Transformer

Abstract

To provide a transformer capable of reducing eddy-current loss.SOLUTION: A transformer 1 includes: a core 2 having a center leg 21 and side legs 22 extending in a vertical direction; a primary winding 3 wound in multiple layers around the center leg 21; a secondary winding 4 provided apart from the primary winding 3 in the vertical direction and wound in multiple layers around the center leg 21; and a path core 5 that forms, together with the core 2, a magnetic path for leakage flux, the path core 5 extending in a left-right direction and being provided between the primary winding 3 and the secondary winding 4. A gap G is formed in a section of the magnetic path extending from the center leg 21 through the path core 5 to the side legs 22. The primary winding 3 includes multiple layers 31 such that, the closer the layer 31 is to the gap G, the smaller a portion of that layer overlaps the gap G when viewed from the vertical direction. Similarly, the secondary winding 4 includes multiple layers 41 such that, the closer the layer 41 is to the gap G, the smaller a portion of that layer overlaps the gap G when viewed from the vertical direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a transformer. [Background technology]

[0002] There is known a transformer that includes a path core for magnetic flux leakage provided between a primary winding and a secondary winding (see, for example, Patent Document 1). In the transformer described in Patent Document 1, the path core protrudes from the central leg toward the side leg of two E-shaped cores facing each other. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 59-47722 Summary of the Invention [Problem to be solved by the invention]

[0004] In the transformer described in Patent Document 1, a gap is formed between the path core and the side legs. Among the magnetic fluxes generated by current flowing through the windings, leakage magnetic flux circulates along a path that runs from the center leg through the path core, gap, and side legs, returning to the center leg. Because magnetic flux follows the path of least resistance, the leakage magnetic flux passes closer to the windings in the gap than the extended portion of the path core. Therefore, the leakage magnetic flux may interlink with the windings, resulting in eddy current loss.

[0005] The present disclosure describes a transformer capable of reducing eddy current losses. [Means for solving the problem]

[0006] A transformer according to one aspect of the present disclosure includes a core having a central leg extending in a first direction and side legs extending in the first direction and spaced apart from the central leg in a second direction intersecting the first direction; a primary winding wound in multiple layers around the central leg; a secondary winding spaced apart from the primary winding in the first direction and wound in multiple layers around the central leg; and a path core extending in the second direction and disposed between the primary winding and the secondary winding, the path core forming a magnetic path for leakage magnetic flux together with the core. A gap is formed in the section of the magnetic path extending from the central leg through the path core to the side leg. The primary winding includes multiple primary layers, with the layer closer to the gap having a smaller overlap with the gap when viewed from the first direction. The secondary winding includes multiple secondary layers, with the layer closer to the gap having a smaller overlap with the gap when viewed from the first direction.

[0007] In this transformer, the primary layer of the primary winding closer to the gap has a smaller overlapping portion with the gap when viewed from the first direction, and the secondary layer of the secondary winding closer to the gap has a smaller overlapping portion with the gap when viewed from the first direction. Therefore, even if leakage flux passes closer to the primary winding than the extended portion of the path core in the gap, the leakage flux linking with the primary winding can be reduced. Similarly, even if leakage flux passes closer to the secondary winding than the extended portion of the path core in the gap, the leakage flux linking with the secondary winding can be reduced. As a result, eddy current loss can be reduced.

[0008] Among the multiple primary layers, the layer closer to the gap may have fewer turns, and among the multiple secondary layers, the layer closer to the gap may have fewer turns. In this case, since the primary layer closer to the gap has fewer turns of the primary winding, simply by arranging the conductive member that constitutes the primary winding at a position farther from the gap in the primary layer closer to the gap, the portion overlapping with the gap as viewed from the first direction can be reduced. Similarly, among the secondary winding, the secondary layer closer to the gap has fewer turns of the secondary winding, so simply by arranging the conductive member that constitutes the secondary winding at a position farther from the gap in the secondary layer closer to the gap, the portion overlapping with the gap as viewed from the first direction can be reduced.

