JP4375975B2 - Magnetic coupling element - Google Patents

Description

【００３５】
表１から分かるように、本発明によれば、比較例１、２とほぼ同等のインダクタンス値が得られる。また、本発明の実施例によれば、比較例１、２に比較し、大きな結合係数が得られ、端子部における結合が結合係数の増大に寄与していることが分かる。本発明の磁気結合素子は、０．５ＭＨｚ以上の駆動周波数で好適に用いられる。
【００３６】
【発明の効果】
本発明によれば、結合係数の高い磁気結合素子が得られ、伝送効率を上げることができる。また、第１の導電体、第２の導電体が板状をなすので、抵抗値が小さく、大電流に対応が可能である。さらに、漏れインダクタンスが小さいので、スイッチング電源に用いた場合、漏れ磁束のエネルギーが原因となるスイッチング時のサージ電圧が小さくなり、より耐圧の低いスイッチング素子を用いることができる。
【図面の簡単な説明】
【図１】本発明による磁気結合素子を適用するスイッチング電源の一例を示す回路図である。
【図２】図１の回路の動作を説明する波形図である。
【図３】本発明による磁気結合素子の一実施例を示す斜視図である。
【図４】図３のＸ−Ｘ断面図である。
【図５】図３のＹ−Ｙ断面図である。
【図６】本発明による磁気結合素子の他の実施例を磁性体を省略して示す斜視図である。
【図７】本発明による磁気結合素子の他の実施例を磁性体を省略して示す斜視図である。
【図８】本発明による磁気結合素子の他の実施例を示す斜視図である。
【図９】本発明による磁気結合素子の他の実施例を磁性体を省略して示す斜視図である。
【図１０】磁気結合素子の比較例を磁性体を省略して示す斜視図である。
【図１１】磁気結合素子の比較例を磁性体を省略して示す斜視図である。
【符号の説明】
１：磁気結合素子、２：第１の導電体、２ａ〜２ｄ、２ｇ、２ｈ：端子、２ｅ、２ｆ：連絡部、３、３０、３１：第２の導電体、３ａ〜３ｄ、３ｇ〜３ｊ、３ｎ、３ｐ、３ｑ、３ｒ：端子、３ｅ、３ｆ、３ｋ、３ｍ：連絡部、４：絶縁材、５ａ、５ｂ：磁性体、６：窓[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic coupling element such as a transformer or a tap inductor used in a switching power supply with a large current output that operates at a relatively high frequency.
[0002]
[Prior art]
In recent years, the driving frequency of switching power supplies has been increased more and more due to advances in semiconductor switching elements such as FETs and advances in circuit technology such as soft switching. When the drive frequency is increased in this way, the inductance value required for the transformer, choke coil, etc. can be reduced. For this reason, as described in Patent Document 1, for example, an inductor having a structure in which a linear conductor is sandwiched between upper and lower magnetic bodies can be used. Further, as a magnetic coupling element used in a converter described later included in the switching power supply, it is conceivable to adopt a structure in which the linear conductors are overlapped and surrounded by a magnetic material.
[0003]
[Patent Document 1]
JP 2000-323336 A.
[0004]
[Problems to be solved by the invention]
As described above, when the magnetic coupling element is configured by applying the inductor described in Patent Document 1, the effect of the leakage inductance is relatively increased when the inductance value is decreased. For this reason, there is a problem that the coupling coefficient K shown in the following equation (1) becomes small and the transmission efficiency is lowered. In Equation (1), M is a mutual inductance value, and l ₁ and l ₂ are self-inductance values of the respective conductors (coils).
[0005]
K = M / (l ₁ · l ₂ ) ^1/2 (1)
In recent years, switching power supplies for office equipment have been requested to reduce the voltage and increase the current so that the output voltage of the switching power supply is, for example, 1 V or less in order to save energy.
[0006]
In view of the above problems, an object of the present invention is to provide a magnetic coupling element that has a high coupling coefficient and can meet the demand for low voltage and large current.
[0007]
Another object of the present invention is to provide a magnetic coupling element that reduces a surge voltage during switching and can be used even with a switching element having a lower withstand voltage.
[0008]
[Means for Solving the Problems]
(1) A magnetic coupling element according to the present invention is a magnetic coupling element including a first conductor and a second conductor to be electromagnetically coupled to each other.
The first conductor and the second conductor have a rectangular plate shape,
The first conductor and the second conductor are stacked via an insulating material, and a magnetic body is disposed above and below the stacked conductor,
The first conductor and the second conductor each have a terminal on a pair of sides facing each other, and at least one terminal has the same number of terminals on the same side of the first conductor and the second conductor. There are multiple conductors,
The terminals located on the same side of the first conductor and the second conductor are arranged with the terminals of the other conductor positioned between the terminals of one conductor, and the first conductor The plate surface of the conductor and the terminal of the second conductor is aligned with the end face of the magnetic body, and the lower end of the terminal of at least one of the first conductor and the second conductor The plate surface of the portion is in contact with the bottom surface of the magnetic body.
