Transformer and power converter

Abstract

To provide a transformer capable of suppressing a partial discharge while suppressing a size of a device from being increased.SOLUTION: Each transformer (100, 200, and 300) comprises: each bobbin (10 and 11); a plurality of wirings (20 and 21); and a plurality of insulation layers (30, 40, and 70). The plurality of wirings are wound to a circumference of each bobbin. The plurality of insulation layers include at least one first insulation layer (30) interposed to adjacent two wirings of the plurality of wirings. Each of at least one first insulation layer, includes: a first layer (31); a second layer (32); and a first intermediate conductor (33) that is interposed to between the first layer and the second layer, and is a floating potential.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] For example, Japanese Patent Laid-Open Publication No. 8-97053 (Patent Document 1) describes a winding device. The winding device described in Patent Document 1 has a coil bobbin, a first winding, an insulating sheet, and a second winding. The first winding is wound around the coil bobbin. The insulating sheet is wound around the first winding. The second winding is wound around the insulating sheet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-97053 Summary of the Invention [Problem to be solved by the invention]

[0004] In the winding device of Patent Document 1, defects (voids, gaps) may exist in the wound insulating sheet. Therefore, in the winding device described in Patent Document 1, partial discharge occurs according to Paschen's law when an AC voltage is applied. One possible solution to this problem is to increase the thickness of the insulating sheet. However, increasing the thickness of the insulating sheet increases the size of the device.

[0005] The present disclosure has been made in consideration of the above-described problems of the conventional technology. More specifically, the present disclosure provides a transformer that can suppress partial discharge while preventing an increase in the size of the device. [Means for solving the problem]

[0006] The transformer of the present disclosure includes a bobbin, multiple windings, and multiple insulating layers. The multiple windings are wound around the bobbin. The multiple insulating layers include at least one first insulating layer interposed between adjacent two of the multiple windings. Each of the at least one first insulating layer includes a first layer, a second layer, and a first intermediate conductor interposed between the first and second layers and set to a floating potential. [Effects of the Invention]

[0007] The transformer of the present disclosure can suppress partial discharge while preventing the device from becoming large. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a transformer 100. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is a cross-sectional view of a transformer 100A. [Figure 4] 10 is a graph showing the relationship between the thickness of the first insulating layer 30 and the partial discharge inception voltage between the primary winding 20 and the secondary winding 21. [Figure 5] 1 is a schematic diagram illustrating the effect of the transformer 100. FIG. [Figure 6] FIG. 2 is a perspective view showing a simulation model of the transformer 100. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 1 is a perspective view showing a simulation model of a transformer 100A. [Figure 9] FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. 8. [Figure 10] FIG. 2 is a cross-sectional view of a transformer 200. [Figure 11] 10 is a schematic diagram illustrating the effect of the transformer 200. FIG. [Figure 12] FIG. 3 is a cross-sectional view of a transformer 300. [Figure 13] 10 is a first schematic diagram illustrating the effect of the transformer 300. FIG. [Figure 14] FIG. 2 is a second schematic diagram illustrating the effect of the transformer 300. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present disclosure will be described with reference to the accompanying drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and redundant description will not be repeated.

[0010] Embodiment 1 The transformer according to the first embodiment will be described below. The transformer according to the first embodiment is designated as transformer 100.

[0011] (Transformer 100 configuration) The configuration of the transformer 100 will be described below.

[0012] The transformer 100 is used, for example, in a power converter. FIG. 1 is a perspective view of the transformer 100. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. As shown in FIGS. 1 and 2, the transformer 100 includes a bobbin 10, a first winding 20, a second winding 21, a first insulating layer 30, a second insulating layer 40, and a core 50.

