ROTOR CORE, ROTOR, AND ROTATING ELECTRIC MACHINE

Abstract

According to the present invention, the positions of opening-end forward-side corner parts (1131a, 1131c) are located on the rearward side from reference positions (831a, 831b) in the rotation direction of a rotor core (811), in a cross section of the rotor core.

Description

[Technical field]

[0001] The present invention relates to a rotor core, a rotor, and a rotating electric machine. This application claims priority based on Japanese Patent Application No. 2021-185697 filed on November 15, 2021, the contents of which are incorporated herein by reference in their entirety. [Background technology]

[0002] In a rotating electric machine with embedded permanent magnets, such as an interior permanent magnet synchronous motor (IPMSM), a flux barrier is formed near the permanent magnet while a permanent magnet is embedded in the rotor core. The flux barrier is formed to control the flow of magnetic flux in the rotating electric machine. The flux barrier can improve the characteristics of the rotating electric machine. Patent Document 1 describes that a flux barrier is provided in a magnet hole in which a permanent magnet is provided. The flux barrier is provided on both the outer circumferential side and the inner circumferential side of the permanent magnet. Patent Document 1 also describes that the flux barrier on the outer circumferential side is opened on the outer circumferential side of the rotor core. Patent Document 1 also describes that the curvature of the flux barrier on the inner circumferential side is determined so as to reduce stress in the bridge portion between the magnets between the flux barriers on the inner circumferential side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-57984 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the technology described in Patent Document 1, the configuration of the flux barrier on the outer periphery is determined only from the viewpoint of suppressing short-circuiting of magnetic flux via the outer periphery of the rotor core, and therefore the torque of the rotor cannot be sufficiently improved.

[0005] The present invention has been made in consideration of the above problems, and has an object to increase the torque of the rotor. [Means for solving the problem]

[0006] Rotor core of the present invention First examplea rotor core including a soft magnetic material portion formed using a soft magnetic material and having at least one magnet hole per pole, the magnet hole having a space serving as a front flux barrier and a space serving as a rear flux barrier on both sides in a left-right direction perpendicular to a magnetization direction of the permanent magnet and a direction parallel to a rotation axis that is the center of rotation for a permanent magnet installed in the magnet hole, at least one of the spaces serving as the front flux barrier and the rear flux barrier has an open end that is opened on an outer circumferential surface of the rotor core, in a cross section perpendicular to the rotation axis, a position of an open end front corner portion of at least one of the open ends installed at the same pole of the rotor is located rearward in the rotation direction of the rotor core with respect to a reference position for the magnet hole having the open end, and in the cross section, the open end front corner portion is located rearward in the circumferential direction of the rotor core of at least one of the open ends installed at the same pole of the rotor a reference position for the magnet hole having the open end in the cross section is a position of an intersection between a permanent magnet reference end, which is one of the ends of the permanent magnets installed in the magnet hole and located closest to the open end, and a straight line passing through the rotation axis and the outer peripheral surface of the rotor core; the permanent magnet reference end of the permanent magnet located closest to the open end in the cross section is an end of the permanent magnet that is located farthest in the circumferential direction from a straight line passing through the rotation axis and a center position in the circumferential direction of one pole region including the permanent magnet, and the distance in the circumferential direction from a straight line passing through the rotation axis and a center position in the circumferential direction of one pole region including the permanent magnet located closest to the open end is a distance determined on the side where the open end exists, of the front side and the rear side in the rotation direction of the rotor core. In the cross section, the positions of the open end front corner portions of all the open ends installed on the same pole of the rotor are located rearward in the rotation direction of the rotor core from the reference position for the magnet hole having the open end. do. A second example of a rotor core of the present invention is a rotor core including a soft magnetic material portion formed using a soft magnetic material and having at least one magnet hole per pole, the magnet hole having a space serving as a front side flux barrier and a space serving as a rear side flux barrier on both sides in a left-right direction perpendicular to a magnetization direction of the permanent magnet and a direction parallel to a rotation axis that is a center of rotation with respect to a permanent magnet installed in the magnet hole, at least one of the spaces serving as the front side flux barrier and the rear side flux barrier has an open end that is opened on an outer circumferential surface of the rotor core, in a cross section perpendicular to the rotation axis, the front side flux barrier is located forward of the rear side flux barrier in a rotation direction of the rotor core, in the cross section perpendicular to the rotation axis, the position of an open end front corner portion of at least one of the open end portions installed at the same pole of the rotor in the cross section is located rearward of a reference position for the magnet hole having the open end, and in the cross section, the open end front corner portion is located forward of at least one of the open end portions installed at the same pole of the rotor in a rotation direction of the rotor core. Of the two corners of the open end in the circumferential direction of the rotor core, the open end is the front corner in the rotation direction of the rotor core, and in the cross section, a reference position for the magnet hole having the open end is the position of the intersection of a permanent magnet reference end, which is one of the ends of the permanent magnets installed in the magnet hole and located closest to the open end, with the rotation axis, and the outer circumferential surface of the rotor core, and the permanent magnet reference end of the permanent magnet located closest to the open end in the cross section is one of the ends of the permanent magnet. the soft magnetic material portion is an end portion located at a farthest distance in the circumferential direction from a line passing through the rotation axis and a center position in the circumferential direction of one pole region including the permanent magnet, and the distance in the circumferential direction from a line passing through the rotation axis and a center position in the circumferential direction of one pole region including the permanent magnet located closest to the open end is a distance determined on the side where the open end exists, between the front side and the rear side in the rotation direction of the rotor core, and the soft magnetic material portion is a recessed portion different from the space serving as the flux barrier,The rotor core further includes a recess having an open end that is open on the outer circumferential surface of the rotor core, and the recess is located at a position facing, with a gap, a tooth of a stator core other than a tooth having the lowest magnetic flux density among the teeth of the stator core that are installed at a position facing, with a gap, the outer circumferential surface of the rotor core. A third example of a rotor core of the present invention is a rotor core formed using a soft magnetic material and including a soft magnetic material portion having at least one magnet hole per pole, the soft magnetic material portion having a recessed portion on its outer peripheral surface, the magnet hole having a first end and a second end in a left-right direction perpendicular to the magnetization direction of a permanent magnet installed in the magnet hole and a direction parallel to the rotation axis that is the center of rotation, at least one of the first end and the second end is an open end that is open, the recessed portion is located at a position different from the open end, and the recessed portion is located at a position opposite, with a gap, to a tooth of a stator core that is different from the tooth having the lowest magnetic flux density among the teeth of the stator core that are installed at a position opposite, with a gap, to the outer peripheral surface of the rotor core. The rotor of the present invention includes the rotor core and a plurality of permanent magnets disposed in the rotor core. A rotating electric machine according to the present invention includes the rotor and a stator. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing an example of the basic shape of an IPMSM. [Diagram 2] FIG. 2 is a view showing a cross section of the rotor of the IPMSM shown in FIG. [Diagram 3] FIG. 3 is a diagram showing an example of an optimum shape of the IPMSM. [Figure 4A] FIG. 4A is a diagram showing a first analysis result of a magnetic flux density vector in an IPMSM having an optimum shape. [Figure 4B] FIG. 4B is a diagram illustrating an example of an outline of the magnetic flux flow in the first analysis result. [Figure 5A] FIG. 5A is a diagram showing a second analysis result of the magnetic flux density vector in an IPMSM with an optimal shape. [Figure 5B] FIG. 5B is a diagram illustrating an example of an outline of the magnetic flux flow in the second analysis result. [Figure 6A] FIG. 6A is a diagram showing an example of magnetic flux density vectors in an IPMSM of the basic shape when the residual magnetic flux density of a permanent magnet is 0.4 T. [Figure 6B] FIG. 6B is a diagram illustrating an example of an outline of the flow of magnetic flux in an IPMSM of the basic shape when the residual magnetic flux density of the permanent magnet is 0.4 T. [Figure 7A] FIG. 7A is a diagram showing an example of magnetic flux density vectors in an IPMSM of the basic shape when the residual magnetic flux density of a permanent magnet is 1.0 T. [Figure 7B] FIG. 7B is a diagram illustrating an example of an outline of the flow of magnetic flux in an IPMSM of the basic shape when the residual magnetic flux density of the permanent magnet is 1.0 T. [Figure 8] FIG. 8 is a diagram illustrating an example of a configuration of the IPMSM according to the embodiment. [Figure 9]FIG. 9 is a diagram illustrating an example of a rotor cross section according to the embodiment. [Figure 10] FIG. 10 is a diagram illustrating an example of a configuration of a rotor core according to an embodiment. [Figure 11A] FIG. 11A is an enlarged view of a portion of the rotor core shown in FIG. [Figure 11B] FIG. 11B is a diagram showing a first modified example of the configuration of the rotor core. [Figure 11C] FIG. 11C is a diagram showing a second modified example of the configuration of the rotor core. [Figure 12A] FIG. 12A is a diagram showing a first example of the configuration of a rotor for which an analysis is performed. [Figure 12B] FIG. 12B is a diagram showing a second example of the configuration of the rotor for which the analysis is performed. [Figure 12C] FIG. 12C is a diagram showing a third example of the configuration of the rotor for which the analysis is performed. [Figure 12D] FIG. 12D is a diagram showing a fourth example of a rotor configuration for which an analysis is performed. [Figure 12E] FIG. 12E is a diagram showing a fifth example of the configuration of the rotor for which the analysis is performed. [Figure 12F] FIG. 12F is a diagram showing a sixth example of a rotor configuration for which an analysis is performed. [Figure 12G] FIG. 12G is a diagram showing a seventh example of a rotor configuration for which an analysis is performed. [Figure 12H] FIG. 12H is a diagram showing an eighth example of a rotor configuration for which analysis is performed. [Figure 12I] FIG. 12I is a diagram showing a ninth example of a rotor configuration for which an analysis is performed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In addition, the fact that the comparison objects are the same in terms of length, position, size, interval, etc. includes not only that the comparison objects are exactly the same, but also that the comparison objects are different within the scope of the invention. For example, the fact that the comparison objects are the same includes that the comparison objects are different within the range of tolerances determined at the time of design. In addition, in each figure, the xyz coordinates indicate the relationship of the orientation in each figure. In the xyz coordinates, a symbol with a black circle (●) in a white circle (◯) indicates an arrow line in which the direction from the back side to the front side of the paper is the positive direction. In addition, in each figure, when there are multiple identical components, the symbols of some of the multiple components are omitted for convenience of notation. In addition, hereinafter, the multiple components will be described using the components with symbols among the multiple components as necessary.

[0009] (background) In JP 2021-114099 A, the present inventors proposed a method for designing the shapes of various cores, including the rotor core of an IPMSM. Therefore, the present inventors used this method to search for a shape of the rotor core that contributes to improving torque. The embodiments of the present invention described below are based on the results. Below, the results are described, and the process leading to the embodiments of the present invention described below is described.

[0010] In the method described in the specification of JP 2021-114099 A, it is necessary to set the basic shape of the design target element. In this section, a case where the shapes of the flux barriers 113a to 113b and 114a to 114b in the rotor 110 of the IPMSM 100 shown in Fig. 1 are set as the basic shape of the design target element is illustrated. Therefore, first, the IPMSM 100 shown in Fig. 1 will be described.

[0011] FIG. 1 illustrates an example in which the number of poles of the IPMSM100 is 8. In FIG. 1, the range indicated by the double-headed arrow labeled "1 pole" is the portion that constitutes 1 pole of the IPMSM100. When the number of poles of the IPMSM100 is n poles, the IPMSM100 generally has an n-fold rotational symmetry relationship with the rotation axis 0 of the IPMSM100 as the axis of rotational symmetry. n is an integer of 2 or more, and in the example illustrated in FIG. 1, n is 8 (n=8). FIG. 1 illustrates one of four regions obtained by dividing a cross section of the IPMSM100 perpendicular to the rotation axis 0 into four equal parts, and illustrates the region of the IPMSM100 that constitutes two poles of the rotor 110. These four regions generally have a 4-fold (=8 poles÷2) rotational symmetry relationship with the rotation axis 0 of the IPMSM100 as the axis of rotational symmetry. Therefore, in FIG. 1, by rotating the area shown in FIG. 1 by 90° with the center line of IPMSM100 as the rotation axis 0, the overall configuration of the cross section of IPMSM100 when cut perpendicular to the rotation axis 0 of IPMSM100 can be obtained.

[0012] As shown in FIG. 1, the IPMSM 100 includes a rotor 110 and a stator 120. Stator 120 includes stator core 121 and a stator coil (not shown), and is for generating a rotating magnetic field. Note that the stator coil included in stator 120 is not shown in Fig. 1. However, the stator coil (not shown) is disposed in each slot 122 of stator core 121 (as described above, for convenience of notation, only one slot is marked in Fig. 1).

[0013] The rotor 110 rotates about the rotation axis 0 of the IPMSM 100. In this section, an example is shown in which the rotor 110 rotates in the direction of the arrow next to the "rotation direction" in Fig. 1 (counterclockwise as viewed from the page). Note that the rotation axis 0 of the rotor 110 and the rotation axis 0 of the IPMSM 100 coincide with each other. The rotor 110 includes a rotor core 111 and a plurality of permanent magnets per pole (two permanent magnets 112a to 112b in the example shown in FIG. 1). The rotor core 111 is made of a soft magnetic material.

[0014] Here, a case where multiple permanent magnets 112 are installed in rotor core 111 per pole is illustrated. Therefore, multiple magnet holes are formed in rotor core 111 per pole along a direction parallel to the rotation axis 0 of rotor core 111 (in the following description, the direction parallel to the rotation axis 0 will be referred to as the z-axis direction as necessary). The magnet holes are through holes penetrating in the z-axis direction. Multiple permanent magnets 112a-112b are installed (embedded) in rotor core 111 by being inserted into the magnet holes formed in rotor core 111. As described above, FIG. 1 shows a region of IPMSM 100 that constitutes two poles of rotor 110. In FIG. 1, two permanent magnets 112a-112b are embedded per pole. Therefore, a total of 16 permanent magnets are embedded in rotor core 111. As described above, in FIG. 1, for convenience of notation, only the portion constituting one pole of rotor 110 is labeled with a reference numeral, and the reference numerals for the portions constituting the other seven poles of rotor 110 are omitted.

[0015] In the magnet holes formed in the rotor core 111, the spaces where the permanent magnets 112a to 112b are not present become the flux barriers 113a to 113b and 114a to 114b. The flux barriers 113a to 113b and 114a to 114b are regions where the magnetic flux does not pass, or regions where the magnetic flux passes less easily than the regions around the flux barriers 113a to 113b and 114a to 114b. Here, a case where no tangible object exists in the flux barriers 113a to 113b and 114a to 114b is illustrated (i.e., a case where the flux barriers 113a to 113b and 114a to 114b are voids (areas of air) is illustrated). However, even if non-magnetic objects are installed in the flux barriers 113a to 113b and 114a to 114b, the same results as those shown in FIGS. 4A to 7B described later can be obtained.

[0016] In the following description, a cross section of rotor 110 taken perpendicular to the rotation axis 0 of IPMSM 100 (rotor 110) will be referred to as a rotor cross section as necessary. Fig. 2 is a diagram showing a rotor cross section for one pole of IPMSM 100 shown in Fig. 1. Note that in Fig. 2, hatching indicating a cross section is omitted to avoid making the positions indicated by the respective symbols unclear.

[0017] In FIG. 2, magnetic flux flows in and out of the magnetic pole faces 201a-201b and 201c-201d of the permanent magnets 112a-112b. Also, in FIG. 2, the direction perpendicular to the magnetic pole faces 201a-201b and 201c-201d is the magnetization direction Dm of the permanent magnets 112a-112b. In the following description, the directions on both the left and right sides of the magnetization direction Dm of the permanent magnet 112 at the center of the permanent magnets 112a-112b in the rotor cross section will be referred to as left and right directions Ds as necessary. The left and right directions Ds are perpendicular to the magnetization direction Dm of the permanent magnet 112 and the direction parallel to the rotation axis 0 of the IPMSM 100. The flux barriers 113a-113b and 114a-114b are formed on both sides of the left and right direction Ds of the permanent magnets 112a-112b.

[0018] In the following description, of the flux barriers 113a-113b, 114a-114b, those flux barriers positioned on the outer periphery side of the permanent magnets 112a-112b in the left-right direction Ds will be referred to as outer periphery-side flux barriers 113a-113b as necessary. Also, of the flux barriers 113a-113b, 114a-114b, those flux barriers positioned on the inner periphery side of the permanent magnets 112a-112b in the left-right direction Ds will be referred to as inter-magnet flux barriers 114a-114b as necessary.

[0019] The bridge portions 116a-116b are (narrow) regions that connect the soft magnetic material regions of the rotor core 111 in the circumferential direction. The circumferential direction is the direction around the outer circumferential surface 115 of the rotor 110 (rotor core 111) (directions parallel and anti-parallel to the rotation direction of the rotor 110 (rotor core 111)). The bridge portion 117a is a (narrow) region that connects the soft magnetic material regions of the rotor core 111 in the radial direction of the IPMSM 100. In the following description, of the bridge portions 116a-116b, 117a, the bridge portions 116a-116b located on the outer circumferential side in the left-right direction Ds (on the outer circumferential side in the radial direction of the IPMSM 100) are referred to as outer circumferential bridge portions as necessary. Among the bridge portions 116a-116b, 117a, the bridge portion 117a located on the inner circumferential side in the left-right direction Ds (the inner circumferential side in the radial direction of the IPMSM 100) than the permanent magnets 112a-112b will be referred to as the inter-magnet bridge portion 117a as necessary. In the example shown in Fig. 2, the outer circumferential side bridge portions 116a-116b are regions of a soft magnetic material located between the outer circumferential side flux barriers 113a-113b and the outer circumferential surface 115 of the rotor core 111. Furthermore, the inter-magnet bridge portion 117a is a region of a soft magnetic material located between the inter-magnet flux barriers 114a-114b.

[0020] The bridge portions 116a-116b, 117a are intended to prevent the magnetic flux flowing out from the permanent magnets 112a-112b from returning to the permanent magnets 112. In the bridge portions 116a-116b, 117a, the area of ​​a cross section perpendicular to the direction of travel of the magnetic flux is smaller than that of other regions. Therefore, the magnetic resistance of the bridge portions 116a-116b, 117a is larger than that of other regions of the soft magnetic material constituting the rotor core 111. Therefore, by providing the bridge portions 116a-116b, 117a, it is possible to prevent the magnetic flux flowing out from the permanent magnets 112a, 112b from returning to the permanent magnets 112. The bridge portions 116a-116b, 117a are present to ensure the mechanical strength of the rotor core 111. It has been common technical knowledge among those skilled in the art that the magnetic flux passing through the bridge portions 116a-116b and 117a flows back to the permanent magnets 112a-112b and therefore hardly contributes to the torque of the rotor 110. In the following explanation, it is assumed that the magnetic flux flows out from one pole face of the permanent magnet, passes through the bridge portion, and then flows to the permanent magnet. stone The magnetic flux returning (returning) to the other magnetic pole face is referred to as return flux, as necessary.

[0021] The present inventors designed the shape of the rotor core 111 by the method described in the specification of JP 2021-114099 A. At that time, the flux barriers 113a to 113b and 114a to 114b shown in FIG. 1 and FIG. 2 were set as design target elements (elements whose shape is changed from the basic shape). In addition, the permanent magnet 112 was set as a predetermined core element (element whose shape is not changed) other than the design target element. In addition, the residual magnetic flux density of the permanent magnet 112 was set to 0.4 T. Note that the residual magnetic flux density of the permanent magnet 112 is predetermined, for example, according to the specifications of the permanent magnet 112. In addition, the excitation current flowing through the stator coil (not shown) was set to a three-phase AC current with a peak value of 20 A and a frequency of 50 Hz. In addition, the advance angle was set to 30°. In addition, the optimization condition in the algorithm for the optimization problem was set to maximize the value of the average torque of the rotor 110, ignoring the stress generated in the rotor core 111 due to the centrifugal force received by the rotor 110 as the rotor 110 rotates. That is, the shape shown in FIG. 3 is an optimal shape in the case where excessive stress generated in the rotor core 111 is permitted. Therefore, the shape shown in FIG. 3 is a shape in which whether or not the shape of the rotor core 111 is a feasible shape is not taken into consideration if the optimization conditions are satisfied. In the following description, in order to distinguish from the IPMSM having a shape designed in this manner, the IPMSM100 shown in FIG. 1 will be referred to as the IPMSM100 of the basic shape as necessary. FIG. 3 is a diagram showing an example of the configuration of the IPMSM100 optimized from the IPMSM100 of the basic shape so that the value of the average torque of the rotor 110 is maximized by the method described in the specification of JP 2021-114099 A. In the following description, the IPMSM100 shown in FIG. 3 will be referred to as the IPMSM100 of the optimal shape as necessary. Below, the IPMSM100 shown in FIG. 3 will be described based on the knowledge obtained by the present inventors from the IPMSM100 of the optimal shape.

