JP2004328871A - High-efficiency rotating machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To offer a high-efficiency rotating machine where a bidirectional eletromagnetic steel plate is applied. <P>SOLUTION: A steel plate, where an average crystal grain diameter is not more than four times and not less than one-tenth the thickness of a board and the area ratio of crystal grains oriented in a cubic azimuth is 75% or over and which contains Si 1% or over and 6.5% or under, is used for a split stator. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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【表２】

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【発明の効果】
以上説明してきたように、本発明にかかる回転機によれば、高い効率での運転が可能となり省エネルギに大きく寄与することができ、その実用上の価値は大きい。また、二方向性珪素鋼板の回転機への用途を拡大したことから、斯界に寄与すること大である。
【図面の簡単な説明】
【図１】図１ａ および図１ｂ は、固定子鉄心の平面形状を、図１ｃは、分割鉄心の構成部材を鋼板から打抜くときの打抜き方向を示すとともに、それらを組み合わせて積層して構成した鉄心を示す略式説明図である。
【図２】図２ａ は、一方向性珪素鋼板の集合組織を、図２ｂ は、二方向性珪素鋼板の集合組織を、そして図２ｃ は、同じく二方向性珪素鋼板の別の例の集合組織をそれぞれ示す模式的説明図である。
【図３】図３ａ および図３ｂ は、実施例における固定子鉄心の配置例を示す模式的説明図である。
【図４】図４ａ は本発明にかかる回転機の、図４ｂ および図４ｃ は、比較例の回転機の結果を示すグラフである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rotating machine such as a generator and a motor, and more particularly to a high-efficiency rotating machine using a bidirectional magnetic steel sheet.
[0002]
[Prior art]
The rotating machine includes a generator, a motor, a linear motor, and the like. Among them, for example, there are various types of motors such as an induction type, a synchronous type using a permanent magnet, and a reluctance torque type.
[0003]
These rotating machines are widely used in modern society so as to consume 50% or more of the total generated power, and it is desired to improve the energy efficiency from the viewpoint of energy saving. For example, the efficiency of a generator greatly affects the energy efficiency of power generation itself.
[0004]
By the way, the most widely used iron core material for such generators, industrial electric rotating machines, and rotating machines in household electric appliances, etc. is a silicon steel sheet containing up to several% of silicon ( Electrical steel sheet). There are two magnetisms required for the silicon steel sheet: low magnetic energy loss in an AC magnetic field and high magnetic flux density in a practical magnetic field. To realize these, it is effective to increase the electric resistance and integrate the <100> axis of the bcc lattice, which is the direction of easy magnetization, in the direction of the magnetic field to be used. In particular, the most effective method for dramatically improving the magnetic characteristics is to integrate the <100> axis, which is the direction of easy magnetization, in the direction of the magnetic field used.
[0005]
Here, a description will be given of a stator core (hereinafter, also simply referred to as an “iron core”) in a rotating machine. FIGS. 1A and 1B show a planar shape of a fixed iron core 14 having a yoke portion 10 and a tooth portion 12. FIG. 1b shows a split stator core 16 and also shows a split core 18 constituting the split stator core. FIG. 1c shows a punching direction when the component member 20 of the split core is punched from the steel plate 22, and also shows an iron core 24 formed by combining and stacking them.
[0006]
What is called a non-oriented electrical steel sheet is an electrical steel sheet having almost no texture, and is preferably used as a core material of a rotating machine. For example, in the case of a stator core of a rotating machine, it is often used by being punched into a shape as shown in FIG.
[0007]
The direction of the magnetic flux in the core of the rotating machine is mainly directed to the circumferential direction and the radial direction of the iron core. Can be punched and laminated in the circumferential direction and used as an iron core. However, the <100> axis, which is the easy magnetization direction, is not oriented in the direction of the magnetic flux in the iron core, and good core magnetization characteristics cannot be expected.
