JP7484465B2 - Rotating Electric Machine - Google Patents

Description

The present invention relates to a rotating electric machine.

A rotating electric machine is known that includes a rotor core and permanent magnets arranged in holes in the rotor core. For example, Patent Document 1 describes a rotating electric machine in which three permanent magnets are arranged in a V shape.

International Publication No. 2018/159181

In rotating electric machines such as those described above, there is a demand for further reduction in torque ripple. In view of the above circumstances, one of the objects of the present invention is to provide a rotating electric machine having a structure that can reduce torque ripple.

One aspect of the rotating electric machine of the present invention includes a rotor rotatable about a central axis and a stator located radially outside the rotor. The rotor has a rotor core having a plurality of accommodation holes and a plurality of magnets respectively accommodated inside the plurality of accommodation holes. The stator has a stator core having an annular core back surrounding the rotor core and a plurality of teeth extending radially inward from the core back and arranged side by side at intervals in the circumferential direction, and a plurality of coils attached to the stator core. The plurality of magnets include a pair of first magnets arranged at intervals from each other in the circumferential direction and extending in a direction away from each other in the circumferential direction as viewed in the axial direction from the radially inner side to the radially outer side, and a second magnet arranged in a circumferential position between the pair of first magnets radially outside the radial inner ends of the pair of first magnets and extending in a direction perpendicular to the radial direction as viewed in the axial direction. The rotor core has a pair of first flux barrier parts arranged on either side of each of the first magnets in the direction in which the first magnets extend, a pair of second flux barrier parts arranged on either side of the second magnets in the direction in which the second magnets extend, and a third flux barrier part arranged at least one side between the first flux barrier part located on the radially outer side of the pair of first flux barrier parts arranged on either side of one of the pair of first magnets and one of the pair of second flux barrier parts, and between the first flux barrier part located on the radially outer side of the pair of first flux barrier parts arranged on either side of the other of the pair of first magnets and the other of the pair of second flux barrier parts. In a certain state in which the circumferential center of the second magnet is arranged at the same circumferential position as the circumferential center of one of the teeth, the third flux barrier part is located on the radially inner side of the other one of the teeth.

According to one aspect of the present invention, torque ripple can be reduced in a rotating electric machine.

FIG. 1 is a cross-sectional view showing a rotating electric machine according to the present embodiment. FIG. 2 is a cross-sectional view showing a part of the rotating electric machine of this embodiment, taken along line II-II in FIG. FIG. 3 is a cross-sectional view showing a magnetic pole portion of the rotor and a part of the stator core of the present embodiment. FIG. 4 is a diagram showing an example of the 48th-order component of the magnetic flux flowing between the rotor and the stator in this embodiment. FIG. 5 is a diagram showing an example of the 24th-order component of the magnetic flux flowing between the rotor and the stator in this embodiment. FIG. 6 is a graph showing the simulation results of the embodiment.

The Z-axis direction shown in each figure is an up-down direction with the positive side being the "upper side" and the negative side being the "lower side". The central axis J shown in each figure is an imaginary line that is parallel to the Z-axis direction and extends in the up-down direction. In the following description, the axial direction of the central axis J, i.e., the direction parallel to the up-down direction, is simply referred to as the "axial direction", the radial direction centered on the central axis J is simply referred to as the "radial direction", and the circumferential direction centered on the central axis J is simply referred to as the "circumferential direction". The arrow θ shown in each figure indicates the circumferential direction. The arrow θ points clockwise around the central axis J when viewed from above. In the following description, the side to which the arrow θ points in the circumferential direction based on a certain object, i.e., the side moving clockwise when viewed from above, is referred to as the "one circumferential side", and the side opposite to the side to which the arrow θ points in the circumferential direction based on a certain object, i.e., the side moving counterclockwise when viewed from above, is referred to as the "other circumferential side".

Note that the terms "upper", "upper side", and "lower side" are simply names used to describe the relative positions of the various parts, and the actual relative positions may be other than those indicated by these names.

As shown in FIG. 1, the rotating electric machine 1 of this embodiment is an inner rotor type rotating electric machine. In this embodiment, the rotating electric machine 1 is a three-phase AC type rotating electric machine. The rotating electric machine 1 is, for example, a three-phase motor that is driven by a three-phase AC power supply. The rotating electric machine 1 includes a housing 2, a rotor 10, a stator 60, a bearing holder 4, and bearings 5a and 5b.

The housing 2 contains the rotor 10, the stator 60, the bearing holder 4, and the bearings 5a and 5b. The bottom of the housing 2 holds the bearing 5b. The bearing holder 4 holds the bearing 5a. The bearings 5a and 5b are, for example, ball bearings.

The stator 60 is located radially outside the rotor 10. The stator 60 has a stator core 61, an insulator 64, and a plurality of coils 65. The stator core 61 has a core back 62 and a plurality of teeth 63. The core back 62 is located radially outside the rotor core 20 described below. As shown in FIG. 2, the core back 62 is annular and surrounds the rotor core 20. The core back 62 is, for example, annular and centered on the central axis J.

The teeth 63 extend radially inward from the core back 62. The teeth 63 are arranged in a line at intervals in the circumferential direction. The teeth 63 are arranged, for example, at equal intervals around the circumference. For example, 48 teeth 63 are provided. In other words, the number of slots in the rotating electric machine 1 is, for example, 48. As shown in FIG. 3, each of the teeth 63 has a base portion 63a and an umbrella portion 63b.

The base 63a extends radially inward from the core back 62. The circumferential dimension of the base 63a is, for example, the same throughout the entire radial direction. Note that the circumferential dimension of the base 63a may, for example, become smaller toward the radially inward direction.

The umbrella portion 63b is provided at the radially inner end of the base portion 63a. The umbrella portion 63b protrudes from the base portion 63a on both sides in the circumferential direction. The circumferential dimension of the umbrella portion 63b is larger than the circumferential dimension at the radially inner end of the base portion 63a. The radially inner surface of the umbrella portion 63b is a curved surface along the circumferential direction. When viewed in the axial direction, the radially inner surface of the umbrella portion 63b extends in an arc shape centered on the central axis J. The radially inner surface of the umbrella portion 63b faces the outer peripheral surface of the rotor core 20 described later with a gap in the radial direction. In the teeth 63 adjacent to each other in the circumferential direction, the umbrella portions 63b are arranged side by side with a gap in the circumferential direction.

The coils 65 are attached to the stator core 61. As shown in FIG. 1, the coils 65 are attached to the teeth 63, for example, via the insulators 64. In this embodiment, the coils 65 are distributed wound. That is, each coil 65 is wound across the teeth 63. In this embodiment, the coils 65 are full-pitch wound. That is, the circumferential pitch between the slots of the stator 60 into which the coils 65 are inserted is equal to the circumferential pitch of the magnetic poles generated when a three-phase AC power supply is supplied to the stator 60. The number of poles of the rotating electric machine 1 is, for example, 8. That is, the rotating electric machine 1 is, for example, an 8-pole, 48-slot rotating electric machine. Thus, in the rotating electric machine 1 of this embodiment, when the number of poles is N, the number of slots is N×6. Note that the coils 65 are not illustrated in FIGS. 3 to 5. The insulators 64 are not illustrated in FIGS. 2 to 5.

The rotor 10 can rotate around a central axis J. As shown in FIG. 2, the rotor 10 has a shaft 11, a rotor core 20, and a plurality of magnets 40. The shaft 11 is cylindrical and extends axially around the central axis J. As shown in FIG. 1, the shaft 11 is supported by bearings 5a and 5b so as to be rotatable around the central axis J.

The rotor core 20 is a magnetic body. The rotor core 20 is fixed to the outer peripheral surface of the shaft 11. The rotor core 20 has a through hole 21 that passes through the rotor core 20 in the axial direction. As shown in FIG. 2, the through hole 21 has a circular shape centered on the central axis J when viewed in the axial direction. The shaft 11 passes through the through hole 21. The shaft 11 is fixed in the through hole 21 by, for example, press fitting. Although not shown in the figure, the rotor core 20 is formed, for example, by stacking multiple electromagnetic steel plates in the axial direction.