[0009] The gap may include a plurality of gap portions spaced apart from one another and arranged in the second direction. In this case, the primary layers of the primary winding closer to the gap have smaller overlapping portions with the plurality of gap portions as viewed from the first direction, and the secondary layers of the secondary winding closer to the gap have smaller overlapping portions with the plurality of gap portions as viewed from the first direction. Therefore, even if leakage flux passes closer to the primary winding than the extended portion of the path core at each gap portion, the leakage flux linking with the primary winding can be reduced. Similarly, even if leakage flux passes closer to the secondary winding than the extended portion of the path core at each gap portion, the leakage flux linking with the secondary winding can be reduced. As a result, eddy current loss can be reduced.

[0010] The multiple gap portions may include a first gap portion and a second gap portion, and the length of the first gap portion in the second direction may be shorter than the length of the second gap portion in the second direction. The primary winding may be arranged farther from the second gap portion than from the first gap portion, and the secondary winding may be arranged farther from the second gap portion than from the first gap portion. The longer the length of the gap portion in the second direction, the more leakage magnetic flux passes near the winding rather than the extended portion of the path core. According to the above configuration, the primary winding and the secondary winding are arranged farther from the second gap portion, which is longer in the second direction than the first gap portion, thereby reducing leakage magnetic flux linking with each winding. As a result, eddy current loss can be reduced. [Effects of the Invention]

[0011] According to the present disclosure, eddy current loss can be reduced. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view showing a schematic configuration of a transformer according to one embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3]FIG. 3 is a diagram schematically showing paths of leakage magnetic flux in the transformer shown in FIG. [Figure 4] FIG. 4 is a diagram schematically showing the path of leakage magnetic flux in a transformer of a comparative example. [Figure 5] FIG. 5 is a cross-sectional view showing a schematic configuration of a transformer according to another embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing a schematic configuration of a transformer according to still another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] A transformer according to one embodiment will be described in detail below with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements are designated by the same reference numerals, and redundant description will be omitted. Each drawing shows an XYZ coordinate system. The Y-axis direction is a direction intersecting (e.g., perpendicular to) the X-axis direction (second direction) and the Z-axis direction (first direction). The Z-axis direction is a direction intersecting (e.g., perpendicular to) the X-axis direction and the Y-axis direction. In the following description, as an example, the X-axis direction is defined as the left-right direction (width direction), the Y-axis direction is defined as the front-back direction (depth direction), and the Z-axis direction is defined as the up-down direction (height direction). The X-axis, Y-axis, and Z-axis directions are not limited to the above directions.

[0014] A schematic configuration of a transformer according to one embodiment will be described with reference to Figures 1 and 2. Figure 1 is a perspective view showing a schematic configuration of a transformer according to one embodiment. Figure 2 is a cross-sectional view taken along line II-II in Figure 1. The transformer 1 shown in Figures 1 and 2 is a device that converts a primary voltage into a secondary voltage, and includes a core 2, a primary winding 3, a secondary winding 4, a path core 5, and a bobbin 6. Note that the bobbin 6 is not shown in Figure 2.

[0015] The core 2 is a magnetic body that forms a magnetic path. The core 2 includes a central leg 21, a pair of side legs 22, and a pair of connecting portions 23. The central leg 21 and the pair of side legs 22 each extend in the up-down direction. The central leg 21 and the pair of side legs 22 are arranged substantially parallel to each other. The pair of side legs 22 are spaced apart from the central leg 21 in the left-right direction. The central leg 21 is arranged between the pair of side legs 22 in the left-right direction. The pair of connecting portions 23 connect the pair of side legs 22 and the central leg 21. Each connecting portion 23 has a flat plate shape. One connecting portion 23 connects one end of the central leg 21 to one end of each side leg 22. The other connecting portion 23 connects the other end of the central leg 21 to the other end of each side leg 22.

[0016] In this embodiment, the core 2 is an EI core composed of an E-shaped core member 2a and an I-shaped core member 2b. A boundary B1 is formed between the core members 2a and 2b. The shape of the core 2 is not limited to an EI core, and may be an EE core or a PQ core.

[0017] The primary winding 3 and the secondary winding 4 are formed by winding a long conductive material in a spiral shape. The primary winding 3 and the secondary winding 4 are wound in multiple layers around the central leg 21. The secondary winding 4 is provided spaced apart from the primary winding 3 in the vertical direction. In this embodiment, the primary winding 3 and the secondary winding 4 are edgewise coils formed by winding a flat copper wire in the width direction of the copper wire. The conductive material forming the primary winding 3 and the secondary winding 4 is not limited to a flat copper wire. The primary winding 3 and the secondary winding 4 will be described in detail later.

