JP2015188033A - Thin coil and transformer - Google Patents

Abstract

A low-loss thin coil that can alleviate local current concentration and a transformer using the same.
A coil is formed by overlapping flat annular conductors 2, 2a, 2b partially opened, and the annular conductor is divided into a plurality of divided conductors 3a, 3b, 4a parallel to the outer periphery. 4b, and among the divided conductors of the annular conductors adjacent to each other in the vertical direction, the divided conductors located at symmetrical positions in the coil circumferential direction are electrically connected.
[Selection] Figure 2

Description

  The present invention relates to a thin coil and a transformer using the same.

  A transformer is a main component of an insulation type DC-DC converter which is a DC voltage conversion circuit.

  The transformer is composed of a core made of a magnetic material, and a primary coil and a secondary coil formed by winding a conducting wire around the core, and the voltage input to the primary coil is determined according to the turn ratio of the primary and secondary coils. It is converted into a different voltage on the secondary coil side.

  In recent years, transformers have been required to be thinner due to the limited installation space in consumer energy products and in-vehicle electrical components.

  On the other hand, there exists a thing which implement | achieved thinning of a transformer by comprising a coil with a flat conductor (for example, refer patent document 1).

  12A and 12B are diagrams showing the transformer structure of Patent Document 1. FIG. In FIG. 12A, the primary coil 101 and the secondary coil 102 are each configured by joining a flat annular conductor 103 having a partially opened opening in a desired number of turns and joining them in a spiral shape. The primary coil 101 and the secondary coil 102 are overlapped via an insulator 104, and the transformer 106 is configured by sandwiching them with a core 105 from above and below.

  The primary coil 101 and the secondary coil 102 thus configured can be made thinner than a coil configured by winding a round conductor having the same conductor cross-sectional area as the annular conductor 103. Thereby, the transformer 106 can be thinned.

JP-A-3-283505

  Here, when the coil current flowing through the coil constituted by the flat conductor is a high frequency of several tens (kHz) or more, the coil current is caused by the skin effect and the proximity effect, and the inner surface of the annular conductor 103 shown in FIG. 12B. Since the current path is narrowed toward the 107 side and the outer surface 108 side, the electric resistance of the coil increases.

  Furthermore, in the conventional structure, the current path on the inner surface 107 side has a shorter path length than the current path on the outer surface 108 side, so that most of the coil current is concentrated on the current path on the inner surface 107 side. As a result, the coil loss increases as compared with the case where the same amount of coil current flows through the current paths on both sides.

  An object of the present invention is to solve the above-described conventional problems, and to provide a low-loss thin coil that can alleviate local current concentration and a transformer using the same.

  In order to achieve the above object, the present invention is configured as follows.

In order to achieve the above object, according to one aspect of the present invention, a coil is formed by overlapping flat annular conductors that are partially open,
The annular conductor is composed of a plurality of divided conductors parallel to the outer periphery, and the divided conductors are divided conductors at symmetrical positions in the coil circumferential direction among the divided conductors of the annular conductors adjacent in the vertical direction. Provided is a thin coil characterized in that they are electrically connected to each other.

In order to achieve the above object, according to another aspect of the present invention, a transformer comprising a plurality of coils,
At least one coil of the plurality of coils provides a transformer configured by the thin coil described in the above aspect.

  In the present invention, the “annular” of the annular conductor includes not only a circle but also an ellipse or a polygon.

As described above, according to the above aspect of the present invention, among the current paths formed by the divided conductors, the lengths of the current paths positioned symmetrically with respect to the circumferential direction are equal, and the amount of flowing current is also equal. As a result, it is possible to provide a low-loss thin coil that can alleviate local current concentration and a transformer using the same.

