Three phase ac wire

Abstract

To provide a three phase AC wire in which reduction of inductance is attained.SOLUTION: A three phase AC wire has multiple arc-shaped conductors whose cross-sectional shapes perpendicular to the longitudinal direction are arc-shaped, and the multiple arc-shaped conductors are arranged circumferentially so as to form two concentric circles, which includes inner conductors arranged to form the inner circle of the concentric circles and outer conductors arranged to form the outer circle of the concentric circles. In each of the inner conductors and the outer conductors, the circumferentially adjacent arc-shaped conductors are spaced apart, and the arc-shaped conductors carrying the u-phase, v-phase, and w-phase of a three-phase alternating current are arranged in sequence in the circumferential direction. Each arc-shaped conductor is positioned such that it faces, in the radial direction, two arc-shaped conductors carrying phases different from the phase flowing through the arc-shaped conductor. One of the two conductors carrying the different phases faces one end in the circumferential direction, and the other faces the other end in the circumferential direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a three-phase AC electric wire through which three-phase AC current is passed. [Background technology]

[0002] Conventionally, known AC electric wires include single-phase two-wire electric wires and three-phase three-wire electric wires. In three-phase AC electric wires, current is passed through each phase, referred to as u-phase, v-phase, w-phase, A-phase, B-phase, C-phase, etc., with a phase difference of 120 degrees. Therefore, in three-phase AC, even when transmitting the same power as single-phase AC, the current value flowing through the conductor can be lower than that of single-phase AC, thereby reducing electrical loss. When AC current flows through an electric wire, factors such as inductance, reactance, and impedance are known to affect loss. Patent Document 1 listed below discloses a technique for reducing impedance by dividing the conductors of each phase in a three-phase AC electric wire into multiple strips and arranging them so that the same phase strips are not adjacent to each other. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Publication No. 49-41269 Summary of the Invention [Problem to be solved by the invention]

[0004] Among the factors that affect electrical loss in three-phase AC electric wires, inductance can cause voltage fluctuations, so there is a demand for reducing it. However, to date, no sufficient measures have been established to reduce the inductance in three-phase AC electric wires. Therefore, an object of the present invention is to provide a three-phase AC electric wire with reduced inductance. [Means for solving the problem]

[0005] In order to solve the above problems, the present invention provides: A three-phase AC electric wire through which three-phase AC is passed, a plurality of arc-shaped conductors having a length direction and having an arc-shaped cross section perpendicular to the length direction; The plurality of arc-shaped conductors include: The two concentric circles are arranged side by side in the circumferential direction so as to form two concentric circles on the cross section, an inner conductor arranged to form an inner circle of the concentric circles; an outer conductor arranged to form an outer circle of the concentric circles, In each of the inner conductor and the outer conductor, The arc-shaped conductors adjacent to each other in the circumferential direction are arranged at a distance from each other, The arc-shaped conductors through which the u-phase, v-phase, and w-phase of the three-phase AC flow are arranged in order in the circumferential direction, Each of the arc-shaped conductors has: the arc-shaped conductor is disposed so as to face the arc-shaped conductor in the radial direction, through which two phases different from the phases flowing through the arc-shaped conductor; The arc-shaped conductor faces, at one end side in the circumferential direction, the arc-shaped conductor through which one of two phases different from the phase flowing through the arc-shaped conductor flows, The present invention provides a three-phase AC electric wire that faces, at the other end in the circumferential direction, the arc-shaped conductor through which the other of two phases different from the phase flowing through the arc-shaped conductor flows. [Effects of the Invention]

[0006] According to the present invention, it is possible to reduce the inductance in a three-phase AC electric wire. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic perspective view showing a three-phase AC electric wire according to one embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view showing the structure of a wire body of a three-phase AC wire. [Figure 3] FIG. 3 is a schematic cross-sectional view showing the structure of a wire body of a three-phase AC wire. [Figure 4]FIG. 4 is a partially cutaway schematic perspective view showing the internal structure of the three-phase AC electric wire. [Figure 5a] FIG. 5a is a partially cutaway schematic perspective view showing the internal structure of a three-phase AC electric wire in another embodiment different from that in FIG. [Figure 5b] FIG. 5b is a schematic front view showing the internal structure of a three-phase AC electric wire of another embodiment different from that of FIG. 4, as viewed from a direction perpendicular to the length direction. [Figure 6a] FIG. 6a is an explanatory diagram showing simulation models of the three-phase AC electric wires of Comparative Example 1, Comparative Example 2, and Example. [Figure 6b] FIG. 6b is an explanatory diagram showing the simulation results of the three-phase AC electric wires of Comparative Example 1, Comparative Example 2, and Example. [Figure 7a] FIG. 7a is an explanatory diagram showing a simulation model of the three-phase AC electric wires of Comparative Examples 3 and 4. As shown in FIG. [Figure 7b] FIG. 7b is an explanatory diagram showing the simulation results of the three-phase AC electric wires of Comparative Examples 3 and 4. As shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the present invention will be described below with reference to the drawings. A three-phase AC electric wire 1 shown in FIG. 1 is used to carry AC current of three phases: u-phase, v-phase, and w-phase, which are 120 degrees out of phase with each other. The three-phase AC electric wire 1 of this embodiment includes a wire main body 10 including a conductor and an insulating layer covering the conductor, and a sheath 20 that covers the wire main body 10. The three-phase AC electric wire 1 shown in FIG. 1 is a round wire, and the wire main body 10 has a length direction DL that is parallel to a central axis CAX that extends through the center of the wire main body 10, and a circumferential direction DR that winds around the central axis. The wire main body 10 also has a radial direction DD that is a direction along an imaginary plane VP that is perpendicular to the length direction DL and that passes through the central axis.

