Design method for rotor core, rotor, rotating electric machine, and rotor core

Abstract

A rotor core (31) is formed with a plurality of third flux barriers (37) provided corresponding to at least one magnetic pole (33) among a plurality of magnetic poles (33). In the rotor core (31), a first insertion hole (34f) is formed into which a permanent magnet (32) (front magnet (32f)) is inserted, said permanent magnet (32) being disposed toward the front F side among the respective magnetic poles (33). The third flux barriers (37) are each provided at a position facing a first side surface on the radially outer side of the rotor core (31) among the side surfaces facing the short direction of the first insertion hole (34f) and are connected to the first side surface.

Description

Technical Field

[0001] The present invention relates to a rotor core, a rotor, a rotating electric machine, and a method for designing a rotor core. This application claims priority based on Japanese Patent Application No. 2023-060098 filed in Japan on April 3, 2023, and incorporates its contents herein.

Background Art

[0002] Conventionally, for example, a rotating electric machine described in Patent Document 1 below is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In this type of interior permanent magnet synchronous motor (IPMSM), the practical application of a technology capable of suppressing torque ripple (torque ripple) is required.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to reduce torque ripple.

Means for Solving the Problems

[0006] <1>According to one aspect of the present invention Rotating electric machine is A rotating electric machine comprising an annular stator and a rotor disposed within the stator, wherein the rotor comprises a rotor core and permanent magnets embedded in the rotor core and constituting magnetic poles, and a plurality of sets of permanent magnets arranged in the circumferential direction of the rotor core, and the rotor core is a rotor core used in an embedded magnet type motor, in which a plurality of sets of permanent magnets constituting magnetic poles are arranged in the circumferential direction of the rotor core Re, front the rotor core has a plurality of insertion holes formed therethrough in the axial direction of the rotor core and into which the permanent magnets are inserted, and the rotor core is provided corresponding to at least one of the plurality of magnetic poles TafuA Lux barrier is formed, and the insertion hole includes a first insertion hole into which the permanent magnets, which are arranged towards the front of the rotation of each of the magnetic poles, are inserted. Note The Lux barrier is provided at a position on the side surface facing the short direction in the first insertion hole, opposite to the first side surface on the radially outer side of the rotor core, and is connected to the first side surface. The flux barrier is a rotating electric machine in which the circumferential barrier opening angle θw of the rotor at the outer peripheral surface located radially outside the rotor satisfies the following equations (1) and (2). When (2 / 5)θs < θm < (3 / 4)θs, 0<θw<(22 / 7)θm-(44 / 35)θs…(1) When (3 / 4)θs ≤ θm < (9 / 10)θs, 0<θw<-(22 / 3)θm+(33 / 5)θs…(2) θs = 2π / Nslot ... (3) Here, Nslot in equation (3) above means the number of slots in the stator. θm represents the barrier center angle formed between the circumferential center position on the outer peripheral surface and the radially outer end of the flux barrier extending forward from the first insertion hole. .

[0007] <2> According to one aspect of the present invention Rotating electric machine teeth, A rotating electric machine comprising an annular stator and a rotor disposed within the stator, wherein the rotor comprises a rotor core and permanent magnets embedded in the rotor core and constituting magnetic poles, and a plurality of sets of permanent magnets arranged in the circumferential direction of the rotor core, and the rotor core is A rotor core used in an embedded magnet type motor, wherein multiple sets of permanent magnets constituting magnetic poles are arranged in the circumferential direction of the rotor core. ,before The rotor core has a plurality of insertion holes formed therein that penetrate the rotor core in the axial direction and into which the permanent magnets are inserted, and the rotor core is provided corresponding to at least one of the plurality of magnetic poles Tafu A Lux barrier is formed, and the insertion hole includes a first insertion hole into which the permanent magnets, which are arranged towards the front of the rotation of each of the magnetic poles, are inserted. Note The Lux barrier is located in the first insertion hole at a position on the side facing the short direction of the first insertion hole, opposite to the first side facing the radially outer side of the rotor core. ,before The magnetic flux generated from the permanent magnet inserted into the first insertion hole is divided in the circumferential direction. A rotating electric machine provided in close proximity to the rotor, wherein the flux barrier has an outer peripheral surface located radially outside the rotor, and the circumferential barrier opening angle θw of the rotor satisfies the following equations (1) and (2). When (2 / 5)θs < θm < (3 / 4)θs, 0<θw<(22 / 7)θm-(44 / 35)θs…(1) When (3 / 4)θs ≤ θm < (9 / 10)θs, 0<θw<-(22 / 3)θm+(33 / 5)θs…(2) θs = 2π / Nslot ... (3) Here, Nslot in equation (3) above means the number of slots in the stator. θm represents the barrier center angle formed between the circumferential center position on the outer peripheral surface and the radially outer end of the flux barrier extending forward from the first insertion hole. 。

[0008] <3>In the case of the above <1> or <2>, Rotating electric machine then, the Note rack barrier may have a portion that increases in the circumferential direction of the rotor core as it goes toward the outer side in the radial direction.

[0009] <4>In the case of any one aspect according to the above <1> to <3>, Rotating electric machine then, the Note rack barrier may block the magnetic flux that goes from the rearward side of rotation to the forward side of rotation at the magnetic pole among the magnetic fluxes generated from the permanent magnet inserted into the first insertion hole.

[0010] <5>In the case of any one aspect according to the above <1> to <4>, Rotating electric machine then, among the rotor core, Note a bridge may be provided in a portion located on the outer side in the radial direction with respect to the rack barrier.