The perspective view of the thin coil in a 1st embodiment of the present invention. The disassembled perspective view which shows the structure of the thin coil in 1st Embodiment of this invention. Explanatory drawing which shows the effect | action of the thin coil in 1st Embodiment of this invention. The perspective view of the thin coil (in the case of division | segmentation number m = 4) in the modification of 1st Embodiment of this invention The perspective view which shows the structure of the thin coil in the modification of 1st Embodiment of this invention (in the case of division | segmentation number m = 4). Explanatory drawing of the continuous body which forms the coil in 1st Embodiment of this invention. Explanatory drawing of the reference | standard form of the continuous body which forms the coil in 1st Embodiment of this invention Explanatory drawing of the fold line part of the thin coil in the modification of 1st Embodiment of this invention Explanatory drawing of the continuous body (regular polygon) which forms the coil in 2nd Embodiment of this invention. Explanatory drawing of the continuous body (rectangle) which forms the coil in the modification of 2nd Embodiment of this invention. Explanatory drawing of the continuous body (ellipse) which forms the coil in the modification of 2nd Embodiment of this invention Schematic diagram of a transformer using a coil in the first or second embodiment of the present invention Schematic diagram of a conventional thin transformer described in Patent Document 1 Schematic diagram of a conventional thin transformer described in Patent Document 1

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a thin coil 1 according to an embodiment of the present invention.

  The thin coil 1 is configured by laminating a large number of annular conductors 2. Here, the annular conductor of the odd number turns is 2a, and the annular conductor of the even number turns is 2b.

  The annular conductor 2 (2a, 2b) is an annular conductor flat plate having an opening 2p having an arbitrary angle, and is divided in parallel with the outer periphery to constitute divided conductors 3a, 4a, 3b, 4b. The divided conductor 3a and the divided conductor 4a are similar to each other, and the divided conductor 3b and the divided conductor 4b are similar to each other.

  As shown in FIG. 2, in the thin coil 1, the outer divided conductor 3a of the odd-numbered annular conductor 2a of the thin coil 1 is electrically connected to the inner divided conductor 4b of the even-numbered annular conductor 2b of the thin coil 1. In addition, the inner divided conductor 4a of the odd-numbered annular conductor 2a of the thin coil 1 is electrically connected to the outer divided conductor 3b of the even-numbered annular conductor 2b of the thin coil 1.

  According to such a configuration, as shown in FIG. 3, the coil current c input to one input / output end 5 of the thin coil 1 is the outer divided conductor in the annular conductor 2 a having an odd number of turns as in the current path 6. 3a, the even-numbered annular conductor 2b passes through the inner divided conductor 4b.

  Similarly, the coil current d input to the other input / output end 7 of the thin coil 1 passes through the inner divided conductor 4a in the odd-turn annular conductor 2a as in the current path 8, but the even-turn annular conductor 2a. The conductor 2b passes through the outer divided conductor 3b.

  Therefore, since the current path 6 and the current path 8 are switched symmetrically with respect to the circumferential direction of the coil 1 every time a turn is made, the path lengths are equal.

  As a result, the current does not concentrate in either one of the current paths 6 or 8, but an equivalent current flows in both the current paths 6 and 8, and the local current concentration is reduced. Can be reduced.

  In addition, although the cyclic | annular conductor 2 of FIGS. 1-3 is divided | segmented number m = 2 when it divides | segments in parallel with an outer periphery, the thin coil of this invention is not restricted to this.

  As a modification of the first embodiment, FIG. 4 shows a thin coil 10 composed of an annular conductor 9 having a division number m = 4.

  The annular conductor 9 is divided into four parallel to the outer periphery, and is composed of divided conductors 11 to 14.

