JP2021108311A - Coil structure of coil unit and transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a leakage flux penetrating a gap of a planar coil. A coil unit includes a first planar coil in which a flat plate-shaped first conductor 11 is arranged in an annular shape and a second planar coil in which a flat plate-shaped second conductor 14 is arranged in an annular shape. , Has a coil structure laminated in a direction parallel to the coil axis. When viewed from a direction parallel to the coil shaft, the area of the first gap 12 that does not overlap with the second gap 15 is wider than the area of the first gap 12 that overlaps with the second gap 15. The first gap 12 is a portion where the first conductor 11 is not formed when the first planar coil is viewed from a direction parallel to the coil axis. The second gap 15 is a portion where the second conductor 14 is not formed when the second planar coil is viewed from a direction parallel to the coil axis. [Selection diagram] FIG. 1C

Description

The present invention relates to a coil structure of a coil unit and a transformer using the coil unit.

Conventionally, a laminated transformer using a primary coil and a secondary coil in which a plurality of coil layers composed of a conductive layer formed in an annular planar shape that is partially open are laminated in the vertical direction via an insulator layer has been known. (See Patent Document 1 and Patent Document 2).

Japanese Patent No. 618803 Patent No. 3489553

In the coil layer described in the above document, the annular conductive layer is formed only for one turn, and in order to obtain the required number of turns as a coil, the number of coil layers to be laminated is increased or one coil is used. It is necessary to increase the number of turns of the annular conductive layer in the layer.

When the number of coil layers to be laminated is increased, there arises a problem that the transformer becomes large in the stacking direction of the coil layers. Instead, increasing the number of turns of the annular conductive layer raises the following different challenges:

That is, when the number of turns of the annular conductive layer is increased to two or more turns, a gap is generated between the conductive layers constituting one coil layer. When the gap between the conductive layers is located at the same location between the two coils laminated via the insulator layer when viewed from the stacking direction, a closed loop of magnetic flux penetrating this gap is generated, and this closed loop Becomes a leakage flux, which causes a problem that the inductance of the coil is lowered.

The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the leakage flux penetrating the gap of the planar coil.

In order to solve the above-mentioned problems, the coil unit according to one aspect of the present invention has a first planar coil in which a flat plate-shaped first conductor is arranged in an annular shape and a flat plate-shaped second conductor in an annular shape. The arranged second planar coil has a coil structure in which the coil structure is laminated in a direction parallel to the coil axis. When viewed from a direction parallel to the coil shaft, the area of the first gap that does not overlap the second gap is wider than the area of the first gap that overlaps the second gap. The first gap is a portion where the first conductor is not formed when the first planar coil is viewed from a direction parallel to the coil axis. The second gap is a portion where the second conductor is not formed when the second planar coil is viewed from a direction parallel to the coil axis.

According to the present invention, it is possible to reduce the leakage flux penetrating the first gap and the second gap.

