JP2022140437A - Wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wire excellent in reduction of loss due to skin effect and proximity effect as compared with the prior art.

SOLUTION: A wire includes a conductor whose cross-sectional shape is non-circular in a plane orthogonal to the length direction, and the cross-sectional shape includes an upper region which is a region from the center to the upper side in the vertical direction and is formed so as to bend in any one of the left and right directions, and a lower region which is a region from the center to the lower side in the vertical direction and is formed to bend in the same direction as the upper region.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to electric wires, and more particularly to electric wires used in coils.

2. Description of the Related Art Conventionally, an electric wire having a conductor having a circular cross-sectional shape on a plane perpendicular to the length direction has been widely used. However, such electric wires are known to cause uneven distribution of current flow due to the skin effect and the proximity effect. For this reason, when an alternating current is passed through such an electric wire, there is a problem that a loss is generated due to these effects, and the power transmission efficiency is lowered.

Therefore, reduction of the loss in electric wires has been studied (for example, Patent Document 1).

JP 2019-79870 A

However, the electric wire described in Patent Literature 1 has a problem that the loss due to the skin effect and the proximity effect is not sufficiently reduced. Specifically, when the inventors of the present invention examined the cross-sectional shape of the conductor, they found that the difference in the cross-sectional shape causes a portion in the conductor where backflow current is likely to occur, and the loss increases due to this backflow current. Found it.

In view of the above problems, an object of the present invention is to provide an electric wire that is superior in reducing losses due to the skin effect and the proximity effect as compared with the prior art.

The electric wire according to the present invention is
A conductor having a non-circular cross-sectional shape in a plane orthogonal to the length direction,
The cross-sectional shape includes an upper region that is a region above the center in the vertical direction and is formed to bend in one of the left and right directions, and a region below the center in the vertical direction that is the same as the upper region. and a lower region formed to bend in a direction.

According to such a configuration, since the cross-sectional shape of the conductor is formed as described above, reverse current is less likely to occur when wires are arranged in parallel when forming a coil. Therefore, losses due to skin effect and proximity effect are reduced.

The electric wire is preferably
In the cross-sectional shape, each of the upper region and the lower region is formed in a curved line, or linearly extends in a direction inclined with respect to the vertical direction.

According to such a configuration, each of the upper region and the lower region in the cross-sectional shape of the conductor is formed in a curved line or extends linearly in a direction inclined with respect to the vertical direction. Backflow current is less likely to occur, and loss is further reduced.

The electric wire is preferably
The cross-sectional shape has a corner curved in the one direction, and the outside of the corner is chamfered.

Here, when the cross-sectional shape of the conductor has a sharp portion, the current tends to be unevenly distributed at this portion, resulting in a large loss.
Therefore, according to such a configuration, since the uneven distribution of current in the conductor is suppressed by the fact that the outside of the corners in the cross-sectional shape of the conductor is chamfered, the loss is more reliably reduced.

Further, the coil according to the present invention is a coil in which an electric wire is wound a plurality of times,
The electric wire arranged at least on the innermost circumference of the coil is any of the electric wires described above, and the upper region and the lower region in the cross-sectional shape of the conductor are bent away from the central axis of the coil. are distributed.

According to such a configuration, the electric wire arranged at least on the innermost circumference of the coil is arranged such that the upper region and the lower region in the cross-sectional shape of the conductor are bent away from the central axis of the coil. As a result, backflow current is less likely to occur, and losses due to the skin effect and proximity effect are reduced.

Further, the coil according to the present invention preferably has
The electric wire arranged at least on the outermost circumference of the coil is any of the electric wires described above, and is arranged so that the upper region and the lower region in the cross-sectional shape of the conductor are bent toward the central axis of the coil. It is

According to such a configuration, the electric wire arranged at least on the outermost circumference of the coil is arranged such that the upper region and the lower region in the cross-sectional shape of the conductor are bent toward the central axis of the coil. As a result, uneven distribution of current is suppressed, and loss is further reduced.

