JP2003197438A - Magnetic element and power supply using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a miniaturized and thin magnetic element of low loss and a power supply, which reduce loss due to eddy current and also reduce loss due to DC resistance. <P>SOLUTION: The magnetic element can be provided by making a conductor width in an outermost circumference of a coil 4, incorporated in a magnetic element having width larger than that of a conductor in an innermost circumference. Or the magnetic element can be also provided by making the coil 4 comprise a plurality of division conductors in mutual parallel connection. The power supply can be provided by using the magnetic element. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small, thin and low-loss magnetic element used in a switching power supply device or the like for supplying stabilized DC power to industrial and consumer electronic devices, and its magnetic property. The present invention relates to a power source using an element.

[0002]

2. Description of the Related Art In recent years, with the miniaturization, thinning, high performance, and energy saving of electronic devices, magnetic elements used in these devices are strongly demanded to be smaller, thinner, and have lower loss. Has been. There are two main types of loss that occur in magnetic elements: iron loss and copper loss. Copper loss is
Iron loss is a loss mainly caused by the DC resistance component of the coil included in the magnetic element, and iron loss is a loss mainly caused by the eddy current generated in the magnetic body and the coil included in the magnetic element. Therefore, in order to reduce the loss of the magnetic element, it is necessary to consider the reduction of both the loss due to the resistance of these coils and the loss due to the eddy current.

An example of the structure of a conventional magnetic element will be described below.

First, FIG. 1 is a cross-sectional view of a magnetic element having a coil made of a wire having a uniform width in a radial direction from a coil central axis.
3 shows. In the example of FIG. 13, the flat plate-shaped magnetic body 21 is laminated on both surfaces of the flat plate-shaped coil 24 in order to increase the inductance of the element. With such a configuration of the magnetic element, a small and thin magnetic element can be easily realized with high accuracy. Further, in order to further increase the inductance of the element, as shown in FIG. 13, a magnetic body may be embedded in the portions corresponding to the magnetic core 22 and the outer legs 23. Such a configuration is disclosed in, for example, Japanese Patent Laid-Open No.
It is disclosed in Japanese Patent Publication No. 001-85421.

Next, FIGS. 14 and 15 are sectional views of a magnetic element (disclosed in Japanese Patent Laid-Open No. 11-40438) in which the width of the conductor wire of the coil is changed in the radial direction from the central axis of the coil. The shape of the coil 24 is different from the example of FIG. 13, and the resistance loss in the high frequency region is reduced by changing the conductor wire width of the coil according to the strength of the magnetic flux interlinking the portion. In addition, this magnetic element can reduce loss due to eddy current at the same time. Since the eddy current is generated in the coil by the magnetic flux that links the coil, by making the coil wire width relatively narrow in the area where the magnetic flux that links is strong (near the innermost circumference and the outermost circumference of the coil), This is because the occurrence can be reduced. In the example of FIG. 14, the conducting wire width of the coil at the innermost circumference for several turns and at the outermost circumference is narrowed. In the example of FIG. 15, the conductor wire width of the coil is reduced from the innermost circumference to several turns and from the outermost circumference to several turns.

[0006]

However, in a magnetic element having a coil made of a wire having a uniform width as described above, most of the magnetic flux leaked from the magnetic core passes through the coil in the vicinity of the innermost circumference, so that the eddy current causes There was a problem of loss. In particular, for magnetic elements aiming to be small and thin, it is necessary to secure a sufficient cross-sectional area at the center of the coil in order to secure the required width of the coil conductor and to maintain characteristics such as inductance, DC resistance, and DC superposition characteristics. difficult. Therefore, the degree to which the magnetic flux that cannot pass through the central portion leaks to the outside becomes stronger. In addition, the amount of leakage magnetic flux also increases when a low magnetic permeability material is used for the magnetic body placed in the center of the coil or when a gap is provided. The loss due to the eddy current due to such leakage magnetic flux becomes larger as the width of the conductor wire of the coil becomes wider in order to cope with downsizing and thinning. Also, the loss due to eddy current is
The higher the frequency of the current flowing through the coil, the larger the current. Therefore, when a magnetic element intended to be small and thin is used for a power source for high frequency switching, the loss is increased and the overall efficiency is reduced.

