JP2013021307A - High frequency transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency transformer including a new winding structure corresponding to a frequency increase and a capacity increase.SOLUTION: The high frequency transformer includes an iron core 1 acting as a main magnetic flux path with an iron core center leg 1a provided in the center portion thereof, and coils 4, 3 and 5 having cylindrical longitudinally-wound structures spirally wound with the iron core center leg 1a as a center. The coils 4, 3 and 5 form a primary side coil 3 and secondary side coils 4 and 5 which are electromagnetically coupled, the primary side coil 3 and the secondary side coils 4 and 5 are each formed by a continuous belt-like conductor plate 14 having an almost rectangular cross section, the belt-like conductor plate 14 is bent toward the reverse side or the front side two or more times on a crease 16 at an angle other than parallel with a current passing direction and the vertical, and as to bending of the belt-like conductor plate 14 toward the front side or the reverse side with respect to the current passing direction, it is bent continuously toward the same sides at least once, either toward the front side or toward the reverse side, in one turn of the coils 3-5. Thus, the belt-like conductor plate 14 has a spiral and cylindrical longitudinally-wound coil structure.

Description

  The present invention relates to a high frequency transformer, and more particularly to a high frequency transformer for a switching power supply.

  In a switching power supply (hereinafter simply referred to as a power supply) configured to electrically insulate the primary side and the secondary side, a conversion transformer (hereinafter simply referred to as a transformer) is used for the insulation. Conventionally, as the conversion transformer, a winding transformer in which a copper wire is wound around an iron core serving as a main magnetic flux path or a sheet transformer in which a foil copper plate is wound has been used. Recently, a so-called rectangular wire (or ribbon copper wire) whose conductor cross section is not circular has been used, and a coil obtained by processing a conductor having a rectangular cross section has been used.

  In recent years, in addition to further miniaturization and higher efficiency of the power supply, it is required to handle a large capacity of about several kW, and the high-frequency response of power supply semiconductor components is being promoted. On the other hand, the transformer can be miniaturized by increasing the frequency, but it is essential to reduce the loss related to the efficiency. To that end, in addition to adopting a low-loss core material, reduce the DC resistance and AC resistance of the coil that leads to copper loss (skin effect in conductor, proximity effect between conductors, eddy current loss due to leakage flux from iron core) It is necessary. In reducing copper loss, conventional winding transformers have problems of skin effect and proximity effect. For this reason, a wire rod called a litz wire, which is formed by bundling thin conductor wires, is used, but this is expensive, and it is not easy to remove the insulating film of the wire in the terminal connection process, so workability is improved. I have the problem of being bad. The problem of proximity effect remains in the sheet transformer system. In view of these problems, various techniques for a high-frequency transformer using a rectangular wire are disclosed. For example, Patent Document 1 describes one of the techniques.

  In Patent Document 1, a structure (edgewise structure) in which a rectangular conductive wire is vertically wound in the width direction of the conductor cross section is taken. In order to cope with higher frequencies and to pass a large current, it is necessary to reduce the thickness of the rectangular wire and increase the width. In Patent Document 1, a flat wire is divided into two in the width direction, and the conductor cross-sectional area is equalized between the inner and outer coils after machining deformation, and a large current is obtained by connecting them in parallel. It corresponds to the conversion.

  In Patent Document 2, when a flat wire having a winding start end and a winding end is sequentially wound from the winding start end to the winding end, the plane side of the flat wire is sequentially set at an arbitrary angle. The laminated winding is characterized in that it is provided with a plurality of bent portions and is pressed so that the bent portions are in close contact with each other and rolled so that each bent portion approaches the thickness of the rectangular wire. Yes. In the winding coil having this configuration, the degree of adhesion between the wires is increased, and the conductor space factor can be further increased.

JP-A-9-7854 (page 4, FIG. 1) Japanese Patent No. 4573323 (page 5, FIG. 1)

However, in the recent increase in driving frequency, for example, assuming that the frequency is 100 kHz and the current 10A flows through the coil, the thickness of the flat wire is at least the skin thickness d defined by the following formula (1) (copper wire) 0.2 mm). Moreover, if the current density of the conducting wire is 5 to 6 A / mm ² , the width of the flat wire needs to be at least 9 mm. As a result, the width / thickness ratio (hereinafter referred to as flatness) is preferably 30. Will be exceeded.

  Here, ρ is electric resistance, f is frequency, and μ is magnetic permeability.

  The flatness that can be finished into a flat wire is about 30 at the maximum although it depends on the plate thickness. In the case of a rectangular wire having a thickness of 0.2 mm, the flatness that can be produced is at most about 5. To obtain a width of 9 mm, nine rectangular wires are connected in parallel. However, it is very difficult to make a plurality of lines into a vertical winding similar to a single rectangular line. Further, in order to wind a rectangular wire vertically, a special winding machine with plastic working using a mold is required, and there is a problem that the production cost is higher than that of winding a round wire.