The rotor core 20 has a plurality of accommodating holes 30. The plurality of accommodating holes 30, for example, penetrate the rotor core 20 in the axial direction. A plurality of magnets 40 are accommodated inside the plurality of accommodating holes 30, respectively. The method of fixing the magnets 40 inside the accommodating holes 30 is not particularly limited. The plurality of accommodating holes 30 include a pair of first accommodating holes 31a, 31b and a second accommodating hole 32.

The type of the multiple magnets 40 is not particularly limited. The magnets 40 may be, for example, neodymium magnets or ferrite magnets. The multiple magnets 40 include a pair of first magnets 41a, 41b and a second magnet 42.

In this embodiment, the pair of first accommodating holes 31a, 31b, the pair of first magnets 41a, 41b, the second accommodating holes 32, and the second magnets 42 are provided in multiples at intervals in the circumferential direction. For example, eight pairs of first accommodating holes 31a, 31b, the pair of first magnets 41a, 41b, the second accommodating holes 32, and the second magnets 42 are provided.

The rotor 10 has a plurality of magnetic pole parts 70 each including a pair of first housing holes 31a, 31b, a pair of first magnets 41a, 41b, a second housing hole 32, and a second magnet 42. For example, eight magnetic pole parts 70 are provided. The magnetic pole parts 70 are arranged, for example, at equal intervals around one circumference along the circumferential direction. The magnetic pole parts 70 each include a magnetic pole part 70N having a magnetic pole of N pole on the outer peripheral surface of the rotor core 20 and a magnetic pole part 70S having a magnetic pole of S pole on the outer peripheral surface of the rotor core 20. For example, four magnetic pole parts 70N and four magnetic pole parts 70S are provided. The four magnetic pole parts 70N and four magnetic pole parts 70S are arranged alternately along the circumferential direction. The configuration of each magnetic pole part 70 is the same except that the magnetic poles on the outer peripheral surface of the rotor core 20 are different and the circumferential positions are different.

3, in the magnetic pole portion 70, the pair of first accommodating holes 31a, 31b are arranged at a distance from each other in the circumferential direction. The first accommodating hole 31a is located, for example, on one circumferential side (+θ side) of the first accommodating hole 31b. The first accommodating holes 31a, 31b extend, for example, in an axial direction in a direction inclined obliquely with respect to the radial direction. The pair of first accommodating holes 31a, 31b extend in a direction that separates them from each other in the circumferential direction as they move from the radial inner side to the radial outer side as viewed in the axial direction. In other words, the circumferential distance between the first accommodating hole 31a and the first accommodating hole 31b increases as they move from the radial inner side to the radial outer side. The first accommodating hole 31a is located, for example, on one circumferential side as they move from the radial inner side to the radial outer side. The first accommodating hole 31b is located, for example, on the other circumferential side (-θ side) as they move from the radial inner side to the radial outer side. The radially outer ends of the first housing holes 31a, 31b are located at the radially outer periphery of the rotor core 20.

When viewed in the axial direction, the first accommodating hole 31a and the first accommodating hole 31b are arranged on either side of the magnetic pole center line IL1 shown in FIG. 3 in the circumferential direction. The magnetic pole center line IL1 is an imaginary line that passes through the circumferential center of the magnetic pole portion 70 and the central axis J and extends in the radial direction. When viewed in the axial direction, the first accommodating hole 31a and the first accommodating hole 31b are arranged, for example, line-symmetrically with respect to the magnetic pole center line IL1. Hereinafter, a description of the first accommodating hole 31b may be omitted for its configuration that is similar to that of the first accommodating hole 31a except for its line-symmetrical configuration with respect to the magnetic pole center line IL1.

The first accommodating hole 31a has a first straight portion 31c, an inner end 31d, and an outer end 31e. The first straight portion 31c extends linearly in the direction in which the first accommodating hole 31a extends when viewed in the axial direction. The first straight portion 31c is, for example, rectangular when viewed in the axial direction. The inner end 31d is connected to the radially inner end of the first straight portion 31c. The inner end 31d is the radially inner end of the first accommodating hole 31a. The outer end 31e is connected to the radially outer end of the first straight portion 31c. The outer end 31e is the radially outer end of the first accommodating hole 31a. The first accommodating hole 31b has a first straight portion 31f, an inner end 31g, and an outer end 31h.

The second accommodating hole 32 is located circumferentially between the radially outer ends of the pair of first accommodating holes 31a, 31b. That is, in this embodiment, the second accommodating hole 32 is located circumferentially between the outer end 31e and the outer end 31h. The second accommodating hole 32 extends in a substantially straight line in a direction perpendicular to the radial direction when viewed in the axial direction, for example. The second accommodating hole 32 extends in a direction perpendicular to the magnetic pole center line IL1 when viewed in the axial direction, for example. The pair of first accommodating holes 31a, 31b and the second accommodating hole 32 are arranged along a ∇ shape when viewed in the axial direction, for example.

In this specification, "an object extends in a direction perpendicular to a certain direction" includes not only the case where an object extends in a direction strictly perpendicular to a certain direction, but also the case where an object extends in a direction approximately perpendicular to a certain direction. "A direction approximately perpendicular to a certain direction" includes a direction that is tilted within a range of a few degrees [°] from the direction strictly perpendicular to a certain direction due to manufacturing tolerances, etc.

When viewed in the axial direction, the magnetic pole center line IL1, for example, passes through the circumferential center of the second accommodating hole 32. In other words, the circumferential position of the circumferential center of the second accommodating hole 32 coincides with the circumferential position of the circumferential center of the magnetic pole portion 70, for example. The shape of the second accommodating hole 32 when viewed in the axial direction is, for example, a shape that is line-symmetrical with respect to the magnetic pole center line IL1. The second accommodating hole 32 is located on the radial outer periphery of the rotor core 20.

The second accommodating hole 32 has a second straight portion 32a, one end 32b, and the other end 32c. The second straight portion 32a extends linearly in the direction in which the second accommodating hole 32 extends when viewed in the axial direction. The second straight portion 32a is, for example, rectangular when viewed in the axial direction. The one end 32b is connected to an end portion on one circumferential side (+θ side) of the second straight portion 32a. The one end 32b is an end portion on one circumferential side of the second accommodating hole 32. The one end 32b is disposed at a distance from the outer end portion 31e of the first accommodating hole 31a on the other circumferential side (-θ side). The other end 32c is connected to an end portion on the other circumferential side (-θ side) of the second straight portion 32a. The other end 32c is an end portion on the other circumferential side of the second accommodating hole 32. The other end 32c is spaced apart from the outer end 31h on one circumferential side of the first receiving hole 31b.

The pair of first magnets 41a, 41b are respectively accommodated inside the pair of first accommodation holes 31a, 31b. The first magnet 41a is accommodated inside the first accommodation hole 31a. The first magnet 41b is accommodated inside the first accommodation hole 31b. The pair of first magnets 41a, 41b are, for example, rectangular when viewed in the axial direction. Although not shown, the first magnets 41a, 41b are, for example, rectangular. Although not shown, the first magnets 41a, 41b are, for example, provided throughout the entire axial direction in the first accommodation holes 31a, 31b. The pair of first magnets 41a, 41b are arranged at intervals from each other in the circumferential direction. The first magnet 41a is, for example, located on one circumferential side (+θ side) of the first magnet 41b.

The first magnet 41a extends along the first housing hole 31a when viewed in the axial direction. The first magnet 41b extends along the first housing hole 31b when viewed in the axial direction. For example, the first magnets 41a, 41b extend in a substantially straight line in a direction inclined obliquely to the radial direction when viewed in the axial direction. The pair of first magnets 41a, 41b extend in a direction that separates them from each other in the circumferential direction as they move from the radially inner side to the radially outer side when viewed in the axial direction. In other words, the circumferential distance between the first magnet 41a and the first magnet 41b increases as they move from the radially inner side to the radially outer side.

The first magnet 41a is located, for example, on one circumferential side (+θ side) from the radial inside to the radial outside. The first magnet 41b is located, for example, on the other circumferential side (-θ side) from the radial inside to the radial outside. The first magnet 41a and the first magnet 41b are arranged, for example, on either side of the magnetic pole center line IL1 when viewed in the axial direction. The first magnet 41a and the first magnet 41b are arranged, for example, line-symmetrically with respect to the magnetic pole center line IL1 when viewed in the axial direction. Below, a description of the first magnet 41b may be omitted for configurations similar to those of the first magnet 41a except for line-symmetrically with respect to the magnetic pole center line IL1.