As described above, according to the present invention, it is possible to provide an electric wire that is excellent in reducing loss due to the skin effect and the proximity effect as compared with the prior art.

FIG. 1 shows a schematic plan view of a coil formed by an electric wire according to one embodiment. FIG. 2 shows a cross-sectional shape of a conductor included in an electric wire according to one embodiment. FIG. 3 shows the cross-sectional shape of another embodiment of the conductor. FIG. 4 shows a cross-sectional shape of an electric wire in which the entire conductor is covered with a covering material. FIG. 5 shows a cross-sectional shape of an electric wire in which a part of the conductor is covered with a covering material. FIG. 6 shows a cross-sectional shape of an electric wire in which a plurality of conductors are covered with one insulating material. FIG. 7 shows an arrangement example of electric wires (conductors) in a coil. FIG. 8 shows a more preferable arrangement example of electric wires (conductors) in the coil. FIG. 9 shows the cross-sectional shape of another embodiment of the conductor. 10 shows the current distribution at 100 kHz in the conductor of the electric wire in Comparative Example 1. FIG. 11 shows the current distribution at 100 kHz in the conductor of the electric wire in Comparative Example 2. FIG. FIG. 12 shows the current distribution at 100 kHz in the conductors of each electric wire in Reference Examples 1-6. FIG. 13 shows the current distribution at 100 kHz in the conductors of each electric wire in Reference Examples 7-12. FIG. 14 shows the current distribution at 100 kHz in the conductors of each electric wire in Reference Examples 13 to 18 and Reference Example 27. FIG. FIG. 15 shows the current distribution at 100 kHz in the conductors of each electric wire in Reference Examples 19-26.

An electric wire according to an embodiment of the present invention will be described below with reference to the drawings.

The electric wire 1 of this embodiment is used to form a coil 100 as shown in FIG. A coil 100 formed by the electric wire 1 of this embodiment has a winding portion 110 in which the electric wire 1 is wound a plurality of times. That is, the coil 100 has the electric wire 1 arranged so as to go around the central axis. The central axis of coil 100 passes through the winding center of winding portion 110 . In the winding portion 110, the electric wire 1 is arranged along a plane perpendicular to the central axis. The electric wire 1 is arranged so as to revolve around the central axis. In other words, in this embodiment, the electric wire 1 is spirally formed at the winding portion 110 .
In the following, the direction along the central axis will be referred to as the vertical direction, and the radial direction orthogonal to the central axis will be referred to as the lateral direction. Also, hereinafter, the direction away from the central axis may be referred to as the outward direction, and the direction approaching the central axis may be referred to as the inward direction.

In this embodiment, the winding portion 110 has a constant interval d between the electric wires 1 in the radial direction. In addition, in this embodiment, the space|interval d shall mean the center-to-center distance of the electric wire 1. FIG.

As shown in FIG. 2, the electric wire 1 includes a conductor 10 having a non-circular cross-sectional shape A on a plane orthogonal to the length direction.

The conductor 10 has a cross-sectional shape A that, when the coil 100 is formed, avoids or circumvents locations where reverse current flows easily and locations where current does not readily flow. That is, the cross-sectional shape A includes an upper region 11 that is a region above the center in the vertical direction and is curved in one of the left and right directions (rightward in FIG. 2), and a region below the center in the vertical direction. and has a lower region 12 formed so as to bend in the same direction as the upper region 11 . In this embodiment, the cross-sectional shape A is formed so that the upper region 11 and the lower region 12 have the same shape. In other words, the upper region 11 and the lower region 12 are formed so as to be line-symmetrical with respect to the boundary line that separates them.

The cross-sectional shape A has an upper end portion 15 and a lower end portion 16 as tip portions of the upper region 11 and the lower region 12, respectively. If the upper end portion 15 and the lower end portion 16 are tapered, the current tends to be unevenly distributed in this portion, and this phenomenon becomes noticeable particularly when the coil 100 is formed. Therefore, the upper end portion 15 and the lower end portion 16 are preferably tapered so as to be rounded as a whole.