[0022] ((First Finding)) As described above, the optimum shape shown in FIG. 3 is a shape in which excessive stress occurring in the rotor core 111 is permitted. The outer periphery bridge portions 116a-116b are made of a soft magnetic material. Therefore, the magnetic permeability of air is smaller than that of the outer periphery bridge portions 116a-116b, and therefore the magnetic resistance of air is larger than that of the outer periphery bridge portions 116a-116b. Therefore, in the IPMSM 100 having the optimum shape shown in FIG. 3, the outer periphery flux barriers 113c-113d are formed so that (part of) the outer periphery flux barriers 113a-113b shown in FIG. 1 and FIG. 2 reach the outer periphery surface 115 of the rotor core 111 and are open (communicating) to the outside. In other words, the outer periphery flux barriers 113c-113d form open ends on the outer periphery surface 115 of the rotor core 111 (soft magnetic material portion). The longitudinal direction of the open end is parallel to the z-axis direction, the lateral direction of the open end is the circumferential direction, and the open end is connected to the outside. The open end is an open end, and is an imaginary surface, not an actual surface. In the IPMSM 100 having the basic shape shown in FIG. 2, the outer periphery bridge portions 116a to 116b are present. Therefore, the outer periphery flux barriers 113a to 113b do not reach the outer periphery surface 115 and are closed. In this respect, it is different from FIG. 2 and FIG. 3. On the other hand, in the IPMSM 100 having the optimum shape shown in FIG. 3, the outer periphery flux barriers 113c to 113d reach the outer periphery surface 115 of the rotor core 111 and are open. From this, it can be said that most of the magnetic flux passing through the outer periphery bridge portions 116a to 116b shown in FIG. 1 and FIG. 2 is return magnetic flux.

[0023] The outer circumferential flux barriers 113c to 113d shown in Fig. 3 reduce the return flux. In addition, the inventors have noticed that the open ends 310c to 310d of the outer circumferential flux barriers 113c to 113d are shifted toward the rear side in the rotation direction of the rotor core 111 (the opposite side to the rotation direction) as shown in Fig. 3. c We wondered whether ~113d might play a role other than that of reducing the return flux, which has been conventionally understood as common technical knowledge.

[0024] Therefore, the inventors checked the results of electromagnetic field analysis (magnetic flux density vectors) of the IPMSM 100 having the optimal shape shown in Fig. 3, in the vicinity of the outer periphery flux barriers 113c-113d. In Fig. 3, r and θ respectively represent the radius and the deflection angle in polar coordinates (circular coordinates). In Fig. 3, the position of the rotation axis 0 in the cross section of rotor core 111 when cut perpendicularly to the rotation axis 0 of rotor core 111 is taken as the origin 0 of the polar coordinates. Also, the direction from origin 0 toward the outside is the positive radial direction (radial direction of IPMSM 100), and the counterclockwise direction (rotation direction) toward the page is the positive deflection angle. The outside refers to the rotor core 1 11 outer surfaces 115 This is the side where it exists.

[0025] 4A and 4B are diagrams illustrating a first result of an electromagnetic field analysis of the IPMSM 100 having an optimal shape. FIG. 4A is a diagram illustrating an example of a magnetic flux density vector in the IPMSM 100 having an optimal shape. FIG. 4B is a diagram illustrating an example of a schematic flow of magnetic flux in the IPMSM 100 having an optimal shape near the outer circumferential surface 115 of the rotor core 111. In FIG. 4A, the magnetic flux density vector is represented by an arrow line having a density according to its size. However, in FIG. 4A, due to the convenience of notation, the characteristics of the magnetic flux density vector cannot be clearly shown. Therefore, for convenience of explanation, FIG. 4B shows a schematic flow of magnetic flux necessary for explanation among the magnetic flux in the IPMSM 100 having an optimal shape. In FIG. 4B, "N" and "S" shown in the permanent magnets 112a to 112b indicate the magnetic poles (N pole and S pole) of the rotor 110. Therefore, the magnetic pole faces 201a and 201c of the permanent magnets 112a and 112b are N pole faces, and the magnetic pole faces 201b and 201d are S pole faces.

[0026] 4B, the arrows in the teeth 123a to 123d of the stator core 121 indicate magnetic flux generated in the teeth 123a to 123d of the stator core 121 at the time when the positional relationship between the rotor 110 and the stator 120 is as shown in FIG. 4A and FIG. 4B. Specifically, the arrows in the teeth 123a to 123b of the stator core 121 indicate that magnetic flux is generated in the teeth 123a to 123b of the stator core 121 in a direction from the rotation axis 0 of the IPMSM 100 toward the outside along the radial direction of the IPMSM 100. On the other hand, the arrows in the teeth 123c to 123d of the stator core 121 indicate that magnetic flux is generated in the teeth 123c to 123d of the stator core 121 in a direction toward the rotation axis 0 of the IPMSM 100 along the radial direction of the IPMSM 100. The number of arrows indicates the relative magnitude relationship of the magnetic flux amount (magnetic flux density) in the teeth 123c to 123d of the stator core 121. The greater the number of arrows, the greater the magnetic flux amount (higher magnetic flux density). However, the ratio of the magnetic flux amount (magnetic flux density) does not necessarily match the ratio of the number of arrows. The instantaneous value of the torque of the rotor 110 changes while the rotor 110 makes one rotation. The time when the positional relationship between the rotor 110 and the stator 120 is as shown in FIG. 4A and FIG. 4B is the time when the instantaneous value of the torque of the rotor 110 is maximum.

[0027] In addition, in FIG. 4B, the arrow line extending from the rotor 110 (rotor core 111) to the stator 120 (stator core 121) indicates the direction of the magnetic flux flowing from the rotor 110 (rotor core 111) to the stator 120 (stator core 121). In addition, the arrow line extending from the stator 120 (stator core 121) to the rotor 110 (rotor core 111) indicates the direction of the magnetic flux flowing from the stator 120 (stator core 121) to the rotor 110 (rotor core 111). In FIG. 4B, for convenience of notation, the magnetic fluxes φ1, φ2, and φ3 represented by these arrow lines are all represented by a single arrow line. However, the magnetic flux amounts of the magnetic fluxes φ1, φ2, and φ3 are not necessarily the same.

[0028] The results shown in Fig. 4A and Fig. 4B are for the case where the rotor core 111 rotates counterclockwise on the paper. Therefore, of the two permanent magnets 112a and 112b with the same pole, the permanent magnet located on the front side in the direction of rotation (the side in the direction of rotation) is the permanent magnet 112a, and the permanent magnet located on the rear side is the permanent magnet 112b (see the arrows next to "front side" and "rear side" in Fig. 4B). In the following description, the permanent magnet 112a located on the front side in the direction of rotation is referred to as the front-side permanent magnet 112a as necessary. Also, the permanent magnet 112b located on the rear side behind the rotation is referred to as the rear-side permanent magnet 112b as necessary.

[0029] The outer circumferential flux barrier 113c reduces the return flux that flows from one magnetic pole face (e.g., N pole) of the front permanent magnet 112a to the other magnetic pole face (e.g., S pole) via the outer circumferential bridge portion 116a shown in FIG. 2. Similarly, the outer circumferential flux barrier 113 d This reduces the return magnetic flux that flows from one magnetic pole face (for example, the N pole) of the rear permanent magnet 112b to the other magnetic pole face (for example, the S pole) via the outer periphery bridge portion 116b shown in FIG.

[0030] The torque of the rotor 110 is determined by the radial component B of the magnetic flux density vector in the gap G between the rotor 110 (rotor core 111) and the stator 120 (stator core 121). r and the circumferential component B θ In the following description, the radial direction (the radial direction of the IPMSM 100) component will be referred to as the radial direction component as necessary. Therefore, when a polar coordinate system is defined as shown in FIG. 3, the radial direction component B of the magnetic flux density vector in the direction from the rotor 110 to the stator 120 is r and the circumferential component B θ are both positive and the direction of the magnetic flux density vector is inclined significantly with respect to the radial direction of the IPMSM 100, the torque of the rotor 110 becomes large.

[0031] 4B, magnetic flux φ1 directed from a region of outer circumferential surface 115 of rotor core 111 that is rearward of outer circumferential flux barrier 113c in the direction of rotation of IPMSM 100 to teeth 123a of stator core 121 is inclined significantly with respect to the radial direction of IPMSM 100. This is believed to be because open end 310c of outer circumferential flux barrier 113c is shifted rearward in the direction of rotation of rotor core 111 (opposite the direction of rotation).

[0032] From the above, the inventors have obtained a first finding that the torque of the rotor 110 can be increased by shifting the open end 310 of the outer periphery-side flux barrier 113 rearward in the rotation direction of the rotor core 111 (opposite the rotation direction). In the following description, the magnetic flux φ1 flowing from a region of the outer periphery surface 115 of the rotor core 111 that is rearward of the outer periphery-side flux barrier 113c in the rotation direction of the IPMSM 100 toward the teeth 123a of the stator core 121 will be referred to as the magnetic flux φ1 on the rear side of the outer periphery-side flux barrier 113c as necessary.

[0033] In addition, in FIG. 4B, the magnetic flux in the opposite direction to the magnetic flux φ1 on the rear side of the outer circumferential flux barrier 113c also contributes to an increase in the torque of the rotor 110. r and the circumferential component B θ are both negative.

[0034] ((Second finding)) The present inventors also noticed that recesses 118a, 119a are formed at positions different from outer periphery flux barriers 113c-113d in IPMSM 100 having the optimum shape shown in Fig. 3. Therefore, the present inventors checked the results of electromagnetic field analysis (magnetic flux density vectors) of IPMSM 100 having the optimum shape shown in Fig. 3 near recesses 118a, 119a.

[0035] When a polar coordinate system is defined as shown in FIG. 3, the radial component B of the magnetic flux density vector from the stator 120 to the rotor 110 is r and the circumferential component Bθ and are both negative and the direction of the magnetic flux density vector is inclined significantly with respect to the radial direction of the IPMSM 100, the torque of the rotor 110 becomes large.

[0036] As described above, the results of the electromagnetic field analysis shown in FIG. 4A are the results when the excitation current flowing through the stator coil (not shown) is a three-phase AC current. Therefore, a rotating magnetic field is generated in the IPMSM 100. Ta 1 The rotation period of stator core 10 (rotor core 111) is the same as the rotation period of the rotating magnetic field generated in stator core 121 (teeth 123). Therefore, the positional relationship between rotor core 111 and the rotating magnetic field does not change even when rotor core 111 rotates. Note that the excitation current used in the present application is not limited to a three-phase AC current.

[0037] 4B, recessed portion 118a faces teeth 123a, 123c (teeth 123a, 123c with two arrows) having a high magnetic flux density even when rotor core 111 rotates. Magnetic flux φ2 flowing from teeth 123c of stator core 121 toward a region on outer circumferential surface 115 of rotor core 111 that is further rearward in the direction of rotation of IPMSM 100 than recessed portion 118a is inclined with respect to the radial direction of IPMSM 100, and the radial component B of the magnetic flux density vector due to magnetic flux φ2 is r and the circumferential component B θ are both negative.

[0038] Therefore, magnetic flux φ2 flowing from teeth 123c of stator core 121 toward a region of outer peripheral surface 115 of rotor core 111 that is rearward of recessed portion 118a in the direction of rotation of IPMSM 100 contributes to an increase in the torque of rotor 110. In the following description, magnetic flux φ2 flowing from teeth 123c of stator core 121 toward a region of outer peripheral surface 115 of rotor core 111 that is rearward of recessed portion 118a in the direction of rotation of IPMSM 100 will be referred to as magnetic flux φ2 on the rear side of recessed portion 118a as necessary.

[0039] On the other hand, magnetic flux φ3 flowing from teeth 123c of stator core 121 toward a region of outer circumferential surface 115 of rotor core 111 that is forward of recessed portion 118a in the direction of rotation of IPMSM 100 is inclined with respect to the radial direction of IPMSM 100, and the radial component B of the magnetic flux density vector due to magnetic flux φ3 is r , circumferential component B θ are negative and positive, respectively. Therefore, magnetic flux φ3 flowing from teeth 123c of stator core 121 toward a region of outer circumferential surface 115 of rotor core 111 that is further forward in the direction of rotation of IPMSM 100 than recessed portion 118a does not contribute to an increase in the torque of rotor 110. In the following description, magnetic flux φ3 flowing from teeth 123c of stator core 121 toward a region of outer circumferential surface 115 of rotor core 111 that is further forward in the direction of rotation of IPMSM 100 than recessed portion 118a will be referred to as magnetic flux φ3 on the forward side of recessed portion 118a as necessary.

[0040] Therefore, if the size and position of recess 118a are determined so that magnetic flux φ2 on the rear side of recess 118a is larger than magnetic flux φ3 on the front side of recess 118a, the torque of rotor 110 can be increased.

[0041] 4B, recessed portion 119a faces teeth 123a, 123b (teeth 123a, 123b with two arrows) having a low magnetic flux density even when rotor core 111 rotates. Therefore, recessed portion 119a does not contribute to increasing the torque of rotor 110 as much as recessed portion 118a does. Furthermore, if the number of recessed portions is increased, the mechanical strength of rotor 110 (rotor core 111) may be reduced.

[0042] From the above, the inventors have reached a second insight that the torque of rotor 110 can be increased by providing recess 118a in a position facing teeth 123a, 123b, which have a magnetic flux density higher than the minimum magnetic flux density, in the region of outer circumferential surface 115 of rotor core 111.

[0043] Which of teeth 123a to 123d of stator core 121 has the lowest magnetic flux density is identified from the results of an electromagnetic field analysis such as that shown in FIG. 4A.

[0044] 4B, similarly to the magnetic flux φ2 on the rear side of the recess 118a, the magnetic flux in the opposite direction to the magnetic flux φ2 on the rear side of the recess 118a also contributes to an increase in the torque of the rotor 110. r and the circumferential component B θ This is because both are positive. Similarly to the magnetic flux φ3 on the front side of the recess 118a, the magnetic flux in the opposite direction to the magnetic flux φ3 on the front side of the recess 118a does not contribute to an increase in the torque of the rotor 110. r , circumferential component B θ becomes negative and positive, respectively.

[0045] ((Third Finding)) 1 and 2, inter-magnet bridge portion 117 is made of a soft magnetic material. Therefore, the magnetic permeability of air is smaller than that of inter-magnet bridge portion 117. Therefore, the magnetic resistance of air is larger than that of inter-magnet bridge portion 117. Therefore, all of the magnetic fields including inter-magnet bridge portion 117a shown in FIG. 1 and FIG. stoneIf the inter-magnet bridge portion is a flux barrier (gap portion), the area of ​​the magnetic material constituting the inter-magnet bridge portion is replaced with a gap portion. This replacement reduces the magnetic permeability of the area. Therefore, the magnetic resistance of the area increases. Therefore, according to the above-mentioned technical common sense, it is considered that the return magnetic flux is reduced. From this, the inventors predicted that not only the outer periphery bridge portions 116a-116b shown in FIG. 1 and FIG. 2 but also the inter-magnet bridge portion 117a would become a flux barrier (gap portion). However, the IPMSM 100 having the optimal shape shown in FIG. 3 showed a result different from this prediction. However, in the IPMSM 100 having the optimal shape shown in FIG. 3, the inter-magnet flux barriers 114a-114b shown in FIG. 1 and FIG. 2 are not connected, as in the inter-magnet flux barriers 114c-114d. That is, in the IPMSM 100 having the optimal shape shown in FIG. 3, a part of the inter-magnet bridge portion 117a shown in FIG. 1 and FIG. 2 remains, as in the inter-magnet bridge portion 117b. Thus, the optimal shape of the IPMSM100 shown in FIG. 3 turned out to be different from the prediction mentioned above.

[0046] 1 and 2, the outer periphery bridge portions 116a-116b are located closer to the stator 120 than the inter-magnet bridge portion 117a. Therefore, the magnetic flux passing through the outer periphery bridge portions 116a-116b is more likely to flow toward the stator 120 than the magnetic flux passing through the inter-magnet bridge portion 117a. outside It is considered that the magnetic flux passing through the circumferential bridge portions 116a-116b is less likely to become return magnetic flux than the magnetic flux passing through the inter-magnet bridge portion 117a. For this reason, it is considered that the magnetic flux toward the stator 120 side can be increased by connecting the inter-magnet flux barriers 114a-114b with each other rather than by the outer circumferential flux barriers 113a-113b reaching the outer circumferential surface 115 of the rotor core 111. However, as described above, the IPMSM 100 having the optimum shape shown in FIG. 3 has a shape that shows the opposite result.

[0047] Therefore, the present inventors confirmed the results of electromagnetic field analysis (magnetic flux density vectors) in the vicinity of permanent magnets 112a to 112b in IPMSM 100 having the optimum shape shown in FIG. 5A and 5B are diagrams illustrating a second result of the electromagnetic field analysis of the optimally shaped IPMSM 100. Fig. 5A is a diagram showing an example of magnetic flux density vectors in the optimally shaped IPMSM 100, and is the same as Fig. 4A. Fig. 5B is a diagram illustrating an example of the outline of the flow of magnetic flux in the optimally shaped IPMSM 100 near permanent magnets 112a-112b.

[0048] The notation in Fig. 5B is the same as that in Fig. 4B. In Fig. 5B, the arrows indicate the direction of magnetic flux flowing out from the permanent magnets 112a-112b. The arrows extending from the permanent magnets 112a-112b have the same meaning as the arrows shown in the teeth 123c-123d of the stator core 121. In other words, the number of arrows extending from the permanent magnets 112a-112b indicates the relative magnitude relationship of the amount of magnetic flux (magnetic flux density) flowing out from the permanent magnets 112a-112b. Note that the length of the arrows extending from the permanent magnets 112a-112b is unrelated to the magnitude of the magnetic flux.

[0049] 5B, most of the magnetic flux flowing out from the front permanent magnet 112a does not flow toward the inter-magnet bridge portion 117b between the permanent magnets 112a and 112b (the region of the inter-magnet bridge portion 117a shown in FIG. 2 that has not been replaced with a flux barrier), but flows toward the stator 120 (see magnetic flux φ11). Meanwhile, the magnetic flux flowing out from the rear permanent magnet 112b includes magnetic flux that flows toward the stator 120 (see magnetic flux φ12) and also magnetic flux that passes through the inter-magnet bridge portion between the permanent magnets 112a and 112b (see magnetic flux φ13, φ14). However, the magnetic flux flowing out from the rear permanent magnet 112b and passing through the bridge portion between the permanent magnets 112a-112b does not return to the rear permanent magnet 112b, but passes through the front permanent magnet 112a (see magnetic flux φ13) and a region on the inner side of the IPMSM 100 relative to the front permanent magnet 112a toward the stator 120 (see magnetic flux φ14).

[0050] In this way, when inter-magnet flux barriers 114c-114d are provided between permanent magnets 112a-112b, magnetic fluxes φ13 and φ14 that do not become return magnetic flux and contribute to the torque of rotor 110 are present in the magnetic flux that passes through the inter-magnet bridge parts between permanent magnets 112a-112b. Therefore, by providing inter-magnet bridge part 117a, magnetic flux that contributes to the torque of rotor 110 can be generated (see magnetic flux φ13 shown in FIG. 5B). Also, by opening outer periphery side bridge parts 116a-116b by reaching outer periphery surface 115, the return magnetic flux can be reduced and the magnetic flux toward stator 120 can be increased (see magnetic flux φ11 shown in FIG. 5B). In other words, the inventors have gained a third insight that by proactively providing inter-magnet bridge portion 117a and expanding and opening outer periphery-side flux barriers 113a-113b up to outer periphery surface 115 of rotor core 111, it is possible to increase the torque of IPMSM 100 without dividing rotor core 111.

[0051] Here, a case is illustrated in which the cross section (xy cross section) of the rotor 110 in a direction perpendicular to the z-axis direction (the direction in which the axis of rotation extends) is the same at any position in the z-axis direction. However, this is not necessarily required. For example, the rotor core 111 may be so-called skewed. Specifically, the skew is realized by stacking a plurality of soft magnetic blocks in the z-axis direction while rotating them in the same direction by a predetermined angle around the z-axis. In this case, a permanent magnet is installed in each soft magnetic block. Therefore, for example, the number of permanent magnets required is the product of the number of magnet holes in each soft magnetic block and the number of soft magnetic blocks. By applying such a skew, it is possible to suppress vibration of the rotating electric machine.

[0052] Here, soft magnetic bodyThe blocks are manufactured, for example, by stacking multiple soft magnetic plates having the same size and shape so that their contours (inner and outer edges) match. The shapes and sizes of the soft magnetic plates used in each soft magnetic block may be the same or different. However, when multiple soft magnetic blocks are stacked, the outer edges of each soft magnetic block should match. The predetermined angle may be the same or different for each soft magnetic block. The soft magnetic block may also be constructed without using a plate-shaped soft magnetic material.

