Rotating electric machines

Abstract

In an IPM motor (1) according to one aspect of the present invention, in a magnet structure (30) housed in a magnet hole (16), a first soft magnetic body (34A) is located radially outward of a first permanent magnet (32A). Since the first soft magnetic body (34A) has a higher resistivity than the rotor core (14), the generation of eddy current in the first soft magnetic body (34A) can be suppressed. Therefore, in the IPM motor (1), a decrease in efficiency due to eddy current loss can be suppressed, thereby achieving improved efficiency.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Japanese Patent Application No. 2020-29915 filed on February 25, 2020 and Japanese Patent Application No. 2020-206856 filed on December 14, 2020, and the entire contents of which are incorporated herein by reference. Technical Field

[0003] The invention relates to a rotating electric machine. Background Art

[0004] Conventionally, an IPM motor is known as a rotating electrical machine. The IPM motor is a type of inner rotor type motor in which a permanent magnet is embedded inside a rotor (for example, see Patent Document 1 listed below).

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2000-134842

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 11-262205 Summary of the invention

[0008] In the above-mentioned IPM motor, since the coil is wound around the stator in the axial direction of the rotor, a dead space is easily formed near the end of the rotor. Therefore, in order to improve the motor characteristics, it is also considered to set it as follows: the length of the rotor is designed to be longer than the length of the stator, and the rotor end face protrudes from the stator end face. In this structure, it is easy to generate a magnetic flux with a component perpendicular to the rotor end face on the end face of the rotor, and eddy currents are generated on the end face of the rotor due to this magnetic flux change. As a result, the motor efficiency may be reduced due to eddy current loss.

[0009] The inventors have made intensive studies and have recently discovered a technique that can improve the efficiency of a motor by making the end surface of a rotor protrude from the end surface of a stator.

[0010] According to the present invention, a rotating electrical machine capable of achieving improved efficiency is provided.

[0011] A rotating electric machine on one aspect of the present invention comprises a rotor and a stator which can rotate around a predetermined axis, one of the rotor and the stator having a magnet retaining portion for mounting a plurality of magnet structures, and the other having a coil retaining portion for mounting a plurality of coils, wherein each magnet structure is accommodated in each of a plurality of magnet holes extending along the axial direction of the rotor, and has a pair of permanent magnets and soft magnetic bodies, wherein the soft magnetic bodies overlap with the permanent magnets on the radially outer side of the rotor orthogonal to the axial direction.

[0012] In the rotating electric machine, each magnet structure has a soft magnetic body located radially outward from the permanent magnet, which can suppress the generation of eddy current in the soft magnetic body. Therefore, in the rotating electric machine, the reduction in efficiency due to eddy current loss can be suppressed, and the efficiency can be improved.

[0013] In another aspect of the rotating electrical machine, each magnet structure has a plurality of pairs of permanent magnets and soft magnetic bodies.

[0014] In another aspect of the rotating electrical machine, each magnet structure includes a plurality of permanent magnets and a plurality of soft magnetic bodies, and has a stacked structure in which the permanent magnets and the soft magnetic bodies are alternately stacked, and the number of permanent magnets included in the stacked structure is two or three.

[0015] In another aspect of the rotating electrical machine, the innermost layer and the outermost layer of each magnet structure in the radial direction perpendicular to the axial direction of the rotor are formed of a soft magnetic material.

[0016] In another rotating electrical machine, each magnet structure has an arch shape with an inner arc located on the outside in a radial direction perpendicular to the axial direction of the rotor when viewed in the axial direction of the rotor.

[0017] In another rotating electrical machine, the orientation of the permanent magnets of the magnet structure is concentrated toward the outer side in the radial direction perpendicular to the axial direction of the rotor.

[0018] In another rotating electrical machine, each magnet structure has a rectangular shape extending in a radial direction perpendicular to the axial direction of the rotor when viewed in the axial direction of the rotor.

[0019] In another rotating electrical machine, each magnet structure has a V-shape facing outward in a radial direction perpendicular to the axial direction of the rotor when viewed in the axial direction of the rotor.

[0020] In another rotary electric machine, the magnet holding portion is formed of a laminated steel plate obtained by laminating a plurality of silicon steel plates in the axial direction of the rotor, and the soft magnetic body of the magnet structure is formed of a powder compact of soft magnetic powder.

[0021] In the rotating electric machine, the soft magnetic material has a 2.9×10 －4 The resistivity is ~4×10Ω·m and has a saturation magnetic flux density of 1.60~2.10T.