On the other hand, in the magnetic element disclosed in Japanese Patent Laid-Open No. 11-40438, the width of the conductor wire of the coil is changed in consideration of only the strength of the magnetic flux linking the coil, and the eddy current as described above causes The loss can be reduced. However, this method also reduces the loss due to the eddy current because the conductor width of the coil in the outer peripheral portion having a long circumference is narrowed, but there is a problem that the overall DC resistance increases. In particular, in the case of a magnetic element mainly used for passing a direct current, such as a power supply device, this increase in direct current resistance is a major factor of loss, and it is difficult to achieve the purpose of obtaining a low loss magnetic element.

[0008]

In order to solve the above-mentioned problems, a magnetic element of the present invention is a magnetic element including a coil, in which the outermost conductor width of the coil is smaller than the innermost conductor width. It is characterized by being wide.

In the above magnetic element, it is preferable that the outermost circumference of the coil has a maximum width of the conductor wire of the coil. Since the circumference of the outermost circumference is the longest among the conductive wires of the coil, the loss due to the resistance of the coil can be more effectively reduced by maximizing the width of the outermost conductive wire.

In any of the above magnetic elements, the coil wire width may be gradually changed from the innermost circumference to the outermost circumference, or may be changed stepwise. Absent.

The magnetic element of the present invention is a magnetic element including a coil, wherein the conducting wire of the coil includes a plurality of divided conducting wires connected in parallel with each other. Further, it is preferable that the conductor wire of the coil characterized in that the conductor wire width of the outermost circumference is wider than the conductor wire width of the innermost circumference includes a plurality of divided conductor wires connected in parallel with each other. Here, the split conducting wire is a portion obtained by splitting the conducting wire of the coil into a plurality of slits or the like, and the conducting wire of the coil is formed by connecting the plurality of split conducting wires in parallel. The divided conductors connected in parallel form the same circumference of the coil. For example, FIG. 4 or FIG.
8 corresponds to this divided conductor, and the conductor 7 is formed by connecting in parallel. Thus, by dividing the conductor wire of the coil, it is possible to reduce the loss due to the eddy current and the loss due to the resistance at the same time. Also,
It is possible to further reduce the loss due to the eddy current by twisting the divided conductors connected in parallel by twisting or the like.

In any one of the above magnetic elements, it is preferable that the outermost conductor of the coil includes a plurality of divided conductors connected in parallel with each other. Further, it is preferable that the innermost conductor of the coil includes a plurality of divided conductors connected in parallel with each other. Since the magnetic flux that links the coils is strong at the outermost circumference and the innermost circumference of the coil, the loss due to the eddy current can be further reduced by including such a structure.
Further, it is particularly effective when the conductor width of the outermost circumference of the coil is increased for the purpose of reducing the resistance of the coil.

In any one of the above magnetic elements, it is preferable that the number of divided conducting wires connected in parallel is as large as the conducting wire on the outer circumference of the coil.

In any of the above magnetic elements, it is preferable that the divided conductors connected in parallel have the same width.

In any one of the above magnetic elements, it is preferable that the width of the gap between the divided conducting wires is equal to or less than the width of the gap between the conducting wires.

In any of the above magnetic elements, the coil is preferably flat. If it is flat, the magnetic element can be made small and thin.

In any one of the above magnetic elements, it is preferable that the coil is formed by using at least one layer of a coil pattern formed on the printed board.
Further, in the above magnetic element, the coil pattern is preferably a coil pattern obtained by using a spiral slit.

In any of the above magnetic elements, it is preferable that the coil is made of a rectangular copper wire.
Further, in the above magnetic element, it is preferable that the coil is formed by winding a rectangular copper wire around a magnetic body serving as a magnetic core.

In any of the above magnetic elements, the coil is preferably formed by using a solenoid coil.

It is preferable that any one of the magnetic elements described above includes a plurality of coils, and the coils are magnetically coupled to each other.