[0018] The path core 5 is a magnetic material that, together with the core 2, forms a magnetic path MP (see FIG. 3) for leakage magnetic flux. The path core 5 extends in the left-right direction and is provided between the primary winding 3 and the secondary winding 4 in the up-down direction. The path core 5 is arranged so that a gap G is formed in a section S (see FIG. 3). The section S is a section of the magnetic path MP that runs from the central leg 21 through the path core 5 to the side leg 22. The gap G refers to a portion of the magnetic path MP where a magnetic material is missing. In this embodiment, the gap G is formed by an air layer or a part of the bobbin 6.

[0019] The gap G may include a plurality of gap portions spaced apart from each other and arranged in the left-right direction. In this embodiment, the gap G includes a gap portion G1 (first gap portion) and a gap portion G2 (second gap portion). The gap portion G1 is a gap portion formed between the path core 5 and the central leg 21. The gap portion G2 is a gap portion formed between the path core 5 and the side leg 22. The leakage inductance of the transformer 1 is determined according to the sum of the lengths (gap lengths) of the gaps G provided on the magnetic path MP along the magnetic path MP. Therefore, the gap lengths of the gap portions formed in the section S are determined so as to obtain a desired leakage inductance. In this embodiment, the length of the gap portion G1 in the left-right direction (gap length L1) is approximately the same as the length of the gap portion G2 in the left-right direction (gap length L2).

[0020] The bobbin 6 is a member that holds the primary winding 3 and the secondary winding 4. The bobbin 6 is made of an insulating material. Examples of insulating materials that can be used to make the bobbin 6 include resins such as plastic. The bobbin 6 electrically separates the primary winding 3 and the secondary winding 4, and also electrically separates the primary winding 3 and the secondary winding 4 from the core 2. The bobbin 6 houses the path core 5. The bobbin 6 holds the path core 5 while fixing the position of the path core 5.

[0021] Next, the primary winding 3 and the secondary winding 4 will be described in detail.

[0022] 2, each of the primary winding 3 and the secondary winding 4 is laminated with a predetermined number of turns of conductive material wound around it per layer. A layer in a winding refers to a predetermined number of turns of the conductive material, and corresponds to a layer in the cross section shown in FIG.

[0023] The primary winding 3 includes a plurality of layers 31 (primary layers). The layer 31 closer to the gap G has a smaller portion overlapping the gap G when viewed from above and below. Specifically, among the plurality of layers 31, the layer 31 closer to the gap G has fewer turns. In the example shown in FIG. 2, the layer 31 closest to the gap G has one turn, and the other layers 31 have two turns.

[0024] The conductive member of layer 31 closest to gap G is positioned so as not to overlap either gap portion G1 or gap portion G2 when viewed from the top-bottom direction. This conductive member is positioned midway between the side surface of central leg 21 and the inner surface of side leg 22 in the left-right direction, and the left-right distance between the inner peripheral edge of this conductive member and central leg 21 (the side surface of central leg 21) is substantially equal to the left-right distance between the outer peripheral edge of this conductive member and side leg 22 (the inner surface of side leg 22).

[0025] Other layer 31 includes two turns of conductive material arranged in the left-right direction, and this set of conductive material is arranged in the middle position in the left-right direction between the side surface of central leg 21 and the inner surface of side leg 22. In other words, the left-right distance between the inner peripheral edge of the conductive material located on the inside and central leg 21 (the side surface of central leg 21) is substantially equal to the left-right distance between the outer peripheral edge of the conductive material located on the outside and side leg 22 (the inner surface of side leg 22).

[0026] The secondary winding 4 includes multiple layers 41 (secondary layers). The layer 41 closer to the gap G has a smaller portion overlapping the gap G when viewed from above and below. Specifically, among the multiple layers 41, the layer 41 closer to the gap G has fewer turns. In the example shown in FIG. 2, the layer 41 closest to the gap G has one turn, and the other layers 41 have two turns.

[0027] The conductive member of layer 41 closest to gap G is positioned so as not to overlap either gap portion G1 or gap portion G2 when viewed from the top-bottom direction. This conductive member is positioned midway between the side surface of central leg 21 and the inner surface of side leg 22 in the left-right direction, and the distance in the left-right direction between the inner peripheral edge of this conductive member and central leg 21 (the side surface of central leg 21) is substantially equal to the distance in the left-right direction between the outer peripheral edge of this conductive member and side leg 22 (the inner surface of side leg 22).

