A rotating electric machine, a rotating electric machine system combining the rotating electric machine and an electric drive device, and an electric vehicle equipped with the rotating electric machine system.

Abstract

A rotary electric machine (100) is provided with: a rotor (4) having magnetic poles of a plurality of permanent magnets (43); an annular core back (22); and a stator (2) formed by stacking, in an axial direction of the rotor (4), a stator core (21) having a plurality of teeth (23) facing a circumferential surface of the rotor (4), wherein a winding slot (24) for winding a winding (25) is provided between a tooth (23) and the tooth (23) next to said tooth (23), a plurality of auxiliary grooves (26) respectively extending in the stacking direction are arranged on surfaces of tooth distal-end sections 23a of the teeth (23) facing the rotor (4), and S / P ≥ 3 is satisfied assuming that the number of magnetic poles in the rotor (4) is P and the number of winding slots (24) is S.

Description

Technical Field

[0004]

[0001] The present application relates to a rotating electric machine, a rotating electric machine system combining the rotating electric machine and a power drive device, and an electric vehicle equipped with the rotating electric machine system.

Background Art

[0002] In recent years, motors for electric vehicles are required to be low in vibration in addition to high efficiency and high output density, and methods for reducing torque ripple that causes vibration have been proposed. In motors for electric vehicles, distributed winding motors are adopted to reduce torque ripple, but the demand for further reduction of torque ripple is increasing. In an embedded magnet type rotor often adopted in motors for electric vehicles, it is widely known that torque and torque ripple can be adjusted by devising the magnet arrangement inside the rotor. However, since the magnet arrangement that maximizes torque is different from the magnet arrangement that minimizes torque ripple, torque ripple suppression is performed by superimposing a current that generates a torque ripple of opposite phase even in motor control, and the torque ripple of the entire motor is reduced. When suppressing torque ripple in motor control, the harmonic order of torque ripple that can be suppressed is limited by the control frequency. Therefore, it is important to reduce in advance, depending on the motor structure, the component of the order that cannot be reduced by control, paying attention to the harmonic order of torque ripple. An embedded magnet motor that reduces torque ripple by arranging one auxiliary groove at the tip of the teeth of the stator core in an embedded magnet type distributed winding motor has been disclosed.

Prior Art Documents

[0005] This application discloses technology to solve the above-mentioned problems, and aims to provide a rotating electric machine, a rotating electric machine system, and an electric vehicle that can reduce torque ripple of a higher order than slot harmonics, which is often difficult to suppress with motor control. [Means for solving the problem]

[0006] The rotating electric machine disclosed herein comprises a rotor having multiple permanent magnet poles, a stator formed by stacking an annular core back and a stator core having multiple teeth facing the circumferential surface of the rotor in the axial direction of the rotor, and winding slots for winding wires are provided between the teeth and adjacent teeth. It was a rotating electric machine Multiple auxiliary grooves extending in the stacking direction are arranged on the surface of the tooth tip of the tooth facing the rotor, and if the number of magnetic poles of the rotor is P and the number of winding slots is S, then S / P ≥ 3. Furthermore, if we consider the fundamental wave component of the current frequency driving the rotating electric machine as the first order, and let n be a natural number, and the order of the torque ripple being reduced to be 6n, then 6n > 2S / P is satisfied. The stator is configured such that the stator has a smaller 6n-th order torque ripple when multiple stator cores with different positions of the auxiliary grooves at the tip of the teeth are combined, in proportion to the stacking thickness of the stator cores, compared to the 6n-th order torque ripple when only one type of stator core with the maximum 6n-th order torque ripple per unit stacking thickness is used. It is. Furthermore, the rotating electric machine disclosed herein comprises a stator formed by stacking a rotor having multiple permanent magnet poles, an annular core back, and a stator core having multiple teeth facing the circumferential surface of the rotor in the axial direction of the rotor, wherein winding slots for winding wires are provided between the teeth and adjacent teeth, and a plurality of auxiliary grooves extending in the stacking direction are arranged on the surface of the tooth tip of each tooth facing the rotor, and if the number of magnetic poles of the rotor is P and the number of winding slots is S, then S / P ≥ 3 is satisfied, and the stator core having teeth without the auxiliary grooves is stacked The stator is further comprised of layers, and if the fundamental wave component of the current frequency driving the rotating electric machine is taken as the first order, and n is a natural number, the order of the torque ripple being reduced is 6n, then the stator is configured such that the ratio of the stacking thickness of the stator cores is such that the 6n-th order torque ripple is smaller when the stator is configured with a combination of the stator cores having the auxiliary grooves at the tip of the teeth and the stator core without the auxiliary grooves at the tip of the teeth, compared to the 6n-th order torque ripple when the stator is configured with only one type of stator core that satisfies 6n > 2S / P and has the maximum 6n-th order torque ripple per unit stacking thickness. Furthermore, the rotating electric machine disclosed in this application comprises a stator formed by stacking a rotor having multiple permanent magnet poles, an annular core back, and a stator core having multiple teeth facing the circumferential surface of the rotor in the axial direction of the rotor, and winding slots for winding wires are provided between the teeth and adjacent teeth, wherein a plurality of auxiliary grooves extending in the stacking direction are arranged on the surface of the tooth tip of each tooth that faces the rotor, and if the number of magnetic poles of the rotor is P and the number of winding slots is S, then S / P ≥ 3 is satisfied, and the width of the narrowest part of the shoe, which is the circumferentially extended portion of the tooth tip, is 2 times or more the thickness of the electromagnetic steel sheet constituting the stator core. Furthermore, the rotating electric machine disclosed in this application comprises a stator formed by stacking a rotor having multiple permanent magnet poles, an annular core back, and a stator core having multiple teeth facing the circumferential surface of the rotor in the axial direction of the rotor, and winding slots for winding wires are provided between the teeth and adjacent teeth, wherein a plurality of auxiliary grooves extending in the stacking direction are arranged on the surface of the tooth tip of each tooth facing the rotor, and if the number of magnetic poles of the rotor is P and the number of winding slots is S, then S / P ≥ 3 is satisfied, and if the tip of each tooth is separated by the auxiliary groove, and the tip angle on the circumferential center side of the tooth tip is δ1 and the tip angles on the circumferential end side are δ2, then δ1 ≥ 2δ2 is satisfied. The rotating electric machine system disclosed in this application combines the above-mentioned rotating electric machine with a power drive device that controls the rotation of the rotating electric machine and suppresses torque ripple of the rotating electric machine. The electric vehicle disclosed herein is equipped with the above-described rotating electric machine system. [Effects of the Invention]

[0007] The rotating electric machine disclosed in this application provides a rotating electric machine that can reduce torque ripple of a higher order than slot harmonics, which is often difficult to suppress with motor control. The rotating electric machine system disclosed herein provides a rotating electric machine system that can reduce torque ripple of a higher order than slot harmonics, which is often difficult to suppress with motor control. According to the electric vehicle disclosed in this application, an electric vehicle can be obtained that is equipped with a rotating electric machine system capable of reducing torque ripple of a higher order than the slot harmonics, which is often difficult to suppress with motor control. [Brief explanation of the drawing]