[0009]
(2) In the magnetic coupling element of the present invention, the plate surface of the lower end portion of the conductors of both the first conductor and the second conductor is brought into contact with the bottom surface of the magnetic body. It is characterized by that .
[0010]
( 3 ) Further, in the magnetic coupling element of the present invention, a plurality of terminals on the same side of the first conductor and / or the second conductor are connected by a connecting portion provided at a lower end portion of the terminal. Features.
[0011]
( 4 ) The magnetic coupling element of the present invention is characterized in that a plurality of at least one of the first conductor and the second conductor is provided.
[0012]
( 5 ) The magnetic coupling element of the present invention is characterized in that either one of the first conductor and the second conductor is covered with an insulating material.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an example of a circuit to which the magnetic coupling element of the present invention is applied. This circuit is a circuit constituting a step-down DC-DC converter called a tap inductor type for a switching power supply. This converter obtains an output voltage of about DC1V to about DC1V, for example. In FIG. 1, E is a DC power source, S1 and S2 are switching elements such as MOSFETs, and 1 is a tap inductor. The tap inductor 1 includes a coil L1 and a coil L2 that are electromagnetically coupled to each other. C is a capacitor and R is a load.
[0014]
FIG. 2 is an operation waveform diagram of the circuit of FIG. 1, and the switching elements S1 and S2 are alternately turned on. When the switching element S1 is turned on, a current i1 flows to the capacitor C and the load R through the tap inductor 1. When the switching element S1 is turned off and the switching element S2 is turned on, the current i2 from the coil L2 to the capacitor C and the load R flows due to the energy stored in the tap inductor 1.
[0015]
In the circuit using the tap inductor 1, since the current i1 flows through the coils L1 and L2 when the switching element S1 is turned on, the value of the current i1 is smaller than that of the conventional converter including only the coil L2. Further, by adjusting the turns ratio of the coils L1 and L2, it is possible to obtain a low voltage output with a larger time ratio as compared with the conventional step-down converter.
[0016]
Thus, in this circuit, the tap inductor 1 is one element and has two roles of output filter and voltage conversion. Further, the step-down converter using the tap inductor can obtain a low voltage output with a large duty ratio, and therefore has an advantage that the loss due to the resistance when the switching element S1 is turned on is reduced and the efficiency is improved.
[0017]
In the conventional step-down converter, since the input voltage is directly applied to the switching element S2, it is necessary to use one having a relatively high breakdown voltage. On the other hand, in the circuit of FIG. 1, since a voltage close to the output voltage is applied to the switching element S2, there is an advantage that a low breakdown voltage and low on-resistance MOSFET can be used.
[0018]
In order to increase the transmission efficiency, the converter of FIG. 1 needs to have a large current capacity in order to increase the coupling coefficient K between the coils L1 and L2 and to meet the demand for low voltage and large current.
[0019]
FIG. 3 is a perspective view of an embodiment (Example 1) of a magnetic coupling element according to the present invention realized in response to such a demand, FIGS. 4 and 5 are sectional views taken along line XX of FIG. It is -Y sectional drawing. 3 to 5, reference numeral 2 denotes a first conductor, and 3 denotes a second conductor. These conductors 2 and 3 are all rectangular and are preferably made of a highly conductive metal such as copper or aluminum.
[0020]
These conductors 2 and 3 are superposed via an insulating material 4. As the insulating material 4, an insulating sheet made of resin or the like may be used as shown in the figure, and one of the conductors may be covered with the insulating material. However, at least one of the opposing surfaces of the conductors 2 and 3 may be used in advance. On the other hand, an insulating material may be covered in a layered manner.
[0021]
Reference numerals 5a and 5b denote magnetic bodies provided so as to cover the periphery of a superposition of the first conductor 2 and the second conductor 3. In this example, the lower magnetic body 5a is constituted by a U-shaped core, the upper magnetic body 5b is constituted by an I-shaped core, and these are combined by a method such as bonding them. And the window 6 which accommodates the conductors 2 and 3 is formed between both. Instead of this, a combination of U-shaped and U-shaped cores may be used. Moreover, you may combine by the method of adhere | attaching the both sides of a core by the combination of I-type-I-type core .
[0022]
As the magnetic bodies 5a and 5b, a compacted body of metal magnetic powder, a metal magnetic body whose surface is insulated, ferrite, or the like can be used.