[0009] The sheath portion 20 has a cylindrical shape whose inner diameter corresponds to the outer diameter of the wire main body 10, and the outer peripheral surface of the wire main body 10 abuts against the inner peripheral surface thereof to cover the wire main body 10 from the outside in the radial direction DD, thereby constituting the outer surface of the three-phase AC wire 1. The sheath portion 20 of this embodiment has a substantially constant thickness in the circumferential direction DR so that the central axis of the three-phase AC wire 1 and the central axis CAX of the wire main body 10 coincide with each other.

[0010] 2 shows a cross section of the wire body 10 cut along an imaginary plane VP perpendicular to the longitudinal direction DL, as viewed from the front, and as shown in Fig. 1 and Fig. 2, the three-phase AC wire 1 has a plurality of arc-shaped conductors C each having an arc-like shape (a shape that forms part of a circumference) in the cross section. In this embodiment, the plurality of arc-shaped conductors C are arranged side by side in the circumferential direction DR so as to describe two concentric circles in the cross section, and include an inner conductor CI arranged to form the inner circle of the concentric circles and an outer conductor CO arranged to form the outer circle of the concentric circles.

[0011] The inner conductor CI of this embodiment is composed of three arc-shaped conductors C, namely, a first inner conductor CI1, a second inner conductor CI2, and a third inner conductor CI3, such that the circumference is divided into three parts. In the inner conductor CI, the first inner conductor CI1, the second inner conductor CI2, and the third inner conductor CI3 are arranged in order in a clockwise direction in the cross section. The total length of the three arc-shaped conductors C, namely, the first inner conductor CI1, the second inner conductor CI2, and the third inner conductor CI3, in the circumferential direction DR is shorter than the circumferential length of the circumference passing through the inner conductor CI, and it is preferable that the length of each of the first inner conductor CI1, the second inner conductor CI2, and the third inner conductor CI3 in the circumferential direction DR is shorter than one-third of the circumferential length of the circumference.

[0012] In this embodiment, the outer conductor CO is composed of three arc-shaped conductors C so that the circumference is divided into three, similar to the inner conductor CI. The outer conductor CO is composed of three arc-shaped conductors C: a first outer conductor CO1, a second outer conductor CO2, and a third outer conductor CO3. In the outer conductor CO, the first outer conductor CO1, the second outer conductor CO2, and the third outer conductor CO3 are arranged in order in a clockwise direction in the cross section. The total length of the first outer conductor CO1, the second outer conductor CO2, and the third outer conductor CO3 in the circumferential direction DR is shorter than the circumferential length of the circumference passing through the outer conductor CO, and it is preferable that the length of each of the first outer conductor CO1, the second outer conductor CO2, and the third outer conductor CO3 in the circumferential direction DR is shorter than one-third of the circumferential length of the circumference.

[0013] The three-phase AC electric wire 1 of this embodiment has an inner conductor C1 composed of three arc-shaped conductors C, and an outer conductor CO composed of three arc-shaped conductors C, for a total of six arc-shaped conductors C. AC currents of three phases, u-phase, v-phase, and w-phase, are each branched into two, one on the inner conductor C1 side and the other on the outer conductor CO side, and then passed through them. The three-phase AC electric wire 1 of this embodiment is used such that the inner and outer arc-shaped conductors C are connected at their terminals, and the same phases are electrically connected together.

[0014] In the wire main body 10 of this embodiment, one of the arc-shaped conductors C constituting the inner conductor CI is arranged to face two of the arc-shaped conductors C constituting the outer conductor CO on the outer side in the radial direction DD, and one of the arc-shaped conductors C constituting the outer conductor CO is arranged to face two of the arc-shaped conductors C constituting the inner conductor CI on the inner side in the radial direction DD. That is, in a portion of the wire main body 10 of this embodiment where the inner conductor CI or the outer conductor CO is divided, one of the inner conductors CI and two of the outer conductors CO face each other, or one of the outer conductors CO and two of the inner conductors CI face each other, and three arc-shaped conductors C face each other in the radial direction DD.

