Rotary electric machine

Abstract

To provide a high-speed rotary electric machine having a stator structure made of a composite magnetic material, which is capable of reducing AC losses such as eddy current losses in the rotor's permanent magnets.SOLUTION: A rotary electric machine according to the present invention includes a rotor having a permanent magnet 3 and a stator having a stator core 4 made of a magnetic material, the stator is provided with a stator winding 5 for applying a rotating magnetic field to the rotor, and the magnetic material of the stator core 4 is a composite magnetic material in which magnetic powder is dispersed in a matrix material.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a rotating electric machine including a rotor, a stator, and a plurality of permanent magnets arranged in a row along the circumferential direction of a rotor core. [Background technology]

[0002] In recent years, as energy consumption increases, environmental issues such as global warming have attracted international attention, and there is a demand for reducing losses in order to save energy. As electrification advances in various fields, electric motors (hereinafter referred to as "motors"), which are one type of rotating electrical machine, account for 40% of the world's energy consumption. As a means of achieving high output while maintaining the size of the motor, research has been conducted on motors that increase the number of rotations, and one type of ultra-high-speed motor known as an embedded winding synchronous motor has been considered (for example, Non-Patent Document 1).

[0003] In the invention described in Non-Patent Document 1, a structure is considered in which the teeth of the stator core are made of a composite magnetic material, and a magnetic ring made of a composite magnetic material is provided on the side facing the permanent magnet, with the windings embedded in it. The use of a composite magnetic material reduces AC copper loss in the windings, eddy current loss in the permanent magnets, and AC loss due to iron loss in the stator. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Suzuki, Itsuki, Nirei, Masami, Horiuchi, Manabu, Sato, Mitsuhide, Utsubo, Tsuyoshi, Mizuno, Tsutomu, Interior-wound linear synchronous motor for reducing AC losses at ultra-high speed rotation, Journal of the Japan Society of AEM, Vol. 28, No. 2 (2020). Summary of the Invention [Problem to be solved by the invention]

[0005] In the motor described in Non-Patent Document 1, the stator is composed of two materials, a composite magnetic material and an electromagnetic steel sheet, and there is room for improvement in terms of structure and characteristics.

[0006] The present invention has been made in consideration of the above circumstances, and has an object to provide a high-speed rotating electric machine that has a stator core made entirely of composite magnetic material, thereby further reducing AC losses. [Means for solving the problem]

[0007] The rotating electric machine described in claim 1 is a rotating electric machine comprising a rotor having a permanent magnet and a stator having a stator core made of a magnetic material, in which a stator winding is provided on the stator for applying a rotating magnetic field to the rotor, and is characterized in that the magnetic material of the stator core is a composite magnetic material in which magnetic powder is dispersed in a matrix material.

[0008] The rotating electric machine according to a second aspect of the present invention is the rotating electric machine according to the first aspect of the present invention, characterized in that the relative permeability of the composite magnetic material is in the range of 2 or more and less than 20.

[0009] The rotating electric machine described in claim 3 is the one described in claim 1 or 2, and is characterized in that the ratio of the volume of the magnetic powder to the total volume of the magnetic powder and the matrix material is 10 volume % or more and 90 volume % or less.

[0010] The rotating electric machine according to a fourth aspect of the present invention is the rotating electric machine according to the third aspect, characterized in that the magnetic powder is at least one of sendust, iron-based amorphous, and iron silicon.

[0011] The rotating electric machine according to claim 5 is the rotating electric machine according to claim 4, characterized in that the magnetic powder has a particle size of 1 μm or more and 1000 μm or less.

[0012] The rotating electric machine according to claim 6 is the rotating electric machine according to claim 3, characterized in that the matrix material is any one of epoxy, acrylic, urethane, elastomer, phenol, and nylon resins. Effect of the Invention

[0013] The rotating electric machine to which the present invention is applied uses a composite magnetic material as the magnetic material of the stator core, so that the relative permeability of the stator core can be set to 20 or less, and eddy current loss of the rotor's permanent magnet during high-speed rotation can be reduced. In addition, the core loss per unit volume of the stator core is small, so that iron loss of the stator core can be reduced. Furthermore, since the stator core does not have an inner ring, the structure is simple, and coil winding work is easy, just like in a general concentrated winding motor.