The first magnet 41a is fitted into the first housing hole 31a. More specifically, the first magnet 41a is fitted into the first straight portion 31c. Of the side surfaces of the first magnet 41a, both side surfaces in a direction perpendicular to the direction in which the first straight portion 31c extends are in contact with, for example, the inner side surfaces of the first straight portion 31c. In the direction in which the first straight portion 31c extends as viewed in the axial direction, the length of the first magnet 41a is, for example, the same as the length of the first straight portion 31c.

When viewed in the axial direction, both ends of the first magnet 41a in the extension direction are disposed away from both ends of the first accommodation hole 31a in the extension direction. When viewed in the axial direction, the inner end 31d and the outer end 31e are disposed adjacent to each other on both sides of the first magnet 41a in the extension direction of the first magnet 41a. Here, in this embodiment, the inner end 31d constitutes the first flux barrier section 51a. The outer end 31e constitutes the first flux barrier section 51b. That is, when viewed in the axial direction, the rotor core 20 has a pair of first flux barrier sections 51a, 51b disposed on either side of the first magnet 41a in the extension direction of the first magnet 41a. When viewed in the axial direction, the rotor core 20 has a pair of first flux barrier sections 51c, 51d disposed on either side of the first magnet 41b in the extension direction of the first magnet 41b.

Thus, the rotor core 20 has first flux barrier sections 51a, 51b, 51c, and 51d arranged in pairs on either side of each of the first magnets 41a and 41b in the direction in which each of the first magnets 41a and 41b extends when viewed in the axial direction. The first flux barrier sections 51a, 51b, 51c, and 51d, the second flux barrier sections 52a and 52b described below, and the third flux barrier sections 53a and 53b described below are sections that can suppress the flow of magnetic flux. In other words, magnetic flux does not easily pass through each flux barrier section. Each flux barrier section is not particularly limited as long as it can suppress the flow of magnetic flux, and may include a gap section or a non-magnetic section such as a resin section.

The second magnet 42 is accommodated inside the second accommodation hole 32. The second magnet 42 is disposed at a circumferential position between the pair of first magnets 41a, 41b, radially outward of the radial inner ends of the pair of first magnets 41a, 41b. The second magnet 42 extends along the second accommodation hole 32 when viewed in the axial direction. The second magnet 42 extends in a direction perpendicular to the radial direction when viewed in the axial direction. The pair of first magnets 41a, 41b and the second magnet 42 are arranged, for example, along a ∇ shape when viewed in the axial direction.

In this specification, "the second magnet is disposed at a circumferential position between a pair of first magnets" means that the circumferential position of the second magnet is included in the circumferential position between the pair of first magnets, and the radial position of the second magnet relative to the first magnet is not particularly limited.

The shape of the second magnet 42 when viewed in the axial direction is, for example, a shape that is line-symmetrical with respect to the magnetic pole center line IL1. The second magnet 42 is, for example, rectangular when viewed in the axial direction. Although not shown, the second magnet 42 is, for example, rectangular. Although not shown, the second magnet 42 is, for example, provided throughout the entire axial direction within the second accommodating hole 32. The radially inner portion of the second magnet 42 is, for example, located circumferentially between the radially outer ends of the pair of first magnets 41a, 41b. The radially outer portion of the second magnet 42 is, for example, located radially outer than the pair of first magnets 41a, 41b.

The second magnet 42 is fitted into the second housing hole 32. More specifically, the second magnet 42 is fitted into the second straight portion 32a. Of the side surfaces of the second magnet 42, both side surfaces in the radial direction perpendicular to the direction in which the second straight portion 32a extends are in contact with, for example, the inner side surfaces of the second straight portion 32a. In the direction in which the second straight portion 32a extends as viewed in the axial direction, the length of the second magnet 42 is, for example, the same as the length of the second straight portion 32a.

When viewed in the axial direction, both ends of the second magnet 42 in the extension direction are disposed away from both ends of the second accommodating hole 32 in the extension direction. When viewed in the axial direction, one end 32b and the other end 32c are disposed adjacent to each other on both sides of the second magnet 42 in the direction in which the second magnet 42 extends. Here, in this embodiment, the one end 32b constitutes the second flux barrier portion 52a. The other end 32c constitutes the second flux barrier portion 52b. In other words, the rotor core 20 has a pair of second flux barrier portions 52a, 52b disposed on either side of the second magnet 42 in the direction in which the second magnet 42 extends when viewed in the axial direction. The pair of second flux barrier sections 52a, 52b and the second magnet 42 are located circumferentially between the first flux barrier section 51b, which is located on the radially outer side of the pair of first flux barrier sections 51a, 51b that sandwich the first magnet 41a, and the first flux barrier section 51d, which is located on the radially outer side of the pair of first flux barrier sections 51c, 51d that sandwich the first magnet 41b.

The magnetic poles of the first magnet 41a are arranged along a direction perpendicular to the direction in which the first magnet 41a extends when viewed in the axial direction. The magnetic poles of the first magnet 41b are arranged along a direction perpendicular to the direction in which the first magnet 41b extends when viewed in the axial direction. The magnetic poles of the second magnet 42 are arranged along the radial direction.

The magnetic poles of the first magnet 41a located on the radial outside, the magnetic poles of the first magnet 41b located on the radial outside, and the magnetic poles of the second magnet 42 located on the radial outside are the same as each other. The magnetic poles of the first magnet 41a located on the radial inside, the magnetic poles of the first magnet 41b located on the radial inside, and the magnetic poles of the second magnet 42 located on the radial inside are the same as each other.

In the magnetic pole portion 70N, the magnetic pole of the first magnet 41a located on the radial outside, the magnetic pole of the first magnet 41b located on the radial outside, and the magnetic pole of the second magnet 42 located on the radial outside are, for example, N poles. In the magnetic pole portion 70N, the magnetic pole of the first magnet 41a located on the radial inside, the magnetic pole of the first magnet 41b located on the radial inside, and the magnetic pole of the second magnet 42 located on the radial inside are, for example, S poles.

Although not shown in the figure, in the magnetic pole portion 70S, the magnetic poles of each magnet 40 are arranged in an inverted manner with respect to the magnetic pole portion 70N. In other words, in the magnetic pole portion 70S, the magnetic poles located on the radially outer side of the magnetic poles of the first magnet 41a, the magnetic poles located on the radially outer side of the magnetic poles of the first magnet 41b, and the magnetic poles located on the radially outer side of the magnetic poles of the second magnet 42 are, for example, S poles. In the magnetic pole portion 70S, the magnetic poles located on the radially inner side of the magnetic poles of the first magnet 41a, the magnetic poles located on the radially inner side of the magnetic poles of the first magnet 41b, and the magnetic poles located on the radially inner side of the magnetic poles of the second magnet 42 are, for example, N poles.

The rotor core 20 has a pair of third flux barrier portions 53a, 53b. A pair of third flux barrier portions 53a, 53b is provided for each magnetic pole portion 70. In each magnetic pole portion 70, the third flux barrier portion 53a and the third flux barrier portion 53b are arranged, for example, in line symmetry with respect to the magnetic pole center line IL1 when viewed in the axial direction. Hereinafter, the description of the third flux barrier portion 53b may be omitted for the same configuration as the third flux barrier portion 53a except for the point that it is line symmetric with respect to the magnetic pole center line IL1. The third flux barrier portions 53a, 53b are, for example, gap portions created by holes that penetrate the rotor core 20 in the axial direction. The third flux barrier portions 53a, 53b are, for example, circular when viewed in the axial direction.

The third flux barrier section 53a is disposed circumferentially between the first flux barrier section 51b, which is located radially outward of the pair of first flux barrier sections 51a, 51b arranged on either side of one of the pair of first magnets 41a, 41b, and one of the pair of second flux barrier sections 52a, 52b, the second flux barrier section 52a. The third flux barrier section 53a is disposed, for example, in the center between the first flux barrier section 51b and the second flux barrier section 52a in the circumferential direction.