[0015] In the three-phase AC electric wire 1 of this embodiment, AC currents of different phases are passed through three conductors facing each other in the radial direction DD in the electric wire main body 10. In the electric wire main body 10 of this embodiment, AC currents of different phases are passed through the first inner conductor CI1, the second inner conductor CI2, and the third inner conductor CI3 that constitute the inner conductor CI, and AC currents of different phases are passed through the first outer conductor CO1, the second outer conductor CO2, and the third outer conductor CO3, respectively. That is, in the three-phase AC electric wire 1 of this embodiment, a first arc-shaped conductor C (e.g., the first inner conductor CI1 or the first outer conductor CO1), through which an AC current of one of the three phases, u, v, and w, flows, is adjacent to a second arc-shaped conductor C (e.g., the second inner conductor CI2 or the second outer conductor CO2), through which one of the two phases other than the phase through which the first arc-shaped conductor C flows, and a third arc-shaped conductor C (e.g., the third inner conductor CI3 or the third outer conductor CO3), through which the other phase flows, in the circumferential direction DR and also face each other in the radial direction DD.

[0016] When two conductors are arranged side by side and AC currents of different phases are passed through each conductor, an induced potential or the like is generated in one conductor due to changes in the electric field and magnetic field of the other conductor, which can cause an increase in inductance. In the three-phase AC electric wire 1 of this embodiment, the arc-shaped conductors C are arranged as described above, which balances the effects of the electric field and magnetic field and suppresses an increase in inductance, thereby reducing inductance compared to conventional three-phase AC electric wires. Therefore, in the three-phase AC electric wire 1 of this embodiment, it is preferable that the arc-shaped conductors C are arranged so as to have at least a certain degree of symmetry.

[0017] The inner conductor CI and the outer conductor CO are arranged in two mirror-symmetric cross sections obtained by cutting the wire main body 10 along an imaginary plane VP perpendicular to the longitudinal direction DL. In one of the cross sections, the arc-shaped conductors C through which the u-phase flows (e.g., the first inner conductor CI1 and the first outer conductor CO1), the arc-shaped conductors C through which the v-phase flows (e.g., the second inner conductor CI2 and the second outer conductor CO2), and the arc-shaped conductors C through which the w-phase flows (e.g., the third inner conductor CI3 and the third outer conductor CO3) are arranged in clockwise order, while in the other cross section, they are arranged counterclockwise.

[0018] In this embodiment, a first insulating layer S1 is interposed between the inner conductor CI and the outer conductor CO to ensure electrical insulation between them. The wire body 10 of this embodiment also includes a second insulating layer S2 between the outer conductor CO and the sheath 20, and the outer surface of the second insulating layer S2 forms the outer surface of the wire body 10. The wire body 10 of this embodiment also includes a round-bar-shaped insulating core S0 that supports the inner conductor CI from the inside in the radial direction DD. The three-phase AC wire 1 of this embodiment may be configured so that the outer conductor CO is in direct contact with the sheath 20 without including the second insulating layer S2. When the second insulating layer S2 is provided, the three-phase AC wire 1 may be configured only with the wire body 10 without including the sheath 20. In addition, although the figure illustrates a three-phase AC electric wire 1 having an insulating core S0, the insulating core S0 may be simply left as a space to provide a cylindrical electric wire main body 10, with the inner conductor CI exposed on the inner peripheral surface.

[0019] In the wire main body 10 of this embodiment, a predetermined distance is provided between the inner conductor CI and the outer conductor CO that face each other in the radial direction DD to ensure electrical insulation, and a predetermined distance is also provided between adjacent arc-shaped conductors C in the circumferential direction DR to ensure electrical insulation. In the wire main body 10 of this embodiment, alternating currents of different phases are passed through the arc-shaped conductors C that are adjacent in the circumferential direction DR, so an insulating section G is provided between them to ensure electrical insulation.

[0020] As described above, the inner conductor CI and outer conductor CO in this embodiment are configured so that the circumference is divided into three parts, and three insulating sections G (hereinafter also referred to as "inner insulating sections GI") are provided between the arc-shaped conductors C that make up the inner conductor CI, and three insulating sections G (hereinafter also referred to as "outer insulating sections GO") are provided between the arc-shaped conductors C that make up the outer conductor CO.

[0021] The inner insulating sections GI, which are arranged adjacent to the arc-shaped conductor C constituting the inner conductor CI in the circumferential direction DR, include an inner first insulating section GI1 arranged between the first inner conductor CI1 and the second inner conductor CI2, an inner second insulating section GI2 arranged between the second inner conductor CI2 and the third inner conductor CI3, and an inner third insulating section GI3 arranged between the third inner conductor CI3 and the first inner conductor CI1.

[0022] The outer insulating section GO, which is arranged adjacent to the arc-shaped conductor C constituting the outer conductor CO in the circumferential direction DR, includes an outer first insulating section GO1 arranged between the first outer conductor CO1 and the second outer conductor CO2, an outer second insulating section GO2 arranged between the second outer conductor CO2 and the third outer conductor CO3, and an outer third insulating section GO3 arranged between the third outer conductor CO3 and the first outer conductor CO1.

