ROTOR OF A SYNCHRONOUS MOTOR

Abstract

Rotor (10) of a synchronous motor comprising the following: a rotor core (11) formed from a silicon steel plate or a soft magnetic material, the rotor core comprising several magnet insertion holes (17) formed at intervals in a circumferential direction and several slots (12a, 12b, 12c) formed on an outer circumferential side of the magnet insertion holes (17); and several permanent magnets (13) each embedded in the magnet insertion holes (17), wherein the orientation of a magnetic pole is a radial direction of the rotor core (11), wherein the multiple slots (12a, 12b, 12c) include an adjustment slot (12c) and magnet path forming slots (12a, 12b) which are formed at intervals in a cutting direction that intersects the orientation of the magnetic poles of each permanent magnet (13), at least one magnetic path forming slot (12a, 12b) is a set slot (12b), Magnetic paths (14a, 14b) are formed between the magnetic path-forming slots (12a, 12b) and at sections on an outside of the magnetic path-forming slots (12a) in the cutting direction on an outermost side, the adjusting slot (12c) between the adjusted slot (12b) and the permanent magnet (13) is formed such that the difference between the magnitudes of the magnetic flux passing through the adjacent magnetic paths (14a, 14b) is small for widths in the cutting direction. at least one of the magnetic path-forming slots (12a, 12b) is a non-adjusted slot (12a) without an adjustment slot (12c) between the at least one non-adjusted slot (12a) and the permanent magnet (13), the set slot (12b) and the unset slot (12a) are arranged adjacent to each other in the cutting direction, the magnetic path (14b), which is arranged between the set slot (12b) and the non-set slot (12a) on one side of the permanent magnet (13) and adjacent to the setting slot (12c) in the cutting direction, is a flux-limited magnetic path (14b), and the width (W4) of the flux-restricted magnetic path (14b) in the cutting direction is narrower than the width (W2) of the magnetic path on an outer side of the outermost magnetic path-forming slot.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a rotor of a synchronous motor. BACKGROUND

[0002] US 2016 / 0 211 709 A1 describes an internal permanent magnet motor comprising a stator and a rotor. The rotor core has a plurality of magnet insertion holes formed therein, into which corresponding permanent magnets are inserted. At least one slot and at least one caulked portion are formed between an outer rotor circumferential surface of the rotor and a radially outer insertion hole contour surface of the magnet insertion hole. At least a portion of the caulked portion is positioned between a pair of lines extending the width of the slot. In one example, the caulked portion is arranged on a radially outer side of a slot.

[0003] CN 2 06 211 698 U describes a rotor having a plurality of slots inclined to the left or right with respect to a centerline of a magnet insertion hole. A through hole is arranged at the centerline of the magnet insertion hole and communicates with the magnet insertion hole.

[0004] WO 2014 / 199 466 A1 and US 2016 / 0 190 880 A1 describe a rotor with a permanent magnet inserted into a magnet-receiving opening and with a slot formed on a radially outer side of the magnet-receiving opening. In the rotor core, projections of the magnet-receiving opening are formed in front of respective slots.

[0005] US 2017 / 0 294 814 A1 describes a rotor in which first slots are formed in front of second slots on an outer side of a magnet insertion hole.

[0006] JP 2001- 37 186 A describes a rotor with slots.

[0007] Permanent magnet synchronous motors have various structures. A surface magnet synchronous motor (hereinafter referred to as a "surface permanent magnet synchronous motor (SPM)"), which has permanent magnets attached to the outer peripheral surface of a rotor, and an embedded magnet synchronous motor (hereinafter referred to as an internal permanent magnet synchronous motor (IPM) or simply a "synchronous motor"), which has permanent magnets embedded in a rotor core, are known.

[0008] Compared to the SPM, which has permanent magnets attached to the rotor surface, the IPM, with its structure in which permanent magnets are embedded within the rotor, has a lower risk of permanent magnet straying when the rotor rotates at high speed. Flat permanent magnets can be used in the IPM because it eliminates the need to form curved surfaces on the permanent magnet to attach the permanent magnets to the rotor surface, as is the case with the SPM, thus reducing costs.

[0009] Accordingly, it is possible to achieve high reliability and low cost as long as the IPM can be used, for example, as a servo motor for driving a feed shaft of a machine tool. However, since the IPM has a larger inductance than the SPM, there is generally a delay in current tracking, resulting in poor controllability. Thus, the IPM is not suitable as a servo motor requiring high-speed, high-accuracy positioning.