[0022] In another aspect of the rotating electrical machine, the permanent magnet is a sintered magnet. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic plan view showing an IPM motor according to an embodiment.

[0024] Figure 2 yes Figure 1 A cross-sectional view taken along line II-II of the IPM motor shown.

[0025] Figure 3 yes Figure 1 The schematic perspective view of the main parts of the IPM motor shown.

[0026] Figure 4 yes Figure 3 A top view of the main parts of the IPM motor is shown.

[0027] Figure 5 Yes means Figure 3 Diagram of the structure of the magnet structure and magnet orientation shown.

[0028] Figure 6 It is a plan view showing the main parts of an IPM motor of a different type.

[0029] Figure 7 It is a plan view showing the main parts of an IPM motor of a different type.

[0030] Figure 8 It is a plan view showing the main parts of an IPM motor of a different type.

[0031] Fig. 9 It is a plan view showing the main parts of an IPM motor of a different type.

[0032] Fig.10 This is a table showing various conditions of the IPM motor of the embodiment.

[0033] Fig.11 This is a table showing the results of Examples.

[0034] Fig.12 This is a table showing the results of Examples.

[0035] Fig.13 It is a schematic top view showing different types of IPM motors.

[0036] Fig.14 This is a table showing various conditions of the IPM motor of the embodiment.

[0037] Fig.15 This is a table showing the results of Examples.

[0038] Fig.16 It is a graph showing the results of the examples.

[0039] Fig.17 It is a graph showing the results of the examples.

[0040] Fig.18It is a graph showing the results of the examples.

[0041] Fig.19 It is a graph showing the results of the examples.

[0042] Fig. 20 It is a graph showing the results of the examples.

[0043] Fig.21 It is a graph showing the results of the examples.

[0044] Fig. 22 It is a graph showing the results of the examples. DETAILED DESCRIPTION

[0045] Hereinafter, various embodiments and examples will be described with reference to the accompanying drawings. In addition, the same reference numerals are given to the same or corresponding parts in each drawing, and repeated descriptions are omitted.

[0046] In the following embodiment, an electric motor (more specifically, an IPM motor) is used as an example for explanation as a rotating electrical machine. Figure 1 Detailed Description of the Invention An IPM motor 1 according to an embodiment is shown in FIG. Figure 1 1 shows a plan view of the IPM motor 1 as viewed from the direction of the axis X. The IPM motor 1 is an inner rotor type motor having a rotor 10 and a stator 20, and the rotor 10 is located inside the stator 20. The IPM motor 1 has an 8-pole 12-slot structure.

[0047] The rotor 10 includes a shaft 12 and a rotor core 14 (magnet holding portion).

[0048] The shaft 12 has a cylindrical shape and is Figure 1 The shaft 12 is made of, for example, stainless steel.

[0049] The rotor core 14 has a cylindrical shape and has an axial hole 14a inside. The shaft 12 is inserted into the axial hole 14a of the rotor core 14, and the rotor core 14 and the shaft 12 rotate integrally around the axis X. In this embodiment, the outer diameter of the rotor core 14 is 158.4 mm and the inner diameter is 85 mm. In addition, the width W of the rotor core 14 (that is, the length in the direction of the axis X) is 100 mm.

[0050] The rotor core 14 is composed of a plurality of laminated steel plates (electromagnetic steel plates) laminated in the direction of the axis X. The thickness of each steel plate is, for example, 0.2 to 0.5 mm. Silicon steel plates can be used as the steel plates. When the rotor core 14 is composed of laminated steel plates of silicon steel plates, the rotor core 14 has a thickness of 5.6×10 －7 Resistivity of about Ω·m.

[0051] like Figures 1 to 3 As shown, a plurality of magnet structures 30 described later are installed in the rotor core 14. Each magnet structure 30 is accommodated in a magnet hole 16 extending parallel to the axis X of the rotor 10. In more detail, one magnet hole 16 accommodates one magnet structure 30. The inner dimension of the magnet hole 16 is designed to be slightly larger than the outer dimension of the magnet structure 30 described later. Therefore, the position and posture of the magnet structure 30 remain unchanged in the magnet hole 16.