In any of the above magnetic elements, it is preferable that the first magnetic body is laminated in the plane direction of the coil. Further, it is preferable that the first magnetic body has a flat plate shape. In any of the above magnetic elements, it is preferable to include a structure in which a second magnetic body is arranged on at least one of the center and the outer circumference of the coil. The first magnetic body and the second magnetic body may be made of the same material, or may be integrated as necessary.

The power supply of the present invention is characterized by including any one of the above magnetic elements.

The magnetic element described above can reduce the loss due to the eddy current generated in the coil in the vicinity of the innermost circumference and at the same time reduce the loss due to the DC resistance of the coil. As a result, it is possible to provide a magnetic element that is small, thin, and has low loss. Further, by using these magnetic elements, a compact and highly efficient power source can be provided.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) Embodiment 1 of the present invention will be described with reference to FIGS.

1 to 3 are cross-sectional views showing an example of the magnetic element according to the present embodiment in the radial direction from the coil central axis. The flat plate-shaped magnetic body 1 is laminated on both sides of the coil 4,
Magnetic bodies are arranged in the magnetic core 2 which is the center of the innermost circumference of the coil and the outer foot 3 which is the outer circumference of the outermost circumference of the coil. The coil 4 is composed of upper and lower two layers connected to each other, and has a total of 14 turns. FIG.
The configuration is the same as the conventional example shown in FIG. 15 except for the coil 4.

As shown in FIGS. 1 to 3, in the coil 4, unlike the conventional example, the wire width of the coil in each circumference gradually becomes wider from the inner circumference to the outer circumference, and is wider than the innermost circumference wire width. It features a structure in which the width of the outermost conductor wire is wide.

In other words, the conductor wire widths of the coils in each circumference are W ₁ , W ₂ , ..., W _n-1 , W _n , in order from the innermost circumference.
, W _p (n: integer of 2 to _p , W _n > 0, W _p : conductor width of outermost circumference of coil), W _n-1 ≦ W _n , and W ₁ <W _p
It means that the relationship should be established. Further, at this time, even if the direction of the inequality sign of W _n-1 ≦ W _n is partially reversed, the increase in the DC resistance value caused by the difference is slight, and the overall inner conductor width is Any coil may be used as long as it is narrow and has a wide outer conductor wire.

Above all, the wire width W of the outermost circumference of the coil
It is preferable that _p is the maximum as compared with the conductor width of the other circumference of the coil. This is because the outermost circumference of the conductor of the coil is the longest.

In the magnetic element according to the present embodiment, the coil 4 may have such characteristics. With the coil having such characteristics, unlike the conventional example shown in FIGS. 14 and 15, it is possible to simultaneously reduce the loss due to the eddy current and the loss due to the DC resistance.

For example, in order to realize the above structure, in the example of FIG. 1, the coil conducting wire in each circumference is designed to have a width proportional to the radius from the central axis. This may be a coil having a conductive wire width proportional to the square of the radius as shown in FIG. 2 or a coil having a conductive wire width divided into three stages as shown in FIG. Absent. As described above, the width of the conductor wire of the coil may be increased stepwise or uniformly from the innermost circumference to the outermost circumference.

The coil is not particularly limited, but a coil formed in a flat plate shape is preferable in order to make the coil small and thin. As the coil formed in a flat plate shape, for example, a coil pattern on a printed circuit board or the like can be used. Such a coil pattern can be obtained by using a spiral slit.

In addition, as the coil, it is also possible to use an ordinary rectangular copper wire or a round copper wire in the form of a coil, which is obtained by a process such as etching or plating growth capable of arbitrarily controlling the width of the conductor of the coil. A coil can also be used.

The number of turns of the coil 4 is as shown in FIGS.
It is not limited to 14 shown in FIG. It can be set arbitrarily according to the required magnetic characteristics.

Further, although the coil 4 has a structure of upper and lower two layers in FIGS. 1 to 3, even if it is a single layer, it is a plurality of layers of three layers or more if the respective coil layers are connected. It doesn't matter. The number of layers can be set arbitrarily according to the required magnetic properties. The connection method may be serial or parallel.

