Three-phase reactor

Abstract

To achieve a three-phase reactor having relatively small variations in magnetic characteristics using no common leg of a different shape.SOLUTION: A three-phase reactor is provided that includes a core and three coils mounted on the core. The core includes four leg portions and a pair of square plate-shaped coupling portions coupling one end portion or the other end portion of the four leg portions. One end of the four leg portions is connected to four corners of one coupling portion, and the other end of the four leg portions is connected to four corners of the other coupling portion. The three coils are respectively mounted on three of the four leg portions.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a three-phase reactor.

Background Art

[0002] Three-phase reactors used for smoothing three-phase alternating current and the like are known. Patent Document 1 describes a three-phase reactor including a core having a common leg and three coil mounting legs arranged at equal intervals around the common leg. A recess is formed in the common leg so as to surround the coil mounting legs. Thereby, the distance between the outer peripheral surface of the coil mounting leg and the outer peripheral surface of the common leg is set to be equal, and variations in magnetic characteristics generated between the three coils are eliminated.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The three-phase reactor described in Patent Document 1 has a demerit that the manufacturing cost of the common leg is relatively high because a deformed common leg is used.

Means for Solving the Problems

[0005] According to an embodiment of the present invention, there is provided a three-phase reactor including a core and three coils mounted on the core, the core having four legs and a pair of angular plate-shaped connecting portions connecting one end or the other end of the four legs, one ends of the four legs being connected to four corners of one connecting portion, the other ends of the four legs being connected to four corners of the other connecting portion, and the three coils being respectively mounted on three of the four legs.

[0006] In the above three-phase reactor, the connecting portion may be a laminated core.

[0007] In the above three-phase reactor, the four legs may be paired, and each pair of legs may be arranged in a non-laminated direction perpendicular to the lamination direction of the laminated core.

Advantages of the Invention

[0008] According to one embodiment of the present invention, a three-phase reactor with relatively little variation in magnetic characteristics is provided without using a deformed common leg.

Brief Description of the Drawings

[0009]

Figure 1

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Figure 10

Modes for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, for the same or corresponding matters, the same or corresponding reference numerals are given, and redundant descriptions are omitted. Also, in each figure, when a plurality of matters with common reference numerals are displayed, the reference numerals are not necessarily attached to all of the plurality of displays, and the attachment of reference numerals may be appropriately omitted for a part of the plurality of displays.

[0011] FIGS. 1 to 4 are, in order, a perspective view, a front view, a sectional view (plan view), and a plan view of a reactor 1 according to an embodiment of the present invention.

[0012] This embodiment is an example of an embodiment in which the present invention is applied to a three-phase AC reactor (three-phase reactor).

[0013] The reactor 1 includes a core 10 (magnetic core) and three coils 20.

[0014] The core 10 has four bar-shaped (for example, cylindrical) legs 12 (12A, 12B, 12C, 12D) and a pair of angular plate-shaped (for example, square flat plate-shaped) connecting portions 11. For the connecting portion 11 and the legs 12, for example, a laminated core obtained by laminating electromagnetic steel sheets such as silicon steel sheets, an amorphous metal core, a dust core, a ferrite core, a metal composite core formed from a resin containing magnetic particles, or the like can be used.

[0015] Since the core 10 of this embodiment is assembled from the connecting portion 11 and the legs 12 having a simple and general shape, it can be manufactured relatively inexpensively.

[0016] The four legs 12 of this embodiment are formed from the same material and have the same shape and structure. Also, the pair of connecting portions 11 of this embodiment are formed from the same material and have the same shape and structure. Note that the present invention is not limited to this configuration, and at least one of the legs 12 (or the connecting portion 11) may be formed from a different material or may have a different shape or structure. However, it is desirable that the difference in magnetic resistance between the four legs 12 be small.

[0017] The connecting part 11 is a yoke (flux return) that connects the four leg parts 12 to form a magnetic circuit. One end of each of the four leg parts 12 is connected to the four corners of one side of one connecting part 11, and the other end is connected to the four corners of one side of the other connecting part 11.

[0018] The three coils 20 (20A, 20B, 20C) are respectively mounted on the three leg parts 12A, 12B, 12C (that is, the leg parts 12A - C are respectively inserted into the hollow parts of the coils 20A - C). The leg part 12D on which no coil 20 is mounted serves as a common leg.

[0019] Note that the core 10 of this embodiment is a gapless core without a magnetic gap. However, for example, a magnetic gap (an air gap or a gap member formed of a non - magnetic material such as resin) may be provided in the middle part of the leg part 12 or between the leg part 12 and the connecting part 11.

