JP2019009177A - Magnetic coated wire and transformer using the same - Google Patents

Abstract

To provide a magnetic coated coil using a rectangular wire as winding, and a transformer which allows for compaction and high efficiency by suppressing a skin effect and a proximity effect effectively thereby reducing AC resistance.SOLUTION: A magnetic coated coil is provided with magnetic coating bodies on both lateral faces of a rectangular wire coil winding a rectangular wire in a coil form, corresponding to both lateral faces of the rectangular wire in a width direction, so as to shield the entire surface integrally. The rectangular wire coil 10 is an edgewise coil, an inner peripheral surface and an outer peripheral surface of the rectangular wire coil 10 are shielded entirely and integrally by the magnetic coating bodies 12, the rectangular wire coil is a flat winding coil of the rectangular wire, and both lateral faces of the rectangular wire coil are shielded entirely and integrally by the magnetic coating bodies.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a magnetically coated coil using a rectangular wire having a rectangular cross section and a transformer using the same.

Switching power supplies are used to supply stable DC power, and miniaturization and high efficiency are strongly desired. As an elemental technology for downsizing a converter used in a switching power supply, driving frequency can be increased. However, when the drive frequency is increased, the copper loss and iron loss generated in the transformer increase and the efficiency of the converter decreases.
Further, among the elements used in the converter, the insulating transformer has a larger volume than other elements, which causes an increase in circuit size. As a method for reducing the size of the transformer, there is a method using a planar transformer. The planar transformer uses a rectangular wire or a substrate pattern as a winding to improve the space factor of the coil, thereby realizing miniaturization. However, in the planar transformer, the cross-sectional shape of the winding is rectangular, so that the skin effect is noticeable compared to the round wire, and the distance between the windings becomes shorter as the coil space factor increases. There is a problem that the AC resistance due to the proximity effect increases.

  As a method for reducing the AC resistance due to the proximity effect, a magnetic coated wire (Patent Document 1) or a magnetic coated wire in which a magnetic composite material is coated on the outer surface of a conducting wire has been proposed (Patent Documents 2 to 4). Further, as a method for leveling the current density of the flat wire by suppressing the skin effect on the flat wire, there is a method of covering the end face of the flat wire with a magnetic material (Patent Document 5).

JP-A-4-214896 JP 2004-207443 A Japanese Patent Laid-Open No. 2005-20987 JP 2014-71969 A JP 2014-163828 A

  The present invention relates to a coil using a rectangular wire as a winding and a transformer using the coil, which reduces the AC resistance by effectively suppressing the skin effect and the proximity effect in a high-frequency region, thereby reducing the size of a switching power supply or the like. It is an object of the present invention to provide a magnetically coated coil and a transformer using the same, which can realize high efficiency and high efficiency.

The magnetic coated coil according to the present invention is integrally shielded on both sides corresponding to both side surfaces of the rectangular wire in the width direction of the rectangular wire coil in which the rectangular wire is wound in a coil shape. A magnetic coated coil provided with a magnetic coating.
As an example of the magnetically coated coil, the rectangular wire coil is an edgewise coil, and the entire inner peripheral surface and outer peripheral surface of the rectangular wire coil are integrally shielded by the magnetic covering, The flat wire coil is a flat wire coil of flat wire, and the entire surface of both sides of the flat wire coil is integrally shielded by the magnetic covering, the flat wire coil is a flat wire spiral shape. It is a coil and the both sides | surfaces of the width direction of the said flat wire are coat | covered with the said magnetic coating | coated body over the full length.
In addition, the meaning that the magnetic covering body is provided so as to integrally shield both side surfaces corresponding to both side surfaces in the width direction of the flat wire over the entire surface is as follows. This means that the entire side surface portion is provided so as to be integrally shielded, including the gap portion between the rectangular wires adjacent to the side surface.
These magnetically coated coils can be used as components of an air core reactor or an iron core reactor.