Although only the coil 4 can be used as a magnetic element, as shown in FIGS.
Are preferably laminated, and the magnetic core 2 and the outer foot 3 are
It is preferable that the magnetic substance is also arranged in the portion. The shape of the magnetic body 1 is not limited as long as a desired magnetic path can be secured, but for a small and thin magnetic element, the shape shown in FIG.
~ A flat plate shape as shown in Fig. 3 is preferable.

The magnetic material 1 is not particularly limited,
Of these, it is preferable to use ferrite. Moreover, the magnetic body disposed on the magnetic core 2 and the outer foot 3 is not particularly limited, but it is preferable to use a composite magnetic material such as a dust core material. The first magnetic body and the second magnetic body may use the same material,
It may be integrated as needed.

Table 1 below shows the results of characteristic comparison between the magnetic elements shown in FIGS. 1 to 3 in the present embodiment and the magnetic elements shown in FIGS. 13 to 15 which are conventional examples. As a characteristic,
The inductance, the AC resistance that is a parameter reflecting the loss due to the eddy current, and the DC resistance were calculated using the finite element method. The AC resistance used was 1 MHz. 1 to 3 correspond to Examples 1 to 3, and FIGS. 13 to 15 correspond to Comparative Examples 1 to 3. Further, as Example 4, a coil in which the change in the conductor width is partially reversed between the innermost circumference and the outermost circumference of the coil shown in FIG. 1 (the coil width on the third and fourth laps counted from the innermost circumference) Inversion: the above condition of W _n-1 ≧ W _n ) was used.

The characteristic analysis based on the finite element method was performed using the parameters shown in Tables 2 and 3 below. In Table 2,
The conductor width of each circumference of the coil used as an Example and a comparative example is shown. “2T”, “3T”, etc. in Table 2 are the second turn (second turn) and 3 from the innermost circumference of the coil, respectively.
It means that it is the turn (third lap). Although the number of turns of each coil shown in Table 2 is 7, two layers were laminated in series to make a model with 14 turns. Further, as shown in Table 3, the coils used in Examples and Comparative Examples were assumed to have the same innermost diameter, outermost diameter, thickness, and material, and all magnetic materials were also assumed to be the same material. In the column showing the magnetic material in Table 3, "A
“Part” means a part corresponding to the magnetic body 1 shown in FIGS. 1 to 3 and the magnetic body 21 shown in FIGS.
The “B portion” is a portion corresponding to the magnetic core 2 and the outer foot 3 shown in FIGS. 1 to 3 and the magnetic core 22 and the outer foot 23 shown in FIGS. 13 to 15.

In each of the examples and comparative examples, a model was used in which the cross-sectional views shown in FIGS. 1 to 3 and 13 to 15 were rotated once around the central axis.

[0041]   (Table 1) ――――――――――――――――――――――――――――――――――――             AC resistance (1MHz) DC resistance Inductance correspondence diagram                (MΩ) (mΩ) (μH) ―――――――――――――――――――――――――――――――――――― Example 1 521 184 4.96 FIG. Example 2 388 197 4.84 Example 3 401 204 4.82 Example 4 535 184 4.94 Figure 1: Partial reversal. ―――――――――――――――――――――――――――――――――――― Comparative Example 1 742 192 4.94 Comparative Example 2 583 230 4.88 Comparative Example 3 893 270 4.91 FIG. ――――――――――――――――――――――――――――――――――――

[0042]

[Table 2]

[0043]

[Table 3]

According to the results of Table 1, it can be said that the inductances are substantially the same in both the example and the comparative example. However, in Example 1 in which the conductor width of the outer peripheral portion having a longer circumferential length than that of the inner periphery is relatively widened, loss due to eddy current is reduced as compared to Comparative Example 1 in which a conductor wire of equal width is used over the entire circumference. It can be seen that loss reduction due to DC resistance was achieved at the same time. It can be seen that in Examples 2 and 3, the DC resistance was slightly increased as compared with Example 1, but the AC resistance was significantly decreased.
Further, compared with Comparative Example 2 and Comparative Example 3 which have a structure in which the conductor width of the outer circumference of the coil is narrowed to reduce the AC resistance, the AC resistance is further greatly reduced and the effect of reducing the DC resistance is sufficient. Can be said to be large.