  In Patent Document 2, in order to solve this problem, a plurality of bent portions are sequentially bent at an arbitrary angle on the flat side of the flat wire, and the bent portions are pressed so as to be in close contact with each other. The coil can be wound vertically by rolling to approach the thickness. However, a rolling mill for pressing and rolling the bent portion to be plastically deformed is necessary, and there is a problem that the manufacturing process is complicated and the cost is increased. In addition, it is necessary to control the interval between the turns of the coil by the pressure contact ratio at each bent portion, and there is a problem that it is not easy to ensure the uniformity of the coil stacking interval.

  As described above, it is difficult to further increase the frequency and increase the capacity of the transformer in the vertical winding method in which the conventional rectangular conducting wire is plastically deformed.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a high-frequency transformer having a new winding structure corresponding to high frequency and large capacity.

  The present invention provides a high-frequency circuit including an iron core central leg provided at a central portion, a core serving as a main magnetic flux path, and a coil having a cylindrical vertical winding structure spirally wound around the iron core central leg. The transformer includes a primary side coil and a secondary side coil that are electromagnetically coupled, and the primary side coil and the secondary side coil are continuous strip-shaped conductors each having a substantially rectangular cross section. The strip-shaped conductor plate is formed from a plate, and has a spiral cylindrical longitudinally wound coil structure that is bent a plurality of times on the back side or the front side at an angle other than parallel and perpendicular to the current-carrying direction. In one turn of the coil, the band-like conductor plate is bent at the front side or the back side with respect to the direction of current application at least once and continuously bent to the same side of the front side or the back side. G Is Nsu.

  The present invention provides a high-frequency circuit including an iron core central leg provided at a central portion, a core serving as a main magnetic flux path, and a coil having a cylindrical vertical winding structure spirally wound around the iron core central leg. The transformer includes a primary side coil and a secondary side coil that are electromagnetically coupled, and the primary side coil and the secondary side coil are continuous strip-shaped conductors each having a substantially rectangular cross section. The strip-shaped conductor plate is formed from a plate, and has a spiral cylindrical longitudinally wound coil structure that is bent a plurality of times on the back side or the front side at an angle other than parallel and perpendicular to the current-carrying direction. In one turn of the coil, the band-like conductor plate is bent at the front side or the back side with respect to the direction of current application at least once and continuously bent to the same side of the front side or the back side. G Since in Nsu, it is possible to realize a high-frequency transformer with a new winding structure corresponding to high frequency and large capacity.

It is sectional drawing which shows the high frequency transformer and winding structure by Embodiment 1 of this invention. It is a figure which shows the winding preparation procedure of the high frequency transformer by Embodiment 1 of this invention. It is sectional drawing which shows the winding structure of the high frequency transformer by Embodiment 2 of this invention. It is sectional drawing which shows the winding structure of the high frequency transformer by Embodiment 2 of this invention, and the figure which compared the influence on the primary side leakage inductance. It is the figure which compared the influence on the copper loss of the secondary coil conductor thickness by Embodiment 2 of this invention. It is sectional drawing which shows the winding structure of the high frequency transformer by Embodiment 3 of this invention. It is the figure which compared the influence on the primary side leakage inductance of the high frequency transformer by Embodiment 3 of this invention. It is the perspective view which showed the structure of the E-type core and coil bobbin of the high frequency transformer by Embodiment 1 of this invention.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a high-frequency transformer and winding configuration according to Embodiment 1 of the present invention. 1A is a side sectional view of the high-frequency transformer according to the first embodiment, FIG. 1B is a top view of the strip-shaped conductor plate 14 constituting the coil of the high-frequency transformer according to the first embodiment, and FIG. (C) is a side view of the strip-shaped conductor plate 14 of FIG.1 (b).

