Rotating electric machine

Abstract

The invention relates to a rotating electric machine comprising a stator and a rotor. On the stator iron core of the stator, the ends of the teeth define the openings of the slots through which the armature windings of different phases conduct, which have two beveled edges at the two ends of the inner circumferential face which are partially removed circumferentially. The rotor iron core of the rotor has grooves whose outer circumferential face is concave along the central axis. Each of these grooves produces a waveform in which the concave parts are located on either side of the convex part in the direction of rotor rotation, and the first groove is located on the leading side in the direction of rotation and the second groove is located on the rear side in the direction of rotation. The first and second grooves are asymmetrical with respect to the axis d.

Description

Rotating electric machines

[0001] An embodiment of the present invention relates to a rotating electric machine.

[0002] For example, permanent magnet synchronous motors (PMSMs) are rotating electrical machines used to drive vehicles such as automobiles and railway cars, and many of them are of the interior permanent magnet synchronous motor (IPMSM) type, in which permanent magnets are embedded in the rotor core.

[0003] An IPMSM includes a stator with an armature winding (coil) wound around a stator core, and a rotor that is rotatable relative to the stator and has permanent magnets embedded in slots in the rotor core. In an IPMSM, when a desired current flows through the armature winding, magnetic flux is generated in the armature winding. The rotor rotates due to magnetic attraction and repulsion between this magnetic flux and the permanent magnets.

[0004] In rotating electrical machines such as IPMSMs, harmonics appear in the rotational torque and electromagnetic force depending on the combination of the number of magnetic poles and slots in the rotor. For example, in rotating electrical machines with 8 poles and 48 slots, which are often used as automotive motors, it is not uncommon for harmonics of the sixth electrical order and integer multiples thereof to occur. These harmonics often cause vibration and noise, and it is necessary to appropriately suppress them.

[0005] Japanese Patent No. 6075034 Japanese Patent No. 5073805 Japanese Patent Laid-Open No. 2013-106496

[0006] The present invention has been made in light of this, and its object is to provide a rotating electric machine that can suppress harmonics of electromagnetic force at a targeted operating point and reduce vibration and noise.

[0007] According to an embodiment, a rotating electric machine includes a stator and a rotor. The stator has a cylindrical stator core with teeth and slots alternately arranged in the circumferential direction, and multi-phase armature windings wound around the teeth through the slots. The rotor has a rotor core with multiple magnetic poles arranged along an outer circumferential surface facing the inner circumferential surface of the stator core with a gap therebetween, and multiple permanent magnets provided on each of the magnetic poles, and is rotatable around a central axis concentric with the stator core. In the stator core, the tips of the teeth that define the edges of the openings of the slots on the inner circumferential surface between the slots through which the armature windings of different phases pass have a pair of chamfers missing from both ends of the circumferential surface. In a cross section of the rotor core perpendicular to the central axis, in a cross section state in which a groove shape on the outer peripheral surface described below is not provided, an axis extending radially through the circumferential ends of the magnetic poles and the central axis is defined as a q-axis, and an axis electrically spaced 90 degrees circumferentially from the q-axis is defined as a d-axis. In each of the magnetic poles, the rotor core has a plurality of grooves recessed in the outer peripheral surface along the central axis, each groove forming a wave shape with recesses on both sides of a protrusion aligned along the direction of rotation, and has a first groove portion located on the leading side of the d-axis in the direction of rotation and a second groove portion located on the trailing side of the d-axis in the direction of rotation between the q-axis passing through both circumferential ends of the magnetic poles. The first groove portion and the second groove portion are asymmetric with respect to the d-axis.

[0008] 1 is a cross-sectional view of a permanent magnet type rotating electric machine according to an embodiment; FIG. 2 is a cross-sectional view showing an enlarged portion of the stator core of the stator and the rotor core of the rotor in the rotating electric machine shown in FIG. 1; FIG. 3 is an enlarged view of the grooves (first groove portion and second groove portion) shown in FIGS. 1 and 2; FIG. 4 is an enlarged view of the vicinity of the tip of the tooth shown in FIG. 2, as a form of the tip of the tooth of the stator core; FIG. 5 is a diagram showing the relationship between the circumferential length of a pair of chamfers, which are missing portions of the tooth, and the electromagnetic force ratio; FIG. 6 is a diagram showing the relationship between the area ratio of a pair of chamfers, which are missing portions of the tooth, and the electromagnetic force ratio; FIG. 7 is an enlarged view of the arrangement of the first groove portion and the second groove portion shown in FIGS. 1 and 2; FIG. 8 is a diagram showing the relationship between the electrical angle (θLP1) in the first groove portion and the electromagnetic force ratio; FIG. 9 is a diagram showing the relationship between the electrical angle (θLP2) in the first groove portion and the electromagnetic force ratio; FIG. 10 is a diagram showing the relationship between a first range (θLW) and the electromagnetic force ratio; and FIG. 11 is a diagram showing the relationship between the electrical angle (θRP1) in the second groove portion and the electromagnetic force ratio. FIG. 1 is a diagram showing the relationship between the electrical angle (θRP2) in the second groove and the electromagnetic force ratio. FIG. 2 is a diagram showing the relationship between the second range (θRW) and the electromagnetic force ratio. FIG. 3 is a diagram showing the relationship between the difference in depth of two recesses in the first groove and the electromagnetic force ratio. FIG. 4 is a diagram showing the relationship between the difference in depth of two recesses in the second groove and the electromagnetic force ratio. FIG. 5 is a diagram showing a comparative example (A) in which the groove configuration of the rotor core is different from that of the present invention. FIG. 6 is a diagram showing a comparative example (B) in which the groove configuration of the rotor core is different from that of the present invention. FIG. 7 is a diagram showing a comparative example (C) in which the groove configuration of the rotor core is different from that of the present invention. FIG. 8 is a diagram showing a comparative example (E) in which the groove configuration of the rotor core is different from that of the present invention. FIG. 9 is a diagram showing the electromagnetic force ratio in each comparative example as a ratio when the present invention is set to 0.