[0008] [Figure 1] This is an axial cross-sectional view of one-eighth of the circumferential direction of a rotating electric machine according to Embodiment 1. [Figure 2] This is an enlarged view of the teeth of the stator core of a rotating electric machine according to Embodiment 1. [Figure 3] This is a perspective view of the stator core of a rotating electric machine according to Embodiment 1, covering one-eighth of the circumferential direction. [Figure 4] This is an axial cross-sectional view of the rotor of a rotating electric machine according to Embodiment 1, with a circumferential direction of 1 / 8. [Figure 5] This is an axial cross-sectional view of the stator core (without auxiliary grooves at the tip of the teeth) of a rotating electric machine according to Embodiment 1, with a circumference of 1 / 8. [Figure 6] This shows the analysis results of the 24th order torque ripple with respect to the auxiliary groove position of the rotating electric machine according to Embodiment 1. [Figure 7] This is an enlarged view of the teeth of the stator core of a modified example (square auxiliary groove shape) of the rotating electric machine according to Embodiment 1. [Figure 8] This is an enlarged view of the teeth of the stator core of a modified example (triangular auxiliary groove) of the rotating electric machine according to Embodiment 1. [Figure 9] This is an axial cross-sectional view of one-eighth of the circumferential direction of a modified example of the rotating electric machine according to Embodiment 1 (8 poles, 96 slots, double V-shaped embedded magnet rotor). [Figure 10]Axial sectional view of one-sixth in the circumferential direction of a modified example of a rotating electrical machine (6 poles, 54 slots, double V-shaped embedded magnet rotor) according to Embodiment 1. [Figure 11] Axial sectional view of one-eighth in the circumferential direction of a modified example of a rotating electrical machine (8 poles, 48 slots, single V-shaped embedded magnet rotor) according to Embodiment 1. [Figure 12] Axial sectional view of one-eighth in the circumferential direction of a modified example of a rotating electrical machine (8 poles, 48 slots, triple V-shaped embedded magnet rotor) according to Embodiment 1. [Figure 13] Enlarged view of a tooth of a stator core of a rotating electrical machine according to Embodiment 2. [Figure 14] Enlarged view of a tooth of a stator core of a rotating electrical machine according to Embodiment 2. [Figure 15] Perspective view of one-eighth in the circumferential direction of a stator core of a rotating electrical machine according to Embodiment 2. [Figure 16] Explanatory diagram of the phase difference of the 24th torque ripple with respect to the position of an auxiliary groove of a rotating electrical machine according to Embodiment 2. [Figure 17] Perspective view of one-eighth in the circumferential direction of a stator core of a modified example (change in ratio of stator core) of a rotating electrical machine according to Embodiment 2. [Figure 18] Perspective view of one-eighth in the circumferential direction of a stator core of a rotating electrical machine according to Embodiment 3. [Figure 19] Perspective view of one-eighth in the circumferential direction of a stator core of a rotating electrical machine according to Embodiment 4. [Figure 20] Enlarged view of the tip of a tooth of a stator core of a rotating electrical machine according to Embodiment 4. [Figure 21] Enlarged view of the tip of a tooth of a stator core which is a modified example of a rotating electrical machine according to Embodiment 4. [Figure 22] Perspective view of one-eighth in the circumferential direction of a stator core of a rotating electrical machine according to Embodiment 5. [Figure 23] Axial sectional view of one-eighth in the circumferential direction of a rotating electrical machine according to Embodiment 6. [Figure 24] Axial sectional view of one-eighth in the circumferential direction of a rotating electrical machine according to Embodiment 6. [Figure 25] This is a perspective view of the stator core of a rotating electric machine according to Embodiment 6, showing one-eighth of the circumferential direction. [Figure 26] This is an axial cross-sectional view of the rotor of a rotating electric machine according to Embodiment 6, with a circumferential direction of 1 / 8. [Figure 27] This is an axial cross-sectional view of one-eighth of the circumferential direction of a rotating electric machine according to Embodiment 6. [Figure 28] This shows the analysis results of the 6th to 24th order torque ripple amplitudes of the rotating electric machine according to Embodiment 6. [Figure 29] This shows the analysis results of the amplitude of the 18th-order torque ripple with respect to the position of the auxiliary groove of the rotating electric machine according to Embodiment 6. [Figure 30] This is an explanatory diagram of the phase difference of a rotating electric machine according to Embodiment 6. [Figure 31] This shows the analysis results of the amplitude of the 24th-order torque ripple with respect to the position of the auxiliary groove of the rotating electric machine according to Embodiment 6. [Figure 32] This is an explanatory diagram of the phase difference of a rotating electric machine according to Embodiment 6. [Figure 33] This is a conceptual diagram of an electric vehicle equipped with a rotating electric motor according to Embodiments 1 to 6. [Modes for carrying out the invention]

[0009] Embodiment 1. Embodiment 1 comprises a stator formed by stacking a rotor having multiple permanent magnet poles, an annular core back, and a stator core having multiple teeth facing the circumferential surface of the rotor in the axial direction of the rotor. Winding slots for winding wires are provided between teeth and adjacent teeth, and multiple auxiliary grooves extending in the stacking direction are arranged on the surface of the tooth tip of each tooth facing the rotor. If the number of magnetic poles of the rotor is P and the number of winding slots is S, then S / P ≥ 3 is satisfied.

[0010] The following are figures relating to Embodiment 1 of the rotating electric machine: Figure 1 is an axial cross-sectional view of the circumferential 1 / 8 of the rotating electric machine; Figure 2 is an enlarged view of the teeth of the stator core of the rotating electric machine; Figure 3 is a perspective view of the circumferential 1 / 8 of the stator core of the rotating electric machine; Figure 4 is an axial cross-sectional view of the circumferential 1 / 8 of the rotor of the rotating electric machine; Figure 5 is an axial cross-sectional view of the circumferential 1 / 8 of the stator core of the rotating electric machine (without auxiliary grooves at the tip of the teeth); Figure 6 is the analysis result of the 24th order torque ripple with respect to the auxiliary groove position of the rotating electric machine; and a modified example of the rotating electric machine (with auxiliary groove shape) This will be explained based on Figures 7 (a square-shaped stator core teeth view), Figure 8 (a modified example of a rotating electric machine with a triangular auxiliary groove teeth view), Figure 9 (an axial cross-sectional view of one-eighth of the circumferential direction of a modified example of a rotating electric machine with 8 poles and 96 slots, and a double V-shaped embedded magnet rotor), and Figures 10 to 12 (an axial cross-sectional view of one-eighth of the circumferential direction of modified examples of a rotating electric machine with 6 poles and 54 slots, a double V-shaped embedded magnet rotor, an 8 pole and 48 slots, and a single V-shaped embedded magnet rotor, and an 8 pole and 48 slots, triple V-shaped embedded magnet rotor). In each figure, identical or corresponding parts are indicated by the same reference numeral, and redundant explanations are omitted. Furthermore, in the following explanation, when the terms axis (direction), diameter (direction), inner diameter (side, direction), outer diameter (side, direction), and circumference (direction) are used, unless otherwise specified, they refer to the axis of rotation (direction), radius (direction), relative to the radial center (side, direction), relative to the radial outward (side, direction), and circumference (direction) of the axis of rotation in a cylindrical coordinate system centered on the rotor's axis of rotation.

[0011] First, the basic configuration of the rotating electric machine 100 of Embodiment 1 will be explained based on Figures 1 to 4. As shown in Figure 1, the rotating electric machine according to Embodiment 1 consists of a stator 2 and a rotor 4 which is coaxially arranged radially inward of the stator 2 via an air gap 3. The stator 2 has a stator core 21 made of electrical steel sheet, which consists of an annular core back 22 and teeth 23 extending radially inward from the core back 22. Coils 25 are arranged in the winding slots 24 of the stator core 21, which are regions enclosed by adjacent teeth 23 and the core back 22. The winding slots 24 are roughly rectangular in shape to accommodate the use of flat wire for the coils 25. In this embodiment 1, the stator core 21 has 48 teeth 23 evenly spaced in the circumferential direction, and 48 winding slots 24 are provided. In other words, if S is the number of winding slots 24, then S = 48. In this embodiment 1, the coil 25 is wound on the stator 2 in a distributed winding structure and connected in series with the coils 25 located six adjacent winding slots 24 in the circumferential direction, and a three-phase alternating current is passed through them. In Figure 1, to clarify the directions explained earlier, the direction towards the center of the rotation axis (the vertical direction in Figure 1) is labeled as the radial direction (R), and the direction along the rotational direction around the rotation axis is labeled as the circumferential direction (P). The same applies to the following drawings.

[0012] As shown in Figure 2, the teeth 23 of the stator core 21 of the rotating electric machine 100 according to Embodiment 1 are composed of a tooth extension portion 23b that extends radially inward from the core back 22 and a shoe 27 that protrudes symmetrically in the circumferential direction from the tooth tip portion 23a. On the radially inward surface of the tooth tip portion 23a, one semicircular auxiliary groove 26 is arranged at approximately symmetrical positions within the dimensional tolerance range with respect to the tooth central axis 23c that passes from the rotation axis of the rotor 4 to the circumferential center point of the tooth tip portion 23a. Here, if the auxiliary groove position is the electrical angle of the angle between the tooth central axis 23c and the straight line connecting the rotation axis of the rotor 4 and the center of the semicircle of the auxiliary groove 26, then in Embodiment 1, it is positioned at α = 9.0 degrees.

[0013] As shown in Figure 3, the stator 2 of the rotating electric machine 100 according to Embodiment 1 includes a stator core 21 formed by stacking the aforementioned electromagnetic steel sheets by a distance L in the axial direction. In Figure 3, to clarify the directions explained earlier, the rotation axis direction of the rotor 4 (the vertical direction in Figure 3) is labeled as the axial direction (X), and the direction along the rotational direction around the rotation axis is labeled as the circumferential direction (P). The same applies to the following drawings.

[0014] As shown in Figure 4, the rotor 4 of the rotating electric machine 100 according to Embodiment 1 comprises an annular rotor core 41 and a pair of first-layer magnet slots 42f and second-layer magnet slots 42s arranged opposite each other, such that the distance between them decreases as you move radially inward from the d-axis of the rotor core, which is the main direction of the magnetic flux created by the magnetic poles (i.e., the distance on the radially inward is narrower than the distance on the radially outward). A first-layer permanent magnet 43f and a second-layer permanent magnet 43s are inserted into each magnet slot. When referring to the first layer magnet slot 42f and the second layer magnet slot 42s together, they are referred to as magnet slot 42, and when referring to the first layer permanent magnet 43f and the second layer permanent magnet 43s together, they are referred to as permanent magnet 43. Hereafter, this rotor structure will be referred to as a double V-shaped embedded magnet rotor. The permanent magnets 43 have a flat plate shape and are magnetized in parallel along their short sides and all facing the same direction radially. Eight sets of these four permanent magnets 43 are arranged in the circumferential direction, with the magnetization direction of adjacent permanent magnets in the circumferential direction alternating between radially outward and radially inward.