[0014] < 6 >The design method according to one aspect of the present invention Rotating electric machine is the design method described in any one aspect from <1> to <5>, and includes a step of designing the position and shape of the Rotating electric machine rack barrier based on the magnetic flux near the forward side of rotation at the magnetic pole. Note

[0015] <<0000​​​​​​​​​​​​​​According to the present invention, torque pulsation is reduced. [Brief explanation of the drawing]

[0017] [Figure 1] This is a diagram showing a rotating electric machine according to one embodiment of the present invention, and is a plan view including a partial cross-section. [Figure 2] Figure 1 is an enlarged plan view of the stator and rotor included in the rotating electric machine shown. [Figure 3] Figure 1 is an enlarged plan view of the rotor included in the rotating electric machine shown. [Figure 4] This figure shows a partial cross-section of a rotating electric machine according to one embodiment of the present invention, and is an enlarged plan view of a rotor included in the rotating electric machine. [Figure 5] This is an enlarged plan view schematically showing a part of the rotor shown in Figure 3. [Figure 6] This is a plan view showing a rotating electric machine as an example. [Figure 7] This graph shows the results of comparing the torque ripple of the rotating electric machine in the embodiment and the rotating electric machine in the comparative example, as determined by electromagnetic field analysis. [Figure 8] This is a plan view showing a rotor in an embodiment of a rotating electric machine that can optimally reduce torque pulsation. [Figure 9] This is a plan view showing the rotor with maximized average torque in the comparative example rotating electric machine. [Figure 10] This graph shows the relationship between electrical angle and torque for the rotating electric machine of the embodiment and the rotating electric machine of the comparative example. [Figure 11] This is a plan view showing the magnetic flux density vector when the rotor of the rotating electric machine of the embodiment is positioned at the electrical angle where the torque waveform of the rotating electric machine of the comparative example is minimized. [Figure 12] This is a plan view showing the magnetic flux density vector when the rotor is positioned at the electrical angle where the torque waveform is minimized in the comparative example rotating electric machine. [Figure 13] This is a plan view showing the magnetic flux density vector when the rotor of the comparative example's rotating electric machine is positioned at the electrical angle where the torque waveform of the embodiment's rotating electric machine is maximized. [Figure 14]This is a plan view showing the magnetic flux density vector when the rotor is positioned at the electrical angle where the torque waveform is maximized in the comparative example rotating electric machine. [Modes for carrying out the invention]

[0018] The following describes a rotor core, rotor, rotating electric machine, and design method for the rotor core according to one embodiment of the present invention, with reference to Figures 1 to 14. The rotating electric machine is an electric motor, specifically an AC motor, more specifically a synchronous motor, and even more specifically a permanent magnet field motor. This type of electric motor is suitably used, for example, in electric vehicles.

[0019] As shown in Figures 1 and 2, the rotating electric machine 10 comprises a stator 20, a rotor 30, a case 50, and a rotating shaft 60. The stator 20 and rotor 30 are housed in the case 50. The stator 20 is fixed to the case 50. The rotating electric machine 10 is an inner rotor type in which the rotor 30 is located inside the stator 20.

[0020] In this embodiment, the rotating electric machine 10 is an 8-pole, 24-slot three-phase AC motor. However, the number of poles, slots, and phases can be changed as appropriate. Furthermore, in the rotating electric machine 10, the axes of the stator 20 and the rotor 30 lie on a common axis. Hereafter, this common axis will be referred to as the central axis O (the central axis of the rotor 30). The direction in the direction of the central axis O (the axial direction of the rotor core 31, which will be described later) will be called the axial direction, the direction perpendicular to the central axis O (the radial direction of the rotor core 31, which will be described later) will be called the radial direction, and the direction that revolves around the central axis O (the circumferential direction of the rotor core 31, which will be described later) will be called the circumferential direction.

[0021] The stator 20 comprises a stator core 21 and windings (not shown). The stator core 21 comprises a cylindrical core back 22 (yoke) and a plurality of teeth 23.

[0022] The core back 22 is formed in an annular (ring-shaped) form when viewed from the axial direction of the rotating electric machine 10 in a plan view. Multiple teeth 23 project radially inward from the core back 22 (radially toward the central axis O of the core back 22). The multiple teeth 23 are arranged at equal intervals in the circumferential direction. In this embodiment, 24 teeth 23 are provided at 15-degree intervals around the central axis O. The multiple teeth 23 are formed to be of similar shape and size to each other. The space between adjacent teeth 23 in the circumferential direction is a slot 24. The winding is wound around the teeth 23. The winding may be a concentrated winding or a distributed winding.

[0023] As shown in Figure 3, the rotor 30 is positioned radially inward relative to the stator 20 (stator core 21). The rotor 30 comprises a rotor core 31 and a plurality of permanent magnets 32. The rotor core 31 is formed in a cylindrical shape and is arranged coaxially with the stator 20. The rotating shaft 60 is located inside the rotor core 31. The rotating shaft 60 is fixed to the rotor core 31 so as to rotate together with the rotor core 31. Multiple permanent magnets 32 are fixed to the rotor core 31. The rotor core 31 is provided with multiple magnetic poles 33. In this embodiment, two permanent magnets 32 form one magnetic pole 33. Multiple sets of permanent magnets 32 that make up multiple magnetic poles 33 are arranged at equal intervals in the circumferential direction. In this embodiment, eight sets (16 in total) of permanent magnets 32 are provided at 45-degree intervals around the central axis O.

[0024] The rotating electric machine 10 is an embedded permanent magnet synchronous motor (IPMSM). The rotor core 31 has a plurality of insertion holes 34 that penetrate the rotor core 31 in the axial direction. The plurality of insertion holes 34 are provided corresponding to a plurality of permanent magnets 32. Each permanent magnet 32 ​​is fixed to the rotor core 31 while inserted into the corresponding insertion hole 34. In other words, the insertion holes 34 form a space in which the permanent magnets 32 can be installed. In the embodiment shown in Figure 3, the permanent magnets 32 have a rectangular shape with a longitudinal direction, and the insertion holes 34 also have a shape that includes a portion that is a rectangular shape with a similar longitudinal direction. Fixing each permanent magnet 32 ​​to the rotor core 31 can be achieved, for example, by bonding the outer surface of the permanent magnet 32 ​​and the inner surface of the insertion hole 34 with an adhesive.

[0025] Furthermore, laminated cores can be used for the stator core 21 and rotor core 31. Laminated cores are formed by laminating multiple electromagnetic steel sheets. The laminated electromagnetic steel sheets are fixed to each other by methods such as crimping, bonding, or welding. Each electrical steel sheet forming the stator core 21 and rotor core 31 is formed, for example, by punching out a base electrical steel sheet. Known electrical steel sheets can be used as electrical steel sheets. The chemical composition of the electrical steel sheets is not particularly limited. In this embodiment, non-oriented electrical steel sheets are used as electrical steel sheets. For example, non-oriented electrical steel strips of JIS C 2552:2014 can be used as non-oriented electrical steel sheets. However, grain-oriented electrical steel sheets can also be used instead of non-oriented electrical steel sheets. For example, grain-oriented electrical steel strips of JIS C 2553:2012 can be used as grain-oriented electrical steel sheets.