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that common components throughout the embodiments are designated by the same reference numerals, and redundant explanations will be omitted. Each figure is a schematic diagram for facilitating understanding of the embodiment, and the shape, dimensions, ratios, etc. may differ from those of an actual device. However, these may be appropriately modified in design, taking into consideration the following explanation and known techniques.

[0010] 1 is a cross-sectional view of a permanent magnet type rotating electric machine according to an embodiment, specifically a transverse cross-sectional view taken along a plane perpendicular to the central axis of the rotating electric machine. The rotating electric machine is used, for example, as a drive motor or generator in a hybrid electric vehicle (HEV) or an electric vehicle (EV). However, the use of the rotating electric machine is not limited to this, and it can also be used for other purposes.

[0011] As shown in Fig. 1, the rotating electric machine 10 is configured as, for example, an inner rotor type rotating electric machine. The rotating electric machine 10 includes an annular or cylindrical stator 12 supported by a fixed frame (not shown), and a rotor 14 supported concentrically with the stator 12 and rotatable about a central axis CL inside the stator 12. In the following description, the direction along the central axis CL when the rotor 14 rotates in the rotating electric machine 10 is referred to as the axial direction, and the direction in which the rotor 14 rotates about the central axis CL is referred to as the circumferential direction. The direction perpendicular to the axial and circumferential directions is referred to as the radial direction, and the side closer to the central axis CL in the radial direction is referred to as the inner side, and the side away from the central axis CL is referred to as the outer side.

[0012] The stator 12 includes a cylindrical stator core 16 and an armature winding (coil) 18 wound around the stator core 16. The stator core 16 is formed by concentrically stacking a number of annular electromagnetic steel sheets made of a magnetic material, such as silicon steel. The stator core 16 has a plurality of slots 20 and a plurality of teeth 21. The slots 20 are arranged at approximately equal intervals in the circumferential direction. Each slot 20 opens into the inner peripheral surface of the stator core 16 and extends radially (in the radial direction) from the inner peripheral surface. Each slot 20 is continuous over the entire axial length of the stator core 16. By forming the plurality of slots 20, a plurality of teeth 21 (48 in this embodiment, for example) facing the rotor 14 are formed on the inner peripheral portion of the stator core 16 between adjacent slots 20 in the circumferential direction. In other words, each gap between circumferentially adjacent teeth 21 is configured as a slot 20. As a result, the teeth 21 and the slots 20 are arranged alternately in the circumferential direction. The armature windings 18 are wound around the teeth 21 through the slots 20. The armature windings 18 correspond to multiple phases, for example, three phases: U-phase, V-phase, and W-phase. In this embodiment, the armature windings 18 of the same phase each pass through two circumferentially adjacent slots 20, and the slots 20 corresponding to the U-phase, V-phase, and W-phase are lined up in order in the circumferential direction. By passing a current through the armature windings 18, a predetermined interlinkage magnetic flux is formed in the stator 12, specifically in the teeth 21.

[0013] The rotor 14 is supported at both axial ends by bearings (not shown) and is rotatable together with the shaft (rotating shaft) 22 about the central axis CL. Therefore, the rotor 14 is arranged concentrically with the stator 12, with the outer circumferential surface facing the inner circumferential surface of the stator 12 with a slight gap between them. In this embodiment, the rotor 14 rotates in the direction indicated by the arrow A14 in FIG. 1 .

[0014] The rotor 14 includes a rotor core 24 and permanent magnets 26. The rotor core 24 is generally cylindrical and has an inner bore 25 concentric with the central axis CL. The shaft 22 is inserted into and fitted into the inner bore 25, extending concentrically with the rotor core 24. The inner bore 25 is a hole for fitting the shaft 22 and securing it to the rotor 14. The rotor core 24 is formed by concentrically stacking multiple annular electromagnetic steel plates made of a magnetic material, such as silicon steel, and has multiple magnetic poles (eight poles in this embodiment, for example). The number of magnetic poles is not particularly limited. Each magnetic pole is aligned along the outer circumferential surface 24a of the rotor core 24 and faces the inner circumferential surface 16a of the stator core 16 with a gap therebetween. Each permanent magnet 26 is provided on a magnetic pole of the rotor core 24.

[0015] Here, the q-axis and d-axis are defined as follows in a cross section of the rotor core 24 perpendicular to the central axis CL as shown in FIG. 1 . Note that the cross section of the rotor core 24 is a cross section in a state where grooves 50 (first grooves 51 and second grooves 52) described later are not provided on the outer peripheral surface 24a. The q-axis is an axis extending radially (radially) through the circumferential ends of the magnetic poles of the rotor core 24 and the central axis CL. The d-axis is an axis electrically spaced 90 degrees from the q-axis in the circumferential direction. Here, the direction in which the interlinkage magnetic flux formed by the stator 12 easily flows is referred to as the q-axis. The d-axis and q-axis are arranged alternately around the circumference of the rotor core 24 and at a predetermined phase. One magnetic pole of the rotor core 24 is the region between the q-axes (a circumferential angle region of 1 / 8 of the circumference). Therefore, the rotor core 24 is configured with eight poles (magnetic poles). The circumferential center of one magnetic pole is the d-axis.

[0016] As shown in Fig. 1, two permanent magnets 26 are embedded in the rotor core 24 for each magnetic pole. Magnet embedding holes (hereinafter referred to as embedding holes) 34 having shapes corresponding to the shapes of the permanent magnets 26 are formed on both sides of each d-axis in the circumferential direction of the rotor core 24. The two permanent magnets 26 are respectively loaded and arranged in the embedding holes 34. The permanent magnets 26 may be fixed to the rotor core 24 by, for example, an adhesive or the like.