[0053] ((Fourth Finding)) Furthermore, the inventors considered that if the residual magnetic flux density of the permanent magnets 112a-112b is low, the amount of magnetic flux generated by the permanent magnets 112a-112b is small (magnetic flux density is low), and therefore the magnetic flux is difficult to return. Therefore, electromagnetic field analysis was performed for the IPMSM 100 having the basic shape shown in FIG. 1 when the residual magnetic flux density of the permanent magnets 112a-112b was set to 0.4 T and 1.0 T. FIGS. 6A and 6B are diagrams showing an example of the result of electromagnetic field analysis of the IPMSM 100 having the basic shape when the residual magnetic flux density of the permanent magnets 112a-112b is 0.4 T. FIGS. 7A and 7B are diagrams showing an example of the result of electromagnetic field analysis of the IPMSM 100 having the basic shape when the residual magnetic flux density of the permanent magnets 112a-112b is 1.0 T. 4A to 7B, the conditions other than the residual magnetic flux density of permanent magnets 112a to 112b and the shape of rotor core 111 are the same.

[0054] 6A and 7A are diagrams showing an example of magnetic flux density vectors in the IPMSM 100 of the basic shape when the residual magnetic flux density of the permanent magnets 112a-112b is 0.4 T and 1.0 T, respectively. FIGS. 6B and 7B are diagrams explaining an example of a schematic flow of magnetic flux in the IPMSM 100 of the basic shape when the residual magnetic flux density of the permanent magnets 112a-112b is 0.4 T and 1.0 T, respectively. As with FIGS. 4B and 5B, for convenience of explanation, FIGS. 6B and 7B show a schematic of the flow of magnetic flux necessary for explanation among the magnetic flux in the IPMSM 100 of the basic shape. Note that the meaning of the arrows in FIGS. 6B and 7B is the same as that of the arrows in FIG. 5B.

[0055] In Fig. 6B, when the residual magnetic flux density of the permanent magnets 112a to 112b is 0.4 T, most of the magnetic flux flowing out from the permanent magnets 112a to 112b is return magnetic flux passing through the outer periphery bridge portions 116a to 116b (see magnetic fluxes φ25 and φ26). This corresponds to the result that (part of) the outer periphery flux barriers 113a to 113b shown in Figs. 1 and 2 reach the outer periphery surface 115 of the rotor core 111 and open in the IPMSM 100 having the optimal shape shown in Fig. 3. Also, in Fig. 6B, most of the magnetic flux passing through the inter-magnet bridge portion 117a is not return magnetic flux, similar to the magnetic fluxes φ13 to φ14 shown in Fig. 5B (see magnetic fluxes φ13 to φ14 shown in Fig. 5B and magnetic fluxes φ23 to φ24 shown in Fig. 6B).

[0056] On the other hand, in FIG. 7B, when the residual magnetic flux density of the permanent magnets 112a-112b is 1.0 T, most of the magnetic flux flowing out from the permanent magnets 112a, 112b and passing through the inter-magnet bridge portion 117a becomes return magnetic flux (see magnetic fluxes φ33, φ34). In the result shown in FIG. 7A, the magnetic flux passing through the inter-magnet bridge portion 117a is predominantly return magnetic flux. From this, it can be seen that when the residual magnetic flux density of the permanent magnets 112a-112b is high, the magnetic fluxes φ13-φ14 and φ23-φ24 that do not become return magnetic fluxes shown in FIG. 5B and FIG. 6B become less. Note that in FIG. 7B as well, as in FIG. 6B, there exists return magnetic flux flowing out from the permanent magnets 112a-112b and passing through the outer periphery bridge portions 116a-116b (see magnetic fluxes φ35, φ36). Also in FIG. 7B, similarly to FIG. 6B, there are magnetic fluxes directed from the permanent magnets 112a to 112b toward the stator 120 (see magnetic fluxes φ31 and φ32).

[0057] As described above, the inventors have obtained a fourth finding that when the permanent magnets 112a-112b with low residual magnetic flux density are used, the magnetic flux that does not become a return magnetic flux and contributes to the torque of the rotor 110 is included in a large amount in the magnetic flux passing through the inter-magnet bridge portion 117a. From this, it is considered that, if the conditions other than the residual magnetic flux density of the permanent magnets 112a-112b are the same, the torque of the rotor 110 is improved by providing the inter-magnet bridge portion 117a when the permanent magnets 112a-112b with low residual magnetic flux density are used, compared to when the permanent magnets 112a-112b with high residual magnetic flux density are used. Therefore, by installing the permanent magnets 112a-112b with low residual magnetic flux density in the rotor core 111, the torque of the rotor 110 can be improved. Therefore, for example, it is possible to improve the torque of the rotor 110 without using a permanent magnet containing rare earth. For example, it is possible to improve the torque of the rotor 110 even if a ferrite magnet or the like is used as a permanent magnet that does not contain rare earth. The embodiment of the present invention described below has been made based on the above circumstances.

[0058] As described above, in this section, the rotor 110 rotates in the direction of the arrow line next to the "rotation direction" in FIG. 1 (counterclockwise direction on the paper). However, the explanation in this section does not change depending on the direction in which the rotor 110 rotates. When the rotor 110 rotates in the opposite direction to the direction of the arrow line shown in FIG. 1, the permanent magnets 112 on the front side and the rear side in the explanation in this section become permanent magnets 112b and 112a, respectively. Also, the direction of the magnetic flux and the magnitude relationship of the magnetic flux amount (magnetic flux density) in the teeth 123a to 123d of the stator core 121 are replaced with those shown in FIGS. 4A to 7B. That is, in FIGS. 4B, 5B, 6B, and 7B, the arrow lines pointing outward and the arrow lines pointing inward shown in the teeth 123a to 123d of the stator core 121 point inward and outward, respectively. Also, in FIG. 4B, FIG. 5B, FIG. 6B, and FIG. 7B, two and one arrowed lines become one and two arrowed lines, respectively.

[0059] (Embodiment) An embodiment of the present invention will be described below. In this embodiment, a rotating electric machine is an inner rotor type IPMSM. Fig. 8 is a diagram showing an example of the configuration of an IPMSM 800. Fig. 8 shows the rotation axis of the IPMSM 800 (rotor 810). To 0 8 is a cross-sectional view of the IPMSM800 taken perpendicularly to the axis of rotation of the IPMSM800. As in FIG. 1, the range indicated by the double-headed arrow labeled "1 pole" in FIG. 8 is the portion that constitutes one pole of the IPMSM800. In this embodiment, the case where the IPMSM800 has eight poles is illustrated. However, the number of poles of the IPMSM800 is not limited to eight. As described above, when the IPMSM800 has n poles, the IPMSM800 generally has an n-fold rotational symmetry relationship with the rotation axis 0 of the IPMSM800 as the axis of rotational symmetry. n is an integer equal to or greater than 2, and in the example shown in FIG. 8, n is 8 (n=8).

[0060] In FIG. 8, the IPMSM 800 includes a rotor 810 and a stator 120. The stator 120 is the same as the stator 120 shown in FIG. 1. Therefore, the same reference numerals as those in FIG. 1 are used, and detailed description of the stator 120 is omitted. The IPMSM 800 includes a stator 120 (a stator coil and a stator core 121, not shown) that is determined, for example, as follows. The stator core 121 includes, for example, a yoke portion having a constant width and 24 teeth portions. The width of the yoke portion and the length of the teeth portions are the lengths in the radial direction of the IPMSM 800. The shape of the yoke portion is, for example, annular. The 24 teeth portions are disposed, for example, at equal intervals on the inner circumferential surface of the yoke portion. The width of the yoke portion is, for example, half the difference between the inner diameter and the outer diameter of the stator 120. The length of the teeth portions is, for example, 0.4 times the difference between the inner diameter and the outer diameter of the stator 120. A protrusion is formed on the tip of the tooth portion (the end on the rotation axis 0 side). The protrusion is formed so as to protrude on both sides in the circumferential direction. The circumferential length and width of the protrusion is, for example, 0.3 times the length of the tooth portion. However, the above-mentioned findings do not change depending on the configuration of stator 120, so long as the configuration of stator 120 is a configuration that is generally adopted as a stator for an IPMSM.

[0061] In this embodiment, the case where the excitation current flowing through a stator coil (not shown) included in the stator 120 is a three-phase AC current is illustrated. Therefore, a rotating magnetic field having a period corresponding to the frequency of the three-phase AC current is generated in the stator core 121 (teeth 123). As described above, in FIG. 8 as well as in FIG. 1, only a portion constituting one pole of the rotor 810 is labeled, and the portions constituting the other seven poles of the rotor 810 are omitted.

[0062] The rotor 810 rotates about the rotation axis 0 of the IPMSM 800. The rotor 810 rotates in only one of the counterclockwise direction and the clockwise direction when viewed from the plane of FIG. 8. In this embodiment, the rotor 810 rotates in the counterclockwise direction when viewed from the plane of FIG. 8 (see the arrow next to "rotation direction" in FIG. 8). FIG. 9 is a diagram showing an example of the configuration of the rotor 810 (rotor cross section). In the following description, the rotation direction of the rotor 810 will be abbreviated to the rotation direction as necessary. As described above, in FIG. 9 as well as in FIG. 8, reference numerals are attached to only the portion constituting one pole of the rotor 810, and reference numerals are omitted for the portions constituting the other seven poles of the rotor 810.

[0063] 8 and 9, in this embodiment, the rotor 810 includes a rotor core 811 and a plurality of permanent magnets 812a to 812b per pole. Specifically, in this embodiment, the rotor 810 includes a rotor core 811 and two permanent magnets 812a to 812b per pole. The rotor core 811 is made of a soft magnetic material. The rotor core 811 is made of, for example, a plurality of electromagnetic steel sheets laminated along the rotation axis 0 of the rotor 810. However, the rotor core 811 does not necessarily have to be made of a plurality of laminated electromagnetic steel sheets. The rotor core 811 may be, for example, a dust core, an amorphous core, or a nanocrystalline core. In addition, when the rotor core 811 is a dust core, an amorphous core, or a nanocrystalline core, the soft magnetic material constituting the rotor core 811 is made of insulating-coated soft magnetic particles, an amorphous alloy, or a nanocrystalline alloy, respectively.

[0064] FIG. 10 is a diagram showing an example of the configuration of rotor core 811. As in FIGS. 8 and 9, FIG. 10 is a cross-sectional view of rotor core 811 taken perpendicular to rotation axis 0 of rotor core 811. In the following description, the cross-section of rotor core 811 taken perpendicular to rotation axis 0 of rotor core 811 will be referred to as a rotor core cross-section as necessary. Note that rotation axis 0 of rotor core 811 coincides with rotation axis 0 of IPMSM 800 and rotation axis 0 of rotor 810. As described above, in FIG. 10, as in FIGS. 8 and 9, reference numerals are attached only to a portion constituting one pole of rotor core 811, and reference numerals are omitted for portions constituting the other seven poles of rotor core 811.

[0065] As shown in FIG. 10, in this embodiment, a case where a plurality of magnet holes 817a to 817b are formed in the rotor core 811 per pole is illustrated. Specifically, in this embodiment, a case where two magnet holes 817a to 817b are formed in the rotor core 811 per pole is illustrated. In addition, in this embodiment, a case where the plurality of magnet holes 817a to 817b are through holes penetrating in the z-axis direction is illustrated. In FIGS. 8 to 10, the plurality of permanent magnets 812a, 812b are respectively inserted into the magnet holes 817a, 817b formed in the rotor core 811, and are installed (embedded) in the rotor core 811. Thus, in this embodiment, the rotor core 811 has a plurality of magnet holes 817a to 817b per pole as magnet holes in which the permanent magnets 812a to 812b are installed. Therefore, in the example illustrated in FIG. 10, the magnet hole 817a is the magnet hole on the front side in the rotation direction among the plurality of magnet holes installed in the same pole. In the example shown in FIG. 10, magnet hole 817b is a magnet hole on the rear side in the rotation direction of rotor 810 (rotor core 811). Theory In the following description, magnet hole 817a on the front side in the rotation direction of rotor 810 (rotor core 811) will be referred to as front-side magnet hole 817a as necessary. Also, in the following description, magnet hole 817b on the rear side in the rotation direction of rotor 810 (rotor core 811) will be referred to as rear-side magnet hole 817b as necessary.

[0066] Furthermore, rotor core 811 is provided with holes 816 in which permanent magnets 812a-812b are not installed. Hole 816 is a through hole penetrating in the z-axis direction, and a shaft (not shown) or the like is installed therein. Note that holes other than hole 816 and magnet holes 817a-817b may be formed in rotor core 811. Permanent magnets 812a-812b may or may not be installed in these holes.

[0067] In this embodiment, FIG. 9 illustrates an example in which magnetic flux flows in and out of magnetic pole faces 901a to 901d of permanent magnets 812a to 812b. The direction perpendicular to the magnetic pole faces 901a to 901d is the magnetization direction Dm of the permanent magnets 812a to 812b. As shown in FIG. 9, the magnetization direction Dm of the permanent magnets 812a to 812b is the direction of a double-headed arrow that crosses the permanent magnets 812a to 812b. In FIG. 8 to FIG. 10, the magnet holes 817a to 817b in which the permanent magnets 812a to 812b are installed are manufactured such that the magnetic pole faces 901a to 901d of the permanent magnets 812a to 812b installed in the magnet holes 817a to 817b are inclined with respect to the outer circumferential surface 818 of the rotor core 811. 8 to 10, this embodiment illustrates a case in which magnet holes 817a to 817b are fabricated such that the circumferential intervals between permanent magnets 812a to 812b installed in the magnet holes 817a to 817b become wider the closer they are to the outer circumferential surface 818 of rotor core 811. In this manner, this embodiment illustrates a case in which permanent magnets 812a to 812b are arranged in a so-called V-shape.

[0068] As explained in the section ((Fourth Finding)) of the section (Background), from the viewpoint of reducing the return flux due to the permanent magnets 812a-812b, it is preferable that the residual magnetic flux density of the permanent magnets 812a-812b is low within a range in which the permanent magnets can function as permanent magnets in the IPMSM 800. Note that, functioning as a permanent magnet in the IPMSM 800 means that at least a part of the magnetic flux generated by the permanent magnets reaches the stator 120 and becomes magnetic flux that contributes to the torque of the rotor. When the residual magnetic flux density of the permanent magnets 812a-812b at room temperature exceeds 0.4 T, the amount of magnetic flux generated by the permanent magnets 812a-812b increases, and the return flux included in the magnetic flux passing through the inter-magnet bridge portion 821a increases. As a result, the effect of increasing the torque of the rotor 810 due to the magnetic flux that does not become the return flux (see magnetic fluxes φ13 and φ14 shown in FIG. 5B) is reduced. Furthermore, when the residual magnetic flux density of the permanent magnets 812a-812b at room temperature exceeds 0.8 T, the torque increasing effect of the rotor 810 is significantly reduced. When the residual magnetic flux density of the permanent magnets 812a-812b at room temperature exceeds 0.4 T, it may be necessary to use the permanent magnets 812a-812b that contain rare earth. When the residual magnetic flux density of the permanent magnets 812a-812b at room temperature exceeds 0.8 T, it may be necessary to use the permanent magnets 812a-812b that contain a large amount of rare earth.

[0069] From the above viewpoints, the residual magnetic flux density of the permanent magnets 812a to 812b at room temperature is preferably 0.8 T or less, and more preferably 0.4 T or less. Furthermore, the permanent magnets 812a to 812b preferably contain less rare earth, and more preferably the permanent magnets 812a to 812b do not contain rare earth. However, as long as the permanent magnets 812a to 812b can function as permanent magnets in the IPMSM, the residual magnetic flux density of the permanent magnets 812a to 812b at room temperature does not have to be in the above-mentioned range.

[0070] In Fig. 9, flux barriers 813a-813b and 814a-814b are spaces in magnet holes 817a-817b in which permanent magnets 812a-812b shown in Fig. 10 are placed, where no permanent magnets 812a-812b exist. No tangible objects exist in the flux barriers 813a-813b and 814a-814b. That is, the flux barriers 813a-813b and 814a-814b are voids (areas of air). The flux barriers 813a-813b and 814a-814b are areas where magnetic flux does not pass, or areas where magnetic flux passes more difficultly than the areas around the flux barriers 813a-813b and 814a-814b. As described above, in this embodiment, a case where no tangible object exists in the flux barriers 813a-813b, 814a-814b is illustrated. However, this is not necessarily required. For example, the flux barriers 813a-813b, 814a-814b may be configured by placing a non-magnetic object in the space where the permanent magnets 812a-812b do not exist among the magnet holes 817a-817b in which the permanent magnets 812a-812b shown in FIG. 10 are placed.

[0071] In FIG. 9, the flux barriers 813a-813b located on the outer periphery side in the left-right direction Ds from the permanent magnets 812a-812b are outer periphery side flux barriers. The outer periphery side flux barriers 813a-813b reach and open at an outer periphery surface 818 of the rotor 810 (rotor core 811) in the rotor cross section. On the other hand, the flux barriers 814a-814b located on the inner periphery side in the left-right direction Ds from the permanent magnets 812a-812b are inter-magnet flux barriers. The inter-magnet flux barriers 814a-814b are not open except at their ends in the z-axis direction. The outer periphery side refers to the outer periphery surface 818 side of the rotor core 811, and the inner periphery side refers to the inner periphery surface 819 side of the rotor core 811.

[0072] As described above, the permanent magnet 812a is the front side permanent magnet 812a located forward of the permanent magnet 812b, and the permanent magnet 812b is the rear side permanent magnet 812b. The outer periphery side flux barrier 813a located on the outer periphery side of the front side permanent magnet 812a is located forward of the front side permanent magnet 812a in the rotation direction. On the other hand, the outer periphery side flux barrier 813b located on the outer periphery side of the rear side permanent magnet 812b is located rear of the rear side permanent magnet 812b in the rotation direction.

[0073] As shown in FIG. 10, a recess 815a is formed on an outer peripheral surface 818 of the rotor core 811. The recess 815a is formed at a position facing, with a gap, the teeth 123a, 123b, which are different from the teeth 123b, 123d, which have the lowest magnetic flux density, among the teeth 123 of the stator core 121, which are installed at a position facing, with a gap, the outer peripheral surface 818 of the rotor core 811. As described in the section (Background), the rotation period of the rotor core 811 is the same as the rotation period of the rotating magnetic field generated in the stator core 121 (teeth 123). Therefore, even if the rotor core 811 rotates, the magnetic flux density of the teeth 123 facing the recess 815a is the same. In this embodiment, a case where one recess 815a is formed per pole is illustrated. However, the number of recesses 815 per pole may be two or more. The magnetic flux density of teeth 123a, 123c of stator core 121 that are disposed at a position facing recessed portion 815a with a gap therebetween is preferably high, and more preferably has the highest magnetic flux density, because this allows the torque of rotor 810 to be increased.

[0074] FIG. 11A is an enlarged view of a portion of rotor core 811 shown in FIG. 10 (a view showing a cross section of the rotor core). FIGS. 11B and 11C are modified examples of FIG. 11A. An example of the configuration of rotor core 811 of this embodiment will be described in detail with reference to FIG. 10 and FIGS. 11A to 11C. Note that in FIGS. 11A to 11C, hatching indicating a cross section is omitted to avoid making the positions indicated by the respective reference symbols unclear. In Fig. 10, the area of ​​the soft magnetic material (area other than holes 816 and magnet holes 817a-817b) among the area occupied by rotor core 811 is soft magnetic material portion 820. As shown in Fig. 10 and Fig. 11A, in a cross section of the rotor core, magnet holes 817a-817b in which permanent magnets 812a-812b are installed have first ends 1111a-1111b, second ends 1112a-1112b, third ends 1113a-1113b, and fourth ends 1114a-1114b. An example of first ends 1111a-1111b, second ends 1112a-1112b, third ends 1113a-1113b, and fourth ends 1114a-1114b will be described below.

[0075] First, the first ends 1111a to 1111b will be described. The first ends 1111a to 1111b are ends located on the outermost side of the spaces that become the outer periphery flux barriers 813a to 813b of the magnet holes 817a to 817b. The first ends 1111a to 1111b are open ends that open at the position of the outer periphery surface 818 of the rotor core 811 in the rotor core cross section. For this reason, in the following description, the first ends 1111 may also be referred to as the open ends 1011. In the following description, a bent or curved portion in the rotor core cross section will be referred to as a corner portion as necessary. However, a region of the outer periphery surface 818 of the rotor core 811 that is different from the open ends (a region of a circular arc whose distance from the rotation axis 0 is the length of the radius of the rotor 810) is not considered to be a corner portion.

[0076] In the rotor core cross section, when the bent portion of magnet holes 817a-817b is a corner portion, the position of the corner portion is the bent position. In the rotor core cross section, when the curved portion of magnet holes 817a-817b is a corner portion, the position of the corner portion is the position of the representative point of the curved portion (portion having curvature). Details of these will be explained with reference to Figs. 11A-11C described later. In the example shown in Fig. 11A, first ends 1111a-1111b are a region along the circumferential direction from one to the other of two corners 1131a-1131b, 1131c-1131d located at the outer circumferential surface 818 (the outermost side) of rotor core 811 among the 12 corners of one magnet hole 817a-817b. The circumferential direction is a direction around the outer circumferential surface 818 of the rotor 810 (rotor core 811) (a direction parallel and anti-parallel to the rotation direction of the rotor 810 (rotor core 811)).