[0026] To improve the processability of electrical steel sheets and the iron loss of laminated cores, insulating coatings are applied to both sides of the electrical steel sheets. The insulating coatings can be made from materials such as (1) inorganic compounds, (2) organic resins, or (3) mixtures of inorganic compounds and organic resins. Examples of inorganic compounds include (1) composites of dichromate and boric acid, and (2) composites of phosphate and silica. Examples of organic resins include epoxy resins, acrylic resins, acrylic styrene resins, polyester resins, silicone resins, and fluororesins.

[0027] The following describes the details of the rotor 30. As shown in Figure 3, the permanent magnets 32 are embedded in the rotor core 31 as described above, and two of them form a pair to constitute one magnetic pole 33. Multiple pairs (eight pairs in the illustrated example) of permanent magnets 32 are arranged in the circumferential direction on the rotor core 31. In the illustrated example, the permanent magnets 32 are rectangular in shape. In plan view, the permanent magnets 32 are rectangular.

[0028] The pair of permanent magnets 32 are arranged in a V-shape that is convex radially inward in the plan view. The pair of permanent magnets 32 are arranged symmetrically with respect to the d-axis Ld in the plan view. The d-axis Ld passes through the central axis O and the center of each magnetic pole 33 in the circumferential direction in the plan view. Similarly, the insertion holes 34 in which the pair of permanent magnets 32 are placed are arranged approximately symmetrically with respect to the d-axis Ld.

[0029] In the plan view, the insertion hole 34 is larger than the permanent magnet 32 ​​on both the q-axis Lq side and the d-axis Ld side. In the plan view, the q-axis Lq passes between the central axis O and the two adjacent magnetic poles 33 in the circumferential direction. In the plan view, the q-axis Lq passes through the circumferential center between the two magnetic poles 33. The q-axis Lq and the d-axis Ld are magnetically and electrically orthogonal. The portions of the insertion hole 34 located on the q-axis Lq side and the d-axis Ld side, respectively, relative to the permanent magnet 32, are flux barriers 35 and 36. In other words, flux barriers 35 and 36 are provided at both ends of the permanent magnet 32 ​​on the q-axis Lq side and the d-axis Ld side. The flux barriers 35 and 36 are magnetic gaps that penetrate the rotor core 31 in the axial direction. Flux barriers 35 and 36 reduce the magnetic flux from the permanent magnets 32 that recirculate within the rotor 30 (hereinafter also referred to as recirculating flux) or change the inflow path of the magnetic flux from the permanent magnets 32 to the stator 20. As a result, the magnetic flux from the permanent magnets 32 (hereinafter simply referred to as magnetic flux) is effectively transmitted to the stator 20, resulting in the output of high torque. It can also be said that flux barriers 35 and 36 guide the magnetic flux to the stator 20.

[0030] The rotor 30 includes a first flux barrier 35 and a second flux barrier 36 as flux barriers 35 and 36. The first flux barrier 35 and the second flux barrier 36 sandwich the permanent magnet 32 ​​from both ends in its longitudinal direction. This makes it easier for the magnetic flux of the magnet to be effectively transmitted to the stator 20. The first flux barrier 35 is located on the q-axis Lq side with respect to each permanent magnet 32. The first flux barrier 35 is located on both sides of the pair of permanent magnets 32 in the circumferential direction (direction of rotation). The second flux barrier 36 is located on the d-axis Ld side with respect to each permanent magnet 32. The second flux barrier 36 is located in the center of the pair of permanent magnets 32 in the circumferential direction (direction of rotation).

[0031] Hereinafter, the forward direction (forward rotation) of the rotation direction (circumferential direction) of the rotating electric machine 10 will be simply referred to as forward F, and the backward direction of rotation will be simply referred to as backward R. In the case of a rotating electric machine 10 that can rotate in both directions around the central axis O, the above rotation direction refers to the rotation direction in which the rotating electric machine 10 mainly rotates. In the illustrated example, when viewed from the plane of the paper, counterclockwise rotation is referred to as forward F, and clockwise rotation is referred to as backward R.

[0032] Among the multiple insertion holes 34 are multiple first insertion holes 34f. Each of the multiple first insertion holes 34f is inserted into a pair of permanent magnets 32, with the permanent magnet 32 ​​positioned towards the front F of each magnetic pole 33. Each pair of permanent magnets 32 includes a front magnet 32f and a rear magnet 32r. The front magnet 32f is positioned in front F of the rear magnet 32r. The front magnet 32f is inserted into the first insertion hole 34f.

[0033] The rotor 30 further comprises a plurality of third flux barriers 37 and a plurality of bridges 38. The plurality of third flux barriers 37 are provided corresponding to each of the plurality of magnetic poles 33. In this embodiment, one third flux barrier 37 is provided for each magnetic pole 33. The third flux barriers 37 are provided for the front magnet 32f but not for the rear magnet 32r. The third flux barriers 37 are provided only for the front magnet 32f. The plurality of third flux barriers 37 are magnetic gaps that penetrate the rotor core 31 in the axial direction. The third flux barriers 37 are provided at positions facing the radially outer side surface (hereinafter also referred to as the first side surface 34f1) of the side surface facing the short side of the first insertion hole 34f. The third flux barriers 37 are formed to divide (split) the magnetic flux generated from the front magnet 32f in the circumferential direction. The third flux barrier 37 is connected to the radially outer side of the first insertion hole 34f. In other words, the third flux barrier 37 is connected to the radially outer side of the first insertion hole 34f. That is, the third flux barrier 37 is connected to the first side surface 34f1. In the illustrated example, the third flux barrier 37 is connected to a portion of the first side surface 34f1 in a plan view. On the other hand, the third flux barrier 37 is connected along the entire length of the first side surface 34f1 in the axial direction. However, the third flux barrier 37 may be slightly separated from the radially outer side of the first insertion hole 34f, as shown in Figure 4. That is, the third flux barrier 37 may be close to the radially outer side of the first insertion hole 34f. In other words, the third flux barrier 37 may be close to the radially outer side of the first insertion hole 34f. The distance d (mm) between the third flux barrier 37 and the first insertion hole 34f is, for example, 0.03 mm or less. The distance d is the shortest distance between the third flux barrier 37 and the first insertion hole 34f. In this case, a portion remains between the third flux barrier 37 and the first insertion hole 34f that can become a flow path for magnetic flux. However, if the radial length (area) of this portion is sufficiently small, magnetic saturation will occur.Therefore, the magnetic flux generated from the forward magnet 32f is effectively divided circumferentially by the third flux barrier 37. For example, the third flux barrier 37 may be located radially outward from the first insertion hole 34f at a distance less than or equal to the radial length (width of the bridge 38) of the bridge 38. In this embodiment, an example is described in which the third flux barrier 37 is provided corresponding to all magnetic poles 33, but the third flux barrier 37 may be provided corresponding to at least one of the multiple magnetic poles 33. For example, there may be only one third flux barrier 37.