FIG. 1A is a plan view showing a first main surface (surface) of the coil unit in the coil structure of the coil unit 10 according to the first embodiment. FIG. 1B is a plan view showing a second main surface (back surface) of the coil structure of the coil unit 10 according to the first embodiment, which faces the first main surface (front surface) of the coil unit. FIG. 1C is a cross-sectional view showing a cross-sectional structure of the coil structure of the coil unit 10 according to the first embodiment _{along the A 1-} A _{2 cut surface shown in FIGS. 1A and 1B.} FIG. 2A is a cross-sectional view showing an example of a closed loop 21 of magnetic flux formed when a current is passed through the coil units 10 shown in FIGS. 1A to 1C. FIG. 2B shows a cross-sectional structure of the coil unit according to the comparative example, and is a cross-sectional view showing an example of closed loops 61a and 61b of magnetic flux formed when a current is passed through the coil unit according to the comparative example. FIG. 3 is a cross-sectional view showing a modified example in which a plurality of coil units (10a to 10d) having the coil structure shown in FIGS. 1A to 1C are laminated. FIG. 4A is a perspective view showing an example of a combination of the plurality of coil units 10 and the magnetic cores (23, 24). FIG. 4B is a perspective view showing one of the magnetic material pieces 23 constituting the magnetic material cores (23, 24) of FIG. 4A. FIG. 4C is a cross-sectional view showing the structure of the magnetic core (23, 24) on the cut surface including the coil central axis along the XZ plane of FIG. 4A. FIG. 4D is a cross-sectional view showing a modified example of the magnetic core (25, 26). FIG. 5A is a perspective view showing the structure of the magnetic core (63, 64) according to the comparative example. FIG. 5B is a perspective view showing one magnetic material piece 64 constituting the magnetic material core (63, 64) of FIG. 5A. FIG. 5C is a cross-sectional view showing the structure of the magnetic core (63, 64) on the cut surface including the coil central axis of FIG. 5A. FIG. 6A is a perspective view showing an example of a combination of a plurality of coil units 10 and two pairs of magnetic cores (27 to 30). FIG. 6B is a perspective view showing one of the magnetic material pieces (27, 29) constituting the magnetic material core (27 to 30) of FIG. 6A. FIG. 6C is a perspective view showing a method of fixing the magnetic material pieces (27 to 30) using the Kapton tape 39. FIG. 6D is a cross-sectional view showing the structure of the magnetic core (27 to 30) on the cut surface including the coil central axis along the XZ plane of FIG. 6A. FIG. 6E is a cross-sectional view showing a modified example of the magnetic core (31 to 33). FIG. 7A is a plan view showing the positions of a plurality of cut surfaces A to E in the coil unit 10. FIG. 7B is a cross-sectional view showing the structure of the coil unit 10 on the cut surfaces A to E of FIG. 7A. FIG. 8A is a cross-sectional view showing a quasi-gap 55a generated when the position of the outer edge 57 of the first planar coil (51) is different from the position of the outer edge 59 of the second planar coil (54). FIG. 8B is a cross-sectional view showing a state in which the gap 52 of the first planar coil (51) having different widths and the gap 55 of the second planar coil (54) overlap each other. FIG. 9 is a cross-sectional view illustrating an example of expressing the overlap of the gaps (12, 15) by using the boundaries (35, 36) between the conductors (11, 14) and the gaps (12, 15). FIG. 10A is a perspective view showing the structural elements of the transformer according to the second embodiment decomposed in the stacking direction. FIG. 10B is a cross-sectional view showing the structure of the coil cross section of the transformer according to the second embodiment. FIG. 11A is a perspective view showing the primary coils (37a to 37d) of the full-wave rectifier transformer according to the second modification by disassembling them in the stacking direction. FIG. 11B is a perspective view showing the secondary coils (38a to 38d) of the full-wave rectifier transformer according to the second modification by disassembling them in the stacking direction. FIG. 11C is a cross-sectional view showing the structure of the coil cross section of the full-wave rectifier transformer according to the second modification. FIG. 11D is a circuit diagram showing an equivalent circuit of the full-wave rectifier transformer according to the second modification.

Next, embodiments of the present invention will be described in detail with reference to the drawings. In the description, the same items will be designated by the same reference numerals and duplicate description will be omitted.

(First Embodiment)
The coil structure of the coil unit 10 according to the first embodiment will be described with reference to FIGS. 1A, 1B and 1C. 1A shows the first main surface (front surface) of the coil unit 10, FIG. 1B shows the second main surface (back surface) facing the first main surface (front surface) of the coil unit 10, and FIG. 1C shows FIG. 1A. and shows a cross sectional structure taken along the _a 1 -A ₂ cut surface shown in FIG. 1B.

In the coil structure of the coil unit 10 according to the first embodiment, the first planar coil (11) in which the flat plate-shaped first conductor 11 is arranged in an annular shape and the flat plate-shaped second conductor 14 are annularly arranged. The arranged second planar coil (14) has a coil structure in which the arranged second planar coil (14) is laminated in a direction parallel to the coil axis and electrically connected to each other. The number of turns of the first planar coil (11) is 2 or more, and the number of turns of the second planar coil (14) is 1 or 2 or more.

The portion where the first conductor 11 is not formed when the first planar coil (11) is viewed from a direction parallel to the coil axis is referred to as a "first gap 12". The portion where the second conductor 14 is not formed when the second planar coil (14) is viewed from a direction parallel to the coil axis is referred to as a “second gap 15”. When viewed from a direction parallel to the coil shaft, the area of the first gap 12 that does not overlap with the second gap 15 is wider than the area of the first gap 12 that overlaps with the second gap 15.

The coil unit 10 includes a first conductor 11, a second conductor 11, and an insulating substrate 20 arranged between the first conductor 11 and the second conductor 14. The first conductor 11, the second conductor 11, and the insulating substrate 20 each form a layer, and are laminated and adhered in a direction parallel to the coil axis. The first conductor 11 and the second conductor 14 are made of, for example, copper, and the insulating substrate 20 is a resin substrate. It can be manufactured by using semiconductor manufacturing techniques such as a planar treatment, a patterning treatment, and an etching treatment.

As shown in FIG. 1A, the number of turns of the first planar coil (11) is 3 turns, which is an example of 2 turns or more. As shown in FIG. 1B, the number of turns of the second planar coil (14) is one turn or two turns, which is an example of two or more turns. A first gap 12 is formed between the adjacent first conductors 11 in the first planar coil, and the adjacent first conductors 11 are electrically connected to each other by the first gap 12. It is insulated. A second gap 15 is formed between the adjacent second conductors 14, and the adjacent second conductors 14 are electrically insulated from each other by the second gap 15.