  As shown in FIG. 5, the thin coil 10 is configured to be connected as follows. First, the divided conductor 11a of the odd-numbered annular conductor 9a of the thin coil 10 is electrically connected to the divided conductor 14b of the even-numbered annular conductor 9b of the thin coil 10. The divided conductor 12a of the odd-numbered annular conductor 9a of the thin coil 10 is electrically connected to the divided conductor 13b of the even-numbered annular conductor 9b of the thin coil 10. The divided conductor 13a of the odd-numbered annular conductor 9a of the thin coil 10 is electrically connected to the divided conductor 12b of the even-numbered annular conductor 9b of the thin coil 10. The divided conductor 14a of the odd-numbered annular conductor 9a of the thin coil 10 is electrically connected to the divided conductor 11b of the even-numbered annular conductor 9b of the thin coil 10.

  Therefore, in the thin coil 10, the current path formed by the split conductor 11a and the split conductor 14b and the current path formed by the split conductor 14a and the split conductor 11b are symmetrical in the coil circumferential direction each time a turn is made. In other words, the current path formed by the split conductor 12a and the split conductor 13b and the current path formed by the split conductor 13a and the split conductor 12b are switched symmetrically in the coil circumferential direction each time a turn is made.

  That is, in the thin coil according to each embodiment or modification of the present invention formed by laminating annular conductors composed of a plurality of divided conductors, the annular conductors adjacent to each other are positioned symmetrically in the coil circumferential direction. Certain divided conductors are electrically connected to each other.

  With this configuration, among the current paths formed by the divided conductors, the lengths of the current paths that are symmetrical in the circumferential direction are equal and the amount of current is also equal, so that the coil loss can be reduced.

  If the division number m is an odd number, only the current path formed by the ((m + 1) / 2) -th division conductor from the inside of the annular conductor does not have another current path to be exchanged even after the turn. The current path formed by the conductor is switched symmetrically in the circumferential direction of the coil every time a turn is made, so that a loss reduction effect can be obtained as in the case where the division number m is an even number.

Furthermore, eddy currents are generated in the annular conductor due to the leakage magnetic fluxes from the periphery, but these eddy currents are proportional to the square of the width of the conductor. Therefore, the eddy current generated in the annular conductor having the division number m is reduced to the division number m / (division number m ² ) compared with the annular conductor that is not divided, and the loss due to the eddy current can be reduced.

  On the other hand, if the number of divisions m is too large, the number of divisions m-1 is also required for the gap between the divided conductors. As a result, the divided conductor outside the annular conductor increases in its current path length and increases in electric resistance, so that the loss reduction effect is reduced.

  Furthermore, as the number m of divisions increases, the accumulated tolerance of annular conductor processing increases, and it becomes difficult to ensure shape quality.

  From the above viewpoint, it is preferable that the division number m of the annular conductor is 2 or more and 10 or less.

  The thin coil 1 according to the first embodiment of the present invention is manufactured as follows.

  6A and 6B show a continuous body 15 constituting the thin coil 1 and an annular conductor 2G which is a standard form of the continuous body 15. FIG.

  The annular conductor 2G is an annular conductor flat plate having an opening 2p having an arbitrary angle, and has an opening end 16 along the opening angle α.

  Further, the annular conductor 2G is divided into a plurality in parallel with the outer periphery, and the divided conductors 17 are arranged in parallel on the same plane at a predetermined interval.

  In the continuum 15, the second annular conductor 2G-2 is arranged point-symmetrically around the midpoint e of the opening end 16 of the first annular conductor 2G-1, and the annular conductors 2G-1 and 2G-2 are arranged. However, it has a seamless shape. By arranging the third and fourth annular conductors 2G-3 and 2G-4 in the same manner, the number of turns necessary for the thin coil 1 can be obtained.

  This continuum 15 intersects perpendicularly with a line segment ff ′ connecting the center points of adjacent annular conductors (for example, 2G-1 and 2G-2) and passes through the midpoint e of the open end 16. The thin coil 1 is formed by folding the bellows with gg ′ as a fold line.

  Note that the thin coil 1 does not have to be composed of a single continuous body 15. The thin coil 1 may be configured by electrically connecting the plurality of continuous bodies 15 or the plurality of annular conductors 2G by some means.