[0008]
On the other hand, a large-sized generator or the like sometimes uses an electromagnetic steel sheet called a unidirectional silicon steel sheet. The <100> axis is oriented in the rolling direction, and in order to orient it in the direction of the magnetic flux, the iron core as shown in FIG. 1b is punched in a circumferentially divided form, and is laminated and used as shown in FIG. 1c. At this time, punching is performed so that the rolling direction, which is the easy magnetization direction, is oriented in the circumferential direction or the radial direction of the iron core. Such an iron core is called a split iron core. The magnetic flux inside the iron core flows mainly in the circumferential direction at the yoke part of the iron core and mainly in the radial direction at the tooth part.Therefore, depending on the design, a core with better characteristics can be obtained compared to using non-oriented electrical steel sheets. Can be However, for example, if a steel sheet is punched with the rolling direction oriented in the direction of the magnetic flux in the yoke, the width direction where magnetization is difficult in the tooth portion coincides with the direction of the magnetic flux, and this is not ideal. In some cases, the rolling direction is aligned with the radial direction of the iron core in order to improve the magnetization characteristics at the teeth, and punching is performed. In this case, however, the magnetic characteristics of the yoke deteriorate. Therefore, such high characteristics cannot be obtained.
[0009]
On the other hand, a steel sheet having a texture in which the {100} plane is parallel to the sheet surface has the largest number of <100> axes in the rolling plane, and is known to be ideal as an iron core of a rotating machine. For example, as shown in FIG. 2b to be described later, a steel sheet having a cubic texture in which <100> axes are accumulated in two directions perpendicular to each other in the plane of the sheet is called a bidirectional silicon steel sheet. As shown in FIG. 1c, it is expected that an iron core having the most excellent characteristics will be obtained by dividing the iron core in the circumferential direction, aligning the easy magnetization direction in the circumferential direction and the radial direction and punching and laminating.
[0010]
Here, FIG. 2 shows the texture of the magnetic steel sheet, FIG. 2A shows a texture called a unidirectional silicon steel sheet, and FIG. 2B shows two textures perpendicular to the rolling direction and the width direction in the sheet surface. It shows a cubic texture in which <100> axes are accumulated in the direction, and this is called a bidirectional silicon steel sheet. FIG. 2c shows the texture of another example of a bidirectional silicon steel sheet. The crystal grains are oriented in two directions at an angle with respect to the axis perpendicular to the rolling direction and the width direction in the plane of the sheet.
[0011]
[Problems to be solved by the invention]
However, although the use of a bidirectional silicon steel sheet as a split core is expected to improve the characteristics of a rotating machine, practically no research has been conducted on a rotating machine using a bidirectional silicon steel sheet as an iron core. . There has been no report of improving the characteristics of a rotating machine using a bidirectional silicon steel sheet as an iron core. Investigations of the present inventors show that when a conventional method of designing a rotating machine is used, even if a bidirectional silicon steel sheet is used for a split-type core, the rotating machine is not improved in efficiency but rather reduced in efficiency. There is even a problem. Therefore, unlike the simplified conceptual idea, even if a bidirectional silicon steel sheet is used for the core of a rotating machine in which the distribution of magnetic flux changes in a complicated manner, the efficiency of the rotating machine can hardly be improved. It was thought that there was no.
[0012]
[Means for Solving the Problems]
In the conventional rotating machine design, the peak value of the cross-sectional average value of the magnetic flux density at the narrowest part of the yoke part of the stator core (hereinafter also referred to as the "yoke part minimum cross-sectional area") (occurs at the maximum output) The peak value of the cross-sectional average value of the magnetic flux density at the central portion of the tooth portion is defined as the saturation magnetic flux density (about 2 to 2 T). .1T) of about 90% (1.8 to 1.9T) or less, because the iron loss portion of the energy loss of the rotating machine consisting of iron loss, copper loss and mechanical loss is excessively large. In general, iron loss increases sharply with high magnetic flux density, and when a rotating machine is operated at high output, the ratio of iron loss to total loss becomes very large. Design has been made.
[0013]
The present inventors have studied the problem of increasing the efficiency of a rotating machine using a bidirectional silicon steel sheet as a split core, and using a bidirectional silicon steel sheet made of fine crystal grains as a material for the split core. Further, they have found that high efficiency can be achieved by operating a rotating machine under a high magnetic flux density, which has not been conventionally performed, and completed the present invention.
[0014]
The reason why the grain must be a bidirectional silicon steel sheet composed of fine crystal grains is that if the crystal grains are large, eddy current loss increases at high speed rotation and iron loss increases. This is because a problem of cracking occurs when it is pulled out.