The outer peripheral end of the first conductor 11 forms a terminal 11a for external connection, and the outer peripheral end of the second conductor 14 forms a terminal 14a for external connection. The inner peripheral end of the first conductor 11 and the inner peripheral end of the second conductor 14 are electrically connected by a conductive plug electrode 13 penetrating the insulating substrate 20. There is. That is, the first planar coil (11) and the second planar coil (14) are electrically connected to each other by the plug electrode 13.

As shown in FIG. 1A, the first conductor 11 is wired clockwise from the outer peripheral side end portion to the inner peripheral side end portion. On the other hand, as shown in FIG. 1B, the second conductor 14 is wired clockwise from the outer peripheral side end portion to the inner peripheral side end portion. Therefore, the coil unit as a whole is wired clockwise from the terminal 11a to the terminal 14a in the plane shown in FIG. 1A and counterclockwise in the plane shown in FIG. 1B, resulting in a total of 5 turns. It forms a coil to have.

The "flat plate" in the flat plate-shaped first conductor 11 and the flat plate-shaped second conductor 14 is the cross-sectional structure of the conductors (11, 14) shown in FIG. 1C in the direction perpendicular to the coil axis. It means that the length (width) of the conductors (11, 14) is longer than the length (thickness) of the conductors (11, 14) in the direction parallel to the coil axis. For example, a conductor having a circular cross section is excluded from the flat conductors (11, 14).

The "annular" in "arranged flat conductors (11, 14) in an annular shape" includes a new circle, an ellipse, a square shape, and various planar shapes, and is a plane of a winding that is partially released. It means a shape (FIG. 1A, FIG. 1B).

In the examples shown in FIGS. 1A to 1C, the shapes and positions of the inner edge 16 and the outer edge 17 of the first planar coil (11) are the shapes and positions of the inner edge 18 and the outer edge 19 of the second planar coil (14). , And the shape and position of the inner and outer edges of the insulating substrate, respectively. However, these shapes and positions may be different or offset.

Further, an example is shown in which the number of turns of the first planar coil (11) is 3 and the number of turns of the second planar coil (14) is 2, but these are only examples. As long as the number of turns of the first planar coil (11) is 2 or more and the number of turns of the second planar coil (14) is 1 or 2 or more, other turns may be used. ..

The case where the length (width) of the first gap 12 and the second gap 15 in the direction perpendicular to the coil axis is uniform is shown. However, the width of the first gap 12 and the width of the second gap 15 may be different. The widths of the first gap 12 and the second gap 15 may be non-uniform.

In FIGS. 1A and 1B, of the first gap 12 from the inner peripheral end to the outer peripheral end of the first conductor 11 when viewed from the direction perpendicular to the paper surface, that is, the direction parallel to the coil axis. The area of the first gap 12 that does not overlap with the second gap 15 is larger than the area of the first gap 12 that overlaps with the second gap 15. As a result, as shown in FIG. 2B, the generation of the closed loops 61a and 61b of the magnetic flux penetrating the first gap 12 and the second gap 15 is suppressed. Then, as shown in FIG. 2A, the generation of the closed loop 21 of the magnetic flux including the inner edge 16 and the outer edge 17 of the first planar coil (11) and the inner edge 18 and the outer edge 19 of the second planar coil (14) is generated. Can be promoted.

FIG. 2B is a cross-sectional view showing a cross-sectional structure of the coil unit according to the comparative example. The first planar coil (51) on the front surface side and the second planar coil (54) on the back surface side are laminated via the insulating substrate 60. The gap 52 of the first planar coil (51) and the gap 55 of the second planar coil (54) overlap when viewed from a direction parallel to the coil axis. Therefore, when a current is passed through the coil unit according to the comparative example, closed loops 61a and 61b of magnetic flux penetrating the first gap 12 and the second gap 15 are generated. On the other hand, as shown in FIG. 2A, the first gap 12 and the second gap 15 according to the first embodiment do not overlap when viewed from a direction parallel to the coil axis. Therefore, the magnetic flux penetrating the first gap 12 and the second gap 15 is less likely to be generated, and more closed loops of magnetic flux are likely to be generated between the inner circumference and the outer circumference of the coil unit.

(Example of stacking a plurality of coil units 10a to 10d)
As shown in FIG. 3, a plurality of coil units having the coil structure shown in FIGS. 1A to 1C may be laminated. The plurality of coil units (10a to 10d) are laminated in a direction parallel to the coil axis via insulating paper (insulating paper 34). The front and back surfaces of all the coil units (10a to 10d) are arranged in the same direction. When viewed from the direction parallel to the coil axis, the positions of the inner and outer circumferences of all the coil units (10a to 10d) are the same.

