) adjacent to each other in the circumferential direction, the rotary electric machine is configured to ensure a first condition that center angle θ１with respect to a rotation center O of a first arc portion (61M1) constituting an outer circumferential surface outward in a radial direction of a rotor core (61) in which the flux barrier (63IN) is not formed between the magnetic poles adjacent in the circumferential direction, is θ１= P1 x 2.1 or less. Note that P1 is the center angle of an arc connecting circumferential-direction centers of slots adjacent to each other in the circumferential direction.

Description

rotating electrical machines

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

[0002] Rotating electric machines such as motors and generators for EVs (Electric Vehicles) and HEVs (Hybrid Electric Vehicles) are required to be smaller, more efficient, and have lower noise vibration (NV) from the viewpoints of resource conservation, extending the vehicle's driving range, quietness, etc. To achieve this, traction motors have been disclosed as rotating electric machines, such as the one described below, in which the stator has a multi-slot structure to suppress magnetic flux fluctuations in the air gap between the stator and rotor, thereby reducing torque ripple, cogging torque, etc.

[0003] That is, in a traction motor as a conventional rotating electric machine, a first plurality of magnet pairs are configured in a laminate stack and arranged in a first V-shape. Also, a second plurality of permanent magnets, each larger than each of the first plurality of permanent magnets, are configured as a second plurality of magnet pairs in the laminate stack and arranged in a second V-shape. The separation angle of the second magnet pairs is configured to be smaller than the separation angle of the first magnet pairs (see, for example, Patent Document 1).

[0004] JP 2020-68654 A (FIGS. 3 and 4)

[0005] In the above-mentioned conventional traction motor, a method has been proposed in which the stator employs a multi-slot structure with four slots per pole per phase, and the size and arrangement angle of the permanent magnets embedded in the rotor, which is a laminated stack, are adjusted to reduce cogging torque. However, while such motors can reduce cogging torque, they also increase stator iron loss, potentially reducing motor efficiency. In particular, a multi-slot structure with a large number of slots per pole per phase increases the number of teeth between the rotor poles, resulting in a significant increase in the aforementioned iron loss and reduced motor efficiency. This application discloses technology to solve the above-mentioned problems and aims to provide a highly efficient rotating electric machine, even in a multi-slot structure with a large number of slots per pole per phase.

[0006] The present application discloses a rotating electric machine comprising: a stator having a plurality of teeth protruding radially inward from an annular yoke portion, with an armature winding wound in a plurality of slots formed between the teeth, and a rotor having a rotor core on which a plurality of magnetic poles constituted by permanent magnets and flux barriers are formed, wherein the number of slots per pole per phase, obtained by dividing the total number of the slots by the number of phases and the number of magnetic poles of the rotor, is four or more, and the armature winding is configured as a distributed winding, wherein first flux barriers are formed adjacent to both circumferential ends of first permanent magnets constituting each of the magnetic poles, and a first arc portion constituting the radially outer outer peripheral surface of the rotor core on which no flux barrier is formed between circumferentially adjacent magnetic poles is configured to satisfy a first condition that θ1 = P1 × 2.1 or less, where P1 is the central angle of the arc connecting the circumferential centers of the circumferentially adjacent slots.

[0007] According to the rotating electric machine disclosed in the present application, a highly efficient rotating electric machine can be obtained even in a multi-slot structure having a large number of slots per pole per phase.

[0008] FIG. 1 is a schematic diagram showing a cross section parallel to the axial direction of a rotating electric machine according to embodiment 1. FIG. 2 is a diagram showing a portion of a cross section perpendicular to the axial direction of the rotating electric machine according to embodiment 1. FIG. 3 is a cross section perpendicular to the axial direction Y of a rotating electric machine of a comparative example. FIG. 4 is a cross section perpendicular to the axial direction Y of a rotating electric machine of a comparative example. FIG. 5 is a cross section perpendicular to the axial direction Y of a rotating electric machine of a comparative example. FIG. 6 is a cross section perpendicular to the axial direction Y of a rotating electric machine of a comparative example. FIG. 7 is a diagram showing a graph of iron loss characteristics of a rotating electric machine when the central angle θ1 is changed. FIG. 8 is a diagram explaining the principle of iron loss increase in a rotating electric machine. FIG. 9 is a diagram showing a portion of a cross section perpendicular to the axial direction of a rotating electric machine according to embodiment 1. FIG. 10 is a cross section perpendicular to the axial direction Y of a rotating electric machine of a comparative example. FIG. 11 is a cross section perpendicular to the axial direction Y of a rotating electric machine of a comparative example. FIG. 10 is a diagram showing a part of a cross section perpendicular to the axial direction of a rotating electric machine according to embodiment 2. FIG. 11 is a diagram showing a part of a cross section perpendicular to the axial direction of a rotating electric machine according to embodiment 2. FIG. 12 is a diagram showing a part of a cross section perpendicular to the axial direction of a rotating electric machine according to embodiment 2. FIG. 13 is a diagram showing a part of a cross section perpendicular to the axial direction of a rotating electric machine according to embodiment 2. FIG. 14 is a diagram showing a magnetomotive force distribution in a rotating electric machine. FIG. 15 is a diagram showing a magnetomotive force distribution in a rotating electric machine.