  The annular conductor 2G and the continuum 15 are obtained by etching or pressing a flat plate of a conductor. Further, it can be obtained by bending a rectangular wire directly into the shape of the annular conductor 2G and the continuous body 15.

  The material of the annular conductor 2G and the continuous body 15 is preferably copper, aluminum, or an alloy thereof, but oxygen-free copper having high conductivity and low loss is more preferable.

The opening angle α of the annular conductor 2G is defined by the conductor width h and the radius r of the annular conductor 2G.
2 × sin ⁻¹ ((h / 2) / r) (°)
It is preferably larger and 180 (°) or less.

If the opening angle is 2 × sin ⁻¹ ((h / 2) / r) (°) or less, the opening ends 16 overlap in the annular conductor 2G, and the thin coil 1 cannot be formed. . Further, if the opening angle is larger than 180 (°), more than 2n annular conductors 2G are required to obtain the number of turns n required for the thin coil 1, and the thickness increases. The benefits of are lost.

  Insulation of the thin coil 1 is ensured by sandwiching an insulator between the annular conductors 2G or by performing an insulating coating on the surfaces of the annular conductor 2G and the continuum 15 in advance.

  As the material of the insulator, nomec paper, urethane, epoxy, polyamide, or polyimide resin is preferable.

  It is preferable that the conductor thicknesses of the annular conductor 2G and the continuous body 15 are not more than twice the skin depth at the reference frequency of the coil current.

  If the conductor thickness is larger than twice the skin depth, current does not flow to the center of the annular conductor cross section due to the skin effect, and coil loss increases.

  On the other hand, when the value twice the skin depth at the reference frequency of the coil current is smaller than 0.05 (mm), the conductor thickness is preferably set to 0.05 (mm).

  When the conductor thickness is smaller than 0.05 (mm), the rigidity of the annular conductor 2 and the continuous body 15 is lowered, and the workability is deteriorated.

The conductor cross-sectional area of the annular conductor 2G and the continuum 15 has a current density value of 3 to 20 (A / mm ² ) obtained by dividing the current value flowing through the thin coil 1 by the total value of the conductor cross-sectional areas of the divided conductors 17. It is preferable to be within the range.

When the current density is smaller than 3 (A / mm ² ), depending on the coil current value and the above-described conductor thickness, the conductor widths of the annular conductor 2G and the continuum 15 become very large, and processing becomes difficult.

On the other hand, if the current density is greater than 20 (A / mm ² ), the thin coil 1 becomes hot due to heat generation, which may cause fire or smoke.

  A groove may be processed in a line segment g-g ′ portion that is a folding line. FIG. 7 shows an enlarged cross-sectional view of a thin coil fold line portion in a modification of the first embodiment of the present invention. The groove 18 is processed on the side that becomes a peak or a valley when bent. By processing the groove 18, the bending accuracy of the continuous body 15 is improved, and the shape quality can be improved.

  The processing dimension of the groove 18 is easier to bend as the depth i is deeper and the width j is wider. However, as the depth i is deeper, the conductor cross-sectional area of the grooved portion is reduced and loss is increased. Therefore, the depth i is desirably 60% or less of the conductor thickness k of the continuum 2.

  Furthermore, as the width j is wider, the bending accuracy of the continuous body 15 is lowered, and the shape quality of the thin coil 1 is deteriorated. Therefore, the width j is preferably about 1 to 5 times the depth i.

  The processed shape of the groove 18 is not limited to the quadrangle shown in FIG. 7, but may be a triangle or a circle.

  In the first embodiment, the shape of the annular conductors 2 and 2G has been described as a circle, but may be a square, a rectangle, or an ellipse.

  As 2nd Embodiment of this invention, the continuous body 15 which comprises a square, a rectangle, or an elliptical coil is shown in FIGS. 8-10, respectively.