[0013] The bobbin 10 has a cylindrical portion 11 and flange portions 12 and 13. The bobbin 10 is made of a thermoplastic resin such as polybutylene terephthalate (PBT) or a thermosetting resin such as phenolic resin. The direction in which the cylindrical portion 11 extends is defined as the axial direction. The cylindrical portion 11 has an outer peripheral surface 11a. The flange portion 12 protrudes from the outer peripheral surface 11a at one end of the cylindrical portion 11 in the axial direction. The flange portion 13 protrudes from the outer peripheral surface 11a at the other end of the cylindrical portion 11 in the axial direction. An insulating tape 60 is wound around the outer peripheral surface 11a at a position adjacent to the flange portions 12 and 13. The insulating tape 60 is wound to ensure an insulating distance between each winding and between each winding and the core 50. In addition, insulating tape 60, insulating tape 61 and other insulating tapes are, for example, combination tapes consisting of a base material made of polyester film bonded to polyester nonwoven fabric and an acrylic or silicone adhesive, or tapes with a base material made of polyester film, polyethylene terephthalate film, polyimide film, Nomex paper, mica, nonwoven fabric such as glass fiber, or polyphenylene sulfide film.

[0014] The first winding 20 is wound around the bobbin 10. More specifically, the first winding 20 is wound around the portion of the outer circumferential surface 11a between the insulating tapes 60. The first winding 20 is the primary winding of the transformer 100. The first winding 20 is a round wire made of, for example, copper, a copper alloy, aluminum, or an aluminum alloy. Although not shown, the leading end of the first winding 20 is wound around a pin of the bobbin 10. Although not shown, the leading and leading ends of the first winding 20 are insulated by insulating tape.

[0015] The first insulating layer 30 is disposed so as to cover the first winding 20 and the insulating tape 60. The first insulating layer 30 is formed by winding insulating tape around the first winding 20 and the insulating tape 60. The insulating tape is, for example, polyester tape. The first insulating layer 30 has an outer peripheral surface 30a. Insulating tape 61 is wound around the outer peripheral surface 30a in positions adjacent to the flanges 12 and 13. The insulating tape 61 is wound to ensure an insulating distance between each winding and between each winding and the core 50.

[0016] The second winding 21 is wound around the bobbin 10 (tubular portion 11) with the first winding 20 and the first insulating layer 30 interposed therebetween. That is, the first insulating layer 30 is interposed between two adjacent windings. More specifically, the second winding 21 is wound around the portion of the outer circumferential surface 30a between the insulating tapes 61. The second winding 21 is a secondary winding of the transformer 100. The second winding 21 is a round wire made of, for example, copper, a copper alloy, aluminum, or an aluminum alloy. Although not shown, the leading end of the second winding 21 is wound around a pin of the bobbin 10. Although not shown, the leading and leading ends of the second winding 21 are insulated by insulating tape. The winding width of the second winding 21 in the axial direction is, for example, smaller than the winding width of the first winding 20 in the axial direction.

[0017] The first insulating layer 30 has a first layer 31, a second layer 32, and a first intermediate conductor 33. The first layer 31 and the second layer 32 are located on the first winding 20 side and the second winding 21 side, respectively. The thickness of the first layer 31 is preferably equal to the thickness of the second layer 32.

[0018] The first intermediate conductor 33 is disposed between the first layer 31 and the second layer 32. The first intermediate conductor 33 is not electrically connected to any other conductor of the transformer 100. That is, the first intermediate conductor 33 is at a floating potential. The first intermediate conductor 33 is, for example, a foil-shaped metal material. The first intermediate conductor 33 may be made of, for example, copper, aluminum, a copper-containing alloy, or an aluminum-containing alloy. The first intermediate conductor 33 may have a slit 33a (see FIG. 7 ). The slit 33a extends in the axial direction. The thickness of the first intermediate conductor 33 is not particularly limited. The first intermediate conductor 33 may, for example, completely cover the first layer 31. That is, both axial ends of the first intermediate conductor 33 extend to reach the flange 12 and the flange 13, respectively.

[0019] The second insulating layer 40 covers the second winding 21 and the insulating tape 61. That is, the second insulating layer 40 is interposed between the outermost winding and the core 50. The second insulating layer 40 is formed, for example, by winding insulating tape around the second winding 21 and the insulating tape 61. The core 50 is attached to the bobbin 10. The core 50 is made of, for example, a dust material (iron dust, sendust, permalloy), a ferrite material (nickel, manganese), a foil material (amorphous, finemet), etc.