[0052] In the present embodiment, the rotor 10 has eight magnet structures 30 of the same shape, and as for the eight magnet structures 30, pairs of magnet structures 30 are arranged at equal angular intervals on the axis X. When viewed from the direction of the axis X, the magnet structures 30 all have an arched (or C-shaped) end face shape and a cross-sectional shape, and are arranged in a manner such that the inner arc 30a side thereof faces the outer peripheral surface 14b of the rotor core 14. The outer arc 30b of the magnet structure 30 is located on the axis X side of the rotor 10. The opening angle of the magnet structure 30 can be selected from a range of 10 to 180° according to the number of poles of the IPM motor 1, and is 100° in the present embodiment. The magnet structure 30 can be linearly symmetrical with respect to an imaginary line extending along the radial direction of the rotor 10 (a direction passing through the axis X and orthogonal to the axis X). The magnet structures 30 are all radially oriented as a whole, and N-pole magnets 30A having N poles on the inner arc side and S-pole magnets 30B having S poles on the inner arc side are alternately arranged around the axis X.

[0053] The magnet structure 30 is arranged in the magnet hole 16 of the rotor core 14 in such a manner that its extending direction is parallel to the axis X of the rotor 10. Figure 2 As shown, the magnet holes 16 and the magnet structure 30 extend over the entire length of the rotor core 14 in the direction of the axis X. The length of the magnet structure 30 in the extending direction is substantially the same as the width W of the rotor core 14, and is 100 mm in this embodiment.

[0054] The stator 20 includes a cylindrical stator core 21 (coil holding portion) arranged in a manner surrounding the outer circumference of the rotor 10. A gap G of uniform width (0.8 mm width as an example) is provided between the rotor 10 and the stator 20. A plurality of (12 in this embodiment) coils 22 are arranged on the inner circumference of the stator core 21. The plurality of coils 22 are composed of Cu wires of a concentrated winding method and are arranged at equal angular intervals relative to the axis X of the rotor 10. If a three-phase AC voltage is applied to the plurality of coils 22 from an inverter circuit not shown, a rotating magnetic field is generated on the inner circumference of the stator core 21. In this embodiment, the outer diameter of the stator core 21 is 250 mm and the inner diameter is 160 mm. In addition, the width W of the stator core 21 (i.e., the length in the direction of the axis X) is substantially the same as the width W of the rotor core 14, and is 100 mm in this embodiment.

[0055] like Figure 4 and Figure 5 As shown, the magnet structure 30 includes a first permanent magnet 32A and a first soft magnetic body 34A.

[0056] When viewed from the direction of the axis X, the first permanent magnet 32A has an arched (or C-shaped) end face shape and a cross-sectional shape, and its inner arc side faces the outer peripheral surface 14b of the rotor core 14. In other words, the inner arc of the first permanent magnet 32A is located radially outside the rotor 10. In this embodiment, when viewed from the direction of the axis X, the first permanent magnet 32A has a 350 mm 2 area and has a width (radial length) of about 1 to 10 mm.

[0057] The first permanent magnet 32A is a permanent magnet having uniaxial anisotropy. In the present embodiment, the first permanent magnet 32A is composed of a rare earth permanent magnet, such as a neodymium sintered magnet (as an example, a NdFeB sintered magnet). The first permanent magnet 32A may be a sintered magnet other than a neodymium magnet (such as a SmCo sintered magnet or a ferrite sintered magnet), or may be a magnet other than a sintered magnet (such as a bonded magnet or a hot-working magnet, etc.).

[0058] The first permanent magnet 32A is Figure 5 In this way, radial orientation is performed, specifically, concentrated orientation is performed toward the inner curved surface. Compared with the case of being set to parallel orientation, by setting the first permanent magnet 32A to radial orientation, high torque can be easily achieved. The orientation of the first permanent magnet 32A can be a form consistent with the radial orientation angle, and can also be a form in which the orientation is more concentrated on the inner curved surface side compared with the parallel orientation.

[0059] As with the first permanent magnet 32A, when viewed from the direction of the axis X, the first soft magnetic body 34A has an arched (or C-shaped) end face shape and cross-sectional shape, with its inner arc side facing the outer peripheral surface 14b of the rotor core 14. In other words, the inner arc of the first permanent magnet 32A is located radially outward of the rotor 10. In the present embodiment, when viewed from the direction of the axis X, the first soft magnetic body 34A has a width (radial length) of about 0.1 to 30 mm. The first permanent magnet 32A can be composed of one magnet piece or a plurality of magnet pieces as long as it is arched as a whole.