  As shown in FIG. 1, the high-frequency transformer according to the first embodiment includes an iron core 1 having an iron core central leg 1a at the center, a coil bobbin 2 provided for the iron core central leg 1a, and a coil bobbin 2. The plurality of coils 3, 4 and 5 are wound around the iron core central leg 1a. The plurality of coils 3, 4, 5 constitute an electromagnetically coupled primary side coil 3 and secondary side coils 4, 5. The iron core 1 is configured by combining a plurality of E-type or EI-shaped E-type cores 1b as shown in FIG. 7A, for example. The shape of the side surface of the E-type core 1b is substantially E-shaped, and is substantially U-shaped except for the portion that becomes the central iron core central leg 1a. After the combination of the two E-shaped cores 1b, the portion 1c extending in the vertical direction at both ends of the U-shaped portion becomes the side wall portion of the high-frequency transformer, while the portion 1d sandwiched between the portions 1c is It becomes the upper plate portion or the lower plate portion of the high-frequency transformer. In addition, a quadrangular prism-shaped member having a substantially square cross section is provided at the central portion of the portion 1d of each E-type core 1b. Become. Further, for example, a coil bobbin 2 as shown in FIG. 7B is fitted to the iron core central leg 1a. In the coil bobbin 2, as shown in FIG. 7B, the upper plate and the lower plate are each a substantially donut shape of the same shape, the central portion is hollow inside, and the outer shape is substantially square. It is a square tube. As an assembling process, before the two E-type cores 1b are vertically connected and fixed, the coil bobbin 2 and the coil 5, coil 3, and coil 4 wound up spirally are attached to one E-type core 1b. Then, the other E-type core 1b is formed together. The iron core 1, the coil bobbin 2, and the coils 3 to 5 are configured as described above, and the coil 5, the coil 3, and the coil 4 are sequentially wound around the iron core central leg 1a via the coil bobbin 2 in a spiral manner. .

  The coil 3 is a primary-side vertical coil (hereinafter referred to as primary-side vertical coil 3), and the coils 4 and 5 are secondary-side vertical coils (hereinafter referred to as secondary-side vertical winding No. 1 coil 4 and Secondary side vertical winding No. 2 coil 5). Primary side vertical winding coil 3, secondary side vertical winding No. 1 coil 4 and secondary side vertical winding No. The two coil 5 is a secondary side vertical winding No. No. 1 coil 4, primary side vertical winding coil 3, secondary side vertical winding No. 2 coils 5 are arranged in series in the order of the secondary side vertical winding No. 1 coil 4 and secondary side vertical winding No. The two coils 5 are connected in series. In the first embodiment, these coils 3 to 5 are formed by alternately bending a straight strip-shaped conductor plate 14 a plurality of times on the front side and the back side. The band-shaped conductor plate 14 after being bent is a coil having a cylindrical vertical winding structure wound spirally. In the first embodiment, the primary-side vertical winding coil 3 is connected to the secondary-side vertical winding No. 1 coil 4 and secondary side vertical winding No. Although the configuration in which the two coils 5 are sandwiched is adopted, the configuration is not limited to this, and conversely, the configuration in which the primary side longitudinally wound coil 3 is divided and the secondary side longitudinally wound coil is sandwiched at the center, or each coil. Can be arbitrarily selected in accordance with the coupling performance required for the transformer, such as a configuration in which the coils are arranged in series without being divided. Moreover, although this Embodiment demonstrates the example which comprises the coils 3-5 from the one continuous strip | belt-shaped conductor board 14, it does not restrict to that case but each strip | belt 3-5 is each one strip | belt-shaped conductor board. 14 may be formed separately from each other, the three spirally wound coils may be arranged in series, and the two secondary coils may be connected in series. Thus, each coil 3-5 should just be what the primary side coil and the secondary side coil electromagnetically coupled, and the arrangement | sequence order and number of each coil 3-5 can be changed suitably.

  Hereinafter, the configuration of the high-frequency transformer according to the first embodiment will be described in more detail. As described above, the high-frequency transformer according to the first embodiment has one core center leg 1a of the iron core 1 that forms a closed magnetic circuit (main magnetic flux path) by combining the E-type or EI-shaped E-type core 1b. The primary-side vertical winding coil 3 and two secondary-side vertical winding Nos. 1 coil 4 and secondary side vertical winding No. The two coils 5 are wound in a tandem arrangement in the direction of the axis of symmetry 6 of the iron core, and all of the coils 4, 3, 5 wound vertically around the iron core central leg 1a are substantially rectangular ( (Rectangular) cross section, which is composed of a single straight strip-shaped conductor plate 14. As shown in FIG. 1B, the strip-shaped conductor plate 14 is folded back and forth alternately on the back side and the front side of the strip-shaped conductor plate 14 at folds 16 at angles other than parallel and perpendicular to the current-carrying direction 8. As a whole, it is wound up spirally so as to surround the iron core central leg 1a. As a result, for example, in FIG. 1B, the surface of the conductor faces upward in the portion 17a of the strip-shaped conductor plate 14, the back surface of the conductor faces upward in the portion 17b, and the surface of the conductor again in the portion 17c. Facing upward, and the back surface of the conductor again faces upward in the 17d portion. In this way, the strip-shaped conductor plate 14 is alternately folded back on the front side of the conductor and then on the back side.