[0023] Although the three-phase AC electric wire 1 of this embodiment can be used to pass high-voltage AC (more than 600 V but not more than 7 kV), it is primarily used for passing low-voltage AC (not more than 600 V). The three-phase AC electric wire 1 of this embodiment may be used to pass AC current at commercial frequencies (50 Hz, 60 Hz) or high-frequency three-phase AC. The insulation section G can be appropriately changed depending on how the three-phase AC electric wire 1 is used. For example, the length of the shortest distance between the edges of adjacent arc-shaped conductors C (linear distance in the cross section) may be 0.5 mm or more. The distance between the edges of the arc-shaped conductors C may be 0.8 mm or more, or may be 1.0 mm or more. The distance between the edges of the arc-shaped conductors C is, for example, 20 mm or less. The distance between the edges of the arc-shaped conductors C may be 16 mm or less, or may be 12 mm or less.

[0024] In the cross section of the wire main body 10 of this embodiment, the intervals (θgi) occupied by each inner insulated section GI while making a full turn 360 degrees around the central axis CAX along the inner conductor CI and the intervals (θgo) occupied by each outer insulated section GO while making a full turn along the outer conductor CO may be, for example, 1 degree or greater, depending on the size of the three-phase AC electric wire 1. The intervals (θgi, θgo) occupied by the inner insulated section GI and the outer insulated section GO may be 2 degrees or greater, 3 degrees or greater, 4 degrees or greater, or even 5 degrees or greater. The intervals (θgi, θgo) occupied by the inner insulated section GI and the outer insulated section GO are, for example, 30 degrees or less. The intervals (θci, θgi) occupied by the inner insulated section GI and the outer insulated section GO may be 25 degrees or less, 20 degrees or less, or 15 degrees or less. The values ​​of the sections occupied by the inner insulating section GI and the outer insulating section GO can be determined as the angle at which lines extending from the respective end edges of two adjacent arc-shaped conductors C in the circumferential direction DR in the cross section intersect with each other to the central axis CAX.

[0025] In the cross section, the section (θci) occupied by the first inner conductor CI1, the second inner conductor CI2, and the third inner conductor CI3 constituting the inner conductor CI while going around the central axis CAX 360 degrees along the inner conductor CI, and the section (θco) occupied by the first outer conductor CO1, the second outer conductor CO2, and the third outer conductor CO3 constituting the outer conductor CO while going around the outer conductor CO can be, for example, 119 degrees or less. The section (θci) occupied by the first inner conductor CI1, the second inner conductor CI2, and the third inner conductor CI3 and the section (θco) occupied by the first outer conductor CO1, the second outer conductor CO2, and the third outer conductor CO3 may be, for example, 118 degrees or less, 117 degrees or less, 116 degrees or less, or 115 degrees or less. The section (θci) occupied by each of the first inner conductor CI1, the second inner conductor CI2, and the third inner conductor CI3 and the section (θco) occupied by each of the first outer conductor CO1, the second outer conductor CO2, and the third outer conductor CO3 can be, for example, 90 degrees or more. The section (θci) occupied by each of the first inner conductor CI1, the second inner conductor CI2, and the third inner conductor CI3 and the section (θco) occupied by each of the first outer conductor CO1, the second outer conductor CO2, and the third outer conductor CO3 may be 95 degrees or more, 100 degrees or more, or 105 degrees or more. The values ​​of the section (θci) occupied by each of the first inner conductor CI1, the second inner conductor CI2, and the third inner conductor CI3 and the section (θco) occupied by each of the first outer conductor CO1, the second outer conductor CO2, and the third outer conductor CO3 can be determined as the angle at which lines extending from both end edges of each arc-shaped conductor C in the circumferential direction DR to the central axis CAX intersect in the cross section.

[0026] The inner insulating sections GI and the outer insulating sections GO may all have the same section length in the circumferential direction DR or may have different section lengths. However, it is preferable that the three insulating sections G, the inner first insulating section GI1, the inner second insulating section GI2, and the inner third insulating section GI3, have a section length in the circumferential direction that is common to some extent, and it is also preferable that the three insulating sections G, the outer first insulating section GO1, the outer second insulating section GO2, and the outer third insulating section GO3, have a section length in the circumferential direction DR that is common to some extent.

[0027] Each of the three sections (θgi) of the first inner insulating section GI1, the second inner insulating section GI2, and the third inner insulating section GI3 is set to within ±15% of the average value of the three sections (θgi), for example. Each of the three sections (θgi) may be within ±10% or ±5% of the average value. Each of the three sections (θgo) of the first outer insulating section GO1, the second outer insulating section GO2, and the third outer insulating section GO3 is set to within ±15% of the average value of the three sections (θgo), for example. Each of the three sections (θgo) may be within ±10% or ±5% of the average value.

[0028] The sections (θci) occupied by the first inner conductor CI1, the second inner conductor CI2, and the third inner conductor CI3 and the sections (θco) occupied by the first outer conductor CO1, the second outer conductor CO2, and the third outer conductor CO3 may all be the same or different. However, it is preferable that the section lengths of the first inner conductor CI1, the second inner conductor CI2, and the third inner conductor CI3 in the circumferential direction DR are common to some extent. It is also preferable that the section lengths of the first outer conductor CO1, the second outer conductor CO2, and the third outer conductor CO3 in the circumferential direction DR are common to some extent. Each of the three sections (θci) occupied by the first inner conductor CI1, the second inner conductor CI2, and the third inner conductor CI3 is, for example, within ±15% of the average value of the three sections (θci). Each of the three sections (θci) may be within ±10% or ±5% of the average value. Furthermore, each of the three sections (θco) occupied by the first outer conductor CO1, the second outer conductor CO2, and the third outer conductor CO3 is set to, for example, within ±15% of the average value of the three sections (θco). Each of the three sections (θco) may be set to within ±10% or ±5% of the average value.