In addition, as the magnetic coated coil, a primary side coil and a secondary side coil, which are edgewise coils made of a rectangular wire, are arranged in an axial direction, and the rectangular wire of the primary side coil and the secondary side coil is arranged. The entire inner peripheral surface and outer peripheral surface corresponding to the side surfaces in the width direction are shielded integrally by the magnetic coating, and the end portions are located at positions where the primary side coil and the secondary side coil are partitioned. Are each provided with a magnetic plate as an arrangement connected to the inner magnetic cover and the outer magnetic cover.
Moreover, the primary side coil and the secondary side coil, which are flat winding coils made of a rectangular wire, are arranged concentrically on the inner peripheral side and the outer peripheral side, and the primary side coil and the secondary side coil, The entire surface of each side surface corresponding to the side surface in the width direction of the rectangular wire is integrally shielded by the magnetic covering, and the both end portions are at positions where the primary side coil and the secondary side coil are partitioned. A magnetic plate is provided as an arrangement connected to the magnetic covering that covers the side surfaces of the primary coil and the secondary coil.
A magnetic coated coil including the primary side coil and the secondary side coil can constitute a transformer by being incorporated in the core.

  According to the magnetic coated coil according to the present invention, the AC resistance can be effectively reduced, and particularly when the magnetic plate is provided in an arrangement for partitioning the primary side coil and the secondary side coil, AC resistance can be reduced effectively.

FIG. 2 is a plan view (a), a cross-sectional view taken along line A-A ′ (b), and a perspective view (c) showing the configuration of the magnetic coated coil according to the first embodiment. FIG. 4 is a plan view (a), a cross-sectional view taken along line A-A ′ (b), and a perspective view (c) showing a configuration of a magnetically coated coil according to a second embodiment. FIG. 7 is a plan view (a), a cross-sectional view taken along line A-A ′ (b), and a perspective view (c) showing a configuration of a third embodiment of a magnetic coated coil. FIG. 6A is a plan view showing a configuration example of a magnetic coated coil according to a fourth embodiment, FIG. 6B is a sectional view taken along line A-A ′, and FIG. FIG. 10 is a plan view (a), a cross-sectional view taken along line A-A ′ (b), and a perspective view (c) showing the configuration of the fifth embodiment of the magnetic coated coil. It is sectional drawing which shows the structure of the analysis model of a magnetic covering coil. It is a graph which shows the resistance-frequency characteristic calculated | required about the analysis model of FIG. It is a circuit structure figure of LLC resonance type converter. It is sectional drawing which shows the structure of the analysis model of a planar transformer. It is a graph which shows the thickness characteristic of the primary side resistance-magnetic coating | cover body when the secondary side of a planar transformer is open | released. It is a graph which shows the thickness characteristic of the primary side resistance-magnetic coating | cover when a secondary side of a planar transformer is short-circuited. It is an analysis figure which shows the magnetic flux density and magnetic flux line distribution of a planar transformer when a primary side coil and a secondary side coil are coat | covered with a magnetic coating body (secondary side short circuit). It is sectional drawing which shows the structure of the analysis model of the planar transformer equipped with the magnetic plate which partitions off between a primary side coil and a secondary side coil. 14 is a graph showing a primary side resistance-thickness characteristic of the magnetic covering when the secondary side of the planar transformer shown in FIG. 13 is open. It is a graph which shows the thickness characteristic of the primary side resistance-magnetic coating | cover when a secondary side of a planar transformer is short-circuited. It is an analysis figure which shows the magnetic flux density and magnetic flux line distribution of a planar transformer when a secondary side is short-circuited. It is an analysis figure which shows the magnetic flux density and magnetic flux line distribution of a planar transformer when a magnetic coating is provided only on the side surface of a coil and the secondary side is short-circuited. It is a graph which shows the coupling coefficient of a planar transformer-the thickness characteristic of a magnetic coating body.

(Configuration of magnetic coated coil)
<First Embodiment>
FIG. 1 shows a first embodiment of a magnetic coated coil according to the present invention. FIG. 1A is a plan view of a magnetic coated coil, FIG. 1B is a cross-sectional view taken along the line AA ′, and FIG. 1C is a perspective view. The flat wire coil 10 (coil constituted by a flat wire) is an edgewise coil (planar type) formed by winding a flat wire having a rectangular cross section so that the axial direction of the coil and the flat surface of the flat wire are perpendicular to each other. Coil).