[0020] <Modification> In the above example, the first winding 20 and the second winding 21 are made of round copper wire, but the shapes and materials of the first winding 20 and the second winding 21 are not limited to this. In the above example, the first intermediate conductor 33 is made of foil, but the shape of the first intermediate conductor 33 is not limited to this. The first intermediate conductor 33 may be, for example, mesh-shaped.

[0021] In the above example, the number of windings is two, but the number of windings may be three or more. When the number of windings is three or more, the number of first insulating layers 30 is also multiple, and a first insulating layer 30 is interposed between each pair of adjacent windings. When the number of windings is three or more, the multiple windings may include other windings in addition to the primary winding and secondary winding. The windings other than the primary winding and secondary winding included in the multiple windings may be, for example, auxiliary windings, bias windings, etc. In the above example, the innermost winding is the primary winding of the transformer 100, and the outermost winding is the secondary winding of the transformer, but the winding order and winding method may be different. The shapes of the bobbin 10 and the core 50 are not limited to those in the above example.

[0022] (Effect of Trans 100) The effects of the transformer 100 will be described below in comparison with a transformer according to a comparative example, which will be referred to as transformer 100A.

[0023] FIG. 3 is a cross-sectional view of the transformer 100A. As shown in FIG. 3, the configuration of the transformer 100A is the same as that of the transformer 100, except that the first insulating layer 30 does not have a first intermediate conductor 33. Because the first insulating layer 30 is formed by winding insulating tape, defects (e.g., voids 30b, see FIGS. 7 and 9) inevitably occur in the first insulating layer 30. This is also true when the first insulating layer 30 is formed from a resin mold. Under such circumstances, the electric field intensity increases in the voids 30b, which can cause localized partial discharges. Such partial discharges cause insulation degradation and ultimately lead to insulation breakdown.

[0024] FIG. 4 is a graph showing the relationship between the thickness of the first insulating layer 30 and the partial discharge inception voltage between the first winding 20 and the second winding 21. As shown in FIG. 4, the partial discharge inception voltage between the first winding 20 and the second winding 21 is proportional to the ½ power of the thickness of the first insulating layer 30. In other words, if the partial discharge inception voltage when the thickness of the first insulating layer 30 is T is V, then if the thickness of the first insulating layer 30 is ½×T, the partial discharge inception voltage becomes (1 / √2×V), and if the thickness of the first insulating layer 30 is 2×T, the partial discharge inception voltage becomes √2×V. Therefore, to make partial discharges less likely to occur in the transformer 100A (to increase the partial discharge inception voltage), it is necessary to increase the thickness of the first insulating layer 30. As a result, in order to make partial discharges less likely to occur in the transformer 100A, the transformer 100A must be increased in size.

[0025] FIG. 5 is a schematic diagram illustrating the effect of the transformer 100. As described above, in the transformer 100, the first insulating layer 30 includes a first layer 31 and a second layer 32, and the first intermediate conductor 33 is disposed between the first layer 31 and the second layer 32. The first intermediate conductor 33 is at a floating potential. Therefore, the potential of the first intermediate conductor 33 is determined by the potentials of the first winding 20 and the second winding 21. More specifically, as shown in FIG. 5, the first intermediate conductor 33, the first winding 20, and the first layer 31 form a capacitance C1, and the first intermediate conductor 33, the second winding 21, and the second layer 32 form a capacitance C2. Therefore, for example, if the capacitances C1 and C2 are equal to each other, the potential difference between the first intermediate conductor 33 and the first winding 20 and the potential difference between the first intermediate conductor 33 and the second winding 21 are half the potential difference between the first winding 20 and the second winding 21.