[0009] First Embodiment A rotating electric machine according to a first embodiment will now be described with reference to the drawings. In the drawings, the directions in the annular rotating electric machine are indicated as a circumferential direction C, a radial direction X, and an axial direction Y. Fig. 1 is a schematic diagram showing a cross section parallel to the axial direction Y of a rotating electric machine 100 according to the first embodiment.

[0010] 1 , the rotating electric machine 100 includes a cylindrical housing 70, a stator 50 accommodated therein, and a rotor 60 arranged coaxially with the stator 50 on the radially inner side X1 of the stator 50. The housing 70 has a cylindrical frame 71 with a bottom and an end plate 72 that closes an opening of the frame 71. The stator 50 is fixed to the frame 71 in a state of being fitted inside the frame 71 on the radially inner side X1. The rotor 60 is rotatably supported by a rotating shaft 74 provided via a bearing 73 at the center of the end plate 72 of the frame 71.

[0011] FIG. 2 is a diagram illustrating a portion of a cross section perpendicular to the axial direction of the rotating electric machine 100 according to the first embodiment. This diagram illustrates only a portion corresponding to approximately one-quarter of the circumference of the annular rotating electric machine 100. As shown in FIG. 2 , the stator 50 includes a stator core 51 formed by laminating electromagnetic steel sheets and three-phase coils 55 (U, V, and W) wound around the stator core 51 as armature windings. The stator core 51 includes an annular core back 51B, a plurality of teeth 51T extending radially inward X1 from the core back 51B, and a plurality of groove-shaped slots 51S formed by being surrounded by adjacent teeth 51T and core backs 51B. Coils 55 are housed in the slots 51S.

[0012] In the stator 50 of this embodiment, 96 slots 51S are formed at equal intervals in the circumferential direction C. If the central angle of an arc 61MS connecting the circumferential centers of circumferentially adjacent slots 51S with respect to the center point O of the rotor 60 is P1, then this central angle P1 is 360° / 96=3.75°. The coils 55 are connected by distributed winding, and the coils 55 in each slot 51S are connected in series or in parallel to each other.

[0013] The rotor 60 includes an annular rotor core 61 as a rotor core, and permanent magnets 62 (62IN, 62OUT) that constitute magnetic poles formed at set intervals in the circumferential direction of the rotor core 61. The permanent magnets 62 (62IN, 62OUT) are embedded in magnet insertion holes in the rotor core 61. Each magnetic pole has a two-layer structure in which a pair of permanent magnets 62IN as first permanent magnets is disposed on the radially inner side X1 and a pair of permanent magnets 62OUT as second permanent magnets is disposed on the radially outer side X2, with four permanent magnets 62 embedded per pole. The pair of permanent magnets 62IN, 62OUT are each disposed in a V-shape that widens toward the outer circumferential surface 61M of the rotor 60.

[0014] The rotor core 61 has flux barriers formed adjacent to both ends of the permanent magnets 62 to prevent leakage of magnetic flux from the permanent magnets 62. That is, the permanent magnets 62IN have flux barriers 63IN formed thereon as first flux barriers that communicate with both ends of the magnet insertion hole, and the permanent magnets 62OUT have flux barriers 63OUT formed thereon as second flux barriers that communicate with both ends of the magnet insertion hole. The flux barriers 63IN are formed to extend from both ends of the permanent magnets 62IN in the circumferential direction C toward the radially outward direction X2 at an extension angle θ3 set with respect to the permanent magnets 62IN.

[0015] In this embodiment, the rotor 60 has eight magnetic poles, and the number of slots q per pole per phase, obtained by dividing the total number of slots 96 by the number of phases 3 and the number of magnetic poles 8, is 96 / (8*3)=4. The larger this number of slots q per pole per phase, the more slots the stator 50 has. In this way, in the rotating electric machine 100 with a multi-slot structure, the number of slots 51S that face the outer peripheral surface 61M of the rotor core 61 between magnetic poles adjacent in the circumferential direction C increases.