The characteristic feature of the magnetic coated coil shown in FIG. 1 is that it comprises a structure in which the entire inner peripheral surface and outer peripheral surface of the rectangular wire coil 10 are integrally covered with a magnetic coating 12.
The flat wire coil 10 (edgewise coil) has a plurality of flat wires arranged at predetermined intervals in the axial direction. The magnetic covering 12 is provided so as to cover the entire inner peripheral surface and outer peripheral surface of the rectangular wire coil so as to shield the gap between the side surface and the rectangular wire adjacent in the stacking direction.

In FIG. 1 (a), the inner peripheral surface and the outer peripheral surface of the flat wire coil 10 are entirely covered with the magnetic coating 12, and the flat portion of the flat wire coil 10 is exposed.
In FIG. 1 (b), a magnetic covering 12 is provided so as to connect the side surfaces of the rectangular wires laminated in a plurality of stages, and the inner peripheral side portion and the outer peripheral side portion of the rectangular wire coil 10 are respectively magnetic. It shows that it is covered with the covering 12.

  As described above, when the inner peripheral side surface and the outer peripheral side surface of the flat wire coil 10 are entirely covered with the magnetic coating 12, the skin effect and the proximity effect generated when a high frequency is applied to the flat wire coil 10 are effectively suppressed. be able to. In particular, by providing the magnetic covering 12 so as to integrally connect the side surfaces of the adjacent rectangular wires, the effect of the proximity effect that acts on the adjacent rectangular wire to which the magnetic flux caused by the current flowing through the rectangular wire is effective is effective. Can be suppressed.

  The magnetic material used for the magnetic covering 12 is not particularly limited, and a magnetic material such as a commonly used ferrite (Mn-based or Ni-based) or amorphous alloy can be used. The magnetic covering 12 may be provided by, for example, using a sheet-like magnetic material so as to cover the inner peripheral surface and the outer peripheral surface of the flat wire coil 10, or a magnetic composite material made of magnetic powder and a binder may be used as a flat plate. It can also provide by the method of apply | coating to the internal peripheral surface and outer peripheral surface of the wire coil 10. FIG.

  The rectangular wire coil 10 shown in FIG. 1 is manufactured by spirally winding a rectangular wire, but instead of spirally winding, a rectangular wire unit of a form separated by a flat ring shape is used as a predetermined unit. It is also possible to form an edgewise rectangular coil by laminating at intervals and connecting the ends of the rectangular wires in series. Also in this case, similarly to the method described above, it is used as a magnetic coated coil that suppresses the skin effect and the proximity effect by covering the entire inner peripheral surface and outer peripheral surface of the flat wire coil with a magnetic coating. can do.

<Second Embodiment>
FIG. 2 shows a second embodiment of the magnetic coated coil.
The magnetic coated coil according to the present embodiment is a so-called flat-wound coil configured by winding rectangular wires so as to be laminated in the circumferential direction. Also in the present embodiment, the concept of covering the side surface of the rectangular wire coil 11 with the magnetic coating 12 is the same as that of the first embodiment.

As shown in FIG. 2 (b), in the flat wound coil, the flat wire is laminated in the direction perpendicular to the axis of the coil, so that the magnetic covering 12 is respectively formed on both side surfaces of the flat wire in the width direction. The rectangular wire coil 11 is integrally provided so as to shield the entire side surface portion.
FIG. 2A shows that the entire side surface portion (flat portion) in the width direction of the flat wire constituting the flat wire coil 11 is shielded by the magnetic coating 12. About the cylindrical inner peripheral surface and outer peripheral surface of the magnetic coated coil, the cylindrical surface of the rectangular coil 11 is exposed (FIG. 2 (c)).
In FIG. 2B, the end 12a of the magnetic covering 12 covering the side surface of the flat wire coil 11 is slightly bent and extended on the edge of the side surface of the flat wire. As for the shape of the end portion of the magnetic covering body 12, the end portion of the magnetic covering body 12 may be slightly extended from the edge of the flat wire, or may not be extended on the side surface of the flat wire. Anyway.