Further, it can be seen that also in Example 4, which has a structure in which the change in the conductor width of some coils is reversed, both the AC resistance and the DC resistance can be reduced as compared with the comparative example.

In the above-mentioned Examples and Comparative Examples, the flat magnetic material was laminated on both sides of the coil, and the magnetic material also existed in the magnetic core and the outer leg. Even when it is larger, it is possible to obtain both effects of reduction of loss due to eddy current and reduction of loss due to DC resistance, and it is possible to achieve synergistic reduction of loss. When the interlinkage magnetic flux is large, when only the coil is present, magnetic materials are laminated on both sides of the coil, but when the magnetic core is an air core, use a magnetic material with high magnetic permeability for the magnetic core or the outer foot. If there is a gap,
It is conceivable that the magnetic core or the outer leg is made of a material having a lower magnetic permeability than the magnetic material on both sides of the coil, although there is no gap.

In the above-mentioned Examples and Comparative Examples, a model in which the whole shape is a disk shape was considered and compared.
Any shape, such as a circle, an ellipse, and a quadrangle, that can be used to form the coil can obtain the same effect.

Further, it is most preferable that the conducting wire in all directions viewed from the center is a coil having the above-mentioned characteristic, but the effect of the present invention can be obtained even when the above-mentioned characteristic is not partially satisfied due to the shape of the magnetic element. Obtainable.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings.

4 to 6 are schematic views showing an example of the magnetic element according to the present embodiment. As shown in FIGS. 4 to 6, in the magnetic element of the present embodiment, a spiral coil 4 is arranged around the magnetic core 2, and the conductor wire 7 of the coil 4 is divided into a plurality of divided parts. It is characterized in that the conductor 8 includes a divided structure.

Here, the divided conducting wire means each portion obtained by dividing the conducting wire of the coil into a plurality of slits or the like. As shown in FIGS. 4 to 6, a plurality of divided conducting wires 8 are connected in parallel to form a conducting wire 7,
The divided conducting wires 8 connected in parallel form the same circumference of the coil. In order to obtain such a divided structure, a slit or the like may be provided on the conducting wire. On the contrary, a plurality of independent conducting wires may be connected in parallel as divided conducting wires, and the aggregate may function as one large conducting wire. Furthermore, by making the split conducting wires connected in parallel into a spiral shape by applying a twist or the like, it is possible to further reduce the loss due to the eddy current.

The width of the conductor wire of the coil in the portion provided with the split structure in this manner can be the sum of the widths of the split conductor wires orthogonal to the magnetic flux.

By using the coil having the above divided structure, it is possible to obtain the magnetic element in which the loss due to the eddy current is simultaneously reduced without increasing the loss due to the DC resistance.

For example, as shown in FIG. 6, when the divided structure of the present invention is applied to the outermost circumference and the innermost circumference of a coil whose conductor widths are equal, the conventional equal width conductor shown in FIG. The loss due to the eddy current can be effectively reduced as compared with the coil.

Further, in the example of FIG. 6, unlike the conventional example shown in FIGS. 14 and 15, the eddy current is not provided by reducing the conductor width of the coil according to the strength of the interlinkage magnetic flux, but by providing a divided structure. The loss due to for that reason,
It is possible to secure the conductor wire widths of the innermost circumference and outermost circumference of the coil equivalently at the minimum required, and it is possible to overcome the disadvantage that the DC resistance value increases due to the reduction of the conductor wire width, which was seen in the conventional example. Becomes

In this case, in the divided structure, since the magnetic flux interlinking the coils is particularly strong at the outermost and innermost circumferences of the coil, the innermost or outermost circumference of the coil or, if necessary, the innermost and outermost circumferences. It should be provided at the same time. Also,
Although it is preferable to provide the divided structure over the entire circumference, it is possible to obtain the effect of the present invention by providing the divided structure at least at a part of the circumference.