[0077] If the circumferential length L1 of the first ends 1111a to 1111b is too short, the magnetic resistance at the first ends 1111a to 1111b becomes too small. As a result, the magnetic flux that overcomes the magnet holes 817a to 817b in the circumferential direction increases, and there is a risk of the return magnetic flux increasing. On the other hand, if the circumferential length L1 of the first ends 1111a to 1111b is too long, the outer parts 822a to 822h become small, and there is a risk of the magnetic flux that contributes to the torque of the rotor 810 decreasing. The circumferential length L1 of the first ends 1111a to 1111b is appropriately determined from such a viewpoint. The circumferential length L1 of the first ends 1111a to 1111b may be determined, for example, within a range of 0.1 to 1.0 times the length L2 of the magnetization direction Dm of the permanent magnets 812a to 812b. In this embodiment, the case where the length of the magnetization direction Dm of the permanent magnets 812a-812b is constant is illustrated. However, the length of the magnetization direction Dm of the permanent magnets 812a-812b does not have to be constant. When the length of the magnetization direction Dm of the permanent magnets 812a-812b is not constant, the circumferential length L1 of the first end portions 1111a-1111b may be determined by taking a representative value (for example, an average value) of the length L2 of the magnetization direction Dm of the permanent magnets 812a-812b as the length of the magnetization direction Dm of the permanent magnets 812a-812b.

[0078] Similarly to the circumferential length L1 of first ends 1111a-1111b, the length of other regions of magnet holes 817a-817b in the cross section of the rotor core is determined from the viewpoints of suppressing return flux and ensuring magnetic paths and strength. For example, the minimum value of the length between two opposing ends of magnet holes 817a-817b in the cross section of the rotor core may be determined within a range of 0.1 to 1.0 times the length in the magnetization direction Dm of permanent magnets 812a-812b.

[0079] As explained in the section ((First Finding)) of the section (Background), the torque of the rotor 810 is increased by shifting the first ends 1111a-1111b, which are the open ends of the outer periphery-side flux barriers 813a-813b, toward the rear side in the rotation direction of the rotor core 811 (the opposite side to the rotation direction). To achieve this, in this embodiment, as shown in Fig. 11A, in a cross section of the rotor core, the positions of the open end front side corner portions 1131a, 1131c of the first ends 1111a, 1111b, which are the open ends, are positioned rearward in the rotation direction of the rotor core 811 from the reference positions 831a, 831b with respect to the magnet holes 817a, 817b having the first ends 1111a, 1111b, which are the open ends. Front open end corner portions 1131a, 1131c of first ends 1111a, 1111b are the front corner portions in the rotation direction of rotor core 811 among the corner portions of first ends 1111a, 1111b in a cross section of the rotor core.

[0080] Here, the reference positions 831a, 831b for magnet holes 817a, 817b having first ends 1111a, 1111b which are open ends are located at the intersection of straight lines 1172, 1174 which pass through the rotation axis 0 and permanent magnet reference ends 841a, 841b which are one of the ends of permanent magnets 812a, 812b installed in the magnet holes 817a, 817b, and the outer surface 818 of the rotor core 811, as shown in Figure 11A, in the rotor core cross section. The permanent magnet reference ends 841a, 841b of magnet holes 817a, 817b having first ends 1111a, 1111b which are open ends are the ends of the one permanent magnet 812a or 812b which is located closest to the respective open ends (first ends 1111a or 1111b) among the ends of the permanent magnets 812a, 812b installed in the magnet holes 817a, 817b. Permanent magnet reference ends 841a, 841b of magnet holes 817a, 817b having first ends 1111a, 1111b that are open ends are the ends of one permanent magnet 812a or 812b that are closest to the open ends, and are located at the furthest circumferential distance from a straight line 1177 that passes through the rotation axis 0 (origin 0) and the circumferential center position of a region (region surrounded by a dashed line in FIG. 3) of one pole (magnetic pole) (of the rotor) that includes the permanent magnet 812a or 812b in the rotor core cross section. Here, the circumferential distance from the straight line 1177 is the distance determined on the side where the open end exists, either the front side or the rear side in the rotation direction of rotor core 811. 11A, permanent magnet reference end 841a of magnet hole 817a having first end 1111a which is an open end is the end of permanent magnet 812a which is located at the farthest position in the circumferential direction from line 1177 on the forward side which is closer to first end 1111a than line 1177. Moreover, permanent magnet reference end 841b of magnet hole 817b having first end 1111b which is an open end is the end of permanent magnet 812b which is located at the farthest position in the circumferential direction from line 1177 on the rear side which is closer to first end 1111b than line 1177.

[0081] In addition, in Fig. 11A, for convenience of notation, multiple rotation axes 0 are shown, but there is actually one rotation axis 0 as shown in Figs. 8 to 10 (the rotation axes 0 shown in Fig. 11A overlap at one position). This is the same as in Figs. 11B and 11C described below. In this embodiment, magnet holes 817a and 817b are located on the front side and the rear side, respectively, of straight line 1177 in the rotation direction of rotor core 811. Therefore, permanent magnet reference ends 841a and 841b are located only on either the front side or the rear side, respectively, of straight line 1177 in the rotation direction of rotor core 811. In contrast to this, for example, assume that magnet holes 817a-817b are arranged to straddle straight line 1177, and that outer periphery-side flux barriers 113a-113b, 114a-114b formed on both sides in the left-right direction Ds of permanent magnets 812a-812b installed in magnet holes 817a-817b both have open ends on outer periphery 818 of rotor core 811. In this case, permanent magnet reference ends 841a, 841b are located on the front and rear sides, respectively, of straight line 1177 in the rotation direction of rotor core 811 in the rotor core cross section.

[0082] 11A to 11C, the position of the center in the circumferential direction of one pole region of the rotor is determined as the position of the midpoint of an imaginary line connecting the permanent magnet reference ends 841a and 841b. A straight line passing through this center position and the rotation axis 0 (origin 0) is defined as a straight line 1177.

[0083] In the following description, the open end front corner portions 1131a, 1131c will be referred to as the front open end front corner portion and the rear open end front corner portion, respectively, as necessary. Also, in the following description, the open end 1111a of the front magnet hole 817a and the open end 1111b of the rear magnet hole 817b will be referred to as the front open end 1111a and the rear open end 1111b, respectively, as necessary.

[0084] The front open end front corner portion 1131a is the front corner portion 1131a in the rotational direction of the rotor core 811, of the two corner portions 1131a to 1131b in the circumferential direction of the rotor core 811 of the front open end portion 1111a, which is the open end of the space 1123a that serves as the outer circumferential flux barrier of the front magnet hole 817a.

[0085] The rear open end front corner portion 1131c is the rear open end 111 which is the open end of the space 1123b which serves as the outer circumferential flux barrier of the rear magnet hole 817b. 1 Of the two corner portions 1131c to 1131d in the circumferential direction of rotor core 811, the corner portion 1131c is located on the front side in the rotation direction of rotor core 811.

[0086] Further, in a cross section of the rotor core, permanent magnet reference ends 841a-841b have a front side permanent magnet end 841a and a rear side permanent magnet end 841b. Front side permanent magnet end 841a is the end located at the frontmost position in the rotation direction among the ends of permanent magnets 812a-812b installed in front side magnet hole 817a. Rear side permanent magnet end 841b is the end located at the rearmost position in the rotation direction among the ends of permanent magnet 812b installed in rear side magnet hole 817b.

[0087] In addition, in the rotor core cross section, the reference positions 831a to 831b include a front reference position 831a. a is , the position of the intersection of a straight line 1172 passing through the front permanent magnet end 841 a and the rotation axis 0 and the outer circumferential surface 818 of the rotor core 811 .

[0088] Further, in the cross section of the rotor core, the reference positions 831a-831b include a rear reference position 831b. The rear reference position 831b is the position of the intersection of a straight line 1174 passing through a rear permanent magnet end 841b and the rotation axis 0 and an outer circumferential surface 818 of the rotor core 811.

[0089] Here, from the viewpoint of reliably improving the torque of the rotor 810, it is preferable to determine the positions of the open end front corner portions (front open end front corner portion 1131a and rear open end front corner portion 1131c) as follows. The number of slots of the stator core 121 that is disposed at a position facing the outer circumferential surface 818 of the rotor core 811 with a gap therebetween is defined as N. slot In addition, the reference position movement angle θa (rad), which is the angle from the reference positions 831a to 831b around the rotation axis 0, is expressed as 2π / N slot In the example shown in FIG. 8, the number of slots in the stator core 121 is N slot Since there are 24, the reference position movement angle θa is 2π / 24 (rad) = 15 (°).

[0090] In the rotor core cross section, the angle θf between the lines 1171 and 1172 is preferably θa / 24 or more and 15θa / 24 or less, and more preferably within the range of θa / 3±θa / 24. The line 1171 is a line that passes through the front corner portion 1131a of the front open end and the rotation axis 0 in the rotor core cross section. before The front open end front corner 1131a is a corner located forward in the rotation direction from the circumferential center of the same pole among the open end front corners 1131a and 1131c in the rotor core cross section. A straight line 1172 is a straight line passing through the rotation axis 0 and a reference position 831a for a magnet hole 817a having an open end 1111a with the front open end front corner 1131a as one of its corners in the rotor core cross section. In the following description, this angle θf will be referred to as the outer periphery side flux barrier movement angle θf on the front side as necessary.

[0091] In addition, in the rotor core cross section, the angle θb between the straight lines 1173 and 1174 is preferably θa / 24 or more and θa / 8 or less, and more preferably within the range of θa / 12±θa / 24. The straight line 1173 is a straight line passing through the rear open end front corner 1131c and the rotation axis 0 in the rotor core cross section. The rear open end front corner 1131c is a corner of the open end front corners 1131a and 1131c that is located rearward in the rotation direction from the circumferential center of the same pole. The straight line 1174 is a straight line passing through the reference position 831b for the magnet hole 817b having the open end 1111b with the rear open end front corner 1131c as one of its corners, and the rotation axis 0 in the rotor core cross section. In the following description, this angle θb will be referred to as the movement angle θb of the outer circumferential flux barrier on the rear side, as necessary.

[0092] As explained in the section ((Second Findings)) of the section (Background), the torque of the rotor 810 is increased by providing the recessed portion 815a at a position facing the teeth 123a, 123b having a higher magnetic flux density than the minimum magnetic flux density in the region of the outer circumferential surface 818 of the rotor core 811. In order to further enhance the effect of increasing the torque of the rotor 810, it is preferable that the entire region of the recessed portion 815a faces the teeth 123a, 123b having the magnetic flux density. However, a part of the region of the recessed portion 815a may face the teeth 123a, 123b having the magnetic flux density. In addition, from the viewpoint of reliably improving the torque of the rotor 810, it is preferable to determine the recessed portion 815a as follows.

[0093] As shown in FIG. 11A, in the rotor core cross section, the reference position movement angle θa (rad), which is the angle from the rear reference position 831b around the rotation axis 0, is expressed as 2π / N slotThe rear side reference position 831b is the position of the intersection of a straight line 1174 passing through the rear side permanent magnet end 841b and the rotation axis 0 and the outer circumferential surface 818 of the rotor core 811 in the rotor core cross section. The rear side permanent magnet end 841b is the end located furthest rearward in the circumferential direction among the ends of the permanent magnets 812a to 812b that are installed with the same pole. As described above, in the example shown in FIG. 8, the number of slots in the stator core 121 is N. slot The number of the reference position movement angles θa is 2π / 24 (rad) = 15 (°).

[0094] First, in the rotor core cross section, it is preferable that the angle formed by the straight lines 1175 and 1173 is θa. The straight line 1175 is a straight line passing through the recess rear corner 1161a and the rotation axis 0 in the rotor core cross section. The recess rear corner 1161a is a corner located on the rear side in the rotation direction among the two corners 1161a to 1161b at the open end 1151a of the recess 815a in the rotor core cross section. The straight line 1173 is a straight line passing through the rear open end front corner 1131c and the rotation axis 0 in the rotor core cross section. The rear open end front corner 1131c is located on the rear side in the rotation direction of the recess 815a in the same pole as the pole on which the recess 815a is installed.

[0095] In addition, in the rotor core cross section, the angle θc between the straight lines 1176 and 1175 is preferably θa / 8 or more and 25θa / 24θa or less, and more preferably within the range of 3θa / 4±θa / 12. The straight line 1176 is a straight line passing through the recessed front corner 1161b and the rotation axis 0 in the rotor core cross section. The recessed front corner 1161b is the corner on the front side in the rotation direction of the two corners 1161a to 1161b at the open end 1151a of the recess 815a in the rotor core cross section. The straight line 1175 is a straight line passing through the recessed rear corner 1161a and the rotation axis 0 in the rotor core cross section. In the following description, this angle θc is referred to as the recess opening angle θc as necessary.

[0096] The maximum depth Cd of the recess 815a is 0.01 to 0.1 times the diameter of the rotor core 811. Double It is preferable that the maximum depth Cd of the recess 815a is within the following range, and more preferably within the range of 0.04 to 0.07 times the diameter of the rotor core 811. In the following description, the maximum depth Cd of the recess 815a will be referred to as the maximum recess depth Cd as necessary.

[0097] Further, the shape of the recessed portion 815a is not limited. FIG. 11A illustrates an example in which the planar shape of the recessed portion 815a (shape of the rotor core cross section) is a quadrangle that has a line symmetrical relationship with respect to a line passing through the position of the center of gravity of the recessed portion 815a and the rotation axis 0 of the rotor core 811 as the axis of symmetry. However, the planar shape of the recessed portion 815a may be a shape that does not have symmetry. Furthermore, the planar shape of the recessed portion 815a may be a triangle or a polygon having pentagons or more sides. Furthermore, the corners of the recessed portion 815a may have a curvature.

[0098] Next, the second ends 1112a-1112b will be described. The second ends 1112a-1112b are ends located on the inner periphery side of the magnet holes 817a-817b in the left-right direction Ds. The second ends 1112a-1112b coincide with the ends of the inter-magnet flux barriers 814a-814b and are closed. In other words, the magnet holes 817a-817b have a shape such that, when the permanent magnets 812a-812b are installed, a space that serves as a flux barrier extending along the rotation axis O is formed between the permanent magnets 812a-812b and the second ends 1112a-1112b.

[0099] 11A, second ends 1112a-1112b are regions along the contours of magnet holes 817a-817b from one to the other of two corners 1132a-1132b, 1132c-1132d of magnet holes 817a-817b in which permanent magnets 812a-812b are installed in the cross section of the rotor core. Corner portions 1132a-1132b, 1132c-1132d constituting second ends 1112a-1112b are determined by the designer of IPMSM 800 so that magnet holes 817a-817b face each other with inter-magnet bridge portion 821 between them. In the example shown in FIG. 11A, the second ends 1112a-1112b include the positions of both ends of a straight line connecting, over the shortest distance, the second ends 1112a-1112b of two magnet holes 817a-817b that face each other across the inter-magnet bridge portion 821 in the cross section of the rotor core.

[0100] In the example shown in Fig. 11A, the area of ​​the soft magnetic material where the most stress is concentrated when the rotor 810 (rotor core 811) is rotating is included between the second ends 1112a-1112b. In the example shown in Fig. 11A, the straight line that connects the second ends 1112a-1112b at the shortest distance is the straight line 1141a that connects the corners 1132a and 1132c. In the example shown in Fig. 11A, the inter-magnet bridge portion 821a is defined as the area of ​​the soft magnetic material surrounded by, for example, the straight line 1141a that connects the two corners 1132a and 1132c and the straight line 1141b that connects the two corners 1132b and 1132d.

[0101] 11A illustrates a case where the entire area between two magnet holes 817a-817b is a soft magnetic material area. Therefore, the straight line 1141a connecting the second ends 1112a-1112b of the two magnet holes 817a-817b at the shortest distance is the same as the straight line drawn between the second ends 1112a-1112b so that the length of overlap with the soft magnetic material area is the shortest. On the other hand, when a flux barrier is formed in the area between two magnet holes 817a-817b, this is not necessarily the case. This is because the straight line connecting the second ends 1112a-1112b of the two magnet holes 817a-817b at the shortest distance may overlap with the flux barrier. As described above, the soft magnetic material area where the most stress is concentrated when the rotor 810 (rotor core 811) is rotating is included between the second ends 1112a-1112b. Furthermore, the second ends 1112a-1112b include the positions of both ends of a straight line drawn between the second ends 1112a-1112b so as to minimize the length of overlap with the soft magnetic material region. In this way, regardless of whether there is a flux barrier in the region between the second ends 1112a-1112b, the region of the soft magnetic material where the most stress is concentrated when the rotor 810 (rotor core 811) is rotating can be included between the second ends 1112a-1112b.

[0102] FIG. 11B is a diagram showing a first modified example of the configuration of rotor core 811 (cross section of rotor core). 11B, for example, the area of ​​the soft magnetic material surrounded by the straight line 1141c connecting the two corners 1132e and 1132h and the straight line 1141d connecting the two corners 1132g and 1132j is defined as the area of ​​the inter-magnet bridge portion 821i. In this case, the second ends 1112c and 1112d are areas that follow the contours of the magnet holes 817c to 817d from one to the other of the two corners 1132e and 1132g, 1132h and 1132j of the magnet holes 817c and 817d in which the permanent magnets 812a and 812b are installed.

[0103] 11B, instead of the above, for example, the area of ​​the soft magnetic material surrounded by the straight line 1141c connecting the two corners 1132e, 1132h and the straight line 1141e connecting the two corners 1132f, 1132i may be defined as the area to be the inter-magnet bridge portion. In this case, the second ends 1112c, 1112d become the area along the outline of the magnet hole 817 from one to the other of the two corners 1132e, 1132f, 1132h, and 1132i of the magnet holes 817c, 817d in which the permanent magnets 812a to 812b are installed. In addition, the second end 1112 may be a region that follows the contour of the magnet holes 817c, 817d from one to the other of the two corner portions 1132f and 1132g, 1132i and 1132j of the magnet holes 817c, 817d in which the permanent magnets 812a, 812b are installed.

[0104] 11B, the positions of both ends of a straight line drawn to minimize the length of overlap with the soft magnetic material constituting the soft magnetic body part 820 are the positions of the corner parts 1132f, 1132i. Therefore, the second ends 1112c to 1112d include the positions of the corner parts 1132f, 1132i.

[0105] 11A and 11B, a case is illustrated in which two corner portions 1132 that define second end portion 1112 have no curvature in rotor core cross section. Fig. 11C is a diagram showing a second modified example of the configuration (rotor core cross section) of rotor core 811. Fig. 11C illustrates a case in which corner portions 1132a-1132d of second end portions 1112a-1112b in Fig. 11A are changed to corner portions 1132k-1132n having curvature.

[0106] When the corners 1132k to 1132n have a curvature, the positions of the corners 1132k to 1132n are assumed to be the positions of the representative points of the areas having the curvature. The representative points of the corners are selected, for example, so that the size of the bridge between the magnets is the largest. In this case, in the example shown in FIG. 11C, the positions of the black circles (●) indicating the corners 1132k to 1132n are the positions of the representative points of the corners 1132k to 1132n. The positions of the representative points of the corners 1132k to 1132n thus determined are treated as the positions of the corners 1132k to 1132n. It should be noted that the representative points of the corners do not necessarily need to be selected so that the size of the bridge between the magnets is the largest. For example, the center position of the area forming the corners may be selected as the representative point of the corners. 11C, second ends 1112e, 1112f are regions that follow the contours of magnet holes 817e, 817f from one to the other of two corners 1132k-1132l, 1132m-1132n of magnet holes 817e, 817f in which permanent magnets 812a, 812b are installed. Alternatively, a representative point of the corners may be selected so that the size of the bridge between the magnets is smallest.

[0107] 11C, the positions of both ends of the straight line 1141h correspond to the positions of both ends of the straight line drawn so as to minimize the length of overlap with the soft magnetic material constituting the soft magnetic body part 820. Therefore, the second ends 1112e to 1112f include the positions of both ends of the straight line 1141h.

[0108] Furthermore, when a corner portion of first end portion 1111 has a curvature, the representative point of the region having the curvature may be set to the position of the corner portion of first end portion 1111. The representative point of the corner portion of first end portion 1111 is set to a position on outer circumferential surface 818 of rotor core 811 so that first end portion 1111 is at its widest. However, this is not necessarily required. For example, the center position of the region having the curvature may be set to the representative point of the corner portion of first end portion 1111.