<Third Embodiment>
FIG. 3 shows a third embodiment of the magnetic coated coil.
The magnetic coated coil shown in FIG. 3 is formed by winding a rectangular wire with a spiral rectangular wire 13, that is, with the flat surface of the rectangular wire and the flat surface of the coil being the same plane.
In the present embodiment, as shown in FIG. 3 (b), the magnetic covering 12 is provided on both side surfaces in the width direction of the flat wire constituting the flat wire coil 13. The magnetic covering 12 covers both sides of the flat wire over the entire length of the flat wire constituting the flat wire coil 13.

For the magnetic coated coil composed of the spiral rectangular wire coil 13 as described above, the skin effect and the proximity effect when a high frequency is applied to the magnetic coated coil can be obtained by coating both sides of the rectangular wire with the magnetic coating 12. It is possible to suppress the AC resistance.
Also in the present embodiment, the end portion of the magnetic covering 12 that covers both sides of the flat wire may extend slightly from the edge of the flat wire onto the surface of the flat wire, or the side surface portion of the flat wire. Only the magnetic covering 12 may be coated. The action of suppressing the skin effect and the proximity effect is not significantly different between the case where the end of the magnetic covering 12 is extended on the surface of the flat wire and the case where the end is not extended.

<Fourth embodiment>
FIG. 4 shows a fourth embodiment of the magnetic coated coil. The magnetic coated coil of the present embodiment is an example configured as a magnetic coated coil used for a planar transformer.
As shown in FIG. 4B, the magnetic coated coil of the present embodiment is formed in a form in which the primary side coil 20 and the secondary side coil 21 are stacked with a common axis. The configurations of the primary side coil 20 and the secondary side coil 21 are the same as those of the magnetically coated coil described as the first embodiment. That is, the primary side coil 20 and the secondary side coil 21 are provided such that the entire inner peripheral surface and outer peripheral surface of the rectangular wire coil 10 are shielded by the magnetic covering 12.

One of the characteristic configurations of the magnetic coated coil according to the present embodiment is that the primary side coil 20 and the secondary side coil 21 are connected to each other, and the primary side and the secondary side are integrated with each other. It is the point covered by.
Another characteristic point is that, as shown in FIG. 4B, a magnetic plate 14 is provided in an arrangement that partitions the primary side coil 20 and the secondary side coil 21 from each other.

  The magnetic plate 14 is disposed so as to completely partition a planar region (planar ring-shaped region) through which the rectangular wire of the primary side coil 20 and the secondary side coil 21 passes. By arranging the magnetic plate 14 to divide the range through which the rectangular wire of the primary side coil 20 and the secondary side coil 21 passes, the inner peripheral edge of the magnetic plate 14 is connected to the inner magnetic cover 12, and the magnetic plate The outer peripheral edge 14 is connected to the outer peripheral magnetic covering 12. That is, the magnetic plate 14 divides the primary side coil 20 and the secondary side coil 21, and is provided in an arrangement for connecting the magnetic coverings 12 on the inner peripheral side and the outer peripheral side.

The magnetic plate 14 is also for guiding the magnetic flux into the magnetic plate 14 like the magnetic covering 12, and any material can be used as long as it is a magnetic material.
The magnetic coated coil of the present embodiment is formed in a planar shape in which a primary side coil 20 and a secondary side coil 21 are stacked, and the transformer can be reduced in size efficiently, and the magnetic coated body 12 and the magnetic coated coil can be reduced. Since the plate 14 is provided, the resistance value of the transformer in the high frequency region can be effectively reduced, and can be effectively used as a component part of the transformer having excellent characteristics.

<Fifth embodiment>
FIG. 5 shows a fifth embodiment of the magnetic coated coil.
Similarly to the fourth embodiment, the magnetic coated coil of the present embodiment is also used for being incorporated in a transformer.
The magnetic coated coil of the present embodiment is configured as a coil in which a flat wire is wound as described in the second embodiment as the primary side coil 20 and the secondary side coil 21. Moreover, the primary side coil 20 and the secondary side coil 21 are arrange | positioned concentrically, and the axis line is made common. In the present embodiment, the primary side coil 20 is arranged on the outside and the secondary side coil 21 is arranged on the inside. However, the arrangement of the primary side coil 20 and the secondary side coil 21 can be reversed. .