[0015] Therefore, if the number of magnetic poles of rotor 4 is P, then P = 8. Here, if we let β be the polar arc angle, which is the electrical angle formed in the direction of rotation of rotor 4 by two straight lines connecting the rotation center of rotor 4 and the d-axis side corner on the rotor surface side of magnet slot 42, then the polar arc angle of the first layer magnet slot 42f is β1, and the polar arc angle of the second layer magnet slot 42s is β2. In this embodiment 1, the polar arc angles are set to β1 = 65 degrees and β2 = 135 degrees. In this way, a 3-phase motor with S / P=6, that is, an 8-pole, 48-slot distributed winding motor with 2 for every pole and every phase, is constructed.

[0016] Next, the effects of this embodiment 1 will be explained. In the case of an 8-pole, 48-slot distributed winding motor, the explanation will focus on the 24th-order torque ripple, which is difficult to suppress with motor control.

[0017] Figure 5 is an axial cross-sectional view of the third stator core 21C, which has a third tooth 23C without an auxiliary groove at the tooth tip, at 1 / 8 of the circumferential direction.

[0018] Here, in order to clarify the characteristics of the rotating electric machine of this application, we will explain the principle for distinguishing teeth, stator core, and stator based on the difference in the position of the auxiliary grooves at the tip of the teeth and the presence or absence of auxiliary grooves. The tooth 23 (α=9.0 degrees) described in Figures 1 to 4, which is the basis of this invention, will be referred to as the first tooth 23A, and the stator core and stator equipped with it will be appropriately described as the first stator core 21A and the first stator 2A, respectively. Also, the figure 14 The tooth with the auxiliary groove described below located near the central axis of the tooth will be referred to as the second tooth 23B, and the stator core and stator equipped with it will be referred to as the second stator core 21B and the second stator 2B, respectively. Furthermore, as shown in Figure 5, teeth without auxiliary grooves are designated as third teeth 23C, and stator cores and stators equipped with these teeth are appropriately referred to as third stator core 21C and third stator 2C, respectively.

[0019] Figure 6 shows the 2D-FEM analysis results illustrating the change in the amplitude of the 24th-order torque ripple with respect to the position of the auxiliary groove 26 of the rotating electric machine according to Embodiment 1. The change in torque ripple when the auxiliary groove 26 is present will be explained, using the torque ripple generated when the third stator core 21C with the third teeth 23C without the auxiliary groove 26 shown in Figure 5 is used as a reference.

[0020] As shown in Figure 6, the amplitude of the 24th-order torque ripple changes when the auxiliary groove position α described in Figure 2 is changed, and it can be seen that there is an α such that the 24th-order torque ripple is smaller than that of the third stator core 21C without the auxiliary groove 26. Furthermore, when the auxiliary groove position α = 9.0 degrees, which is the position in Embodiment 1, the 24th-order torque ripple is reduced by approximately 33% compared to the third stator core 21C without the auxiliary groove 26. Therefore, the rotating electric machine 100 of Embodiment 1 is a three-phase motor with S / P=6, and the slot harmonic order is 12th order, which makes it possible to reduce torque ripple of an order higher than the slot harmonic.

[0021] Therefore, by arranging the auxiliary groove 26 on the tooth tip 23a, the amplitude of torque ripples that are larger than the slot harmonics can be changed, thereby reducing these torque ripples.

[0022] Furthermore, although the 24th-order torque ripple was described in this embodiment 1, the effect of torque ripple reduction by the auxiliary groove 26 can be obtained for any order higher than the slot harmonic.

[0023] Furthermore, by arranging one auxiliary groove 26 on each tooth tip 23a at a position symmetrical with respect to the tooth central axis 23c, the number of auxiliary grooves 26 can be minimized, and the torque can be increased while obtaining the torque ripple reduction effect described above. In a rotating electric machine on which a distributed winding coil is wound, as in this embodiment 1, the teeth 23 are densely arranged and the width of the tooth tip 23a is reduced. Therefore, the torque ripple reduction effect of this embodiment 1 can be obtained while keeping the difficulty of machining the auxiliary grooves 26, the strength and durability near the auxiliary grooves within a relatively reasonable range.

[0024] Furthermore, when multiple auxiliary grooves 26 are arranged on the tooth tip portion 23a, as shown in Embodiment 1, symmetrical arrangement with respect to the tooth central axis 23c is more effective in reducing torque ripple. However, the embodiments of this embodiment are not limited to strictly symmetrical arrangements. As long as the multiple auxiliary grooves 26 are arranged so as to be distributed generally evenly without any particular bias in the circumferential direction of the tip of the tooth 23, the effect of reducing torque ripple in Embodiment 1 can be obtained to a certain extent.

[0025] Furthermore, by making the auxiliary groove shape semicircular, the corners of the auxiliary groove 26 are eliminated, improving mold life and reducing manufacturing costs.

[0026] Furthermore, although the rotor 4 in this embodiment 1 is of the embedded magnet type, the effect of reducing torque ripple in this embodiment 1 can be obtained even if the polar arc angle β is not the value shown in this embodiment 1. Moreover, although the rotor 4 in this embodiment 1 is of the embedded magnet type, by changing the polar arc angle β, the torque ripple of the slot harmonic order and lower orders can also be reduced, and the torque ripple of each order can be suppressed in a balanced manner.

[0027] Next, a modified example of Embodiment 1 will be described. Figure 7 is an enlarged view of the teeth 23 of a stator core 21, which is a modified example of the rotating electric machine according to Embodiment 1, in which the auxiliary groove shape is square. In the figure, the square-shaped auxiliary groove is labeled as auxiliary groove 26s. Figure 8 is an enlarged view of the teeth 23 of a stator core 21, which is a modified example of the rotating electric machine according to Embodiment 1, in which the auxiliary groove shape is triangular. In the figure, the triangular auxiliary groove is labeled as auxiliary groove 26t.

[0028] Figure 9 is an axial cross-sectional view of one-eighth of the circumferential direction of a rotating electric machine, which is a modified example of the rotating electric machine according to Embodiment 1, having 8 poles, 96 slots, and a double V-shaped embedded magnet rotor. In Figure 9, this is referred to as the rotating electric machine 101. Figure 10 is an axial cross-sectional view of one-sixth of the circumferential direction of a rotating electric machine, which is a modified example of the rotating electric machine according to Embodiment 1, having 6 poles, 54 slots, and a double V-shaped embedded magnet rotor. In Figure 10, this is referred to as the rotating electric machine 102. Figure 11 is an axial cross-sectional view of one-eighth of the circumferential direction of an 8-pole, 48-slot, single-layer V-shaped embedded magnet rotor, which is a modified example of the rotating electric machine according to Embodiment 1. 103 That is what they say. Figure 12 is an axial cross-sectional view of one-eighth of the circumferential direction of an 8-pole, 48-slot, triple V-shaped embedded magnet rotor, which is a modified example of the rotating electric machine according to Embodiment 1. 104 This is the case. Figure 12 also shows the third layer magnet slot 42t and the third layer permanent magnet 43t.

[0029] As shown in Figures 7 and 8, the auxiliary groove shape of the rotating electric machine according to Embodiment 1 was semicircular, but regardless of the shape, such as a square or triangle, the above torque ripple reduction effect can be obtained as long as the structure is cut from the tooth tip 23a toward the outer circumference.

[0030] As shown in Figures 9 and 10, even when the combination of the number of magnetic poles and the number of slots is different, the torque ripple reduction effect of this embodiment 1 can be obtained as long as S / P ≥ 3 is satisfied.

[0031] As shown in Figures 11 and 12, even with embedded magnet types that have different rotor structures, the torque ripple reduction effect of this embodiment 1 can be obtained as long as S / P ≥ 3 is satisfied. Furthermore, since the polar arc angle can be changed, torque ripple of the slot harmonic order and lower orders can also be reduced.

[0032] Furthermore, the triple V-shaped structure in Figure 12 offers even greater freedom in magnet placement, making it easier to bring the magnetic flux density distribution in the air gap 3 closer to a sine wave.

[0033] Furthermore, in Embodiment 1, the winding slot 24 is made into a roughly rectangular shape assuming the use of flat rectangular wire, but the winding slot 24 may be made into a round wire instead of a roughly rectangular shape.

[0034] As described above, the rotating electric machine of Embodiment 1 can reduce torque ripples by changing the amplitude of torque ripples that are larger than the slot harmonics, by arranging auxiliary grooves at the tip of the teeth.

[0035] Embodiment 2. Embodiment 2 is a configuration in which two types of stator cores with different auxiliary groove positions are combined in the axial direction.