[0029] The thickness (dimension in the radial direction DD) of each of the first inner conductor CI1, the second inner conductor CI2, and the third inner conductor CI3 preferably does not vary in the circumferential direction, and the difference (variation range) between the thickest and thinnest points is preferably within 15% of the average thickness of the three arc-shaped conductors C. The variation range may be within 10%, or may be within 5%. The thickness (dimension in the radial direction DD) of each of the first outer conductor CO1, the second outer conductor CO2, and the third outer conductor CO3 preferably does not vary in the circumferential direction, and the difference (variation range) between the thickest and thinnest points is preferably within 15% of the average thickness of the three arc-shaped conductors C. The variation range may be within 10%, or may be within 5%. It is also preferable that the distance in the radial direction DD between the inner conductor CI and the outer conductor CO (the thickness in the radial direction DD of the first insulating layer S1) does not vary in the circumferential direction, and the difference (fluctuation range) between the farthest and closest distances is preferably within 15% of the average distance, for example. The fluctuation range may be within 10% or 5%.

[0030] Preferably, each inner insulated section GI is located at the center in the circumferential direction DR of the arc-shaped conductor C that constitutes the outer conductor CO, and each outer insulated section GO is located at the center in the circumferential direction DR of the arc-shaped conductor C that constitutes the inner conductor CI. More specifically, it is preferred that the midpoint of the distance between adjacent arc-shaped conductors C in the inner conductor CI is located at the center in the circumferential direction DR of the arc-shaped conductor C that constitutes the outer conductor CO, and that the midpoint of the distance between adjacent arc-shaped conductors C in the outer conductor CO is located at the center in the circumferential direction DR of the arc-shaped conductor C that constitutes the inner conductor CI.

[0031] Specifically, as shown in Fig. 3, in the wire main body 10 of this embodiment, it is preferable that all of the arc-shaped conductors C constituting the outer conductor CO are arranged so that a first imaginary line segment L11 extending from the central axis CAX to pass through a midpoint in the circumferential direction DR of the arc-shaped conductor C and a second imaginary line segment L12 extending from the central axis CAX to pass through a midpoint in the circumferential direction DR of an inner insulated section GI located radially inward of the arc-shaped conductor C are substantially overlapped. The angle (Δθ1) formed between the first imaginary line segment L11 and the second imaginary line segment L12 is preferably 5 degrees or less. The angle (Δθ1) formed between the first imaginary line segment L11 and the second imaginary line segment L12 may be 4 degrees or less, 3 degrees or less, or 2 degrees or less. The angle (Δθ1) formed by the first virtual line segment L11 and the second virtual line segment L12 may be equal to or less than 1 degree, or may be 0 degree.

[0032] Similarly to the above, in the wire main body 10 of this embodiment, the angle (Δθ2) formed by a first imaginary line segment L21 extending from the central axis CAX to pass through a midpoint in the circumferential direction DR of the arc-shaped conductor C constituting the inner conductor CI and a second imaginary line segment L22 extending from the central axis CAX to pass through a midpoint in the circumferential direction DR of the outer insulated section GO located radially outward of the arc-shaped conductor C is preferably 5 degrees or less. This angle (Δθ2) may be 4 degrees or less, 3 degrees or less, or 2 degrees or less. The angle (Δθ2) formed by the first imaginary line segment L21 and the second imaginary line segment L22 may be 1 degree or less, or may be 0 degree.

[0033] The thickness of the arc-shaped conductor C in the radial direction DD can be set appropriately depending on the maximum current value and frequency of the AC current being passed through it. It is preferable that the thickness in the radial direction DD is equal to or less than the skin depth. That is, when the thickness in the radial direction DD is "t," the electrical resistivity of the arc-shaped conductor C is "ρ," the angular frequency of the AC current is "ω," and the magnetic permeability is "μ," it is preferable that the arc-shaped conductor C has a thickness that satisfies the following formula (1): t ≦ (2ρ / ωμ) 0.5 ···(1)