[0010] In this regard, the rotor disclosed, for example, in JP H08-182 267 A is known as the rotor structure for reducing the inductance of the IPM. The structure of the rotor will be described below with reference to Fig. 5 described. Fig. 5 is a diagram illustrating an example of a cross-section of a rotor in the prior art IPM. A rotor 50 includes a rotor core 51 formed by stacking silicon steel plates and a plurality of permanent magnets 53. The rotor core 51 includes a plurality of magnet insertion holes 57 formed at intervals in a circumferential direction and a plurality of slots 52 formed on an outer peripheral side of the magnet insertion holes 57. Each permanent magnet 53 is embedded in the corresponding magnet insertion hole 57, with a magnetic pole oriented in a radial direction of the rotor core 51. The rotor 50 is connected to a rotating shaft (not shown) at its center. The magnet insertion holes 57 and the slots 52 are holes (cavities) opened in an axial direction of the rotating shaft (a direction penetrating the paper).Magnetic paths 54 are formed between the slots 52 adjacent to each other and between the slots 52 and an outer peripheral end of the rotor core 51.

[0011] A stator (not shown) is arranged on the outside of the rotor 50 in the radial direction. The stator has a substantially cylindrical shape, and a plurality of pole teeth are arranged on a cylindrical inner peripheral surface along the circumferential direction. The spaces between the pole teeth are called slots. A coil is wound around the pole teeth, passing through the slots, thereby forming a magnetic pole.

[0012] Fig. 6 is an enlarged partial view of the rotor 50 of Fig. 5 and shows magnetic flux lines 55 generated by the permanent magnets 53 and a magnetic flux line 56 generated by applying a current to the stator winding. In Fig. 6 shows that the slots 52 are arranged to prevent the passage of magnetic flux lines 56 generated by applying current to the stator winding. The inductance of the IPM is reduced by arranging the slots 52 in this manner and reducing the magnetic flux lines 56 generated by applying current to the stator winding. Meanwhile, the permanent magnet 53 is magnetized in an outward orientation in the radial direction. The magnetic flux lines 55 generated by the permanent magnet 53 pass through the magnetic paths 54 and flow to the stator.

[0013] Here, attention is drawn to a quantity of a magnetic flux passing through a magnetic path 54a far from a center of the magnetic pole and a magnetic path 54b near the center of the magnetic pole. Fig. 6, the number of magnetic flux lines 55 indicates a relative magnitude of a magnetic flux. For convenience of description, the widths of the magnetic path 54a and the magnetic path 54b (widths in a direction intersecting the orientation of the magnetic pole of the permanent magnet 53, widths in a left / right direction intersecting the direction along the side of the permanent magnet 53 in Fig. 6) are set to be equal. Thus, the same number (three) of magnetic flux lines flows from the permanent magnet 53 to the magnetic path 54a and the magnetic path 54b. In the magnetic path 54b, three inflow magnetic flux lines flow as they are. In contrast, since one magnetic flux line escapes to a connecting portion between the magnetic poles in the magnetic path 54a, only two magnetic flux lines of the three inflow magnetic flux lines flow to the stator. SUMMARY

[0014] As mentioned above, in the rotor of the prior art IPM, the magnetic flux lines generated by the permanent magnet 53 pass through the magnetic path 54b near the center of the magnetic pole, rather than the magnetic path 54a far from the center of the magnetic pole, and flow to the stator. Here, since the number of traversed magnetic flux lines and a magnetic attraction force are approximately proportional to each other, a large magnetic attraction force is generated in the magnetic path traversed by the large number of magnetic flux lines, and only a small magnetic attraction force is generated in the magnetic path traversed by the small number of magnetic flux lines. As mentioned above, when the number of traversed magnetic flux lines differs depending on the magnetic path, a difference is generated between the magnetic attraction forces depending on a rotational position of the rotor 50.That is, the magnetic attraction force increases as the magnetic path, along which a large number of magnetic flux lines pass, approaches the stator pole teeth, whereas the magnetic attraction force decreases as the magnetic path, along which a small number of magnetic flux lines pass, approaches the stator pole teeth. As stated above, when the magnetic attraction force fluctuates depending on the rotational position of the rotor 50, torque ripples, called cogging torque, occur when the rotor 50 rotates.

[0015] For example, when a servo motor with a large cogging torque is used for the feed shaft of a machine tool, a problem arises that streaks appear on a cutting surface. An object of the present disclosure is to provide a rotor of a synchronous motor that can reduce cogging torque. The invention is defined in claim 1 and the subordinate claim.

[0016] The rotor of the synchronous motor of the present disclosure employs the following means to achieve the above-mentioned object.

[0017] A rotor of a synchronous motor of the present disclosure includes a rotor core formed using a silicon steel plate or a soft magnetic material, the rotor core including a plurality of magnet insertion holes formed at intervals in a circumferential direction and a plurality of slots formed on an outer peripheral side of the magnet insertion holes, and a plurality of permanent magnets each embedded in the magnet insertion holes and whose orientation of a magnetic pole is a radial direction of the rotor core.The plurality of slots includes an adjustment slot and magnetic path forming slots formed at intervals in a cutting direction intersecting the orientation of the magnetic poles of each permanent magnet, wherein at least one magnetic path forming slot is an adjusted slot, magnetic paths are formed between the magnetic path forming slots and at portions on an outer side of the magnetic path forming slots on an outermost side in the cutting direction, and the adjustment slot is formed between the adjusted slot and the permanent magnet such that a difference between magnitudes of magnetic flux passing through the magnetic paths adjacent to each other is small for widths in the cutting direction.