[0036] Regarding the rotating electric machine of Embodiment 2, the differences from Embodiment 1 will be explained based on Figure 13, an enlarged view of the teeth of the stator core of the rotating electric machine; Figure 14, an enlarged view of the teeth of the stator core of the rotating electric machine; Figure 15, a perspective view of one-eighth of the circumferential direction of the stator core of the rotating electric machine; Figure 16, an explanatory diagram of the phase difference of the 24th order torque ripple with respect to the auxiliary groove position of the rotating electric machine; and Figure 17, a perspective view of one-eighth of the circumferential direction of the stator core of a modified rotating electric machine (change in the ratio of the stator core). In the diagram of Embodiment 2, parts that are the same as or equivalent to those in Embodiment 1 are denoted by the same reference numerals. In order to distinguish it from Embodiment 1, Embodiment 2 is referred to as the rotating electric machines 200 and 201.

[0037] First, the configuration of the rotating electric machine 200 of Embodiment 2 will be explained based on Figures 13 to 15, focusing on the teeth and stator core. The rotating electric machine 200 according to Embodiment 2 has a configuration in which two types of stator cores, a first stator core 21A and a second stator core 21B, with different auxiliary groove positions, are combined in the axial direction. The configuration of the rotor 4 is the same as in Embodiment 1. As shown in Figure 13, the auxiliary groove 26 of the first tooth 23A of the first stator core 21A is positioned such that the auxiliary groove position is α1 = 9.0 degrees. As shown in Figure 14, the auxiliary groove 26 of the second tooth 23B of the second stator core 21B is positioned such that the auxiliary groove position is α2 = 2.0 degrees.

[0038] As shown in Figure 15, the stator core 21AB of the rotating electric machine 100 according to Embodiment 2 is constructed by stacking the first stator core 21A with a stacking thickness of L1, the second stator core 21B with a stacking thickness of L2, the 24th-order torque ripple amplitude generated in the first stator core 21A being τ1, and the 24th-order torque ripple amplitude generated in the second stator core 21B being τ2, in an axial order stacking ratio of L1:L2=τ2:τ1. Furthermore, the stator core formed by stacking the first stator core 21A and the second stator core 21B is referred to as stator core 21AB. Thus, the rotating electric machine 200 of Embodiment 2 is configured as a 3-phase motor with S / P=6, that is, an 8-pole, 48-slot distributed winding motor where each pole and each phase is 2.

[0039] Next, the effects of the second embodiment of the rotating electric machine 200 will be described. Figure 16 shows the phase difference of the 24th-order torque ripple generated at the third stator core 21C without the auxiliary groove 26, relative to the position of the auxiliary groove 26 of the rotating electric machine 200 according to Embodiment 2, with reference to the phase of the 24th-order torque ripple.

[0040] As in Embodiment 2, when combining stator cores with different auxiliary groove positions, it is necessary to consider not only the amplitude of the torque ripple but also its phase. In the stator core 21AB of Embodiment 2, the auxiliary groove 26 is different from that of the stator core 21 of Embodiment 1. Therefore, the amplitude of the 24th-order torque ripple when the position of the auxiliary groove at the tooth tip 23a is changed is the same as in Figure 6. Furthermore, as shown in Figure 16, when the position of the auxiliary groove at the tooth tip 23a is changed, the phase of the 24th-order torque ripple also changes. As can be seen from Figure 16, the phase difference between the 24th-order torque ripples generated in the first stator core 21A and the second stator core 21B is approximately 180 degrees. Therefore, if the amplitude of the 24th-order torque ripple generated in the first stator core 21A is τ1 and the amplitude of the 24th-order torque ripple generated in the second stator core 21B is τ2, then the total 24th-order torque ripple amplitude τALL generated in the entire motor is: τALL=(τ2·L2-τ1·L1) / (L1+L2) It can be calculated using this method. In this second embodiment, since L1:L2=τ2:τ1, the 24th-order torque ripple can be reduced almost completely.

[0041] As described above, by combining two types of stator cores with different positions of the auxiliary grooves 26 in the axial direction, opposite-phase torque ripples can be superimposed, and 24th-order torque ripples can be suppressed more effectively. Furthermore, although the 24th-order torque ripple was described in this second embodiment, the torque ripple reduction effect of the auxiliary groove 26 can be obtained for any order higher than the slot harmonic.

[0042] Furthermore, by arranging one auxiliary groove 26 on each tooth tip 23a at a position symmetrical to the tooth central axis 23c, the number of auxiliary grooves 26 can be minimized, thereby achieving high torque while obtaining the torque ripple reduction effect described above. Furthermore, in a rotating electric machine on which a distributed winding coil is wound, as in this embodiment, the teeth 23 are densely arranged and the width of the tooth tip portion 23a is reduced. This allows for the reduction of torque ripple, as in this second embodiment, while keeping the machining difficulty of the auxiliary groove 26, the strength and durability near the auxiliary groove, etc., within a relatively reasonable range.

[0043] Furthermore, the stacking thicknesses of the first stator core 21A and the second stator core 21B are combined in a ratio of L1:L2=τ2:τ1, and the 24th-order torque ripple is made smaller than that of the second stator core 21B, which has a larger 24th-order torque ripple per unit stacking thickness. Furthermore, as in this embodiment, when the phase difference of the torque ripples generated by the two types of stator cores is 180 degrees, the torque ripples can be almost completely reduced by combining them according to the ratio of their respective torque ripple amplitudes.

[0044] Furthermore, when multiple auxiliary grooves 26 are arranged on the tooth tip portion 23a, arranging them symmetrically with respect to the tooth central axis 23c, as shown in Embodiment 2, is more effective in reducing torque ripple. However, the configuration of this second embodiment is not limited to a strictly symmetrical arrangement. As long as the multiple auxiliary grooves 26 are arranged so as to be distributed generally evenly without any particular bias in the circumferential direction of the tooth tip portion 23a, the effect of reducing torque ripple in this second embodiment can be obtained to a certain extent.

[0045] Furthermore, by making the auxiliary groove 26 semi-circular in shape, the corners of the auxiliary groove 26 are eliminated, improving mold life and reducing manufacturing costs.

[0046] Furthermore, although the rotor 4 in this embodiment is of the embedded magnet type, the effect of reducing torque ripple in this embodiment can be obtained even if the pole arc angle β is not the value shown in this embodiment. Furthermore, although the rotor 4 in this embodiment is of the embedded magnet type, by changing the pole arc angle β, the torque ripple of the slot harmonic order and lower orders can also be reduced, and the torque ripple of each order can be suppressed in a balanced manner. Furthermore, because the rotor 4 of this embodiment has a double V-shaped structure, there is a high degree of freedom in the arrangement of the magnets, making it easy to bring the magnetic flux density distribution in the air gap 3 closer to a sine wave.

[0047] Next, a modified example of Embodiment 2 will be described. Figure 17 is a perspective view of the stator core 21AB at 1 / 8 of its circumference when the ratio of the first stator core 21A to the second stator core 21B of the rotating electric machine 200 according to Embodiment 2 is changed. As shown in Figure 17, if two types of stator cores are combined in a ratio of L1:L2=4:1, the torque ripple amplitude will be smaller than that generated by the stator core 21 without the auxiliary groove 26. In Embodiment 2, two types of stator cores were combined in a ratio that completely suppressed 24th-order torque ripple. However, by combining them in a ratio that is smaller than the torque ripple amplitude generated by the stator core 21C without the auxiliary groove 26, the effect of reducing 24th-order torque ripple can be obtained.

[0048] Furthermore, although this embodiment illustrates a configuration combining two types of stator cores, the torque ripple reduction effect of this embodiment can also be obtained when combining three or more types of stator cores with different auxiliary groove positions. Furthermore, by combining three types of stator cores with different auxiliary groove positions, and ensuring that their phase difference is 120 degrees, torque ripple can be almost completely suppressed, similar to this embodiment. Furthermore, in Embodiment 2, the stacking thicknesses of the first stator core 21A and the second stator core 21B are combined in the ratio L1:L2=τ2:τ1. However, if the combination is made in a ratio smaller than the 24th-order torque ripple per unit stacking thickness of each stator core, the 24th-order torque ripple can be reduced.

[0049] Furthermore, although not shown in the figures, the auxiliary groove 26 in Embodiment 2 was semicircular in shape, but regardless of shape, such as a square or triangle, the torque ripple reduction effect can be obtained as long as the structure is cut from the tooth tip 23a toward the outer circumference. Furthermore, although not shown in the figures, the torque ripple reduction effect of this embodiment can be obtained even when the combination of the number of magnetic poles and the number of slots is different, as long as S / P ≥ 3 is satisfied. Furthermore, although not shown in the diagram, even with embedded magnet type rotors that have a different rotor structure, the torque ripple reduction effect of this embodiment can be obtained as long as S / P ≥ 3 is satisfied. Furthermore, because the polar arc angle can be changed, torque ripple of the slot harmonic order and lower orders can also be reduced. Furthermore, while Embodiment 2 assumes the use of flat rectangular wire, round wire can be used, and the winding slot 24 does not necessarily have to be approximately rectangular in shape.

[0050] As described above, the rotating electric machine of Embodiment 2 can reduce torque ripples by arranging auxiliary grooves at the tip of the teeth, thereby changing the amplitude of torque ripples that are larger than the slot harmonics. Furthermore, torque ripples can be reduced by utilizing the phase difference of the torque ripples.