  What is necessary is just to adjust suitably the space | interval of the crease | fold 16 and the bending angle of the strip | belt-shaped conductor board 14 according to the shape of the iron core center leg 1a which penetrates the coils 3-5. In the first embodiment, as shown in FIG. 1 (b), since the iron core central leg 1a has a substantially square cross section, the strip-shaped conductor plate 14 has an angle of ± 45 degrees with respect to the direction of current flow. On the front side or the back side of the conductor, a quadrilateral coil is formed that is alternately folded and is in contact with the iron core central leg 1a having a square cross section as a whole. In the first embodiment, an example in which the iron core central leg 1a has a square cross section has been described. However, the present invention is not limited to a square, and other rectangles such as rectangles, polygons, etc. Good. In addition, an angle of ± 45 degrees with respect to the direction of current flow is given as an example, but this is a case where the shape of the iron core central leg 1a is rectangular, and in the case of other shapes, the angle is appropriately set accordingly. decide. The angle may be an arbitrary angle as long as it is an angle other than parallel and vertical, and therefore, the smaller one of the angles with respect to the direction of current application may be an angle larger than 0 degree and smaller than ± 90 degrees.

  In addition, although consistency between FIG. 1C and FIG. 1B is not taken, this is for simplifying the drawing, and although FIG. 1C shows two turns of the coil. In FIG. 1 (b), only one turn of the coil is shown, and the results are not consistent in these drawings. In these drawings, for simplification of the drawing, only one turn of the coil or two turns of the coil are shown, but actually, it is necessary to configure the coils 4, 3, and 5. It goes without saying that minutes of turns (many turns) are stacked.

  FIG. 2 is a diagram showing a folded coil manufacturing process using the strip-shaped conductor plate 14 shown in FIG. In FIG. 2, 12 is a strip conductor constituting the strip conductor plate 14, 12a to 12h are portions of the strip conductor 12 (corresponding to 17 in FIG. 1), and 13a to 13g are folds (corresponding to 16 in FIG. 1). It is.

  The strip-shaped conductor 12 is formed by cutting a wide plate-shaped conductor into a predetermined width by a slitter (not shown) and then forming an strip with an insulating film. The insulating film is applied not only to the front and back surfaces of the conductor, but also to the side surfaces that are cut surfaces. This state is shown in FIG. Next, in order to bend the strip-shaped conductor 12, the strip conductor 12 is fed along the winding forming jig 10 in the feeding direction 11, and as shown in FIG. At 13b, it is once bent to the left (valley fold as viewed from the front surface of the belt-like conductor). Next, as shown in FIGS. 2 (c) to 2 (d), it is bent to the right (folded as viewed from the surface of the belt-like conductor) at a fold 13a that forms an angle of -45 degrees with respect to the direction of current flow, and further to the direction of current flow. Bending in the right hand at the crease 13c forming an angle of −45 degrees (valley fold as viewed from the side surface of the belt-like conductor), and finally bending to the right hand in the crease 13d forming an angle of −45 degrees with respect to the direction of current application ( When viewed from the front side of the strip conductor, the coil is formed for one turn. As described above, by folding the portion 12c at the fold line 13b before the portion 12b, the folding direction of the strip-shaped conductor can be aligned (in this embodiment, from the bottom normal direction to the top). The workability at the time of bending the coil can be improved.

  What should be noted as a way of folding at this time is that the strip-shaped conductor plate 14 needs to be folded spirally so as to surround the winding forming jig 10, so when folding the strip-shaped conductor plate 14, After each side portion of the strip-shaped conductor plate 14 is bent, a side corresponding to the outer side (side opposite to the side on the winding forming jig 10 side) is bent by one turn of the coil, and then the winding forming jig 10 is turned. Fold it to the side. By repeating this, the strip-shaped conductor plate 14 is spirally wound in the clockwise or counterclockwise direction. Specifically, when the portion 12b of FIG. 2A is folded at the fold line 13a, the longest side of the substantially trapezoidal 12b portion is outside in the state of FIG. 2A before folding. However, after bending, the longest side on the outer side comes to the winding forming jig 10 side as shown in FIG. Further, the portion 12c is also bent before the portion 12b. After the portion 12b is bent, the longest side that is on the outer side is the winding forming jig 10 side as shown in FIG. 2 (c). Have come to. This is the same when folding to the front side (valley fold) and folding to the back side (mountain fold). In this way, the belt-like conductor plate 14 is formed along the outer periphery of the winding forming jig 10 by folding the side that was on the outside before the bending so that the side is on the winding forming jig 10 side after the bending. It is rolled up in a spiral form.

  The strip-shaped conductor plate 14 according to the first embodiment is not completely alternating between the valley fold and the mountain fold, such as “valley, valley, valley, mountain, valley, valley, valley, mountain,... The point is that the valley folds are folded back at least once. In the first embodiment, since “valley, valley, valley, mountain, valley, valley, valley, mountain,...”, The valley fold in the same direction is continued twice after the valley fold. However, the present invention is not limited to this, and mountain folds may be repeated twice, such as “valley, mountain, mountain, mountain, valley, mountain, mountain, mountain,... The number of turns may be any number, but preferably the number of turns is an even number of 4 or more and the number of turns in a different direction is one. However, when the winding forming jig 10 has a square cross section, it is desirable that the winding is continuous twice.