[0028] Other layer 41 includes two turns of conductive material arranged in the left-right direction, and this set of conductive material is arranged in the middle position in the left-right direction between the side surface of central leg 21 and the inner surface of side leg 22. In other words, the left-right distance between the inner peripheral edge of the conductive material located on the inside and central leg 21 (the side surface of central leg 21) is substantially equal to the left-right distance between the outer peripheral edge of the conductive material located on the outside and side leg 22 (the inner surface of side leg 22).

[0029] In the transformer 1, the ratio of the total number of turns in all layers 31 to the total number of turns in all layers 41 is equal to the ratio of the primary voltage to the secondary voltage. The number of turns in each layer 31 and each layer 41 is determined within a range that satisfies this relationship.

[0030] Next, the effects of the transformer 1 will be described with reference to Figures 3 and 4. Figure 3 is a diagram schematically showing the path of leakage magnetic flux in the transformer shown in Figure 1. Figure 4 is a diagram schematically showing the path of leakage magnetic flux in a transformer of a comparative example. For ease of explanation, the ratio of the dimension in the X-axis direction to the dimension in the Z-axis direction in Figures 3 and 4 is different from that in Figure 2.

[0031] 4 differs from the transformer 1 mainly in that it includes a primary winding 103 and a secondary winding 104 instead of the primary winding 3 and the secondary winding 4. In the primary winding 103 and the secondary winding 104, a conductive member is wound in five layers with two turns per layer.

[0032] In the transformer 100, a magnetic flux is generated when a current flows through the primary winding 103. The leakage magnetic flux travels along a path (magnetic path MP) that starts at the center leg 21 of the core 2, passes through the gap G1, the path core 5, the gap G2, the side leg 22, and the connecting portion 23, and returns to the center leg 21. Because the magnetic flux travels along the path of minimum resistance, the leakage magnetic flux passes closer to the primary winding 103 than the extended portion of the path core 5 at the gap G1 and the gap G2. Therefore, the leakage magnetic flux may interlink with the primary winding 103, resulting in eddy current loss. Similarly, the leakage magnetic flux generated when a current flows through the secondary winding 104 of the transformer 100 passes closer to the secondary winding 104 than the extended portion of the path core 5 at the gap G1 and the gap G2. Therefore, the leakage magnetic flux may interlink with the secondary winding 104, resulting in eddy current loss.

[0033] On the other hand, as shown in FIG. 3 , in the transformer 1, the layer 31 of the primary winding 3 closer to the gap G has a smaller portion overlapping the gap G in a vertical direction. Specifically, in the transformer 1, the gap G includes gap portions G1 and G2 spaced apart from each other and arranged in the left-right direction. Therefore, the layer 31 of the primary winding 3 closer to the gap G has a smaller total portion overlapping the gap portions G1 and G2 in a vertical direction. More specifically, in the layer 31 closest to the gap G, the conductive member does not overlap either the gap portion G1 or the gap portion G2 in a vertical direction. Therefore, even if leakage flux generated by a current flowing through the primary winding 3 of the transformer 1 passes closer to the primary winding 3 in the gap portions G1 and G2 than the extended portion of the path core 5, the leakage flux linking with the primary winding 3 can be reduced.

[0034] Similarly, in the transformer 1, the layer 41 of the secondary winding 4 closer to the gap G has a smaller portion overlapping the gap G when viewed from above. Specifically, in the transformer 1, the layer 41 of the secondary winding 4 closer to the gap G has a smaller total portion overlapping the gaps G1 and G2 when viewed from above. More specifically, in the layer 41 closest to the gap G, the conductive member does not overlap either the gap G1 or the gap G2 when viewed from above. Therefore, even if leakage flux generated by current flowing through the secondary winding 4 of the transformer 1 passes closer to the secondary winding 4 in the gaps G1 and G2 than the extended portion of the path core 5, the leakage flux linking with the secondary winding 4 can be reduced. As a result, eddy current loss can be reduced.