[0017] Each embedment hole 34 penetrates the rotor core 24 over its entire axial length. Each embedment hole 34 has a generally trapezoidal opening shape and is inclined relative to the d-axis. When viewed in a cross section of the rotor core 24 perpendicular to the center axis CL as shown in FIG. 1 , two embedment holes 34 are arranged side by side, for example, in a generally V-shape. That is, the inner ends of the two embedment holes 34 are adjacent to the d-axis and face each other with a small gap between them. A narrow magnetic path narrow section (bridge section) 36 is formed between the inner ends of the two embedment holes 34 in the rotor core 24. The outer ends of the two embedment holes 34 are spaced from the d-axis along the circumferential direction of the rotor core 24 and are located near the outer circumferential surface 24a of the rotor core 24 and near the q-axis. As a result, the outer end of one embedment hole 34 faces the outer end of the embedment hole 34 of the adjacent magnetic pole across the q-axis. In the rotor core 24, a narrow magnetic path narrow portion (bridge portion) 38 is formed between the outer peripheral end of each embedding hole 34 and the outer peripheral surface 24a of the rotor core 24. In this way, the two embedding holes 34 are arranged so that the distance from the d-axis gradually increases from the inner peripheral end to the outer peripheral end.

[0018] The permanent magnets 26 are loaded into each embedding hole 34 and embedded in the rotor core 24. For example, as shown in FIG. 1 , the permanent magnets 26 are formed as elongated flat plates with a rectangular cross section, and have a first surface (front surface) and a second surface (back surface) that are parallel and opposed to each other, and a pair of side surfaces that are opposed to each other. The permanent magnets 26 have a length that is approximately equal to the entire axial length of the rotor core 24. The permanent magnets 26 may be formed by combining multiple magnets that are divided in the axial direction (longitudinal direction). In this case, the total length of the multiple magnets is formed so that it is approximately equal to the entire axial length of the rotor core 24. Each permanent magnet 26 is embedded over approximately the entire axial length of the rotor core 24. The magnetization direction of the permanent magnets 26 is perpendicular to the first and second surfaces of the permanent magnets 26.

[0019] In the rotor core 24, two permanent magnets 26 located on either side of each d-axis, i.e., two permanent magnets 26 constituting one magnetic pole, are arranged so that their magnetization directions are the same. Furthermore, two permanent magnets 26 located on either side of each q-axis are arranged so that their magnetization directions are opposite. By arranging the multiple permanent magnets 26 in this manner, the area on each d-axis on the outer periphery of the rotor core 24 is formed around one magnetic pole, and the area on each q-axis is formed around an inter-pole space. In this embodiment, the rotating electric machine 10 is configured as a permanent magnet-embedded rotating electric machine with eight poles (four pole pairs) and 48 slots, with the north and south poles of the permanent magnets 26 alternately positioned on the front and back of each adjacent magnetic pole, and wound using distributed winding.

[0020] As shown in FIG. 1 , the rotor core 24 has a plurality of air gap holes (hollow portions) 30. The air gap holes 30 penetrate the rotor core 24 over the entire axial length. The air gap holes 30 are located approximately in the radial center of the rotor core 24 on the q axis, and are provided between two embedded holes 34 of adjacent magnetic poles. In the example shown in FIG. 1 , the air gap holes 30 have a substantially circular cross-sectional shape. The air gap holes 30 function as flux barriers that make it difficult for magnetic flux to pass through, and regulate the flow of interlinkage magnetic flux in the stator 12 and the flow of magnetic flux in the permanent magnets 26. Furthermore, by forming the air gap holes 30, the weight of the rotor core 24 can be reduced.

[0021] 1 and 2, in this embodiment, the teeth 21 of the stator core 16 have a plurality of chamfers 40, and the rotor core 24 has a plurality of grooves 50. These chamfers 40 and grooves 50 will be described below. Fig. 2 is a cross-sectional view showing an enlarged portion of the stator core 16 of the stator 12 and the rotor core 24 of the rotor 14 in the rotating electric machine 10 shown in Fig. 1.

[0022] The chamfers 40 are formed by removing a portion of both circumferential ends of the inner peripheral surface of the tip portions 23 of the teeth 21, and are arranged in pairs in the circumferential direction. The pair of chamfers 40 are symmetrical with respect to the bisector of the maximum circumferential width (W2) of the tip portions 23, which will be described later. The tip portions 23 define the inner peripheral surface 16a of the stator core 16, and also define the edges of the openings 20a of the slots 20 on the inner peripheral surface 16a. In the example shown in Fig. 2, the tip portions 23 protrude further inward than the inner peripheral ends 18a of the armature windings 18 that pass through the slots 20 and are wound around the teeth 21, and hold the inner peripheral ends 18a in place.

[0023] Among the tip portions 23 of the plurality of teeth 21, the tip portions 23 of the teeth 21 that define the edges of the openings 20 a of the slots 20 between the slots 20 through which the armature windings 18 of different phases pass have chamfers 40. In contrast, the tip portions 23 of the teeth 21 that define the edges of the openings 20 a of the slots 20 between the slots 20 through which the armature windings 18 of the same phase pass do not have chamfers 40.

[0024] In the example shown in FIG. 2 , the teeth 21a define the edges of the openings 20a of the slots 20w and 20v, respectively, between the slot 20w through which the W-phase armature winding 18w passes and the slot 20v through which the V-phase armature winding 18v passes. The teeth 21c define the edges of the openings 20a of the slots 20v and 20u, respectively, between the slot 20v through which the V-phase armature winding 18v passes and the slot 20u through which the U-phase armature winding 18u passes. Therefore, the tip portions 23a and 23c of the teeth 21a and 21c each have a chamfer 40. In contrast, the teeth 21b define the edges of the openings 20a of the slots 20v and 20v, respectively, between the slots 20v through which the V-phase armature winding 18v passes. Therefore, the tip portions 23b of the teeth 21b do not have a chamfer 40. As a result, the stator cores 16 are arranged alternately with respect to the plurality of teeth 21 that are arranged at approximately equal intervals in the circumferential direction. In other words, the stator cores 16 are arranged alternately with respect to every other tooth 21.