[0109] Returning to the explanation of Fig. 11A, the third ends 1113a to 1113b will be explained. The third ends 1113a to 1113b are ends located on the outer periphery side in the magnetization direction Dm of the permanent magnets 812a to 812b. The outer periphery side in the magnetization direction Dm of the permanent magnets 812a to 812b is the side closer to the outer periphery surface 818 of the rotor core 811. 11A, the third ends 1113a, 1113b are regions along the contours of the magnet holes 817a, 817b from the inner corners 1131b, 1131c of the two corners 1131a-1131b, 1131c-1131d that define the first ends 1111a, 1111b to the outer corners 1132a, 1132c of the two corners 1132a-1132b, 1132c-1132d that define the second ends 1112a, 1112b that are located on the outer periphery in the magnetization direction Dm of the permanent magnets 812a, 812b. The inner side is the side closer to the center position in the circumferential direction of the region of one pole of the rotor. In the example shown in Fig. 11B, third ends 1113c, 1113d are, for example, the regions along the contours of magnet holes 817c, 817d from corners 1131b, 1131c that define first end 1111 to corners 1132e, 1132h that define second end 1112. In the example shown in Fig. 11C, third ends 1113e, 1113f are the regions along the contours of magnet holes 817e, 817f from corners 1131b, 1131c that define first end 1111 to corners 1132k, 1132m that define second end 1112.

[0110] Returning to the description of FIG. 11A, the fourth ends 1114a to 1114b will be described. The fourth ends 1114a to 1114b are ends located on the inner periphery side in the magnetization direction Dm of the permanent magnets 812a and 812b. In the example shown in FIG. 11A, the fourth ends 1114a and 1114b are located between the outer corners 1131a and 1131d of the two corners 1131a to 1131b and 1131c to 1131d that define the first ends 1111a and 1111b and the second ends 1111a and 1111b. Part 1The outer side is the side closer to the end in the circumferential direction of one pole of the rotor. In the example shown in FIG. 11B, the fourth end 1114c, 1114d is, for example, the first end 1114c, 1114d. 1 11C, fourth ends 1114e, 1114f are the areas along the contours of magnet holes 817e, 817f from corners 1131a, 1131d that define first end 1111 to corners 1132l, 1132n that define second end 1112.

[0111] 11A to 11C, there are two magnet holes 817a to 817b, 817 in which permanent magnets 812a to 812b are installed. c ~817 d , 817 e ~817 f The magnet holder 112 has spaces 1121a to 1121b in which the permanent magnets 812a to 812b are placed. The magnet holder 112 has two magnet holes 817a to 817b, 817 c ~817 d , 817 e ~817 f The magnet 812 has spaces 1122a to 1122b, 1122c to 1122d, and 1122e to 1122f that serve as inter-magnet flux barriers between the spaces 1121a to 1121b in which the permanent magnets are installed and the second end 1112a to 1112b, 1112c to 1112d, and 1112e to 1112f. In addition, the magnet 812 has two magnet holes 817a to 817b, 817 c ~817 d , 817 e ~817 f In FIG. 1, a space 1121a to 1121b in which the permanent magnets are disposed and a space 1111a to 1111b are provided between the first end portions 1111a to 1111b. 9The spaces 1123a to 1123b serving as the outer periphery side flux barriers 813a to 813b are b Yes.

[0112] In the following description, there will be referred to spaces 1121a to 1121b in which permanent magnets 812a to 812b are installed, spaces 1122a to 1122b, 1122c to 1122d, and 1122e to 1122f which serve as inter-magnet flux barriers, and spaces 1123a to 1123 which serve as outer circumferential flux barriers. b , and, as necessary, magnet installation spaces 1121a to 112 1 b, flux barrier spaces between magnets 1122a to 1122b, 1122c to 1122d, 1122e to 1122f, flux barrier spaces on the outer periphery 1123a to 1123 b and The magnet installation spaces 1121a to 112 1 b, flux barrier spaces between magnets 1122a to 1122b, 1122c to 1122d, 1122e to 1122f, flux barrier spaces on the outer periphery 1123a to 1123 b We will explain about this.

[0113] In the front magnet hole 817a, the outer periphery flux barrier space 1123a is an example of a space that serves as a front flux barrier. In the rear magnet hole 817b, the outer periphery flux barrier space 1123b is an example of a space that serves as a rear flux barrier. In the front magnet hole 817a, the inter-magnet flux barrier space 1122a is an example of a space that serves as a rear flux barrier. In the rear magnet hole 817b, the inter-magnet flux barrier space 1122b is an example of a space that serves as a front flux barrier. That is, in the front magnet hole 817a and the rear magnet hole 817b, the spaces that serve as the front flux barrier (the outer periphery flux barrier space 1123a, the inter-magnet flux barrier space 1122b) are located further forward in the rotation direction than the spaces that serve as the rear flux barrier (the inter-magnet flux barrier space 1122a, the outer periphery flux barrier space 1123b).

[0114] More specifically, outer periphery flux barrier space 1123a of front side magnet hole 817a is located forward in the direction of rotation than inter-magnet flux barrier space 1122a of front side magnet hole 817a, and is further toward the outer periphery of rotor core 811 than inter-magnet flux barrier space 1122a of front side magnet hole 817a. In addition, outer periphery flux barrier space 1123b of rear side magnet hole 817b is located rearward in the direction of rotation than inter-magnet flux barrier space 1122b of rear side magnet hole 817b, and is further toward the outer periphery of rotor core 811 than inter-magnet flux barrier space 1122b of rear side magnet hole 817b. Further, the outer periphery flux barrier space 1123a of the front magnet hole 817a and the outer periphery flux barrier space 1123b of the rear magnet hole 817b have first ends 1111a-1111b which are open ends. In this manner, it is preferable that both of the outer periphery flux barrier spaces 1123a and 1123b have open ends (first ends 1111a-1111b). However, only one of the outer periphery flux barrier spaces 1123a and 1123b may have an open end (first end 1111).

[0115] In the rotor core cross section shown in FIG. 11A to FIG. 11C, the widthwise length L2 of the magnet installation spaces 1121a to 1121b, which is a direction along the magnetization direction Dm of the permanent magnets 812a to 812b, is equal to the length corresponding to the length of the magnetization direction Dm of the permanent magnets 812a to 812b and is almost constant. The widthwise length L2 of the magnet installation spaces 1121a to 1121b may be the same as the length of the magnetization direction Dm of the permanent magnets 812a to 812b, or may be (slightly) longer than the length of the magnetization direction Dm of the permanent magnets 812a to 812b in order to facilitate installation of the permanent magnets 812a to 812b in the magnet holes 817a to 817b. Note that in this embodiment, a case in which the length of the magnetization direction Dm of the permanent magnets 812a to 812b is constant is illustrated. However, the length of the magnetization direction Dm of the permanent magnets 812a to 812b does not necessarily have to be constant. If the length of the magnetization direction Dm of the permanent magnets 812a to 812b is not constant, the widthwise length of the magnet installation spaces 1121a to 1121b may be set equal to the length corresponding to the length of the magnetization direction Dm of the permanent magnets 812a to 812b. In this case, the widthwise length of the magnet installation spaces 1121a to 1121b is not constant.

[0116] When the permanent magnets 812a to 812b are installed, at least a part of the magnet installation spaces 1121a to 1121b is occupied by the permanent magnets 812a to 812b and is no longer a space. 9 9 and remain as empty spaces even when the permanent magnets 812a to 812b are installed. The outer periphery side flux barrier spaces 1123a to 1123b correspond to the outer periphery side flux barriers 813a to 813b shown in FIG. 9 and remain as empty spaces even when the permanent magnets 812a to 812b are installed. The inter-magnet flux barrier spaces 1122a to 1122f and the outer periphery side flux barrier spaces 1123a to 1123b correspond to the outer periphery side flux barriers 813a to 813b shown in FIG. b When a non-magnetic body is placed in the flux barrier spaces 1122a to 1122f between the magnets and the flux barrier spaces 1123a to 1123f on the outer periphery, b At least a portion of the region is occupied by a non-magnetic material.

[0117] Next, an example of the configuration of the soft magnetic material part 820 will be described with reference to Fig. 10 and Fig. 11A to Fig. 11C. Note that here, a case in which corner parts 1132e and 1132g are two corner parts of the second end part 1112c in Fig. 11B, and corner parts 1132h and 1132j are two corner parts of the second end part 1112d will be illustrated.

[0118] In FIG. 10, soft magnetic material section 820 has inter-magnet bridge sections 821a to 821h, outer sections 822a to 822h, and an inner section 823a.

[0119] The inter-magnet bridge portions 821a to 821h are areas of the outer edge of the bridge where a soft magnetic material is present. In the example shown in Figures 10 and 11A, the bridge outer edge portion is a region surrounded by a straight line connecting the outer peripheral corner portions 1132a, 1132c of the second ends 1112a-1112b of two magnet holes 817a-817b in which permanent magnets 812a-812b with the same pole are installed (see the two-dot chain line connecting the outer peripheral ends of the second ends 1112a-1112b in Figure 10), a straight line connecting the inner peripheral corner portions 1132b, 1132d of the second ends 1112a-1112b of the two magnet holes 817a-817b (see the two-dot chain line connecting the inner peripheral ends of the second ends 1112a-1112b in Figure 10), and the second ends 1112a-1112b of the two magnet holes 817a-817b. In FIG. 10, in this embodiment, the bridge outer edge portion 831a is illustrated as having only a soft magnetic material. The presence of only a soft magnetic material means that no area other than the soft magnetic material, such as a flux barrier, is included. Therefore, in this embodiment, the inter-magnet bridge portion 821a coincides with the bridge outer edge portion 831a. Note that in FIG. 10 and FIG. 11A, the bridge outer edge portion 831a corresponds to the area between the second ends 1112a-1112b of the two magnet holes 817a-817b in which the permanent magnets 812a-812b are installed at the same pole. In addition, the area between the second ends 1112a-1112b of the two magnet holes 817a-817b in which the permanent magnets 812a-812b are installed at the same pole may include an area other than the soft magnetic material, such as a flux barrier. In this case, the inter-magnet bridge portion 821a is the area obtained by excluding the area other than the soft magnetic material from the bridge outer edge portion 831a. Moreover, the number of inter-magnet bridge portions 821a to 821h is equal to the number of poles of the rotor 810 (8 in this embodiment).

[0120] Specifically, in the example shown in FIG. 11A, bridge outer edge portion 831a is formed by straight line 1141a connecting outer circumferential corner portions 1132a, 1132c of second ends 1112a-1112b of magnet holes 817a-817b, and inner circumferential corner portions 1132a, 1132c of second ends 1112a-1112b of magnet holes 817a-817b. b10 and 11A, the reference numerals 821a and 831a are arranged side by side, which indicates an area surrounded by a straight line 1141b connecting the magnet holes 817a, 817b, and the second ends 1112a-1112b of the two magnet holes 817a-817b. The inter-magnet bridge portion 821a coincides with this bridge outer edge portion 831a. This is why the reference numerals 821a and 831a are shown side by side in Fig. 10 and Fig. 11A.

[0121] Furthermore, in the example shown in FIGS. 11B and 11C, the bridge outer edge is defined as follows. In the example shown in FIG. 11B, the bridge outer edge portion 831b is an area surrounded by a straight line 1141c connecting the outer circumferential corner portions 1132e, 1132h of the second ends 1112c, 1112d of the magnet holes 817a, 817b, a straight line 1141d connecting the inner circumferential corner portions 1132g, 1132j of the second ends 1112c, 1112d of the two magnet holes 817a, 817b, and the second ends 1112c, 1112d of the two magnet holes 817a, 817b. The inter-magnet bridge portion 821i coincides with this bridge outer edge portion 831b. This is what is meant by the reference symbols 821i and 831b being shown side by side in FIG. 11B.

[0122] In the example shown in FIG. 11C, the bridge outer edge portion 831c is an area surrounded by a straight line 1141f connecting the outer circumferential corner portions 1132k, 1132m of the second ends 1112e-1112f of the magnet holes 817a-817b, a straight line 1141g connecting the inner circumferential corner portions 1132l, 1132n of the second ends 1112e-1112f of the two magnet holes 817a-817b, and the second ends 1112e-1112f of the two magnet holes 817a-817b. The inter-magnet bridge portion 821j coincides with this bridge outer edge portion 831c. This is what is meant by the reference symbols 821j and 831c being shown side by side in FIG. 11C.

[0123] The outer portion 822a is a region of the outer periphery where the soft magnetic material is present. a10 and 11A, the outer peripheral portion is a region surrounded by third ends 1113a-1113b of two magnet holes 817a-817b in which permanent magnets 812a-812b are installed, and outer circumferential surface 818 of rotor core 811. 10 In this embodiment, the outer peripheral portion 832a is illustrated as being made up of only soft magnetic material (not including regions other than the soft magnetic material, such as a flux barrier). Therefore, the outer portion 822a coincides with the outer peripheral portion 832a. However, the outer peripheral portion 832a may include regions other than the soft magnetic material, such as a flux barrier. In this case, the outer portion 822a is the region of the outer peripheral portion 832a excluding the regions other than the soft magnetic material. The number of the outer portions 822a to 822h is equal to the number of poles of the rotor 810 (8 in this embodiment).

[0124] Specifically, in the example shown in Fig. 11A, the outer peripheral edge portion 832a is an area surrounded by a straight line 1141a connecting the outer peripheral corner portions 1132a, 1132c of the second ends 1112a-1112b of the magnet holes 817a-817b, the third ends 1113a-1113b of the two magnet holes 817a-817b, and the outer peripheral surface 818 of the rotor core 811. The outer portion 822a coincides with this outer peripheral edge portion 832a. This is what is meant by the fact that the reference characters 822a and 832a are shown side by side in Figs. 10 and 11A.

[0125] Also, in the example shown in Figures 11B and 11C, the outer perimeter is defined as follows. In the example shown in FIG. 11B, the outer periphery 832b is located at the magnet hole 817. c ~817 d The outer periphery 818 of the rotor core 811 is defined as a region surrounded by a straight line 1141c connecting outer periphery corners 1132e, 1132h of the second ends 1112c-1112d, third ends 1113c-1113d of the two magnet holes 817c-817d, and the outer periphery 818 of the rotor core 811. The outer portion 822i coincides with the outer periphery 832b. This is why the reference symbols 822i and 832b are shown side by side in FIG. 11B.

[0126] In the example shown in FIG. 11C, the outer periphery 832c is located at the magnet hole 817. e ~817 f The outer circumferential surface 818 of the rotor core 811 is an area surrounded by a straight line 1141f connecting the outer circumferential corner portions 1132k, 1132m of the second ends 1112e-1112f, the third ends 1113e-1113f of the two magnet holes 817e-817f, and the outer circumferential surface 818 of the rotor core 811. The outer portion 822j coincides with the outer circumferential surface 832c. This is why the reference symbols 822j and 832c are shown side by side in FIG. 11C.

[0127] The inner portion 823a is a region of the inner outer edge portion where a soft magnetic material is present. The inner outer edge portion is a region of soft magnetic material connected to the inter-magnet bridge portion 821a on the inner circumferential side of the inter-magnet bridge portion 821a. In the example shown in FIG. 10 and FIG. 11A, the inner outer edge portion is a region surrounded by the fourth ends 1114a-1114b of the two magnet holes 817a-817b in which the permanent magnets 812a-812b are installed, the outer circumferential surface 818 of the rotor core 811, and the inner circumferential surface 819 of the rotor core 811. 10 In this embodiment, the case where only soft magnetic material is present in the inner outer edge portion 833a is exemplified. The presence of only soft magnetic material means that no regions other than the soft magnetic material, such as flux barriers, are included. Therefore, the inner portion 823a coincides with the inner outer edge portion 833a. However, the inner outer edge portion 833a may include regions other than the soft magnetic material, such as flux barriers. In this case, the inner portion 823a is the region of the inner outer edge portion 833a excluding regions other than the soft magnetic material. Also, as shown in FIG. 10 In the example shown in FIG. 1, the number of the inner portions 823a is 1. The inner portions 823a do not necessarily have to be surrounded by the outer peripheral surface 818 of the rotor core 811. For example, the outer peripheral flux barriers 813a of the mutually adjacent poles ~813b (Outer flux barrier space 1123a ~1123b When rotor core 811 is configured so that there is no soft magnetic material between inner portion 823 a and outer peripheral surface 818 of rotor core 811 .

[0128] Specifically, in the example shown in Fig. 11A, the inner outer edge portion 833a is an area surrounded by a straight line 1141b connecting inner corner portions 1132b, 1132d of the second ends 1112a-1112b of the two magnet holes 817a-817b in which the permanent magnets 812a-812b are installed, the fourth ends 1114a-1114b of the two magnet holes 817a-817b, the outer peripheral surface 818 of the rotor core 811, and the inner peripheral surface 819 of the rotor core 811. The inner portion 823a coincides with this inner outer edge portion 833a. This is what is meant by the fact that the reference symbols 823a and 833a are shown side by side in Figs. 10 and 11A.

[0129] Also, in the example shown in Figures 11B and 11C, the inner outer edge is defined as follows. In the example shown in FIG. 11B, the inner peripheral edge portion 833b is formed at the inner corner portion 1132 of the second ends 1112c to 1112d of the two magnet holes 817c to 817d in which the permanent magnets 812a to 812b are disposed. g , 1132 j Straight line connecting 1141 d 11B, the fourth ends 1114c-1114d of the two magnet holes 817c-817d, the outer circumferential surface 818 of rotor core 811, and the inner circumferential surface 819 of rotor core 811. Inner portion 823b coincides with this inner outer edge portion 833b. This is meant by the fact that reference symbols 823b and 833b are shown side by side in FIG. 11B.

[0130] In the example shown in Fig. 11C, the inner outer edge portion 833c is an area surrounded by a straight line 1141g connecting inner corner portions 1132l, 1132n of the second ends 1112e-1112f of the two magnet holes 817e-817f in which the permanent magnets 812a-812b are installed, the fourth ends 1114e-1114f of the two magnet holes 817e-817f, the outer peripheral surface 818 of the rotor core 811, and the inner peripheral surface 819 of the rotor core 811. The inner portion 823c coincides with this inner outer edge portion 833c. This is what is meant by the reference symbols 823c and 833c being shown side by side in Fig. 11C.

[0131] Next, the inter-magnet bridge portion 82 1 of The width w will now be described. Inter-magnet bridge portion 82 1 of The width w is represented by the length of the portion of the bridge width defining lines 1142a-1142c that overlaps with the soft magnetic material in the rotor core cross section. As shown in Fig. 11A-11C, the bridge width defining lines 1142a-1142c are straight lines that connect the second ends 1112a-1112b, 1112c-1112d, 1112e-1112f of the two magnet holes 817a-817b, 817c-817d, 817e-817f in which the permanent magnets 812a-812b are installed, so as to minimize the length of overlap with the soft magnetic material.

[0132] Specifically, in the example shown in FIG. 11A, the straight line connecting the second ends 1112a-1112b of the two magnet holes 817a-817b in which the permanent magnets 812a-812b are installed so as to minimize the length of overlap with the soft magnetic material is the straight line 1142a, which coincides with the above-mentioned straight line 1141a. In FIG. 11A, the reference symbols 1141a and 1142a are shown side by side to indicate this. In this case, the width w of the inter-magnet bridge portion 821a is the length of the portion of the bridge width defining line 1142a that overlaps with the soft magnetic material in the rotor core cross section. In the example shown in FIG. 11A, the entire bridge width defining line 1142a overlaps with the soft magnetic material. Therefore, the width w of the inter-magnet bridge portion 821a is equal to the length of the bridge width defining line 1142a. When a hole is formed in the inter-magnet bridge portion so that a part of the bridge width defining line overlaps with the soft magnetic material, the width w of the inter-magnet bridge portion is the length of the part of the bridge width defining line that overlaps with the soft magnetic material. Note that the length of the part of the bridge width defining line that overlaps with the soft magnetic material is the length of the bridge width defining line minus the length of the part of the bridge width defining line that does not overlap with the soft magnetic material.

[0133] In the example shown in FIG. 11B, the straight line connecting the second ends 1112c-1112d of the two magnet holes 817c-817d in which the permanent magnets 812a-812b are installed so as to have the shortest overlapping length with the soft magnetic material is the straight line 1142b, which coincides with the above-mentioned straight line 1141e. In FIG. 11B, the reference symbols 1141e and 1142b are shown side by side to indicate this. Therefore, the bridge width defining line is the straight line 1142b. In this case, the width w of the inter-magnet bridge portion 821i is the length of the portion of the bridge width defining line 1142b that overlaps with the soft magnetic material in the rotor core cross section. In the example shown in FIG. 11B, the entire bridge width defining line 1142b overlaps with the soft magnetic material. Therefore, the width w of the inter-magnet bridge portion 821i is equal to the length of the bridge width defining line 1142b.

[0134] In the example shown in FIG. 11C, the straight line connecting the second ends 1112e-1112f of the two magnet holes 817e-817f in which the permanent magnets 812a-812b are placed so as to have the shortest overlapping length with the soft magnetic material is the straight line 1142c, which coincides with the above-mentioned straight line 1141f. In FIG. 11C, the reference symbols 1141f and 1142c are shown side by side to indicate this. Therefore, the bridge width defining line is the straight line 1142c. In this case, the width w of the inter-magnet bridge portion 821j is the length of the portion of the bridge width defining line 1142c that overlaps with the soft magnetic material in the rotor core cross section. In the example shown in FIG. 11C as well, the entire bridge width defining line 1142c overlaps with the soft magnetic material. Therefore, the width w of the inter-magnet bridge portion 821j is equal to the length of the bridge width defining line 1142c.