[0016] 2 , between adjacent magnetic poles in the circumferential direction C, a region of the rotor core 61 where no flux barrier is formed near the outer peripheral surface 61M is defined as J1, and the arc constituting the outer peripheral surface 61M on the radially outer side X2 of this region J1 is defined as a first arc portion 61M1. If the central angle of this first arc portion 61M1 with respect to the center of rotation 0 of the rotor 60 is defined as θ1, in this embodiment, the central angle θ1 is configured to satisfy a first condition that θ1 = P1 × 2.1 or less. The vicinity of the outer peripheral surface 61M of the rotor core 61 refers to a region within a set range X1 radially inward from the outer peripheral surface 61M, and this set range is set according to the range in which magnetic flux short-circuits in the magnetic path from the teeth 51T → between the magnetic poles → teeth 51T, which will be described later.

[0017] Here, the effect of setting the central angle θ1 of the first arc portion 61M1 relative to the center of rotation 0 to P1×2.1 or less will be described using experimental results using a motor as a comparative rotating electric machine in which the value of θ1 was varied. FIG. 3 is a cross-sectional view perpendicular to the axial direction Y of a comparative rotating electric machine 100EX1 in which θ1 = P1 × 0.85. FIG. 4 is a cross-sectional view perpendicular to the axial direction Y of a comparative rotating electric machine 100EX2 in which θ1 = P1 × 2.08. FIG. 5 is a cross-sectional view perpendicular to the axial direction Y of a comparative rotating electric machine 100EX3 in which θ1 = P1 × 2.32. FIG. 6 is a graph showing the iron loss characteristics of a rotating electric machine when the central angle θ1 is varied. FIG. 7 is a diagram explaining the principle of increased iron loss in a rotating electric machine.

[0018] For motors for electric vehicles as rotating electric machines, efficiency in the medium speed and low load ranges when driving in urban areas is important, so electromagnetic field analysis was performed under conditions of low current and current phase of 90° using each of the rotating electric machines 100EX1, EX2, and EX3, and rotating electric machines having central angle θ1 values ​​other than these rotating electric machines 100EX1, EX2, and EX3. Note that in Figure 6, iron loss is normalized under the condition of θ1 = P1 × 2.08.

[0019] 6 shows that the inflection point where the change in iron loss with respect to the central angle θ1 abruptly changes is at θ1 = P1 × 2.08. This is because, as the number of slots 51S of the stator 50 facing the first arc portion 61M1 that defines the central angle θ1 increases, the amount of magnetic flux that short-circuits in the magnetic path from the teeth 51T to the inter-pole space and back to the teeth 51T increases through the region where no flux barrier is formed near the outer circumferential surface 61M of the rotor core 61, as shown by the arrow in FIG. 7. This increases the magnetic flux density in the teeth 51T, resulting in an increase in stator iron loss. Therefore, if the central angle θ1 that defines the first arc portion 61M1 is configured to satisfy the first condition of being set to 2.1 times or less than P1, stator iron loss can be reduced, enabling the rotating electric machine to have a high efficiency.

[0020] Here, even if the central angle θ1 is the same for a rotating electric machine with q=2 slots per pole per phase and a rotating electric machine with q=4 slots per pole per phase, the number of slots 51S facing the first arc portion 61M1 is twice as large as that for the rotating electric machine with q=2 slots. While increasing the number of slots suppresses fluctuations in the magnetic flux in the air gap between the stator and rotor and reduces torque ripple and cogging torque, increasing the number of slots facing the first arc portion 61M1 increases iron loss. In particular, if a rotor designed for a stator with q=2 to 3 slots per pole per phase, which is common in motors for electric vehicles, is applied to a stator with q=4 or more slots per pole per phase without changing the configuration, there is a high possibility of increasing iron loss due to the principle described above. In the rotating electric machine of this embodiment, even with a multi-slot configuration, the central angle θ1 is designed to ensure the first condition as described above. Therefore, both the quieter operation due to reduced torque ripple and the higher efficiency due to reduced stator iron loss can be achieved.

[0021] Furthermore, the rotating electric machine may have the following configuration. Fig. 8 is a diagram showing a portion of a cross section perpendicular to the axial direction of rotating electric machine 100A according to embodiment 1, and shows only a portion corresponding to approximately one-quarter of the circumference of annular rotating electric machine 100A. In each magnetic pole, a region of rotor core 61 between flux barrier 63IN and flux barrier 63OUT where no flux barrier is formed near outer peripheral surface 61M is defined as J2, and the arc that constitutes outer peripheral surface 61M on the radially outer side X2 of this region J2 is defined as second arc portion 61M2.