The terminals 11a of the coil unit (10a to 10d) are electrically connected to the terminals 14a of other coil units (10a to 10d) adjacent to each other in the stacking direction. That is, the coil units (10a to 10d) are connected in series. For example, when four coil units (10a to 10d) are laminated and directly connected, a coil having a total of 20 turns can be formed. Of course, the coil units (10a to 10d) may be connected in parallel.

As shown in FIG. 3, not only inside each coil unit (10a to 10d), but also between two coil units (10a to 10d) adjacent to each other in the stacking direction, the first gap 12 and the second gap 12 and the second. The overlap with the gap 15 can be suppressed. Specifically, the second gap 15 of the coil unit 10a and the second gap 15 of the coil unit 10a do not overlap when viewed from a direction parallel to the coil axis. In this way, even between two adjacent coil units (10a to 10d), the area of the first gap 12 that does not overlap with the second gap 15 is the area of the first gap 12 that overlaps with the second gap 15. It can be larger than the area. The generation of leakage flux can be suppressed as a whole coil composed of a plurality of coil units (10a to 10d).

(Multilayer coil with magnetic core)
Further, as shown in FIGS. 4A to 4D, the inner circumference of the plurality of laminated coil units (10) is penetrated in the direction parallel to the coil axis, and the inner circumference and the outer circumference of the inner circumference of the coil unit (10) are penetrated. Cores (23, 24) made of a magnetic material forming a closed magnetic path may be further arranged between the outsides of the cores. The core (23, 24) comprises two pieces of magnetic material (23, 24) that are in surface contact with only the two surfaces (23a, 23b). In the example shown in FIGS. 4A to 4C, the two magnetic material pieces (23, 24) are divided in the direction parallel to the coil axis, and the inside of the coil unit (10) and the inside of the inner circumference and the outside of the outer circumference are respectively. It has mating surfaces (23a, 23b), respectively. FIG. 4D shows two pieces of magnetic material (25, 26) divided in the direction perpendicular to the coil axis. In each example, the two pieces of magnetic material are in contact with each other only at the two mating surfaces. As a result, it is possible to suppress the generation of voids between the mating surfaces.

On the other hand, FIGS. 5A to 5C show the core structure according to the comparative example. The core according to the comparative example penetrates the inside of the inner circumference of the plurality of laminated coil units (50) in a direction parallel to the coil axis, and is between the inside of the coil unit (50) and the inside of the inner circumference and the outside of the outer circumference. A closed magnetic path is formed in the coil shaft, and two magnetic material pieces (63, 64) divided in a direction parallel to the coil axis are provided. The two magnetic material pieces (63, 64) have a total of three mating surfaces (64a, 64b, 64c) at one location inside the coil unit (50) and inside the inner circumference and at two locations outside the outer circumference. .. When the mating surfaces of the magnetic material pieces constituting the core are three or more, voids are generated in at least one mating surface of the three due to dimensional variation during manufacturing of the magnetic material pieces. In the example of FIG. 5C, a gap is formed between the mating surface 63c of the magnetic piece 63 and the mating surface 64c of the magnetic piece 64. Since the core is designed on the assumption that there are no voids, the magnetic resistance is small, and even a small void has a large increase rate of the magnetic resistance, so that the sensitivity of the magnetic resistance to dimensional variation is high. In the present embodiment, the generation of voids can be reduced by reducing the number of mating surfaces of the pair of magnetic material pieces (23 to 26) to two or less.

Further, in the examples of FIGS. 4A to 4D, an example of a core composed of a pair of magnetic material pieces (23 to 26) is shown, but as shown in FIGS. 6A to 6E, two pairs of magnetic material pieces (27) are shown. ~ 30) Or a core composed of three or more pairs of magnetic material pieces is also applicable. The core shown in FIGS. 6A to 6D includes a pair composed of a magnetic material piece 27 and a magnetic material piece 28, and a pair composed of a magnetic material piece 29 and a magnetic material piece 30. The magnetic material piece 27 and the magnetic material piece 28 are divided in a direction parallel to the coil axis, and have mating surfaces (27a, 27b) on the inside of the coil unit (10) and on the inside of the inner circumference and the outside of the outer circumference, respectively. The magnetic material piece 27 and the magnetic material piece 28 are in surface contact with each other only on two surfaces (27a and 27b). As a result, it is possible to suppress the generation of voids between the mating surfaces. Since the magnetic material piece 29 and the magnetic material piece 30 also have the same structure as the magnetic material piece 27 and the magnetic material piece 28, the description thereof will be omitted. In FIG. 6E, two magnetic material pieces (31, 32) divided in a direction parallel to the coil axis and one magnetic material piece 33 in surface contact with each of the magnetic material pieces (31, 32) are combined. Shows the core. In the core of FIG. 6E, each magnetic material piece (31 to 33) is in surface contact with only two surfaces. As a result, it is possible to suppress the generation of voids between the mating surfaces. By using two pairs of magnetic material pieces (27 to 30) or three or more pairs of magnetic material pieces, the number of mating surfaces per pair of magnetic material pieces is maintained at 2 or less, and the coil unit 10 is exposed. It can be more suppressed. That is, a larger region of the coil unit 10 can be accommodated in the closed magnetic path of the core. Therefore, the leakage flux is less likely to occur, and the thickness of the closed magnetic path connecting the inner circumference and the outer circumference of the coil can be increased as compared with the example of FIG.