[0026] As a result, if the thickness of the first insulating layer 30 is T, the partial discharge inception voltage of the first layer 31 and the partial discharge inception voltage of the second layer 32 are both (1 / √2) × V, and partial discharge will not occur in the first insulating layer 30 until the potential difference between the first winding 20 and the second winding 21 reaches 2 × (1 / √2) × V = √2 × V. In this way, in the transformer 100, the potential difference between the first winding 20 and the second winding 21 is divided by the first intermediate conductor 33, thereby increasing the partial discharge inception voltage without increasing the thickness of the first insulating layer 30 and making it difficult for partial discharge to occur in the first insulating layer 30. From another perspective, the same partial discharge inception voltage can be maintained even if the thickness of the first insulating layer 30 is reduced. In the above example, even if the thickness of the first insulating layer 30 is 1 / 2 × T, the partial discharge inception voltage of the transformer 100 is the same as that of the transformer 100A when the thickness of the first insulating layer 30 is T.

[0027] A simulation was carried out to confirm the effect of arranging the first intermediate conductor 33. FIG. 6 is a perspective view showing a simulation model of the transformer 100. FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 6. As shown in FIGS. 6 and 7, in the simulation model of the transformer 100, voids 30b are arranged in the first layer 31. The shape of the voids 30b is spherical.

[0028] FIG. 8 is a perspective view showing a simulation model of the transformer 100A. FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. 8. As shown in FIGS. 8 and 9, the simulation model of the transformer 100A is identical to the simulation model of the transformer 100, except that the transformer 100A does not include the first intermediate conductor 33. According to the simulation results, the electric field strength in the void 30b of the transformer 100A ranged from 45.617 kV / m to 47.999 kV / m. On the other hand, the electric field strength in the void 30b of the transformer 100 ranged from 25.956 kV / m to 27.320 kV / m. From this comparison, it can be seen that disposing the first intermediate conductor 33 between the first layer 31 and the second layer 32 weakens the electric field strength in the void in the first insulating layer 30, making it less likely for partial discharge to occur.

[0029] In the transformer 100, the first intermediate conductor 33 not only makes it difficult for partial discharge to occur, but also reduces noise and improves heat dissipation. More specifically, switching noise from the primary side (first winding 20) is shielded by the first intermediate conductor 33, making it difficult for it to propagate to the secondary side (second winding 21). In addition, the first intermediate conductor 33 has a higher thermal conductivity than the first insulating layer 30, which allows heat inside the bobbin 10 to easily escape to the outside, thereby lowering the core temperature of the transformer 100. In the transformer 100, the first intermediate conductor 33 has slits 33a formed therein, which makes it possible to suppress short circuits (short turns) between windings that can cause heat generation and noise.

[0030] Embodiment 2 A transformer according to embodiment 2 will be described. The transformer according to embodiment 1 is referred to as transformer 200. Here, differences from transformer 100 will be mainly described, and overlapping descriptions will not be repeated.

[0031] (Transformer 200 configuration) The configuration of the transformer 200 will be described below.

[0032] 10 is a cross-sectional view of the transformer 200. FIG. 10 shows a cross section of the transformer 200 taken along the line II-II in FIG. 1. As shown in FIG. 10, the transformer 200 includes a bobbin 10, a first winding 20, a second winding 21, a first insulating layer 30, a first intermediate conductor 33, a second insulating layer 40, a core 50, an insulating tape 60, and an insulating tape 61. In this respect, the configuration of the transformer 200 is the same as that of the transformer 100.

[0033] In the transformer 200, the first layer 31 is not completely covered by the first intermediate conductor 33. That is, in the transformer 200, both axial ends of the first intermediate conductor 33 do not extend to reach the flange 12 and the flange 13, respectively. More specifically, the axial width of the first intermediate conductor 33 matches the axial winding width of the first winding 20. In this respect, the configuration of the transformer 200 differs from the configuration of the transformer 100.

[0034] <Modification> In the above, an example has been described in which the winding width in the axial direction of the first winding 20 is larger than the winding width in the axial direction of the second winding 21, and the width in the axial direction of the first intermediate conductor 33 matches the winding width in the axial direction of the second winding 21. However, if the winding width in the axial direction of the first winding 20 is smaller than the winding width in the axial direction of the second winding 21, the width in the axial direction of the first intermediate conductor 33 may also match the winding width in the axial direction of the second winding 21.