  Thus, in the process of forming the coil 1 turn, the band-shaped conductor plate 14 according to the first embodiment is not completely alternate between the front and back sides of the band-shaped conductor plate 14 when the band-shaped conductor plate 14 is bent to the front and back in the current conduction direction. This is a type of partial alternating folding that is continuously on the same side at least once.

  In the present embodiment, as shown in FIG. 1 (b), the strip-shaped conductor plate 14 is valley-folded at the fold 16a, valley-folded at the fold 16b, valley-folded at the fold 16c, and finally mountain-folded. The coil side surface state of (c) is formed. For this reason, when considering the thickness of the sheet piled up each time the strip-shaped conductor plate 14 is folded back, as shown in FIG. 1C, in this embodiment, the coil 1 is folded three times in the same direction. Two turns are canceled for each turn, and the coil interval is “plate thickness × (bending number−non-alternating folding number × 2)”. Accordingly, in the case of a four-sided coil, the coil interval is “plate thickness × 2”.

  According to this configuration, it is possible to perform vertical winding at a narrow coil interval without pressing and rolling the folded portion as in Patent Document 2, and the iron core size in the coil winding direction can be made compact. In FIG. 1 (c), the stack size is two turns of the coil and the plate thickness is four sheets, and the front and back sides of the strip conductor are completely halved compared to the alternate folding. Accordingly, the size of the iron core can also be greatly reduced because the length of the iron core central leg 1a can be halved.

  On the other hand, when the iron core size is not changed, as shown in FIG. 3A (a), the turn-up curvature is changed by the curvature adjusting jig 31 in the turn-up after one turn is formed, and the coil is placed between the layers at the position of the coil bend. The coil interval can be adjusted to be constant by inserting and holding the interval adjusting insulator 32. Thereby, the leakage inductor of a primary side coil can be adjusted suitably. In a conventional power supply circuit, a resonance inductor is separately installed on the primary side of the transformer. If this is replaced with a leakage inductor of the transformer, the power supply device can be downsized and the cost can be reduced by reducing the number of components. 3B (b) to 3 (d) show the results of evaluating the change in the leakage inductor when the coil interval is changed by magnetic field analysis (using ferrite for the iron core). FIG. 3B (c) shows a case where the coil interval is normally bent, and FIG. 3B (d) shows a case where the coil interval is widened. In FIG. 3B (d) in which the coil interval is widened, the primary side leakage inductance can be reduced by 37% compared to FIG. 3B (c). In FIGS. 3A and 3B, the primary side longitudinally wound coil or the secondary side longitudinally wound coil is partially alternately folded, and the coil spacing is evenly given by setting the curvature to the same value by folding after forming one turn. Showed the case. Furthermore, if the turn-up curvature after the formation of one turn is appropriately changed, an uneven coil interval can be set, and thus the leakage inductor can be adjusted. Although it is possible to adjust the coil interval even with the longitudinal winding coil and the bending pressure welding coil that do not depend on the conventional bending, it is difficult to adjust the coil interval unevenly, and according to this embodiment, finer adjustment is possible. It becomes possible.

  As described above, in the first embodiment, in one turn of the coils 3 to 5, the folding of the strip-shaped conductor plate 14 to the front and back with respect to the current conduction direction is the same direction continuously at least once. As described above, as described above, the stack size of the coils 3 to 5 wound up spirally can be reduced as described above, so that the coils 3 to 5 are made compact, thereby significantly reducing the core size. The overall size of the high-frequency transformer can be reduced. Alternatively, when the iron core size is left as it is, the coil interval of the coils 3 to 5 can be appropriately changed with respect to the coil winding direction, so that not only the coils 3 to 5 are made compact, but also the primary side longitudinally wound coil. The primary side leakage inductor value can be adjusted by changing the coupling coefficient between 3 and the secondary side longitudinally wound coils 4 and 5.

Embodiment 2. FIG.
The ratio of the primary current flowing in the primary side longitudinal winding coil 3 of the high frequency transformer and the secondary current flowing in the secondary side longitudinal winding coils 4 and 5 depends on the number of windings of each of those coils, and the equation (2) It becomes a relationship.

_{A 1 / A 2 = N 2} / N 1 = 1 / a ··· (2)

Here, A ₁ is the primary current, A ₂ is the secondary current, N ₁ is the number of windings of the primary-side vertical winding coil 3, and N ₂ is the number of windings of the secondary-side vertical winding coils 4, 5. Moreover, a represents a winding number ratio.