[0060] The first soft magnetic body 34A is made of a soft magnetic material. The first soft magnetic body 34A may be made of an electromagnetic steel plate, magnetic iron powder, soft ferrite, or magnetic alloy. In the present embodiment, the first soft magnetic body 34A is made of a pressed powder body of soft magnetic powder. As the soft magnetic powder of the pressed powder body, Fe 3 Si powder or other pure iron-based magnetic powder. The average particle size (d50) of the soft magnetic powder of the powder compact is, for example, 20 to 100 μm. The powder compact is obtained by bonding the soft magnetic powder, and the bonding can be performed using a binder such as a resin. The powder compact can be obtained by hot forming the soft magnetic powder. 3 When the first soft magnetic body 34A is composed of a pressed powder body of Si powder, the first soft magnetic body 34A has a resistivity of about 300 Ω·m. When the first soft magnetic body 34A is composed of a pressed powder body of soft magnetic powder, the first soft magnetic body 34A has a magnetic permeability of, for example, 500 to 1000 H / m. When the first soft magnetic body 34A is composed of a laminated steel plate, the first soft magnetic body 34A has a magnetic permeability of, for example, 5000 to 20000 H / m (10000 H / m as an example). The first soft magnetic body 34A has a magnetic permeability of 2.9×10 －4 The resistivity is ~4×10Ω·m, and the saturation magnetic flux density is 1.60~2.10T.

[0061] The first soft magnetic body 34A overlaps with the first permanent magnet 32A on the radially outer side of the rotor 10. That is, in the magnet structure 30, the first soft magnetic body 34A is located on the inner arc 30a side, and the first permanent magnet 32A is located on the outer arc 30b side.

[0062] In the process of forming the magnetic structure 30, the first permanent magnet 32A and the first soft magnetic body 34A can be fixed to each other by an adhesive. Alternatively, the magnetic structure 30 can also be obtained by overlapping the powdered body forming the first soft magnetic body 34A and the first permanent magnet 32A and performing resin molding. In this way, the magnetic structure 30 can be accommodated in the magnet hole 16 after forming the magnetic structure 30. Moreover, the sintered magnet can be arranged in the magnet hole 16 in advance, and the mixture of the powdered body and the resin can be injection molded and fixed. Alternatively, the mixture of the powdered body and the resin can be integrated with the permanent magnet by compression molding. The resin used at this time can be a thermoplastic resin such as polyethylene, polypropylene, polyamide, ABS, an epoxy resin or a thermosetting resin of a phenolic resin.

[0063] In the above-mentioned IPM motor 1, the magnet structure 30 accommodated in the magnet hole 16 includes a pair of permanent magnets and a soft magnetic body (i.e., a first permanent magnet 32A and a first soft magnetic body 34A), and the first soft magnetic body 34A is located radially outward of the first permanent magnet 32A. The first soft magnetic body 34A has a resistivity higher than the resistivity of the rotor core 14, so the generation of eddy current in the first soft magnetic body 34A is suppressed. Therefore, in the IPM motor 1, the reduction in efficiency caused by eddy current loss can be suppressed, and the efficiency can be improved.

[0064] In the present embodiment, in addition to a pair of permanent magnets and a soft magnetic body (a first permanent magnet 32A and a first soft magnetic body 34A), a second soft magnetic body 34B is also provided. The second soft magnetic body 34B overlaps with the first permanent magnet 32A on the radial inner side of the rotor 10. That is, in the magnet structure 30, the second soft magnetic body 34B is located on the outer arc 30b side than the first soft magnetic body 34A. That is, the magnet structure 30 has a sandwich structure in which the first permanent magnet 32A is clamped by two soft magnetic bodies 34A and 34B, and the innermost layer (i.e., the first soft magnetic body 34A) and the outermost layer (i.e., the second soft magnetic body 34B) in the radial direction of the rotor 10 are composed of soft magnetic materials. When the magnet structure 30 is arranged in the magnet hole 16, a certain dimensional tolerance is required. However, by forming the innermost and outermost layers of the magnet structure 30 from soft magnetic materials, the soft magnetic material can be processed to obtain the desired outer dimensions, and the magnet structure 30 can be arranged in the magnet hole 16 without reducing the generation of the magnetic force that has a great influence on the torque of the IPM motor 1, that is, without changing the size of the permanent magnet (without reducing the volume of the permanent magnet).

[0065] The magnet structure 30 is integrated by the following method after the permanent magnet is processed into a desired shape. Only the required surface can be processed, or an unprocessed magnet can be used. As for the dimensional tolerance of the magnet structure 30, the processing is performed in a manner that satisfies the soft magnetic body, so the processing of the permanent magnet can be omitted, and the reason is that low cost can be achieved by reducing the processing cost and the grinding cost of the sintered magnet.