[0022] The vicinity of the outer peripheral surface 61M of the rotor core 61 refers to a region within a set range X1 radially inward from the outer peripheral surface 61M, and this set range is set according to the range in which magnetic flux short-circuits in the magnetic path between the magnet layers → the stator 50 → between the magnetic poles, which will be described later. If the central angle of this second arc portion 61M2 with respect to the center of rotation 0 is θ2, in this embodiment, the central angle θ2 is configured to satisfy the first condition of θ2 = P1 × 1.65 or less.

[0023] Here, the effect of setting the central angle θ2 of the second arc portion 61M2 relative to the center of rotation 0 to P1×1.65 or less will be described using experimental results using a motor as a comparative rotating electric machine with various values ​​of θ2. FIG. 9 is a cross-sectional view perpendicular to the axial direction Y of a comparative rotating electric machine 100EX4 when θ2 = P1 × 0.75. FIG. 10 is a cross-sectional view perpendicular to the axial direction Y of a comparative rotating electric machine 100EX5 when θ2 = P1 × 1.62. FIG. 11 is a cross-sectional view perpendicular to the axial direction Y of a comparative rotating electric machine 100EX6 when θ2 = P1 × 2.32. FIG. 12 is a graph showing the iron loss characteristics of a rotating electric machine when θ2 is varied. FIG. 13 is a diagram explaining the principle of increased iron loss in a rotating electric machine.

[0024] As in the case where θ1 was varied, electromagnetic field analysis was performed using the rotating electric machines 100EX4, EX5, and EX6 under the conditions of low current and a current phase of 90°. The analysis was performed by varying θ2 while maintaining the first condition of θ1 being equal to or less than P1 × 2.1. Note that in Figure 12, iron loss was normalized under the condition of θ2 = P1 × 1.62.

[0025] Figure 12 shows that the motor's iron loss decreases sharply with increasing central angle θ2 when the central angle θ2 is equal to or less than P1 × 1.65. This is because, as the number of slots 51S of the stator 50 facing the second arc portion 61M2 that defines the central angle θ2 increases, the amount of magnetic flux short-circuiting between the magnet layers, the stator 50, and the magnetic poles increases, as shown by the arrows in Figure 13. This increases the magnetic flux density in the teeth 51T, leading to increased stator iron loss. Therefore, the first condition, that the central angle θ2 that defines the second arc portion 61M2 be set to 1.65 times P1 or less, is met. Increasing the magnetic resistance of the path in this way disperses the magnetic flux that would otherwise concentrate on a specific stator tooth, reduces localized concentration of magnetic flux density in the teeth, reduces stator iron loss, and enables higher efficiency in rotating electrical machines.

[0026] The iron loss characteristics when θ2 is changed have been described above. The torque characteristics when θ2 is changed will now be described. Fig. 14 is a graph showing the torque characteristics of a rotating electric machine when θ2 is changed while the first condition, that is, θ2 is equal to or less than P1 × 1.65, is satisfied. As described above, the magnetic resistance can be increased by reducing the central angle θ2, i.e., by shortening the length of the second arc portion 61M2. However, if the central angle θ2 is made too small, it will result in a decrease in torque, as shown in Fig. 14.

[0027] Therefore, by configuring the central angle θ2 to satisfy the first condition of θ1 = P1 × 1 or greater while being equal to or less than P1 × 1.65, it is possible to minimize torque reduction, i.e., to suppress torque reduction to 1% or less compared to a rotating electric machine configured as the standard θ2 = P1 × 1.62, while achieving high efficiency in the rotating electric machine.

[0028] The rotating electric machine may also be configured as described below. Fig. 15 is a diagram showing a portion of a cross section perpendicular to the axial direction of a rotating electric machine 100B according to the first embodiment. In the rotating electric machine 100 shown in Fig. 2 described above, each magnetic pole has a two-layer configuration including a pair of permanent magnets 62IN as first permanent magnets constituting a first layer and a pair of permanent magnets 62OUT as second permanent magnets constituting a second layer. In the rotating electric machine 100B shown in Fig. 15, the magnetic pole has a total of three-layer configuration including a pair of permanent magnets 62IN as first permanent magnets constituting a first layer and two more layers of pairs of permanent magnets 62OUT as second permanent magnets.

[0029] The effect of arranging each magnetic pole in multiple layers in the radial direction will be explained below. In a two-layer configuration in which the magnetic poles are arranged in two layers in the radial direction, it is possible to position the magnetic circuit in the rotor closer to the alignment with the stator's excitation magnetic flux. This allows for effective use of reluctance torque, resulting in improved torque. Furthermore, a two-layer configuration allows for a relatively small number of magnets to be used compared to other multi-layer configurations that can effectively utilize reluctance torque, which means that the number of magnets that need to be inserted during rotor manufacturing can be reduced, leading to lower manufacturing costs.