The third flux barrier section 53b is disposed circumferentially between the first flux barrier section 51d located radially outward of the pair of first flux barrier sections 51c, 51d arranged on either side of the other first magnet 41b of the pair of first magnets 41a, 41b, and the other second flux barrier section 52b of the pair of second flux barrier sections 52a, 52b. The third flux barrier section 53b is disposed, for example, in the center between the first flux barrier section 51d and the second flux barrier section 52b in the circumferential direction.

The third flux barrier portions 53a and 53b are located on an extension line of the direction in which the second magnet 42 extends, as viewed in the axial direction. The third flux barrier portions 53a and 53b are located between a virtual curve IL6 that passes through both circumferential ends of the radial inner edge of the second magnet 42 and a virtual curve IL7 that passes through both circumferential ends of the radial outer edge of the second magnet 42, as viewed in the axial direction. The virtual curve IL6 is a virtual line that passes through both circumferential ends of the radial inner edge of the second magnet 42, as viewed in the axial direction, and extends in an arc shape centered on the central axis J. The virtual curve IL7 is a virtual line that passes through both circumferential ends of the radial outer edge of the second magnet 42, as viewed in the axial direction, and extends in an arc shape centered on the central axis J.

The third flux barrier portions 53a, 53b are, for example, located radially inward from the radial outer edge of the second magnet 42. The third flux barrier portions 53a, 53b are, for example, located radially outward from the radial inner edge of the second magnet 42. The third flux barrier portions 53a, 53b are, for example, located radially outward from the pair of first magnets 41a, 41b.

In this embodiment, the circumferential dimension W of the third flux barrier parts 53a and 53b is smaller than the circumferential dimension of the first flux barrier parts 51a, 51b, 51c, and 51d and the circumferential dimension of the second flux barrier parts 52a and 52b. In this embodiment, the circumferential dimension W of the third flux barrier parts 53a and 53b is the diameter of the circular third flux barrier parts 53a and 53b. The circumferential dimension W of the third flux barrier parts 53a and 53b is, for example, smaller than half the circumferential dimension of the first flux barrier parts 51a, 51b, 51c, and 51d and half the circumferential dimension of the second flux barrier parts 52a and 52b. The circumferential dimension W of the third flux barrier parts 53a and 53b is, for example, 2.4 mm or less. The circumferential dimension W of the third flux barrier portions 53a and 53b is preferably, for example, 0.6 mm or more and 2.1 mm or less. This is because torque ripple can be suitably reduced.

In this embodiment, the ratio of the circumferential dimension W of the third flux barrier portions 53a, 53b to the radius r of the rotor core 20 is 0.041 or less. It is preferable that the ratio of the circumferential dimension W of the third flux barrier portions 53a, 53b to the radius r of the rotor core 20 is 0.010 or more and 0.035 or less. This is because torque ripple can be suitably reduced.

In this embodiment, the ratio of the third flux barrier portion 53a to the circumferential distance L1 between the first flux barrier portion 51b and the second flux barrier portion 52a is, for example, 0.27 or less. The distance L1 shown in FIG. 4 is the circumferential distance between the first flux barrier portion 51b and the second flux barrier portion 52a at the radial position at the center of the circular third flux barrier portion 53a. The ratio of the third flux barrier portion 53a to the circumferential distance L1 between the first flux barrier portion 51b and the second flux barrier portion 52a is preferably 0.10 or more and 0.36 or less. This is because torque ripple can be suitably reduced. The circumferential distance L1 between the first flux barrier portion 51b and the second flux barrier portion 52a is, for example, 3.0 mm or more and 7.0 mm or less.

The radial distance L2 between the outer peripheral surface of the rotor core 20 and the third flux barrier portion 53a, and the distance L3 between the outer peripheral surface of the rotor core 20 and the center of the third flux barrier portion 53a are, for example, greater than the circumferential dimension W of the third flux barrier portion 53a. The distance L2 shown in FIG. 4 is the radial distance between the outer peripheral surface of the rotor core 20 and the third flux barrier portion 53a at the circumferential position at the center of the circular third flux barrier portion 53a. The distances L2 and L3 are, for example, greater than the radial distance from the outer peripheral surface of the rotor core 20 to the second magnet 42. The distance L2 is, for example, 0.7 mm or more and 4.2 mm or less. The distance L3 is, for example, 1.0 mm or more and 5.2 mm or less. The distance L3 is preferably 2.6 mm or more and 3.4 mm or less. This is because it is easy to suitably reduce torque ripple.

In a certain state in which the circumferential center of the second magnet 42 is disposed at the same circumferential position as the circumferential center of a certain tooth 63, the third flux barrier portions 53a and 53b are located radially inside the other tooth 63. In other words, in the certain state, the third flux barrier portions 53a and 53b overlap with the other tooth 63 in circumferential position. In this specification, "a certain object is located radially inside the other object" means that the certain object is located radially inside the other object with respect to the central axis, and the circumferential position of at least a part of the certain object is the same as the circumferential position of at least a part of the other object. Figures 2 to 5 show an example of the certain state. In Figures 2 to 5, the teeth 63 whose circumferential center is disposed at the same circumferential position as the circumferential center of the second magnet 42 are called teeth 66A. In other words, in the certain state shown in Figures 2 to 5, the teeth 66A correspond to "a certain tooth". In a certain state shown in Figures 2 to 5, when viewed in the axial direction, the magnetic pole center line IL1 passes through the circumferential center of the tooth 66A.

In a certain state shown in Figures 2 to 5, the teeth 63 adjacent to one circumferential side (+θ side) of the teeth 66A are called teeth 66B. The teeth 63 adjacent to the other circumferential side (-θ side) of the teeth 66A are called teeth 66C. The teeth 63 adjacent to one circumferential side of the teeth 66B are called teeth 66D. The teeth 63 adjacent to the other circumferential side of the teeth 66C are called teeth 66E. The teeth 63 adjacent to one circumferential side of the teeth 66D are called teeth 66F. In the following description, the certain state shown in Figures 2 to 5 will simply be called "certain state."

As shown in FIG. 3, in a certain state, the third flux barrier portion 53a is located radially inward of the tooth 66D. The third flux barrier portion 53b is located radially inward of the tooth 66E. In other words, in a certain state, the teeth 66D, 66E correspond to "another tooth." Here, each of the teeth 66D, 66E is a tooth that is located two teeth away from the tooth 66A that corresponds to the "certain tooth" in the circumferential direction. In other words, in this embodiment, the teeth 66D, 66E that are the "other tooth" are the teeth 63 that are located two teeth away from the "certain tooth" in the circumferential direction.

In this embodiment, in a certain state, the third flux barrier portion 53a is located radially inside a portion of the tooth 66D that is closer to the circumferential center of the second magnet 42 (-θ side). The portion of the tooth 66D that is closer to the circumferential center of the second magnet 42 is a portion of the tooth 66D that is closer to the circumferential center of the second magnet 42 than the tooth center line IL2. The tooth center line IL2 is an imaginary line that passes through the circumferential center of the tooth 66D and the central axis J and extends in the radial direction. In a certain state, the third flux barrier portion 53a is located circumferentially between the tooth center line IL2 and the imaginary line IL3 when viewed in the axial direction. The imaginary line IL3 is an imaginary line that passes through the end of the umbrella portion 63b of the tooth 66D on the other circumferential side (-θ side) and the central axis J when viewed in the axial direction and extends in the radial direction.

In this embodiment, in a certain state, the third flux barrier portion 53b is located circumferentially between the tooth center line IL4 and the imaginary line IL5 when viewed in the axial direction. The tooth center line IL4 is an imaginary line that passes through the circumferential center of the tooth 66E and the central axis J and extends radially. The imaginary line IL5 is an imaginary line that passes through the end of one circumferential side (+θ side) of the umbrella portion 63b of the tooth 66E and the central axis J when viewed in the axial direction and extends radially.