If necessary, the coil may be separated from the outermost circumference by 2
It is also possible to provide a split structure for the conductor wire from the innermost circumference to the second circumference up to the circumference.

Further, such a split structure can be introduced to a coil having a wider conductor width toward the outer periphery, similar to the coil shown in the first embodiment. An example of this is shown in FIG.
And shown in FIG. In the example shown in FIGS. 4 and 5, a split structure is provided in the coil 4 having a wider conductor width toward the outer circumference. With the coil having such a configuration, both losses due to the eddy current and the DC resistance can be more effectively reduced.

The divided structure may be provided over the entire circumference or a part of the circumference. Above all, it is more effective to provide the divided structure on the innermost circumference where the magnetic flux interlinks the coil is large or on the outer circumference of the coil 4 where the conductor width of the coil is relatively wide. Further, it is particularly preferable to provide the outermost circumference. This is because the outermost circumference has the longest circumference and it is necessary to widen the conductive wire width in order to reduce the loss due to resistance, and since the magnetic flux linking the coils is large, the effect of introducing the split structure is great. Further, since the width of the conductor wire of the coil becomes wider toward the outer circumference, it is preferable that the number of the divided conductor wires 8 is larger toward the outer circumference as shown in FIG.

In addition, the same effect can be obtained for a coil having a conductor wire width tendency other than the above.

In the present embodiment, it is preferable that the split conducting wires 8 have the same width. When they are equal to each other, the effect of the present invention can be obtained most.

Further, since there is no problem even if the divided conducting wires 8 are partially conductive, it is preferable that the width of the gap 5 between the divided conducting wires is equal to or less than the width of the gap 6 between the conducting wires. When such a structure is used, the reduction in the cross-sectional area of the coil can be minimized, and the increase in DC resistance due to the existence of the divided structure can be reduced.

Although FIGS. 4 to 6 show the magnetic body only in the magnetic core of the coil 4, like the coil in the first embodiment, the magnetic body is provided in the outer peripheral portion of the coil or in the plane direction of the coil. If so, the characteristics can be further improved. In addition, even when the magnetic flux linking the coils is larger, it is possible to obtain both effects of reduction of loss due to eddy current and reduction of loss due to DC resistance, and it is possible to achieve synergistic reduction of loss. As in the first embodiment, the effect of the present invention does not depend on the shape of the coil, so any shape may be used as long as it is possible to form the coil.

(Third Embodiment) A third embodiment of the present invention will be described below with reference to the drawings.

FIG. 7 is a sectional view showing an example of the choke coil according to the present embodiment. As shown in FIG. 7, the choke coil is one type of magnetic element including a structure in which the coil 4 is wound around the magnetic core 2.

At this time, if the coil 4 is the same as in the first and second embodiments, it is possible to obtain a low-loss choke coil in which both the loss due to the eddy current and the loss due to the DC resistance are reduced. . In the case of the choke coil, it is important to reduce the loss due to the DC resistance, and the effect of using the coil 4 in the present invention is particularly large.

Because the choke coil is generally used for rectification and smoothing in an electric circuit, the flowing current is a direct current superimposed current, and the ratio of the direct current component is occupied except when the load is extremely light. Get higher Therefore, when considering the effective value of the current flowing through the coil, the ratio of the AC component is small and the DC component occupies the majority, and the DC resistance loss is dominant in the loss generated in the coil.

Since the coil having the reduced loss can suppress the heat generation of the element, it is not necessary to use an insulating material having a high heat resistance and a highly efficient heat radiating means which are generally expensive. Thus, it becomes possible to provide a thin device at low cost.

Further, in the magnetic element according to the present embodiment, it is preferable that the coil is formed by using a rectangular copper wire. This is because when a rectangular copper wire is used, the cross-sectional area of the coil conductor wire is large, so that it is possible to handle a large current that cannot be flowed by a flat coil. FIG. 8 shows an example of a choke coil having a coil made of flat copper wire. A coil 4 constituted by using a rectangular copper wire is wound around the magnetic core 2.