[0030] However, with a two-layer magnetic pole configuration, the number of magnet layers used is small, which tends to result in a configuration with large θ1 or θ2. For example, if a rotor with eight two-layer magnetic poles designed for 24 slots (q = 1), 48 slots (q = 2), or 72 slots (q = 3), where q is less than 4, is used for a 96-slot configuration (q = 4), this tends to result in increased iron loss due to insufficient consideration of the P1 value of θ1 or θ2. In such a configuration, a rotating electric machine 100B such as that shown in FIG. 15 is effective. Increasing the number of magnetic pole layers from a two-layer configuration to a three-layer configuration increases the degree of freedom in the magnetic pole shape, allowing for more effective use of reluctance torque and improving torque.

[0031] The pair of permanent magnets constituting each layer of the magnetic poles is not limited to a V-shape expanding toward the outer circumferential surface of the rotor, and may be arranged in a flat plate or V-shape, etc., and the shape and number of magnet insertion holes, and the shape and number of permanent magnets are not important. For example, in a rotor having magnetic poles arranged in a flat plate, between magnetic poles each having only one permanent magnet as the first permanent magnet, the central angle θ1 of the first arc portion constituting the outer circumferential surface of the rotor core on the radial outside where no flux barrier is formed is configured to ensure the first condition.

[0032] Although the configuration shown has 8 poles and 96 slots, the above effects can be obtained even if the number of poles and slots is not limited to this. q is a number equal to or greater than 4 and is not limited to an integer. Furthermore, since the purpose of the flux barrier is to suppress leakage of magnetic flux, it may be made of a material with a lower relative permeability than the electromagnetic steel sheet, such as air or resin.

[0033] Furthermore, because high output is required for motors for electric vehicles, most stator cores are configured with an outer diameter of φ150 to φ300 mm due to the constraints of vehicle installation space and requirements for torque and power density. When designing a high-output motor with a diameter of φ150 mm or more, it is desirable to select a rotor with six or more poles, as explained below.

[0034] The optimal split ratio (rotor core outer diameter / stator core outer diameter) for a high-torque, high-output motor design must be approximately 60 to 80%. The smaller the number of poles, the larger the pole pitch (the central angle relative to the arc length of the rotor core per pole), increasing the amount of magnetic flux flowing through the stator core back. To avoid magnetic saturation in the core back, the core back must be designed to be thicker, but reducing the number of poles increases the proportion of the motor's radial length that is taken up by the core back thickness, making it impossible to ensure a split ratio of 60 to 80%. Therefore, for motors for electric vehicles, designs with fewer than four poles should be avoided; a configuration of six or more poles is preferable.

[0035] In adjusting θ1 to ensure the first condition, for example, the extension angle θ3 of the flux barrier 63IN shown in Figure 2 may be adjusted, or the end of the flux barrier 63IN on the radially outer side X2 may be formed to extend along the outer peripheral surface 61M of the rotor core 61, as shown in Figure 2.

[0036] The rotating electric machine of this embodiment configured as described above includes: a stator having a plurality of teeth protruding radially inward from an annular yoke portion, with an armature winding wound in a plurality of slots formed between the teeth, and a rotor having a rotor core on which a plurality of magnetic poles made of permanent magnets and flux barriers are formed, wherein the number of slots per pole per phase, obtained by dividing the total number of slots by the number of phases and the number of magnetic poles of the rotor, is 4 or more and the armature winding is configured in a distributed winding manner, wherein first flux barriers are formed adjacent to both circumferential ends of first permanent magnets constituting each of the magnetic poles, and the central angle θ1 of a first arc portion constituting the radially outer outer peripheral surface of the rotor core on which no flux barrier is formed between circumferentially adjacent magnetic poles is configured so as to satisfy a first condition that θ1 = P1 × 2.1 or less, where P1 is the central angle of the arc connecting the circumferential centers of circumferentially adjacent slots. This makes it possible to provide a highly efficient rotating electric machine even in a multi-slot structure with a large number of slots per pole per phase.

[0037] Furthermore, in the rotating electric machine of this embodiment configured as described above, the magnetic poles are configured in multiple layers by arranging second permanent magnets, each of which has a second flux barrier formed adjacent to both circumferential ends as the flux barrier, radially outward of the first permanent magnets, and in each of the magnetic poles, the central angle θ2 of a second arc portion constituting the outer peripheral surface of the rotor core on the radially outer side where the flux barrier is not formed between the first flux barrier and the second flux barrier, satisfies the first condition of θ2 = P1 × 1.65 or less. This increases the magnetic resistance between the first and second permanent magnets → stator → magnetic poles, and disperses the magnetic flux linking to the teeth, thereby alleviating local concentration of magnetic flux density and reducing stator iron loss.