In a certain state, at least a part of the teeth 66B and at least a part of the teeth 66C are located radially outside the second magnet 42. The teeth 66B are teeth 63 arranged adjacent to each other in the circumferential direction between the teeth 66A and the teeth 66D. The teeth 66C are teeth 63 arranged adjacent to each other in the circumferential direction between the teeth 66A and the teeth 66E. In other words, in a certain state, at least a part of the teeth 66B and 66C arranged adjacent to each other in the circumferential direction between the teeth 66A, which is "a certain tooth," and the teeth 66D and 66E, which are "another tooth," are located radially outside the second magnet 42. In a certain state, for example, the other circumferential side (-θ side) of the teeth 66B and the one circumferential side (+θ side) of the teeth 66C are located radially outside the second magnet 42.

In a certain state, of the pair of first flux barrier sections 51a, 51b arranged on either side of the first magnet 41a, the first flux barrier section 51b located on the radially outer side is located on the radially inner side of the portion of the tooth 66D that is farther from the circumferential center of the second magnet 42 (+θ side). The portion of the tooth 66D that is farther from the circumferential center of the second magnet 42 is the portion of the tooth 66D that is farther from the circumferential center of the second magnet 42 than the tooth center line IL2.

The rotor core 20 has recesses 22a and 22b recessed radially inward from the outer circumferential surface of the rotor core 20. In this embodiment, a pair of recesses 22a and 22b are provided for each magnetic pole portion 70. In each magnetic pole portion 70, the recesses 22a and 22b are arranged, for example, in line symmetry with respect to the magnetic pole center line IL1 when viewed in the axial direction. Hereinafter, the description of the recess 22b may be omitted for the same configuration as the recess 22a except that it is line symmetric with respect to the magnetic pole center line IL1. The recess 22a is, for example, located radially outward from the first flux barrier portion 51b. The recess 22b is, for example, located radially outward from the first flux barrier portion 51d. The inner edges of the recesses 22a and 22b when viewed in the axial direction are, for example, approximately arc-shaped with a concave radially inward recess.

In a certain state, the recess 22a is disposed on the side (+θ side) that is circumferentially farther from the circumferential center of the second magnet than the circumferential center of the tooth 66D. In other words, the recess 22a is located on one circumferential side (+θ side) of the tooth center line IL2. In a certain state, at least a portion of the recess 22a is located radially inward of the tooth 66D. In this embodiment, in a certain state, the end portion on the other circumferential side (-θ side) of the recess 22a is located radially inward of the end portion on one circumferential side (+θ side) of the umbrella portion 63b of the tooth 66D.

According to this embodiment, the provision of the third flux barrier sections 53a, 53b can reduce torque ripple. A detailed explanation will be given below. As shown in FIG. 4, the magnetic flux flowing between the rotor 10 and the stator 60 may include magnetic flux that is emitted from the teeth 63, passes through the rotor core 20, and returns to the same teeth 63. Magnetic flux B48 shown in FIG. 4 is, for example, the 48th order component of the magnetic flux flowing between the rotor 10 and the stator 60.

Of the magnetic flux B48 shown in FIG. 4, magnetic flux B48a is, for example, a magnetic flux that is emitted radially inward from the circumferential center of the tooth 66A, passes through the rotor core 20, and returns to the end of the umbrella portion 63b of the tooth 66A on one circumferential side (+θ side). Magnetic flux B48a passes through a portion of the rotor core 20 that is located radially outside the second magnet 42.

Of the magnetic flux B48 shown in FIG. 4, magnetic flux B48b is, for example, a magnetic flux that is emitted radially inward from the circumferential center of tooth 66D and returns to the end of umbrella portion 63b of tooth 66D on the other circumferential side (-θ side) through rotor core 20. Magnetic flux B48b passes through a portion of rotor core 20 whose circumferential position is between first flux barrier portion 51b and second flux barrier portion 52a.

If the third flux barrier portion 53a were not provided, the magnetic flux B48b emitted from the teeth 66D into the rotor core 20 would travel a relatively large distance radially inward through the circumferential portion between the first flux barrier portion 51b and the second flux barrier portion 52a before returning to the teeth 66D, as shown by the two-dot chain line in FIG. 4.

On the other hand, because the second magnet 42 is provided, the magnetic flux B48a emitted from the teeth 66A travels around a portion of the rotor core 20 located radially outside the second magnet 42 in a relatively small area and returns to the teeth 66A. Therefore, if the third flux barrier portion 53a is not provided, the flow of the magnetic flux B48a flowing between the teeth 66A and the rotor core 20 and the flow of the magnetic flux B48b flowing between the teeth 66D and the rotor core 20 tend to differ greatly. This causes a difference in the fluctuation range of the magnetic force acting between the teeth 66A and the rotor core 20 and the fluctuation range of the magnetic force acting between the teeth 66D and the rotor core 20, which tends to cause variations in the magnetic force acting between each tooth 63 and the rotor core 20. Therefore, there is a problem that the torque ripple tends to become large.

In contrast, according to the present embodiment, the third flux barrier portion 53a is provided between the first flux barrier portion 51b and the second flux barrier portion 52a in the circumferential direction. In addition, in a certain state in which the circumferential center of the second magnet 42 is disposed at the same circumferential position as the circumferential center of a certain tooth 66A, the third flux barrier portion 53a is located radially inside the other tooth 66D. Therefore, as shown by the solid line in FIG. 4, the third flux barrier portion 53a can suppress the magnetic flux B48b emitted from the tooth 66D to the rotor core 20 from rotating significantly radially inward within the rotor core 20. This makes it easier for the magnetic flux B48b emitted from the tooth 66D to return to the tooth 66D through a portion of the rotor core 20 located radially outside the third flux barrier portion 53a. Therefore, it is easy to make the flow of magnetic flux B48b flowing between teeth 66D and rotor core 20 the same as the flow of magnetic flux B48a flowing between teeth 66A and rotor core 20. This makes it possible to prevent the fluctuation range of the magnetic force acting between teeth 66A and rotor core 20 from differing from the fluctuation range of the magnetic force acting between teeth 66D and rotor core 20, and to prevent variations in the magnetic force acting between each tooth 63 and rotor core 20. This makes it possible to reduce torque ripple.

In addition, according to this embodiment, the third flux barrier portion 53b is provided between the first flux barrier portion 51d and the second flux barrier portion 52b in the circumferential direction. In addition, in a certain state in which the circumferential center of the second magnet 42 is disposed at the same circumferential position as the circumferential center of a certain tooth 66A, the third flux barrier portion 53b is located radially inside the other tooth 66E. Therefore, similar to the magnetic flux B48b flowing between the teeth 66D and the rotor core 20 described above, the flow of the magnetic flux flowing between the teeth 66E and the rotor core 20 is easily made similar to the magnetic flux B48a flowing between the teeth 66A and the rotor core 20. This can further suppress the occurrence of variations in the magnetic force acting between each tooth 63 and the rotor core 20. Therefore, the variation in the flow of the magnetic flux in the circumferential direction can be further reduced, and the torque ripple can be further reduced.

For example, when the magnetic flux flowing between the rotor 10 and the stator 60 includes the magnetic flux B48 of the 48th order component as shown in FIG. 4, the magnetic flux flowing between the rotor 10 and the stator 60 also includes the magnetic flux B24 of the 24th order component as shown in FIG. 5. The magnetic flux B24 flows, for example, through the rotor core 20 between the tooth 66A located radially outside the circumferential center of the magnetic pole portion 70 and the teeth 66B, 66C adjacent to the tooth 66A in the circumferential direction. In FIG. 5, the magnetic flux B24 flows, for example, from the tooth 66A through the rotor core 20 to the tooth 66B. Such a magnetic flux B24 of the 24th order component is unlikely to flow to the teeth 66D, 66E arranged two teeth away from the tooth 66A in the circumferential direction.

Here, according to this embodiment, in a certain state, the teeth 66D, 66E located radially outside the third flux barrier portions 53a, 53b are the teeth 63 located two teeth away from the teeth 66A in the circumferential direction. Therefore, in a certain state, the 24th component magnetic flux B24 is unlikely to flow through the teeth 66D, 66E and the portion of the rotor core 20 located radially inside the teeth 66D, 66E. As a result, even if the third flux barrier portions 53a, 53b are provided, the flow of the 24th component magnetic flux B24 is unlikely to be impeded. Therefore, even if the third flux barrier portions 53a, 53b are provided, the torque ripple caused by the 24th component magnetic flux B24 can be suppressed from increasing. Thus, according to this embodiment, as described above, the torque ripple caused by the 48th component magnetic flux B48 can be reduced by the third flux barrier portions 53a, 53b, while the torque ripple caused by the 24th component magnetic flux B24 can be suppressed from increasing. This allows for more efficient torque ripple reduction.