[0015]
The first reason that the core must be designed with a high magnetic flux density is that the iron loss when a bidirectional silicon steel sheet is assembled into the iron core is different from the conventional prediction, and is negligible when the magnetic flux density is relatively low. This is because iron loss does not decrease or increases in comparison with a grain-oriented silicon steel sheet or the like. This is thought to be caused by the presence of stress due to assembly (tightening) in the core of the rotating machine and the complicated rotation of the magnetic field inside the core. Further, when used at a high magnetic flux density, the iron loss is reduced under the conditions in a practical rotating machine.
[0016]
The second reason is that if a high magnetic flux density design can be performed, the armature portion can be enlarged if the rotating machine has the same size. Thereby, the copper wire diameter can be increased, the electrical resistance can be reduced, and the copper loss can be reduced.
[0017]
The ability to reduce the core volume (cross-sectional area) means not only high efficiency but also downsizing.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
< Magnetic flux density inside iron core, type of rotating machine >
FIG. 3 is a schematic explanatory view showing one arrangement example of the stator core 30 and the rotor 32 in the rotating machine. FIGS. 3A and 3B are different from each other only in the size of the shape of the split core 34. Are substantially the same. In both figures, reference numeral 36 denotes a yoke minimum cross-sectional area portion and a divided surface of the stator core, and reference numeral 36 denotes a tooth portion central cross section. In the rotating machine according to the present invention, any form is not particularly limited as long as the maximum magnetic flux density at the minimum cross-sectional area of the yoke portion of the stator core is 1.75 T or more. The rotating machine in the illustrated example is of a permanent magnet type, and a permanent magnet 40 is embedded in the rotor 32.
[0019]
Yoke magnetic flux density:
In order to reduce iron loss of the iron core and further reduce the core volume, the time maximum value of the cross-sectional average of the magnetic flux density at the minimum cross-sectional area of the yoke portion of the stator core is 1.75 T or more, preferably 1.85 T. Above, more preferably 1.9 T or more.
[0020]
The above time maximum generally occurs when the maximum current is passed through the armature. In the case of the permanent magnet type shown in FIG. 3, specifically, for example, it can be realized by making the yoke portion and / or the tooth portion of the stator core smaller than the conventional one. The same applies to other types of rotating machines. In the case of the permanent magnet type, the magnetic flux density of the permanent magnet may be increased.
[0021]
Tooth magnetic flux density:
In order to reduce iron loss of the iron core and further reduce the core volume, the maximum time of the cross-sectional average of the magnetic flux density at the radial center of the teeth of the stator core (hereinafter also referred to as the "tooth central cross-section") The value is preferably 1.9 T or more, more preferably 1.93 T or more.
[0022]
The above time maximum generally occurs when the maximum current is passed through the armature.
Rotating machine type:
The type of the rotating machine may be any type such as an induction type, a permanent magnet type, a reluctance torque type, a linear type, and a generator. The high-efficiency motor is preferably a brushless synchronous type in which a permanent magnet is arranged on a rotor. A reluctance torque type in which the ratio of iron loss to energy loss is large is also one of the preferred types.
[0023]
< Iron core steel plate >
In order to enable a high magnetic flux density design and obtain a high-efficiency rotating machine, the following bidirectional silicon steel sheet is used at least for the core of the stator. As the material of the rotor core, any magnetic material such as a non-oriented silicon steel sheet or a unidirectional silicon steel sheet may be used. Of course, a bidirectional silicon steel sheet can also be used.
[0024]
The core used in the present invention is a split type, in a punched state as a constituent member of the stator core, a radial direction when the stator core is formed at a circumferential center portion when the stator core is formed, and The area ratio of crystal grains in which the <100> axis of the cubic orientation is oriented within 15 ° from the circumferential direction is 75% or more. It is preferably at least 85%, more preferably at least 90%.
[0025]
[Aggregate organization]
In order to have high magnetic flux density and low iron loss characteristics in two directions perpendicular to the plate surface, the steel plate is developed with a cubic texture. It is preferable from the viewpoint of the punching efficiency of the steel sheet that two directions (<100> axial directions) perpendicular to the sheet surface are the rolling direction and the width direction of the sheet. However, these may be inclined from the rolling direction and the width direction. In short, when the core is formed, it is only necessary to punch through such two directions having high characteristics in the circumferential direction and the radial direction of the core.
[0026]
Therefore, as the texture of the steel sheet, the volume ratio of crystal grains oriented within 15 ° from the cubic orientation is 75% or more, preferably 85% or more, and more preferably 90% or more.