[0014] Furthermore, when the relative permeability of the composite magnetic material used in the stator core is 2 or more, the torque constant is improved compared to a coreless motor of the same shape, and DC copper loss during torque action can be reduced. Also, AC copper loss caused by the magnetic flux of the rotor's permanent magnet interlinking with the stator winding (coil) of the stator can be reduced.

[0015] In addition, the magnetic properties of the composite magnetic material used in the stator core can be adjusted by changing the magnetic powder filling rate and type of magnetic powder. Furthermore, when the ratio of the volume of magnetic powder to the total volume of the magnetic powder and matrix material (volume mixing ratio of magnetic powder) is between 10% and 90% by volume, it is possible to achieve high efficiency taking into account the dimensions of the motor and operating characteristics such as rotation speed and torque.

[0016] Furthermore, when the magnetic powder is at least one of sendust, iron-based amorphous, and iron silicon, the material has a small core loss per unit volume, so the efficiency of the rotating electrical machine during high speed rotation can be increased. Furthermore, when the particle size of the magnetic powder is 1 μm or more and 1000 μm or less, the iron loss can be reduced, and the efficiency of the rotating electric machine during high speed rotation can be increased.

[0017] Furthermore, when the matrix material is any of the following resins, such as epoxy, acrylic, urethane, elastomer, phenol, and nylon, insulation properties can be ensured, and the mechanical strength can be easily adjusted by changing the compounding ratio. [Brief description of the drawings]

[0018] [Figure 1]1 is a cross-sectional view of a rotating electric machine to which the present invention is applied, taken along a plane perpendicular to a rotation axis direction. [Diagram 2] 5A to 5C are schematic diagrams for explaining a manufacturing method of a composite magnetic material used in a rotating electric machine to which the present invention is applied. [Diagram 3] 1 is a diagram for explaining the principle of loss reduction and efficiency improvement of a rotating electric machine to which the present invention is applied. [Figure 4] 11 is a cross-sectional view of another rotating electric machine to which the present invention is applied, taken along a plane perpendicular to the direction of the rotating shaft. [Diagram 5] 1 is a graph showing magnetic hysteresis curves of various magnetic materials. [Figure 6] 1 is a graph showing unit volume core loss of various magnetic materials. [Figure 7] 1 is a graph showing a magnetic hysteresis curve of a composite magnetic material (relative permeability μr=2 to 10). [Figure 8] 11 is a cross-sectional view of a rotating electric machine according to Comparative Example 5, cut along a plane perpendicular to the rotation axis direction. FIG. [Figure 9] FIG. 11 is a diagram showing the magnetic flux density distribution in Example 5 and Comparative Examples 1 to 4 by electromagnetic field analysis. [Figure 10] FIG. 11 is a diagram showing the loss density distribution in Example 5 and Comparative Examples 1 to 4 by electromagnetic field analysis. [Figure 11] 1 is a table summarizing the loss analysis results of the motors of Examples 1 to 5 and Comparative Examples 1 to 5 by electromagnetic field analysis (rotation speed: 125,000 rpm). [Figure 12] The results of Figure 11 are shown in a bar graph. [Figure 13] 1 is a bar graph showing the loss analysis results of Example 5 and Comparative Examples 1 to 4 by electromagnetic field analysis (rotation speed: 50,000 rpm). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, the embodiments of the present invention will be described in detail, but the scope of the present invention is not limited to these embodiments. In addition, the same or corresponding reference numerals may be used to designate common parts in each drawing, and the description may be omitted.

[0020] First Embodiment [Structure / Composition] 1 is a partial configuration diagram showing a cross section perpendicular to the rotation axis direction of a rotating electric machine 10 to which the present invention is applied. The rotating electric machine 10 is an electric motor (motor) or a generator.

[0021] The rotating electric machine 10 includes a rotor and a stator. The rotor includes a rotating shaft 1, a rotor core 2, and a plurality of permanent magnets 3 arranged on the outer periphery of the rotor core 2 with alternating polarities. The stator includes a stator core 4 and a stator winding (coil) 5.

[0022] The rotor is arranged concentrically with the stator and has an air gap between it and the stator. The rotor core 2 of the rotor is made of a soft magnetic material and is formed into a cylindrical shape. As an example, the rotor core 2 is formed into a cylindrical shape by laminating a large number of electromagnetic steel plates in the axial direction, which are formed by punching a metal steel plate having high magnetic permeability into an annular shape, which is a so-called laminated steel plate structure.