[0051] Embodiment 3. Embodiment 3 is a configuration in which two types of stator cores with different auxiliary groove positions are combined axially so that one side sandwiches the other.

[0052] The third embodiment of the rotating electric machine will be explained, focusing on the differences from embodiments 1 and 2, based on Figure 18, a perspective view of the stator core of the rotating electric machine, showing one-eighth of the circumference. In the diagram of Embodiment 3, parts that are the same as or corresponding to those in Embodiment 1 are denoted by the same reference numerals. In order to distinguish it from Embodiment 1, Embodiment 3 is referred to as the rotating electric machine 300.

[0053] First, the configuration of the rotating electric machine 300 of Embodiment 3 will be described with reference to Figure 18. The basic configuration of the rotating electric machine 300 in Embodiment 3 is the same as in Embodiment 2. However, as shown in Figure 18, when stacking the stator cores in the axial direction, the second stator core 21B is sandwiched between the first stator core 21A, which is divided into approximately two axial sections within the dimensional tolerance range.

[0054] By configuring it in this way, the structure becomes symmetrical in the axial direction. In addition to the effects of Embodiment 2, this configuration balances the electromagnetic force applied to the rotor 4 regardless of its position in the axial direction, suppresses vibration, and prevents damage to the bearings. Furthermore, the same effect can be achieved even if the relative positions of the first stator core 21A and the second stator core 21B are reversed.

[0055] As described above, the rotating electric machine of Embodiment 3 can reduce torque ripples by arranging auxiliary grooves at the tip of the teeth, thereby changing the amplitude of torque ripples that are larger than the slot harmonics. Furthermore, the electromagnetic force applied to the rotor can be balanced.

[0056] Embodiment 4. Embodiment 4 is a configuration that combines a stator core with an auxiliary groove and a stator core without the auxiliary groove 26.

[0057] The differences between the rotating electric machine of Embodiment 4 and Embodiment 1 will be explained based on Figure 19, a perspective view of one-eighth of the circumferential direction of the stator core of the rotating electric machine; Figure 20, an enlarged view of the tip of the teeth of the stator core of the rotating electric machine; and Figure 21, an enlarged view of the tip of the teeth of a modified stator core of the rotating electric machine. In the diagram of Embodiment 4, parts that are the same as or corresponding to those in Embodiment 1 are denoted by the same reference numerals. In order to distinguish it from Embodiment 1, Embodiment 4 is referred to as the rotating electric machine 400.

[0058] First, the configuration of the rotating electric machine 400 of Embodiment 4 will be explained based on Figures 19 to 21. The rotating electric machine 400 of Embodiment 4 has a configuration that combines a first stator core 21A with an auxiliary groove 26 as shown in Figure 1 and a third stator core 21C without an auxiliary groove 26 as shown in Figure 5. As shown in Figure 19, if the stacking thickness of the first stator core 21A is LA and the stacking thickness of the third stator core 21C is LC, then they are stacked sequentially in the axial direction so that LA:LC = 1:9. Furthermore, the stator core formed by stacking the first stator core 21A and the third stator core 21C is referred to as stator core 21AC.

[0059] Furthermore, as shown in Figure 20, the electrical angle of the tooth tip angle on the side of the central axis 23c of the tooth tip 23a (i.e., the side of the circumferential center point of the tooth tip 23a) is defined as δ1, and the electrical angles of the two tooth tip angles on the circumferential end side are defined as δ2. Then, the shoe width, which is the narrowest part of the shoe 27 that extends circumferentially from the tooth tip 23a, is defined as Wshu. In Embodiment 4, the auxiliary grooves 26 are arranged such that δ1 ≥ 2·δ2. Furthermore, in Embodiment 4, the shoe width Wshu is more than twice the thickness of the electromagnetic steel sheet constituting the first stator core 21A.

[0060] Next, the effects of the rotating electric machine 400 of Embodiment 4 will be described. As shown in Figure 6, the 24th-order torque ripple amplitude generated in the first stator core 21A is approximately 15% of that of the third stator core 21C. Therefore, as in Embodiment 1, using only the first stator core 21A minimizes the 24th-order torque ripple amplitude. However, by placing the auxiliary groove 26 at the tooth tip 23a, the torque decreases compared to when the auxiliary groove 26 is not present.

[0061] On the other hand, if we let θ be the phase difference between the 24th-order torque ripple generated in the first stator core 21A and the third stator core 21C, and let τA be the amplitude of the 24th-order torque ripple generated in the first stator core 21A and τC be the amplitude of the 24th-order torque ripple generated in the third stator core 21C, then the total 24th-order torque ripple amplitude τALL generated in the entire motor is: τALL=[√((τA・LA+τC・LC・cos?θ)^2+(τC・LC・s in?θ)^2)] / (LA+LC) It can be calculated using this method. As shown in Figure 16, θ is approximately 150 degrees, which is greater than 90 degrees. Therefore, because the phase difference of the 24th-order torque ripple is greater than 90 degrees, the amplitude of the 24th-order torque ripple can be reduced more effectively.

[0062] Furthermore, while the polar arc angles of the magnet slots 42 of the rotor 4 exemplified in this embodiment are β1 = 65 degrees and β2 = 135 degrees, the torque ripple reduction effect of this embodiment can be further enhanced if the range is 50 ≤ β1 ≤ 70 and 130 ≤ β2 ≤ 140. Furthermore, by using only two types of stator cores in combination, the number of stator core types can be minimized, thereby reducing manufacturing costs. Furthermore, by using a third stator core 21C without the auxiliary groove 26, higher torque can be achieved compared to when the system is composed solely of the first stator core 21A which has the auxiliary groove 26. Furthermore, by combining the first stator core 21A, which has auxiliary grooves 26, and the third stator core 21C, which does not have auxiliary grooves 26, in a ratio of LA:LC = 1:9, the 24th-order torque ripple can be reduced compared to when the system is composed solely of the third stator core 21C, which has a larger 24th-order torque ripple per unit volume thickness.

[0063] Furthermore, since the shoe width Wshu is more than twice the thickness of the electromagnetic steel sheet constituting the first stator core 21A, it is generally possible to punch it out using a die, which improves mass production efficiency and reduces manufacturing costs. Furthermore, as in this embodiment, by arranging the auxiliary grooves 26 such that δ1 ≥ 2·δ2, the phase difference of the torque ripple can be increased, as can be seen from Figure 16, thus reducing the torque ripple more effectively. Furthermore, by making the shape of the auxiliary groove 26 semi-circular, the corners of the auxiliary groove 26 are eliminated, which improves the mold life and reduces manufacturing costs.

[0064] In this embodiment, the rotor 4 is of the embedded magnet type, but by changing the pole arc angle β, the torque ripple of the slot harmonic order and lower orders can also be reduced, and the torque ripple of each order can be suppressed in a balanced manner. Furthermore, since the rotor 4 of this embodiment has a double V-shaped structure, there is a high degree of freedom in the arrangement of the magnets, making it easy to bring the magnetic flux density distribution in the air gap 3 closer to a sine wave.

[0065] Next, a modified example of the rotating electric machine 400 of Embodiment 4 will be described. Figure 21 is an enlarged view of the tooth tip portion 23a of the first stator core 21A, which is a modified example of the rotating electric machine according to Embodiment 4. Note that in Figure 21, the relationship between the electrical angles δ1 and δ2 of the auxiliary groove 26 described in Figure 20 is the same. As shown in Figure 21, by increasing the thickness of the shoe 27 on the radial (R) outer circumference side, and making the Wshu more than twice the thickness of the electromagnetic steel sheet constituting the first stator core 21A, it is possible to reduce manufacturing costs while obtaining the effects of torque ripple reduction and torque increase. Furthermore, while Embodiment 4 illustrates a configuration where LA:LC = 1:9, increasing the ratio of LA can further reduce the 24th-order torque ripple. In this case, the torque will be lower than that of Embodiment 4, but it will be higher than that of Embodiment 1, which is composed only of the first stator core 21A.

[0066] Furthermore, in Embodiment 4, the phase difference of the torque ripple was greater than 90 degrees, but if the amplitude is smaller than that of the third stator core 21C, the torque ripple reduction effect of Embodiment 4 can be obtained to some extent even if the phase difference of the torque ripple is 90 degrees or less. Furthermore, although Embodiment 4 illustrates a configuration combining two types of stator cores, the torque ripple reduction effect of Embodiment 4 can also be obtained when a third stator core 21C without auxiliary grooves 26 is combined with two or more types of first stator cores 21A having different auxiliary groove positions. Furthermore, if a third stator core 21C without auxiliary grooves 26 is combined with two types of first stator cores 21A with different auxiliary groove positions, and their phase difference is 120 degrees each, torque ripple can be almost completely suppressed. Furthermore, in Embodiment 4, the auxiliary grooves 26 were arranged such that δ1 ≥ 2·δ2. However, even when this relationship is not satisfied, if the amplitude of the torque ripple of the first stator core 21A with the auxiliary grooves 26 is small, or the phase difference is sufficiently large, the torque ripple, which is an effect of this embodiment, can be reduced.