[0027]
Here, “orienting in the“ cubic orientation ”” means that the <100> axis is oriented in two directions orthogonal to each other in the plane of the steel sheet.
[Grain size]
In order to reduce eddy current loss and obtain a low iron loss, to prevent cracking at the time of punching an iron core, the average crystal grain size is four times or less of the plate thickness, and to reduce hysteresis loss and obtain a low iron loss, .1 times or more. Preferably, the average crystal grain size is 3 times or less and 0.3 times or more of the plate thickness. More preferably, it is 2 times or less and 0.5 times or more.
[0028]
[Component composition]
In the case of the present invention, the composition is not particularly limited as long as it is an electromagnetic steel sheet. Therefore, in the present invention, it is only necessary to limit the content of Si to 1 to 6.5%. In this specification, "%" indicating the steel composition is% by mass.
[0029]
Si:
Si is contained in an amount of 1% or more to increase electric resistance and reduce eddy current loss. If it is contained in a large amount, the saturation magnetization is reduced, the material becomes brittle, and the workability is deteriorated. From the viewpoint of magnetic properties and workability, the content is preferably 2% or more and 4% or less.
[0030]
Mn:
Mn may be contained in order to increase electric resistance and reduce eddy current loss. If it is contained in a large amount, the saturation magnetization is reduced.
[0031]
C:
C is preferably at most 30 ppm in order not to cause magnetic aging.
Al:
Al may be contained, for example, in an amount of 0.1% or more to increase electric resistance. If it is contained in a large amount, the magnetostriction increases, so 3% is added as an upper limit.
[0032]
Cr:
Cr may be contained to increase electric resistance. When contained in a large amount, the magnetic flux density decreases, so that the upper limit is preferably 2%.
Other impurities are also in the range allowed for general electromagnetic steel sheets.
[0033]
[Thickness]
In order to reduce eddy current loss and iron loss, a thickness of 0.4 mm or less is preferable. On the other hand, the lower limit of the sheet thickness is not particularly limited as long as it can be manufactured by cold rolling, but is preferably 0.1 mm or more in order to reduce the labor for iron core lamination.
[0034]
[coating]
In order to prevent the generation of macroscopic eddy currents in the iron core, it is preferable to apply a coating for insulation. A conventionally known insulating film such as an organic substance, an inorganic substance, and a mixture thereof can be applied.
[0035]
The present inventors have studied the manufacturing method of the bidirectional silicon steel sheet and found a method of manufacturing a high-performance bidirectional silicon steel sheet composed of fine crystal grains of about 0.5 mm. See JP-A-9-20966 and WO98 / 20179.
[0036]
【Example】
A bidirectional silicon steel sheet having the composition shown in Table 1 was prepared. The plate thickness is 0.36 mm, the average crystal grain size when observed from the surface of the plate by Electron Back Scattering Pattern (EBSP) method is 0.58 mm, and 98% of the crystal grains are 15 ° from the {100} <001> orientation. Had a heading within. The magnetic flux density at 800 A / m in the rolling direction and the sheet width direction was about 1.85 T. From this steel plate, the components of the split core shown in FIG. 3a were stamped. At this time, punching was performed so that the circumferential direction at the circumferential center of the stator core of the component member was the rolling direction. After the punching, strain relief annealing was performed, and an insulating film was further applied. No problems such as cracking of the steel plate due to punching occurred.
[0037]
The constituent members were laminated to form a split iron core, wound with an armature coil, and assembled to produce a synchronous rotating machine. The outer shape and inner diameter of the stator core are 200 mm and 128 mm, respectively, and the stack thickness is about 50 mm.
[0038]
A high-grade non-oriented silicon steel sheet was used for the rotor core. The structure of the rotor is of a magnet embedded type in which a rare earth magnet is embedded as shown in FIG. 3A (8-pole magnet embedded synchronous rotating machine). The armature coils are concentrated winding. After assembling the stator, it was shrink-fitted in a case. The peak value of the cross-sectional average magnetic flux density at the yoke minimum cross-sectional area is 1.95 T, and the peak value of the cross-sectional average magnetic flux density at the central portion of the tooth portion is 1.93 T.
[0039]
As a comparative rotating machine (Comparative Example 1), a rotor made of a commercially available high-grade non-oriented silicon steel sheet (35A300) having a thickness of 0.35 mm was also manufactured. As shown in FIG. 3B, the structure of the stator at this time is designed so that the widths of the yoke portion and the tooth portion are larger by about 20% and 5%, respectively, than those described above. The outer diameter and inner diameter of the stator core are the same as those described above.