[0025] The grooves 50 are recessed portions of the outer peripheral surface 24a along the central axis CL in each magnetic pole of the rotor core 24, and are continuous over the entire axial length of the rotor core 24. Each magnetic pole is a region between two adjacent q-axes in the circumferential direction of the rotor core 24, i.e., in the rotation direction of the rotor 14 (the direction indicated by the arrow A14 in FIG. 1 , hereinafter referred to as the rotation direction A14). In this embodiment, the rotor 14 rotates in one direction indicated by the rotation direction A14, and rotation in the opposite direction is not assumed. The grooves 50 have a first groove portion 51 and a second groove portion 52. That is, the grooves 50 in each magnetic pole of the rotor core 24 are composed of the first groove portion 51 and the second groove portion 52. The first groove portion 51 is the groove 50 located on the leading side of the rotation direction A14 with respect to the d-axis, between the q-axes passing through both ends of the circumferential direction of the magnetic pole. The second groove portion 52 is a groove 50 that is arranged on the trailing side of the rotation direction A14 with respect to the d axis, between the q axes that pass through both circumferential ends of the magnetic pole in each magnetic pole. Note that the d axis refers to the d axis that is located between the q axes that pass through both circumferential ends of the magnetic pole in each magnetic pole of the rotor core 24. In the example shown in Figure 2, the groove 50 that is arranged on the left side, which is the leading side in the rotation direction A14, is the first groove portion 51, and the groove 50 that is arranged on the right side, which is the trailing side, is the second groove portion 52.

[0026] The first groove portion 51 and the second groove portion 52 form a wave shape in which recesses 54, 55 are arranged on both sides of a protrusion 53 in the rotational direction A14, or more specifically, in the circumferential direction. That is, the recesses 54, protrusions 53, and recesses 55 are continuous in the rotational direction A14, forming the wave shapes of the first groove portion 51 and the second groove portion 52, respectively.

[0027] The first groove portion 51 and the second groove portion 52 are asymmetric with respect to the d axis. In the example shown in Fig. 2, the first groove portion 51 and the second groove portion 52 have different waveforms and are located at different circumferential positions, which makes them asymmetric with respect to the d axis.

[0028] FIG. 3 is an enlarged view of the first groove portion 51 and the second groove portion 52 shown in FIGS. 1 and 2 . As shown in FIG. 3 , in the first groove portion 51, the maximum distance D541 from one recess 541 of the two recesses 54, 55 closer to the d-axis to the circumscribing circle CO tangent to the outer peripheral surface 24a of the rotor core 24 is greater than the maximum distance D551 from the other recess 551 to the circumscribing circle CO. The maximum distances D541, D551 are the distances from the deepest parts of the recesses 541, 551 to the circumscribing circle CO, and are the distances on a straight line that passes through the deepest parts and is perpendicular to the tangent to the circumscribing circle CO. The convex portion 531 is located inside the circumscribing circle CO. In other words, the top of the convex portion 531 does not contact the circumscribing circle CO. In the second groove portion 52, the maximum distance D552 from one of the two recesses 54, 55 closer to the d-axis to the circumscribing circle CO is greater than the maximum distance D542 from the other recess 542 to the circumscribing circle CO. The maximum distances D552, D542 are the distances from the deepest parts of the recesses 552, 542 to the circumscribing circle CO, and are the distances on a straight line that passes through the deepest parts and is perpendicular to the tangent to the circumscribing circle CO. The convex portion 532 is disposed inside the circumscribing circle CO. In other words, the apex of the convex portion 532 does not contact the circumscribing circle CO.

[0029] As described above, the rotating electric machine 10 according to this embodiment has both the chamfers 40 and the grooves 50 (the first groove portions 51 and the second groove portions 52). Assuming that the rotating electric machine 10 has both the chamfers 40 and the grooves 50, the optimal aspects of the chamfers 40 and the grooves 50 will be described below.

[0030] First, the optimal form of the chamfer 40 on the teeth 21 will be described with reference to Fig. 4. Fig. 4 is an enlarged view showing the vicinity of the tip portions 23b and 23c of the teeth 21b and 21c shown in Fig. 2, as an example of the shape of the tip portions 23 of the teeth 21. The tooth 21c is an example of a tooth 21 having the chamfer 40, and the tooth 21b is an example of a tooth 21 not having the chamfer 40. Note that the shape of the teeth 21 other than the tooth 21c having the chamfer 40 (e.g., the tooth 21a) is the same as the tooth 21c. Furthermore, the shape of the teeth 21 other than the tooth 21b not having the chamfer 40 is the same as the tooth 21b.

[0031] As shown in Figure 4, the maximum circumferential width of the teeth 21b, 21c is W1, and the maximum circumferential width of the tip ends 23b, 23c is W2. The circumferential width is the face-to-face distance on the teeth 21 in a direction perpendicular to the axial and radial directions. The maximum circumferential width (W1) of the teeth 21b, 21c is the maximum circumferential width of the portions of the teeth 21b, 21c other than the tip ends 23b, 23c. In this embodiment, the maximum circumferential width (W2) of the tip ends 23b, 23c of the teeth 21b, 21c is greater than the maximum circumferential width (W1) of the teeth 21b, 21c (W1 < W2).

[0032] Additionally, for each tooth 21c, the radial length of each chamfer 40 is L1 and the circumferential length is L2. The planar shape of each chamfer 40 as viewed from the direction of the central axis CL is a substantially triangular shape defined by a side of length L1 and a side of length L2.

[0033] For teeth 21b without chamfers 40, the area of ​​the tip portion 23b as viewed from the direction of the central axis CL (axial direction) (hereinafter referred to as tip area) is defined as S. The tip area (S) is the area enclosed by arcs S1 and S2 and two linear sides S3 and S4. Arc S1 defines the inner circumferential surface 16a of the stator core 16. Arc S2 is parallel to arc S1 and defines the boundary between the area where the tip portion 23b has the maximum circumferential width (W2) and the remaining area. Two sides S3 and S4 define the edges of the openings 20a of the slots 20 on the inner circumferential surface 16a. For teeth 21c with chamfers 40, the area of ​​the chamfers 40 as viewed from the axial direction is defined as Ac. This area (Ac) is the area of ​​a substantially triangular shape defined by sides of length L1 and L2, and is roughly calculated as L1 × L2 / 2. Therefore, the total area of ​​the pair of chamfers 40 as viewed from the axial direction (hereinafter referred to as the missing area) is twice the area of ​​the chamfer 40 (Ac×2).