The cross-sectional shape A has an inner peripheral edge 13 and an outer peripheral edge 14 by forming the upper region 11 and the lower region 12 to bend in the same direction. In order to suppress the occurrence of backflow current in the conductor 10 and uneven distribution of the current, it is preferable that at least the outer peripheral edge 14 is formed in an arc shape. Moreover, it is more preferable that both the inner peripheral edge 13 and the outer peripheral edge 14 are formed in an arc shape. Further, the cross-sectional shape A is preferably formed so that the interval t between the inner peripheral edge 13 and the outer peripheral edge 14 is constant.

When the inner peripheral edge 13 and/or the outer peripheral edge 14 are formed in an arc shape, the ratio of the loss increase rate to the electric wire having a circular cross-sectional shape of the conductor at 100 kHz in the example described later (whether the interval d is 3 mm or 6 mm Regardless), the central angle θ _S is preferably 15 to 210°, more preferably 15 to 195°, even more preferably 30 to 180°, most preferably 75 to 135°. preferable. By setting the central angle θ _S to the above value, the generation of reverse current in the conductor 10 can be more effectively suppressed. In addition, particularly when forming a coil, it is possible to efficiently arrange the conductor 10 so as to avoid or detour places where it is difficult for current to flow.
The central angle θ _S is calculated, for example, as an arithmetic mean value of the measured values of the angles in the cross-sectional shape A at ten arbitrary positions of the electric wire 1 .

The distance t between the inner peripheral edge 13 and the outer peripheral edge 14 is preferably less than twice the skin depth (the depth at which the current is 1/e of the surface current) at the operating frequency. This has the effect of making it difficult for reverse current to flow. When the distance t between the inner peripheral edge 13 and the outer peripheral edge 14 is constant, and the distance from the center C of the arc formed by the inner peripheral edge 13 to the inner peripheral edge 13 is r, the ratio of the distance r to the interval t is It is calculated from the interval t, the central angle θ _S and the required conductor cross-sectional area (area of the cross-sectional shape A).
For example, if a conductor made from sheet copper requires a conductor cross-sectional area equivalent to 2 mm ² at a frequency of 100 kHz, then t = 0.4 mm (approximately twice the 0.21 mm skin depth of copper at 100 kHz). If the central angle θ _S is 90° when the copper plate of 1 is used as the conductor, the distance r is about 2.98 mm, and the ratio of the distance r to the interval t is about 7.46.
Note that the interval t and the distance r are calculated, for example, as an arithmetic mean value of each measured value in the cross-sectional shape A at ten arbitrary positions of the electric wire 1 .

As shown in FIG. 3, the cross-sectional shape A is a V-shape in which each of the upper region 11 and the lower region 12 extends linearly in a direction inclined with respect to the vertical direction. shape). In this case, the cross-sectional shape A has corners 17 between the upper region 11 and the lower region 12 . If the corner 17 is sharp, the current tends to be unevenly distributed in this portion. A chamfered shape is preferred. Moreover, the cross-sectional shape A is preferably formed so that the interval t between the inner peripheral edge 13 and the outer peripheral edge 14 is constant.

According to the ratio of the loss increase rate to that of an electric wire having a circular conductor cross-section at 100 kHz in an example described later (regardless of whether the interval d is 3 mm or 6 mm), the angle θ _V formed inside the corner 17 is It is preferably 90 to 165°, more preferably 105 to 165°, even more preferably 120 to 150°.