[0034] In the wire body 10 of this embodiment, as shown in Fig. 4, the three arc-shaped conductors C constituting the inner conductor CI and the three arc-shaped conductors C constituting the outer conductor may be parallel to each other and extend straight in the longitudinal direction DL of the wire body 10, or as shown in Fig. 5, three inner and three outer arc-shaped conductors C may extend in the longitudinal direction DL while spiraling around the central axis CAX while maintaining a parallel state. When the arc-shaped conductors C in a straight state as shown in Fig. 4 are provided, it is easy to align the inner and outer insulating sections G and the arc-shaped conductors C in the circumferential direction DR, and it is easy to achieve the above-mentioned preferable state. On the other hand, when a straight arc-shaped conductor C is provided as shown in Figure 4, the arc-shaped conductors C of the same phase are positioned 180 degrees apart inside and outside. However, when the arc-shaped conductor C is provided in a spiral shape as shown in Figures 5a and 5b, the first insulating layer S1 and the portion radially outward of the first insulating layer S1 are removed at the terminal to expose the arc-shaped conductor C constituting the inner conductor CI, and the second insulating layer S2 and the sheath portion 20 radially outward of the second insulating layer S2 are removed to expose the arc-shaped conductor C constituting the outer conductor CC. This can be done at different points in the length direction DL, so that the positions of the arc-shaped conductors C of the same phase inside and outside can be aligned in the circumferential direction DR. Therefore, providing the arc-shaped conductor C in a spiral shape as shown in Figures 5a and 5b can facilitate wiring at the terminal.

[0035] To explain this point in more detail with reference to Figure 5b, if the arc-shaped conductors C that constitute each of the inner conductor CI and the outer conductor CO are made to rotate in a common direction (clockwise, counterclockwise) around the central axis CAX and extend spirally in the longitudinal direction DL, then by exposing the inner and outer arc-shaped conductors C, through which AC current of the same phase flows, such as the third inner conductor CI3 and the third outer conductor CO3, at a predetermined distance in the longitudinal direction DL, their positions in the circumferential direction DR can be aligned.

[0036] Specifically, when the three-phase AC wire 1 illustrated in Figures 5a and 5b is moved in the longitudinal direction DL along the spiral arc-shaped conductor C that constitutes the outer conductor CO, the distance it moves in the longitudinal direction DL before it turns 360 degrees around the central axis CAX and returns to its original position in the circumferential direction DR is defined as the winding pitch (L: mm), and if the inner conductor CI and the outer conductor CO are exposed in the longitudinal direction DL at a distance of about half the winding pitch L (L / 2 (mm)), the inner and outer arc-shaped conductors C through which currents of the same phase flow can be aligned in the circumferential direction DR.

[0037] As described above, the three-phase AC electric wire 1 illustrated in FIGS. 5a and 5b is configured such that a conductor pair is formed by selecting arc-shaped conductors C constituting the inner conductor CI and arc-shaped conductors C constituting the outer conductor CO, through which AC currents of the same phase flow, from each of the arc-shaped conductors C constituting the inner conductor CI and the arc-shaped conductors C constituting the outer conductor CO, a first connection point P1 is set on one of the conductor pair (e.g., the third inner conductor CI3), and a second connection point P2 is set on the other of the conductor pair (e.g., the third outer conductor CO3), and when performing terminal processing to electrically connect the second connection point P2 and the first connection point P1, the positions of the first connection point P1 and the second connection point P2 can be aligned in the circumferential direction DR, making terminal processing easy.

[0038] The ratio (L / D) of the winding pitch (L: mm) of the arc-shaped conductor C constituting the outer conductor CO to the outer diameter D (mm) of the outer conductor CO is, for example, 30 or less. The ratio (L / D) may be 25 or less, or may be 20 or less. The ratio (L / D) is, for example, 5 or more. When the central axis CAX of the three-phase AC electric wire 1 is viewed from a direction perpendicular to the longitudinal direction DL, the arc-shaped conductor C constituting the outer conductor CO can be shaped so that the angle θt formed between the direction DS along its spiral and the central axis CAX is, for example, 5 degrees or more. The arc-shaped conductor C constituting the outer conductor CO may have a spiral shape such that the angle θt formed with respect to the central axis CAX is 10 degrees or more, or may be a spiral shape such that the angle θt formed with respect to the central axis CAX is, for example, 45 degrees or less. The arc-shaped conductor C may be provided in various other forms in the three-phase AC electric wire 1 of this embodiment.

[0039] The arc-shaped conductor C can be made of a material used for general electric wires. The arc-shaped conductor C can be made using multiple strands (annealed copper wires). When multiple strands are used, the arc-shaped conductor C can be made by pulling the multiple strands together in an arc shape, or by twisting multiple strands together and arranging the twisted wires in an arc shape. The arc-shaped conductor C can also be made of a flat copper wire curved into a trough shape. The flat copper wire may be a thin one called copper tape. The flat copper wire may also be a braided wire in which multiple strands are woven into a band shape.

[0040] The insulating core S0, the first insulating layer S1, the second insulating layer S2, and the insulating section G are made of a material having a volume resistivity of 1×10 at room temperature and room humidity (for example, 23° C., 50% RH). 13The insulating core S0, the first insulating layer S1, the second insulating layer S2, and the insulating section G may be filled with a resin composition having an electrical insulation property of Ω·cm or more in a non-foamed or foamed state. The insulating core S0, the first insulating layer S1, the second insulating layer S2, and the insulating section G may simply have spaces formed therein by providing spacers scattered in the length direction DL. Furthermore, these may be filled with interposing materials such as kraft interposing paper, nonwoven tape, PP yarn, jute, or blended yarn. The first insulating layer S1 and the second insulating layer S2 may also be provided with multiple sheets of resin film or insulating paper stacked in the radial direction DD.