[0035] More specifically, among the multiple layers 31, the number of turns is smaller the closer the layer 31 is to the gap G. Therefore, simply by arranging the conductive members of the primary winding 3 at positions away from each of the gap portions G1 and G2 in the layer 31 close to the gap G, the portion overlapping with the gap G as viewed from above can be made smaller. Similarly, among the multiple layers 41, the number of turns is smaller the closer the layer 41 is to the gap G. Therefore, simply by arranging the conductive members of the secondary winding 4 at positions away from each of the gap portions G1 and G2 in the layer 41 close to the gap G, the portion overlapping with the gap G as viewed from above can be made smaller.

[0036] Next, the schematic configuration of a transformer according to another embodiment will be described with reference to Fig. 5. Fig. 5 is a cross-sectional view showing the schematic configuration of a transformer according to another embodiment. A transformer 1A shown in Fig. 5 differs from the transformer 1 mainly in that it includes a primary winding 3A and a secondary winding 4A instead of the primary winding 3 and the secondary winding 4, and in the arrangement of the path core 5. In the transformer 1A, the path core 5 is arranged so that the gap length L1 is shorter than the gap length L2.

[0037] As with the primary winding 3, the primary winding 3A is arranged such that the layer 31 closer to the gap G has a smaller portion overlapping the gap G when viewed from above. Furthermore, the primary winding 3A is arranged so as to be farther away from gap portion G2 than from gap portion G1.

[0038] Specifically, the layer 31 closest to gap G includes one turn of conductive material, and this conductive material is positioned so as not to overlap either gap G1 or gap G2 when viewed from the top-bottom direction. The conductive material is positioned closer to gap G1 than the midpoint in the left-right direction between the side surface of central leg 21 and the inner surface of side leg 22, and farther from gap G2. In other words, the conductive material is positioned between central leg 21 and side leg 22, closer to central leg 21, and the left-right distance between the inner peripheral edge of the conductive material and central leg 21 (the side surface of central leg 21) is shorter than the left-right distance between the outer peripheral edge of the conductive material and side leg 22 (the inner surface of side leg 22).

[0039] The layer 31 second closest to gap G includes two turns of conductive material arranged in the left-right direction, and this set of conductive material is located closer to gap G1 than the midpoint in the left-right direction between the side surface of central leg 21 and the inner surface of side leg 22, and farther from gap G2. In other words, the set of conductive material is located closer to central leg 21 between central leg 21 and side leg 22, and the left-right distance between the inner peripheral edge of the conductive material located on the inside and central leg 21 (the side surface of central leg 21) is shorter than the left-right distance between the outer peripheral edge of the conductive material located on the outside and side leg 22 (the inner surface of side leg 22).

[0040] Other layer 31 includes three turns of conductive material arranged in the left-right direction, and this set of conductive material is arranged in the middle in the left-right direction between the side surface of central leg 21 and the inner surface of side leg 22. In other words, the left-right distance between the inner peripheral edge of the innermost conductive material and central leg 21 (the side surface of central leg 21) is substantially equal to the left-right distance between the outer peripheral edge of the outermost conductive material and side leg 22 (the inner surface of side leg 22).

[0041] As with the secondary winding 4, the secondary winding 4A is arranged such that the layer 41 closer to the gap G has a smaller portion overlapping the gap G when viewed from above. Furthermore, the secondary winding 4A is arranged so as to be farther away from gap portion G2 than from gap portion G1.

[0042] Specifically, layer 41 closest to gap G includes one turn of conductive material, and this conductive material is positioned so as not to overlap either gap portion G1 or gap portion G2 when viewed from the top-bottom direction. The conductive material is positioned closer to gap portion G1 than the midpoint in the left-right direction between the side surface of central leg 21 and the inner surface of side leg 22, and farther from gap portion G2. In other words, the conductive material is positioned between central leg 21 and side leg 22, closer to central leg 21, and the left-right distance between the inner peripheral edge of the conductive material and central leg 21 (the side surface of central leg 21) is shorter than the left-right distance between the outer peripheral edge of the conductive material and side leg 22 (the inner surface of side leg 22).

[0043] The layer 41 second closest to gap G includes two turns of conductive material arranged in the left-right direction, and this set of conductive material is located closer to gap G1 than the midpoint in the left-right direction between the side surface of central leg 21 and the inner surface of side leg 22, and farther from gap G2. In other words, the set of conductive material is located closer to central leg 21 between central leg 21 and side leg 22, and the left-right distance between the inner peripheral edge of the conductive material located on the inside and central leg 21 (the side surface of central leg 21) is shorter than the left-right distance between the outer peripheral edge of the conductive material located on the outside and side leg 22 (the inner surface of side leg 22).