[0020] The coil 20 is formed by spirally winding an insulated conductor such as an enameled wire. As the material of the conductor, for example, copper or aluminum is used. The coil 20 is formed by edge - wise winding a rectangular wire, but it may be of another winding method, or may be formed of a round wire or a stranded wire. Also, the coil 2 may be formed of a conductor in the form of a foil or a strip, such as a copper foil coil or a copper bar coil.

[0021] Regarding two embodiments (Embodiment 1, Embodiment 2) and two comparative examples (Comparative Example 1, Comparative Example 2) of the reactor 1 according to this embodiment, simulation calculations of the magnetic flux density distribution and characteristics were performed. Table 1 is a list summarizing the simulation conditions.

[0022]

Table 1

[0023] Figs. 7 and 8 are a cross-sectional view (plan view) and a plan view of the reactor 901 which is a comparative example. The reactor 901 differs from the reactor 1 according to the embodiment of the present invention described above only in the shape of the connecting portion 911 of the core 910, the arrangement of the legs 12A to D, and the arrangement of the coils 20A to C attached to the legs 12A to C. Specifically, the connecting portion 11 of the reactor 1 is substantially square flat plate-shaped, whereas the connecting portion 911 of the reactor 901 is substantially equilateral triangle flat plate-shaped (Fig. 8). Further, the four legs 12A to D of the reactor 1 are connected to the four corners of one surface of the connecting portion 11, whereas the four legs 12A to D of the reactor 901 are connected to the three corners and the center of gravity of one surface of the connecting portion 911 (Fig. 7).

[0024] The reactor 1 according to the embodiment of the present invention and the reactor 901 have the same size of the interval a between adjacent legs 12. However, the area of the connecting portion 11 of the reactor 1 in plan view is smaller than that of the connecting portion 911 of the reactor 901. Therefore, as shown in Table 1, the volume Vc of the core 10 of the reactor 1 (Example) is smaller than that of the core 910 of the reactor 901 (Comparative Example).

[0025] Note that Example 1 and Example 2, and Comparative Example 1 and Comparative Example 2 differ only in the structure of the connecting portion 11. Example 1 and Comparative Example 1 are simulation models corresponding to those using a laminated core having a laminated structure (specifically, a laminated steel plate obtained by laminating non-oriented silicon steel sheets) for the connecting portion 11. On the other hand, Example 2 and Comparative Example 2 are simulation models corresponding to those using a core having no laminated structure (i.e., a non-laminated structure) for the connecting portion 11. Note that a value corresponding to non-oriented silicon steel was set for the magnetic permeability of the non-laminated connecting portion 11 of Example 2 and Comparative Example 2. Also, in each example and each comparative example, a value corresponding to a powder compact core was set for the magnetic permeability of the legs 12.

[0026] In this specification and the drawings, the connecting part 11 (911) and the core 10 (910) of Example 1 (Comparative Example 1) having a laminated structure are denoted as the connecting part 11L (911L) and the core 10L (910L). Further, the connecting part 11 (911) and the core 10 (910) of Example 2 (Comparative Example 2) not having a laminated structure are denoted as the connecting part 11N (911N) and the core 10N (910N).

[0027] In FIG. 4, the laminated structure of the connecting part 11L formed from a laminated steel plate is schematically illustrated by equally spaced parallel thin horizontal lines. The plurality of non-oriented silicon steel plates constituting the connecting part 11 (laminated steel plate) are stacked in a stacking direction LD (vertical direction in FIG. 4) perpendicular to one end face of the connecting part 11L.

[0028] Similarly, in FIG. 8, the laminated structure of the connecting part 911L formed from a laminated steel plate is schematically illustrated by equally spaced parallel thin horizontal lines. The plurality of non-oriented silicon steel plates constituting the connecting part 911L (laminated steel plate) are stacked in a stacking direction LD (vertical direction in FIG. 8) perpendicular to one end face of the connecting part 911L.

[0029] The simulation was performed for the case where a three-phase alternating current with a phase current Ia (average value) of 27 A was input to the reactor 1 (or reactor 901).

[0030] FIGS. 5, 6, 9, and 10 are diagrams showing the simulation results of the magnetic flux density distributions of Example 1 (core 10L), Example 2 (core 10N), Comparative Example 1 (core 910L), and Comparative Example 2 (core 910N) in order. Further, Table 2 shows the simulation results of the characteristics of each example and each comparative example.

[0031]

Table 2

[0032] Simulations were performed for the voltages and inductances (L values) of each coil 20A - C.