[0023]
A pair of opposing sides of the first conductor 2, that is, portions protruding from both ends of the magnetic bodies 5a and 5b, have two terminals 2a, 2b and 2c, 2d, respectively. In addition, a pair of opposing sides of the second conductor 3, that is, portions protruding from both ends of the magnetic bodies 5a and 5b, have two terminals 3a, 3b and 3c, 3d . These terminals 2a to 2d and 3a to 3d are such that the terminals 2a and 2b (2c and 2d) of the first conductor 2 and the terminals 3a and 3b (3c and 3d) of the second conductor 3 are alternately arranged. Configured to be adjacent. These terminals 2a to 2d and 3a to 3d are in contact with a portion a formed along the plate surface along the end surface of the magnetic body 5a and the lower surface of the magnetic body 5a. A portion b to be attached (see FIG. 4).
[0024]
The terminals 2a and 2b, 2c and 2d on the same side of the first conductor 2 are commonly connected to a land of a printed circuit board (not shown) by soldering or the like. The terminals 3a and 3b, 3c and 3d on the same side of the second conductor 3 are also commonly connected to a land of a printed circuit board (not shown) by soldering or the like. One of the first conductor 2 and the second conductor 3 constitutes the coil L1 of FIG. 1, and the other constitutes the coil L2.
[0025]
As described above, the magnetic coupling element includes the first conductor 2 and the second conductor 3 which are stacked in a plate shape, and the terminals 2a, 2b and 3a, 3b and 2c, 2d and 3c, 3d. Are alternately adjacent to each other at the end faces of the magnetic bodies 5a and 5b, so that a large coupling coefficient can be obtained and a large current can be passed by forming a plate shape. Further, since the coupling coefficient is large, when used as the magnetic coupling element 1 of the converter of FIG. 1, the switching surge voltage caused by the leakage magnetic flux is reduced, and the switching element S1 having a lower withstand voltage can be used. .
[0026]
FIG. 6 is a perspective view showing another embodiment (Example 2) of the magnetic coupling element according to the present invention, in which the magnetic bodies 5a and 5b are omitted. In the present embodiment, the terminals 2a and 2b, 2c and 2d on the same side of the first conductor 2 are connected by connecting portions 2e and 2f which are integrated with these terminals, respectively. The terminals 3a and 3b, 3c and 3d on the same side of the second conductor 3 are also connected by connecting portions 3e and 3f, respectively.
[0027]
According to the embodiment of FIG. 6, since the connecting portions 2e, 2f, 3e, and 3f are provided, it is not necessary to provide a pattern for connecting terminals on the printed circuit board, and it is easy to design a conductive pattern on the printed circuit board side. Become.
[0028]
FIG. 7 is a perspective view showing another embodiment (Example 3) of the magnetic coupling element according to the present invention, in which the magnetic bodies 5a and 5b are omitted. In this embodiment, two terminals 3g, 3h and 3i, 3j are formed at both ends of the second conductor 3, and one terminal 2g, 2h is formed at both ends of the first conductor 2. The terminals 2g and 2h of the first conductor 2 are respectively arranged between the terminals 3g and 3h of the first conductor 3 and between 3i and 3j.
[0029]
FIG. 8 is a perspective view showing another embodiment (Example 4) of the magnetic coupling element according to the present invention. In this embodiment, the terminals 3g and 3h, 3i and 3j in the embodiment of FIG. 7 are connected by connecting portions 3k and 3m, respectively. According to the present embodiment, an effect that the design of the wiring pattern of the printed board described with reference to FIG. 6 can be facilitated is obtained.
[0030]
FIG. 9 is a perspective view showing another embodiment (embodiment 5) of the magnetic coupling element of the present invention, in which the magnetic bodies 5a and 5b are omitted. In the present embodiment, the second conductors 30 and 31 are stacked on the upper and lower sides of the first conductor 2 with the insulating material 4 interposed therebetween, and terminals 3n and 3p are provided at both ends of the conductor 30, Terminals 3q and 3r are provided at both ends. Further, the terminals 2g and 2h of the first conductor 2 are arranged between the terminals 3n and 3q and 3p and 3r of the second conductors 30 and 31 on the same side. According to the embodiment of FIG. 9, a larger current can be handled.
[0031]
FIG. 10 shows a comparative example 1 in which the magnetic bodies 5a and 5b are omitted. In this comparative example 1, the first conductor 2 and the second conductor 3 are overlapped with an insulating material 4 interposed between the first conductor 2 and the second conductor 3 on the same side. Each terminal 2x and 3x, 2y and 3y are provided and adjacent to each other.
[0032]
FIG. 11 shows a comparative example 2, in which the magnetic bodies 5a and 5b are omitted. In the second comparative example, the first conductor 20 and the second conductor 32 are joined side by side via an insulating material 40, and the first conductor 20 and the second conductor 32 are respectively connected to the same side. The terminals 2x and 3x, 2y and 3y are provided one by one and are adjacent to each other.