For _example, N 2 _{/ N} 1 = if 2, from equation _{(2), A 2 = A} 1 /2,a=0.5 next, primary Tatemaki coil 3 and the secondary side Tatemaki coils 4 and 5 If the current density is designed to be equal, the cross-sectional area of the conductors of the secondary-side vertical coils 4 and 5 can be halved compared to the primary-side vertical coil 3. In the second embodiment, the winding ratio between the primary coil 3 and the secondary coils 4 and 5 has a relationship of 1: n (n is a real number of 1 or more), and the current density in the secondary coil is wound. In accordance with the number ratio, at least one of the coil width or the coil thickness is configured so that the primary coil is equal to the secondary coil until the current density of the primary coil is the same as the maximum primary coil. That is, the coil width (or coil thickness) value of the primary coil is configured to be equal to or greater than the coil width (or coil thickness) value of the secondary coil.

  FIG. 4 shows the case where the thickness of the strip-shaped conductor (conductor width 9 mm) of the secondary coil is 0.25 mm, which is the same as that of the primary coil, and the winding ratio is 0.15 mm in the configuration of FIG. 3B (d). Is a comparison of copper loss obtained by magnetic field analysis. In the analysis, a sine wave current (f = 10 kHz to 150 kHz) having an amplitude of 15 A is applied to the primary coil in the secondary side short-circuit state. The copper loss on the vertical axis is standardized based on the copper loss at a strip-shaped conductor t0.25 × 9 mm and 100 kHz. Copper loss at 100 kHz is reduced by 40% by making the conductor thickness of the secondary coil 0.1 mm thinner than the primary side. In the second embodiment, the winding ratio between the vertically wound primary side coil 3 and secondary side coils 4 and 5 has a relationship of 1: n (n is a real number of 1 or more), and the current in the secondary coil The coil thickness is configured so that the primary coil> = secondary coil until the density is the same as the current density of the maximum primary coil in accordance with the turn ratio, but this makes it possible to produce a high-efficiency high-frequency transformer. It becomes possible.

Embodiment 3 FIG.
FIG. 5 is a diagram showing the configuration of the high-frequency transformer according to the third embodiment of the present invention. FIG. 5A is a side sectional view of the high-frequency transformer according to the third embodiment, and FIG. 5B is a top view of the strip-shaped conductor plate according to the third embodiment. In FIG. 5, reference numeral 21 denotes a strip-shaped conductor plate corresponding to the strip-shaped conductor plate 14 of FIG. In FIG. 5, the configurations indicated by reference numerals 1 to 6 are the same as the configurations indicated by reference numerals 1 to 6 in FIG. 1. 25A and 25B are parts of the coils 3 to 5 (hereinafter simply referred to as “parts”), and 25B2, 25B3, 25B4, 25A1 and 25A2 are folding intervals (hereinafter simply referred to as “intervals”) of the strip-shaped conductor plate 21, respectively. 25A ′ and 25B ′ are inner diameters (opening openings) of the cross section of the internal space of the coil through which the iron core central leg 1a penetrates in the portions 25A and 25B of the cylindrical coils 3 to 5, respectively. This internal space of the coil is hereinafter referred to as a window.

  The third embodiment is a modification of the above-described second embodiment. A difference between the third embodiment and the second embodiment will be described. As shown in FIG. 1, the coil configuration of the second embodiment is different from that of the first embodiment except that the conductor thickness of the secondary coil is different from that of the first embodiment. (See also fold line 13 in FIG. 2). The length is always constant (since the crease 16 has a trapezoidal shape, it means that the lengths of the short sides and the long sides are the same). However, in the third embodiment, the length between adjacent creases 16 is variable. This can be seen from, for example, a comparison between FIGS. 1A and 1B showing the first embodiment and FIGS. 5A and 5B showing the third embodiment. In the third embodiment, the length between adjacent creases in one turn indicated by the solid line in FIG. 5B is equal to the adjacent crease in one turn indicated by the broken line in FIG. 5B. It is longer than the length between. Thus, in this Embodiment 3, the length between the bending of the strip | belt-shaped conductor board 21 is changed, and the window area (internal space of a cylindrical coil) which the iron core center leg 1a penetrates for every turn of a vertical polygon coil The cross-sectional area is appropriately changed in the coil winding direction. As a result, as shown in FIG. 5A, for example, the window area of the portion 25A of the coil 5 is large, and a gap (empty space) (strictly speaking, a coil bobbin between the iron core central leg 1a and the coil 5 is used. 2 and the coil 5, here referred to as a gap between the iron core central leg 1 a). On the other hand, the window area of the portion 25B of the coil 5 is the same as that of the coil 3 portion and is smaller than that of the portion 25A. Therefore, like the coil 3, there is no gap (empty space) between the iron core central leg 1 a and the coil 5. As a supplementary note, if the folding interval is increased with all the strip-like conductor plates having the same width, the coil collides with the portion 1c of the E-type core 1b. Therefore, it is desirable to use a thin strip-shaped conductor plate that can offset at least the increase in the folding interval at the portion where the folding interval is increased. In the example of FIG. 5, an example in which the core conductor plate having a narrower width than that of the coil 3 is used for the coils 4 and 5, and therefore, in the portion 25 </ b> B having the same window area as that of the coil 3, A gap (vacant space) is formed between the portion 1c and the coil 5. Further, in the portion 25A where the window area is larger than that of the coil 3, the coil 5 does not protrude from the portion 1c of the E-type core 1b, and is neatly accommodated to the extent that it is in contact with the portion 1c of the E-type core 1b.