The structure shown in FIG. 8 can be obtained by using the method shown in FIG. 9, for example. As shown in FIG. 9, a rectangular copper wire 9 whose width is gradually or stepwise changed may be wound around the magnetic core 2. At this time, magnetic core 2
If the rectangular copper wire 9 having the narrowest width of the copper wire which is closest to the magnetic core 2 and the width becomes thicker as the distance from the magnetic core 2 is increased, the magnetic element according to the present embodiment can be obtained.

When winding, the rectangular copper wire 9 and the magnetic core 2
Insulators may be arranged between the two in order to insulate them from each other. As the insulator, for example, a bobbin or the like that covers the periphery of the magnetic body to be the magnetic core 2 can be used.
As the material of the insulator, those generally used as insulators such as resin can be used.

Further, in the present embodiment, since the loss of the magnetic element is greatly reduced, the magnetic material to be the magnetic core is made of a material having a low magnetic permeability such as a metal powder material and a magnetic permeability of ferrite. Various magnetic materials can be used, up to expensive materials. Further, the magnetic core may have a gap.

(Fourth Embodiment) A fourth embodiment of the present invention will be described below with reference to the drawings.

FIG. 10 is a sectional view showing an example of the transformer according to the present embodiment. As shown in FIG. 10, the transformer is one type of magnetic element including a structure in which a plurality of coils 4 are magnetically coupled.

When such a transformer is used in an electronic device such as a switching power supply, a rectifying element, a switching element, etc. are connected to the coil 4, and a large amount of DC-superposed current components flow.

At this time, if at least one coil similar to those of the first and second embodiments is included, the first embodiment will be described.
As in the case of 3 to 3, a low loss magnetic element can be realized.

(Fifth Embodiment) The fifth embodiment of the present invention will be described below with reference to the drawings.

FIG. 11 is a sectional view showing an example of a magnetic element according to this embodiment. A major feature of the magnetic element shown in FIG. 11 is that a solenoid type coil is used as the coil 4.

Even when the solenoid type coil is used as described above, since the leakage magnetic flux from the magnetic core 2 is mainly composed of a component parallel to the coil central axis, the strength of the interlinkage magnetic flux is from the coil central axis. It can be said that it depends on the radial distance. Therefore, by making the coil 4 a solenoid type coil having the same form as in the first to fourth embodiments, it is possible to effectively reduce the loss due to the eddy current and the loss due to the DC resistance at the same time. As a result, a small, thin, and low-loss magnetic element can be realized.

(Sixth Embodiment) The sixth embodiment of the present invention will be described below with reference to the drawings.

FIG. 12 is a cross-sectional view showing an example of a power supply constructed using the magnetic element of the present invention.

As shown in FIG. 12, when the magnetic element 10 according to the present invention is used as a smoothing choke for DC output, or as a transformer, the loss due to eddy current and the loss due to DC resistance are simultaneously and effectively reduced. be able to. As a result, a small, thin, and low-loss power source can be realized.

Further, this magnetic element is replaced by a capacitor 1
2. The power supply itself can be further miniaturized by integrally arranging the power supply control IC 11, the switching element, the rectifying element, etc. in a three-dimensional manner. Such a power supply can be placed near a load that has many restrictions such as height, size, bottom area, heat generation, etc., resulting in improved noise resistance and loss reduction due to shortened pattern wiring. Also, a synergistic effect such as a shield effect using the capacitor electrodes can be expected.

[0084]

As described above, according to the present invention,
It is possible to provide a low-loss magnetic element that can simultaneously achieve reduction of loss due to eddy current and reduction of loss due to DC resistance. Further, by using the magnetic element, a low-loss power source can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a magnetic element according to the present invention.

FIG. 2 is a sectional view showing an example of a magnetic element according to the present invention.

FIG. 3 is a sectional view showing an example of a magnetic element according to the present invention.

FIG. 4 is a schematic diagram showing an example of a coil used in the magnetic element of the present invention.