[0041] Ensuring insulation by filling with non-foaming resin or foaming resin is effective in preventing water from seeping in from the end of the three-phase AC wire 1, which could cause the interphase insulation to be lost, and the use of spacers or interposers is effective in reducing the weight of the three-phase AC wire 1.

[0042] The insulating core S0, the first insulating layer S1, the second insulating layer S2, and each insulating section G may be made of the same or different materials. The first insulating layer S1 is preferably configured to have a high compressive stress so that the distance between the inner conductor CI and the outer conductor CO can be prevented from changing even when bending stress is applied in a specific direction within the radial direction DD when the three-phase AC electric wire 1 is bent. The first insulating layer S1 may be made of, for example, a foam, a non-foam, or a resin film with an expansion ratio of approximately 5 times or less. When the first insulating layer S1 is made of, for example, a resin foam or a non-foam, it may be made of a resin composition containing, as a main component, a crosslinked or non-crosslinked polyethylene resin, a polypropylene resin, a polyvinyl chloride resin, a fluororesin, or the like. When the first insulating layer S1 is made of, for example, a resin film (resin tape), it may be made of, for example, a polyethylene terephthalate resin film (PET tape) or a polyimide resin film (Kapton tape (product name)).

[0043] The three-phase AC electric wire 1 can be manufactured using an extruder or the like, similarly to a general electric wire. The three-phase AC electric wire 1 can be manufactured, for example, by a method in which an inner conductor CI is formed by longitudinally attaching an adhesive-backed copper tape to the outer peripheral surface of a long, round rod-shaped member constituting the insulating core S0, and the resulting product is passed through a nipple of an extruder as a primary core material, and an electrically insulating resin composition is extruded to coat the primary core material to form an inner insulating section GI and a first insulating layer S1, and an outer conductor CO is formed by longitudinally attaching an adhesive-backed copper tape to the outer peripheral surface of the obtained long, round rod-shaped extruded product to form a secondary core material, and the secondary core material is again passed through the nipple of the extruder to form an outer insulating section GO and a second insulating layer S2 in a secondary extrusion step to obtain the electric wire main body 10, and the electric wire main body 10 is then passed through the extruder to coat the sheath portion 20. In addition, in the primary extrusion process, a protrusion (outer insulating section GO) for guiding the position where the outer conductor CO is to be provided may also be formed, and in the secondary extrusion process, only the second insulating layer S2 may be extrusion coated.

[0044] In addition to the above-described method, the three-phase AC electric wire 1 can be fabricated by extruding an electrically insulating resin composition to form a long, round rod-shaped member with three continuous ridges along its outer periphery (a member with a gear-like cross-section with only three teeth). A rectangular copper wire is then placed in the grooves between the ridges so that it has an arc-shaped cross section, and the electrically insulating resin composition is then extruded to form the portion of the wire body 10 extending from the center to the first insulating layer S1. At this time, the ridges that will become the outer insulating section GO may also be formed. The three-phase AC electric wire 1 can then be fabricated by providing an outer conductor CO and covering it with the second insulating layer S2 and sheath 20 in the same manner as described above.

[0045] In this embodiment, the three-phase AC electric wire 1 is exemplified as having the above-described structure, and the above-described manufacturing method is exemplified as an example of the manufacturing method thereof. However, the three-phase AC electric wire can take various forms other than those exemplified above, and the manufacturing method is not limited to the above-exemplified method in any way.

[0046] For example, in this embodiment, the inner conductor CI and the outer conductor CO are each exemplified as being a cylindrical conductor divided into three parts in the circumferential direction, but as long as the arc-shaped conductors C, through which the u, v, and w phases of a three-phase AC flow, are arranged in sequence in the circumferential direction DR and each arc-shaped conductor C is arranged so as to face in the radial direction DD arc-shaped conductors C through which two phases different from the phase flowing through the arc-shaped conductor C, each of the inner conductor CI and the outer conductor CO may be such that a cylindrical conductor is divided into 3n pieces (n represents a natural number (1, 2, 3, etc.)), and each of the inner conductor CI and the outer conductor CO may be such that six arc-shaped conductors C, namely, u, v, w, u, v, and w phases, are arranged concentrically in the circumferential direction, or such that nine arc-shaped conductors, namely, u, v, w, u, v, w, u, v, and w phases, are arranged concentrically.

[0047] As mentioned above, this specification includes the following disclosures.

[0048] [1] A three-phase AC electric wire through which three-phase AC is passed, a plurality of arc-shaped conductors having a length direction and having an arc-shaped cross section perpendicular to the length direction; The plurality of arc-shaped conductors include: The two concentric circles are arranged side by side in the circumferential direction so as to form two concentric circles on the cross section, an inner conductor arranged to form an inner circle of the concentric circles; an outer conductor arranged to form an outer circle of the concentric circles, In each of the inner conductor and the outer conductor, The arc-shaped conductors adjacent to each other in the circumferential direction are arranged at a distance from each other, The arc-shaped conductors through which the u-phase, v-phase, and w-phase of the three-phase AC flow are arranged in order in the circumferential direction, Each of the arc-shaped conductors has: the arc-shaped conductor is disposed so as to face the arc-shaped conductor in the radial direction, through which two phases different from the phases flowing through the arc-shaped conductor; The arc-shaped conductor faces, at one end side in the circumferential direction, the arc-shaped conductor through which one of two phases different from the phase flowing through the arc-shaped conductor flows, A three-phase AC electric wire that faces, at the other end in the circumferential direction, an arc-shaped conductor through which the other of two phases different from the phase flowing through the arc-shaped conductor flows.