[0044] Other layer 41 includes three turns of conductive material arranged in the left-right direction, and this set of conductive material is arranged in the middle in the left-right direction between the side surface of central leg 21 and the inner surface of side leg 22. In other words, the left-right distance between the inner peripheral edge of the innermost conductive material and central leg 21 (the side surface of central leg 21) is substantially equal to the left-right distance between the outer peripheral edge of the outermost conductive material and side leg 22 (the inner surface of side leg 22).

[0045] The transformer 1A also has the same configuration as the transformer 1, and thus has the same effects as the transformer 1.

[0046] In the transformer 1A, leakage magnetic flux, which is generated by a current flowing through the primary winding 3A, travels along a path (magnetic path MP) that starts at the center leg 21 of the core 2, passes through the gap G1, the path core 5, the gap G2, the side leg 22, and the connecting portion 23, and then returns to the center leg 21. Because magnetic flux travels along the path of minimum resistance, the leakage magnetic flux passes closer to the primary winding 3A in the gaps G1 and G2 than the extended portion of the path core 5. The longer the gap length, the more leakage magnetic flux passes closer to the primary winding 3A than the extended portion of the path core 5. Therefore, more magnetic flux passes closer to the primary winding 3A in the gap G2 than in the gap G1. In the transformer 1A, the primary winding 3A is positioned away from the gap G2, which has a longer gap length than the gap G1, thereby reducing the leakage magnetic flux interlinking with the primary winding 3A.

[0047] Similarly, in the transformer 1A, the secondary winding 4A is positioned away from the gap portion G2, which has a gap length longer than the gap portion G1. Therefore, even if leakage flux generated by a current flowing through the secondary winding 4A of the transformer 1A passes closer to the secondary winding 4A than the extended portion of the path core 5 in the gap portions G1 and G2, the leakage flux linking with the secondary winding 4A can be reduced. As a result, it is possible to reduce eddy current loss.

[0048] Next, the schematic configuration of a transformer according to yet another embodiment will be described with reference to Fig. 6. Fig. 6 is a cross-sectional view showing the schematic configuration of a transformer according to yet another embodiment. Transformer 1B shown in Fig. 6 differs from transformer 1A mainly in that it includes a core 2B, a primary winding 3B, a secondary winding 4B, and a path core 5B instead of core 2, primary winding 3A, secondary winding 4A, and path core 5.

[0049] Core 2B differs from core 2 mainly in its shape. Core 2B is an EE core composed of E-shaped core member 2c and E-shaped core member 2d. A boundary B2 is formed between core member 2c and core member 2d.

[0050] The path core 5B differs from the path core 5 mainly in its shape and arrangement. The path core 5B is connected to the core 2B. Specifically, the path core 5B is sandwiched between the central leg 21 of the core member 2c and the central leg 21 of the core member 2d, and protrudes to the left and right from the central leg 21 toward a pair of side legs 22. The path core 5B is provided between the primary winding 3B and the secondary winding 4B in the vertical direction. The path core 5B is arranged so that a gap G is formed in the section S. A boundary B3 is formed between the core member 2c and the path core 5B. A boundary B4 is formed between the core member 2d and the path core 5B.

[0051] As with the primary windings 3 and 3A, the primary winding 3B is arranged such that the layer 31 closer to the gap G has a smaller portion that overlaps with the gap G when viewed from above. Specifically, as with the primary winding 3A, the primary winding 3B has one turn of winding in the layer 31 closest to the gap G, two turns of winding in the layer 31 second closest to the gap G, and three turns of winding in the other layers 31.

[0052] As with the secondary windings 4 and 4A, the secondary winding 4B is arranged such that the layer 41 closer to the gap G has a smaller portion overlapping the gap G when viewed from above. Specifically, as with the secondary winding 4A, the number of turns in the layer 41 closest to the gap G is 1, the number of turns in the layer 41 second closest to the gap G is 2, and the number of turns in the other layers 41 is 3.

[0053] The transformer 1B also has the same configuration as the transformers 1 and 1A, and thus has the same effects as the transformers 1 and 1A.

[0054] Although the embodiments of the present disclosure have been described in detail above, the transformer according to the present disclosure is not limited to the above embodiments.