[0066] In the IPM motor 1, in addition to the mode in which the magnet structure 30 includes only one pair of permanent magnets and soft magnetic bodies, it is also possible to set the magnet structure 30 to include multiple pairs of permanent magnets and soft magnetic bodies. For example, it is also possible to set the magnet structure 30 to include multiple permanent magnets and multiple soft magnetic bodies, and to have a laminated structure in which permanent magnets and soft magnetic bodies are alternately laminated. In this case, the number of permanent magnets included in the laminated structure can be 2 or 3.

[0067] Figure 6 The figure shows the magnet structure 30 including three pairs of permanent magnets and three pairs of soft magnetic bodies. Figure 6 The magnet structure 30 shown has a laminated structure including three permanent magnets 32A, 32B, 32C and four soft magnetic bodies 34A, 34B, 34C, 34D. The three permanent magnets 32A, 32B, 32C can be made of the same material, and the four soft magnetic bodies 34A, 34B, 34C, 34D can also be made of the same material. The sum of the volumes of the three permanent magnets 32A, 32B, 32C can be substantially equal to Figure 4 The volume of the first permanent magnet 32A shown is the same. With respect to any of the three permanent magnets 32A, 32B, and 32C, since the overlapping soft magnetic bodies 34A, 34B, and 34C are located radially outward (on the outer peripheral surface 14b side of the rotor core 14), the generation of eddy current is suppressed by the higher resistivity of the soft magnetic bodies 34A, 34B, and 34C, as in the above-mentioned IPM motor 1. Figure 6 In the magnet structure 30 shown, the innermost layer and the outermost layer are also made of soft magnetic material, so the outer dimensions can be easily adjusted, and the process of accommodating the magnet structure 30 in the magnet hole 16 can be performed relatively simply.

[0068] Figure 7 The figure shows the magnet structure 30 including six pairs of permanent magnets and soft magnetic bodies. Figure 7 The magnet structure 30 shown has a laminated structure including six permanent magnets 32A to 32F and seven soft magnetic bodies 34A to 34G. The six permanent magnets 32A to 32F can be made of the same material, and the seven soft magnetic bodies 34A to 34G can also be made of the same material. The sum of the volumes of the six permanent magnets 32A to 32F can be substantially equal to Figure 4The volume of the first permanent magnet 32A shown is the same. For any of the six permanent magnets 32A to 32F, since the overlapping soft magnetic bodies 34A to 34G are located radially outward (on the outer peripheral surface 14b side of the rotor core 14), the generation of eddy current is suppressed by the higher resistivity of the soft magnetic bodies 34A to 34G, as in the above-mentioned IPM motor 1. Figure 7 In the magnet structure 30 shown, the innermost layer and the outermost layer are also made of soft magnetic material, so the outer dimensions can be easily adjusted, and the process of accommodating the magnet structure 30 in the magnet hole 16 can be performed relatively simply.

[0069] Figure 6 and Figure 7 The magnet structure 30 shown can be obtained by integrating a plurality of permanent magnets and a plurality of soft magnetic bodies before being accommodated in the magnet hole 16. In this case, compared with the case where a plurality of permanent magnets are accommodated in the magnet hole 16 one by one, it is possible to reduce assembly man-hours or improve manufacturing efficiency.

[0070] In addition, Figure 6 and Figure 7 In the magnet structure 30 shown, since the soft magnetic material exists between the permanent magnets, the d-axis inductance becomes small and the q-axis inductance becomes large, resulting in an increase in the total torque as an IPM motor.

[0071] In the IPM motor 1 , each magnet structure 30 may have a configuration other than the configuration having an arched (or C-shaped) end face shape and a cross-sectional shape, and may have a rectangular or V-shaped end face shape and a cross-sectional shape, for example.

[0072] Figure 8 1 is a diagram showing a magnet structure 30 having a rectangular end face shape and a cross-sectional shape. When viewed from the direction of the axis X, Figure 8 The magnet structure 30 shown has a rectangular end face shape and a cross-sectional shape, and extends in a manner intersecting with the radial direction of the rotor 10. In the present embodiment, it extends in a manner orthogonal to the radial direction of the rotor 10. Therefore, the magnet structure 30 is arranged in a manner such that one long side 30a of the magnet structure 30 faces the outer peripheral surface 14b of the rotor core 14, and the other long side 30b faces the inner peripheral surface 14a of the rotor core 14. Figure 8 The magnet structure 30 shown may be line-symmetrical with respect to an imaginary line extending in the radial direction of the rotor 10 .