[0049] [2] The arc-shaped conductors constituting the inner conductor and the outer conductor are a midpoint of the distance between the arc-shaped conductors in the inner conductor is located at a center in the circumferential direction of the arc-shaped conductor constituting the outer conductor, [1] A three-phase AC electric wire according to [1], wherein the midpoint of the distance between the arc-shaped conductors in the outer conductor is positioned at the center in the circumferential direction of the arc-shaped conductor constituting the inner conductor.

[0050] [3] The three-phase AC electric wire according to [1] or [2], wherein the arc-shaped conductors constituting the inner conductor and the outer conductor respectively extend spirally in the length direction. [Example]

[0051] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. (Example, Comparative Example 1, Comparative Example 2) A simulation was performed using three three-phase AC electric wires, Comparative Example 1, Comparative Example 2, and Example, under the conditions shown in Fig. 6a. The three-phase AC electric wires of Comparative Example 1, Comparative Example 2, and Example had the same conductor size and finished diameter. In the simulation, the conductor resistance value (conductor resistance) when a 50 kHz three-phase AC is passed through compared to when a DC current is passed through, the ratio to when a DC current is passed through (conductor resistance increase rate), and the inductance, reactance, and impedance when a 50 kHz three-phase AC is passed through were also calculated.

[0052] The results are shown in Figure 6b, and it was found that the three-phase AC electric wire of the example was excellent in all of inductance, reactance, and impedance. This also shows that the present invention can provide a three-phase AC electric wire with reduced inductance.

[0053] (Comparative Example 3 and Comparative Example 4) Furthermore, a simulation was performed using three-phase AC electric wires of Comparative Examples 3 and 4 under the conditions shown in Fig. 7a. The results are shown in Fig. 7b. From these results, it was confirmed that the three-phase AC electric wire of the example was superior to Comparative Examples 3 and 4 in all of inductance, reactance, and impedance. This also shows that the present invention can provide a three-phase AC electric wire with reduced inductance. [Explanation of symbols]

[0054] 1: 3-phase AC wire, 10: wire body, 20: sheath, CAX: central axis, C: Arc-shaped conductor, CI: Inner conductor, CI1: First inner conductor, CI2: Second inner conductor, CI3: Third inner conductor, CO: outer conductor, CO1: first outer conductor, CO2: second outer conductor, CO3: third outer conductor, G: Insulated section, GI: inner insulation section, GI1: first inner insulation section, GI2: second inner insulation section, GI3: third inner insulation section, GO: outer insulating section, GO1: first outer insulating section, GO2: second outer insulating section, GO3: third outer insulating section, S0: insulating core; S1: first insulating layer; S2: second insulating layer; DL: Lengthwise direction, DD: Radial direction, DR: Circumferential direction, VP: Virtual plane

Claims

1. A three-phase AC electric wire through which three-phase AC is passed, a plurality of arc-shaped conductors having a length direction and having an arc-shaped cross section perpendicular to the length direction; The plurality of arc-shaped conductors include: The two concentric circles are arranged side by side in the circumferential direction so as to be drawn on the cross section, an inner conductor arranged to form an inner circle of the concentric circles; an outer conductor arranged to form an outer circle of the concentric circles, In each of the inner conductor and the outer conductor, The arc-shaped conductors adjacent to each other in the circumferential direction are arranged at a distance from each other, The arc-shaped conductors through which the u-phase, v-phase, and w-phase of the three-phase AC flow are arranged in order in the circumferential direction, Each of the arc-shaped conductors has: the arc-shaped conductor is disposed so as to face the arc-shaped conductor in the radial direction, through which two phases different from the phases flowing through the arc-shaped conductor; the arc-shaped conductor faces, at one end side in the circumferential direction, the arc-shaped conductor through which one of two phases different from the phase flowing through the arc-shaped conductor flows; a three-phase AC electric wire, the other end of which faces the arc-shaped conductor through which the other of two phases different from the phase flowing through the arc-shaped conductor flows;

2. The arc-shaped conductors constituting the inner conductor and the outer conductor are a midpoint of the distance between the arc-shaped conductors in the inner conductor is located at a center in the circumferential direction of the arc-shaped conductor constituting the outer conductor, 2. The three-phase AC electric wire according to claim 1, wherein the intermediate point of the distance between the arc-shaped conductors in the outer conductor is positioned at a center in the circumferential direction of the arc-shaped conductor constituting the inner conductor.

3. 3. The three-phase AC electric wire according to claim 1, wherein the arc-shaped conductors constituting the inner conductor and the outer conductor extend spirally in the length direction.

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