[0034] FIG. 5 illustrates the relationship between the circumferential length (hereinafter referred to as the circumferential ratio) of a pair of chamfers 40, which are missing portions of the teeth 21, and the electromagnetic force ratio. The circumferential ratio is the ratio (L2×2 / W2) of the total circumferential length (L2×2) of the pair of chamfers 40 to the maximum circumferential width (W2) of the tip end 23 of the tooth 21 having the chamfers 40. The electromagnetic force ratio is an index indicating the total ratio (%) of the exceedance rates of the electromagnetic forces of six order components, i.e., the sixth, twelfth, and twenty-fourth electrical orders in the radial direction and the sixth, twelfth, and twenty-fourth electrical orders in the circumferential direction, when the allowable range is set to zero in the rotating electric machine 10. The electromagnetic force ratio here is an index for when the circumferential ratio of the chamfers 40 is changed in the rotating electric machine 10 having the chamfers 40 and the grooves 50 (first groove portion 51 and second groove portion 52). If the electromagnetic force ratio is 0%, it indicates that the exceedance rates of the electromagnetic forces of the six order components are within the allowable range.

[0035] As shown in Fig. 5, when the circumferential ratio is less than 42% or more than 89%, the electromagnetic force ratio tends not to be 0%. Therefore, the circumferential ratio of the chamfer 40 is preferably 42% or more and 89% or less (0.42 ≤ L2 × 2 / W2 ≤ 0.89). For this reason, in this embodiment, the circumferential ratio of the chamfer 40 is set to be within the above range (0.42 ≤ L2 × 2 / W2 ≤ 0.89).

[0036] Fig. 6 is a diagram showing the relationship between the area ratio of a pair of chamfers 40, which are missing portions of teeth 21, and the electromagnetic force ratio. The area ratio is the ratio (Ac x 2 / S) of the missing area (Ac x 2) to the tip area (S), and is shown as the missing ratio in Fig. 6. The electromagnetic force ratio conforms to the index shown in Fig. 5. However, the electromagnetic force ratio here is an index when the area ratio of chamfers 40 is changed in a rotating electric machine 10 having chamfers 40 and grooves 50 (first groove portion 51 and second groove portion 52).

[0037] As shown in Fig. 6, when the area ratio of the pair of chamfers 40 is less than 5% or more than 13%, the electromagnetic force ratio tends not to be 0%. Therefore, it is preferable that the ratio of the missing area (Ac x 2) to the tip area (S) is 5% or more and 13% or less (0.05 ≤ Ac x 2 / S ≤ 0.13). For this reason, in this embodiment, the missing area ratio is set to be within the above range (0.05 ≤ Ac x 2 / S ≤ 0.13).

[0038] Next, the arrangement of the first groove portion 51 and the second groove portion 52 in the groove 50 will be described. Fig. 7 is an enlarged view showing the arrangement of the first groove portion 51 and the second groove portion 52 shown in Figs. 1 and 2.

[0039] As shown in FIG. 7 , the first groove portion 51 is disposed within a first electrical angle range θLW relative to the d-axis. The first range θLW is a range of electrical angles calculated by the difference between the electrical angles θLP2 and θLP1. The electrical angle θLP1 is a lower limit value defining the first range θLW, and the electrical angle θLP2 is an upper limit value defining the first range θLW. The electrical angle θLP1 is an electrical angle that indicates the position of the trailing groove end of the first groove portion 51 in the direction of rotation A14 and is the electrical angle, relative to the d-axis, of a continuous portion P541 between the recessed portion 541 and the outer circumferential surface 24a of the rotor core 24. The electrical angle θLP2 is an electrical angle that indicates the position of the leading groove end of the first groove portion 51 in the direction of rotation A14 and is the electrical angle, relative to the d-axis, of a continuous portion P551 between the recessed portion 551 and the outer circumferential surface 24a of the rotor core 24.

[0040] As shown in FIG. 7 , the second grooves 52 are arranged within a second electrical angle range θRW relative to the d-axis. The second range θRW is a range of electrical angles calculated as the difference between the electrical angles θRP2 and θRP1. The electrical angle θRP1 is a lower limit value defining the second range θRW, and the electrical angle θRP2 is an upper limit value defining the second range θRW. The electrical angle θRP1 is an electrical angle that indicates the position of the leading groove end of the second grooves 52 in the direction of rotation A14, and is the electrical angle, relative to the d-axis, of a continuous portion P552 between the recessed portion 552 and the outer circumferential surface 24a of the rotor core 24. The electrical angle θRP2 is an electrical angle that indicates the position of the trailing groove end of the second grooves 52 in the direction of rotation A14, and is the electrical angle, relative to the d-axis, of a continuous portion P542 between the recessed portion 542 and the outer circumferential surface 24a of the rotor core 24.

[0041] FIG. 8 illustrates the relationship between the electrical angle θLP1 in the first groove portion 51 and the electromagnetic force ratio. The electrical angle θLP1 is shown in FIG. 8 as the lower limit of the groove (e.g., electrical degree). The electromagnetic force ratio corresponds to the index shown in FIG. 5 . However, the electromagnetic force ratio here is an index for a rotating electric machine 10 having chamfers 40 and grooves 50 (first groove portion 51 and second groove portion 52) when the electrical angle θLP1 in the first groove portion 51 is changed. As shown in FIG. 8 , when the electrical angle θLP1 exceeds approximately 22 degrees, the electromagnetic force ratio tends not to be 0%. The minimum value of the electrical angle θLP1 at which the electromagnetic force ratio is 0% is 21.2 degrees. Note that electromagnetic force ratios exceeding 10.0% are not plotted in FIG. 8 .