  Hereinafter, as a second embodiment of the present invention and its modifications, the continuum 15H and the annular conductor 2H that form a square, rectangular, or elliptical thin coil are different from the case of forming a circular thin coil. explain. Each of these coils also has a divided conductor divided into a plurality of pieces in parallel with the outer periphery.

(Square coil)
As a second embodiment, a square coil continuum 15H shown in FIG. 8 is formed by connecting an annular conductor 2H opened at an opening angle β of 90 (°) or 180 (°) from the apex position of a square. It is formed.

(Rectangular coil)
As a modification of the second embodiment, a rectangular coil continuum 15J shown in FIG. 9 is formed by alternately connecting an annular conductor 2c having a rectangular long side opened and an annular conductor 2d having a rectangular short side opened. Formed with.

(Oval coil)
As a modification of the second embodiment, an elliptical coil continuum 15K shown in FIG. 10 includes an elliptical annular conductor 2e opened at an opening angle of γ and an opening end 16a of the annular conductor 2e ( 180- [gamma]) ([deg.]) Are formed by alternately connecting elliptical annular conductors 2f having open ends 16b at positions shifted from each other.

  FIG. 11 shows a transformer 19 using the thin coil of the first or second embodiment. The primary coil 20 and the secondary coil 21 respectively configured by the thin coils of the first or second embodiment of the present invention are overlapped via a bobbin 22 and further sandwiched from above and below by a core 23 made of a magnetic material. It has a structure. That is, both the primary coil 20 and the secondary coil 21 are respectively configured by the thin coils of the first or second embodiment.

  The material of the bobbin 22 is preferably a thermoplastic resin such as ABS, PGT, PBT, or PPS, or a thermosetting resin such as phenol or epoxy.

  The transformer 19 may comprise at least one of the primary coil 20 and the secondary coil 21 with the thin coil of the first or second embodiment.

  It is preferable that the primary coil 20 and the secondary coil 21 have the same shape as the main shaft cross-sectional shape l of the core 23 so as to minimize the current path length in order to suppress loss.

  In addition, it can be made to show the effect which each has by combining arbitrary embodiment or modification of the said various embodiment or modification suitably.

  The thin coil of the present invention can be applied as a coil for an inductor and a reactor in addition to a transformer. A DC / DC inverter and an AC / DC inverter for a power supply system in a wide range of fields such as automobiles, environment, housing, and infrastructure. It can be used as a magnetic component.

1, 10 Thin coil 2, 2a, 2b, 2c, 2d, 2e, 2G, 2G, 2G-1 to 2G-4, 2H, 9, 9a, 9b annular conductor 2p opening 3a, 3b outer divided conductor 4a, 4b Inner divided conductors 5, 7 Input / output ends 6, 8 Current paths 11, 11a, 11b, 12, 12a, 12b,
13, 13a, 13b, 14, 14a, 14b, 17 Split conductors 15, 15H, 15J, 15K Continuous body 16, 16a, 16b Open end 18 Groove 19 Transformer 20 Primary coil 21 Secondary coil 22 Bobbin 23 Core 101 Primary coil 102 Secondary coil 103 Annular conductor 104 Insulator 105 Core 106 Transformer 107 Inner side 108 Outer side

Claims (4)

It is a coil formed by overlapping flat annular conductors that are partially open,
The annular conductor is composed of a plurality of divided conductors parallel to the outer periphery, and the divided conductors are divided conductors at symmetrical positions in the coil circumferential direction among the divided conductors of the annular conductors adjacent in the vertical direction. A thin coil characterized in that they are electrically connected to each other.   The thin coil according to claim 1, wherein the annular conductor is formed of an annular conductor that opens at an opening angle of 180 (°) or less.   The thin coil according to claim 1, wherein the thin coil is formed by accordion-folding a continuous body in which a plurality of annular conductors partially opened are continuously connected. A transformer comprising a plurality of coils,
The at least 1 coil of these coils is a transformer comprised with the thin coil as described in any one of Claims 1-3.

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