In addition, according to this embodiment, in a certain state, at least a portion of the teeth 66B, 66C arranged adjacent to each other between a certain tooth 66A and another tooth 66D, 66E in the circumferential direction is located radially outside the second magnet 42. In a certain state, at least a portion of the teeth 66B, 66C is located radially outside the second magnet 42, so that the magnetic flux of the second magnet 42 can favorably facilitate the flow of the 24th component magnetic flux B24 from the tooth 66A to the teeth 66B, 66C. Therefore, the 24th component magnetic flux B24 is less likely to flow to the teeth 66D, 66E arranged two teeth away from the tooth 66A. As a result, in a certain state, the 24th component magnetic flux B24 is less likely to flow to the portion of the rotor core 20 located radially inside the teeth 66D, 66E. Therefore, even if the third flux barrier sections 53a and 53b are provided, the flow of the 24th-order component magnetic flux B24 is less likely to be impeded. Therefore, even if the third flux barrier sections 53a and 53b are provided, the increase in torque ripple caused by the 24th-order component magnetic flux B24 can be more effectively suppressed.

In addition, according to this embodiment, in a certain state, the first flux barrier portion 51b, which is located on the radially outer side of the pair of first flux barrier portions 51a, 51b arranged on either side of the first magnet 41a, is located on the radially inner side of the portion of the other tooth 66D that is far from the circumferential center of the second magnet 42 (+θ side). Therefore, the 48th component of the magnetic flux B48 emitted from the tooth 66D is blocked by the first flux barrier portion 51b and is unlikely to return to the portion of the tooth 66D that is far from the circumferential center of the second magnet 42. As a result, the 48th component of the magnetic flux B48 emitted from the tooth 66D is likely to return to the portion of the tooth 66D that is closer to the circumferential center of the second magnet 42 (-θ side), as shown in FIG. 4 by the magnetic flux B48b.

Here, in this embodiment, in a certain state, the third flux barrier portion 53a is located radially inward of the portion of the tooth 66D that is closer to the circumferential center of the second magnet 42 (-θ side). Therefore, the third flux barrier portion 53a can effectively prevent the magnetic flux B48b that is emitted from the tooth 66D and returns to the portion of the tooth 66D that is closer to the circumferential center of the second magnet 42 (-θ side) from circulating radially inward inside the rotor core 20. This allows the magnetic flux B48b that flows between the tooth 66D and the rotor core 20 to be effectively rectified by the third flux barrier portion 53a. Therefore, the torque ripple can be more effectively reduced.

Furthermore, for example, the 48th-order component magnetic flux B48 flowing between the rotor core 20 and the stator 60 also includes, for example, the magnetic flux B48c shown in FIG. 4. The magnetic flux B48c is magnetic flux that flows from the tooth 66D through the rotor core 20 to the tooth 66F adjacent to the tooth 66D. For example, the magnetic flux B48c is discharged from the tooth 66D into the rotor core 20, and then flows to the end of the umbrella portion 63b of the tooth 66F on the other circumferential side (-θ side). If a lot of such magnetic flux B48c flows, the circumferential balance of the 48th-order component magnetic flux B48 is lost, and torque ripple is likely to increase.

In contrast, according to this embodiment, the rotor core 20 has a recess 22a. In a certain state, the recess 22a is disposed on the side (+θ side) that is circumferentially farther from the circumferential center of the second magnet 42 than the circumferential center of the other tooth 66D. Therefore, the recess 22a makes it easier to narrow the path through which the magnetic flux B48c flows. This makes it possible to prevent the magnetic flux B48c from flowing too much, and to prevent the circumferential balance of the 48th component of the magnetic flux B48 from being lost. Therefore, the torque ripple can be further reduced.

Furthermore, according to this embodiment, in a certain state, at least a portion of the recess 22a is located radially inside one of the other teeth 66D. Therefore, the recess 22a makes it easy to preferably narrow the path through which the magnetic flux B48c emitted from the tooth 66D flows. This makes it possible to further prevent the magnetic flux B48c from flowing in large amounts. Therefore, the torque ripple can be further reduced.

In addition, according to this embodiment, the recess 22a is located radially outward of the first flux barrier portion 51b, which is located radially outward of the pair of first flux barrier portions 51a, 51b. This makes it possible to preferably narrow the radial distance between the recess 22a and the first flux barrier portion 51b. This makes it easier to more preferably narrow the path through which the magnetic flux B48c emitted from the tooth 66D flows. This makes it possible to further suppress the flow of a large amount of magnetic flux B48c. This makes it possible to further reduce torque ripple.

The effect obtained by providing the recess 22a described above can also be obtained by providing the recess 22b. In this embodiment, the provision of a pair of recesses 22a and 22b allows torque ripple to be reduced more effectively.

In addition, according to this embodiment, the circumferential dimension W of the third flux barrier portions 53a, 53b is 0.6 mm or more and 2.1 mm or less. By setting the circumferential dimension W of the third flux barrier portions 53a, 53b to a value within this range, the third flux barrier portions 53a, 53b can preferably rectify the 48th component of magnetic flux B48b. Therefore, it is easier to more preferably make the flow of magnetic flux B48b flowing between the teeth 66D, 66E and the rotor core 20 similar to the flow of magnetic flux B48a flowing between the teeth 66A and the rotor core 20. This more preferably reduces the variation in the magnetic flux flow in the circumferential direction, and more preferably reduces the torque ripple.

According to this embodiment, the rotating electric machine 1 is a three-phase AC rotating electric machine, and when the number of poles is N, the number of slots is N×6. In such a rotating electric machine 1, the magnetic flux flowing between the rotor 10 and the stator 60 includes an N×3-order magnetic flux component such as the above-mentioned 24th order magnetic flux B24, and an N×6-order magnetic flux component such as the above-mentioned 48th order magnetic flux B48. For example, when N=10, that is, when the rotating electric machine 1 is a rotating electric machine with 10 poles and 60 slots, the magnetic flux flowing between the rotor 10 and the stator 60 includes a 10×3-order, i.e., 30th order magnetic flux component, and a 10×6-order, i.e., 60th order magnetic flux component. In such a case, by providing the third flux barrier parts 53a and 53b, the torque ripple caused by the N×6-order magnetic flux component can be reduced as in the case of the above-mentioned 48th order magnetic flux B48, and the torque ripple caused by the N×3-order magnetic flux component can be suppressed from increasing as in the case of the above-mentioned 24th order magnetic flux B24. Therefore, by providing the third flux barrier sections 53a and 53b, it is easy to preferably achieve the effect of reducing the torque ripple described above in a rotating electric machine 1 with N poles and N x 6 slots.

In addition, according to this embodiment, the coil 65 is distributed and fully pitched. In the rotating electric machine 1 wound with the coil 65 in this manner, the magnetic flux flowing between the rotor 10 and the stator 60 includes an N×3 order magnetic flux component such as the 24th order magnetic flux B24 described above, and an N×6 order magnetic flux component such as the 48th order magnetic flux B48 described above. In such a case, the provision of the third flux barrier sections 53a and 53b can reduce the torque ripple caused by the N×6 order magnetic flux component, and can suppress the increase in the torque ripple caused by the N×3 order magnetic flux component. Therefore, by providing the third flux barrier sections 53a and 53b, it is easy to preferably obtain the effect of reducing the torque ripple described above in a rotating electric machine 1 having N poles and N×6 slots.