[0038] In the rotating electric machine of this embodiment configured as described above, the central angle θ2 is configured to ensure the first condition of being equal to or greater than P1 × 1. This makes it possible to reduce stator iron loss and suppress a decrease in torque.

[0039] In the rotating electric machine of this embodiment configured as described above, the first flux barriers are formed to extend radially outward from both circumferential ends of the first permanent magnet at an extension angle θ3 set with respect to the first permanent magnet, and the extension angle θ3 is adjusted to ensure the first condition. Adjusting the extension angle θ3 in this manner makes it easy to adjust θ1 and θ2 to ensure the first condition.

[0040] Embodiment 2. Hereinafter, Embodiment 2 of the present application will be described with reference to the drawings, focusing on differences from Embodiment 1 described above. The same components as those in Embodiment 1 are designated by the same reference numerals, and description thereof will be omitted. FIG. 16 is a diagram showing a portion of a cross section perpendicular to the axial direction of a rotating electric machine 200 according to Embodiment 2, and only a portion corresponding to approximately one-quarter of the circumference of the annular rotating electric machine 200 is shown in this diagram. FIG. 17 is a partially enlarged cross section of the rotating electric machine 200 of FIG. 16, illustrating an example in which the shape of the end portion of the flux barrier 63IN on the radially outer side X2 is different. FIG. 18 is a diagram showing a portion of a cross section perpendicular to the axial direction of a rotating electric machine 200A according to Embodiment 2.

[0041] In the rotating electric machines 200 and 200A of this embodiment, a flux barrier 263M is provided as a third flux barrier that is configured independently without being connected to the flux barriers 63IN and 63OUT near the outer circumferential surface 61M of the rotor core 61 between each magnetic pole.

[0042] 16 , the first arc portion 61M1 constituting θ1 is defined as the arc obtained by subtracting the circumferential length of the flux barrier 263M from the arc length of the rotor core 61 between adjacent flux barriers 63IN between each magnetic pole. That is, the first arc portion 61M1 in the rotary electric machine 200 of this embodiment is the sum of the arcs 61M1A and 61M1B constituting the outer peripheral surface of the rotor core 61 on the radially outer side X2 where no flux barrier 263M is formed, between the flux barriers 63IN between magnetic poles adjacent in the circumferential direction C.

[0043] 18 , the flux barrier 263M serving as the third flux barrier may be formed between one side of the flux barrier 63OUT in the circumferential direction C and the other side of the flux barrier 63IN in the circumferential direction C at each magnetic pole. In this case, the second arc portion constituting θ2 is defined as the second arc portion 61M2 obtained by subtracting the circumferential length of the flux barrier 263M from the arc length of the outer circumferential surface 61M of the rotor core 61 between the flux barrier 63OUT and the flux barrier 63IN. That is, the second arc portion 61M2 in this embodiment is the sum of the arcs 61M2C and 61M2D constituting the outer circumferential surface of the rotor core 61 on the radially outer side X2 where the flux barrier 263M is not formed between the flux barrier 63OUT and the flux barrier 63IN.

[0044] In this way, by arranging the independently configured flux barriers 263M, it is possible to increase the number of parameters that change the rotor's permeance, magnetomotive force, etc., thereby expanding design flexibility. For example, torque ripple can be reduced by adjusting the position, shape, etc. of the flux barriers to cancel out fluctuations in the excitation magnetic flux of the stator 50. Furthermore, an extremely large flux barrier increases the stress on the bridge portion 261B (shown in FIG. 17 ) between the rotor's flux barrier and the outer circumferential surface 61M at high rotation speeds, which may reduce centrifugal force resistance. Even in such cases, by arranging the independently formed flux barriers 263M, the rib 261R (shown in FIG. 17 ) is formed between the flux barriers, thereby dispersing the stress on the bridge portion 261B to the rib 261R. This contributes to improving centrifugal force resistance.

[0045] In order to prevent deformation of the rotor core 61 due to centrifugal force, it is conceivable to increase the width of the bridge portions 261B in the radial direction X to alleviate stress. However, increasing the width of the bridge portions 261B leads to a decrease in torque due to an increase in leakage magnetic flux. Therefore, in order to achieve high torque while ensuring centrifugal force resistance, it is necessary to set the width of the bridge portions 261B in the radial direction X as narrow as possible, for example, to 2% or less of the rotor diameter. On the other hand, if the width of the bridge portions 261B is made too narrow, magnetic flux will easily flow into the stator core 51, leading to an increase in stator iron loss. Therefore, the width of the bridge portions 261B in the radial direction X may be set to 2% or less of the rotor diameter, and this value may be further adjusted.