[0023] The permanent magnets 3 are fixed to the outer peripheral surface of the rotor core 2 so as to face the teeth 42 of the stator core 4 via an air gap. The permanent magnets 3 are magnetized in advance to produce the north and south poles shown in the figure. The magnetization direction of the permanent magnets 3 is the radial direction of the rotor. There are no limitations on the material of the permanent magnets 3, but neodymium magnets or samarium-cobalt magnets are preferred because of their strong magnetic force.

[0024] The stator is formed in an annular shape. The stator is formed of a stator core 4 consisting of an outer ring yoke (hereinafter referred to as "yoke") 41 and a plurality of teeth 42 protruding from the yoke 41 toward the inner periphery, and slots which are spaces between adjacent teeth 42. Stator windings 5 ​​are wound around the teeth 42. The slots are open slots, and the stator core 4 has openings in the slots. The teeth 42 and the permanent magnets 3 do not face each other in the openings. In FIG. 1, as an example, the teeth 42 of the stator of the rotating electric machine are shown to have a six-slot structure with six teeth 42 arranged in the circumferential direction.

[0025] There is no limitation on the winding method of the stator winding 5. For example, concentrated winding or distributed winding can be adopted. However, concentrated winding is preferable from the viewpoint of miniaturization. Examples of materials for the stator winding 5 include copper, aluminum, and superconducting wire, which have low resistivity.

[0026] When the rotating electric machine 10 is a motor, an AC current is passed through the stator windings 5, and the stator generates a rotating magnetic field relative to the rotor. When the rotating electric machine 10 is a generator, the rotation of the rotor's permanent magnets 5 causes magnetic field lines to act on the stator windings 5 ​​of the stator, generating a voltage. There is no limitation on the rotation speed of the rotating electric machine 10, but as an example, a rotation speed of 50,000 rpm or more is preferable, and from the viewpoint of high speed rotation, a rotation speed of 100,000 rpm or more is more preferable.

[0027] [Materials and characteristics of stator core] The stator core 4 (the yoke 41 and the teeth 42) is a magnetic body made of a magnetic material having a relative magnetic permeability exceeding 1. From the viewpoint of reducing AC loss, the relative magnetic permeability of the stator core 4 is preferably 2 to 20, more preferably 2 to 10, for an AC magnetic field having a frequency of, for example, 4 kHz during rotation. The material (magnetic material) of the stator core 4 is not limited as long as it has a relative magnetic permeability in the above range, but a composite magnetic material is preferable from the viewpoint of ease of molding. The magnitude of the magnetic permeability in the composite magnetic material can be controlled by changing the type, shape, and size of the magnetic powder described later, and the mixture ratio of the magnetic powder to the matrix material. The stator core 4 may be made of multiple types of composite magnetic materials having different characteristics in at least one of the magnetic permeability. For example, the stator core may be divided and made of multiple types of composite magnetic materials according to the needs of the characteristics of the rotating electric machine.

[0028] A composite magnetic material is a mixture in which magnetic powder is dispersed in a matrix material. It may be made by mixing magnetic powder with a binder made of resin and solidifying it, or, for example, by mixing magnetic powder with resin and a diluent, stirring, pouring, and then heat-curing it. Composite magnetic materials are characterized by low loss at high frequencies, low magnetic permeability, and high saturation magnetic flux density.

[0029] The magnetic powder is a soft magnetic material formed into a powder (fine particle). Examples of the material of the magnetic powder include iron-based amorphous, sendust, permalloy, iron silicon, NANOMET (registered trademark), and nanocrystalline alloy. The magnetic powder is preferably at least one of these magnetic powders. The magnetic powder is preferably a material that has low iron loss and is easily mixed with resin. In particular, sendust, which has low iron loss, is preferable, and multiple types of magnetic powder may be blended. The magnetic powder may be insulating-coated.