The distance t between the inner peripheral edge 13 and the outer peripheral edge 14 is preferably less than twice the skin depth (the depth at which the current is 1/e of the surface current) at the operating frequency. This has the effect of making it difficult for reverse current to flow. In FIG. 3, the cross-sectional shape A is formed so that the interval t between the inner peripheral edge 13 and the outer peripheral edge 14 is constant. In this case, when half the length of the inner peripheral edge 13 is defined as l, the ratio of the length l to the interval t is the angle _θV formed between the interval t and the corner 17. It is calculated by the conductor cross-sectional area (area of cross-sectional shape A).
For example, if a conductor made from sheet copper requires a conductor cross-sectional area equivalent to 2 mm ² at a frequency of 100 kHz, then t = 0.4 mm (approximately twice the 0.21 mm skin depth of copper at 100 kHz). If the angle θ _V is 90° when using a copper plate as a conductor, the length l is 2.3 mm and the ratio of the length l to the interval t is 5.75.

Examples of materials for forming the conductor 10 include flat braided copper wires, copper plates, and copper tapes, and metals other than copper can also be used. Also, the conductor 10 may be a litz wire formed by twisting strands of wire, and in this case, each strand may be coated with an insulation.
In order to form the coil 100 used at relatively low frequencies, the conductor 10 is preferably made of a flat braided litz wire. The low frequency is preferably less than 1 MHz, more preferably less than 100 kHz.
On the other hand, in order to form the coil 100 used at relatively high frequencies, i.e., high frequencies, the conductor 10 is preferably made of flat braided copper wire. The high frequency is preferably a frequency of 1 MHz or higher, more preferably a frequency of 5 MHz or higher.
The reason why the flat woven copper wire is preferable to the flat woven litz wire at the high frequency is that, in the flat woven litz wire, the current distribution is biased at a high frequency where the skin thickness is smaller than the wire diameter. 2) The proximity effect between individual strands makes it easier for a reverse current to flow inside the strands, and as a result, the flat braided litz wire tends to increase the loss. On the other hand, in the case of flat braided copper wires, since the wires are short-circuited, the proximity effect between the wires is less likely to occur, and as a result, the loss is less likely to increase.

The electric wire 1 may or may not have the conductor 10 covered with the insulating material 20 (that is, the conductor 10 may be a bare conductor).

When the conductor 10 is covered with the insulating material 20 , the entire conductor 10 may be completely covered with the insulating material 20 . For example, as shown in FIG. 4( a ), the cross-sectional shape B in the plane orthogonal to the length direction of the electric wire 1 is such that the peripheral edge of the conductor 10 and the peripheral edge of the insulating material 20 correspond to each other. good. In addition, as shown in FIG. 4B, the cross-sectional shape B may have a rectangular peripheral edge of the insulating material 20 .

Moreover, when the conductor 10 is covered with the insulating material 20 , only a part of the conductor 10 may be covered with the insulating material 20 . For example, as shown in FIG. 5A, the cross-sectional shape B may be a shape such that the inner peripheral edge 13 of the conductor 10 is in contact with part of the outer peripheral edge of the hollow cylindrical insulator 20 . Further, as shown in FIG. 5B, the cross-sectional shape B may be a shape such that the outer peripheral edge 14 of the conductor 10 is in contact with part of the inner peripheral edge of the hollow cylindrical insulating material 20 . This facilitates constant adjustment of the distance d between the electric wires 1 in the winding portion 110 when the coil is formed. In addition, since the insulating material 20 has a hollow cylindrical shape, it becomes easy to cut off a part of the insulating material 20 as necessary, and the interval d between the electric wires 1 in the winding portion 110 at the time of forming the coil can be arbitrarily adjusted. becomes easier.

Furthermore, when the conductors 10 are covered with the insulating material 20, the plurality of conductors 10 may be covered with one insulating material 20 as shown in FIG. For example, in FIG. 6A, in the cross-sectional shape B, two conductors 10 are arranged so that the inner peripheral edge 13 and the outer peripheral edge 14 face each other, and one insulating material 20 having a rectangular peripheral edge is provided. covered. In FIG. 6B, in the cross-sectional shape B, the inner peripheral edges 13 of the two conductors 10 are arranged so as to face each other, and are covered with one insulating material 20 having a rectangular peripheral edge. . This can reduce loss when used at high frequencies as a two-core cable.