[0046] Further modifications in which the position of the flux barrier 263M is adjusted will be described below. Fig. 19 is a diagram showing a portion of a cross section perpendicular to the axial direction of a rotating electric machine 200B according to the second embodiment. Fig. 20 is a diagram showing a portion of a cross section perpendicular to the axial direction of a rotating electric machine 200C according to the second embodiment. Fig. 21 is a diagram showing a portion of a cross section perpendicular to the axial direction of a rotating electric machine 200D according to the second embodiment.

[0047] As shown in FIG. 19, a configuration may be adopted in which flux barriers 263M are disposed both between adjacent flux barriers 63IN in the circumferential direction C and between the flux barriers 63OUT and 63IN at each magnetic pole.

[0048] 20 , in a more effective configuration, the flux barrier 263M may be configured so that its radially outermost portion X2 is positioned radially outwardly X2 of the flux barriers 63IN and 63OUT. If the distance between the flux barrier 263M and the outer peripheral surface 61M of the rotor core 61 is long, magnetic flux is more likely to short-circuit between the flux barrier 263M and the outer peripheral surface 61M, reducing its function as a flux barrier. Therefore, by configuring the flux barrier 263M to be closer to the outer peripheral surface 61M of the rotor core 61, as in the rotating electric machine 200C of FIG. 20 , the flux barrier function is improved and the iron loss reduction effect is increased.

[0049] 21, the flux barrier 263M may be disposed on the outer peripheral surface 61M side of the rotor core 61 so as to cut out the outer peripheral surface 61M on the radially outer side X2 of the rotor core 61. In this case, too, the effect of providing the flux barrier 263M described above can be similarly obtained.

[0050] Fig. 22 is a diagram showing the magnetomotive force distribution in a rotating electric machine configured without a flux barrier 263M. Fig. 23 is a diagram showing the magnetomotive force distribution in a rotating electric machine configured with a flux barrier 263M. As shown in Figs. 22 and 23, by providing the flux barrier 263M and adjusting its position, it is possible to adjust the magnetomotive force distribution of the rotor 60 to approach a sinusoidal wave, thereby reducing torque ripple.

[0051] The rotating electric machine of this embodiment configured as described above comprises a third flux barrier as the flux barrier formed independently from the first flux barrier and the second flux barrier, and the third flux barrier is disposed at least either between one circumferential side of the second flux barrier and the other circumferential side of the first flux barrier at each of the magnetic poles, or between circumferentially adjacent first flux barriers between each of the circumferentially adjacent magnetic poles, and the first arc portion is the sum of arcs that form the radially outer outer peripheral surface of the rotor core where the third flux barrier is not formed between the circumferentially adjacent magnetic poles, and the second arc portion is the sum of arcs that form the radially outer outer peripheral surface of the rotor core where the third flux barrier is not formed between the first flux barrier and the second flux barrier at each of the magnetic poles. In this way, by providing a third flux barrier and configuring the central angle θ2 to ensure the first condition, torque ripple can be reduced and centrifugal force resistance can be improved, while local concentration of magnetic flux density in the teeth can be alleviated, reducing stator iron loss and making it possible to increase the efficiency of the rotating electric machine.

[0052] In the rotating electric machine of this embodiment configured as described above, the position of the third flux barrier is adjusted so that the magnetomotive force distribution of the rotor approaches a sinusoidal wave, thereby achieving a quieter rotating electric machine with reduced torque ripple.

[0053] Although various exemplary embodiments and examples are described in this application, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless modifications not illustrated are contemplated within the scope of the technology disclosed in this application. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment.

[0054] 50 Stator, 51 Stator core, 51B Yoke portion, 51T Teeth, 51S Slot, 61 Rotor core (rotor iron core), 62IN Permanent magnet (first permanent magnet), 62OUT Permanent magnet (second permanent magnet), 63IN Flux barrier (first flux barrier), 63OUT Flux barrier (second flux barrier), 263M Third flux barrier (flux barrier), 55 Coil (armature winding), 100, 100A, 100B, 200A, 200B, 200C, 200D Rotating electric machine.