[0034] As shown in Figure 5, in a plan view from the axial direction, the portion of the third flux barrier 37 that is closer to the radially inward direction is tapered toward the radially inward direction (i.e., toward the first insertion hole 34f). The inner end portion 37a of the third flux barrier 37, which is the radially inward end, is connected to the first insertion hole 34f from the radially outward direction. The third flux barrier 37 is connected to the radially outer surface of the forward magnet 32f inserted into the first insertion hole 34f. The third flux barrier 37 is formed to increase in the circumferential direction of the rotor core 31 as it extends radially outward. The third flux barrier 37 blocks the magnetic flux (magnetic flux) generated when the rotor 30 rotates, specifically the magnetic flux toward the forward F direction at the magnetic pole 33.

[0035] The third flux barrier 37 has an outer peripheral surface 37b located radially outward. The outer peripheral surface 37b is located radially inward with respect to the outer peripheral surface 31a of the rotor core 31. The outer peripheral surface 37b is formed along the outer peripheral surface 31a. The outer peripheral surface 37b being along the outer peripheral surface 31a includes not only cases where the outer peripheral surface 37b is perfectly parallel to the outer peripheral surface 31a, but also cases where the outer peripheral surface 37b is substantially parallel to the outer peripheral surface 31a. The outer peripheral surface 37b being substantially parallel to the outer peripheral surface 31a means that the radial length of the bridge 38, described later, is substantially equal over the entire circumferential length of the bridge 38. The rotor core 31 includes a bridge 38 between the outer peripheral surface 31a and the outer peripheral surface 37b. That is, the bridge 38 is provided in each portion of the rotor core 31 that is radially outward with respect to the plurality of third flux barriers 37.

[0036] Multiple bridges 38 can prevent magnetic flux from passing through them by magnetic saturation. The bridges 38 only need to prevent magnetic flux from passing through them by magnetic saturation when the rotor 30 operates at a torque above a predetermined level, while the magnetic flux may pass through them when the rotor operates at a torque below that level. The circumferential length and radial width (radial length) of the bridges 38 are appropriately designed based on the rotational speed and shape of the rotating electric machine 10. The radial width of the bridges 38 will be explained in detail later.

[0037] In this embodiment, the third flux barrier 37 has an inner end portion 37a which is the portion that connects to the first insertion hole 34f (the closest portion), a widened portion 37g which is the portion that widens in the circumferential direction as it extends radially outward from the inner end portion 37a, and a connecting portion 37h which connects to a bridge 38 formed along the outer peripheral surface 37b. The inner end portion 37a is either point-shaped or linear. If the inner end portion 37a is large in the circumferential direction, the portion of the third flux barrier 37 that faces the front magnet 32f from the radially outer direction becomes larger, hindering the magnetic flux generated from the front magnet 32f and reducing the amount of magnetic flux generated. Therefore, it is preferable that the circumferential length of the inner end portion 37a be as short as possible (for example, 5% or less of the long side of the front magnet 32f). Furthermore, the widened portion 37g is triangular in shape, convex radially inward. Here, the widened portion 37g may be widened in a straight line or in a curved line. Furthermore, the connecting portion 37h is rectangular in shape and extends radially. However, the shape of the connecting portion 37h is not particularly limited, and it may be changed to another form in which a bridge 38 is formed between the outer peripheral surface 37b and the outer peripheral surface 31a. For example, if the radially outer circumferential length of the widening portion 37g is equal to the circumferential length of the outer peripheral surface 37b, the circumferential size of the connecting portion 37h may be the same over its entire radial length. Moreover, for example, if the radially outer circumferential length of the widening portion 37g is greater than the circumferential length of the outer peripheral surface 37b, the circumferential size of part or all of the connecting portion 37h may narrow circumferentially as it moves radially outward.

[0038] The details of the third flux barrier 37 are described below. The position and shape of the third flux barrier 37 are determined by the barrier center angle θm (radians), the barrier opening angle θw (radians), and the barrier connection position Xm. The barrier center angle θm refers to the angle formed circumferentially between the barrier center position 37c and the outer end 35a with respect to the central axis O. The barrier center position 37c refers to the circumferential center position on the outer peripheral surface 37b of the third flux barrier 37. The outer end 35a refers to the radially outer end in front of the first flux barrier 35 at F.

[0039] The barrier opening angle θw refers to the angle formed circumferentially by the front end 37d and the rear end 37e of the barrier with respect to the central axis O. The front end 37d of the barrier refers to the front F end on the outer peripheral side surface 37b of the third flux barrier 37. The rear end 37e of the barrier refers to the rear R end on the outer peripheral side surface 37b of the third flux barrier 37. The slot central angle θs refers to the central angle for each of the stator 20's 24 slots (see Figure 1). The barrier connection position Xm refers to the position in the circumferential (longitudinal) direction relative to the magnet length Mw on the outer surface of the front magnet 32f. As shown in Figure 4, when the third flux barrier 37 is slightly separated from the first insertion hole 34f, the barrier connection position Xm refers to the position on the outer surface of the front magnet 32f where the third flux barrier 37 and the first insertion hole 34f are closest, in the circumferential (longitudinal) direction relative to the magnet length Mw. Furthermore, the position where the distance d between the third flux barrier 37 and the first insertion hole 34f is measured is the barrier connection position Xm. These positions, lengths, and angles can be determined, for example, by photographing the rotor 30 in a plan view and analyzing the resulting image.