[0042] FIG. 9 illustrates the relationship between the electrical angle θLP2 in the first groove portion 51 and the electromagnetic force ratio. In FIG. 9, the electrical angle θLP2 is shown as the upper limit (e.g., in degrees) of the groove. The electromagnetic force ratio corresponds to the index shown in FIG. 5. However, the electromagnetic force ratio here is an index obtained when the electrical angle θLP2 in the first groove portion 51 is changed in a rotating electric machine 10 having chamfers 40 and grooves 50 (first groove portion 51 and second groove portion 52). As shown in FIG. 9, when the electrical angle θLP2 is less than approximately 41 degrees, the electromagnetic force ratio tends not to be 0%. Furthermore, the maximum value of the electrical angle θLP2 at which the electromagnetic force ratio becomes 0% is 42.3 degrees. Note that electromagnetic force ratios exceeding 10.0% are not plotted in FIG. 9.

[0043] Therefore, in this embodiment, the first range θLW is set to a range in which the electrical angle θLP1 is equal to or greater than 21.2 degrees and the electrical angle θLP2 is equal to or less than 42.3 degrees, and the first groove portion 51 is arranged within this first range θLW.

[0044] FIG. 10 illustrates the relationship between the first range θLW and the electromagnetic force ratio. The first range θLW is shown in FIG. 10 as the groove range (e.g., degrees). This groove range indicates the optimal range of the first range θLW, calculated as the difference between the electrical angles θLP2 and θLP1. The electromagnetic force ratio conforms to the index shown in FIG. 5 . However, the electromagnetic force ratio here is an index when the first range θLW is changed in a rotating electric machine 10 having chamfers 40 and grooves 50 (first groove portion 51 and second groove portion 52). As shown in FIG. 10 , when the first range θLW is greater than or equal to 19.4 degrees and less than or equal to 20.8 degrees, the electromagnetic force ratio can be 0%. When the first range θLW is outside this range, the electromagnetic force ratio exceeds 10.0%, and is therefore not plotted in FIG. 10 .

[0045] Therefore, in this embodiment, the first grooves 51 are arranged over the entire range of the first range θLW where the electrical angle θLP1 is equal to or greater than 19.4 degrees and the electrical angle θLP2 is equal to or less than 20.8 degrees.

[0046] FIG. 11 illustrates the relationship between the electrical angle θRP1 in the second groove portion 52 and the electromagnetic force ratio. The electrical angle θRP1 is shown as the lower limit (e.deg.) of the groove in FIG. 11 . The electromagnetic force ratio corresponds to the index shown in FIG. 5 . However, the electromagnetic force ratio here is an index when the electrical angle θRP1 in the second groove portion 52 is changed in a rotating electric machine 10 having chamfers 40 and grooves 50 (first groove portion 51 and second groove portion 52). As shown in FIG. 11 , when the electrical angle θRP1 exceeds approximately 19 degrees, the electromagnetic force ratio tends not to be 0%. The minimum value of the electrical angle θRP1 at which the electromagnetic force ratio becomes 0% is 18.4 degrees. Note that electromagnetic force ratios exceeding 10.0% are not plotted in FIG. 11 .

[0047] FIG. 12 illustrates the relationship between the electrical angle θRP2 in the second groove portion 52 and the electromagnetic force ratio. The electrical angle θRP2 is shown in FIG. 12 as the upper limit (e.g., degrees) of the groove. The electromagnetic force ratio corresponds to the index shown in FIG. 5 . However, the electromagnetic force ratio here is an index when the electrical angle θRP2 in the second groove portion 52 is changed in a rotating electric machine 10 having chamfers 40 and grooves 50 (first groove portion 51 and second groove portion 52). As shown in FIG. 12 , when the electrical angle θRP2 is less than approximately 34 degrees, the electromagnetic force ratio tends not to be 0%. Furthermore, the maximum value of the electrical angle θRP2 at which the electromagnetic force ratio becomes 0% is 34.4 degrees. Note that electromagnetic force ratios exceeding 10.0% are not plotted in FIG. 12 .

[0048] Therefore, in this embodiment, the second range θRW is set to a range in which the electrical angle θRP1 is equal to or greater than 18.4 degrees and the electrical angle θRP2 is equal to or less than 34.4 degrees, and the second groove portion 52 is arranged within this second range θRW.

[0049] FIG. 13 illustrates the relationship between the second range θRW and the electromagnetic force ratio. The second range θRW is shown in FIG. 13 as the groove range (e.g., degrees). This groove range indicates the optimal range of the second range θRW, calculated as the difference between the electrical angles θRP2 and θRP1. The electromagnetic force ratio conforms to the index shown in FIG. 5. However, the electromagnetic force ratio here is an index when the second range θRW is changed in a rotating electric machine 10 having chamfers 40 and grooves 50 (first groove portions 51 and second groove portions 52). As shown in FIG. 13, when the second range θRW is greater than or equal to 15.4 degrees and less than or equal to 16.0 degrees, the electromagnetic force ratio can be 0%. When the second range θRW exceeds 16.0 degrees, the electromagnetic force ratio exceeds 10.0%, and therefore is not plotted in FIG. 13.

[0050] Therefore, in this embodiment, the second groove portions 52 are arranged over the entire range of the second range θRW where the electrical angle θRP1 is equal to or greater than 15.4 degrees and the electrical angle θRP2 is equal to or less than 16.0 degrees.

[0051] The depths of the first groove portion 51 and the second groove portion 52 in the groove 50 will now be described. FIG. 14 is a diagram showing the relationship between the difference in depth between the two recesses 541 and 551 in the first groove portion 51 and the electromagnetic force ratio. This difference in depth is the ratio (%) of the difference (D541-D551) between the maximum distance D541 of the recess 541 and the maximum distance D551 of the recess 551 shown in FIG. 3 to the diameter of the circumscribed circle CO (the distance Dia shown in FIG. 1), and is shown as the difference in groove depth in FIG. 14. The electromagnetic force ratio is equivalent to the index shown in FIG. 5. However, the electromagnetic force ratio here is an index when the groove depth of the first groove portion 51 is changed in a rotating electric machine 10 having a chamfer 40 and a groove 50 (the first groove portion 51 and the second groove portion 52). As shown in FIG. 14, when the difference in groove depth, that is, the ratio of the difference between the maximum distances D541 and D551 to the diameter Dia of the circumscribing circle CO ((D541-D551 / Dia) x 100) is less than 0% or exceeds 0.17%, the electromagnetic force ratio tends not to be 0%. In these cases, the electromagnetic force ratio exceeds 10.0%, and therefore is not plotted in FIG. 14. Therefore, the groove depth of the first groove portion 51 may be 0% or more and 0.17% or less (0≦(D541-D551 / Dia) x 100≦0.17).