[0035] (Trans 200 effect) The effects of the transformer 200 will be explained below.

[0036] 11 is a schematic diagram illustrating the effect of the transformer 200. As shown in Fig. 11, in the transformer 200 as well, the first intermediate conductor 33, the first winding 20, and the first layer 31 form a capacitance C1, and the first intermediate conductor 33, the second winding 21, and the second layer 32 form a capacitance C2. Therefore, in the transformer 200, as in the transformer 100, the potential difference between the first winding 20 and the second winding 21 is divided by the first intermediate conductor 33, making it possible to suppress the onset of partial discharge without reducing or changing the thickness of the first insulating layer 30.

[0037] Furthermore, in the transformer 200, the first intermediate conductor 33 does not extend to reach the flange portions 12 and 13, so it is possible to have a large dimensional tolerance for the first intermediate conductor 33 relative to the dimensions of the bobbin 10, thereby improving workability.

[0038] Embodiment 3 A transformer according to embodiment 3 will be described. The transformer according to embodiment 1 is referred to as transformer 300. Here, differences from transformer 100 will be mainly described, and overlapping descriptions will not be repeated.

[0039] (Transformer 300 configuration) The configuration of the transformer 300 will be described below.

[0040] 12 is a cross-sectional view of transformer 300. FIG. 12 shows a cross section of transformer 300 taken along the line II-II in FIG. 1. As shown in FIG. 12, transformer 300 includes bobbin 10, first winding 20, second winding 21, first insulating layer 30, first intermediate conductor 33, second insulating layer 40, core 50, insulating tape 60, and insulating tape 61. In this respect, the configuration of transformer 300 is the same as that of transformer 100.

[0041] In the transformer 300, the second insulating layer 40 has a third layer 41, a fourth layer 42, and a second intermediate conductor 43. The thickness of the third layer 41 is preferably equal to the thickness of the fourth layer 42. The third layer 41 and the fourth layer 42 are located on the second winding 21 side and the core 50 side, respectively. The third layer 41 and the fourth layer 42 are formed, for example, by winding insulating tape.

[0042] The second intermediate conductor 43 is disposed between the third layer 41 and the fourth layer 42 and is at a floating potential. The second intermediate conductor 43 is a foil-shaped metal material, and is made of copper, a copper-containing alloy, aluminum, an aluminum-containing alloy, or the like. Although not shown, the second intermediate conductor 43 has a slit formed therein that extends along the axial direction.

[0043] The transformer 300 further includes a third insulating layer 70. The third insulating layer 70 is disposed on the outer peripheral surface 11a, and the first winding 20 is wound around the third insulating layer 70. From another perspective, the third insulating layer 70 is interposed between the innermost winding and the bobbin 10. The third insulating layer 70 includes a fifth layer 71, a sixth layer 72, and a third intermediate conductor 73. The fifth layer 71 and the sixth layer 72 are located on the bobbin 10 (tubular portion 11) side and the first winding 20 side, respectively. The fifth layer 71 and the sixth layer 72 are formed by winding insulating tape, for example.

[0044] The third intermediate conductor 73 is disposed between the fifth layer 71 and the sixth layer 72 and is at a floating potential. The third intermediate conductor 73 is a foil-shaped metal material, and is made of aluminum, copper, or the like. Although not shown, the third intermediate conductor 73 has a slit extending along the axial direction.

[0045] (Effect of Trans 300) The effects of the transformer 300 will be explained below.

[0046] 13 is a first schematic diagram illustrating the effect of the transformer 300. As shown in Fig. 13, in the transformer 300, the second intermediate conductor 43, the second winding 21, and the third layer 41 form a capacitance C3, and the second intermediate conductor 43, the core 50, and the fourth layer 42 form a capacitance C4. Therefore, in the transformer 300, the potential difference between the second winding 21 and the core 50 is divided by the second intermediate conductor 43, making it possible to suppress the onset of partial discharge without reducing or changing the thickness of the second insulating layer 40.