[0018] In the rotor of a synchronous motor of the present disclosure, a maximum width of the adjustment slot in the cutting direction may be larger than a maximum width of the adjusted slot in the cutting direction.

[0019] In the rotor of a synchronous motor of the present disclosure, the adjustment slot may be connected to the magnet insertion hole.

[0020] In the rotor of a synchronous motor of the present disclosure, the set slot may be the magnetic path forming slot that is located near a center of the magnetic pole of the permanent magnet.

[0021] In a rotor of a synchronous motor of the present disclosure, the cutting direction may be a first direction along one side of the permanent magnet, and W1 is a shortest distance between an outer peripheral end of the rotor core and an edge of the magnet insertion hole on one end side of the permanent magnet in the first direction, W2 is a distance in the first direction and is a distance from one end of the permanent magnet to an edge of the magnetic path forming slot closest to the one end side, W3 is a distance in the first direction and is a distance from an edge of the set slot on the one end side to an edge of the magnetic path forming slot adjacent to the set slot on the one end side closest to the set slot, and W4,which is a distance in the first direction and a distance from an edge of the adjustment slot on the one-end side to an edge of the magnetic path forming slot adjacent to the adjustment slot on the one-end side close to the adjustment slot can satisfy a relationship of equation (1). (W2−W1) / W2=W4 / W3

[0022] In the rotor of a synchronous motor of the present disclosure, the magnetic path forming slots provided on both sides of the magnetic path forming slot provided to be near the center of the magnetic pole of the permanent magnet can be used as the adjusted slot.

[0023] A rotor of a synchronous motor of the present disclosure includes a rotor core formed of a silicon steel plate or a soft magnetic material, the rotor core including a plurality of magnet insertion holes formed at intervals in a circumferential direction and a plurality of slots formed on an outer peripheral side of the magnet insertion holes, and a plurality of permanent magnets each embedded in the magnet insertion holes and whose orientation of a magnetic pole is a radial direction of the rotor core.The plurality of slots are formed at intervals in a cutting direction intersecting the orientation of the magnetic poles of each permanent magnet, magnetic paths are formed between the slots and at portions on an outer side of the slots on an outermost side in the cutting direction, and two or more kinds of slots whose maximum widths are different in the cutting direction are formed such that a difference between magnitudes of magnetic flux passing across the magnetic paths adjacent to each other is small for widths in the cutting direction.

[0024] In the rotor of a synchronous motor of the present disclosure, at least one of the slots may be a deformation slot extending from a side of the permanent magnet to an outer peripheral side of the rotor core, and may have a shape in which a width changes in the cutting direction.

[0025] In the rotor of a synchronous motor of the present disclosure, a width of an end portion of the deformation slot in the cutting direction on the permanent magnet side may be larger than a width of an end portion of the deformation slot on the outer peripheral side of the rotor core in the cutting direction.

[0026] In the rotor of a synchronous motor of the present disclosure, the deformation slot may be connected to the magnet insertion hole.

[0027] In the rotor of a synchronous motor of the present disclosure, the deformation slot may be the slot provided to be located near the center of the magnetic pole of the permanent magnet.

[0028] In the rotor of a synchronous motor of the present disclosure, the cutting direction may be a first direction along one side of the permanent magnet, an end portion of the deformation slot on the permanent magnet side may be an extension portion, a portion between the end portion of the deformation slot on the permanent magnet side and the end portion on the outer peripheral side of the rotor core may be an intermediate portion, and W1, which is a shortest distance between an outer peripheral end of the rotor core and an edge of the magnet insertion hole on one side of one end of the permanent magnet in the first direction, W2, which is a distance in the first direction and is a distance from one end of the permanent magnet to an edge of the magnetic path forming slot closest to the one end on the one end side, W5,which is a distance in the first direction and is a distance from an edge of the intermediate portion of the deformation slot on the one-end side to an edge of the slot adjacent to the deformation slot on the one-end side that is close to the deformation slot, and W6, which is a distance in the first direction and is a distance from an edge of the extension portion of the deformation slot on the one-end side to an edge of the slot adjacent to the deformation slot on the one-end side that is close to the deformation slot, can satisfy a relationship of equation (2). (W2−W1) / W2=W6 / W5

[0029] In the rotor of a synchronous motor of the present disclosure, the slots provided on both sides of the slot so as to be located near the center of the magnetic poles of the permanent magnet can be used as the deformation slot.