[0030] The shape of the magnetic powder is arbitrary. For example, a mixture of one or more types of powder selected from spherical, chunky, and flat powders can be used as the magnetic powder. Also, a mixture of powders of different shapes and sizes can be used as the magnetic powder. There is no limitation on the shape of the magnetic powder, but a spherical shape is preferable. This is because flat magnetic powder may be oriented by a strong magnetic field, resulting in saturation of the magnetic flux density. There is no limitation on the size of the magnetic powder, but as an example, the particle size of the magnetic powder is preferably 1 μm or more and 1000 μm or less. This is because a smaller size can reduce iron loss.

[0031] The matrix material is a base material in the composite magnetic material, and is a non-magnetic and insulating material. There is no particular limitation as long as the material is hardened from a slurry state, but it is preferable that the material is a resin in terms of manufacturability and insulating properties. There is no limitation on the resin material, and for example, a thermosetting resin or a thermoplastic resin can be used. Examples of thermosetting resins include epoxy resin, phenolic resin, urethane resin, and elastomer resin. Epoxy resin is preferably used because of its high dimensional stability, water resistance, chemical resistance, and electrical insulation. Examples of thermoplastic resins include acrylic resin and nylon resin. Therefore, it is desirable that the matrix material be any of the following resins: epoxy, acrylic, urethane, elastomer, phenol, and nylon.

[0032] There is no limitation on the compounding ratio of the magnetic powder and the resin of the matrix material, and it may be appropriately determined according to the desired characteristics. In an insulating resin, when conductive magnetic powders come into contact with each other, iron loss increases, so it is preferable to set a compounding ratio that does not cause much contact between the magnetic powders. As a result of the compounding, the ratio of the volume of the magnetic powder to the total volume of the magnetic powder and the matrix material (volume mixing ratio of the magnetic powder) is preferably 10 volume % or more and 90 volume % or less, for example. If it is lower than this range, the magnetic flux path is not sufficiently controlled, and conversely, if it is higher, the rigidity of the material itself decreases. Furthermore, from this point of view, the volume mixing ratio of the magnetic powder is more preferably 40 volume % or more and 70 volume % or less.

[0033] [Manufacturing method of stator core] FIG. 2 shows an example of a manufacturing method for a composite magnetic material. First, magnetic powder and a slurry (liquid) matrix material (resin material) are prepared. Next, the resin material and magnetic powder are mixed and stirred to uniformly disperse the magnetic powder in the matrix material. When mixing, solvents, additives, binders, etc. may be added as necessary. Next, the matrix material is heated and molded to harden. This forms the yoke and teeth integrally, completing a stator core of the desired shape. At this time, there is no need to perform compression molding at high pressure as with powder magnetic cores.

[0034] The stator core may be made of multiple types of composite magnetic materials having different magnetic permeabilities. For example, the stator core may be divided and made of multiple types of composite magnetic materials depending on the characteristics of the rotating electric machine.

[0035] [Principles of loss reduction and efficiency improvement] Next, the principle of loss reduction and efficiency improvement of a rotating electrical machine to which the present invention is applied will be described.

[0036] FIG. 3 shows a part of the configuration diagram shown in FIG. 1, and is a schematic diagram for explaining the principle of improving the efficiency of a rotating electric machine. A stator core 4 consisting of a yoke and teeth is formed of a composite magnetic material. The composite magnetic material has a very low relative permeability of 2 to 20. As a result, the rotating electric machine of the present invention can reduce the magnetic resistance difference between the stator slots and teeth, and the difference in magnetic resistance in the direction of rotation is reduced. Furthermore, when the difference in magnetic resistance is reduced, it is effective in suppressing spatial harmonics of the magnetic flux generated in the gap portion, and is effective in reducing iron loss generated in the stator and permanent magnets.

[0037] Meanwhile, coreless motors whose stator core is made of non-magnetic resin also suppress spatial harmonics, but non-magnetic resin has a relative permeability of 1, which means that the magnetic flux of the permanent magnet is easily reduced. As a result, the torque constant is easily reduced, and copper loss is likely to increase when current is passed through the stator winding (coil) to generate torque. Because composite magnetic materials have a higher magnetic permeability than non-magnetic resins, the magnetic flux of the permanent magnet is less likely to decrease, which suppresses the decrease in the torque constant and makes it easier to suppress copper loss when torque is generated.

[0038] In this way, the rotating electrical machine can suppress spatial harmonics by utilizing the low magnetic permeability, and can also suppress copper loss during torque application.