[0135] Width w of inter-magnet bridge part 821 determined as described above is preferably equal to or less than 0.02 times the diameter of rotor core 811. If width w of inter-magnet bridge part 821 exceeds 0.02 times the diameter of rotor core 811, the magnetic flux passing through inter-magnet bridge part 821 increases, resulting in an increase in return magnetic flux included in the magnetic flux passing through inter-magnet bridge part 821. Therefore, the effect of increasing the torque of rotor 810 due to magnetic flux that does not become return magnetic flux (see magnetic fluxes φ13, φ14 shown in FIG. 5B) is reduced.

[0136] The width w of the inter-magnet bridge portion 821 is the length w determined by the following formula (1): min It is preferable to exceed . w min =ρ×S×r g ×ω÷Ys (1) Here, ρ is the density (kg / m 3 ) is determined in advance, for example, according to the specifications of the IPMSM 800. Ys is the yield stress (Pa) of the soft magnetic material constituting the soft magnetic body part 820 at room temperature.

[0137] The yield stress (Ys) is determined in advance, for example, according to the specifications of the soft magnetic material. The yield stress (Ys) may be a measured value. When a measured value is adopted as the yield stress (Ys), for example, the following may be used. First, a JIS No. 5 test piece is taken from the center of the soft magnetic material in the thickness direction. Then, the tensile test piece is subjected to a tensile test based on the description of JIS Z 2241:2011 to measure the yield stress (Ys). At this time, the rolling direction of the tensile test piece is set as the tensile direction. In detail, when the upper yield point and the lower yield point described in JIS Z 2241:2011 are measured by the tensile test, the yield stress (Ys) may be the upper yield point. On the other hand, in the case of a material in which the yield phenomenon does not clearly appear by the tensile test, the yield stress (Ys) may be the 0.2% proof stress measured by the offset method described in JIS Z 2241:2011.

[0138] S is the area (m 2 ) is. gis the radial distance (m) from the center of rotation (rotation axis 0) of rotor 810 (rotor core 811) to the position of center of gravity G in the rotor core cross section of external force influenced portion 824 (see line 1178 connecting center of gravity G and rotation axis 0 in the rotor core cross section of external force influenced portion 824 in Figs. 11A to 11C). The position of center of gravity G is determined as a point where a resultant force of gravity acting on each part of external force influenced portion 824 acts based on the definition of center of gravity. Note that, for convenience of explanation and notation, Figs. 11A to 11C show approximate positions of centers of gravity G of external force influenced portions 824a to 824c. ω is the angular velocity (rad / sec) of rotor 810 when rotating at the maximum rotation speed. The maximum rotation speed of rotor 810 is the upper limit of the rotation speed of rotor 810 allowed in IPMSM800, and is determined in advance by the specifications of IPMSM800. If the width w of the inter-magnet bridge portion 821 is too large, the torque decreases. Therefore, the length w determined by the formula (1) is set to be min It is preferable that the amount of the saturation is 3.0 times or less.

[0139] Here, the external force influence portion 824 is a region of soft magnetic material surrounded by the third ends 1113 of the two magnet holes 817a-817b in which the permanent magnets 812a-812b are installed at the same pole, the outer peripheral surface 818 of the rotor core 811 (soft magnetic material portion 820), and the bridge width defining line 1142. In the example shown in FIG. 11A, the external force influence portion 824a is a region of soft magnetic material surrounded by the third ends 1113a-1113b of the two magnet holes 817a-817b in which the permanent magnets 812a-812b are installed, the outer peripheral surface 818 of the rotor core 811, and the bridge width defining line 1142a.

[0140] In the example shown in FIG. 11B, the external force influenced portion 824b is a region of soft magnetic material surrounded by the third ends 1113c-1113d of the two magnet holes 817c-817d in which the permanent magnets 812a-812b are installed, the outer peripheral surface 818 of the rotor core 811, and the bridge width defining line 1142b.

[0141] In the example shown in FIG. 11C, the external force influenced portion 824c is a region of soft magnetic material surrounded by the third ends 1113e-1113f of the two magnet holes 817e-817f in which the permanent magnets 812a-812b are installed, the outer peripheral surface 818 of the rotor core 811, and the bridge width defining line 1142c. The number of external force influenced parts 824 included in one rotor 810 is equal to the number of poles of the rotor 810 (8 in this embodiment). S in formula (1) is not the total area of ​​these eight external force influenced parts 824 in the rotor core cross section, but the area of ​​one external force influenced part 824 in the rotor core cross section.

[0142] In rotor core 811, the area where stress is most concentrated when rotor 810 (rotor core 811) is rotating is the area of ​​soft magnetic material located at the position where bridge width defining lines 1142a to 1142c overlap. In the following description, this area will be referred to as the stress concentration area as necessary. When width w of inter-magnet bridge portion 821 is w min When the width w of the inter-magnet bridge portion 821 is equal to the w in equation (1), the stress generated in the stress concentration area when the rotor 810 (rotor core 811) is rotating at the maximum rotation speed is (theoretically) equal to the yield stress of the soft magnetic material. Therefore, in order to prevent the stress concentration area from breaking when the rotor 810 (rotor core 811) is rotating at the maximum rotation speed, the width w of the inter-magnet bridge portion 821 is equal to the w in equation (1). min It is preferable to make it greater than .

[0143] (calculation example) Next, a calculation example will be described. In this calculation example, the magnetic flux density vector, eddy current vector, and torque in each micro-region (mesh) of the rotor core when the IPMSM, in which two permanent magnets per pole are arranged in a V-shape as shown in FIG. 8, is operated (rotated) according to electromagnetic field analysis conditions including excitation conditions are calculated by performing electromagnetic field analysis using the finite element method. Note that the torque is Maxwell stress. In addition, the stress vector in each micro-region (mesh) of the rotor core when the IPMSM is operated (rotated) according to stress analysis conditions including physical property values ​​such as Young's modulus and Poisson's ratio is calculated by performing stress analysis using the finite element method. The electromagnetic field analysis and stress analysis methods using the finite element method are common methods, so detailed explanations thereof will be omitted here. Note that in each calculation example, the conditions other than the flux barrier and recessed parts of the rotor core are the same, including the electromagnetic field analysis conditions. In this calculation example, the residual magnetic flux density of the permanent magnet is set to 0.4 T as a condition for the electromagnetic field analysis. The excitation current flowing through the stator coil was a three-phase AC current with a peak value of 20 A and a frequency of 50 Hz. The lead angle was 30°. The diameter of the rotor core was 27 mm in both cases. The number of slots in the stator core was 24.

[0144] First, as explained in the (First Findings) section of the (History) column, Table 1 shows the results of verifying the effect of positioning the open end front corner portions 1131a, 1131c on the rotor core cross section rearward in the rotational direction of rotor core 111 relative to reference positions 831a, 831b.

[0145] [Table 1]

[0146] In Table 1, the θf column indicates the movement angle θf (°) of the outer periphery flux barrier on the front side shown in FIG. 11A. Also, in Table 1, the θb column indicates the movement angle θb (°) of the outer periphery flux barrier on the rear side shown in FIG. 11A. Also, in Table 1, the reference position indicates that the movement angle θf of the outer periphery flux barrier on the front side and the movement angle θb of the outer periphery flux barrier on the rear side are 0°. Also, in Table 1, the recess column indicates the presence or absence of a recess.

[0147] As defined in this embodiment, the movement angle θf of the outer periphery flux barrier on the front side and the movement angle θb of the outer periphery flux barrier on the rear side are angles formed by two straight lines (e.g., straight lines 1171 and 1172), and therefore take values ​​equal to or greater than 0. For example, a polar coordinate system is defined such that the positive direction of the deflection angle θ is the same as the rotation direction of the rotor, and the movement angle θf of the outer periphery flux barrier on the front side and the movement angle θb of the outer periphery flux barrier on the rear side are expressed in the polar coordinate system. In this case, when these movement angles θf and θb are each negative, it is expressed that they are located on the negative side (rear side in the rotation direction) with respect to the reference position. The above also applies to the recess opening angle θc.

[0148] The torque increase / decrease column shows a percentage value representing the increase / decrease in the torque of the rotor when the movement angle θf of the front outer flux barrier and the movement angle θb of the rear outer flux barrier are both 0°. Therefore, a larger value in the torque increase / decrease column indicates that the torque of the rotor is greater than the torque of the rotor when the movement angle θf of the front outer flux barrier and the movement angle θb of the rear outer flux barrier are both 0°.

[0149] 12A and 12B are diagrams showing the configuration of the rotor (rotor cross section) for which analysis is performed in the cases of numbers 9 and 19 in Table 1, respectively. FIG. 12C and FIG. 12D are diagrams showing the configuration of the rotor (rotor cross section) for which analysis is performed in the cases of numbers 23 and 24 in Table 1, respectively. As in FIG. 1, FIG. 12A to FIG. 12D also show one of four regions (the region of the IPMSM that constitutes two poles of the rotor) obtained by dividing a cross section perpendicular to the rotation axis 0 of the IPMSM into four equal parts. Note that if an electromagnetic field analysis is performed only on this one region, the results of the electromagnetic field analysis of the entire rotor cross section can be obtained by utilizing the rotational symmetry of the IPMSM. As described above, in FIG. 12A to FIG. 12D, as in FIG. 1, only the part that constitutes one pole of the rotor is given a reference symbol, and the reference symbols of the parts that constitute the other poles of the rotor are omitted.

[0150] 12A to 12D, as described in this embodiment, outer periphery flux barriers 1201a to 1201e reach and open to outer periphery surfaces 1211a to 1211d of the rotor core in the rotor core cross section. Also, inter-magnet flux barriers 1202a to 1202b are not connected, and soft magnetic material (inter-magnet bridge portion) exists between inter-magnet flux barriers 1202a to 1202b.

[0151] As mentioned above, in this calculation example, the number of slots in the stator core N slot Therefore, the reference position movement angle θa is π / 12rad=15° (θa(rad)=2π / N slot As described in this embodiment, the movement angle θf of the outer periphery flux barrier on the front side is preferably set to θa / 24 or more and 15θa / 24 or less, and more preferably within the range of θa / 3±θa / 24. In this calculation example, the movement angle θf of the outer periphery flux barrier on the front side is preferably set to 0.625° or more and 9.375° or less, and more preferably within the range of 5±0.625°.

[0152] In Table 1, in the cases of Nos. 2 to 16 in which the movement angle θf of the outer periphery flux barrier on the front side is 0.625° or more and 9.375° or less, the torque increase / decrease shows a positive value, and it is understood that the torque of the rotor can be improved. In addition, in the cases of Nos. 8 to 10 in which the movement angle θf of the outer periphery flux barrier on the front side is within the range of 5±0.625°, it is understood that the torque of the rotor can be further improved. In particular, in the case of No. 9 in which the movement angle θf of the outer periphery flux barrier on the front side is 5°, which is the central value within the range of 5±0.625°, the value of the torque increase / decrease shows a maximum value. On the other hand, in the case of No. 17 in which the movement angle θf of the outer periphery flux barrier on the front side is more than 9.375°, the torque increase / decrease shows a negative value, and it is understood that the torque of the rotor cannot be improved.

[0153] Moreover, the movement angle θb of the outer peripheral flux barrier on the rear side is preferably θa / 24 to θa / 8, and is preferably within the range of θa / 12±θa / 24. In this calculation example, the movement angle θb of the outer peripheral flux barrier on the rear side is preferably 0.625° to 1.875°, and is preferably within the range of 1.25±0.625°.

[0154] In Table 1, in the cases of Nos. 18 to 21 where the movement angle θb of the outer circumferential flux barrier on the rear side is between 0.625° and 1.875°, the torque increase / decrease is a positive value, and it is understood that the torque of the rotor can be improved. In addition, in the cases of Nos. 18 to 20 where the movement angle θb of the outer circumferential flux barrier on the rear side is within the range of 1.25±0.625°, it is understood that the torque of the rotor can be further improved. In particular, in the case of No. 19 where the movement angle θb of the outer circumferential flux barrier on the rear side is 1.25°, which is the central value within the range of 1.25±0.625°, the value of the torque increase / decrease is a local maximum value. On the other hand, in the cases of Nos. 21 and 22 where the movement angle θb of the outer circumferential flux barrier on the rear side is greater than 1.875°, the torque increase / decrease is close to 0 or is a negative value, and it is understood that the torque of the rotor cannot be improved.

[0155] From the results of numbers 2 to 22 in Table 1 above, it can be seen that the torque of the rotor can be improved even if only one of the movement angle θf of the front outer periphery flux barrier and the movement angle θb of the rear flux barrier is within the range described in this embodiment.

[0156] However, in Table 1, in the case of number 23 where the movement angle θf of the outer circumferential flux barrier on the front side is determined as shown in number 9 and the movement angle θb of the rear side flux barrier as shown in number 19 are both within the ranges defined in this embodiment, the torque increase / decrease value is larger than those of numbers 2 to 16 and 18 to 20, and it can be seen that the rotor torque can be further improved.

[0157] As described in this embodiment, the recess opening angle θc is preferably θa / 8 or more and 25θa / 24θa or less, and more preferably within the range of 3θa / 4±θa / 12. In this calculation example, the reference position movement angle θa is 2π / 24 (rad)=15(°). Therefore, the recess opening angle θc is preferably 1.975° or more and 15.625° or less, and more preferably within the range of 11.25°±1.25°. Furthermore, the maximum recess depth Cd is preferably 0.01 times the diameter of the rotor core or more and 0.1 times the diameter of the rotor core. Double It is preferable that the range is as follows. As described above, in this calculation example, the diameter of each rotor core is 27 mm. Number 24 in Table 1 is the same as number 27 in Table 2 described later. The recess opening angle θc of the recess 1242a shown in FIG. 12D is 3.125°. In addition, the maximum recess depth Cd of the recess 1242a shown in FIG. 12D is 0.05 times the diameter of the rotor core.

[0158] In Table 1, number 24 is the result under the same conditions as number 23, except that the above-mentioned recessed portion 1242a was provided. Comparing numbers 23 and 24, it can be seen that by providing recessed portion 1242a having the recessed portion opening angle θc and maximum recessed portion depth Cd within the range described in this embodiment, the torque of the rotor can be further improved.

[0159] Next, as explained in the (Second Findings) section of the (Background) section, Table 2 shows the results of verifying the effect of providing recess 815a in a position facing teeth 123a, 123b, which have a magnetic flux density higher than the minimum magnetic flux density, in the region of outer surface 818 of rotor core 811.

[0160] [Table 2]

[0161] In Table 2, the θc column and the Cd column show the recess opening angle θc and the maximum recess depth Cd shown in FIG. 11A, respectively. In Table 2, the rotor diameter*value is the value multiplied by the diameter of the rotor core. The other notations in Table 2 are the same as in Table 1. Note that number 23 shown in Table 1 is listed again in Table 2.

[0162] Fig. 12E is a diagram showing the configuration (rotor cross section) of the rotor for which analysis is performed in number 36 of Table 2. As described above, Fig. 12D is a diagram showing the configuration (rotor cross section) of the rotor for which analysis is performed in number 27 of Table 2 (number 24 of Table 1). Number 36 of Table 2 differs from number 27 of Table 2 (number 24 of Table 1) in the recess opening angle θc of recesses 1242a-1242b.

[0163] As described above, in this calculation example, the recess opening angle θc is preferably set to 1.975° or more and 15.625° or less, and more preferably within the range of 11.25°±1.25°. In addition, the recess depth maximum value Cd is set to 0.01 times or more and 0.1 times or less the diameter of the rotor core. Double It is preferable to set it within the following range:

[0164] In Table 2, comparing No. 23 with No. 25, it can be seen that when the recess opening angle θc is below 1.975° as in No. 25, providing the recess does not contribute to improving the torque of the rotor. Similarly, comparing No. 23 with No. 33, it can be seen that when the recess opening angle θc is above 15.625° as in No. 33, providing the recess does not contribute to improving the torque of the rotor. Furthermore, comparing No. 23 with No. 39, it can be seen that when the maximum recess depth Cd is above 0.1 times the diameter of the rotor core as in No. 39, providing the recess does not contribute to improving the torque of the rotor.

[0165] On the other hand, the recess opening angle θc is 1.975° or more and 15.625° or less, and the maximum recess depth Cd is 0.01 times or more and 0.1 times or less the diameter of the rotor core. Double In the following numbers 26 to 32 and 34 to 38, the torque increase / decrease value is larger than that in number 23. Therefore, it can be seen that in numbers 26 to 32 and 34 to 38, the rotor torque can be improved compared to number 23.

[0166] It can also be seen that the torque of the rotor can be further improved in numbers 29 to 30 where the recess opening angle θc is within the range of 11.25°±1.25°. In particular, the torque increase / decrease value is a maximum value in number 30 where the recess opening angle θc is 11.25°, which is the central value within the range of 11.25°±1.25°. It can also be seen that the torque of the rotor can be further improved in numbers 35 to 37 where the recess maximum depth Cd is within the range of 0.04 to 0.07 times the diameter of the rotor core. In particular, the torque increase / decrease value is a maximum value in number 36 where the recess maximum depth Cd is a value near the center within the range of 0.04 to 0.07 times the diameter of the rotor core.

[0167] Furthermore, for example, comparing number 23 with number 36 in Table 2, it can be seen that even if the movement angle θf of the outer circumferential flux barrier on the front side and the movement angle θb of the rear side flux barrier are not within the ranges described in this embodiment, the torque of the rotor can be improved by setting the recess opening angle θc and the maximum recess depth Cd within the ranges described in this embodiment.

[0168] From the above, it can be seen that as long as any one of the movement angle θf of the outer peripheral flux barrier on the front side, the movement angle θb of the rear flux barrier, the recess opening angle θc, and the maximum recess depth Cd is within the range described in this embodiment, the others do not need to be within the range described in this embodiment.

[0169] Next, as explained in the ((Third Findings)) section of the (Background) column, the effects of proactively providing inter-magnet bridge portion 821 and expanding and opening outer periphery flux barrier 813 up to outer periphery surface 818 of rotor core 811 are verified and shown in Table 3.

[0170] [Table 3]

[0171] 12F to 12I are diagrams showing the configurations (rotor cross sections) of the rotors that are the subject of analysis execution for numbers 40 to 43 in Table 3. Note that, in order to verify only the effects in the ((Third Finding)) column, the movement angle θf of the outer periphery-side flux barrier on the front side and the movement angle θb of the rear side flux barrier are not within the ranges described in this embodiment.

[0172] In FIG. 12F, outer periphery flux barriers 1201f-1201g reach outer periphery surface 1211f of the rotor core in the rotor core cross section and are open. Furthermore, inter-magnet flux barriers 1202a-1202b are not connected, and soft magnetic material (inter-magnet bridge portion 1232a) exists between inter-magnet flux barriers 1202a-1202b. In the example shown in FIG. 12F, width w of the inter-magnet bridge portion is 0.3 mm. Furthermore, in the example shown in FIG. 12F, w in equation (1) min is 0.075 mm.

[0173] The shape and size of the inter-magnet flux barriers 1202a-1202b shown in FIG. 12G are the same as the shape and size of the inter-magnet flux barriers 1202a-1202b of the rotor shown in FIG. 12F. Therefore, the shape and size of the inter-magnet bridge portion 1232a of the rotor shown in FIG. 12G are the same as the shape and size of the inter-magnet bridge portion 1232a of the rotor shown in FIG. 12F. Furthermore, the shape and size of the outer periphery flux barriers 1201h-1201i shown in FIG. 12G are the same as the shape and size of the inter-magnet flux barriers 1202a-1202b. In FIG. 12G, the outer periphery flux barriers 1201h-1201i and the inter-magnet flux barriers 1202a-1202b are arranged so that the widths of the outer periphery bridge portion and the inter-magnet bridge portion are approximately equal. Furthermore, outer periphery side flux barriers 1201h to 1201i shown in FIG. 12G do not reach outer periphery surface 1211g of the rotor core in the rotor core cross section and are not open.

[0174] In this calculation example, the width of the outer periphery bridge part is expressed as the length in the direction perpendicular to the direction of magnetic flux flowing through the inter-magnet bridge part in the cross section of the rotor core. The width of the inter-magnet bridge part is the shortest length among the lengths (lengths perpendicular to the direction of magnetic flux flow) of the inter-magnet bridge part.