The present invention is not limited to the above-mentioned embodiment, and other configurations may be adopted within the scope of the technical concept of the present invention. In the above-mentioned embodiment, the third flux barrier section is provided both between the first flux barrier section located radially outward among the pair of first flux barrier sections arranged to sandwich one of the pair of first magnets and one of the pair of second flux barrier sections, and between the first flux barrier section located radially outward among the pair of first flux barrier sections arranged to sandwich the other of the pair of first magnets and the other of the pair of second flux barrier sections, but this is not limited to the above. The third flux barrier section may be provided at least in one of the following positions: between the first flux barrier section located radially outward among the pair of first flux barrier sections arranged to sandwich one of the pair of first magnets and one of the pair of second flux barrier sections, and between the first flux barrier section located radially outward among the pair of first flux barrier sections arranged to sandwich the other of the pair of first magnets and the other of the pair of second flux barrier sections. That is, in the above-described embodiment, each magnetic pole portion 70 may be configured to include only one of the pair of third flux barrier portions 53a, 53b.

The shape of the third flux barrier portion is not particularly limited. The third flux barrier portion may be, for example, elliptical or polygonal when viewed in the axial direction. When the third flux barrier portion is formed by a hole, the hole may be a hole having a bottom. The third flux barrier portion may be formed by disposing a non-magnetic material such as a resin in a hole provided in the rotor core. When multiple third flux barrier portions are provided, the multiple third flux barrier portions may include third flux barrier portions having different shapes from each other. As long as the third flux barrier portion is located between the first flux barrier portion and the second flux barrier portion in the circumferential direction, the radial position of the third flux barrier portion is not particularly limited.

A plurality of third flux barrier sections may be provided between one first flux barrier section and one second flux barrier section. For example, in the above-described embodiment, a plurality of third flux barrier sections 53a may be provided between the first flux barrier section 51b and the second flux barrier section 52a in the circumferential direction. In this case, the plurality of third flux barrier sections 53a may be arranged side by side in the radial direction or in the circumferential direction.

In a certain state where the circumferential center of the second magnet is arranged at the same circumferential position as the circumferential center of a certain tooth, the third flux barrier portion may be located radially inward of any other tooth, provided that the other tooth is different from the certain tooth. In a certain state, the third flux barrier portion may be located radially inward of a tooth located one tooth away from the certain tooth in the circumferential direction, or may be located radially inward of a tooth located three or more teeth away from the certain tooth in the circumferential direction. The third flux barrier portion may be located radially inward of any portion of the other tooth.

The shape of the recesses provided in the rotor core is not particularly limited. The number of recesses is not particularly limited. For example, in each magnetic pole portion 70 of the above-mentioned embodiment, only one of the recesses 22a and 22b may be provided, or three or more recesses 22a and 22b may be provided. No recesses may be provided.

The rotating electric machine to which the present invention is applied is not limited to a motor, and may be a generator. In this case, the rotating electric machine may be a three-phase AC generator. The use of the rotating electric machine is not particularly limited. The rotating electric machine may be mounted, for example, on a vehicle, or on equipment other than a vehicle. The number of poles and the number of slots of the rotating electric machine are not particularly limited. The coils in the rotating electric machine may be configured in any winding method. The configurations described above in this specification can be combined as appropriate within a range that does not contradict each other.

The usefulness of the present invention was verified by performing a simulation using Examples 1 to 4 and a comparative example. Examples 1 to 4 were configured similarly to the rotating electric machine 1 of the above-described embodiment. In Examples 1 to 4, the circumferential distance L1 between the first flux barrier section and the second flux barrier section arranged on either side of the third flux barrier section was set to 5.81 mm. In Examples 1 to 4, the radius r of the rotor core was set to 59.2 mm.

In Example 1, the radial distance L3 from the outer peripheral surface of the rotor core to the center of the third flux barrier portion was set to 2.2 mm. In Example 2, the distance L3 was set to 2.6 mm. In Example 3, the distance L3 was set to 3.0 mm. In Example 4, the distance L3 was set to 3.4 mm.

In Example 1, the circumferential position of the center of the third flux barrier section was set to a position where the circumferential angle between the magnetic pole section on which the third flux barrier section is provided and the magnetic pole section adjacent to the magnetic pole section in the circumferential direction is 9.2°. Hereinafter, the circumferential center between the magnetic pole section on which the third flux barrier section is provided and the magnetic pole section adjacent to the magnetic pole section in the circumferential direction is referred to as the "circumferential center between the magnetic pole sections". In Example 2, the circumferential position of the center of the third flux barrier section was set to a position where the circumferential angle between the magnetic pole sections is 9.0°. In Example 3, the circumferential position of the center of the third flux barrier section was set to a position where the circumferential angle between the magnetic pole sections is 8.8°. In Example 4, the circumferential position of the center of the third flux barrier section was set to a position where the circumferential angle between the magnetic pole sections is 8.6°. The comparative example differs from examples 1 to 4 only in that it does not have a third flux barrier section.

For each of Examples 1 to 4 and the Comparative Example, the 48th-order torque ripple was obtained by simulation. The 48th-order torque ripple is torque ripple caused by the 48th-order magnetic flux component. For Examples 1 to 4, the 48th-order torque ripple was obtained when the circumferential dimension W of the third flux barrier section was changed. These simulation results are shown in Figure 6. In Figure 6, the results of Example 1 are shown by a solid line TR1, the results of Example 2 are shown by a dashed line TR2, the results of Example 3 are shown by a dashed line TR3, and the results of Example 4 are shown by a dashed line TR4.

In FIG. 6, the horizontal axis indicates the circumferential dimension W [mm] of the third flux barrier section, and the vertical axis indicates the ratio TR of the 48th-order torque ripple obtained in each embodiment to the 48th-order torque ripple obtained in the comparative example. When the ratio TR is smaller than 1.0, it indicates that the 48th-order torque ripple obtained in each embodiment is smaller than the 48th-order torque ripple obtained in the comparative example. Since the comparative example does not have a third flux barrier section, the 48th-order torque ripple obtained in the comparative example is constant regardless of the circumferential dimension W of the third flux barrier section.

As shown by the solid line TR1 in FIG. 6, it was confirmed that in Example 1, the torque ripple ratio TR can be made smaller than 1.0 when the dimension W is in the range of 0.6 mm or more and 1.5 mm or less. As shown by the dashed line TR2 in FIG. 6, it was confirmed that in Example 2, the torque ripple ratio TR can be made smaller than 1.0 when the dimension W is in the range of 0.6 mm or more and 2.0 mm or less. As shown by the dashed line TR3 in FIG. 6, it was confirmed that in Example 3, the torque ripple ratio TR can be made smaller than 1.0 when the dimension W is in the range of 0.6 mm or more and 2.2 mm or less. As shown by the two-dot chain line TR4 in FIG. 6, it was confirmed that in Example 4, the torque ripple ratio TR can be made smaller than 1.0 when the dimension W is in the range of 0.8 mm or more and 2.4 mm or less. This confirmed that the torque ripple can be reduced by providing the third flux barrier section.

It was also confirmed that in each of Examples 1 to 4, the torque ripple ratio TR had a minimum value. This confirmed that the torque ripple had a minimum value depending on the circumferential dimension W of the third flux barrier section. Therefore, it was confirmed that the torque ripple can be more effectively reduced by setting the circumferential dimension W of the third flux barrier section to a value at which the torque ripple has a minimum value or a value close to that value.

In Example 1, for example, when the circumferential dimension W of the third flux barrier portion is about 0.9 mm, the torque ripple ratio TR is at a minimum value. In Example 1, it was confirmed that the torque ripple can be suitably reduced by setting the circumferential dimension W of the third flux barrier portion within a range of 0.6 mm to 1.1 mm, including 0.9 mm at which the ratio TR is at a minimum value. In Example 1, when the circumferential dimension W of the third flux barrier portion is within a range of 0.6 mm to 1.1 mm, the torque ripple ratio TR is 0.5 or less. In other words, it was confirmed that in Example 1, when the circumferential dimension W of the third flux barrier portion is within a range of 0.6 mm to 1.1 mm, the torque ripple can be suitably reduced to less than half compared to the comparative example.

In Example 2, for example, when the circumferential dimension W of the third flux barrier portion is about 1.35 mm, the torque ripple ratio TR is at a minimum value. In Example 2, it was confirmed that the torque ripple can be suitably reduced by setting the circumferential dimension W of the third flux barrier portion within a range of 1.0 mm to 1.7 mm, which includes the circumferential dimension W of about 1.35 mm at which the ratio TR is at a minimum value. In Example 2, when the circumferential dimension W of the third flux barrier portion is within a range of 1.0 mm to 1.7 mm, the torque ripple ratio TR is 0.5 or less. In other words, it was confirmed that in Example 2, when the circumferential dimension W of the third flux barrier portion is within a range of 1.0 mm to 1.7 mm, the torque ripple can be suitably reduced to less than half compared to the comparative example.