The material forming the insulating material 20 is not limited to the following, but is preferably an electrically insulating polymer composition, preferably a polymer composition having a volume resistivity of 1×10 ¹² Ω·cm or more. .

Next, an arrangement example of the electric wire 1 when the electric wire 1 according to the present embodiment forms the coil 100 will be described.

As shown in FIGS. 7 and 8, the electric wire 1 arranged at least on the innermost circumference of the winding portion 110 is such that the upper region 11 and the lower region 12 in the cross-sectional shape A of the conductor 10 are aligned with the center of the coil 100. It is arranged to bend away from the axis. As a result, backflow current and maldistribution of current in the wires arranged on the inner side of the coil 100 are effectively suppressed, thereby reducing loss. In addition, hereinafter, the state in which the upper region 11 and the lower region 12 are arranged so as to bend away from the central axis may be referred to as a first arrangement state O. As shown in FIG.
In addition, the electric wire 1 arranged at least on the outermost circumference of the winding portion 110 is arranged such that the upper region 11 and the lower region 12 in the cross-sectional shape A of the conductor 10 are bent toward the central axis of the coil 100. preferably. This effectively suppresses uneven distribution of current in the wires arranged on the outward side of the coil 100, thereby reducing loss. In addition, hereinafter, the state in which the upper region 11 and the lower region 12 are arranged so as to bend toward the central axis may be referred to as a second arrangement state I.

For example, in the arrangement example shown in FIG. 7, all the conductors 10 are in the first arrangement state O. As shown in FIG. In a more preferable arrangement example shown in FIG. 8, the inner conductors 10 including the innermost circumference are in the first arrangement state O, and the outer conductors 10 including the outermost circumference are in the second arrangement state. Arrangement state I is set. In other words, in the arrangement example of FIG. They are arranged so that the cross-sectional shape A is reversed (so that the inner peripheral edges 13 face each other). As a result, uneven distribution of current at the tip portions (upper end portion 15 and lower end portion 16) of the conductor 10 can be suppressed. Such inversion may be performed by twisting one electric wire 1 or by joining two electric wires 1 in an inverted state.

More specifically, when the electric wire 1 constituting the winding portion 110 is 1 . ) is in the first arrangement state O, and the wires 1 arranged on the outer side of the Mth are in the second arrangement state I. Note that M is a number rounded to an integer. In the arrangement example shown in FIG. 8, the first to seventh electric wires 1 are in the first arrangement state O, and the eighth to tenth electric wires 1 are in the second arrangement state I. . That is, in the arrangement example of FIG. 8, M=0.7N.
The optimum value of M can be appropriately changed according to the magnetic field surrounding the wire. For example, when the coil inner diameter is large, the optimum M is preferably close to 0.5N, and when the coil inner diameter is small, the optimum M is preferably close to N. For example, it has the _cross -sectional shape A shown in FIG. The electric wire 1 (reference example 18 in the embodiment) provided with the conductor 10 having a distance r = 10/π-0.2 mm (≈2.98 mm) to the peripheral edge 13 is arranged at a distance d = Regarding the coil 100 which is set to 3 mm and wound 10 times, assuming that a current of 1 A flows through the electric wire 1, when the inner diameter of the coil is 900 mm or more, the optimum M is 0.5 N, and the inner diameter of the coil is 0.5 N. When it is 12 mm or less, the optimum M is 0.9N. The ratio of the coil outer diameter to the coil inner diameter is 1.06 when the coil inner diameter is 900 mm (coil outer diameter 954 mm), and is 5.5 when the coil inner diameter is 12 mm (coil outer diameter 66 mm).

The coil 100 configured as described above can be suitably used as a contactless power feeding coil. Examples of non-contact power feeding coils include relatively small smartphone charging coils and relatively large electric vehicle battery charging coils. Also, in such a contactless power supply coil, an alternating current of 85 kHz is normally passed through, and the coil 100 of the present embodiment can be suitably used in applications where an alternating current of 10 kHz or higher or 100 kHz or higher is passed.