[0030] According to the rotor of the synchronous motor of the present disclosure, it is possible to reduce a cogging torque of the synchronous motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] One or more embodiments of the present disclosure are described with reference to the following figures, in which: Fig. 1 is an enlarged partial cross-sectional view of a rotor according to a first embodiment; Fig. 2 is an enlarged partial cross-sectional view of a rotor according to a second embodiment; Fig. 3 is an enlarged partial cross-sectional view of a rotor according to a modification example of the second embodiment; Fig. 4 is an enlarged partial cross-sectional view of a rotor according to another modification example of the second embodiment; Fig. 5 is a diagram illustrating an example of a cross section of a rotor in a prior art IPM; and Fig. 6 an enlarged partial view of the rotor of Fig. 5 and represents magnetic flux lines generated by a permanent magnet. DESCRIPTION OF EMBODIMENTS

[0032] Hereinafter, an embodiment of a rotor of a synchronous motor of the present disclosure will be described with reference to the drawings. <Erste Ausführungsform>

[0033] Fig. Fig. 1 is an enlarged partial cross-sectional view of a rotor 10 of a synchronous motor according to a first embodiment. The rotor 10 of the synchronous motor of the present embodiment has the same configuration as the rotor 50 of the synchronous motor shown in Fig. 5, except for the shapes of the slots. That is, the rotor 10 includes, with reference to Fig. 1 and Fig. 5 a rotor core (corresponding to reference numeral 51 of Fig. 5) formed by stacking silicon steel plates, and a plurality of permanent magnets 13 (corresponding to the reference numeral 53 of Fig. 5). The rotor core 11 contains a plurality of magnet insertion holes 17 (corresponding to the reference numeral 57 of Fig. 5) formed at intervals in a circumferential direction. Each permanent magnet 13 is inserted into a corresponding magnet insertion hole 17, and an orientation of a magnetic pole is a radial direction of the rotor core 11. The rotor 10 is connected at its center to a rotating shaft (not shown). The magnet insertion holes 17 and the slots 12 to be described below are holes (cavities) opened in an axial direction of the rotating shaft (a direction penetrating the paper).

[0034] In the first embodiment and Fig. 5 is both the number of magnet insertion holes 17 (corresponding to the reference numeral 57 of Fig. 5) and the number of permanent magnets 13 (which correspond to the reference numeral 53 of Fig. 5) four. However, the number of magnet insertion holes and the number of permanent magnets can be optionally determined depending on the number of magnetic poles.

[0035] In this specification, it should be noted that the circumferential direction of the rotor 10 or the rotor core 11 does not need to be a strict circumferential direction. For example, when the number of magnet insertion holes 57 (permanent magnets 53) adjacent to each other at 90 degrees is Fig. 5 is two, although the magnet insertion holes 57 (permanent magnets 53) are arranged so that they face each other up and down or left and right in Fig. 5, it is represented that the magnet insertion holes 57 (permanent magnets 53) are arranged (formed) at intervals in the circumferential direction. And, for example, when the number of magnet insertion holes 57 (permanent magnets 53) in the rotor 10 (50) is two, although each magnet insertion hole 57 (permanent magnet 53) is arranged at the upper part and the lower part in the rotor 10 (50) or the left part and the right part in the rotor 10 (50), it is represented that the magnet insertion holes 57 (permanent magnets 53) are arranged (formed) at intervals in the circumferential direction.

[0036] In the following, the rotor 10 of the synchronous motor according to the first embodiment will be described with reference to Fig. 1. In general, since a cross section of the rotor 10 perpendicular to a rotation axis is uniform in a rotation axis direction, the shapes of the magnetic path, the slot, the permanent magnet, and the magnet insertion hole are described in the cross section perpendicular to the rotation axis.

[0037] The rotor core 11 of the rotor 10 is formed by stacking plate elements made of soft magnetic materials such as silicon steel plates in the rotation axis direction. The rotor core 11 includes a plurality of slots 12 formed on an outer peripheral side of the magnet insertion holes 17. The plurality of slots 12 includes an adjustment slot 12c and magnetic path-forming slots 12a and 12b formed at intervals in a direction (a cross-sectional direction) that intersects the orientation (the radial direction) of the magnetic pole of the permanent magnet 13. Fig. 1, the cutting direction is one direction (the left / right direction of Fig. 1) along one side of the permanent magnet 13, and hereinafter, the direction along the side of the permanent magnet 13 is appropriately referred to as a "first direction." At least one of the magnetic path-forming slots 12a and 12b is a set slot. Fig. 1, the magnetic path-forming slot 12b, which is positioned near the center of the magnetic pole of the permanent magnet 13, is the set slot. Magnetic paths 14 are formed between the magnetic path-forming slots 12a and 12b and at portions on the outer side of the magnetic path-forming slots 12a that are located on the outermost side in the first direction.

[0038] A stator (not shown) is arranged on the outer side of the rotor 10 in the radial direction. The stator has a substantially cylindrical shape, and a plurality of pole teeth are arranged on a cylindrical inner peripheral surface along the circumferential direction. The spaces between the pole teeth are called slots. A winding is wound around the pole teeth, passing through the slots, thereby forming a magnetic pole.