[0052] FIG. 15 is a diagram showing the relationship between the difference in depth between the two recesses 542 and 552 in the second groove portion 52 and the electromagnetic force ratio. This difference in depth is the ratio (%) of the difference (D542-D552) between the maximum distance D542 of the recess 542 shown in FIG. 3 and the maximum distance D552 of the recess 552 to the diameter of the circumscribed circle CO (the distance Dia shown in FIG. 1), and is shown in FIG. 15 as the difference in groove depth. The electromagnetic force ratio is equivalent to the index shown in FIG. 5. However, the electromagnetic force ratio here is an index when the groove depth of the second groove portion 52 is changed in a rotating electric machine 10 having a chamfer 40 and a groove 50 (first groove portion 51 and second groove portion 52). As shown in FIG. 15, when the difference in groove depth, that is, the ratio of the difference between the maximum distances D541 and D551 to the diameter Dia of the circumscribing circle CO ((D542-D552 / Dia) x 100) is less than -0.4% or more than 0.1%, the electromagnetic force ratio tends not to be 0%. When the difference in groove depth is less than -0.4%, the electromagnetic force ratio exceeds 10.0%, and therefore is not plotted in FIG. 15. Therefore, the groove depth of the second groove portion 52 may be -0.4% or more and 0.1% or less (-0.4 ≦ (D541-D551 / Dia) x 100 ≦ 0.1).

[0053] As described above, this embodiment can reduce the electromagnetic forces of harmonics related to integer multiples of the sixth electrical angle (the twenty-fourth mechanical angle) generated in the rotating electric machine 10, particularly six types of order components: the sixth, twelfth, and twenty-fourth electrical angles in the radial direction, and the sixth, twelfth, and twenty-fourth electrical angles in the circumferential direction. The effect of reducing the electromagnetic forces of harmonics according to this embodiment will be explained by comparing it with a comparative example. The rotating electric machine 10 according to this embodiment (hereinafter referred to as the present invention) has both the chamfer 40 and the groove 50 (first groove portion 51 and second groove portion 52) as shown in FIGS. 1 and 2 . As a comparative example to this embodiment, FIGS. 16A , 16B , 16C , and 16D each show a comparative example in which the grooves 501, 502, and 503 of the rotor core 24 have different configurations from the groove 50. Note that components in these comparative examples that are the same as or similar to those in the present invention are designated by the same reference numerals in the drawings.

[0054] In FIG. 16A , a groove 501 is formed in each magnetic pole of the rotor core 24 with only one recessed portion without a protruding portion 53. The groove 501 is curved in a concave arc shape as a whole, and the groove bottom 56 is also curved rather than flat. In FIG. 16B , a groove 502 is formed in each magnetic pole of the rotor core 24 with only one recessed portion without a protruding portion 53. Unlike groove 501, groove 502 has a flat groove bottom 57, and the portion other than groove bottom 57 is curved in a concave arc shape. In FIG. 16C , a groove 503 is formed in each magnetic pole of the rotor core 24 with two recessed portions 59, one on each circumferential side of a protruding portion 58. These protruding portions 58 and recessed portions 59 are rectangular. In FIG. 16D , the rotor core 24 does not have a portion corresponding to the groove 50. In other words, the outer peripheral surface 24a of the rotor core 24 is a continuous surface without any irregularities.

[0055] Additionally, comparative examples are assumed in which the arrangement of chamfers on the teeth 21 of the stator core 16 is different from that of the present invention. These comparative examples are assumed to be three examples: an example in which all teeth 21 are provided with chamfers of the same shape as chamfer 40; an example in which teeth 21 that define the edges of openings 20 a of slots 20 between which armature windings 18 of the same phase pass are provided with chamfers of the same shape as chamfer 40; and an example in which none of the teeth 21 have a portion corresponding to chamfer 40.

[0056] Here, we will consider the electromagnetic force ratio for 20 examples that combine the five groove configurations of the rotor core 24 shown in Figures 16A to 16D and the five groove configurations of the rotor core 24 shown in Figure 2 with the chamfered configuration of the stator core 16 described above and the four chamfered configurations of the stator core 16 shown in Figure 2. Figure 17 is a diagram showing the electromagnetic force ratio for each comparative example as a ratio when the present example is set to 0. 0% indicates that the electromagnetic force ratio is equal to or lower than the present example. Therefore, if the electromagnetic force ratio is higher than the present example, the electromagnetic force ratio of the comparative example will be a positive value, and if it is equal to or lower, the electromagnetic force ratio of the comparative example will be 0.

[0057] 17, A to E on the horizontal axis indicate the groove configuration of rotor core 24, with A indicating the groove configuration of groove 501 shown in FIG. 16A, B indicating the groove configuration of groove 502 shown in FIG. 16B, C indicating the groove configuration of groove 503 shown in FIG. 16C, D indicating the groove configuration of groove 50 shown in FIG. 2, and E indicating the groove configuration (no groove) shown in FIG. 16D. Numbers 1 to 4 on the horizontal axis indicate the chamfering configuration of stator core 16, with number 1 indicating a configuration in which chamfers 40 are provided on all teeth 21, number 2 indicating a configuration in which chamfers 40 are provided on teeth 21 between slots 20 of different phases, number 3 indicating a configuration in which chamfers are provided on teeth 21 between slots 20 of the same phase, and number 4 indicating a configuration in which no chamfers are provided. In FIG. 17, the combinations of groove configurations and chamfering configurations in this case and the comparative example are shown by combinations of A to E and 1 to 4. For example, Figure 16A shows the combination indicated by A1, Figure 16B shows the combination indicated by A2, Figure 16B shows the combination indicated by B2, Figure 16C shows the combination indicated by C2, Figure 16D shows the combination indicated by E2, and the combination indicated by D2 is the present case.