In the same manner as described in the second embodiment, the magnetic coated coil according to the present embodiment also covers both sides of the rectangular wire in the width direction of the primary coil 20 and the secondary coil 21 over the entire surface. Further, both side portions of the primary side coil 20 and the secondary side coil 21 are continuously and integrally covered with the magnetic coating 12.
Moreover, the magnetic plate 15 is arrange | positioned in the position which partitions off the primary side coil 20 and the secondary side coil 21 over the perimeter of the circumferential direction of a coil. The magnetic plate 15 is provided so that the end portion is connected to the magnetic covering 12 that covers both side portions of the primary side coil 20 and the secondary side coil 21.

  Even in the case of a transformer in which a flat wire coil of a rectangular wire is incorporated as a primary side coil and a secondary side coil, both sides of the coil are covered with the magnetic covering body 12, and the primary side and secondary side coils are separated from each other. By providing the magnetic plate 15, the resistance value of the transformer in the high frequency region can be effectively reduced, and a transformer having excellent characteristics can be configured.

(Characteristic analysis of magnetic coated coil)
As described in each of the embodiments described above, the magnetic coated coil according to the present invention is provided with a magnetic coating integrally on the entire side surface of the rectangular wire coil corresponding to both side surfaces in the width direction of the rectangular wire, In this configuration, the side surface portion of the flat wire coil is shielded by the magnetic coating.
In the following, first, the results of analyzing the resistance-frequency characteristics using analysis software for a magnetic coated coil in which a planar (edgewise) rectangular coil is provided with a magnetic coating will be described. The characteristics of the used planar transformer will be described.

FIG. 6 shows an analysis model of a magnetic coated coil whose frequency characteristics are analyzed using analysis software. This analysis model is provided with a magnetic covering so as to shield the entire inner peripheral surface and outer peripheral surface of a planar rectangular coil using a rectangular wire.
The flat wire has a width of 5 mm, a thickness of 0.1 mm, and a line distance of 0.05 mm. The number of turns of the coil was eight, and eight rectangular wires were connected in series. In FIG. 6, the coil is an axisymmetric model in which the zr plane is rotated once in the θ direction around the z axis.
In addition, the thickness t _c of the magnetic coating was set to t _c = 0.1 mm, 0.2 mm, and 0.3 mm, and the complex relative permeability μ ′ = 10 and μ ″ = 0 of the magnetic coating. The current was I = 1A _max, and the resistance was analyzed every 100 kHz in the frequency range of 1 Hz to 1 MHz.

FIG. 7 shows the results obtained by analyzing the resistance-frequency characteristics.
From FIG. 7, it can be seen that the resistance of the rectangular wire coil is reliably reduced by providing the magnetic coating as compared to the rectangular coil without the magnetic coating. The resistance value of a rectangular coil without a magnetic coating at a frequency of 1 MHz is 108.9 mΩ, while the resistance value is 88 mΩ with a magnetic coating, reducing the resistance by 19.2%. .
FIG. 7 also shows the result of analyzing a magnetic coated coil in which only the side surface of the coil is covered with a magnetic coating without bending the end of the magnetic coating into an L shape (With magnetic side plate). . The thickness of the magnetic coating is 0.1 mm. Also in this case, the effect of reducing the resistance value was clearly recognized as compared with the case where the magnetic coating was not provided.