[0047] Fig. 14 is a second schematic diagram illustrating the effect of the transformer 300. As shown in Fig. 14, in the transformer 300, the third intermediate conductor 73, the core 50, the bobbin 10 (the cylindrical portion 11), and the fifth layer 71 form a capacitance C5, and the second intermediate conductor 43, the first winding 20, and the sixth layer 72 form a capacitance C6. Therefore, in the transformer 300, the potential difference between the first winding 20 and the core 50 is divided by the third intermediate conductor 73, making it possible to suppress the onset of partial discharge without reducing or changing the thickness of the third insulating layer 70.

[0048] (Addendum) Aspects of the present disclosure are summarized in the appendix.

[0049] <Appendix 1> Bobbin and a plurality of windings; a plurality of insulating layers; the plurality of windings are wound around the bobbin; the plurality of insulating layers includes at least one first insulating layer interposed between two adjacent ones of the plurality of windings; A transformer, wherein each of the at least one first insulating layer has a first layer, a second layer, and a first intermediate conductor interposed between the first layer and the second layer and set to a floating potential.

[0050] <Appendix 2> It also has a core, the core is attached to the bobbin; the plurality of insulating layers includes a second insulating layer interposed between one of the plurality of windings at an outermost periphery and the core, 2. The transformer of claim 1, wherein the second insulating layer includes a third layer, a fourth layer, and a second intermediate conductor interposed between the third layer and the fourth layer and set to a floating potential.

[0051] <Appendix 3> the plurality of insulating layers includes a third insulating layer interposed between an innermost one of the plurality of windings and the bobbin; 3. The transformer of claim 1, wherein the third insulating layer includes a fifth layer, a sixth layer, and a third intermediate conductor interposed between the fifth layer and the sixth layer and set to a floating potential.

[0052] <Appendix 4> the number of the plurality of windings is three or more; 4. The transformer according to claim 1, wherein the at least one first insulating layer is a plurality of first insulating layers.

[0053] <Appendix 5> A power converter comprising the transformer according to any one of Supplementary Note 1 to Supplementary Note 4.

[0054] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of this application is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0055] 10 bobbin, 11 cylindrical portion, 11a outer circumferential surface, 12 flange portion, 13 flange portion, 20 first winding, 21 second winding, 30 first insulating layer, 30a outer circumferential surface, 30b void, 31 first layer, 32 second layer, 33 first intermediate conductor, 33a slit, 40 second insulating layer, 41 third layer, 42 fourth layer, 43 second intermediate conductor, 50 core, 60 insulating tape, 61 insulating tape, 70 third insulating layer, 71 fifth layer, 72 sixth layer, 73 third intermediate conductor, 100, 100A transformer, 200 transformer, 300 transformer, C1, C2, C3, C4, C5, C6 capacitance.

Claims

1. Bobbin and A plurality of windings; A plurality of insulating layers; The plurality of windings are wound around the bobbin, the plurality of insulating layers includes at least one first insulating layer interposed between two adjacent ones of the plurality of windings; each of the at least one first insulating layer has a first layer, a second layer, and a first intermediate conductor interposed between the first layer and the second layer and at a floating potential.

2. Further equipped with a core, The core is attached to the bobbin, the plurality of insulating layers includes a second insulating layer interposed between one of the plurality of windings at an outermost periphery and the core, 2. The transformer of claim 1, wherein the second insulating layer includes a third layer, a fourth layer, and a second intermediate conductor interposed between the third layer and the fourth layer and set to a floating potential.

3. the plurality of insulating layers includes a third insulating layer interposed between an innermost one of the plurality of windings and the bobbin; 2. The transformer of claim 1, wherein the third insulating layer includes a fifth layer, a sixth layer, and a third intermediate conductor interposed between the fifth layer and the sixth layer and set to a floating potential.

4. The number of the plurality of windings is three or more, The transformer of claim 1 , wherein the at least one first insulating layer is a plurality of first insulating layers.

5. A power converter comprising the transformer according to any one of claims 1 to 4.

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