As shown in FIG. 6C, for example, by wrapping the Kapton tape 39 around the outer periphery of the magnetic material pieces (27 to 30), the magnetic material pieces can be fixed in a bonded state. Applying an adhesive to the mating surfaces of the magnetic pieces (27 to 30) is equivalent to providing a gap in the closed magnetic path, so it should be avoided as much as possible. If the outer circumference of the core is fixed with the Kapton tape 39, the magnetic material pieces (27 to 30) can be fixed without the intervention of a void factor (adhesive) in the closed magnetic path.

The two magnetic material pieces (23, 24) shown in FIGS. 4A to 4C and the four magnetic material pieces (27 to 30) shown in FIGS. 6A to 6D each have the same shape. Therefore, since the magnetic material piece can be manufactured with the same mold, the manufacturing cost can be reduced.

(First modification: An example in which the width of the conductor is non-uniform)
The case where the length (width) of the first conductor 11 and the second conductor 14 shown in FIG. 1C in the direction perpendicular to the coil axis is uniform is shown. However, the widths of the first conductor 11 and the second conductor 14 may be non-uniform in the first conductor 11 and the second conductor 14.

Each fractional view of FIG. 7B shows the cross-sectional structure of the coil unit 10 on the cut surfaces A to E of FIG. 7A. As shown in FIG. 7B, the widths of the first conductor 11 and the second conductor 14 differ depending on the position of the cut surface. When viewed from a direction parallel to the coil shaft, the first gap 12 and the second gap 15 do not overlap on the four cut surfaces (A, B, D, E) out of the five cut surfaces. However, on the remaining one cut surface (C), the first gap 12 and the second gap 15 overlap.

The number of turns of the first planar coil (11) is three. The number of turns of the second planar coil (14) is three. The length (width) of the first gap 12 and the second gap 15 in the direction perpendicular to the coil axis is uniform. In this way, the first planar coil (11) and the second planar coil (14) may have the same number of turns or different numbers of turns. That is, the number of turns of the planar coil on the front and back surfaces can be arbitrarily set.

Even if the number of turns of the first planar coil (11) and the number of turns of the second planar coil (14) are the same, the width of at least one of the first conductor 11 and the second conductor 14 By making the position variable, the positions can be shifted so that the first gap 12 and the second gap 15 do not overlap. Therefore, when viewed from a direction parallel to the coil shaft, the area of the first gap 12 that does not overlap with the second gap 15 is made wider than the area of the first gap 12 that overlaps with the second gap 15. Can be done.

(Definition of gap)
In the "gap" in the embodiment, when the number of turns of the planar coil is 2 or more, as shown in FIG. 1C, the conductors (11, 14) adjacent to each of the planar coils in the direction perpendicular to the coil axis. ) Are included (12, 15). The "gap" in the embodiment includes not only the gap (12, 15) but also the portion 55a (hereinafter, referred to as "quasi-gap 55a") corresponding to the gap shown below.

For example, as shown in FIG. 8A, the position of the outer edge 57 of the first planar coil (51) is different from the position of the outer edge 59 of the second planar coil (54) when viewed in the direction parallel to the coil axis. In this case, a quasi-gap 55a is generated. The portion from the outer edge 57 to the outer edge 59 is the quasi-gap 55a. When the outer edge 59 of the second planar coil (54) is located inside the outer edge 57 of the first planar coil (51), the portion from the outer edge 57 to the outer edge 59 is the second planar. It is defined as a quasi-gap 55a of the mold coil (54).