[0040] The position and shape of the third flux barrier 37 are determined to satisfy equations (1) to (4). That is, When (2 / 5)θs < θm < (3 / 4)θs, 0<θw<(22 / 7)θm-(44 / 35)θs…(1) When (3 / 4)θs ≤ θm < (9 / 10)θs, 0<θw<-(22 / 3)θm+(33 / 5)θs…(2) θs = 2π / Nslot ... (3) However, Nslot refers to the number of slots in stato 20. 0 ≤ Xm ≤ Mw …(4)

[0041] Furthermore, the radial length of the third flux barrier 37 is determined such that the magnetic flux density at the bridge 38 is greater than the saturation magnetic flux density of the soft magnetic material. For example, the radial width of the bridge 38 is 0.15 mm, and the magnetic flux density at the center of the bridge is 2.45 T. For example, if the saturation magnetic flux density of the rotor core 31 is 1.95 T, then the magnetic flux density at the center of the bridge, 2.45 T, exceeds the saturation magnetic flux density of the rotor core 31.

[0042] Here, the third flux barrier 37 is provided for the purpose of dividing the magnetic flux of the magnet. Therefore, the bridge 38 provided radially outside the third flux barrier 37 must be sufficiently narrow so that the magnetic flux of the magnet does not pass through it. On the other hand, from the standpoint of the mechanical strength of the rotor core 31, it is necessary to maintain a certain radial width in the bridge 38 in order to ensure the strength of the bridge 38. Therefore, it was considered sufficient to set the width of the bridge 38 such that the magnetic flux density exceeds the saturation magnetic flux density. The magnetic flux density of the bridge 38 can be determined, for example, by electromagnetic field analysis modeling the rotating electric machine 10.

[0043] Next, the reasons for setting the barrier central angle θm, barrier opening angle θw, and barrier connection position Xm based on equations (1) to (4) will be explained with reference to Figures 5 to 7. The rotating electric machine 10 of the embodiment shown in Figure 5 is equipped with a third flux barrier 37 on the rotor core 31. The comparative example rotating electric machine 100 shown in Figure 6 differs from the rotating electric machine 10 of the embodiment only in that it is not equipped with a third flux barrier 37 on the rotor core 101; the other configurations are the same as those of the rotating electric machine 10 of the embodiment. Figure 7 is a graph showing the results of comparing the torque ripple of the rotating electric machine 10 of the embodiment and the rotating electric machine 100 of the comparative example using electromagnetic field analysis.

[0044] Figure 7 shows (barrier opening angle θw) / (slot center angle θs)(%) on the vertical axis and (barrier center angle θm) / (slot center angle θs)(%) on the horizontal axis. Here, considering that even if the torque ripple is small, a small average torque will limit the applications, the rotating electric machine 10 of the embodiment and the rotating electric machine 100 of the comparative example were compared using the evaluation value (torque ripple) / (average torque). The smaller this evaluation value, the better the performance of the rotating electric machines 10 and 100. Graph G1 is a line (contour line) showing the conditions under which the evaluation value of the rotating electric machine 10 of the embodiment becomes equivalent to the evaluation value of the rotating electric machine 100 of the comparative example. In the inner region E1, which is located inside Graph G1, the evaluation value of the rotating electric machine 10 of the embodiment is smaller than (superior to) the evaluation value of the rotating electric machine 100 of the comparative example. Graph G2 is the line defined by equations (1) and (2) described later.

[0045] Graph G1 shows the results of the electromagnetic field analysis when the barrier connection position Xm of the inner end 37a of the third flux barrier 37 is positioned at the center of the magnet length Mw of the forward magnet 32f (i.e., Xm = (1 / 2)Mw). The reason for performing the electromagnetic field analysis for the case of Xm = (1 / 2)Mw in graph G1 is as follows. In other words, the effect of moving the barrier connection position Xm at the inner end 37a of the third flux barrier 37 is limited, and moving the barrier connection position Xm within the range of 0 to (maximum magnet length) in terms of magnet length Mw does not affect the effective range of torque pulsation reduction. For example, if the barrier connection position Xm is moved within the range of 0 ≤ Mw ≤ (maximum magnet length), the amount of magnetic flux contributing to the torque changes. The average torque increases or decreases in response to the change in magnetic flux, but the torque ripple also increases or decreases along with the increase or decrease in average torque. Therefore, the effects on the evaluation value cancel each other out, and the evaluation value for torque pulsation reduction does not change significantly.

[0046] The electromagnetic field analysis results showed that in the inner region E1 of graph G1, the torque ripple of the rotating electric machine 10 was smaller than that of the rotating electric machine 100, indicating a reduction in torque pulsation. In this region E2 of graph G1, which is outside of graph G2, the reduction in torque ripple of the rotating electric machine 10 is relatively small. That is, the torque ripple of the rotating electric machine 10 was appropriately reduced compared to the torque ripple of the rotating electric machine 100 in the inner region E3 of graph G2. As a result, the torque pulsation of the rotating electric machine 10 is appropriately reduced compared to that of the rotating electric machine 100 in the inner region E3 of graph G2. The inner region E3 of graph G2 corresponds to the range of barrier center angle θm and barrier opening angle θw shown in equation (1) and equation (2) above.

[0047] In the graph of Figure 7, 40% of the horizontal axis of (barrier central angle θm) / (slot central angle θs) corresponds to the position of (2 / 5)θs in equation (1). 75% of the horizontal axis of (barrier central angle θm) / (slot central angle θs) corresponds to the position of (3 / 4)θs in equations (1) and (2). 90% of the horizontal axis of (barrier central angle θm) / (slot central angle θs) corresponds to the position of (9 / 10)θs in equation (2). Furthermore, in the graph in Figure 7, the evaluation value was minimized when (barrier opening angle θw) / (slot center angle θs) on the vertical axis was 45.8% and (barrier center angle θm) / (slot center angle θs) on the horizontal axis was 75%, indicating optimal reduction of torque pulsation. Based on the results of this electromagnetic field analysis, the position and shape of the third flux barrier 37 were determined to satisfy equations (1) through (4).

[0048] Next, an example comparing the torque pulsation of the rotating electric machine 10 of the embodiment and the rotating electric machine 110 of the comparative example will be described based on Figures 8 to 10. Figure 8 shows a rotor 30 in the embodiment's rotating electric machine 10 that enables optimal reduction of torque pulsation. Figure 9 shows a rotor 112 in the comparative example's rotating electric machine 110 that maximizes average torque. Figure 10 is a graph showing the relationship between electrical angle and torque (torque waveform) for the embodiment's rotating electric machine 10 and the comparative example's rotating electric machine 110. In Figure 10, torque (Nm) is shown on the vertical axis and electrical angle (°) on the horizontal axis. The shapes of these rotors 30 and 112 were determined based on the analysis method described in Japanese Patent Application Publication No. 2021-114099.