In addition, in the frequency range of 100 kHz to 900 kHz, the effect of reducing the resistance was seen as the thickness of the magnetic coating was increased, but at 1 MHz, the resistance value did not depend on the thickness of the magnetic coating. Results were obtained.
The reason why the resistance value is no longer dependent on the thickness of the magnetic coating at a frequency of 1 MHz is that the current density increases at 1 MHz due to the skin effect, which increases the current density in the region near both ends of the flat wire. An action that suppresses the skin effect by providing a magnetic covering that becomes stronger compared to the case on the low frequency side, that is, the area where the current density is increased is brought close to the end of the flat wire in the width direction and the area becomes narrower. This is because the effect of suppressing the proximity effect appears more strongly.
In this analysis model, the end portion of the magnetic covering body is bent in an L shape by extending the end portion of the magnetic covering body on a flat rectangular plane (FIG. 6). Therefore, as the thickness of the magnetic covering increases, the extension length of the magnetic covering extending on the flat rectangular plane increases. If the range covering the flat surface of the rectangular wire becomes wider, it should act to suppress the skin effect more, but the resistance value does not change even if the thickness of the magnetic coating is changed. It means that the action of suppressing the proximity effect is mainly acting rather than the action of suppressing.

  In the analysis model of FIG. 6, the resistance-frequency characteristics are analyzed for a magnetic coated coil in which only the side surface of the flat wire coil is covered with the magnetic coating without extending the end of the magnetic coating on the flat surface of the flat wire. As a result, the resistance value at a frequency of 1 MHz was 101 mΩ. The result of this analysis shows that the contribution of the bent portion of the magnetic coating is about 12% at a frequency of 1 MHz, and the action of coating the flat surface of the rectangular wire with the magnetic coating reduces the resistance value by providing the magnetic coating. It can be seen that the effect is only a slight contribution.

(Characteristic analysis of transformer using magnetic coated coil)
In order to analyze the characteristics when a planar magnetic coated coil is incorporated in a transformer, an example of a transformer used in an LLC resonant converter circuit was analyzed using analysis software.
FIG. 8 shows an example of the circuit structure of the LLC resonant converter. The LLC resonant converter enables soft switching by resonating the leakage inductance of the transformer and the resonance capacitor. The coupling coefficient of the transformer is about 0.7 to 0.9, and in order to cause leakage inductance, the transformer primary coil and secondary coil are often divided and wound. Moreover, leakage flux is generated by providing a core gap. Therefore, an eddy current is generated when the leakage magnetic flux interlinks with the winding, and there is a problem that the AC resistance due to the proximity effect increases.

Table 1 shows the specifications of the LLC resonant converter. The input voltage is 380 V and the output voltage is 48 V. The inverter circuit assumes a full-bridge configuration using four FETs, and the transformer turns ratio is 8: 1. Since the coupling coefficient depends on the structure of the transformer, it was set to 0.7 to 0.9. The driving frequency is 1 MHz.

FIG. 9 shows an analysis model diagram of the planar transformer. In this analysis, a two-dimensional analysis was performed with the cross section of the core as an axisymmetric model. The flat wire had a width of 5 mm, a thickness of 0.1 mm, and a line distance of 0.05 mm. The number of turns of the primary coil is 8 and the 8 rectangular wires are connected in series. The number of turns of the secondary coil was 1, and 8 coils were connected in parallel. The primary side coil and the secondary side coil are of a type in which the inner peripheral diameter and the outer peripheral diameter are made to coincide with each other and overlapped as shown in FIG.
A gap of 0.35 mm was provided between the primary side coil and the secondary side coil. A gap was provided in the center leg of the core, and the gap length of the core was 2 mm.

The magnetic covering is assumed to be mounted in such a manner as to integrally shield the inner peripheral surface and the outer peripheral surface of the primary side coil and the secondary side coil. The thickness t _c of the magnetic coating was analyzed with t _c = 0.1 mm, 0.2 mm, and 0.3 mm, as in the analysis of the magnetic coated coil.
Resistance when the complex relative permeability of the magnetic coating is μ '= 10, μ''= 0, current of frequency 1 MHz, I = 1 Amax is passed through the primary coil, and the secondary coil is opened or short-circuited The coupling coefficient of inductance and transformer was analyzed. The resistance when the secondary side is short-circuited is used to simulate the magnetic flux distribution in the driving state.
Note that the end of the magnetic covering was bent into an L shape and slightly extended from the edge of the flat wire to the surface of the flat wire.