Claims

1. a stator having a plurality of teeth protruding radially inward from an annular yoke portion and an armature winding wound in a plurality of slots formed between the teeth; and a rotor having a rotor core on which a plurality of magnetic poles and flux barriers formed by permanent magnets are formed, In a rotating electric machine in which the number of slots per pole per phase obtained by dividing the total number of slots by the number of phases and the number of magnetic poles of the rotor is 4 or more, and the armature winding is configured as a distributed winding, a first flux barrier is formed adjacent to each of both circumferential ends of the first permanent magnet constituting each of the magnetic poles; A central angle θ1 of a first arc portion constituting a radially outer outer peripheral surface of the rotor core where the flux barrier is not formed between the magnetic poles adjacent in the circumferential direction is The first condition is satisfied so that θ1=P1×2.1 or less. Rotating electric motor. Here, P1 is the central angle of an arc connecting the circumferential centers of the slots adjacent in the circumferential direction.

2. The magnetic poles are configured in a plurality of layers by disposing second permanent magnets radially outwardly of the first permanent magnets, the second permanent magnets being adjacent to both ends in a circumferential direction and having second flux barriers formed thereon as the flux barriers, In each of the magnetic poles, a central angle θ2 of a second arc portion constituting a radially outer outer peripheral surface of the rotor core where the flux barrier is not formed between the first flux barrier and the second flux barrier is The first condition is ensured so that θ2=P1×1.65 or less. The rotating electric machine according to claim 1 .

3. The central angle θ2 is The first condition is ensured to be equal to or greater than P1×1. The rotating electric machine according to claim 2 .

4. the first flux barrier is formed so as to extend radially outward from both circumferential ends of the first permanent magnet at an extension angle θ3 set with respect to the first permanent magnet, The extension angle θ3 is adjusted so as to ensure the first condition. The rotating electric machine according to claim 2 .

5. the first flux barrier is formed so as to extend radially outward from both circumferential ends of the first permanent magnet at an extension angle θ3 set with respect to the first permanent magnet, The extension angle θ3 is adjusted so as to ensure the first condition. The rotating electric machine according to claim 3 .

6. a third flux barrier formed independently of the first flux barrier and the second flux barrier; The third flux barrier comprises: Between one side of the second flux barrier in the circumferential direction and the other side of the first flux barrier in the circumferential direction at each of the magnetic poles, or Between the magnetic poles adjacent in the circumferential direction, between the first flux barriers adjacent in the circumferential direction, and The first arc portion is is the sum of arcs constituting the outer peripheral surface of the rotor core on the radially outer side where the third flux barrier is not formed between the magnetic poles adjacent in the circumferential direction, The second arc portion is a sum of arcs constituting a radially outer peripheral surface of the rotor core where the third flux barrier is not formed between the first flux barrier and the second flux barrier in each of the magnetic poles, The rotating electric machine according to any one of claims 2 to 5.

7. The third flux barrier comprises: The arrangement position of the rotor is adjusted so that the magnetomotive force distribution of the rotor approaches a sine wave. The rotating electric machine according to claim 6.

8. a radially outer portion of the third flux barrier is disposed radially outward of radially outer portions of the first flux barrier and the second flux barrier; The rotating electric machine according to claim 6.

9. a radially outer portion of the third flux barrier is disposed radially outward of radially outer portions of the first flux barrier and the second flux barrier; The rotating electric machine according to claim 7.

10. the third flux barrier is disposed on an outer circumferential surface side of the rotor core so as to cut out a radially outer side of the rotor core; The rotating electric machine according to claim 6.

11. the third flux barrier is disposed on an outer circumferential surface side of the rotor core so as to cut out a radially outer side of the rotor core; The rotating electric machine according to claim 7.

12. the third flux barrier is disposed on an outer circumferential surface side of the rotor core so as to cut out a radially outer side of the rotor core; The rotating electric machine according to claim 8.

13. the third flux barrier is disposed on an outer circumferential surface side of the rotor core so as to cut out a radially outer side of the rotor core; The rotating electric machine according to claim 9.

14. The magnetic pole having a multi-layer structure has a two-layer structure including a first flux barrier constituting a first layer and the second flux barrier constituting a second layer. The rotating electric machine according to any one of claims 2 to 5.

15. The magnetic pole having a plurality of layers is configured of three or more layers, including a first flux barrier constituting a first layer and a plurality of second flux barriers constituting second and subsequent layers. The rotating electric machine according to any one of claims 2 to 5.

16. At least one of the bridge portions formed between the first flux barrier and the outer circumferential surface of the rotor core and the second flux barrier is formed so that the radial width of the bridge portion is 2% or less of the diameter of the rotor. The rotating electric machine according to any one of claims 2 to 5.

17. The first permanent magnet and the second permanent magnet are configured to have a pair of magnets arranged in a V shape expanding toward the outer circumferential surface side of the rotor. The rotating electric machine according to any one of claims 2 to 5.

18. The number of magnetic poles is six or more. The rotating electric machine according to any one of claims 1 to 5.