  In the third embodiment, as shown in FIG. 5 (a), the length between the bending of the strip-shaped conductor plate 21 is variable because the secondary-side vertical winding No. 1 coil 4 and secondary side vertical winding No. There are two coils 5, and the primary side coil 3 is not variable.

  This is because the current density of the primary-side vertical winding coil 3 and the secondary-side vertical winding coils 4 and 5 is equalized from the relationship of the formula (2) and the winding ratio of 1: n (n is a real number of 1 or more). If the conductor cross-sectional area of the secondary-side vertical winding coils 4 and 5 is compared with the primary-side vertical winding coil 3, the conductor width can be reduced (if the conductor thickness is constant). If the conductor area of the secondary-side vertical winding coils 4 and 5 is reduced as compared with the primary-side vertical winding coil 3, the secondary-side vertical winding coils 4 and 5 have an empty space in the winding space in the iron core 1 as described above. . Using this empty space, for example, in the secondary side longitudinally wound coil 5, when winding from the portion 25B to the portion 25A, the folding interval of the belt-like conductor plate 21 is made variable, for example, as shown in FIG. When the bending intervals are, in order, the interval 25B2, the interval 25B3, the interval 25B4, the interval 25A1, the interval 25A2,... If it winds up, the width | variety (opening front opening) of the part 25B and 25A part of the secondary side vertical winding coil 5 in which the iron core center leg 1a penetrates will change from the opening front opening 25B 'to the larger opening front opening 25A'. Can be changed.

  On the other hand, when the folding interval is set to the interval 25B2, the interval 25B3, the interval 25B4, the interval 25A1, the interval 25A2,... If it winds up like this, the width of the window (opening front) of the part 25B, 25A part of the secondary side vertical winding coil 5 through which the iron core central leg 1a penetrates the opening front 25A 'rather than the front opening 25B' Can be reduced, and the opening opening 25B ′ can be changed to a smaller opening opening 25A ′.

  As a result, the primary side leakage inductor can be finely adjusted. FIG. 6 shows the result of analyzing the change in leakage inductance when the bending length of each side of the coil is changed and the window area of the secondary side vertical winding coils 4 and 5 through which the iron core central leg 1a passes is changed. Show. In the example of FIG. 6A, the window areas of the primary-side vertical winding coil 3 and the secondary-side vertical winding coils 4 and 5 are the same (all the coils 3 to 5 are in contact with the coil bobbin 2). Therefore, there is a gap (vacant space) between the secondary side longitudinally wound coils 4 and 5 and the portion 1c (not shown) of the E-type core 1b. On the other hand, in the example of FIG. 6B, the secondary-side vertical coils 4 and 5 are divided into secondary-side vertical coils 4A and 4B and secondary-side vertical coils 5A and 5B, respectively. The transition from the secondary-side vertical coil 4A to 4B (or vice versa) and the transition from the secondary-side vertical coil 5A to 5B (or vice versa) are performed by the method described with reference to FIG. Shall be changed. At this time, as shown in FIG. 6B, the folding interval of the strip-like conductor plates in the secondary side vertical winding coils 4B and 5B is the same as that of the primary side vertical winding coil 3, and therefore the primary side vertical winding coil 3 and The window areas of the secondary side longitudinally wound coils 4B and 5B are the same (both coils are in contact with the coil bobbin 2). However, since the width of the strip-shaped conductor plate constituting the secondary-side vertical coil 4B, 5B is narrower than the width of the strip-shaped conductor plate constituting the primary-side vertical coil 3, the secondary-side vertical coil 4B, 5B There is a gap (vacant space) between the portion 1c (not shown) of the E-type core 1b. On the other hand, since the folding interval of the secondary side vertical winding coils 4A and 5A is larger than that of the primary side vertical winding coil 3, the window area of the secondary side vertical winding coils 4A and 5A is larger than that of the primary side vertical winding coil 3. Therefore, there is a gap (vacant space) between the secondary side longitudinally wound coils 4A and 5A and the coil bobbin 2. In the example of FIG. 6C, the secondary-side vertical winding coils 4 and 5 are not divided into secondary-side vertical winding coils 4A and 4B and secondary-side vertical winding coils 5A and 5B, respectively. ) Secondary side vertical winding coils 4B and 5B are also secondary side vertical winding coils 4A and 5A. That is, the folding interval between the secondary side vertical winding coils 4A and 5A is larger than that of the primary side vertical winding coil 3, so that the window area of the secondary side vertical winding coils 4A and 5A is larger than that of the primary side vertical winding coil 3. Thus, there is a gap (vacant space) between the secondary side longitudinally wound coils 4A and 5A and the coil bobbin 2. However, since the width of the strip-shaped conductor plate constituting the secondary-side vertical coil 4A, 5A is narrower than the width of the strip-shaped conductor plate constituting the primary-side vertical coil 3, the secondary-side vertical coil 4A, 5A is E The size is just enough to contact the portion 1c (not shown) of the mold core 1b (does not interfere with the portion 1c of the E-type core 1b). At this time, when FIGS. 6A, 6B, and 6C are compared, the window area is constant in FIG. 6B in which the window area of a part of the secondary side longitudinally wound coils 4 and 5 is increased. Compared to FIG. 6A, the primary side leakage inductance can be increased by 0.6%. Further, in FIG. 6C in which the window area of all the secondary side longitudinally wound coils 4 and 5 is increased, the primary side leakage inductance is increased by 3.6% compared to FIG. 6A in which the window area is constant. be able to. Thus, as shown in the example of FIG. 6, the leakage inductor can be finely adjusted within a maximum range of 3.6% by changing the window area of the secondary side longitudinally wound coils 4 and 5.