As shown in FIG. 8A, when the quasi-gap 55a of the second planar coil (54) and the gap 52 of the first planar coil (51) overlap, the gap 52 of the first planar coil (51) A closed loop 61c of magnetic flux penetrating the coil is generated. Therefore, when the positions of the outer edges (57, 59) of the planar coil when viewed in the direction parallel to the coil axis are different, the portion from the outer edge 57 to the outer edge 59 is defined as a quasi-gap 55a, and the conductor (11). , 14) It is desirable to treat them in the same way as the gaps (12, 15) between them. Here, as an example, the case where the positions of the outer edges (57, 59) are different is illustrated, but when the positions of the inner edges (56, 58) are different, the quasi-gap 55a is similarly defined and treated in the same manner as the gap. Is desirable.

(What is "overlapping gaps")
"Overlapping gaps" means that at least a part of the gaps overlap. For example, as shown in FIG. 8B, the width of the gap 52 of the first planar coil (51) is wider than the width of the gap 55 of the second planar coil (54). A part of the gap 52 of the first planar coil (51) overlaps with the gap 55 of the second planar coil (54). Therefore, a closed loop 61d of magnetic flux penetrating the gap 52 and the gap 55 can be generated. Therefore, in this case as well, it can be said that the gap 52 and the gap 55 overlap.

On the contrary, when the width of the first gap 12 is equal to the width of the second gap 15, "the gaps overlap" with the conductors (11, 14) and the gap (12, 15), as shown in FIG. ) And the boundary (35, 36) can be used for expression. The "boundary 35" is a boundary between the first conductor 11 and the first gap 12, and is a boundary on the inner peripheral side or the outer peripheral side of the coil unit 10. On the other hand, the boundary 36 is a boundary between the second conductor 14 and the second gap 15, and is a boundary on the inner peripheral side or the outer peripheral side of the coil unit 10. When the boundary 35 is separated from the boundary 36 by the width of the first gap 12 or more when viewed from the direction parallel to the coil axis, it can be said that the first gap 12 and the second gap 15 do not overlap.

Therefore, when the widths of the first gap 12 and the second gap 15 are equal to each other, the boundary line 35 which is separated from the boundary line 36 by the width of the first gap 12 or more when viewed from the direction parallel to the coil axis. Is longer than the length of the boundary line 35 approaching less than the width of the first gap from the boundary line 36.

As described above, according to the first embodiment, the following effects can be obtained.

The coil unit 10 includes a first planar coil (11) in which a flat plate-shaped first conductor 11 is arranged in an annular shape and a second planar coil (11) in which a flat plate-shaped second conductor 14 is arranged in an annular shape. 14) have a coil structure that is laminated in a direction parallel to the coil axis and electrically connected to each other. The number of turns of the first planar coil (11) is 2 or more, and the number of turns of the second planar coil (14) is 1 or 2 or more. When viewed from a direction parallel to the coil axis, the first planar type coil (14) does not overlap with the portion of the second planar coil (14) where the second conductor 14 is not formed (second gap 15). The area of the portion of the coil (11) where the first conductor 11 is not formed (first gap 12) is larger than the area of the first gap 12 that overlaps with the second gap 15. Of the area of the first gap 12, the area that does not overlap with the second gap 15 is wider than the area that overlaps with the second gap 15. Therefore, the generation of the leakage flux penetrating the first gap 12 and the second gap 15 is suppressed, and a closed loop is formed between the innermost diameter (16, 18) and the outermost diameter (17, 19) of the coil unit 10. The magnetic flux generated can be increased. Therefore, the leakage inductance can be reduced and the self-inductance of the coil unit 10 can be improved.

The width of the first conductor 11 and the second conductor 14 in the direction perpendicular to the coil axis is uniform, and the number of turns of the first planar coil (11) is the same as the number of turns of the second planar coil. Differently, at least one of the first planar coil (11) and the second planar coil (14) has an odd number of turns. By satisfying these conditions, the area of the first gap 12 that does not overlap with the second gap 15 can be made wider than the area of the first gap 12 that overlaps with the second gap 15.

The width of the first conductor 11 and the second conductor 14 in the direction perpendicular to at least one coil axis continuously fluctuates. Thereby, the positions of the gaps (12, 15) when viewed from the direction parallel to the coil axis can be freely arranged. Therefore, by changing the width of the conductors (11, 14), the area of the first gap 12 that does not overlap with the second gap 15 can be easily changed to the area of the first gap 12 that overlaps with the second gap 15. It can be larger than the area. Further, even if the number of turns of the first planar coil (11) is made to match the number of turns of the second planar coil, the overlap between the second gap 15 and the first gap 12 can be avoided, so that the front and back surfaces thereof. The number of turns of the planar coil (11, 14) can be arbitrarily set.

The widths of the first gap 12 and the second gap 15 are equal to each other. As shown in FIG. 9, the length of the boundary line 35, which is separated from the boundary line 36 by the width of the first gap 12 or more when viewed from the direction parallel to the coil axis, is the length of the boundary line 35 from the boundary line 36 to the first gap. It is longer than the length of border 35, which is approaching less than 12 widths. When the width of the gap is uniform, the overlap of the gap (12, 15) is specified by defining the overlap of the boundary line (35, 36) between the conductor (11, 14) and the gap (12, 15). can do.