[0175] In FIG. 12H, a soft magnetic material (inter-magnet bridge portion 1232b) is present between the permanent magnets 1221a and 1221b (inter-magnet flux barriers 1202d and 1202e). 1j ~120 1k The shape and size of the flux barrier between the magnets 12 02d~1202e In FIG. 12H, the outer periphery side flux barriers 1201j to 1201k and the inter-magnet flux barriers 1202d to 1202k are arranged so that the widths of the outer periphery side bridge portions 1231c to 1231d and the width of the inter-magnet bridge portion 1232b are approximately equal. 2 12H are respectively the widths of the outer periphery bridge parts 1231a to 1231b and the width of the inter-magnet bridge part 1232b shown in FIG. 2 Shorter than the width of 32a.

[0176] As described above with reference to Figs. 11A to 11C, the width of the inter-magnet bridge portion is represented by the length of the portion of the bridge width defining line that overlaps with the soft magnetic material in the rotor core cross section. The bridge width defining line is a straight line that connects the second ends of the two magnet holes in which the permanent magnets are installed so that the length of overlap with the soft magnetic material is the shortest. As described above with reference to Figs. 11B and 11C, the positions of both ends of the straight line drawn so that the length of overlap with the soft magnetic material constituting the soft magnetic body portion is the shortest distance are included in the second end. Therefore, in the example shown in Fig. 12H, the length of the straight line that connects the areas between the inter-magnet flux barriers 1202d to 1202e at the shortest distance is the width of the inter-magnetic bridge portion.

[0177] Also, outer periphery side flux barriers 1201j to 1201k shown in FIG. 12H do not reach outer periphery surface 1211h of the rotor core in the rotor core cross section and are not open. Also, inter-magnet flux barriers 1202d to 1202e shown in FIG. 12H are not connected. Therefore, inter-magnet flux barriers 1202 (1202d to 1202e )of There is a soft magnetic material between them (the bridge between the magnets).

[0178] The shapes and sizes of the outer periphery flux barriers 1201h-1201i shown in Fig. 12I are the same as those of the outer periphery flux barriers 1201h-1201i of the rotor shown in Fig. 12G. Therefore, the shapes and sizes of the outer periphery bridge parts 1231a-1231b shown in Fig. 12I are the same as those of the outer periphery bridge parts 1231a-1231b of the rotor shown in Fig. 12G. Also, in Fig. 12I, the number of flux barriers (inter-magnet flux barriers 1202f) on the inner periphery side in the left-right direction Ds from the permanent magnets 1221a-1221b is one.

[0179] In Table 3, as shown in FIG. 12G, the outer bridge portion 1 2 31a~1 2 31b and the inter-magnet bridge portion 1 2 The width of 32a is set to the magnetic stone Bridge section 1 2 The width of the magnetic pole shown in FIG. stone It can be seen that when the width of outer periphery side bridge portions 1231a-1231b and inter-magnet bridge portion 1232a is narrowed as shown in Fig. 12H, the torque of the rotor is lower than when the width of outer periphery side bridge portions 1231c-1231d and inter-magnet bridge portion 1232b are narrowed as shown in Fig. 12H. Also, when outer periphery side bridge portions 1231a-1231b are provided and the inter-magnet bridge portion is eliminated as shown in Fig. 12I, the torque of the rotor is lower than when outer periphery side bridge portions 1231a-1231b and inter-magnet bridge portion 1232a are provided as shown in Fig. 12G, and the width of inter-magnet bridge portion 1232a is narrowed as shown in Fig. 12F. stone The width of the bridge portion 1232a is set to be the same as that of the magnetic pole shown in FIG. stoneHowever, when the inter-magnet bridge portions are eliminated as shown in Fig. 12I, the torque of the rotor is lower than when outer periphery-side bridge portions 1231c-1231d and inter-magnet bridge portion 1232b are provided as shown in Fig. 12H, and the widths of outer periphery-side bridge portions 1231c-1231d and inter-magnet bridge portion 1232b are narrower than the widths of outer periphery-side bridge portions 1231a-1231b and inter-magnet bridge portion 1232a shown in Fig. 12G. It can also be seen that when inter-magnet bridge portion 1232a is provided without providing an outer periphery bridge portion as shown in Fig. 12F, the torque of the rotor is higher than when outer periphery bridge portions 1231a-1231b and inter-magnet bridge portion 1232a are provided as shown in Fig. 12G, and when the widths of outer periphery bridge portions 1231c-1231d and inter-magnet bridge portion 1232b are narrower than the widths of outer periphery bridge portions 1231a-1231b and inter-magnet bridge portion 1232a shown in Fig. 12G, as shown in Fig. 12H. That is, it can be seen that the torque of the rotor is highest when inter-magnet bridge portion 1232a is provided and outer periphery flux barriers 1201f-1201g are opened by expanding to the outer periphery surface of the rotor core as shown in Fig. 12F.

[0180] Table 4 shows the calculation results of the stress for the rotor shown in FIG. 12F and the rotor shown in FIG. 12H. The values ​​shown in Table 4 are calculated as follows. First, the maximum stress value among the calculated values ​​of the stress applied to the rotor core when rotating at the rotation speed shown in the rotation speed column is set as the maximum value of the stress applied to the rotor core when rotating at that rotation speed. Then, the maximum value of the stress applied to the rotor core when rotating at that rotation speed is normalized (made dimensionless) by setting the maximum value of the stress applied to the rotor core of the rotor shown in FIG. 12H when the rotor rotates at 20,000 rpm as 100. The normalized values ​​are shown in each column of Table 4.

[0181] [Table 4]

[0182] As shown in Table 3, the torque of the rotor shown in FIG. 12G and the torque of the rotor shown in FIG. 12I are smaller than those of the rotors shown in FIG. 12F and FIG. 12H. Therefore, the rotors shown in FIG. 12F and FIG. 12H are electromagnetically superior to the rotor shown in FIG. 12I. Therefore, using Table 4, the rotor shown in FIG. 12F is compared with the rotor shown in FIG. 12H from a mechanical viewpoint. The width of the inter-magnet bridge portion 1232a shown in FIG. 12F is approximately the same as the sum of the widths of the outer periphery bridge portions 1231c to 1231d and the inter-magnet bridge portion 1232b shown in FIG. 12H. However, as shown in Table 4, the maximum value of the stress applied to the rotor core is lower in the rotor shown in FIG. 12F than in the rotor shown in FIG. 12H. Therefore, it can be seen that the rotor shown in FIG. 12F can improve the resistance to centrifugal force more than the rotor shown in FIG. 12H. As described above, it can be said that the rotor (rotor core) shown in FIG. 12F has a shape that is dynamically and electromagnetically superior to the rotors (rotor cores) shown in FIGS. 12G to 12I.

[0183] (summary) As described above, in this embodiment, the positions of the open end front corners 1131a and 1131c are located rearward of the reference positions 831a to 831b in the rotation direction of the rotor core 811 in the rotor core cross section. Here, the open end front corners 1131a and 1131c are the front corners in the rotation direction of the rotor core 811 among the two corners 1131a to 1131b and 1131c to 1131d in the circumferential direction of the rotor core 811 of at least one open end 1111a to 1111b that is installed in the same pole in the rotor core cross section. Also, the reference positions 831a and 831b are reference positions for the magnet holes 817a and 817b that have the open end 1111a and 1111b, respectively. Therefore, the torque of the rotor 810 can be increased.

[0184] In this embodiment, the position of front open end front corner 1131a of front open end 1111a is further rearward in the rotation direction of rotor core 811 than reference position 831a for magnet hole 817a having front open end 1111a. Also, the position of rear open end front corner 1131b of rear open end 1111b is further rearward in the rotation direction of rotor core 811 than reference position 831b for magnet hole 817b having rear open end 1111b. Therefore, it is possible to increase the torque of rotor 810 in which permanent magnets 812a-812b are arranged in a so-called V-shape.

[0185] In this embodiment, the outer periphery flux barrier movement angle θf on the front side is set to θa / 24 or more and 15θa / 24 or less (θa is the reference position movement angle). Therefore, the torque of the rotor 810 can be reliably increased.

[0186] In this embodiment, the movement angle θb of the outer circumferential flux barrier on the rear side is set to be equal to or greater than θa / 24 and equal to or less than θa / 8. Therefore, the torque of the rotor 810 can be reliably increased.

[0187] In this embodiment, the length L1 of the open ends 1111a to 1111b in the circumferential direction of the rotor core 811 is set to be 0.1 to 1.0 times the length L2 of the magnetization direction Dm of the permanent magnets 812a to 812b. Therefore, the return magnetic flux can be reliably suppressed.

[0188] In this embodiment, recessed portion 815a is provided at a position facing, with a gap, teeth 123a, 123b of stator core 121, which is disposed at a position facing, with a gap, outer circumferential surface 818 of rotor core 811. Teeth 123a, 123b are different from teeth 123b, 123d, which have the lowest magnetic flux density among teeth 123a to 123d. This makes it possible to further increase the torque of rotor 810.

[0189] In this embodiment, the recess opening angle θc in the rotor core cross section is set to θa / 8 or more and 25θa / 24θa or less (θa is the reference position movement angle). Therefore, the torque of the rotor 810 can be reliably increased.

[0190] In this embodiment, the maximum recess depth Cd is set to be 0.01 to 0.1 times the diameter of the rotor core 811. Double The range is as follows: Therefore, the torque of the rotor 810 can be reliably increased.

[0191] In this embodiment, the rotor core 811 has a plurality of magnetic poles. stone The magnet holes per pole include two magnet holes 817a-817b each having a first end 1111a-1111b located on the outer periphery side in the left-right direction Ds and a second end 1112a-1112b located on the inner periphery side of the first end 1111a-1111b in the left-right direction Ds. The soft magnetic material part 820 has an inter-magnet bridge part 821a between the second end 1112a-1112b of each of the two magnet holes 817a-817b. The second end 1112a-1112b of the two magnet holes 817a-817b coincide with the end of the inter-magnet flux barrier space 1122a-1122b and are closed. On the other hand, the first end 1111a-1111b of the two magnet holes 817a-817b are open. Therefore, the torque of the IPMSM800 can be further increased.

[0192] Furthermore, in this embodiment, width w of inter-magnet bridge portion 821a is set to 0.02 times the diameter of rotor core 811 or less. Therefore, width w of inter-magnet bridge portion 821a can be further reduced. As a result, the return flux contained in the magnetic flux passing through inter-magnet bridge portion 821a can be further reduced. This makes it possible to increase the magnetic flux that contributes to the torque of rotor 810 (magnetic flux that does not become return flux).

[0193] In this embodiment, the width w of the inter-magnet bridge portion 821a is set to w minTherefore, it is possible to prevent breakage originating from inter-magnet bridge portion 821a due to stress generated by the rotation of rotor 810 (rotor core 811).

[0194] In addition, in this embodiment, the area between the second ends 1112a-1112b of the two magnet holes 817a-817b in which the permanent magnets 812a-812b are installed at the same pole is made of a soft magnetic material, so that there is no space that can become a flux barrier. Therefore, if the size of the area between the second ends 1112a-1112b is the same, the bridge portion (inter-magnet bridge portion 821a) included in the area between the second ends 1112a-1112b can be made wider than when there is an area that becomes a flux barrier in the area between the second ends 1112a-1112b. Therefore, the size of the area between the second ends 1112a-1112b can be made the minimum necessary. This makes it possible to narrow the size of the area per pole of the rotor 810 (rotor core 811), for example.

[0195] In addition, in this embodiment, the residual magnetic flux density of the permanent magnets 812a to 812b at room temperature is set to 0.8 T or less. Therefore, the return magnetic flux included in the magnetic flux passing through the inter-magnet bridge portion 821a can be further reduced. Therefore, the magnetic flux that contributes to the torque of the rotor 810 (magnetic flux that does not become return magnetic flux) can be increased. Furthermore, if the residual magnetic flux density of the permanent magnets 812a to 812b at room temperature is set to 0.4 T or less, the return magnetic flux included in the magnetic flux passing through the inter-magnet bridge portion 821a can be further reduced. Therefore, the magnetic flux that contributes to the torque of the rotor 810 (magnetic flux that does not become return magnetic flux) can be further increased.

[0196] In this embodiment, the permanent magnets 812a to 812b do not contain rare earths, so the torque of the rotor 810 can be increased without using materials that are difficult to obtain.

[0197] (Modification) In the present embodiment, two permanent magnets 812a to 812b are provided per pole, but the number of permanent magnets per pole may be one or three or more.

[0198] However, when the number of permanent magnets is three or more, it is preferable to do as follows. That is, among the ends in the magnetization direction Dm of the permanent magnets installed in the magnet holes having the outer flux barriers for which the movement angle θf of the front outer flux barrier and the movement angle θb of the rear flux barrier need to be determined, it is preferable that no permanent magnets are installed in the region between the end on the outer circumferential surface side of the rotor core (the third end 1113 in the example shown in FIG. 11A) and the outer circumferential surface of the rotor core. In this way, the movement angle θf of the front outer flux barrier and the movement angle θb of the rear flux barrier can be set within the ranges described in this embodiment, and the torque of the rotor can be reliably improved.

[0199] In addition, when one permanent magnet is installed per pole, in the magnet hole in which the permanent magnet is installed, the spaces that serve as flux barriers on both sides of the permanent magnet in the left-right direction Ds become the front flux barrier and the rear flux barrier. In this case, both or one of the front flux barrier and the rear flux barrier have an open end.

[0200] In the present embodiment, an IPMSM is exemplified as an interior permanent magnet rotating electric machine. However, the interior permanent magnet rotating electric machine is not limited to an IPMSM. For example, the interior permanent magnet rotating electric machine may be an interior permanent magnet synchronous generator (IPMSG).

[0201] It should be noted that the above-described embodiments of the present invention are merely examples of the implementation of the present invention, and the technical scope of the present invention should not be interpreted as being limited by these. In other words, the present invention can be implemented in various forms without departing from its technical concept or main features.

[0202] The disclosure of the above embodiment can be, for example, as follows. [Disclosure 1] A rotor core including a soft magnetic portion formed using a soft magnetic material and having at least one magnet hole per pole, the magnet hole has a space serving as a front flux barrier and a space serving as a rear flux barrier on both sides in a left-right direction perpendicular to a magnetization direction of the permanent magnet installed in the magnet hole and a direction parallel to a rotation axis serving as a center of rotation, at least one of the space serving as the front side flux barrier and the space serving as the rear side flux barrier has an open end portion that is open on an outer circumferential surface of the rotor core, in a cross section perpendicular to the rotation axis, the front flux barrier is located forward of the rear flux barrier in a rotation direction of the rotor core, before Note a position of an open end front corner portion of at least one of the open ends installed on the same pole of the rotor is located rearward in a rotation direction of the rotor core from a reference position for the magnet hole having the open end, In the cross section, the open end front corner portion is a front corner portion in a rotation direction of the rotor core out of two corner portions in a circumferential direction of the rotor core of at least one of the open ends installed on the same pole of the rotor, In the cross section, a reference position for the magnet hole having the open end is a position of an intersection between a straight line passing through a permanent magnet reference end, which is one of the ends of the permanent magnets installed in the magnet hole and the rotation axis, and an outer circumferential surface of the rotor core, A rotor core, wherein in the cross section, the permanent magnet reference end of the permanent magnet closest to the open end is the end of the permanent magnet that is located at the furthest circumferential distance from a straight line passing through the rotation axis and the circumferential center position of a pole region including the permanent magnet closest to the open end, and the circumferential distance from a straight line passing through the rotation axis and the circumferential center position of a pole region including the permanent magnet closest to the open end is a distance determined on the side where the open end is located, of the front side and the rear side in the rotation direction of the rotor core. [Disclosure 2] A rotor core as described in Disclosure 1, wherein, in the cross section, the positions of the open end front corner portions of all the open ends installed on the same pole of the rotor are located rearward in the rotation direction of the rotor core than a reference position for the magnet hole having that open end. [Disclosure 3] The rotor core has a plurality of magnetic poles. stone having a hole, the plurality of magnet holes include a front side magnet hole located on a front side in the rotation direction and a rear side magnet hole located on a rear side in the rotation direction, the space of the front side magnet hole that serves as the front side flux barrier is an outer periphery side flux barrier that is located forward in the rotation direction and on the outer periphery side of the rotor core relative to the space of the front side magnet hole that serves as the rear side flux barrier, the space of the rear-side magnet hole that serves as the rear-side flux barrier is an outer-periphery-side flux barrier that is located rearward in the rotation direction and toward the outer periphery of the rotor core relative to the space of the rear-side magnet hole that serves as the front-side flux barrier, at least one of a space that serves as the front-side flux barrier of the front-side magnet hole and a space that serves as the rear-side flux barrier of the rear-side magnet hole has the open end, In the cross section, the open end front corner portion has at least one of a front side open end front corner portion and a rear side open end front corner portion, In the cross section, the front corner portion of the front open end portion is a front corner portion in the rotation direction of one of two corner portions of the front open end portion in a circumferential direction of the rotor core, In the cross section, the front open end portion is the open end portion of a space that serves as the front flux barrier and that is included in the front magnet hole, In the cross section, the rear open end Front corner is a front corner portion in the rotation direction of one of two corner portions of the rear open end portion in the circumferential direction of the rotor core, In the cross section, the rear open end The part the open end of the space serving as the rear-side flux barrier that the rear-side magnet hole has, In the cross section, the permanent magnet reference end has at least one of a front permanent magnet end and a rear permanent magnet end, In the cross section, the front-side permanent magnet end portion is an end portion of the permanent magnet installed in the front-side magnet hole that is located at a position closest to the front side in the direction of rotation, In the cross section, the rear-side permanent magnet end is an end of the permanent magnet installed in the rear-side magnet hole that is located at the rearmost position in the rotation direction, In the cross section, the reference position has at least one of a front reference position and a rear reference position, In the cross section, the front-side reference position is a position of an intersection between a straight line passing through the front-side permanent magnet end and the rotation axis and an outer circumferential surface of the rotor core, The rotor core according to Disclosure 1 or 2, wherein, in the cross section, the rear side reference position is a position of an intersection between a straight line passing through the rear side permanent magnet end and the rotation axis and an outer peripheral surface of the rotor core. [Disclosure 4] the open end front corner portion has the front side open end front corner portion and the rear side open end front corner portion, the permanent magnet reference end has the front permanent magnet end and the rear permanent magnet end, the reference position includes the front reference position and the rear reference position, A rotor core as described in Disclosure 3, wherein the space in the front magnet hole that serves as the front flux barrier and the space in the rear magnet hole that serves as the rear flux barrier each have the open end. [Disclosure 5] in the cross section, an angle between a line passing through the rotation axis and an open-end front corner portion that is located forward in the rotation direction from the circumferential center of the same pole among the open-end front corner portions, and a line passing through the rotation axis and the reference position for the magnet hole having the open end having the open end, the open-end front corner portion being one of the corner portions, is equal to or greater than θa / 24 and is equal to or less than 15θa / 24, θa is a movement angle (rad) from the reference position around the rotation axis, θa is 2π / N slot It is calculated as N slot is the number of slots of a stator core disposed at a position facing the outer circumferential surface of the rotor core with a gap therebetween. [Disclosure 6] in the cross section, an angle formed by a line passing through the rotation axis and an open-end front corner portion that is located rearward in the rotation direction from the circumferential center of the same pole among the open-end front corner portions, and a line passing through the rotation axis and the reference position for the magnet hole having the open end having the open end as one of its corner portions is equal to or greater than θa / 24 and equal to or less than θa / 8, θa is a movement angle (rad) from the reference position around the rotation axis, θa is 2π / N slot It is calculated as N slot is the number of slots of a stator core disposed at a position facing the outer circumferential surface of the rotor core with a gap therebetween. [Disclosure 7] A rotor core described in any one of Disclosures 1 to 6, wherein the circumferential length of the open end is 0.1 to 1.0 times the length in the magnetization direction of the permanent magnet installed in the magnet hole having the open end. [Disclosure 8] the soft magnetic material portion further includes a recessed portion having an open end portion that is open on an outer circumferential surface of the rotor core as a recessed portion different from the space that serves as the flux barrier, A rotor core as described in any one of Disclosures 1 to 7, wherein the recessed portion is located at a position facing, with a gap, a tooth other than a tooth having the lowest magnetic flux density among teeth of a stator core installed at a position facing, with a gap, the outer peripheral surface of the rotor core. [Disclosure 9] in the cross section, an angle between a line passing through the rotation axis and a rear corner of the recess, which is a rear corner in the rotation direction of one of two corners at the open end of the recess, and a line passing through the rotation axis and a front corner of the open end, which is located rearward of the recess in the rotation direction at the same pole as the pole at which the recess is installed, is θa; an angle formed by a line passing through a front corner of the recess, which is a front corner in the rotation direction, and the rotation axis, and a line passing through a rear corner of the recess and the rotation axis, is equal to or greater than θa / 8 and equal to or less than 25θa / 24θa, θa is a movement angle (rad) that is an angle around the rotation axis from a rear reference position that is the position of the intersection between a line passing through a rear permanent magnet end and the rotation axis and the outer circumferential surface of the rotor core in the cross section, The rear-side permanent magnet end portion is an end portion located at the rearmost side in the circumferential direction among the ends of the permanent magnets installed at the same pole, θa is 2π / N slot It is calculated as N slot is the number of slots of the stator core arranged at a position facing the outer circumferential surface of the rotor core with a gap therebetween. [Disclosure 10] The rotor core according to Disclosure 8 or 9, wherein a maximum value of a depth of the recess is within a range of 0.01 to 0.1 times a diameter of the rotor core. [Disclosure 11] The rotor core has a plurality of magnetic poles. stone having a hole, the plurality of magnet holes include a front side magnet hole located on a front side in the rotation direction and a rear side magnet hole located on a rear side in the rotation direction, a space that serves as the front-side flux barrier of the front-side magnet hole is located forward in the rotation direction of a space that serves as the rear-side flux barrier of the front-side magnet hole, The space of the rear magnet hole that serves as the front flux barrier is larger in the rotation direction than the space of the rear magnet hole that serves as the rear flux barrier. before On the side, The soft magnetic material portion has a space that serves as the rear side flux barrier in the front side magnet hole and a space that serves as the rear side flux barrier in the rear side magnet hole. before a bridge portion between the magnets and the space serving as a flux barrier on one side; the front magnet hole has a first end portion that is the open end portion on the front side in the rotation direction with respect to the permanent magnet installed in the front magnet hole, the front magnet hole has a second end on a rear side in the rotation direction with respect to the permanent magnet installed in the front magnet hole, the rear-side magnet hole has a first end portion that is the open end portion on the rear side in the rotation direction with respect to the permanent magnet installed in the rear-side magnet hole, the rear magnet hole has a second end on a forward side in the rotation direction with respect to the permanent magnet installed in the rear magnet hole, A rotor core according to any one of Disclosures 1 to 10, wherein the second ends of the front magnet holes and the rear magnet holes coincide with ends of a space that serves as a flux barrier and are closed. [Disclosure 12] In the cross section, a length of a portion of the bridge-width defining line that overlaps with the soft magnetic material is 0.02 times or less a diameter of the rotor core, A rotor core as described in Disclosure 11, wherein the bridge width defining line is a straight line connecting the second ends of the front side magnet hole and the rear side magnet hole so as to minimize the length of overlap with the soft magnetic material. [Disclosure 13] In the cross section, each of the front side magnet hole and the rear side magnet hole further has a third end portion located on the outer periphery side in the magnetization direction of the permanent magnet installed in the front side magnet hole and the rear side magnet hole, and a fourth end portion located on the inner periphery side of the third end portion in the magnetization direction of the permanent magnet, In the cross section, the length of the bridge width defining line overlapping with the soft magnetic material is w min Exceeding the bridge width defining line is a straight line connecting the second ends of the front side magnet hole and the rear side magnet hole so as to minimize the length of overlap with the soft magnetic material, w min is ρ×S×r g It is calculated as ×ω÷Ys, ρ is the density of the soft magnetic material (kg / m 3 ) and Ys is the yield stress (Pa) of the soft magnetic material at room temperature, S is the area of ​​the part affected by the external force (m 2 ) and the external force affected portion is a region of the soft magnetic material surrounded in the cross section by the third end of the front-side magnet hole located at one end of the bridge width defining line, the third end of the rear-side magnet hole located at the other end of the bridge width defining line, an outer peripheral surface of the soft magnetic material portion, and the bridge width defining line, r g is the radial distance (m) between the position of the center of gravity of the external force affected part in the cross section and the center of rotation, 13. The rotor core according to claim 11 or 12, wherein ω is the angular velocity (rad / sec) of the rotor when rotating at the maximum rotation speed. [Disclosure 14] A rotor core including a soft magnetic portion formed using a soft magnetic material and having at least one magnet hole per pole, The soft magnetic material portion has a recessed portion on an outer circumferential surface, the magnet hole has a first end and a second end in a left-right direction perpendicular to a magnetization direction of a permanent magnet installed in the magnet hole and a direction parallel to a rotation axis that is a center of rotation, At least one of the first end and the second end is an open end, the recessed portion is at a different position from the open end; A rotor core, wherein the recessed portion is located at a position facing, with a gap, a tooth of a stator core other than the tooth having the lowest magnetic flux density, the tooth being installed at a position facing, with a gap, the outer peripheral surface of the rotor core. [Disclosure 15] in the cross section, an angle formed between a line passing through the rotation axis and a rear corner of the recess, which is a rear corner in the rotation direction of the rotor core, and a line passing through the rotation axis and a front corner of the open end, which is located rearward of the recess in the rotation direction for the same pole as the pole on which the recess is provided, is θa; In the cross section, the open end front corner portion is a front corner portion in a rotation direction of the rotor core out of two corner portions in a circumferential direction of the rotor core of at least one of the open ends installed on the same pole of the rotor, an angle formed by a line passing through a front corner of the recess, which is a front corner in the rotation direction, and the rotation axis, and a line passing through a rear corner of the recess and the rotation axis, is equal to or greater than θa / 8 and equal to or less than 25θa / 24θa, θa is a movement angle (rad) that is an angle around the rotation axis from a rear reference position that is the position of the intersection between a line passing through a rear permanent magnet end and the rotation axis and the outer circumferential surface of the rotor core in the cross section, The rear-side permanent magnet end portion is an end portion located at the rearmost side in the circumferential direction among the ends of the permanent magnets installed at the same pole, θa is 2π / N slot It is calculated as Nslot is the number of slots of the stator core arranged at a position facing the outer circumferential surface of the rotor core with a gap therebetween. [Disclosure 16] 16. The rotor core according to Disclosure 14 or 15, wherein the maximum depth of the recess is within a range of 0.01 to 0.1 times the diameter of the rotor core. [Disclosure 17] A rotor core according to any one of Disclosures 1 to 16, A plurality of permanent magnets are disposed in the rotor core; The rotor comprises: [Disclosure 18] The rotor according to Disclosure 17, wherein the permanent magnet has a residual magnetic flux density of 0.8 T or less at room temperature. [Disclosure 19] 19. The rotor according to Disclosure 17 or 18, wherein the permanent magnet does not contain rare earths. [Disclosure 20] A rotor according to any one of Disclosures 17 to 19; A stator; A rotating electric machine comprising: [Industrial Applicability]