[0039] As in Fig. As shown in FIG. 1, the adjusted slot 12b and the adjustment slot 12c form a slot group 16. The maximum width of the adjustment slot 12c in the first direction is larger than the maximum width of the adjusted slot 12b in the first direction. The rotor 10 of the synchronous motor according to the first embodiment has the feature that the adjustment slot 12c is formed between the adjusted slot 12b and the permanent magnet 13 such that a difference between the magnitudes of the magnetic flux passing through the adjacent magnetic paths 14a and 14b is small for the widths in the first direction.

[0040] For the sake of convenience of description, Fig. 1, the widths of the magnetic path 14a and the magnetic path 14b (the widths in the first direction) are set to be equal. In Fig. 1, the widths of the adjusted slot 12b and the adjustment slot 12c are determined by a relationship expressed by equation (1) such that the magnitude of the magnetic flux passing through the magnetic path 14a and flowing to the stator and the magnitude of the magnetic flux passing through the magnetic path 14b and flowing to the stator are equal. (W2−W1) / W2=W4 / W3

[0041] In Fig. 1, W1, W2, W3 and W4 are shown in equation (1). In equation (1), W1 is the shortest distance between an outer peripheral end of the rotor core 11 and an edge of the magnet insertion hole 17 on one side (the right side in Fig. 1) of one end of the permanent magnet 13 in the first direction. W2 is a distance in the first direction and is a distance from one end (the right end in Fig. 1) of the permanent magnet 13 to an edge of the magnetic path forming slot 12a closest to one end of the one-end side. W3 is a distance in the first direction and is a distance from an edge of the set slot 12b on the side (the right side in Fig. 1) of one end to an edge of the magnetic path forming slot 12a adjacent to the adjusted slot 12b on the side of the one end closest to the adjusted slot 12b. W4 is a distance in the first direction and is a distance from an edge of the adjusting slot 12c on the side (the right side in Fig. 1) of one end to an edge of the magnetic path forming slot 12a adjacent to the adjusting slot 12c on the side of the one end near the adjusting slot 12c.

[0042] A flow of magnetic flux lines generated by the permanent magnet 13 in the structure is described with reference to Fig. 1. In Fig. 1, the permanent magnet 13 is magnetized in an outward orientation in the radial direction, and magnetic flux lines 15 indicate paths of the magnetic flux lines generated by the permanent magnet 13. The number of magnetic flux lines 15 indicating the paths of the magnetic flux lines indicates a relative magnitude of the magnetic flux. As described above, since the widths of the magnetic path 14a and the magnetic path 14b are the same, substantially the same number of magnetic flux lines flow from the permanent magnet 13 to all the magnetic paths. However, the adjustment slot 12c, which has the large width in the first direction, is arranged, and thus the magnetic flux lines flowing to the magnetic path 14b are restricted. Three magnetic flux lines flow to the magnetic path 14a and two magnetic flux lines flow to the magnetic path 14b.

[0043] When the sizes of the magnetic flux passing from the permanent magnet 13 through the magnetic paths 14 and flowing to the stator are paid attention, since two inflowing magnetic flux lines flow to the stator as they are in the magnetic path 14b, and one magnetic flux line escapes to a connecting portion between the magnetic poles in the magnetic path 14a, two magnetic flux lines of the three inflowing magnetic flux lines flow to the stator.

[0044] As stated above, the magnitudes of the magnetic flux passing through the magnetic paths 14 and flowing to the stator are equal in the magnetic path 14a and the magnetic path 14b due to the effect of the adjusting slot 12c, unlike Fig. 6, which illustrates a flow of magnetic flux lines in the rotor of the prior art IPM. Accordingly, since the magnetic attraction forces generated in all magnetic paths are equal and the magnetic attraction forces do not fluctuate as the rotor 10 rotates, it is possible to reduce cogging torque.

[0045] Although in the first embodiment described above, three magnetic path forming slots 12a and 12b are designed for one pole, the number of magnetic path forming slots 12a and 12b designed for one pole is not limited to three. A plurality of magnetic path forming slots 12a and 12b may be formed separately along the orientation (the up / down direction of Fig. 1) of the magnetic pole. A plurality of adjustment slots 12c may be provided separately along the orientation (the up / down direction of Fig. 1) the magnetic poles are provided.

[0046] Although in the first embodiment described above, the widths of the magnetic path 14a and the magnetic path 14b are the same, the present disclosure is not limited thereto.

[0047] In the first embodiment described above, the widths of the magnetic path forming slots 12a and 12b and the adjustment slot 12c are determined by equation (1) such that the magnitude of the magnetic flux passing through the magnetic path 14a and flowing to the stator and the magnitude of the magnetic flux passing through the magnetic path 14b and flowing to the stator are equal. However, the present disclosure is not limited to this example. When the adjustment slot 12c having the large width in the first direction is provided regardless of the relationship of equation (1), it is possible to reduce a difference between the magnitude of the magnetic flux passing through the magnetic path 14a and flowing to the stator and the magnitude of the magnetic flux passing through the magnetic path 14b and flowing to the stator, and it is possible to reduce the cogging torque.