In Example 3, for example, when the circumferential dimension W of the third flux barrier portion is about 1.55 mm, the torque ripple ratio TR is at a minimum value. In Example 3, it was confirmed that the torque ripple can be suitably reduced by setting the circumferential dimension W of the third flux barrier portion within a range of 1.2 mm to 1.8 mm, including the circumferential dimension W of about 1.55 mm at which the ratio TR is at a minimum value. In Example 3, when the circumferential dimension W of the third flux barrier portion is in a range of 1.2 mm to 1.8 mm, the torque ripple ratio TR is 0.5 or less. In other words, it was confirmed that in Example 3, when the circumferential dimension W of the third flux barrier portion is in a range of 1.2 mm to 1.8 mm, the torque ripple can be suitably reduced to less than half compared to the comparative example.

In Example 4, for example, when the circumferential dimension W of the third flux barrier portion is about 1.8 mm, the torque ripple ratio TR becomes a minimum value. In Example 4, it was confirmed that the torque ripple can be suitably reduced by setting the circumferential dimension W of the third flux barrier portion within a range of 1.4 mm or more and 2.1 mm or less, including about 1.8 mm at which the ratio TR becomes a minimum value. In Example 4, when the circumferential dimension W of the third flux barrier portion is within a range of 1.4 mm or more and 2.1 mm or less, the torque ripple ratio TR is 0.5 or less. In other words, it was confirmed that in Example 4, when the circumferential dimension W of the third flux barrier portion is within a range of 1.4 mm or more and 2.1 mm or less, the torque ripple can be suitably reduced to half or less compared to the comparative example. The minimum value of the torque ripple ratio TR in Example 4 is smaller than the minimum value of the torque ripple ratio TR in Examples 1 to 3.

From the results of Examples 1 to 4, it was confirmed that, when the circumferential dimension W of the third flux barrier portion is within a range of about 0.6 mm or more and 2.1 mm or less, the torque ripple can be suitably reduced by adjusting the radial position of the center of the third flux barrier portion. When the circumferential dimension W of the third flux barrier portion is 0.6 mm or more and 2.1 mm or less, the ratio of the circumferential dimension W of the third flux barrier portion to the radius r of the rotor core is 0.010 or more and 0.035 or less. When the circumferential dimension W of the third flux barrier portion is 0.6 mm or more and 2.1 mm or less, the ratio of the circumferential dimension W of the third flux barrier portion to the circumferential distance L1 between the first flux barrier portion and the second flux barrier portion is 0.10 or more and 0.36 or less. From these, it was confirmed that the torque ripple can be suitably reduced by setting the ratio of the dimension W to each value within these ranges.

From the results of Examples 1 to 4, it was confirmed that the circumferential dimension W of the third flux barrier portion when the torque ripple ratio TR is at a minimum value increases as the radial distance L3 from the outer peripheral surface of the rotor core to the center of the third flux barrier portion increases. In other words, it was confirmed that by adjusting the distance L3, it is possible to adjust the range of the circumferential dimension W of the third flux barrier portion in which torque ripple can be suitably reduced.

In Examples 2, 3, and 4, it was confirmed that the torque ripple ratio TR is 0.5 or less when the circumferential dimension W of the third flux barrier portion is 1.38 mm or more and 1.7 mm or less. In Examples 2, 3, and 4, the radial distance L3 from the outer peripheral surface of the rotor core to the center of the third flux barrier portion is 2.6 mm or more and 3.4 mm or less. In other words, it was confirmed that the torque ripple can be suitably reduced when the radial distance L3 from the outer peripheral surface of the rotor core to the center of the third flux barrier portion is 2.6 mm or more and 3.4 mm or less, and the circumferential dimension W of the third flux barrier portion is 1.38 mm or more and 1.7 mm or less. From the above, the usefulness of the present invention was confirmed.

1... rotating electric machine, 10... rotor, 20... rotor core, 22a, 22b... recess, 30... accommodation hole, 40... magnet, 41a, 41b... first magnet, 42... second magnet, 51a, 51b, 51c, 51d... first flux barrier section, 52a, 52b... second flux barrier section, 53a, 53b... third flux barrier section, 60... stator, 61... stator core, 62... core back, 63, 66A, 66B, 66C, 66D, 66E, 66F... teeth, 65... coil, J... central axis

Claims (10)

A rotor rotatable about a central axis;
a stator positioned radially outward of the rotor;
Equipped with
The rotor is
A rotor core having a plurality of receiving holes;
A plurality of magnets respectively accommodated inside the plurality of accommodation holes;
having
The stator includes:
a stator core including an annular core back surrounding the rotor core and a plurality of teeth extending radially inward from the core back and arranged at intervals in a circumferential direction;
A plurality of coils attached to the stator core;
having
The plurality of magnets include
A pair of first magnets are arranged at intervals in the circumferential direction and extend in directions that move away from each other in the circumferential direction from the radially inner side toward the radially outer side as viewed in the axial direction;
a second magnet disposed at a circumferential position between the pair of first magnets radially outward of the radial inner ends of the pair of first magnets and extending in a direction perpendicular to the radial direction as viewed in the axial direction;
Including,
The rotor core is
a pair of first flux barrier sections disposed on either side of each of the first magnets in a direction in which each of the first magnets extends as viewed in the axial direction;
a pair of second flux barrier sections disposed on either side of the second magnet in a direction in which the second magnet extends as viewed in the axial direction;
a third flux barrier section disposed at least one of a circumferential direction between a first flux barrier section located radially outward of a pair of first flux barrier sections disposed to sandwich one of the pair of first magnets and one of the pair of second flux barrier sections, and a circumferential direction between a first flux barrier section located radially outward of a pair of first flux barrier sections disposed to sandwich the other of the pair of first magnets and the other of the pair of second flux barrier sections;
having
in a state in which a circumferential center of the second magnet is disposed at the same circumferential position as a circumferential center of one of the teeth, the third flux barrier portion is located radially inward of another of the teeth ,
A rotating electric machine, in which, in the certain state, the first flux barrier portion located radially outward of a pair of first flux barrier portions arranged on either side of the first magnet is located radially inward of a portion of the other tooth that is farther from the circumferential center of the second magnet, and the third flux barrier portion is located radially inward of a portion of the other tooth that is closer to the circumferential center of the second magnet . The rotating electric machine according to claim 1, wherein the third flux barrier section is provided both circumferentially between a first flux barrier section located radially outward among a pair of the first flux barrier sections arranged to sandwich one of the pair of first magnets and one of the pair of second flux barrier sections, and between a first flux barrier section located radially outward among a pair of the first flux barrier sections arranged to sandwich the other of the pair of first magnets and the other of the pair of second flux barrier sections. The rotating electric machine according to claim 1 or 2, wherein the other tooth is a tooth arranged two teeth away from the one tooth in the circumferential direction. The rotating electric machine according to claim 3, wherein in the certain state, at least some of the teeth arranged adjacent to each other in the circumferential direction between the certain tooth and the other tooth are located radially outside the second magnet. The rotor core has a recess recessed radially inward from an outer circumferential surface of the rotor core,
The rotating electric machine according to claim 1 , wherein in the certain state, the recess is disposed on a side farther away from a circumferential center of the second magnet than a circumferential center of the other one of the teeth. The rotating electric machine according to claim 5 , wherein in the certain state, at least a portion of the recess is located radially inward of the other one of the teeth. The rotating electric machine according to claim 5 , wherein the recess is located radially outward of a first flux barrier portion located radially outward of the pair of first flux barrier portions. The rotating electric machine according to claim 1 , wherein a circumferential dimension of the third flux barrier portion is not less than 0.6 mm and not more than 2.1 mm. A three-phase AC rotating electric machine,
9. The rotating electric machine according to claim 1, wherein the number of slots is N×6, where N is the number of poles. The rotating electric machine according to claim 1 , wherein the coil is a distributed winding and full-pitch winding.

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