[0049] In Figure 10, graph G3 shows the torque waveform of the rotating electric machine 10 of the embodiment. Graph G4 shows the torque waveform of the rotating electric machine 110 of the comparative example. By comparing the torque waveform of graph G3 with the torque waveform of graph G4, it can be confirmed that the torque pulsation in graph G3 is much smaller than that in graph G4. This confirms that the torque pulsation of the rotating electric machine 10 of the embodiment is much smaller than that of the rotating electric machine 110 of the comparative example.

[0050] Next, the magnetic flux density vectors in the rotating electric machine 10 of the embodiment shown in Figure 8 and the comparative example rotating electric machine 110 shown in Figure 9 will be explained based on Figures 11 to 14. First, in Figures 11 and 12, we will explain the magnetic flux density vector that occurs when the rotor 30 of the embodiment and the rotor 112 of the comparative example are positioned at the electrical angle θ1 where the torque waveform of the comparative example rotating electric machine 110, shown in graph G4 of Figure 10, is minimized.

[0051] Figure 11 shows the magnetic flux density vector when the rotor 30 is positioned at an electrical angle θ1 in the rotating electric machine 10 of the embodiment. As shown in Figure 11, in the rotating electric machine 10 of the embodiment, the magnetic flux coming from the rear R side portion 32fr of the front magnet 32f toward the front F side is blocked by the third flux barrier 37. The main paths of the circumferentially divided magnetic flux are toward different teeth 23. Therefore, it is possible to prevent this magnetic flux from being toward the teeth 23 located on the rear R side relative to the front magnet 32f. Thus, the negative torque generated by the magnetic flux can be reduced. As a result, the rotating electric machine 10 of the embodiment can suppress the decrease in torque at the electrical angle θ1.

[0052] Figure 12 shows the magnetic flux density vector when the rotor 112 is positioned at an electrical angle θ1 in the comparative example rotating electric machine 110. As shown in Figure 12, in the comparative example rotating electric machine 110, the magnetic flux coming from the rear R side portion 32fr of the front magnet 32f toward the front F side is directed toward the teeth 23 located on the rear R side relative to the front magnet 32f, as indicated by arrow A. The magnetic flux directed toward the teeth 23 generates a negative torque. As a result, the torque of the comparative example rotating electric machine 110 is minimized at the electrical angle θ1.

[0053] Next, in Figures 13 and 14, we will explain the magnetic flux density vector generated when the rotor 30 of the embodiment and the rotor 112 of the comparative example are positioned at the electrical angle θ2 where the torque waveform of the comparative example rotating electric machine 110, shown in graph G4 of Figure 10, is maximized. Figure 13 shows the magnetic flux density vector when the rotor 30 is positioned at an electrical angle θ2 in the rotating electric machine 10 of the embodiment. As shown in Figure 13, in the rotating electric machine 10 of the embodiment, the magnetic flux coming from the rear R side portion 32fr of the front magnet 32f to the front F side is blocked by the third flux barrier 37. Therefore, it is possible to prevent this magnetic flux from being directed towards the teeth 23 located on the front F side relative to the front magnet 32f, as indicated by arrow B. In other words, the third flux barrier 37 functions so that only the magnetic flux coming from the front F side portion 32ff of the front magnet 32f to the front F side is directed towards the teeth 23 located on the front F side relative to the front magnet 32f. Therefore, the positive torque generated by the magnetic flux can be reduced. As a result, the rotating electric machine 10 of the embodiment can suppress the torque at the electrical angle θ2 to a small amount.

[0054] Thus, as shown in graph G3 of Figure 10, the rotating electric machine 10 of this embodiment can suppress the decrease in torque at electrical angle θ1 and reduce the torque at electrical angle θ2. As a result, the rotating electric machine 10 of this embodiment can reduce the difference between the maximum torque and the minimum torque to almost zero, thereby reducing the torque pulsation of the rotating electric machine 10 as an IPMSM.

[0055] Figure 14 shows the magnetic flux density vector when the rotor 112 is positioned at an electrical angle θ2 in the comparative example rotating electric machine 110. As shown in Figure 14, the rotor core 31 of the comparative example rotating electric machine 110 is not provided with a third flux barrier for dividing the magnetic flux from the front magnet 32f as described above. Therefore, in the comparative example rotating electric machine 110, most of the magnetic flux from the front magnet 32f is directed from both the front F-side portion 32ff and the rear R-side portion 32fr of the front magnet 32f to the teeth 23 located on the front F side relative to the front magnet 32f, as indicated by arrow C. Thus, the magnetic flux coming from the entire surface of the front magnet 32f on the front F side contributes to the positive torque. For this reason, the torque of the comparative example rotating electric machine 110 is maximized at the electrical angle θ2.

[0056] Thus, as shown in graph G4 of Figure 10, the comparative example rotating electric machine 110 experiences a minimum torque at electrical angle θ1 and a maximum torque at electrical angle θ2. As a result, the comparative example rotating electric machine 110 exhibits a large difference between the maximum and minimum torques, leading to increased torque pulsation.

[0057] According to the design method for the rotor core 31, rotor 30, rotating electric machine 10, and rotor core 31 of the embodiment described above, the following effects can be obtained. Here, the inventors of the present invention have found that the torque pulsation of the IPMSM can be reduced by designing the position and shape of the third flux barrier 37 based on the magnetic flux towards the front F at the magnetic pole 33. Therefore, the design method for the rotor core 31 now includes a step for designing the position and shape of the third flux barrier 37. Specifically, in the design method for the rotor core 31, when the torque is maximum, the third flux barrier 37 blocks the magnetic flux near the front F of the magnetic pole 33 that generates the torque at the front F. Furthermore, when the torque is minimum, the third flux barrier 37 blocks the magnetic flux near the front F of the magnetic pole 33 that generates the torque at the rear R. Thus, in this design method, the position and shape of the third flux barrier 37 are designed based on the magnetic flux near the front F of the magnetic pole 33.