FIG. 5 is a schematic diagram showing an example of a coil used in the magnetic element of the present invention.

FIG. 6 is a schematic view showing an example of a coil used in the magnetic element of the present invention.

FIG. 7 is a sectional view showing an example of a magnetic element according to the present invention.

FIG. 8 is a schematic diagram showing an example of a magnetic element according to the present invention.

FIG. 9 is a schematic diagram showing an example of a method of manufacturing a magnetic element according to the present invention.

FIG. 10 is a sectional view showing an example of a magnetic element according to the present invention.

FIG. 11 is a sectional view showing an example of a magnetic element according to the present invention.

FIG. 12 is a sectional view showing an example of a power supply according to the present invention.

FIG. 13 is a sectional view showing an example of a conventional magnetic element.

FIG. 14 is a sectional view showing an example of a conventional magnetic element.

FIG. 15 is a sectional view showing an example of a conventional magnetic element.

[Explanation of symbols]

1,21 magnetic material 2.22 magnetic core 3,23 Outer legs 4, 24 coils Air gap between the five split conductors 6 Air gap between conductors 7 conductors 8 split conductors 9 Flat copper wire 10 Magnetic element 11 Power control IC 12 capacitors

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Osamu Inoue             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Yasufumi Nakajima             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5E043 AA08 BA01                 5E070 AA11 AB01 CA02 CA13 CA16

Claims (22)

[Claims] 1. A magnetic element including a coil, wherein the outermost conductor width of the coil is wider than the innermost conductor width. 2. The magnetic element according to claim 1, wherein the conductor width of the outermost circumference is the largest among the conductors of the coil. 3. The width of the conductor wire of the coil gradually increases from the innermost circumference to the outermost circumference.
Alternatively, the magnetic element described in 2. 4. The magnetic element according to claim 1, wherein the width of the wire of the coil is gradually increased from the innermost circumference to the outermost circumference. 5. The coil conductor includes a plurality of split conductors connected in parallel with each other.
The magnetic element according to any one of 1. 6. A magnetic element including a coil, wherein the conductive wire of the coil includes a plurality of divided conductive wires connected in parallel with each other. 7. The magnetic element according to claim 5, wherein the outermost conductor of the coil includes a plurality of divided conductors connected in parallel with each other. 8. The magnetic element according to claim 5, wherein the innermost conductor of the coil includes a plurality of divided conductors connected in parallel with each other. 9. The magnetic element according to claim 5, wherein the number of divided conductors connected in parallel is larger as the conductors on the outer circumference of the coil are larger. 10. The magnetic element according to claim 5, wherein widths of the divided conducting wires connected in parallel are equal to each other. 11. The width of the gap between the split conductors of the coil is:
6. The width is less than or equal to the width of the gap between the conductors.
10. The magnetic element according to any one of items 10 to 10. 12. The magnetic element according to claim 1, wherein the coil has a flat plate shape. 13. The magnetic element according to claim 1, wherein the coil is configured by using at least one layer of a coil pattern formed on a printed circuit board. 14. The magnetic element according to claim 13, wherein the coil pattern is a coil pattern obtained by using a spiral slit. 15. The magnetic element according to claim 1, wherein the coil is formed by using a rectangular copper wire. 16. The magnetic element according to claim 15, wherein the coil includes a structure obtained by winding a rectangular copper wire around a magnetic body serving as a magnetic core. 17. The magnetic element according to claim 1, wherein the coil is formed by using a solenoid coil. 18. A method according to claim 1, further comprising a plurality of coils, the coils being magnetically coupled to each other.
17. The magnetic element according to any one of 17. 19. The magnetic element according to claim 1, comprising a structure in which a first magnetic body is laminated in a plane direction of the coil. 20. The magnetic element according to claim 19, wherein the first magnetic body has a flat plate shape. 21. The magnetic element according to claim 1, wherein a second magnetic body is arranged on at least one of the center and the outer circumference of the coil. 22. A power supply comprising the magnetic element according to any one of claims 1 to 21.