[0048] The adjustment slot 12c may be connected to the magnet insertion hole 17. Even in this case, it is possible to obtain the same effect as described above.

[0049] In the first embodiment described above, the slot group 16 (the adjusted slot 12b and the adjustment slot 12c) is provided so as to be located near the center of the magnetic pole of the permanent magnet 13. However, the position of the slot group 16 is not limited as long as it is possible to reduce a change in the magnetic flux of the magnetic paths 14a and 14b that are adjacent to each other. For example, the adjustment slot 12c can be arranged between each of the magnetic path forming slots 12a (adjustment slots) and the permanent magnet 13 by using two magnetic path forming slots 12a located on both sides of the magnetic path forming slot 12b, which are provided so as to be located near the center of the magnetic pole of the permanent magnet 13, as the adjusted slots.This configuration is a configuration of a case where each of two deformation slots 18 is divided into an upper slot and a lower slot, and the upper slot and the lower slot are used as the set slot and the setting slot in . Fig. 4 (which is a modification example of the second embodiment) described below. <Zweite Ausführungsform>

[0050] Next, a rotor 10 of a synchronous motor according to a second embodiment will be described. Fig. 2 is an enlarged partial cross-sectional view of the rotor 10 of the synchronous motor according to the second embodiment. In the second embodiment, a deformation slot 18 is formed by combining the adjusted slot 12b and the adjustment slot 12c according to the first embodiment. Since the other configurations are the same as those of the first embodiment, the common configuration is appropriately omitted.

[0051] As in Fig. As shown in Fig. 2, the plurality of slots 12 and 18 are formed at intervals in a direction (a cutting direction) that intersects the orientation (the radial direction) of the magnetic pole of the permanent magnet 13. Similar to the first embodiment, the cutting direction in the second embodiment is the direction (the left / right direction, the first direction) along the side of the permanent magnet 13. The magnetic paths 14 are formed between the slots 12 and 18 and at the portions on the outside of the slots 12 on the outermost side in the first direction. The rotor 10 of the synchronous motor according to the second embodiment has the feature that two or more types of slots 12 and 18 whose maximum widths in the first direction are different are formed such that a difference between the magnitudes of the magnetic flux passing across the magnetic paths 14 adjacent to each other is small for the widths in the first direction.

[0052] At least one of the slots 12 and 18 is the deformation slot 18, which extends from one side of the permanent magnet 13 to an outer peripheral side of the rotor core 11 and has a shape in which a width in the first direction changes in the center. Fig. 2, a width of an end portion of the deformation slot 18 in the first direction on the permanent magnet 13 side is larger than a width of an end portion of the deformation slot 18 in the first direction on the outer peripheral side of the rotor core.

[0053] In Fig. 2, the widths of the magnetic path 14a and the magnetic path 14b (the widths in the first direction) are set to be equal. In Fig. 2, the widths of the slots 12 and 18 are determined by the relationship expressed by equation (2) such that the magnitude of the magnetic flux passing through the magnetic path 14a and flowing to the stator and the magnitude of the magnetic flux passing through the magnetic path 14b and flowing to the stator are equal. (W2−W1) / W2=W6 / W5

[0054] In Fig. 2, W1, W2, W5, and W6 are shown in equation (2). Hereinafter, the end portion of the deformation slot 18 on the permanent magnet 13 side is referred to as an "extension portion," and a portion between the end portion of the deformation slot 18 on the permanent magnet 13 side and its end portion on the outer peripheral side of the rotor core 11 is referred to as an "intermediate portion." In equation (2), W1 is the shortest distance between an outer peripheral end of the rotor core 11 and an edge of the magnet insertion hole 17 on one side (the right side in Fig. 2) one end of the permanent magnet 13 in the first direction. W2 is a distance in the first direction and is a distance from one end (the right end in Fig. 2) of the permanent magnet 13 to an edge of the slot 12 closest to one end of the one-end side. W5 is a distance in the first direction and is a distance from an edge of the intermediate portion of the deformation slot 18 on the side (the right side of Fig. 1) of one end to an edge of the slot 12 adjacent to the deformation slot 18 on the side of the one end that is close to the deformation slot 18. W6 is a distance in the first direction and is a distance from an edge of the extension portion of the deformation slot 18 on the side (the right side of Fig. 1) of one end to an edge of the slot 12 adjacent to the deformation slot 18 on the side of the one end which is close to the deformation slot 18.