[0058] In the design process for this rotor core 31, the front magnet 32f of the magnetic pole 33 is inserted into the first insertion hole 34f, and a third flux barrier 37 is provided radially outside the rotor core 31 relative to the first insertion hole 34f. Furthermore, the third flux barrier 37 is connected radially outside the first insertion hole 34f. Thus, the magnetic flux that is about to exit the front magnet 32f and move forward F can be divided into a forward F side and a rear R side by the third flux barrier 37. As a result, when the torque is maximum, the magnetic flux on the rear R side of the third flux barrier 37 (the magnetic flux at part 32fr) is blocked from moving forward F, thereby blocking a portion of the magnetic flux that generates torque in the forward F direction. When the torque is minimum, the magnetic flux on the front F side of the third flux barrier 37 (the magnetic flux at part 32ff) is blocked from moving rear R, thereby blocking a portion of the magnetic flux that generates torque directed rear R. In this way, by suppressing the torque at the front F when the torque is at its maximum and suppressing the torque at the rear R when the torque is at its minimum, the torque pulsation of the rotating electric machine 10 can be reduced as an IPMSM.

[0059] Furthermore, the third flux barrier 37 has a portion that increases in the circumferential direction of the rotor core 31 as it extends radially outward. That is, the portion of the third flux barrier 37 closer to the first insertion hole 34f is tapered toward the first insertion hole 34f, and the inner end portion 37a is connected to the first insertion hole 34f from the radially outward direction. Therefore, the area in which the inner end portion 37a of the third flux barrier 37 connects to the first insertion hole 34f can be kept small. As a result, magnetic flux can be appropriately generated from the forward magnet 32f without being excessively obstructed by the third flux barrier 37.

[0060] Furthermore, by increasing the size of the third flux barrier 37 in the circumferential direction of the rotor core 31 as it extends radially outward, it is possible to prevent the magnetic flux emitted from the forward magnet 32f from passing through the third flux barrier 37. In this way, magnetic flux can be appropriately generated from the front magnet 32f, and furthermore, torque pulsation can be reduced more effectively by preventing the magnetic flux emitted from the front magnet 32f from passing through the front magnet 32f.

[0061] Furthermore, by connecting the third flux barrier 37 to the forward magnet 32f inserted into the first insertion hole 34f, it is possible to prevent the magnetic flux emitted from the forward magnet 32f from passing between the forward magnet 32f and the third flux barrier 37. This allows for a more effective reduction of torque pulsation.

[0062] In addition, the third flux barrier 37 blocks the magnetic flux generated from the front magnet 32f that travels from the rear R side towards the front F side. Therefore, when the torque is at its maximum, the magnetic flux that generates the torque at the front F is blocked, thereby suppressing the torque at the front F. Also, when the torque is at its minimum, the magnetic flux that generates the torque at the rear R is blocked, thereby suppressing the torque at the rear R. This reduces torque pulsation.

[0063] Furthermore, by ensuring that the magnetic flux density passing through the bridge 38 exceeds the saturation flux, it is possible to prevent the magnetic flux from passing through the bridge 38. This allows for a more effective reduction of torque pulsation.

[0064] Furthermore, the third flux barrier 37 is positioned on the front F side of the front magnet 32f when the barrier center angle θm is in the range of (2 / 5)θs < θm < (3 / 4)θs. In this case, the barrier opening angle θw of the third flux barrier 37 is set to 0 < θw < (22 / 7)θm - (44 / 35)θs. This allows the magnetic flux that generates torque at the front F to be blocked when the torque is maximum, and the magnetic flux that generates torque at the rear R to be blocked when the torque is minimum. Therefore, by suppressing the torque at the front F when the torque is maximum and suppressing the torque at the rear R when the torque is minimum, the torque pulsation of the rotating electric machine 10 can be reduced as an IPMSM.

[0065] Furthermore, the third flux barrier 37 is located on the rear R side of the front magnet 32f when the barrier center angle θm is in the range of (3 / 4)θs ≤ θm < (9 / 10)θs. In this case, the barrier opening angle θw of the third flux barrier 37 is set to 0 < θw < -(22 / 3)θm + (33 / 5)θs. This allows the magnetic flux that generates torque at the front F to be blocked when the torque is maximum, and the magnetic flux that generates torque at the rear R to be blocked when the torque is minimum. Therefore, by suppressing the torque at the front F when the torque is maximum and suppressing the torque at the rear R when the torque is minimum, the torque pulsation of the rotating electric machine 10 can be reduced as an IPMSM.

[0066] It should be noted that the technical scope of the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention.

[0067] The shape of the stator 20 is not limited to the form shown in the above embodiment. Specifically, the outer and inner diameters of the stator core 21, the stacking thickness, the number of slots, the circumferential and radial dimensional ratios of the teeth 23, and the radial dimensional ratio between the teeth 23 and the core back 22 can be arbitrarily designed according to the desired characteristics of the rotating electric machine 10.

[0068] The shape of the rotor 30 is not limited to the form shown in the above embodiment. Specifically, the outer and inner diameters of the rotor core 31, the stacking thickness, the number of poles, etc., can be arbitrarily designed according to the desired characteristics of the rotating electric machine 10.

[0069] In the above embodiment, both the stator core 21 and the rotor core 31 are described as being laminated cores, but they do not necessarily have to be laminated cores. The second flux barrier 36 is not necessary. The third flux barrier 37 does not necessarily have to penetrate the rotor core 31 in the axial direction. In this case, the third flux barrier 37 may be connected only to a portion of the first side surface 34f1 in the axial direction.

[0070] In the above embodiment, one magnetic pole 33 is composed of two permanent magnets 32. However, the present invention is not limited thereto. For example, one magnetic pole 33 may be composed of one permanent magnet 32, three permanent magnets 32, or four or more permanent magnets 32. Other forms, including one or more permanent magnets 32 as a set of permanent magnets 32, can be appropriately adopted. For example, if a set of permanent magnets 32 is a single permanent magnet 32, this single permanent magnet 32 ​​may have a long rectangular shape in the direction perpendicular to the d-axis Ld in the plan view. In this case, the insertion hole 34 into which the single permanent magnet 32 ​​is inserted becomes the first insertion hole 34f. For example, if a set of permanent magnets 32 consists of three permanent magnets 32, and the three permanent magnets 32 are arranged in the circumferential direction, the following arrangement is also possible. In this case, the permanent magnet 32 ​​located in the center in the circumferential direction may be a long rectangle in the direction perpendicular to the d axis Ld in the plan view. Furthermore, in this case, the two permanent magnets 32 located on both sides in the circumferential direction may extend radially outward from the d axis Ld side to the q axis Lq side in the plan view. In this case, the insertion hole 34 into which the permanent magnet 32 ​​located furthest forward among the three or more permanent magnets 32 is inserted becomes the first insertion hole 34f.