[0058] As shown in FIG. 17 , the electromagnetic force ratios of all the comparative examples other than the present invention, indicated by D2, exceed 0%. That is, the comparative examples other than the present invention, indicated by D2, have a higher total percentage exceedance of the electromagnetic force of six order components of radial electrical angle 6th, 12th, and 24th, and circumferential electrical angle 6th, 12th, and 24th, when the allowable range is set to 0, than the present invention. Therefore, by adopting the groove and chamfer configurations indicated by D2 in the present invention, it is possible to reduce harmonics related to integer multiples of the sixth electrical angle (24th mechanical angle) generated in the rotating electric machine 10, particularly the electromagnetic force of six order components of radial electrical angle 6th, 12th, and 24th, and circumferential electrical angle 6th, 12th, and 24th. That is, in the rotating electric machine 10, harmonics of the electromagnetic force at a targeted operating point can be suppressed, thereby reducing vibration and noise.

[0059] Although the embodiments of the present invention have been described above, the above-described embodiments are presented as examples and are not intended to limit the scope of the invention. Such novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as set forth in the claims.

[0060] 10... rotating electric machine, 12... stator, 14... rotor, 16... stator core, 16a... inner peripheral surface of stator core, 18, 18u, 18v, 18w... armature winding (coil), 18a... inner peripheral end of armature winding, 20, 20u, 20v, 20w... slot, 20a... opening, 21, 21a, 21b, 21c... teeth, 22... shaft (rotating shaft), 23, 23a, 23b, 23c... tip portion, 24... rotor core, 24a... outer peripheral surface of rotor core, 25... inner hole, 26... permanent magnet, 40... chamfer, 50, 501, 502, 503... groove, 51... first groove portion, 52... second groove portion, 53, 58, 531, 532... convex portion, 54, 59, 541, 542...recess, 55, 551, 552...recess, 56, 57...groove bottom, Ac...area of ​​chamfer, A14...direction of rotation of rotor, CL...central axis, CO...circumscribed circle, D541, D551, D542, D552...maximum distance from recess to circumscribed circle, Dia...diameter of circumscribed circle, L1...radial length of chamfer, L2...circumferential length of chamfer, P541, P551, P542, P552...continuous portion between recess and outer peripheral surface, S...area of ​​tip (tip area), W1...maximum circumferential width of tooth, W2...maximum circumferential width of tooth tip, θLP1, θLP2, θRP1, θRP2...electrical angle of groove, θLW...first range, θRW...second range.

Claims

1. A rotor comprising: a stator having a cylindrical stator core in which teeth and slots are arranged alternately in the circumferential direction, and armature windings of multiple phases wound around the teeth through the slots; a rotor core having a plurality of magnetic poles lined up along an outer circumferential surface facing the inner circumferential surface of the stator core with a gap therebetween, and a rotor having a plurality of permanent magnets provided on each of the magnetic poles, and rotatable around a central axis concentric with the stator core; wherein in the stator core, the tips of the teeth that define the edges of the openings of the slots on the inner circumferential surface between the slots through which the armature windings of different phases pass have a pair of chamfers formed by removing a portion of both circumferential ends of the inner circumferential surface; and in a cross section of the rotor core perpendicular to the central axis, an axis extending radially through the circumferential ends of the magnetic poles and the central axis is defined as the q-axis, and an axis electrically spaced 90 degrees circumferentially from the q-axis is defined as the d-axis. In each of the magnetic poles, the rotor core has a plurality of grooves in the outer surface that are recessed along the central axis, and each of the grooves forms a wave-like pattern with recesses on both sides of a protrusion lined up in the rotation direction of the rotor, and has a first groove portion arranged on the leading side of the rotation direction with respect to the d axis between the q axis that passes through both circumferential ends of the magnetic pole, and a second groove portion arranged on the trailing side of the rotation direction, and the first groove portion and the second groove portion are asymmetric with respect to the d axis.

2. A rotating electric motor as described in claim 1, wherein in the first groove portion, the maximum distance from one of the two recesses closer to the d-axis to a circumscribing circle tangent to the outer peripheral surface of the rotor core is greater than the maximum distance from the other recess to the circumscribing circle, and the convex portion is located inside the circumscribing circle; and in the second groove portion, the maximum distance from one of the two recesses closer to the d-axis to the circumscribing circle is greater than the maximum distance from the other recess to the circumscribing circle, and the convex portion is located inside the circumscribing circle.

3. A rotating electric machine as described in claim 1, wherein the first groove portions are arranged in a first range of electrical angles with respect to the d-axis of 21.2 degrees or more and 42.3 degrees or less, and the second groove portions are arranged in a second range of electrical angles with respect to the d-axis of 18.4 degrees or more and 34.4 degrees or less.

4. A rotating electric machine as described in claim 3, wherein the first groove portions are arranged over the entire range of the first range in which the electrical angle with respect to the d axis is 19.4 degrees or more and 20.8 degrees or less, and the second groove portions are arranged over the entire range of the second range in which the electrical angle with respect to the d axis is 15.4 degrees or more and 16.0 degrees or less.

5. A rotating electric machine according to claim 3, wherein the ratio of the difference in the maximum distance from each of the two recesses of the first groove portion to the circumscribing circle tangent to the outer peripheral surface of the rotor core to the diameter of the circumscribing circle is 0% or more and 0.17% or less, and the ratio of the difference in the maximum distance from each of the two recesses of the second groove portion to the circumscribing circle to the diameter is -0.4% or more and 0.1% or less.

6. A rotating electric machine as claimed in any one of claims 1 to 5, wherein the ratio of the total circumferential length of the pair of chamfers to the maximum circumferential width of the tip of the tooth is 42% or more and 89% or less, the ratio of the total area of ​​the pair of chamfers as seen from the direction of the central axis to the area of ​​the tip of the tooth without the chamfer as seen from the direction of the central axis is 5% or more and 13% or less, and the maximum circumferential width of the tip of the tooth is greater than the maximum circumferential width of the tooth other than the tip.

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