[0055] A flow of magnetic flux lines generated by the permanent magnet 13 in the structure is described with reference to Fig. 2. In Fig. 2, the permanent magnet 13 is magnetized in an outward orientation in the radial direction, and magnetic flux lines 15 indicate paths of the magnetic flux lines generated by the permanent magnet 13. The number of magnetic flux lines 15 indicating the paths of the magnetic flux lines indicates a relative magnitude of the magnetic flux. As described above, since the widths of the magnetic path 14a and the magnetic path 14b are the same, substantially the same number of magnetic flux lines flow from the permanent magnet 13 to all magnetic paths. However, the maximum width of the deformation slot 18 in the first direction (the left / right direction of Fig. 2), which is arranged to be near the center of the magnetic pole, is larger than the maximum width of another slot 12 in the first direction, and thus the magnetic flux lines flowing to the magnetic path 14b are limited. Three magnetic flux lines flow to the magnetic path 14a, and two magnetic flux lines flow to the magnetic path 14b. In this case, if the magnitude of the magnetic flux flowing from the permanent magnet 13 through the magnetic paths 14 and flowing to the stator is taken into account, since two inflowing magnetic flux lines flow to the stator when located in the magnetic path 14b, and one magnetic flux line escapes to a connecting portion between the magnetic poles in the magnetic path 14a, two magnetic flux lines of the three inflowing magnetic flux lines flow to the stator.

[0056] As stated above, the magnitudes of the magnetic flux passing through the magnetic paths 14 are equal due to the action of the deformation slot 18, unlike Fig. 6, which illustrates the flow of magnetic flux lines in the rotor of the prior art IPM. Accordingly, similar to the first embodiment, since the magnetic attraction forces generated in all magnetic paths 14 are equal and the magnetic attraction forces do not fluctuate as the rotor 10 rotates, it is possible to reduce the cogging torque.

[0057] Similar to the first embodiment, although in the second embodiment described above, three slots 12 and 18 are provided for one pole, the number of slots 12 and 18 provided for one pole is not limited to three. A plurality of slots 12 and 18 may be provided along the orientation (upward / downward direction in Fig. 2) of the magnetic pole individually.

[0058] Similar to the first embodiment, although in the second embodiment described above, the widths of the magnetic path 14a and the magnetic path 14b are the same, the present disclosure is not limited thereto.

[0059] In the second embodiment described above, the widths of the slots 12 and 18 are determined by equation (2) such that the magnitude of the magnetic flux passing through the magnetic path 14a and flowing to the stator and the magnitude of the magnetic flux passing through the magnetic path 14b and flowing to the stator are equal. However, the present disclosure is not limited to this example. When two or more types of slots 12 and 18 whose maximum widths are different are formed regardless of the relationship of equation (2), it is possible to reduce a difference between the magnitude of the magnetic flux passing through the magnetic path 14a and flowing to the stator and the magnitude of the magnetic flux passing through the magnetic path 14b and flowing to the stator, and it is possible to reduce the cogging torque.

[0060] The deformation slot 18 may be connected to the magnet insertion hole 17. Even in this case, it is possible to obtain the same effect as described above.

[0061] In the second embodiment described above, a portion where the width of the deformation slot 18 in the first direction is the largest (a portion where the width is maximized) is the end portion on the permanent magnet 13 side. However, the portion where the width is maximized may be another portion of the deformation slot 18. Fig. 3 is an enlarged partial cross-sectional view of a rotor according to a modification example of the second embodiment. As shown in Fig. 3, the section in which the width is maximized may be located near a substantially center of the deformation slot 18 in the direction (upward / downward direction of Fig. 2) lie along the orientation of the magnetic pole. Even in this case, it is possible to achieve the same effect as described above.

[0062] In the second embodiment described above, the deformation slot 18 is provided so as to be located near the center of the magnetic pole of the permanent magnet 13. However, the position of the deformation slot 18 is not limited as long as it is possible to reduce the difference between the magnitudes of the magnetic flux passing through the magnetic paths 14a and 14b adjacent to each other for the widths in the first direction. Fig. 4 is an enlarged partial cross-sectional view of a rotor according to another modification example of the second embodiment. As shown in Fig.4, two slots provided on both sides of the slot 12, which is located near the center of the magnetic pole of the permanent magnet 13, may be used as the deformation slots 18. Even in this case, it is possible to obtain the same effect as that described above.