[0067] Furthermore, although not shown in the figures, the auxiliary groove 26 in Embodiment 4 was semicircular in shape, but regardless of shape, such as a square or triangle, the torque ripple reduction effect of Embodiment 4 can be obtained as long as the structure is cut from the tooth tip 23a toward the outer circumference. Furthermore, although not shown in the figures, the torque ripple reduction effect of this embodiment can be obtained even when the combination of the number of magnetic poles and the number of slots is different, as long as S / P ≥ 3 is satisfied. Furthermore, although not shown in the diagram, even with embedded magnet type rotors that have a different rotor structure, the torque ripple reduction effect of this embodiment can be obtained as long as S / P ≥ 3 is satisfied. Furthermore, because the polar arc angle can be changed, torque ripple of the slot harmonic order and lower orders can also be reduced.

[0068] Furthermore, as in Embodiment 3, by sandwiching the third stator core 21C between the first stator core 21A, which is divided into two parts in the axial direction (or vice versa), and stacking them in the axial direction to create a symmetrical structure, the electromagnetic force applied to the rotor 4 can be balanced regardless of the axial position, thereby reducing vibration and bearing damage. Furthermore, while Embodiment 4 assumes the use of flat rectangular wire, round wire can be used, and the winding slot 24 does not necessarily have to be approximately rectangular in shape.

[0069] As described above, the rotating electric machine of Embodiment 4 can reduce torque ripples by arranging auxiliary grooves at the tip of the teeth, thereby changing the amplitude of torque ripples that are larger than the slot harmonics. Furthermore, it is possible to increase torque.

[0070] Embodiment 5. Embodiment 5 is a modification of the stacking method in Embodiment 4.

[0071] The rotating electric machine of Embodiment 5 will be explained, focusing on the differences from Embodiments 1 and 4, based on Figure 22, a perspective view of the stator core of the rotating electric machine, showing one-eighth of the circumference. In the diagram of Embodiment 5, parts that are the same as or corresponding to those in Embodiment 1 are denoted by the same reference numerals. In order to distinguish it from Embodiment 1, Embodiment 5 is referred to as the rotating electric machine 500.

[0072] The basic configuration of the rotating electric machine according to Embodiment 5 is the same as that of Embodiment 4. However, as shown in Figure 22, when stacking the stator cores 21AC in the axial direction, the first stator core 21A is sandwiched between the third stator core 21C, which is approximately divided into two axial sections within the dimensional tolerance range.

[0073] As shown in Figure 22, by stacking the components in a symmetrical structure along the axial direction, the electromagnetic force applied to the rotor 4 can be balanced regardless of its axial position, thereby reducing vibration and bearing damage. Furthermore, by positioning a third stator core 21C without auxiliary grooves at its axial end, magnetic saturation at the shoe 27 of the stator core 21AC is relatively mitigated compared to the shoe 27 of the first stator core 21A which has auxiliary grooves 26. This reduces the amount of magnetic flux leaking into the winding slot 24 and lowers eddy current losses generated in the coil 25.

[0074] As described above, the rotating electric machine of Embodiment 5 can reduce torque ripples by arranging auxiliary grooves at the tip of the teeth, thereby changing the amplitude of torque ripples that are larger than the slot harmonics. Furthermore, the electromagnetic force applied to the rotor can be balanced.

[0075] Embodiment 6. Embodiment 6 involves dividing the first stator core 21A, which has an auxiliary groove, into two parts and sandwiching it between the third stator core 21C, which does not have an auxiliary groove, and providing a notch in the rotor.

[0076] Regarding the rotating electric machine of Embodiment 6, we will explain the differences from Embodiment 1 based on Figures 23 and 24, which are axial cross-sectional views of the circumferential 1 / 8 of the rotating electric machine; Figure 25, which is a perspective view of the stator core of the rotating electric machine, which is 1 / 8 of the circumferential 1 / 8 of the rotating electric machine; Figure 26, which is axial cross-sectional views of the rotor of the rotating electric machine, which is 1 / 8 of the circumferential 1 / 8 of the rotating electric machine; Figure 27, which is axial cross-sectional views of the circumferential 1 / 8 of the rotating electric machine; Figure 28, which is the analysis result of the 6th to 24th order torque ripple amplitude of the rotating electric machine; Figure 29, which is the analysis result of the 18th order torque ripple amplitude with respect to the position of the auxiliary groove of the rotating electric machine; Figure 30, which is an explanatory diagram of the phase difference of the rotating electric machine; Figure 31, which is the analysis result of the 24th order torque ripple amplitude with respect to the position of the auxiliary groove of the rotating electric machine; and Figure 32, which is an explanatory diagram of the phase difference of the rotating electric machine. In the diagram of Embodiment 6, parts that are the same as or corresponding to those in Embodiment 1 are denoted by the same reference numerals. In order to distinguish it from Embodiment 1, Embodiment 6 is referred to as the rotating electric machines 600, 601, and 602.

[0077] The configuration of the rotating electric machine 600 of Embodiment 6 will be described with reference to Figures 23 to 26. Figure 23 is an axial cross-sectional view of the rotating electric machine 600 at 1 / 8 of the circumferential direction, and the basic configuration of the first stator core 21A of the rotating electric machine 600 is the same as in Figure 1 of Embodiment 1. However, the auxiliary groove 26 is positioned so that the auxiliary groove position is α = 7.0 degrees. In addition, the rotor 4B is provided with a notch 45, which will be explained in detail later in Figure 26. Figure 24 is an axial cross-sectional view of the rotating electric machine 600 at 1 / 8 of the circumferential direction, and the basic configuration of the third stator core 21C of the rotating electric machine 600 is the same as that shown in Figure 5 in Embodiment 1. However, a notch 45 is provided in the rotor 4B. Figure 25 is a perspective view of the stator core of the rotating electric machine 600, showing a circumferential 1 / 8 view. The stator core 21AC of the rotating electric machine 600 is constructed by stacking a first stator core 21A sandwiched between a third stator core 21C, which is divided into two parts in the axial direction, resulting in a symmetrical structure in the axial direction. Furthermore, if the stacking thickness of the first stator core 21A is LA and the stacking thickness of the third stator core 21C is LC, then the configuration is such that LA:LC = 3:2.

[0078] Figure 26 is an axial cross-sectional view of the rotor 4B of the rotating electric machine 600 at a circumferential 1 / 8 distance, and the basic configuration of the rotor 4B of the rotating electric machine 600 is the same as in Figure 4 of Embodiment 1. However, a notch 45 is positioned on the outer circumference of the rotor 4 at a position symmetrical with respect to the d-axis 44. The notch 45 has a notch angle γ, which is the angle between two straight lines connecting the rotation axis of the rotor 4B and the approximate center of the notch 45. If the smaller notch angle is denoted as γ1 and the larger notch angle as γ2, then the notches are positioned such that the relationship with the polar arc angles β1 and β2 is γ1 < β1 < γ2 < β2. In this embodiment, β1 = 65 degrees, β2 = 135 degrees, γ1 = 40 degrees, and γ2 = 105 degrees. In this way, a 3-phase motor with S / P=6 is constructed, meaning that each pole and each phase is 2, resulting in an 8-pole, 48-slot distributed winding motor.

[0079] Next, the effects of the rotating electric machine 600 of Embodiment 6 will be described. Figure 27 is an axial cross-sectional view of one-eighth of the circumferential direction of a rotating electric machine 601 in which there are no auxiliary grooves on the tooth tips 23a of the stator core 21 and no notches on the outer circumference of the rotor core. In other words, the rotating electric machine 601 has no auxiliary grooves on the stator core and no notches on the rotor core.

[0080] Figure 28 shows the 2D-FEM analysis results of the 6th to 24th order torque ripple amplitudes generated in the rotating electric machine 600 of Embodiment 6, the rotating electric machine 602 shown only in Figure 24, and the rotating electric machine 601 shown only in Figure 27. However, the data is normalized using the 24th order torque ripple amplitude generated in Embodiment 6. For the sake of clarity in the comparison, the rotating electric machine consisting only of the stator core and rotor shown in Figure 24 is referred to as the rotating electric machine 602. In other words, the rotating electric machine 602 has no auxiliary grooves on the stator core and a notch on the rotor core. In addition, the rotating electric machine 600 of Embodiment 6 has auxiliary grooves in the stator core and notches in the rotor core.