[0033] As shown in Table 2, the average value of the L value in Example 1 is larger than that in Comparative Example 1 having the same laminated structure. As described above, since the volume Vc of the core 10 in Example 1 is smaller than that of the core 910 in Comparative Example 1, it can be said that the utilization efficiency of the core in Example 1 is much higher than that in Comparative Example 1. That is, the volume (or mass) of the core required to obtain the same L value can be smaller in Example 1 than in Comparative Example 1. Therefore, it can be said that Example 1 has a more advantageous configuration for miniaturization and weight reduction than Comparative Example 1.

[0034] Even in the case of the non-laminated structure, the L value in Example 2 is slightly larger than that in Comparative Example 2, and it can be said that Example 2 has a more advantageous configuration for miniaturization and weight reduction than Comparative Example 2.

[0035] Also, in Example 1, compared with Comparative Example 1 having the same laminated structure, the variations (standard deviation σ) of the voltage and inductance between the coils 20A to C (that is, between each phase) are significantly reduced, and the non-uniformity of the characteristics between phases is improved.

[0036] In the case of the non-laminated structure, the variations of the voltage and inductance between the coils 20A to C in Example 2 are suppressed as low as those in Comparative Example 2.

[0037] While the reactor 901 of the comparative example has a highly symmetric structure, particularly in the arrangement of the coil 20, the structure of the reactor 1 according to the embodiment of the present invention has low symmetry. Therefore, initially, it was expected that the characteristics of the reactor 1 according to this embodiment would have a considerably low balance between phases. However, contrary to this expectation, the characteristics of each example are equivalent to those of the corresponding (that is, having the same structure of the connecting portion) comparative example, or, when the connecting portion has a laminated structure, the efficiency is significantly higher than that of the comparative example, and the variations of the characteristics between phases are also reduced, which is a surprising result.

[0038] When comparing the magnetic flux density distributions of the laminated cores 10L and 910L (Figs. 5 and 9) with those of the non-laminated cores 10N and 910N (Figs. 6 and 10), a greater bias in the magnetic flux density distribution is observed in the laminated cores 10L and 910L. This is presumably because the connecting parts 11L and 911L with the laminated structure have a low magnetic permeability between the layers (steel plates), making it difficult for magnetic flux to flow across the layers.

[0039] In the laminated cores 10L and 910L, magnetic flux easily flows along the layers (i.e., in the non-laminated direction ND perpendicular to the lamination direction LD). However, in the core 910L of Comparative Example 1 (Fig. 8), no other leg 12 is arranged on the non-laminated direction ND side of the leg 12B. Therefore, the magnetic flux flowing into the connecting part 911L from the leg 12B cannot reach the other leg 12 without crossing the layer. As a result, the magnetic resistance of the magnetic flux path passing through the leg 12B increases. This is considered to be the reason why the L value of the coil 20B is small in Comparative Example 1, and as a result, the variation in the L value of the reactor 901 increases.

[0040] In the core 10L of Example 1 (Fig. 4), the four legs 12 are paired, and each pair of legs 12 (legs 12A and 12B, legs 12D and 12C) is arranged side by side in the non-laminated direction ND of the connecting part 911L (laminated iron core). Therefore, since other legs 12 are arranged on the non-laminated direction ND side of each leg 12, a magnetic path that does not cross the layer can be formed regardless of which leg 12 is passed through. Therefore, the magnetic resistance of the magnetic flux passing through a specific leg 12 does not increase, and as a result, the L value of Example 1 is considered to be larger and more uniform than that of Comparative Example 1.

[0041] The above is the description of the embodiments of the present invention. However, the present invention is not limited to the configurations of the above embodiments, and various modifications are possible within the scope of the technical idea. For example, embodiments of the present invention also include those obtained by appropriately combining at least a part of the technical configurations of one or more of the embodiments described in the specification with well-known technical configurations.

[0042] In the above-described embodiment, the core 10 has a columnar leg portion 12, but the shape of the leg portion 12 may be a prismatic shape (for example, a regular polygon having a square or a regular pentagon or more as a cross-sectional shape).

Explanation of Signs

[0043] 1 Reactor 10 Core 11 Connecting portion 12 Leg portion 20 Coil 901 Reactor 910 Core 911 Connecting portion

Claims

1. A core, three coils mounted on the core, and comprising, the core being four legs, a pair of angular plate-shaped connecting parts connecting one end or the other end of the four legs, having, one ends of the four legs being connected to four corners of one of the connecting parts, the other ends of the four legs being connected to four corners of the other connecting part, the three coils being respectively mounted on three of the four legs, a three-phase reactor.

2. the connecting part being a laminated core, the three-phase reactor according to Claim 1.

3. the four legs being paired, each pair of the legs being arranged in a non-laminated direction perpendicular to the lamination direction of the laminated core, the three-phase reactor according to Claim 2.

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