The coil unit 10 penetrates the coil shafts of the first planar coil (11) and the second planar coil (14), and is between the inner circumference of the coil (16, 18) and the outer circumference of the coil (17, 19). It is provided with a core in which a plurality of magnetic material pieces (23 to 30) are joined so as to form a closed magnetic path. The magnetic pieces (23 to 30) are joined at two or less joining surfaces. As a result, it is possible to suppress the generation of voids between the mating surfaces.

(Second Embodiment)
The second embodiment includes a plurality of primary coils (37a to 37d) and a plurality of secondary coils (38a to 38d) having the coil structure shown in the first embodiment with reference to FIGS. 10A and 10B. The transformer will be described. Each of the plurality of primary coils (37a to 37d) and the plurality of secondary coils (38a to 38d) comprises the coil unit 10 shown in FIGS. 1A to 1C. That is, the plurality of primary coils (37a to 37d) and the plurality of secondary coils (38a to 38d) all have the same structure.

As shown in FIGS. 10A and 10B, the primary coils (37a to 37d) and the secondary coils (38a to 38d) are alternately laminated in a direction parallel to the coil axis (Z direction). The front and back surfaces of all the primary coils (37a to 37d) and the secondary coils (38a to 38d) are arranged in the same direction. Insulating paper (insulating paper 34) is inserted between the primary coils (37a to 37d) and the secondary coils (38a to 38d) adjacent to each other in the stacking direction. Adjacent primary coils (37a to 37d) and secondary coils (38a to 38d) are electrically insulated by the insulating paper 34.

The terminals 11a of the primary coils (37a to 37d) are electrically connected to the terminals 14a of the other primary coils (37a to 37d) adjacent in the stacking direction via the secondary coils (38a to 38d). .. That is, the primary coils (37a to 37d) are connected in series. For example, when four primary coils (37a to 37d) are laminated and directly connected, a primary coil with a total of 20 turns can be formed. Of course, the primary coils (37a to 37d) may be connected in parallel with each other.

Similarly, the terminals 11a of the secondary coils (38a to 38d) are electrically connected to the terminals 14a of the other secondary coils (38a to 38d) adjacent in the stacking direction via the primary coils (37a to 37d). It is connected. That is, the secondary coils (38a to 38d) are connected in series. For example, when four secondary coils (38a to 38d) are laminated and directly connected, a total of 20 turns of secondary coils can be formed. Of course, the secondary coils (38a to 38d) may be connected in parallel with each other.

Although not shown, the transformer according to the second embodiment has a plurality of transformers that form a closed magnetic path between the inner circumference and the outer circumference of all the stacked coils (37a to 37d, 38a to 38d). A core made of magnetic pieces (23 to 30) may be further provided.

Each of the primary coils (37a to 37d) and the secondary coils (38a to 38d) constituting the transformer according to the present embodiment has the coil structures shown in FIGS. 1A to 1C. That is, when viewed from a direction parallel to the coil shaft, the area of the first gap 12 that does not overlap the second gap 15 is larger than the area that overlaps the second gap 15. Therefore, the generation of the leakage flux penetrating the first gap 12 and the second gap 15 is suppressed, and a closed loop is formed between the innermost diameter (16, 18) and the outermost diameter (17, 19) of the coil unit 10. The magnetic flux generated can be increased. Therefore, the magnetic flux that forms a closed loop in the own coil without interlinking with other coils adjacent in the stacking direction decreases, and a large amount of magnetic flux can interlink with the adjacent coil. Therefore, the mutual coupling between the primary coils (37a to 37d) and the secondary coils (38a to 38d) becomes strong, and the mutual inductance of the transformer can be improved. Further, each of the primary coils (37a to 37d) and the secondary coils (38a to 38d) is composed of a printed circuit board in which planar coils are arranged on the front and back surfaces of the insulating substrate 20. Therefore, since the insulator can be made thinner than forming the primary coil or the secondary coil on the multilayer substrate, the space factor of the conductor can be improved.

The plurality of primary coils (37a to 37d) and the secondary coils (38a to 38d) all have the same structure. Since the primary coils (37a to 37d) and the secondary coils (38a to 38d) can be manufactured with one type of mold, the manufacturing cost can be suppressed.