[0081] Figure 29 shows the 2D-FEM analysis results illustrating the change in the amplitude of the 18th-order torque ripple with respect to the position of the auxiliary groove 26 of the rotating electric machine 600 of Embodiment 6. However, it is normalized using the 18th-order torque ripple generated at the third stator core 21C in Figure 24. Figure 30 shows the phase difference with reference to the phase of the 18th-order torque ripple generated in the third stator core 21C without the auxiliary groove 26 of the rotating electric machine 600 of Embodiment 6. Figure 31 shows the results of a 2D-FEM analysis illustrating the change in the amplitude of the 24th-order torque ripple with respect to the position of the auxiliary groove 26 of the rotating electric machine 600 of Embodiment 6. However, it is normalized using the 24th-order torque ripple generated at the third stator core 21C in Figure 24. Figure 32 shows the phase difference with reference to the phase of the 24th-order torque ripple generated in the third stator core 21C without the auxiliary groove 26 of the rotating electric machine 600 of Embodiment 6.

[0082] To explain the effects of the rotating electric machine 600 of Embodiment 6, we will use the rotating electric machine 601 shown in Figure 27, which is obtained by removing the auxiliary groove 26 from the stator core 21AC and the notch from the rotor 4B of the rotating electric machine 600 according to Embodiment 6. In an 8-pole, 48-slot motor, the slot harmonic order is 12th, resulting in a large 12th-order torque ripple amplitude. Therefore, as shown in Figure 26, slot harmonic components are suppressed by placing notches 45 on the outer circumference of the rotor. As shown in Figure 28, in the rotating electric machine 602 of Figure 24, where a notch 45 is positioned on the outer circumference of the rotor, the amplitude of the 12th-order torque ripple can be reduced to about 1 / 3. On the other hand, the 18th and 24th-order torque ripples, which are higher in order than the slot harmonics, have increased.

[0083] As shown in Figures 29 and 30, when auxiliary grooves 26 are placed on the third stator core 21C in Figure 24, the amplitude and phase of the 18th-order torque ripple change. There are auxiliary groove positions where the amplitude is smaller than that of the third stator core 21C without the auxiliary grooves 26, but there are no auxiliary groove positions where the phase changes by more than 90 degrees. In other words, it is expected that only the torque ripple reduction effect due to the combination of amplitudes can be obtained.

[0084] As shown in Figures 31 and 32, it can be seen that when an auxiliary groove 26 is placed on the third stator core 21C of Figure 24, the amplitude and phase of the 24th-order torque ripple change. The phase changes by more than 90 degrees, and when the auxiliary groove position is 7.0 degrees, the phase difference is approximately 180 degrees, so it is expected that the torque ripple can be reduced more effectively.

[0085] Based on the above, by configuring the rotating electric machine 600 of Embodiment 6, as shown in Figure 28, the 18th-order torque ripple can be suppressed by approximately 20.1% and the 24th-order torque ripple by approximately 88.2% compared to the rotating electric machine with only the third stator core 21C without the auxiliary groove 26 shown in Figure 24.

[0086] Therefore, by combining the first stator core 21A, which has an auxiliary groove, and the third stator core 21C, which does not have an auxiliary groove, in the axial direction, torque ripples with a phase difference greater than 90 degrees can be superimposed, and torque ripples of a higher order than slot harmonics can be effectively suppressed. Furthermore, by using only two types of stator cores 21, the number of stator core types 21 can be minimized, thereby reducing manufacturing costs. Furthermore, by using a third stator core 21C without the auxiliary groove 26, higher torque can be achieved compared to when the system is composed solely of the first stator core 21A which has the auxiliary groove 26.

[0087] Furthermore, by combining the first stator core 21A, which has auxiliary grooves 26, and the third stator core 21C, which does not have auxiliary grooves 26, in a ratio of LA:LC = 3:2, the 18th and 24th order torque ripples can be reduced compared to when the system is composed solely of the stator core 21B, which does not have auxiliary grooves 26 and has a larger torque ripple per unit thickness. Furthermore, by sandwiching the first stator core 21A, which has auxiliary grooves 26, between two third stator cores 21C that are divided axially and lack auxiliary grooves 26, for example, an axially symmetrical structure is achieved. This allows the electromagnetic force applied to the rotor 4 to be balanced regardless of the axial position, thereby reducing vibration and bearing damage. Furthermore, by positioning the third stator core 21C, which lacks the auxiliary groove 26, at the axial end, the magnetic saturation at the shoe 27 of the stator core 21AC is relatively mitigated compared to the shoe 27 of the first stator core 21A, which has the auxiliary groove 26. This reduces the magnetic flux leaking into the winding slot 24 and lowers eddy current losses generated in the coil 25.

[0088] Furthermore, by making the shape of the auxiliary groove 26 semi-circular, the corners of the auxiliary groove 26 are eliminated, which improves the mold life and reduces manufacturing costs.

[0089] In Embodiment 6, the phase difference of the 24th-order torque ripple was greater than 90 degrees. However, if the amplitude is smaller than that of the third stator core 21C, the torque ripple reduction effect of Embodiment 6 can be obtained to some extent even if the phase difference of the torque ripple is 90 degrees or less. Furthermore, while Embodiment 6 illustrates a configuration combining two types of stator cores—one with an auxiliary groove 26 and one without—the torque ripple reduction effect of this embodiment can also be obtained when combining a third stator core 21C without an auxiliary groove with two or more first stator cores 21A having different auxiliary groove positions. Furthermore, if a third stator core 21C without auxiliary grooves 26 is combined with two types of first stator cores 21A having different positions for the auxiliary grooves 26, and their phase difference is 120 degrees each, torque ripple can be suppressed almost completely, similar to this embodiment.

[0090] Furthermore, although not shown in the figures, the auxiliary groove 26 in Embodiment 6 was semicircular in shape, but regardless of shape, such as a square or triangle, the torque ripple reduction effect of this embodiment can be obtained as long as the structure is cut from the tooth tip 23a toward the outer circumference. Furthermore, although not shown in the figures, the torque ripple reduction effect of this embodiment can be obtained even when the combination of the number of magnetic poles and the number of slots is different, as long as S / P ≥ 3 is satisfied.

[0091] Furthermore, although not shown in the diagram, even with embedded magnet type rotors that have a different rotor structure, the torque ripple reduction effect of this embodiment can be obtained as long as S / P ≥ 3 is satisfied. In addition, since the polar arc angle can be changed, torque ripple of the slot harmonic order and lower orders can also be reduced. Furthermore, although the polar arc angles of the rotor 4 exemplified in Embodiment 6 are β1 = 65 degrees and β2 = 135 degrees, the torque ripple reduction effect of this embodiment can be further enhanced if the range is 50 ≤ β1 ≤ 70 and 130 ≤ β2 ≤ 140. Furthermore, while Embodiment 6 assumes the use of flat rectangular wire, round wire can be used, and the winding slot 24 does not necessarily have to be approximately rectangular in shape.

[0092] As described above, the rotating electric machine of Embodiment 6 can reduce torque ripples by changing the amplitude of torque ripples larger than the slot harmonics by arranging auxiliary grooves at the tip of the teeth. Furthermore, by providing notches in the rotor, the slot harmonic component and torque ripples of a higher order than the slot harmonics can be reduced.

[0093] Embodiment 7. Embodiment 7 combines the rotating electric machine described in Embodiments 1 to 6 with a power drive unit that controls the rotating electric machine to form a rotating electric machine system, and mounts this rotating electric machine system on an electric vehicle. The functions required of the power drive unit will also be described.

[0094] The rotating electric machine system 703 and the electric vehicle 700 of Embodiment 7 will be described with reference to Figure 33. In Figure 33, these are shown as the rotating electric machine 701 and the power drive unit 702.

[0095] First, we will explain the functions required of the power drive unit 702 that controls the rotating electric machines 100 to 600 described in Embodiments 1 to 6. Note that the rotating electric machines 100 to 600 will be collectively referred to as the rotating electric machine 701.

[0096] In the distributed-winding motor, which is the rotating electric machine 701 described in Embodiments 1 to 6, a power drive device 702 (also called an inverter) is combined as a control means for controlling the rotation of the motor. In this case, since the distributed-winding motor alone is mainly suitable for reducing higher-order torque ripple, it is desirable to apply a power drive device that performs rotational control mainly to reduce lower-order torque ripple in order to complement the torque ripple reduction effect.

[0097] As such a power drive device, any power drive device and drive control method that perform rotational control to reduce torque ripple, which are known in various forms, may be used. For example, in order to control using a correction signal generation table prepared in advance by calculating a torque compensation signal to cancel out the torque ripple generated in the output torque of the motor, a power drive device equipped with a memory device that stores the data of this table can be used. Furthermore, torque compensation signals and correction signal generation tables can be prepared by calculating the motor's torque ripple and then calculating a sinusoidal current command value that generates a torque in the opposite phase to it. Alternatively, instead of using a pre-calculated and prepared correction signal generation table, the system may be equipped with detection means for detecting motor operation and measurement means for measuring motor torque ripple. Based on the difference between the detection signal (a detection result) and the command signal, and the torque ripple (a measurement result), feedback is used to calculate a control signal that cancels and reduces torque ripple of a desired order.