[0073] exist Figure 8 The magnet structure 30 shown includes a pair of a first permanent magnet 32A and a first soft magnetic body 34A. When viewed from the direction of the axis X, the first permanent magnet 32A and the first soft magnetic body 34A both have rectangular end faces and cross-sectional shapes. Figure 8 For the magnet structure 30 shown, in addition to the mode of only including one pair of permanent magnets and soft magnetic bodies, it is also possible to set the magnet structure 30 to include multiple pairs of permanent magnets and soft magnetic bodies. For example, the magnet structure 30 can be a mode of only including two pairs of permanent magnets and soft magnetic bodies, or a mode of only including three pairs of permanent magnets and soft magnetic bodies. As long as the first permanent magnet 32A is rectangular as a whole, it can be composed of one magnet piece or a plurality of magnet pieces.

[0074] Fig. 9 1 is a diagram showing a magnet structure 30 having a V-shaped end face shape and a cross-sectional shape. When viewed from the direction of the axis X, Fig. 9 The magnet structure 30 shown has a V-shaped end face shape and cross-sectional shape, and is arranged in such a manner that the inferior angle side faces the outer peripheral surface 14b of the rotor core 14. Therefore, the inferior angle side surface 30a of the magnet structure 30 is opposite to the outer peripheral surface 14b of the rotor core 14, and the superior angle side surface 30b is opposite to the inner peripheral surface 14a of the rotor core 14. Fig. 9 The magnet structure 30 shown may be line-symmetrical with respect to an imaginary line extending in the radial direction of the rotor 10 .

[0075] exist Fig. 9 The magnet structure 30 shown includes a pair of a first permanent magnet 32A and a first soft magnetic body 34A. When viewed from the direction of the axis X, the first permanent magnet 32A and the first soft magnetic body 34A both have a V-shaped end face shape and a cross-sectional shape. Fig. 9 For the magnet structure 30 shown, in addition to the mode of only including one pair of permanent magnets and soft magnetic bodies, it is also possible to set the magnet structure 30 to include multiple pairs of permanent magnets and soft magnetic bodies. For example, the magnet structure 30 can be a mode of only including two pairs of permanent magnets and soft magnetic bodies, or a mode of only including three pairs of permanent magnets and soft magnetic bodies. As long as the first permanent magnet 32A is V-shaped as a whole, it can be composed of one magnet piece or a plurality of magnet pieces.

[0076] Example

[0077] The inventors conducted experiments to confirm Figure 6 and Figure 7 The influence of the multi-layered permanent magnets such as the magnet structure 30 shown in the figure on the motor characteristics is analyzed based on electromagnetic field simulation. The specifications and analysis conditions of the motor of the embodiment are as follows: Fig.10 As shown in the table, the analysis results are as follows Fig.11 and Fig.12 In addition, in all embodiments, the (total) volumes of the permanent magnets in the magnet structure are the same.

[0078] according to Fig.11 It can be seen from the examples 1 to 4 shown that, compared with the case where the number of permanent magnets is one, the maximum torque increases and the torque ripple decreases by setting the number of permanent magnets to a plurality. Fig.11 It can be seen from Examples 2 and 3 that the soft magnetic body composed of an electromagnetic steel sheet and the soft magnetic body composed of a pressed powder molded body of soft magnetic powder have the same maximum torque and torque fluctuation.

[0079] Fig.12 The fifth embodiment shown shows the result when the magnet structure 30 includes only one pair of a permanent magnet and a soft magnetic body, the permanent magnet is parallel-oriented, and the soft magnetic body is composed of an electromagnetic steel sheet. Fig.12 The sixth embodiment shown shows the result when the magnet structure 30 includes three pairs of permanent magnets and soft magnetic bodies, each permanent magnet is made of a bonded magnet (HIDENSE1000), and the soft magnetic body is made of an electromagnetic steel sheet. Fig.12 The embodiment 7 shown shows the result when the magnet structure 30 includes 6 pairs of permanent magnets and soft magnetic bodies, and the soft magnetic body is composed of a pressed powder molded body of soft magnetic powder. According to embodiments 1 to 7, it can be seen that by forming the permanent magnet with sintered magnets, a significant increase in maximum torque can be achieved; compared with parallel orientation, by setting it to radial orientation, an increase in maximum torque and a reduction in torque fluctuation can be achieved. Because there is a resin component in the bonded magnet, the residual magnetic flux density is reduced to 60 to 70% compared with the sintered magnet. In addition, because the bonded magnet needs to eject the magnet component in the magnet hole 16, it is difficult to control the orientation of the magnet component.