[0039] <Second embodiment> 4 shows a partial configuration diagram (cross-sectional view) of another rotating electric machine to which the present invention is applied, which is shown in a cross section perpendicular to the rotation axis direction. Note that the same components as those already described are given the same reference numerals, and detailed description thereof will be omitted.

[0040] 4, in the rotating electric machine, a composite magnetic material Xa having magnetic properties different from those of the composite magnetic material X of the first embodiment is formed into an annular shape to form a second yoke 44 on the outer periphery of the stator core. For example, the composite magnetic material Xa of the second yoke 44 has a higher magnetic permeability than the composite magnetic material of the stator core 4. Other configurations of the rotating electric machine are similar to those of the rotating electric machine described in the first embodiment.

[0041] As shown in the figure, the composite magnetic material Xa of the second yoke 44 is arranged in an area of ​​about 60% of the outer periphery of the stator core 4, and the composite magnetic material X with different magnetic properties is arranged in an area of ​​about 40% of the center of the rotor (corresponding to the yoke of the stator core 4). The two composite magnetic materials are filled with adhesive or the like without any gaps. By changing the arrangement ratio of the two composite magnetic materials, it is possible to adjust the characteristics of the rotating electric machine, such as magnetic properties, torque properties, efficiency properties, and thermal properties. The composite magnetic material Xa is manufactured in the same manner as the composite magnetic material of the first embodiment, and it is desirable that the relative magnetic permeability is higher than that of the composite magnetic material X.

[0042] The composite magnetic material Xa has a higher magnetic permeability than the composite magnetic material X. In other words, when a part of the stator core is made of the composite magnetic material Xa, the magnetic flux of the permanent magnet is less likely to decrease, the decrease in the torque constant can be suppressed, and the copper loss is less likely to increase when torque is generated than in the first embodiment. The relative magnetic permeability of the composite magnetic material Xa is preferably, for example, 10 to 100, and more preferably 10 to 20.

[0043] Although the embodiment of the present invention has been described above, the rotating electric machine according to the present embodiment may be a motor or a generator as long as the rotor is equipped with a permanent magnet. Also, the above embodiment has been described with reference to a radial gap type rotating electric machine as an example, but the present invention may be applied to an axial gap type rotating electric machine. EXAMPLES

[0044] [Magnetic materials and magnetic properties] The magnetic properties of the composite magnetic material used in the stator core were measured. The magnetic powder was spherical Sendust (FeSiAl alloy) powder (average particle size: 20 μm), and the resin was epoxy resin, which was heated and pressed to harden to produce the composite magnetic material. The magnetic powder mixing ratio was 69 volume %. The manufacturing method was as explained in Figure 2. For comparison, the magnetic properties of electromagnetic steel sheet A (Nippon Steel Corporation: 35H300), electromagnetic steel sheet B (JFE Steel Corporation: 10JNHF600), and iron-based amorphous alloy (METGLAS 2605SA1) were also measured.

[0045] Figure 5 shows the magnetic hysteresis curves of the composite magnetic material, electromagnetic steel sheet A, electromagnetic steel sheet B, and the iron-based amorphous alloy. The horizontal axis is the magnetic field, and the vertical axis is the magnetic flux density. The relative permeability (μr) of the composite magnetic material was 16, while the relative permeability (μr) of electromagnetic steel sheet A, electromagnetic steel sheet B, and the iron-based amorphous alloy was several thousand.

[0046] Figure 6 shows the core loss per unit volume for the composite magnetic material, electromagnetic steel sheet A, electromagnetic steel sheet B, and the iron-based amorphous alloy. The horizontal axis is magnetic flux density, and the vertical axis is iron loss. The iron loss of electromagnetic steel sheet A was the largest, while the iron loss of the composite magnetic material was the smallest. This result shows that the composite magnetic material can be used preferably.

[0047] [Simulation using electromagnetic field analysis] For Examples 1 to 5, a simulation was performed by electromagnetic field analysis on the radial gap type motor model shown in FIG. 1. The simulation was performed for magnetic flux density distribution, loss density distribution, and loss. In Example 5, the above-mentioned Sendust was applied to the magnetic powder as the composite magnetic material, and the simulation was performed using the measured magnetic properties (relative magnetic permeability μr=16). Furthermore, for Examples 1 to 4, the magnetic hysteresis curve shown in FIG. 7 was assumed as the magnetic properties of the composite magnetic material, and the simulation was performed with the relative magnetic permeability set to μr=2 for Example 1, μr=5 for Example 2, μr=7 for Example 3, and μr=10 for Example 4.