As described above, the embodiments are shown as examples, but the electric wires according to the present invention are not limited to the configurations of the above embodiments. Moreover, the electric wire according to the present invention is not limited by the above effects. Various modifications can be made to the electric wire according to the present invention without departing from the gist of the present invention.

For example, in the above-described embodiment, the cross-sectional shape A is arc-shaped or V-shaped, but the cross-sectional shape A may be C-shaped as shown in FIG. That is, in FIG. 9, the cross-sectional shape A includes a linear portion 18 formed so that each of the upper region 11 and the lower region 12 extends along the vertical direction from the center, and a straight portion 18 formed so as to bend from both ends of the straight portion 18. It has a pair of straight bends 19 formed thereon. In this case, the cross-sectional shape A has two corner portions 17 between the straight portion 18 and each curved portion 19 . In FIG. 9A, the angle θ _C formed inside the corner 17 is 90°, and in FIG. 9B, the angle θ _C is formed larger than 90°. At 100 kHz in the example, the angle θ _C is preferably from 90 to 165°, and from 120 to 165° is more preferred. If the corner 17 is sharp, the current tends to be unevenly distributed in this portion. A chamfered shape is preferred. As the number of the corners 17 of the cross-sectional shape A increases, the corners 17 of the cross-sectional shape A become more arcuate, and the uneven distribution of current is less likely to occur.

The present invention will be further illustrated by the following examples.

First, using analysis software Femtet (registered trademark) (Version 2018.1.2.70140), under the analysis conditions shown in Table 1, the cross-sectional shape of the conductor was evaluated. More specifically, assuming a coil in which an electric wire having a conductor having a cross-sectional shape A as shown in Table 2 is wound 10 times, and assuming that a current of 1 A flows through the electric wire, 1 Hz to A loss simulation was performed at each frequency of 100 MHz.
The inner diameter of the coil was set to 50 mm, and the interval d between the electric wires in the winding portion was set to 3 mm or 6 mm.
As for the coils of Reference Examples 1 to 26 in Table 2, all the 1st to 10th electric wires forming the winding portion were arranged in the first arrangement state O as shown in FIG. On the other hand, as for Reference Example 27, as shown in FIG. placed like this.
Tables 3 and 4 show the loss and loss increase rate at each frequency (the value obtained by dividing the loss at each frequency by the loss at 1 Hz), and the ratio of the loss increase rate for wires with circular cross-sectional conductors. rice field.

As shown in FIG. 10 (a case where the distance d is 3 mm), in Comparative Example 1 in which the cross-sectional shape of the conductor is circular, the conductor arranged on the inner side of the coil (especially the innermost circumference) A reverse current occurred on the side and an uneven distribution of current on the inward side was observed. In addition, as shown in FIG. 11, in Comparative Example 2 in which the cross-sectional shape of the conductor is I-shaped (linear), uneven distribution of the current was remarkable at the upper end and the lower end of the cross-sectional shape of the conductor. .
Due to these phenomena, as shown in Tables 3 and 4, in Comparative Examples 1 and 2, a relatively large loss was observed when an alternating current of 10 kHz or higher was applied.

On the other hand, as shown in FIGS. 12 to 15 (the distance d is 3 mm), the cross-sectional shape of the conductor is V-shaped Reference Examples 2-6, C-shaped Reference Examples 9-12, and arc-shaped In Reference Examples 13 to 25 and 27, it was observed that backflow current was less likely to occur, uneven distribution of current was relatively suppressed, and uniform current flowed compared to Comparative Examples 1 and 2. In particular, in the current distribution diagrams of FIGS. 12 to 15, Reference Examples 2 to 6 with a V shape and θ _V =105 to 165°, Reference Examples 9 to 12 with a C shape and θ _C =120 to 165°, and a circle In Reference Examples 13 to 25 with an arc shape and θ _S =15 to 195°, it was confirmed that the current flowed uniformly.
Due to this, as shown in Table 3 (showing that the distance d is 3 mm) and Table 4 (showing that the distance d is 6 mm), the coils of the reference examples have reduced loss, especially at high frequencies. A reduction in loss was observed at In addition, when the distance d is 6 mm, it is recognized that the loss is further reduced compared to when it is 3 mm. It was accepted that

Next, referring to the above simulation results, electric wires and coils were actually produced and evaluated.