[0203] The present invention can be used in, for example, a rotating electric machine.

Claims

1. A rotor core including a soft magnetic portion formed using a soft magnetic material and having at least one magnet hole per pole, the magnet hole has a space serving as a front flux barrier and a space serving as a rear flux barrier on both sides in a left-right direction perpendicular to a magnetization direction of the permanent magnet installed in the magnet hole and a direction parallel to a rotation axis serving as a center of rotation, at least one of the space serving as the front side flux barrier and the space serving as the rear side flux barrier has an open end portion that is open on an outer circumferential surface of the rotor core, in a cross section perpendicular to the rotation axis, the front flux barrier is located forward of the rear flux barrier in a rotation direction of the rotor core, In the cross section, a position of an open end front corner portion of at least one of the open ends installed on the same pole of the rotor is located rearward in a rotation direction of the rotor core with respect to a reference position for the magnet hole having the open end, in the cross section, the open end front corner portion is a front corner portion in a rotation direction of the rotor core out of two corner portions in a circumferential direction of the rotor core of at least one of the open ends provided at the same pole of the rotor, In the cross section, a reference position for the magnet hole having the open end is a position of an intersection between a straight line passing through a permanent magnet reference end, which is one of the ends of the permanent magnets installed in the magnet hole and the rotation axis, and an outer circumferential surface of the rotor core, In the cross section, the permanent magnet reference end of the permanent magnet located closest to the open end is the end of the permanent magnet located at the farthest position in the circumferential direction from a straight line passing through the rotation axis and a center position in the circumferential direction of a pole region including the permanent magnet, a distance in the circumferential direction from a line passing through the rotation axis and a center position in the circumferential direction of one pole region including the permanent magnet closest to the open end is a distance determined on the side where the open end exists, between a front side and a rear side in a rotation direction of the rotor core, A rotor core, in which, in the cross section, the positions of the open end front corner portions of all the open ends installed on the same pole of the rotor are rearward in the rotational direction of the rotor core than a reference position for the magnet hole having that open end.

2. A rotor core formed using a soft magnetic material and having a soft magnetic part with at least one magnet hole per pole, the magnet hole has a space serving as a front flux barrier and a space serving as a rear flux barrier on both sides in a left-right direction perpendicular to a magnetization direction of the permanent magnet installed in the magnet hole and a direction parallel to a rotation axis serving as a center of rotation, at least one of the space serving as the front side flux barrier and the space serving as the rear side flux barrier has an open end portion that is open on an outer circumferential surface of the rotor core, in a cross section perpendicular to the rotation axis, the front flux barrier is located forward of the rear flux barrier in a rotation direction of the rotor core, In the cross section, a position of an open end front corner portion of at least one of the open ends installed on the same pole of the rotor is located rearward in a rotation direction of the rotor core with respect to a reference position for the magnet hole having the open end, in the cross section, the open end front corner portion is a front corner portion in a rotation direction of the rotor core out of two corner portions in a circumferential direction of the rotor core of at least one of the open ends provided at the same pole of the rotor, In the cross section, a reference position for the magnet hole having the open end is a position of an intersection between a straight line passing through a permanent magnet reference end, which is one of the ends of the permanent magnets installed in the magnet hole and the rotation axis, and an outer circumferential surface of the rotor core, In the cross section, the permanent magnet reference end of the permanent magnet located closest to the open end is the end of the permanent magnet located at the farthest position in the circumferential direction from a straight line passing through the rotation axis and a center position in the circumferential direction of a pole region including the permanent magnet, a distance in the circumferential direction from a line passing through the rotation axis and a center position in the circumferential direction of one pole region including the permanent magnet closest to the open end is a distance determined on the side where the open end exists, between a front side and a rear side in a rotation direction of the rotor core, the soft magnetic material portion further includes a recessed portion having an open end portion that is open on an outer circumferential surface of the rotor core as a recessed portion different from the space that serves as the flux barrier, A rotor core, wherein the recessed portion is located at a position facing, with a gap, a tooth of a stator core other than the tooth having the lowest magnetic flux density, the tooth being installed at a position facing, with a gap, the outer peripheral surface of the rotor core.

3. In the cross section, the angle between a line passing through the rotation axis and a rear corner of the recess, which is the rear corner in the direction of rotation of the two corners at the open end of the recess, and a line passing through the rotation axis and a front corner of the open end, which is located rearward of the recess in the direction of rotation at the same pole as the pole at which the recess is installed, is θa, an angle formed by a line passing through a front corner of the recess, which is a front corner in the rotation direction, and the rotation axis, and a line passing through a rear corner of the recess and the rotation axis, is equal to or greater than θa / 8 and equal to or less than 25θa / 24θa, θa is a movement angle (rad) that is an angle around the rotation axis from a rear reference position that is the position of the intersection between a straight line passing through a rear permanent magnet end and the rotation axis and the outer circumferential surface of the rotor core in the cross section, The rear-side permanent magnet end portion is an end portion located at the rearmost side in the circumferential direction among the ends of the permanent magnets installed at the same pole, θa is calculated as 2π / N slot , 3. The rotor core according to claim 2, wherein N slot is the number of slots of a stator core disposed at a position facing the outer circumferential surface of the rotor core with a gap therebetween.

4. A rotor core as described in claim 2 or 3, wherein the maximum depth of the recess is within the range of 0.01 to 0.1 times the diameter of the rotor core.

5. The rotor core has a plurality of magnet holes per pole, the plurality of magnet holes include a front side magnet hole located on a front side in the rotation direction and a rear side magnet hole located on a rear side in the rotation direction, the space of the front side magnet hole that serves as the front side flux barrier is an outer periphery side flux barrier that is located forward in the rotation direction and on the outer periphery side of the rotor core relative to the space of the front side magnet hole that serves as the rear side flux barrier, the space of the rear-side magnet hole that serves as the rear-side flux barrier is an outer-periphery-side flux barrier that is located rearward in the rotation direction and toward the outer periphery of the rotor core relative to the space of the rear-side magnet hole that serves as the front-side flux barrier, at least one of a space that serves as the front-side flux barrier of the front-side magnet hole and a space that serves as the rear-side flux barrier of the rear-side magnet hole has the open end, In the cross section, the open end front corner portion has at least one of a front side open end front corner portion and a rear side open end front corner portion, In the cross section, the front-side open end front corner portion is a front corner portion in the rotation direction of one of two corner portions of the front-side open end in a circumferential direction of the rotor core, In the cross section, the front open end portion is the open end portion of a space that serves as the front flux barrier and that is included in the front magnet hole, In the cross section, the rear-side open end front corner portion is a front corner portion in the rotation direction of one of two corner portions of the rear-side open end portion in a circumferential direction of the rotor core, In the cross section, the rear open end portion is the open end portion of a space that serves as the rear flux barrier and that is included in the rear magnet hole, In the cross section, the permanent magnet reference end has at least one of a front permanent magnet end and a rear permanent magnet end, In the cross section, the front-side permanent magnet end portion is an end portion of the permanent magnet installed in the front-side magnet hole that is located at a position closest to the front side in the direction of rotation, In the cross section, the rear-side permanent magnet end is an end of the permanent magnet installed in the rear-side magnet hole that is located at the rearmost position in the rotation direction, In the cross section, the reference position has at least one of a front reference position and a rear reference position, In the cross section, the front-side reference position is a position of an intersection between a straight line passing through the front-side permanent magnet end and the rotation axis and an outer circumferential surface of the rotor core, 3. The rotor core according to claim 1, wherein, in the cross section, the rear reference position is a position of an intersection between a straight line passing through the rear permanent magnet end and the rotation axis and an outer circumferential surface of the rotor core.

6. the open end front corner portion has the front side open end front corner portion and the rear side open end front corner portion, the permanent magnet reference end has the front permanent magnet end and the rear permanent magnet end, the reference position includes the front reference position and the rear reference position, The rotor core according to claim 5 , wherein the space in the front magnet hole that serves as the front flux barrier and the space in the rear magnet hole that serves as the rear flux barrier each have the open end.

7. in the cross section, an angle between a line passing through the rotation axis and an open-end front corner portion that is located forward in the rotation direction from the circumferential center of the same pole among the open-end front corner portions, and a line passing through the rotation axis and the reference position with respect to the magnet hole having the open end having the open-end front corner portion as one of its corner portions is equal to or greater than θa / 24 and is equal to or less than 15θa / 24, θa is a movement angle (rad) from the reference position around the rotation axis, θa is 2π / N slot It is calculated as N slot 3. The rotor core according to claim 1, wherein n is the number of slots of a stator core disposed at a position facing the outer circumferential surface of the rotor core with a gap therebetween.

8. in the cross section, an angle formed by a line passing through the rotation axis and an open-end front corner portion that is located rearward in the rotation direction from the circumferential center of the same pole among the open-end front corner portions, and a line passing through the rotation axis and the reference position for the magnet hole having the open end having the open end as one of its corner portions is equal to or greater than θa / 24 and equal to or less than θa / 8, θa is a movement angle (rad) from the reference position around the rotation axis, θa is 2π / N slot It is calculated as N slot 3. The rotor core according to claim 1, wherein n is the number of slots of a stator core disposed at a position facing the outer circumferential surface of the rotor core with a gap therebetween.

9. 3. The rotor core according to claim 1, wherein the circumferential length of the open end is 0.1 to 1.0 times the length in the magnetization direction of the permanent magnet installed in the magnet hole having the open end.

10. the soft magnetic material portion further includes a recessed portion having an open end portion that is open on an outer circumferential surface of the rotor core as a recessed portion different from the space that serves as the flux barrier, 2. The rotor core according to claim 1, wherein the recessed portion is located at a position facing, with a gap, a tooth of a stator core other than the tooth having the lowest magnetic flux density, among the teeth of the stator core installed at a position facing, with a gap, the outer peripheral surface of the rotor core.

11. in the cross section, an angle between a line passing through the rotation axis and a rear corner of the recess, which is a rear corner in the rotation direction of one of two corners at the open end of the recess, and a line passing through the rotation axis and a front corner of the open end, which is located rearward of the recess in the rotation direction at the same pole as the pole at which the recess is installed, is θa; an angle formed by a line passing through a front corner of the recess, which is a front corner in the rotation direction, and the rotation axis, and a line passing through a rear corner of the recess and the rotation axis, is equal to or greater than θa / 8 and equal to or less than 25θa / 24θa, θa is a movement angle (rad) that is an angle around the rotation axis from a rear reference position that is the position of the intersection between a straight line passing through a rear permanent magnet end and the rotation axis and the outer circumferential surface of the rotor core in the cross section, The rear-side permanent magnet end portion is an end portion located at the rearmost side in the circumferential direction among the ends of the permanent magnets installed at the same pole, θa is 2π / N slot It is calculated as N slot The rotor core according to claim 10 , wherein m is the number of slots of a stator core disposed at a position facing the outer circumferential surface of the rotor core with a gap therebetween.

12. 12. The rotor core according to claim 10, wherein a maximum value of a depth of the recess is within a range of 0.01 to 0.1 times a diameter of the rotor core.

13. The rotor core has a plurality of magnet holes per pole, the plurality of magnet holes include a front side magnet hole located on a front side in the rotation direction and a rear side magnet hole located on a rear side in the rotation direction, a space that serves as the front-side flux barrier of the front-side magnet hole is located forward in the rotation direction of a space that serves as the rear-side flux barrier of the front-side magnet hole, a space that serves as the front-side flux barrier and that is included in the rear-side magnet hole is located forward in the rotation direction of a space that serves as the rear-side flux barrier and that is included in the rear-side magnet hole, the soft magnetic material portion has an inter-magnet bridge portion disposed in a region between a space of the front side magnet hole that serves as the rear side flux barrier and a space of the rear side magnet hole that serves as the front side flux barrier, the front magnet hole has a first end portion that is the open end portion on a front side in the rotation direction with respect to the permanent magnet installed in the front magnet hole, the front magnet hole has a second end on a rear side in the rotation direction with respect to the permanent magnet installed in the front magnet hole, the rear-side magnet hole has a first end portion that is the open end portion on the rear side in the rotation direction with respect to the permanent magnet installed in the rear-side magnet hole, the rear magnet hole has a second end on a forward side in the rotation direction with respect to the permanent magnet installed in the rear magnet hole, 3. The rotor core according to claim 1, wherein the second ends of the front magnet holes and the rear magnet holes coincide with ends of spaces that serve as flux barriers and are closed.

14. In the cross section, a length of a portion of the bridge-width defining line that overlaps with the soft magnetic material is 0.02 times or less a diameter of the rotor core, The rotor core according to claim 13 , wherein the bridge width defining line is a straight line connecting the second ends of the front side magnet hole and the rear side magnet hole so as to minimize a length of overlap with the soft magnetic material.

15. In the cross section, each of the front side magnet hole and the rear side magnet hole further has a third end portion located on the outer periphery side in the magnetization direction of the permanent magnet installed in the front side magnet hole and the rear side magnet hole, and a fourth end portion located on the inner periphery side of the third end portion in the magnetization direction of the permanent magnet, In the cross section, the length of the bridge width defining line overlapping with the soft magnetic material is w min Exceeding the bridge width defining line is a straight line connecting the second ends of the front side magnet hole and the rear side magnet hole to each other so as to minimize the length of overlap with the soft magnetic material, W min is ρ × S × r g ×ω÷Ys, ρ is the density of the soft magnetic material (kg / m 3 ) and Ys is the yield stress (Pa) of the soft magnetic material at room temperature, S is the area of ​​the part affected by the external force (m 2 ) and the external force affected portion is a region of the soft magnetic material surrounded in the cross section by the third end of the front-side magnet hole located at one end of the bridge width defining line, the third end of the rear-side magnet hole located at the other end of the bridge width defining line, an outer peripheral surface of the soft magnetic material portion, and the bridge width defining line, r g is the radial distance (m) between the position of the center of gravity of the external force affected part in the cross section and the center of rotation, The rotor core according to claim 13, wherein ω is the angular velocity (rad / sec) of the rotor when rotating at the maximum rotational speed.

16. A rotor core including a soft magnetic portion formed using a soft magnetic material and having at least one magnet hole per pole, The soft magnetic material portion has a recessed portion on an outer circumferential surface, the magnet hole has a first end and a second end in a left-right direction perpendicular to a magnetization direction of a permanent magnet installed in the magnet hole and a direction parallel to a rotation axis that is a center of rotation, At least one of the first end and the second end is an open end, the recessed portion is at a different position from the open end; A rotor core, wherein the recessed portion is located at a position facing, with a gap, a tooth of a stator core other than the tooth having the lowest magnetic flux density, the tooth being installed at a position facing, with a gap, the outer peripheral surface of the rotor core.

17. A rotor core according to claim 1 or 2; A plurality of permanent magnets are disposed in the rotor core; The rotor comprises:

18. 18. The rotor according to claim 17, wherein the permanent magnet has a residual magnetic flux density of 0.8 T or less at room temperature.

19. The rotor of claim 17 , wherein the permanent magnets are rare earth free.

20. A rotor according to claim 17; A stator; A rotating electric machine comprising:

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