FIG. 10 is a graph showing the primary side resistance-thickness characteristic of the magnetic coating when the secondary side of the planar transformer using the magnetic coated coil is opened. The horizontal axis in FIG. 10 is the thickness t _c of the magnetic coating.
Compared with a transformer with a primary coil and a secondary coil without a magnetic coating, the transformer with a coil with a magnetic coating reduced the resistance by a maximum of 7.4%. This is because the magnetic flux interlinked with the end portion of the rectangular wire is reduced by providing the magnetic covering as in the case of the magnetic covered wire coil.

FIG. 11 is a graph showing a primary side resistance-thickness characteristic of the magnetic coating when the secondary side of the planar transformer using the magnetic coated coil is short-circuited. Compared with a transformer using a coil without a magnetic coating, the transformer using a coil with a magnetic coating increased the resistance by a maximum of 24.7%.
Fig. 12 shows the magnetic flux density and magnetic flux distribution of the planar transformer when the primary and secondary coils are covered with a magnetic coating (secondary short circuit, t _c = 0.1 mm, I = 1 Amax, f = 1 MHz) ). From FIG. 12, it can be seen that the magnetic flux concentrates at an intermediate position between the primary side coil and the secondary side coil. By providing the magnetic covering so as to shield the side surfaces of the primary side coil and the secondary side coil, the magnetic flux flows so as to connect the inner and outer peripheral magnetic coverings. It is considered that the eddy current is generated by the magnetic flux between the magnetic coatings passing through the rectangular wire, and the resistance is increased.

FIG. 13 shows an analysis model of a planar transformer in which a magnetic plate is arranged so as to partition between a primary side coil and a secondary side coil incorporated in the planar transformer as a method for solving the above-described problems.
The analysis was performed under the conditions where the thickness of the magnetic plate was t _g and t _g = 0.1 mm, 0.2 mm, and 0.3 mm.

FIG. 14 shows the primary resistance-magnetic coating thickness when the secondary side is opened for a transformer (FIG. 13) incorporating a primary coil and a secondary coil provided with a magnetic coating and a magnetic plate. Show properties.
In FIG. 14, the resistance value was the smallest when t _c = 0.2 mm and t _g = 0.3 mm, and the resistance value at that time was 215 mΩ. The resistance value of the transformer without using the magnetic coating and the magnetic plate was 272 mΩ, and the resistance value was reduced by 21% by using the magnetic coating and the magnetic plate.

FIG. 15 shows the primary side resistance-thickness characteristic of the magnetic coating when the secondary side of the transformer is short-circuited. In FIG. 15, the resistance value is the smallest when t _c = 0.1 mm and t _g = 0.3 mm, and the resistance value at that time is 192 mΩ. The resistance value of the transformer without using the magnetic coating and the magnetic plate was 299 mΩ, and the resistance value was reduced by 35.8% by using the magnetic coating and the magnetic plate.

FIG. 16 shows the magnetic flux density and magnetic flux line distribution of the planar transformer (secondary short circuit, t _c = 0.1 mm, t _g = 0.3 mm, I = 1 Amax, f = 1 MHz).
By providing the magnetic covering and the magnetic plate, the magnetic flux passing through the rectangular wire is reduced compared to the case where the magnetic plate shown in FIG. I understand that.

The analysis results shown in FIGS. 15 and 16 show that the ends of the magnetic covering provided on the primary coil and the secondary coil are bent in an L shape, and the magnetic covering is slightly extended at the edge of the flat wire. It is made into the form made to do. The case where the magnetic coating was provided only on the side surface of the coil was also analyzed, and the resistance value at that time was shown as (t _g = 0.3 mm, side plate t _c = 0.1 mm) in FIG. FIG. 17 shows the magnetic flux density and magnetic flux line distribution (secondary short circuit, t _c = 0.1 mm, t _g = 0.3 mm, I = 1 Amax, f = 1 MHz).
The values shown in FIG. 15 are obtained when the resistance value is the smallest (t _c = 0.1 mm, t _g = 0.3 mm). The resistance value is 195 mΩ, and the end of the magnetic coating is on the rectangular wire. It was slightly larger than when it was extended.