(Second modification: full-wave rectifier transformer)
Each of the plurality of primary coils (37a to 37d) and the plurality of secondary coils (38a to 38d) comprises the coil unit 10 shown in FIGS. 1A to 1C. The plurality of primary coils (37a to 37d) and the plurality of secondary coils (38a to 38d) all have the same structure.
As shown in FIG. 11C, the primary coils (37a to 37d) and the secondary coils (38a to 38d) are alternately laminated in the direction parallel to the coil axis, as in FIG. 10B. As shown in FIGS. 11B and 11C, the secondary coils (38a to 38d) are laminated while alternately inverting the front and back sides. On the other hand, as shown in FIG. 11A, the front and back surfaces of all the primary coils (37a to 37d) are arranged in the same direction. Insulating paper (insulating paper 34) is inserted between the primary coils (37a to 37d) and the secondary coils (38a to 38d) adjacent to each other in the stacking direction.

The primary coils (37a to 37d) are connected in parallel with each other, and each primary coil (37a to 37d) is connected to terminals P1 and P2. One terminal of the secondary coil (38a to 38d) is connected to the terminal S3, the other terminal of the secondary coil (38a, 38c) is connected to the terminal S1, and the other terminal of the secondary coil (38b, 38d). Is connected to terminal S2.

Although not shown, the full-wave rectifying transformer according to the second modification forms a closed magnetic path between the inner circumference and the outer circumference of all the stacked coils (37a to 37d, 38a to 38d). , A core composed of a plurality of magnetic material pieces (23 to 30) may be further provided.

A full-wave rectifier circuit as shown in FIG. 11D is configured by connecting a diode to terminals S1 and S2 of a full-wave rectifier transformer composed of primary coils (37a to 37d) and secondary coils (38a to 38d). Can be done.

As described above, since the full-wave rectifier transformer can be configured by using only one type of coil unit 10, the manufacturing cost can be suppressed.

The above-described embodiment is an example of the embodiment of the present invention. Therefore, the present invention is not limited to the above-described embodiment, and even in other forms, various forms can be used depending on the design and the like as long as they do not deviate from the technical idea of the present invention. It goes without saying that it can be changed.

10, 10a, 10b, 10c, 10d Coil unit 11 1st conductor 12 1st gap 14 2nd conductor 15 2nd gap 23-33 Magnetic material pieces 35, 36 Boundary lines 37a, 37b, 37c, 37d primary coil 38a, 38b, 38c, 38d secondary coil

Claims (8)

A first planar coil in which a flat plate-shaped first conductor is arranged in an annular shape and a second planar coil in which a flat plate-shaped second conductor is arranged in an annular shape are laminated in a direction parallel to the coil axis. And in the coil structure of the coil units that are electrically connected to each other
The number of turns of the first planar coil is 2 or more, and the number of turns of the second planar coil is 1 or 2 or more.
When viewed from a direction parallel to the coil shaft, the area of the first gap that does not overlap with the second gap is wider than the area of the first gap that overlaps with the second gap.
The first gap indicates a portion where the first conductor is not formed when the first planar coil is viewed from a direction parallel to the coil axis.
The coil of the coil unit is characterized in that the second gap indicates a portion where the second conductor is not formed when the second planar coil is viewed from a direction parallel to the coil axis. Construction. The width of the first conductor and the second conductor in the direction perpendicular to the coil axis is uniform.
The number of turns of the first planar coil is different from the number of turns of the second planar coil, and the number of turns of at least one of the first planar coil and the second planar coil is odd. The coil structure of the coil unit according to claim 1, wherein the coil unit is provided. The coil structure of a coil unit according to claim 1, wherein the width of the first conductor and the width of the second conductor in a direction perpendicular to at least one coil axis varies. The widths of the first gap and the second gap are equal to each other.
The first conductor and the first conductor, which are separated from the boundary line between the second conductor and the second gap by the width of the first gap or more when viewed from a direction parallel to the coil axis. The length of the boundary line between the first conductor and the first gap is approaching less than the width of the first gap from the boundary line between the second conductor and the second gap. The coil structure of the coil unit according to any one of claims 1 to 3, wherein the length is longer than the length of the boundary line with the first gap. A core in which a plurality of magnetic material pieces are joined so as to penetrate the coil shafts of the first planar coil and the second planar coil and form a closed magnetic path between the inner circumference of the coil and the outer circumference of the coil. With
The coil structure of a coil unit according to any one of claims 1 to 4, wherein the plurality of magnetic material pieces are joined at two or less joint surfaces. A plurality of primary coils and a plurality of secondary coils each having the coil structure according to any one of claims 1 to 4 are provided.
A transformer characterized in that the primary coil and the secondary coil are alternately laminated in a direction parallel to the coil axis. The transformer according to claim 6, wherein the plurality of primary coils and the plurality of secondary coils all have the same structure. The transformer according to claim 7, wherein the primary coil or the secondary coil is laminated while alternately inverting the front and back sides.

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