[0080] In addition, the inventors Fig.13 The distributed winding IPM motor 1 shown in FIG. 1 was also analyzed in the same manner as in Examples 1 to 7. The specifications and analysis conditions of the motor are as follows: Fig.14 As shown in the table, the analysis results are as follows Fig.15 shown.

[0081] according to Fig.15 It can be seen from the embodiments 8 to 11 shown that in the distributed winding IPM motor, as in the concentrated winding IPM motor, by setting the number of permanent magnets to multiple compared to when the number of permanent magnets is one, the maximum torque is increased and the torque ripple is reduced. Fig.15 It can be seen from Examples 9 and 10 that in the distributed winding IPM motor, the maximum torque and torque fluctuation are the same in the soft magnetic body composed of electromagnetic steel plates and the soft magnetic body composed of pressed powder molded bodies of soft magnetic powder.

[0082] Furthermore, the inventors conducted an analysis to confirm the influence of the shape and number of layers of the permanent magnets of the magnet structure on the motor characteristics. Figure 4The arched permanent magnet shown, Figure 8 The rectangular permanent magnet shown and Fig. 9 For each of the V-shaped permanent magnets shown, the maximum torque when there are 1 layer, 2 layers, 3 layers, and 6 layers is calculated. The analysis results are shown in Tables 1 to 3 and Figure 16 to Figure 18 shown. Fig.16 This is a graph in which the results of Table 1 related to the arch-shaped permanent magnets are plotted. Fig.17 This is a graph in which the results of Table 2 related to rectangular permanent magnets are plotted. Fig.18 This is a graph in which the results of Table 3 related to V-shaped permanent magnets are plotted. Figures 16 to 18 The horizontal axis of the graph is the current phase angle [deg.]. In addition, in the permanent magnets of each shape, the (total) volume of the permanent magnets is the same.

[0083] Table 1

[0084]

[0085] Table 2

[0086]

[0087] Table 3

[0088]

[0089] According to Table 1 to Table 3 and Figure 16 to Figure 18 It can be confirmed that the maximum torque of 2-layer, 3-layer and 6-layer permanent magnets is greater than the maximum torque of 1-layer permanent magnets, or is equivalent to the maximum torque of 1-layer permanent magnets. In particular, it can be confirmed that the maximum torque near the current phase angle of 45° is greater for 2-layer, 3-layer and 6-layer permanent magnets than for 1-layer permanent magnets.

[0090] Fig.19 , Fig. 20 This is a graph showing the relationship between the maximum torque and the number of layers of permanent magnets of various shapes using the results of Tables 1 to 3 above. Fig.19 The vertical axis represents the maximum torque, Fig. 20 The vertical axis represents the ratio of the maximum torque relative to the maximum torque when there is one layer of permanent magnets. Fig.19 , Fig. 20 The curve graph confirms that the maximum torque increases significantly when the number of layers increases from 1 to 2, and that the maximum torque does not increase significantly even when the number of layers increases from 3 to 6. As the number of layers of permanent magnets increases, the manufacturing process and manufacturing cost also increase. Therefore, in order to obtain a large torque while suppressing the manufacturing process and manufacturing cost, the number of layers of permanent magnets can be set to 2 or 3.

[0091] In addition, the inventors conducted an analysis to confirm the influence of the constituent materials of the soft magnetic body of the magnetic structure on the characteristics of the motor. Specifically, for each of the multiple constituent materials (electromagnetic steel plate, pressed powder core A, pressed powder core B, pressed powder core C, ferrite, pressed powder core D), the resistance value, saturation flux density at 80kA / m, torque, eddy current loss of the permanent magnet, and efficiency were confirmed. Tables 4 and 5 are data when the number of layers of the permanent magnet is set to 1 and 3, respectively. Fig.21 This is a graph showing the relationship between the resistance value of the soft magnetic material and the eddy current loss of the permanent magnet using the data in Table 4 and Table 5. Fig. 22 This is a graph showing the relationship between the magnetic flux saturation density and the torque using the data in Tables 4 and 5.