First, using the flat-woven copper wire or the flat-woven Litz wire shown in Table 5, four types of electric wires having conductors having cross-sectional shapes shown in Table 6 were produced. More specifically, a pair of conductors each having an I-shaped cross-section was produced using a flat braided copper wire and a flat braided litz wire. One of the pair of I-shaped conductors is used as it is as an electric wire having an I-shaped conductor (Comparative Examples 3 and 4), and the other is bent to form a straight portion and a curved portion in the cross-sectional shape. (Example 1 and Example 2).

Next, using each electric wire produced above, the coil inner diameter is 85 mm, the coil outer diameter is 150 mm, the interval d between the electric wires in the winding portion is about 7 mm, and the winding portion is N = 5. , a coil was fabricated. In order to hold the coil shape, a polyolefin spacer having a shape corresponding to the cross-sectional shape of the conductor was used, and the wire was fixed to the spacer with tape. All of the coils formed of electric wires having a C-shaped cross-section were arranged in the first arrangement state O. As shown in FIG.

A direct current and an alternating current of 100 kHz and 5 MHz were applied to the four types of the produced coils, and the resistance values were measured. A digital ohmmeter (DAC-MRG-1 SOKEN) was used to measure the direct current resistance value. A vector network analyzer (nanoVNA) was used to measure the resistance value of alternating current. From the measured resistance values, obtain the resistance increase rate (the value obtained by dividing the resistance value of alternating current by the resistance value of direct current) and the ratio of the loss increase rate for a wire with a conductor having an I-shaped cross section. rice field. The results are shown in Table 7.

As shown in Table 7, it was found that the electric wire made using the flat braided litz wire is superior in the desired effect at a low frequency (100 kHz) alternating current. On the other hand, it was found that the electric wire produced using the flat braided copper wire is superior in the desired effect to the alternating current of high frequency (5 MHz).

Here, it is considered that Comparative Example 3 corresponds to Comparative Example 2 of the above simulation, and Examples 1 and 2 correspond to Reference Example 10 of the above simulation. Therefore, in order to facilitate comparison between the simulation results and the results in Table 7, the results of Comparative Example 2 and Reference Example 10 in Tables 3 and 4 were used to obtain the ratio of the loss increase rate to the I-shape. rice field. The results are shown in Table 8.

The resistance increase rate ratio in Table 7 showed the same tendency as the loss increase rate ratio in Table 8 (especially when the distance d=6 mm). Therefore, it was found that the above simulation results are accurate as an index for the production of actual wires and coils. In other words, it was found that the tendencies grasped from Tables 3 and 4 regarding the above simulation can be applied to the wires and coils actually manufactured. Therefore, the wires and coils actually manufactured based on the configuration evaluated to be excellent in reducing loss due to the skin effect and the proximity effect according to the above simulation results should have similar advantageous effects.

1: electric wire,
10: conductor, 11: upper region, 12: lower region, 13: inner peripheral edge, 14: outer peripheral edge,
15: upper end portion, 16: lower end portion, 17: corner portion, 18: straight portion, 19: curved portion,
20: insulating material,
100: coil, 110: winding part,
O: first placement state, I: second placement state

Claims (2)

A conductor having a non-circular cross-sectional shape in a plane orthogonal to the length direction,
The cross-sectional shape includes an upper region that is a region above the center in the vertical direction and is formed to bend in one of the left and right directions, and an upper region that is a region below the center in the vertical direction. and a lower region formed to bend in the same direction. 2. The cross-sectional shape according to claim 1, wherein each of said upper region and said lower region is formed in a curved line or linearly extends in a direction inclined with respect to the vertical direction. Electrical wire.

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