[0055] In the primary windings 3, 3A, and 3B, the number of turns of all layers 31 may be the same, and the overlapping portion with the gap G as viewed from the top-bottom direction may be adjusted by changing the arrangement of the layers 31. Similarly, in the secondary windings 4, 4A, and 4B, the number of turns of all layers 41 may be the same, and the overlapping portion with the gap G as viewed from the top-bottom direction may be adjusted by changing the arrangement of the layers 41.

[0056] A gap may be formed at a portion of boundary B1 by separating the opposing core members 2a and 2b. If the gap length (the distance between core members 2a and 2b) of the gap exceeds 0.1 mm, the number of turns in layer 31 closer to the gap may be less than the number of turns in layer 31 farther from the gap, and the number of turns in layer 41 closer to the gap may be less than the number of turns in layer 41 farther from the gap. The same applies to boundaries B2, B3, and B4 when a gap with a gap length exceeding 0.1 mm is formed.

[0057] (Addendum) [Article 1] a core having a central leg portion extending in a first direction and side legs extending in the first direction and spaced apart from the central leg portion in a second direction intersecting the first direction; a primary winding wound in multiple layers around the central leg; a secondary winding spaced apart from the primary winding in the first direction and wound in multiple layers around the central leg; a path core that forms a magnetic path of leakage magnetic flux together with the core, the path core extending in the second direction and provided between the primary winding and the secondary winding; Equipped with a gap is formed in a section of the magnetic path from the center leg through the path core to the side leg, the primary winding includes a plurality of primary layers, each of which has a smaller overlapping portion with the gap as viewed from the first direction, the closer the layer is to the gap, The secondary winding includes a plurality of secondary layers, each of which has a smaller overlap with the gap as viewed from the first direction, the closer the layer is to the gap.

[0058] [Clause 2] In the plurality of primary layers, the layers closer to the gap have fewer turns; 10. The transformer of claim 1, wherein the plurality of secondary layers have fewer turns than the layers closer to the gap.

[0059] [Article 3] The transformer of clause 1 or clause 2, wherein the gap includes a plurality of gap portions spaced apart from each other and arranged in the second direction.

[0060] [Article 4] the plurality of gap portions include a first gap portion and a second gap portion; a length of the first gap portion in the second direction is shorter than a length of the second gap portion in the second direction; the primary winding is disposed farther from the second gap portion than from the first gap portion; 4. The transformer of claim 3, wherein the secondary winding is positioned farther from the second gap portion than from the first gap portion. [Explanation of symbols]

[0061] 1, 1A, 1B... transformer, 2, 2B... core, 3, 3A, 3B... primary winding, 4, 4A, 4B... secondary winding, 5, 5B... path core, 21... center leg, 22... side leg, 31... layer (primary layer), 41... layer (secondary layer), G... gap, G1... gap portion (first gap portion), G2... gap portion (second gap portion).

Claims

1. a core having a central leg portion extending in a first direction and side legs extending in the first direction and spaced apart from the central leg portion in a second direction intersecting the first direction; a primary winding wound in multiple layers around the central leg; a secondary winding spaced apart from the primary winding in the first direction and wound in multiple layers around the central leg; a path core that forms a magnetic path for leakage magnetic flux together with the core, the path core extending in the second direction and being provided between the primary winding and the secondary winding; Equipped with a gap is formed in a section of the magnetic path from the center leg through the path core to the side leg, the primary winding includes a plurality of primary layers, each of which has a smaller overlapping portion with the gap as viewed from the first direction, the closer the layer is to the gap, The secondary winding includes a plurality of secondary layers, each of which has a smaller overlapping portion with the gap as viewed from the first direction, the closer the layer is to the gap.

2. In the plurality of primary layers, the layers closer to the gap have fewer turns; 2. The transformer of claim 1, wherein the plurality of secondary layers have fewer turns than the layers closer to the gap.

3. 3. The transformer according to claim 1, wherein the gap includes a plurality of gap portions spaced apart from each other and arranged in the second direction.

4. the plurality of gap portions include a first gap portion and a second gap portion; a length of the first gap portion in the second direction is shorter than a length of the second gap portion in the second direction; the primary winding is disposed farther from the second gap portion than from the first gap portion; The transformer according to claim 3 , wherein the secondary winding is disposed farther from the second gap portion than from the first gap portion.

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