Claims

[1] Rotor (10) of a synchronous motor comprising: a rotor core (11) formed of a silicon steel plate or a soft magnetic material, the rotor core including a plurality of magnet insertion holes (17) formed at intervals in a circumferential direction and a plurality of slots (12a, 12b, 12c) formed on an outer peripheral side of the magnet insertion holes (17); and a plurality of permanent magnets (13) each embedded in the magnet insertion holes (17), wherein the orientation of a magnetic pole is a radial direction of the rotor core (11), wherein the plurality of slots (12a, 12b, 12c) comprise an adjustment slot (12c) and magnetic path forming slots (12a, 12b) formed at intervals in a cutting direction intersecting the orientation of the magnetic poles of each permanent magnet (13), at least one magnetic path forming slot (12a, 12b) is a set slot (12b), Magnetic paths (14a, 14b) are formed between the magnetic path-forming slots (12a, 12b) and at portions on an outer side of the magnetic path-forming slots (12a) in the cutting direction on an outermost side, the adjustment slot (12c) is formed between the adjusted slot (12b) and the permanent magnet (13) such that a difference between magnitudes of the magnetic flux passing through the magnetic paths (14a, 14b) adjacent to each other is small for widths in the cutting direction, at least one of the magnetic path-forming slots (12a, 12b) is a non-adjusted slot (12a) without an adjustment slot (12c) between the at least one non-adjusted slot (12a) and the permanent magnet (13), the adjusted slot (12b) and the non-adjusted slot (12a) are arranged adjacent to each other in the cutting direction, the magnetic path (14b) arranged between the adjusted slot (12b) and the non-adjusted slot (12a) on one side of the permanent magnet (13) and adjacent to the adjustment slot (12c) in the cutting direction is a flux-restricted magnetic path (14b), and the width (W4) of the flux-restricted magnetic path (14b) in the cutting direction is narrower than the width (W2) of the magnetic path on an outer side of the outermost magnetic path-forming slot. [2] The rotor (10) of a synchronous motor according to claim 1, wherein a maximum width of the adjustment slot (12c) in the cutting direction is larger than a maximum width of the adjusted slot (12b) in the cutting direction. [3] A rotor (10) of a synchronous motor according to claim 1 or 2, wherein the adjusting slot (12c) is connected to the magnet insertion hole (17). [4] The rotor (10) of a synchronous motor according to any one of claims 1 to 3, wherein the set slot (12b) is the magnetic path forming slot which is provided to be near a center of the magnetic pole of the permanent magnet (13). [5] Rotor (10) of a synchronous motor according to claim 4, wherein the cutting direction is a first direction along one side of the permanent magnet (13) and W1, which is a shortest distance between an outer peripheral end of the rotor core (10) and an edge of the magnet insertion hole (17) on one end side of the permanent magnet (13) in the first direction, W2, which is a distance in the first direction and is a distance from one end of the permanent magnet (13) to an edge of the magnetic path forming slot (12a) closest to one end on the one end side, W3, which is a distance in the first direction and is a distance from an edge of the adjusted slot (12b) on the one end side to an edge of the magnetic path forming slot (12a) adjacent to the adjusted slot (12b) on the one end side closest to the adjusted slot (12b), and W4, which is a distance in the first direction and is a distance from an edge of the adjusted slot (12c) on the one end side to a Edge of the magnetic path forming slot (12a),which is adjacent to the adjustment slot (12c) on the side of one end which is close to the adjustment slot (12c), is to satisfy a relationship according to equation (1):, (W2−W1) / W2=W4 / W3 [6] The rotor (10) of a synchronous motor according to any one of claims 1 to 3, wherein the magnetic path forming slots (12a) provided on both sides of the magnetic path forming slot (12b) provided to be close to the center of the magnetic pole of the permanent magnet (13) are used as the set slot. [7] Rotor (10) of a synchronous motor, comprising: a rotor core (11) formed using a silicon steel plate or a soft magnetic material, the rotor core including a plurality of magnet insertion holes (17) formed at intervals in a circumferential direction and a plurality of slots (12, 18) formed on an outer peripheral side of the magnet insertion holes (17); and a plurality of permanent magnets (13) each embedded in the magnet insertion holes (17) and whose orientation of a magnetic pole is a radial direction of the rotor core (11), wherein the plurality of slots (12, 18) are formed at intervals in a cutting direction intersecting the orientation of the magnetic poles of each permanent magnet (13), Magnetic paths (14a, 14b) are formed between the slots (12, 18) and at portions on an outer side of the slots (12) on an outermost side in the cutting direction, two or more types of slots (12, 18) whose maximum widths are different in the cutting direction are formed such that a difference between magnitudes of the magnetic flux passing through the magnetic paths (14a, 14b) adjacent to each other is small for widths in the cutting direction, at least two of the slots (12, 18) are deformation slots (18), each of which extends from one side of the permanent magnet (13) to an outer peripheral side of the rotor core (11) and has a shape in which the width in the cutting direction at the end on the side of the permanent magnet (13) is wider than the width at the other end on the outer peripheral side of the rotor core (11), at least one of the slots (12, 18) is a non-deformation slot (12) extending from one side of the permanent magnet (13) to an outer peripheral side of the rotor core (11) and having a constant width in the cutting direction, the at least two deformation slots (18) are formed adjacent to and on respective sides of the non-deformation slot (12) which is located near the center of a magnetic pole of the permanent magnet (13), the magnetic path (14b) located between the deformation slot (18) and the non-deformation slot (12) and adjacent to an end of the deformation slot (18) having a maximum width in the cutting direction is a flux-limited magnetic path (14b), and the width (W6) in the cutting direction of the flux-restricted magnetic path (14b) is narrower than the width (W2) of the magnetic path on an outer side of the outermost slot. [8] A rotor (10) of a synchronous motor according to claim 7, wherein the deformation slot (18) is connected to the magnet insertion hole (17).

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