[0040]
Therefore, the window around which the armature coil is wound is narrowed. The copper wire of the armature coil was reduced by about 20%. After punching out the steel sheet, it was subjected to strain relief annealing. The insulating coating is originally applied. Other conditions of the armature and the rotor are the same as those described above. The peak value of the cross-sectional average magnetic flux density at the yoke minimum cross-sectional area is 1.55T, and the peak value of the cross-sectional average magnetic flux density at the central section of the tooth portion is 1.85T.
[0041]
Another comparative rotating machine (Comparative Example 2) was produced. The structure of this rotating machine was the same as the structure of the comparative rotating machine 1 described above, and only the material of the stator core was changed to the aforementioned bidirectional silicon steel sheet. After the punching, a strain relief annealing was performed, an insulating film was further applied, the layers were laminated, and a rotating machine was assembled in the same manner as described above. The peak value of the cross-sectional average magnetic flux density at the yoke minimum cross-sectional area is 1.55T, and the peak value of the cross-sectional average magnetic flux density at the central section of the tooth portion is 1.85T.
[0042]
The efficiency characteristics of these rotating machines are shown in Tables 2 to 4 and FIGS.
The rotating machine of the present invention exhibits higher efficiency in the entire rotation speed range than the conventional design using a non-oriented silicon steel sheet (Comparative rotating machine 1). In addition, the efficiency of a rotating machine (comparative rotating machine 2) using a bidirectional silicon steel sheet and having a conventional design is almost the same as or slightly lower than that of the comparative rotating machine 2 using a non-oriented silicon steel sheet. You can see that there is.
[0043]
Thus, the rotating machine of the present invention exhibits excellent characteristics.
[0044]
[Table 1]

[0045]
[Table 2]

[0046]
[Table 3]

[0047]
[Table 4]

[0048]
【The invention's effect】
As described above, according to the rotating machine of the present invention, high-efficiency operation is possible, which can greatly contribute to energy saving, and its practical value is great. Further, since the use of the bidirectional silicon steel sheet for a rotating machine has been expanded, it will greatly contribute to the art.
[Brief description of the drawings]
FIGS. 1a and 1b show a plan shape of a stator core, and FIG. 1c shows a punching direction when punching out constituent members of a split core from a steel plate, and they are combined and laminated. It is a schematic explanatory drawing which shows an iron core.
2a shows the texture of a grain-oriented silicon steel sheet, FIG. 2b shows the texture of a grain-oriented silicon steel sheet, and FIG. 2c shows the texture of another example of a grain-oriented silicon steel sheet. FIG.
FIGS. 3A and 3B are schematic explanatory views showing an example of arrangement of a stator core in the embodiment.
FIG. 4a is a graph showing the result of the rotating machine according to the present invention, and FIGS. 4b and 4c are graphs showing the result of the rotating machine of the comparative example.

Claims (5)

A stator in which a stator core is of a split type, wherein a maximum magnetic flux density in a minimum cross-sectional area of a yoke portion of the stator core is 1.75 T or more, and a split core constituting the stator core has a mass% of Containing 1% or more and 6.5% or less of Si, having an average grain size of 0.1 to 4 times the plate thickness, and being oriented within 15 ° from one cubic orientation A steel sheet having an area ratio of not less than 75%, and a <100> axis of the cubic orientation at the center in the circumferential direction when the stator core of the split iron core is formed. A rotating machine characterized by being oriented in a radial direction and a circumferential direction when configured. The rotating machine according to claim 1, wherein the steel sheet has an area ratio of crystal grains oriented in a {100} <001> direction of 85% or more. 3. The rotating machine according to claim 1, wherein the steel sheet contains 2% or more and 4% or less of Si in mass%, and has a thickness of 0.1 mm or more and 0.4 mm or less. 4. The stator core has a maximum magnetic flux density of 1.85 T or more in a yoke portion minimum cross-sectional area portion, and a maximum magnetic flux density of 1.9 T or more in a central cross-sectional portion of a tooth portion of the stator core. The rotating machine according to any one of claims 1 to 3. The rotating machine according to any one of claims 1 to 4, wherein the rotating machine is of a synchronous type in which a permanent magnet is arranged on a rotor.

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