[0048] Similar simulations were also performed for comparative examples 1 to 4, using a motor model in which the stator core 4 (yoke 41 and teeth 42) in the motor model shown in Fig. 1 was not made of a composite magnetic material. Comparative example 1 is a case in which the stator core is made of a non-magnetic material (coreless motor), comparative example 2 is a case in which the stator core is made of the iron-based amorphous alloy shown in Figs. 5 and 6, comparative example 3 is a case in which the stator core is made of electromagnetic steel plate B shown in Figs. 5 and 6, and comparative example 4 is a case in which the stator core is made of electromagnetic steel plate A.

[0049] Furthermore, as Comparative Example 5, a simulation by electromagnetic field analysis was performed on a radial gap type motor model shown in Fig. 8. In the motor shown in Fig. 8, in addition to the yoke 41 and teeth 42, the stator core 4 is provided with a magnetic ring 43 on the inner side (toward the center of the rotor) of the teeth 42 that faces the permanent magnets 3. The yoke 41 is made of the aforementioned electromagnetic steel plate A, and the teeth 42 and ring 43 are made of a composite magnetic material (relative permeability μr=16).

[0050] JMAG-Designer (x64) Ver.19.1 was used as the electromagnetic field analysis software. Details of the calculation conditions and material conditions are shown in Tables 1 and 2, respectively. Table 3 shows the shapes and dimensions of each part of Examples 1 to 5 and Comparative Examples 1 to 5. Table 4 shows the specifications of the stator cores and stator windings of the stators of Examples 1 to 5 and Comparative Examples 1 to 5.

[0051] [Table 1]

[0052] [Table 2]

[0053] [Table 3]

[0054] [Table 4]

[0055] [Motor magnetic flux density distribution] FIG. 9 shows the magnetic flux density distribution. FIG. 9(a) shows the magnetic flux density distribution of Comparative Example 4 (electromagnetic steel plate A), FIG. 9(b) shows the magnetic flux density distribution of Comparative Example 3 (electromagnetic steel plate B), FIG. 9(c) shows the magnetic flux density distribution of Comparative Example 2 (iron-based amorphous alloy), FIG. 9(d) shows the magnetic flux density distribution of Comparative Example 1 (coreless motor), and FIG. 9(e) shows the magnetic flux density distribution of Example 5 (composite magnetic material, relative magnetic permeability μr=16). Compared to FIG. 9(a) and FIG. 9(b), the composite magnetic material of FIG. 9(e) has a lower magnetic flux density passing through the stator core, so it is more effective in reducing iron loss than these. In addition, the composite magnetic material of FIG. 9(d) has a higher magnetic flux density of the stator core than the non-magnetic material, so it is more effective in reducing copper loss. The analysis conditions at this time are output 500W, torque 38.2mNm, and rotation speed 125,000rpm.

[0056] In the motor shown in Fig. 1, there are four permanent magnets, and there are two pairs of N and S poles facing the stator core, so the frequency of change in magnetic flux of the permanent magnets is: 2 × 125,000 ÷ 60 ≒ 4167 Hz It is.

[0057] [Motor loss density distribution] The loss density distribution is shown in Figure 10. Figure 10(a) shows the loss density distribution of Comparative Example 4 (electromagnetic steel plate A), Figure 10(b) shows the loss density distribution of Comparative Example 3 (electromagnetic steel plate B), Figure 10(c) shows the loss density distribution of Comparative Example 2 (iron-based amorphous alloy), Figure 10(d) shows the loss density distribution of Comparative Example 1 (coreless motor), and Figure 10(e) shows the loss density distribution of Example 5 (composite magnetic material, relative magnetic permeability μr = 16). Compared to electromagnetic steel plate A, electromagnetic steel plate B, and iron-based amorphous alloy, the loss density of the permanent magnets of the non-magnetic material and composite magnetic material is significantly reduced. Also, the stator iron loss of electromagnetic steel plate A is larger than the others. The analysis conditions are output 500W, torque 38.2mNm, and rotation speed 125,000rpm.