[0071] Furthermore, without departing from the spirit of the present invention, the components in the above embodiments may be replaced with well-known components as appropriate, and the above-described modifications may be combined as appropriate. [Industrial applicability]

[0072] According to this invention, torque pulsation is reduced. Therefore, it has great industrial applicability. [Explanation of Symbols]

[0073] 10, 100 Rotating Electric Machines 20 stata 21 Stator Core 22 Coreback 23 Teeth 24 slots 30, 112 rotors 31 Rotor core 31a Outer surface 32 Permanent Magnets 32f front magnet 32ff part 32fr part 32r Rear Magnet 33 magnetic pole 34 Insertion holes 34f First insertion hole 34f1 1st side 35. First flux barrier (flux barrier extending forward from the first insertion hole) 35a Outer edge 36. Second Flux Barrier 37. Third Flux Barrier (Flux Barrier) 37a Inner end 37b Outer side 37c Barrier center position 37d Front end of barrier 37e Rear end of barrier 37g widening section 37h Connection 38 Bridge 50 cases 60 Rotation axis A Arrow B Arrow C arrow E1 inner area E2 area E3 inner area F forward G1 Graph G2 Graph G3 Graph G4 Graph Ld d axis Lq q-axis O center axis R rear Xm barrier connection location θm barrier central angle θs slot central angle θw Barrier opening angle

Claims

1. A ring-shaped stator, A rotating electric machine comprising a rotor disposed within the stator, The rotor is Rotor core and The rotor core is embedded in the rotor core and forms magnetic poles, and multiple sets of permanent magnets are arranged in the circumferential direction of the rotor core. The rotor core is A rotor core used in an embedded magnet type motor, Multiple sets of permanent magnets constituting magnetic poles are arranged in the circumferential direction of the rotor core. The rotor core has a plurality of insertion holes formed therein, which penetrate the rotor core in the axial direction and into which the permanent magnets are inserted. The rotor core has a flux barrier provided corresponding to at least one of the plurality of magnetic poles. The aforementioned insertion holes include a first insertion hole into which the permanent magnet, which is positioned towards the front of the rotation of each of the magnetic poles, is inserted. The flux barrier is provided on a side surface facing the short direction in the first insertion hole, at a position opposite to the first side surface on the radially outer side of the rotor core, and is connected to the first side surface. The flux barrier is a rotating electric machine in which the circumferential barrier opening angle θw of the rotor is satisfied by the following equations (1) and (2) on the outer peripheral surface located radially outside the rotor. When (2 / 5)θs < θm < (3 / 4)θs, 0<θw<(22 / 7)θm−(44 / 35)θs…(1) When (3 / 4)θs ≤ θm < (9 / 10)θs, 0<θw<-(22 / 3)θm+(33 / 5)θs…(2) θs=2π / Nslot...(3) Here, Nslot in equation (3) above means the number of slots in the stator. θm represents the barrier center angle formed between the circumferential center position on the outer peripheral surface and the radially outer end of the flux barrier extending forward from the first insertion hole.

2. A ring-shaped stator, A rotating electric machine comprising a rotor disposed within the stator, The rotor is Rotor core and The rotor core is embedded in the rotor core and forms magnetic poles, and multiple sets of permanent magnets are arranged in the circumferential direction of the rotor core. The rotor core is A rotor core used in an embedded magnet type motor, Multiple sets of permanent magnets constituting magnetic poles are arranged in the circumferential direction of the rotor core. The rotor core has a plurality of insertion holes formed therein, which penetrate the rotor core in the axial direction and into which the permanent magnets are inserted. The rotor core has a flux barrier provided corresponding to at least one of the plurality of magnetic poles. The aforementioned insertion holes include a first insertion hole into which the permanent magnet, which is positioned towards the front of the rotation of each of the magnetic poles, is inserted. The flux barrier is provided in close proximity to the first insertion hole at a position facing the first radially outer side of the rotor core, among the sides of the first insertion hole facing the short side, so as to divide the magnetic flux generated from the permanent magnet inserted into the first insertion hole in the circumferential direction. The flux barrier is a rotating electric machine in which the circumferential barrier opening angle θw of the rotor is satisfied by the following equations (1) and (2) on the outer peripheral surface located radially outside the rotor. When (2 / 5)θs < θm < (3 / 4)θs, 0<θw<(22 / 7)θm−(44 / 35)θs…(1) When (3 / 4)θs ≤ θm < (9 / 10)θs, 0<θw<-(22 / 3)θm+(33 / 5)θs…(2) θs=2π / Nslot...(3) Here, Nslot in equation (3) above means the number of slots in the stator. θm represents the barrier center angle formed between the circumferential center position on the outer peripheral surface and the radially outer end of the flux barrier extending forward from the first insertion hole.

3. The flux barrier has a portion that increases in the circumferential direction of the rotor core as it extends radially outward. The rotating electric machine according to claim 1 or 2.

4. The flux barrier blocks the magnetic flux generated from the permanent magnet inserted into the first insertion hole, specifically the magnetic flux that travels from the rearward-rotating side to the forward-rotating side at the magnetic pole. The rotating electric machine according to claim 1 or 2.

5. The rotating electric machine according to claim 1 or 2, wherein a bridge is provided in the portion of the rotor core located radially outward from the flux barrier.

6. A method for designing a rotating electric machine according to claim 1 or 2, A method for designing a rotating electric machine, comprising the step of designing the position and shape of the flux barrier based on the magnetic flux located towards the forward rotation of the magnetic pole.

7. The method for designing a rotating electric machine according to claim 6, wherein in the above step, the position and shape of the flux barrier are designed such that, when the torque is maximum, the magnetic flux that generates torque in the forward direction of rotation from the magnetic flux near the rotational front of the magnetic pole is blocked, and when the torque is minimum, the magnetic flux that generates torque in the backward direction of rotation from the magnetic flux near the rotational front of the magnetic pole is blocked.

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