  As described above, also in the third embodiment, the same effect as in the second embodiment described above can be obtained. Further, in the third embodiment, the length between the bendings of the strip-shaped conductor plate can be made variable. Since the window area for each turn of the coil through which the iron core central leg 1a penetrates (the cross-sectional area of the inner space of the cylindrical coil) is appropriately changed in the coil winding direction, between the coil and the iron core central leg. Can be appropriately changed in the coil winding direction, and the primary side leakage can be achieved by changing the coupling coefficient between the primary side vertical winding coil 3 and the secondary side vertical winding coils 4 and 5. Inductance (inductor value) can be adjusted.

  It should be noted that each of the first to third embodiments may be used independently for adjusting the leakage inductance of the primary-side longitudinally wound coil 3, but better, more finely using these in combination. Needless to say, it is possible to make an adjustment.

  Moreover, in said Embodiment 1-3, although the cross-sectional shape of the iron core center leg 1a of this invention was described about the thing with a quadrilateral shape, even if it is a triangle, a polygon, or a circle, the same effect Can be obtained. However, if the number of bends per one turn of the coil is large, the coil interval is increased and the iron core size is also increased. Therefore, the best case is that the iron core has a quadrilateral cross section and the coil is also constituted by a four-sided coil.

  1 Iron core, 1a Iron core center leg, 2 Coil bobbin, 3 Primary side vertical winding coil, 4 Secondary side vertical winding No. 1 coil, 5 secondary side vertical winding No. 2 coils, 6 iron core symmetry axis, 8 current conduction direction, 10 winding forming jig, 11 feed direction, 12 strip conductors, 12a, 12b, 12c, 12d, 12e, 12f portions (coil sides of the strip conductor 12), 13a , 13b, 13c, 13d, 13e Fold (folded portion of the strip-shaped conductor), 14 Strip-shaped conductor plate, 16-fold fold, 21 Strip-shaped conductor plate.

Claims (3)

An iron core central leg is provided in the central part, and the iron core that becomes the main magnetic flux path,
A high-frequency transformer comprising a cylindrical longitudinally wound coil wound spirally around the iron core central leg,
The coil constitutes an electromagnetically coupled primary coil and secondary coil,
The primary side coil and the secondary side coil are each formed of a continuous strip-shaped conductor plate having a substantially rectangular cross section,
The strip-shaped conductor plate has a spiral cylindrical longitudinally wound coil structure that is bent a plurality of times on the back side or the front side at an angle other than parallel and perpendicular to the current-carrying direction. Among these, the strip-like conductor plate is bent at the front side or the back side with respect to the direction of current flow at least once continuously, and is bent at the same side of the front side or the back side.   The primary side coil and the secondary side coil have a turn ratio of 1: n (n is a real number equal to or greater than 1), and the current density in the secondary side coil is the maximum in accordance with the turn ratio. The configuration is such that at least one value of the coil width or coil thickness of the primary side coil is equal to or greater than that of the secondary side coil until it becomes equal to the current density of the side coil. Item 2. The high frequency transformer according to Item 1.   3. The high-frequency transformer according to claim 2, wherein a length between folds of the belt-shaped conductor plate is variable, and a cross-sectional area of a cylindrical inner space of the coil is variable for each turn.

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