[0058] On the other hand, in the same figure (d), Comparative Example 1 (non-magnetic material) has a higher loss density in the winding portion than Example 5 (composite magnetic material). This is due to an increase in DC copper loss due to a decrease in the torque constant and an increase in AC copper loss due to the magnetic flux of the permanent magnet interlinking with the winding. The analysis conditions are output 500W, torque 38.2mNm, and rotation speed 125,000rpm. [Motor loss analysis]

[0059] 11 and 12 show the results of loss analysis of the motors of Examples 1 to 5 and Comparative Examples 1 to 5. In Comparative Example 4 (electromagnetic steel sheet A), iron loss accounts for the majority, decreasing in the order of Comparative Example 3 (electromagnetic steel sheet B) and Comparative Example 2 (iron-based amorphous alloy). The proportion of magnet eddy current loss is also large in these motors. The increase in loss is due to the large unit volume core loss of the stator core and the influence of spatial harmonics in the gap. The analysis conditions are output 500 W, torque 38.2 mNm, and rotation speed 125,000 rpm. Comparative Example 3 (coreless motor) does not generate iron loss because it does not have a stator core, but the proportion of copper loss is large.

[0060] On the other hand, the motors of Examples 1 to 5 (composite magnetic material) have significantly reduced eddy current loss, hysteresis loss, and magnet eddy current loss in the stator core compared to Comparative Example 4 (electromagnetic steel sheet A), Comparative Example 3 (electromagnetic steel sheet B), and Comparative Example 2 (iron-based amorphous alloy). In addition, the proportion of copper loss is smaller than that of Comparative Example 1 (coreless motor). Furthermore, the motors of Examples 1 to 5 (composite magnetic material) have significantly reduced eddy current loss, hysteresis loss, and magnet eddy current loss in the stator core compared to Comparative Example 5 (teeth 42 and ring 43 are composite magnetic material). In Examples 1 to 5, the DC copper loss and AC copper loss both decrease with an increase in relative permeability, but the magnet eddy current loss tends to increase. The loss was minimized when the relative permeability μr was 7. The analysis conditions were an output of 500 W, a torque of 38.2 mNm, and a rotation speed of 125,000 rpm.

[0061] FIG. 13 is a comparison of losses in Example 5 and Comparative Examples 1 to 4 when the rotation speed is lowered and the torque is increased while maintaining the same output. Because the rotation speed is lowered and the torque is increased, the copper loss is increased in all motors compared to the results in FIG. 11, and the ratio of iron loss to magnet eddy current loss is reduced. Comparative Example 1 (coreless motor) has a low torque constant, so a large current needs to be passed to obtain torque, and the copper loss is significantly increased compared to the composite magnetic material. The analysis conditions are output 500W, torque 95.5mNm, and rotation speed 50,000rpm.

[0062] The above simulation results show that the motor using a composite magnetic material (Sendust) with a relative permeability of 2 to 16 had the lowest loss compared to the other motors, and that reducing the relative permeability to 7 reduced losses even further. [Explanation of symbols]

[0063] 1 Shaft 2 Rotor core 3. Permanent magnets 4. Stator Core 41 York 42 Teeth 43 Ring 44 Second York 5 Stator Winding 10 Rotating Electric Machine

Claims

1. A rotating electric machine comprising: a rotor having a permanent magnet; and a stator having a stator core made of a magnetic material, the stator being provided with a stator winding for applying a rotating magnetic field to the rotor, A rotating electric machine, wherein the magnetic material of the stator core is a composite magnetic material in which magnetic powder is dispersed in a matrix material.

2. 2. The rotating electric machine according to claim 1, wherein the relative permeability of the composite magnetic material is in the range of 2 to 20.

3. 3. The rotating electric machine according to claim 1, wherein in the composite magnetic material, a ratio of a volume of the magnetic powder to a total volume of the magnetic powder and the matrix material is 10 volume % or more and 90 volume % or less.

4. 4. The rotating electric machine according to claim 3, wherein the magnetic powder is at least one of sendust, iron-based amorphous, and iron silicon.

5. 5. The rotating electric machine according to claim 4, wherein the magnetic powder has a particle size of 1 μm or more and 1000 μm or less.

6. 4. The rotating electric machine according to claim 3, wherein the matrix material is any one of epoxy, acrylic, urethane, elastomer, phenol, and nylon resins.

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