Moreover, the analysis result about the magnetic flux line distribution shown in FIG. 17 is almost the same as the analysis result shown in FIG. From this result, it can be seen that even if the magnetic covering is provided only on the side surface portion of the coil, the effect of suppressing the proximity effect is functioning together with the effect of providing the magnetic plate.
In addition, these analysis results show that, as a method of reducing the AC resistance of the planar transformer, the AC resistance due to the proximity effect can be reduced by arranging a magnetic body in a region where the magnetic flux around the winding is concentrated. Suggest that you can.

FIG. 18 shows the coupling coefficient of the planar transformer-the thickness characteristic of the magnetic coating. From FIG. 18, it can be seen that the coupling coefficient increases slightly when the thickness (t _c ) of the magnetic coating is increased, while the coupling coefficient decreases when the thickness (t _g ) of the magnetic plate is increased. From the analysis results described above, the resistance values were the smallest when t _c = 0.1 mm and t _g = 0.3 mm, and the coupling coefficient at that time was 0.76. This coupling coefficient satisfies the target coupling coefficient of 0.7 to 0.9 when a planar transformer is used in an LLC resonant converter, and a planar transformer using a magnetic coating and a magnetic plate is used for an LLC resonant converter. It can be preferably used.

  The above-mentioned analysis results for the planar transformer show that the side surfaces of the primary side coil and the secondary side coil are magnetically coated over the entire surface as a method of reducing the resistance of the transformer including the primary side coil and the secondary side coil made of a rectangular wire coil. It shows that a configuration in which a magnetic plate is provided so as to be shielded by the body and a magnetic plate is provided so as to partition the primary side coil and the secondary side coil is shown. The primary side coil and the secondary side coil may be the above-described planar type coil (edgewise coil) or a flat coil. In the case of a flat winding coil in which the primary side and secondary side coils are wound concentrically, a method of arranging a magnetic plate so as to partition the primary side and secondary side coils is effective.

10, 11, 13 Rectangular coil 12 Magnetic covering 12a End of magnetic covering 14, 15 Magnetic plate 20 Primary coil 21 Secondary coil

Claims (9)

  A magnetic covering is provided on both sides corresponding to both sides of the rectangular wire in the width direction of the rectangular wire coil in which the rectangular wire is wound in a coil shape so as to be integrally shielded. Magnetic coated coil characterized by The rectangular coil is an edgewise coil;
The magnetic coated coil according to claim 1, wherein the entire inner peripheral surface and outer peripheral surface of the rectangular wire coil are integrally shielded by the magnetic coating. The flat wire coil is a flat wire coil of flat wire,
2. The magnetic coated coil according to claim 1, wherein the entire surface of both sides of the flat wire coil is integrally shielded by the magnetic coating. The flat wire coil is a flat wire spiral coil,
2. The magnetic coated coil according to claim 1, wherein both sides of the flat wire in the width direction are covered with the magnetic coating over the entire length. The primary side coil and the secondary side coil, which are edgewise coils made of flat wires, are arranged in a stacked manner in the axial direction,
The entire inner peripheral surface and outer peripheral surface of the primary coil and the secondary coil corresponding to the side surfaces of the rectangular wire in the width direction are integrally shielded by the magnetic covering,
A magnetic plate is provided at a position for partitioning the primary side coil and the secondary side coil so that both ends are connected to the inner peripheral side magnetic covering and the outer peripheral side magnetic covering, respectively. Magnetic coated coil. A primary coil and a secondary coil, which are flat winding coils made of flat wires, are arranged concentrically on the inner peripheral side and the outer peripheral side,
The entire surfaces of both side surfaces of the primary coil and the secondary coil corresponding to the side surfaces of the rectangular wire in the width direction are integrally shielded by the magnetic covering,
A magnetic plate is provided as an arrangement in which both ends are connected to the magnetic coating covering the side surfaces of the primary coil and the secondary coil, respectively, at a position separating the primary coil and the secondary coil. Characteristic magnetic coated coil.   The magnetic coated coil according to any one of claims 1 to 6, wherein an end portion of the magnetic covering body extends in an edge portion of the rectangular wire.   An iron core reactor in which the magnetically coated coil according to any one of claims 1 to 4 is incorporated. A transformer in which the magnetically coated coil according to claim 5 is incorporated in a core.

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