[0092] Table 4

[0093]

[0094] Table 5

[0095]

[0096] According to Table 4, Table 5 and Fig.21 The results show that the eddy current loss of the permanent magnet is large in the soft magnetic body composed of the electromagnetic steel sheet with relatively low resistance value, and the eddy current loss can be suppressed in other constituent materials (compressed powder core A to D, ferrite). On the other hand, according to Table 4, Table 5 and Fig. 22 The results confirm that in the soft magnetic body composed of ferrite, the saturation flux density becomes low, making it difficult to obtain a sufficiently large torque. Based on these results, it can be confirmed that good motor characteristics can be obtained by using a soft magnetic body composed of a pressed powder core. It can also be confirmed that since the soft magnetic body has a 2.9×10 －4 The resistivity is ~4×10Ω·m and the saturation magnetic flux density is 1.60~2.10T, so good motor characteristics can be obtained.

[0097] The rotor of the present invention is not limited to the above-mentioned embodiment, and various modifications are possible.

[0098] For example, in the above-mentioned embodiment, for example, the number of poles or slots of the IPM motor can be appropriately increased or decreased. In addition, the end face shape and cross-sectional shape on the permanent magnet are not limited to the arch shape, and can be a V-shaped shape, etc., or a shape divided into multiple shapes when viewed from the direction of the axis X. In the above-mentioned embodiment, a motor (motor) which is a type of rotating electrical machine is described, but the present invention can also be applied to a generator which is a type of rotating electrical machine.

Claims

1. A rotating electrical machine comprising a rotor and a stator rotatable about a predetermined axis, wherein one of the rotor and the stator has a magnet holding portion on which a plurality of magnet structures are mounted, and the other has a coil holding portion on which a plurality of coils are mounted, Features: Each of the magnet structures is accommodated in each of a plurality of magnet holes extending along the axial direction of the rotor, and comprises a pair of a permanent magnet and a soft magnetic body, wherein the soft magnetic body overlaps with the permanent magnet on the outer side of the radial direction orthogonal to the axial direction of the rotor, The soft magnetic body has a resistivity higher than that of the rotor core. Each of the magnetic structures has a plurality of pairs of the permanent magnets and the soft magnetic bodies, and has a stacked structure in which the permanent magnets and the soft magnetic bodies are alternately stacked.

2. A rotating electric machine comprising a rotor and a stator rotatable about a predetermined axis, wherein one of the rotor and the stator has a magnet holding portion for mounting a plurality of magnet structures, and the other has a coil holding portion for mounting a plurality of coils, Features: Each of the magnet structures is accommodated in each of a plurality of magnet holes extending along the axial direction of the rotor, and comprises a pair of a permanent magnet and a soft magnetic body, wherein the soft magnetic body overlaps with the permanent magnet on the outer side of the radial direction orthogonal to the axial direction of the rotor, The soft magnetic body has a resistivity higher than that of the rotor core. Each of the magnetic structures includes a plurality of the permanent magnets and a plurality of the soft magnetic bodies, and has a stacked structure in which the permanent magnets and the soft magnetic bodies are alternately stacked, and the number of the permanent magnets included in the stacked structure is 2 or 3.

3. The rotating electrical machine according to claim 1 or 2, Features: The innermost layer and the outermost layer of each of the magnet structures in the radial direction orthogonal to the axial direction of the rotor are formed of a soft magnetic material.

4. The rotating electrical machine according to any one of claims 1 to 3, Features: When viewed in the axial direction of the rotor, each of the magnet structures has an arch shape with an inner arc located on the outer side in a radial direction perpendicular to the axial direction of the rotor.

5. The rotating electrical machine according to claim 4, Features: The permanent magnets of the magnet structure are oriented toward the outer side in a radial direction perpendicular to the axial direction of the rotor.

6. The rotating electrical machine according to any one of claims 1 to 3, Features: When viewed in the axial direction of the rotor, each of the magnet structures has a rectangular shape extending in a radial direction perpendicular to the axial direction of the rotor.

7. The rotating electrical machine according to any one of claims 1 to 3, Features: When viewed in the axial direction of the rotor, each of the magnet structures has a V-shape directed outward in a radial direction perpendicular to the axial direction of the rotor.

8. The rotating electrical machine according to any one of claims 1 to 7, Features: The magnet holding portion is formed of a laminated steel plate in which a plurality of silicon steel plates are laminated in the axial direction of the rotor. The soft magnetic body of the magnetic structure is composed of a powder compact of soft magnetic powder.

9. The rotating electrical machine according to any one of claims 1 to 8, Features: The soft magnetic body has a 2.9×10 －4 The resistivity is ~4×10Ω·m and has a saturation magnetic flux density of 1.60~2.10T.

10. The rotating electrical machine according to any one of claims 1 to 9, Features: The permanent magnet is a sintered magnet.

Images