[0098] Not limited to the methods exemplified above, any known power drive device and drive control method for reducing torque ripple may be applied. Particularly desirable is a combination of the distributed winding motor, power drive unit, and drive control method described above that can complement and cancel out torque ripples of a different order than those canceled out by the distributed winding motor. Specifically, since the distributed winding motors of Embodiments 1 to 6 are mainly effective in reducing 24th-order torque ripple, it is desirable to combine them with a power drive unit and drive control method that reduces torque ripples of lower orders, up to about 6th and 12th order. Furthermore, when combined with distributed winding motors capable of reducing torque ripple to even lower orders, such as the 18th and 12th order, it is advisable to combine them with power drive devices and drive control methods that can complement and cancel out torque ripple of different orders.

[0099] By providing a power drive device and drive control method, which primarily suppress lower-order torque ripple, as a control means for controlling the rotation of the distributed winding motor of Embodiments 1 to 6, it is possible to reduce torque ripple of a higher order than the slot harmonics obtained by the distributed winding motor alone. Furthermore, it becomes possible to reduce torque ripple over a relatively wide bandwidth from the lower-order to the higher-order.

[0100] In particular, by combining a power drive device and drive control method that can complement and cancel out torque ripple of a different order than that canceled out by a distributed winding motor, it becomes possible to reduce torque ripple of each order in a well-balanced manner overall. Furthermore, by combining the rotating electric machine 701 and the power drive unit 702 of Embodiments 1 to 6 to form a rotating electric machine system 703, and mounting this rotating electric machine system 703 on an electric vehicle, since the torque pull of a certain order that is difficult to reduce by motor control is reduced in advance, vibration and magnetic noise can be made extremely small when combined with motor control, and a highly quiet electric vehicle 700 can be obtained.

[0101] As described above, according to Embodiment 7, a rotating electric machine system and an electric vehicle equipped with the rotating electric machine system can be obtained that can reduce torque ripple of a higher order than the slot harmonics, which are often difficult to suppress with motor control.

[0102] Although this application describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but can be applied individually or in various combinations to the embodiments. Accordingly, countless variations not illustrated are conceivable within the scope of the art disclosed herein. These include, for example, modifying, adding or omitting at least one component, or even extracting at least one component and combining it with components of other embodiments. [Explanation of Symbols]

[0103] 2 Stator, 2A First stator, 2B Second stator, 2C Third stator, 3 Air gap, 4, 4B Rotor, 21, 21AB, 21AC Stator core, 21A First stator core, 21B Second stator core, 21C Third stator core, 22 Core back, 23 Teeth, 23A First tooth, 23B Second tooth, 23C Third tooth, 23a Tooth tip, 23b Tooth extension, 23c Teeth central shaft, 24 winding slots, 25 coil, 26, 26s, 26t auxiliary grooves, 27 shoe, 41 rotor core, 42 magnet slot, 42f first layer magnet slot, 42s second layer magnet slot, 42t third layer magnet slot, 43 permanent magnet, 43f 1st layer permanent magnet, 43s; 2nd layer permanent magnet, 43t; 3rd layer permanent magnet, 45; Notches, 100, 101, 102, 103, 104, 200, 201, 300, 400, 500, 600, 601, 602, 701; Rotating electric machine, 700; Electric vehicle, 702; Power drive unit, 703; Rotating electric machine system.

Claims

1. A rotor having multiple permanent magnet poles, The stator comprises an annular core back and a stator core having a plurality of teeth facing the circumferential surface of the rotor, which are stacked in the axial direction of the rotor. A rotating electric machine having a winding slot for winding wire between the aforementioned teeth and the adjacent teeth, Multiple auxiliary grooves extending in the stacking direction are arranged on the surface of the tooth tip of the tooth facing the rotor. If P is the number of magnetic poles of the rotor and S is the number of winding slots, then S / P ≥ 3. If the fundamental wave component of the current frequency driving the aforementioned rotating electric machine is taken as the first order, and n is a natural number, and the order of the torque ripple being reduced is 6n, then 6n > 2S / P is satisfied. The stator is constructed using a combination of multiple stator cores, each having a different position of the auxiliary groove at the tip of the teeth, resulting in a smaller 6n-th order torque ripple per unit thickness than the 6n-th order torque ripple when the stator is constructed using only one type of stator core, each having the maximum 6n-th order torque ripple per unit thickness. Rotating electric machine.

2. A rotor having magnetic poles of multiple permanent magnets, The stator comprises an annular core back and a stator core having a plurality of teeth facing the circumferential surface of the rotor, which are stacked in the axial direction of the rotor. A rotating electric machine having a winding slot for winding wire between the aforementioned teeth and the adjacent teeth, Multiple auxiliary grooves extending in the stacking direction are arranged on the surface of the tooth tip of the tooth facing the rotor. If P is the number of magnetic poles of the rotor and S is the number of winding slots, then S / P ≥ 3. The stator further comprises a stator core having teeth without the aforementioned auxiliary grooves, If the fundamental wave component of the current frequency driving the aforementioned rotating electric machine is taken as the first order, and n is a natural number, and the order of the torque ripple being reduced is 6n, then 6n > 2S / P is satisfied. The 6n-th order torque ripple is greater than the 6n-th order torque ripple when the stator is constructed using only one type of stator core, which has the maximum 6n-th order torque ripple per unit thickness. The stator cores are assembled in the axial direction in such a ratio that the stacking thickness of the stator cores is small when the stator cores having the auxiliary grooves arranged at the tip of the teeth and the stator cores without the auxiliary grooves at the tip of the teeth are combined, resulting in a smaller 6n-th order torque ripple. Rotating electric machine.

3. A rotor having magnetic poles of multiple permanent magnets, The stator comprises an annular core back and a stator core having a plurality of teeth facing the circumferential surface of the rotor, which are stacked in the axial direction of the rotor. A rotating electric machine having a winding slot for winding wire between the aforementioned teeth and the adjacent teeth, Multiple auxiliary grooves extending in the stacking direction are arranged on the surface of the tooth tip of the tooth facing the rotor. If P is the number of magnetic poles of the rotor and S is the number of winding slots, then S / P ≥ 3. The width of the narrowest part of the shoe, which is the circumferentially extended portion of the tooth tip, is at least twice the thickness of the electromagnetic steel sheet constituting the stator core. Rotating electric machine.

4. A rotor having magnetic poles of multiple permanent magnets, The stator comprises an annular core back and a stator core having a plurality of teeth facing the circumferential surface of the rotor, which are stacked in the axial direction of the rotor. A rotating electric machine having a winding slot for winding wire between the aforementioned teeth and the adjacent teeth, Multiple auxiliary grooves extending in the stacking direction are arranged on the surface of the tooth tip of the tooth facing the rotor. If P is the number of magnetic poles of the rotor and S is the number of winding slots, then S / P ≥ 3. If the tip of the tooth is divided by the auxiliary groove, and the electrical angle of the tip on the circumferential center side of the tip of the tooth is δ1, and the electrical angles of the tip on each end side in the circumferential direction are δ2, then δ1 ≥ 2δ2. Rotating electric machine.

5. The rotating electric machine according to any one of claims 1 to 4, wherein the winding is wound in a distributed winding and satisfies S / P ≥ 6.

6. The rotating electric machine according to any one of claims 1 to 4, wherein one auxiliary groove is arranged on the tip of each tooth at a position symmetrical to the circumferential center point of the tip of the tooth.

7. The rotating electric machine according to any one of claims 1 to 4, wherein the shape of the auxiliary groove is semicircular.

8. The rotor has an embedded magnet structure, according to any one of claims 1 to 4.

9. The rotor is provided with a pair of first-layer magnet slots and a pair of second-layer magnet slots arranged in a V-shape, with the d-axis of the rotor core, which is the main direction of the magnetic flux created by the magnetic poles, having a radial distance narrower on the inner side than on the radially outer side. The rotating electric machine according to any one of claims 1 to 4, wherein each magnet slot has a permanent magnet inserted that is magnetized in parallel in the short-side direction.

10. The rotor is provided with a pair of first-layer magnet slots, a pair of second-layer magnet slots, and a pair of third-layer magnet slots, each arranged in a V-shape with the radially inward distance being narrower than the radially outward distance, centered on the d-axis of the rotor core, which is the main direction of the magnetic flux created by the magnetic poles. The rotating electric machine according to any one of claims 1 to 4, wherein each magnet slot has a permanent magnet inserted that is magnetized in parallel in the short-side direction.

11. The rotating electric machine according to any one of claims 1 to 4, wherein the winding is composed of flat rectangular wire.

12. The rotating electric machine according to claim 1, wherein the stator is constructed by stacking multiple types of stator cores, each having a different position of the auxiliary groove at the tip of the teeth, in a structure that is symmetrical in the axial direction.

13. The rotating electric machine according to claim 2, wherein the stator core without the auxiliary groove is arranged at the axial end of the stator.

14. The rotating electric machine according to claim 13, wherein a notch extending in the axial direction of the rotor is arranged on the outer circumference of the rotor.

15. A rotating electric machine system comprising a rotating electric machine according to any one of claims 1 to 4 and a power drive device that controls the rotation of the rotating electric machine and suppresses torque ripple of the rotating electric machine.

16. An electric vehicle equipped with the rotating electric machine system of claim 15.

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