[0033]
In order to confirm the effect of increasing the coupling coefficient according to the present invention, the coupling coefficient of each of the embodiments and the comparative example and the inductance value of the first conductor 2 are obtained by simulation calculation at 1 MHz (magnetic field analysis by the finite element method). It was. In this calculation, the length (left and right length in FIG. 4) of the core composed of the magnetic bodies 5a and 5b is 11 mm, the width (left and right length in FIG. 5) is 12 mm, and the thickness (FIG. 4, FIG. 5), the vertical width of the window 6 was 1 mm, the thickness of the magnetic body 5a and the thickness of the bottom plate portion of the magnetic body 5b were 2 mm. Further, the magnetic permeability of the magnetic bodies 5a and 5b was set to 30. Further, the first conductor 2 and the second conductor 3 in the comparative example 1 of FIGS. 3 to 8 and 10 have a width of 7.6 mm and a thickness of 0.3 mm, and the first conductor of FIG. The thickness of 2 and the 2nd conductors 30 and 31 was 0.2 mm, and the thickness of the 1st conductors 20 and 32 of the comparative example 2 of FIG. 11 was 0.7 mm.
[0034]
[Table 1]

[0035]
As can be seen from Table 1, according to the present invention, an inductance value substantially equivalent to that of Comparative Examples 1 and 2 can be obtained. Moreover, according to the Example of this invention, compared with the comparative examples 1 and 2, a big coupling coefficient is obtained and it turns out that the coupling | bonding in a terminal part has contributed to the increase in a coupling coefficient. The magnetic coupling element of the present invention is suitably used at a driving frequency of 0.5 MHz or higher.
[0036]
【The invention's effect】
According to the present invention, a magnetic coupling element having a high coupling coefficient can be obtained, and transmission efficiency can be increased. In addition, since the first conductor and the second conductor have a plate shape, the resistance value is small and a large current can be dealt with. Furthermore, since the leakage inductance is small, when used in a switching power supply, the surge voltage at the time of switching caused by the energy of the leakage magnetic flux is reduced, and a switching element with a lower withstand voltage can be used.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an example of a switching power supply to which a magnetic coupling element according to the present invention is applied.
FIG. 2 is a waveform diagram for explaining the operation of the circuit of FIG. 1;
FIG. 3 is a perspective view showing an embodiment of a magnetic coupling element according to the present invention.
4 is a cross-sectional view taken along the line XX of FIG.
5 is a cross-sectional view taken along the line YY in FIG. 3;
FIG. 6 is a perspective view showing another embodiment of the magnetic coupling element according to the present invention, omitting the magnetic body.
FIG. 7 is a perspective view showing another embodiment of the magnetic coupling element according to the present invention, omitting the magnetic body.
FIG. 8 is a perspective view showing another embodiment of the magnetic coupling element according to the present invention.
FIG. 9 is a perspective view showing another embodiment of the magnetic coupling element according to the present invention, omitting the magnetic body.
FIG. 10 is a perspective view showing a comparative example of the magnetic coupling element with a magnetic body omitted.
FIG. 11 is a perspective view showing a comparative example of the magnetic coupling element with a magnetic body omitted.
[Explanation of symbols]
1: magnetic coupling element, 2: first conductor, 2a to 2d, 2g, 2h: terminal, 2e, 2f: connecting part, 3, 30, 31: second conductor, 3a to 3d, 3g to 3j 3n, 3p, 3q, 3r: terminal, 3e, 3f, 3k, 3m: connecting portion, 4: insulating material, 5a, 5b: magnetic material, 6: window

Claims (5)

In a magnetic coupling element comprising a first conductor and a second conductor to be electromagnetically coupled to each other,
The first conductor and the second conductor have a rectangular plate shape,
The first conductor and the second conductor are stacked via an insulating material, and a magnetic body is disposed above and below the stacked conductor,
The first conductor and the second conductor each have a terminal on a pair of opposite sides, and at least one of the terminals on the same side of the first conductor and the second conductor. There are multiple conductors,
The terminals located on the same side of the first conductor and the second conductor are arranged with the terminal of the other conductor positioned between the terminals of one conductor, and the first conductor The plate surface of the conductor and the terminal of the second conductor is aligned with the end surface of the magnetic body, and the lower end of the terminal of at least one of the first conductor and the second conductor A magnetic coupling element, wherein the plate surface of the portion is brought into contact with the bottom surface of the magnetic body. The magnetic coupling element according to claim 1,
A magnetic coupling element , wherein the plate surfaces of the lower ends of the terminals of both the first conductor and the second conductor are brought into contact with the bottom surface of the magnetic body . The magnetic coupling element according to claim 1 or 2 ,
A magnetic coupling element, wherein a plurality of terminals on the same side of the first conductor and / or the second conductor are connected by a connecting portion provided at a lower end portion of the terminal. The magnetic coupling element according to any one of claims 1 to 3 ,
A magnetic coupling element comprising a plurality of at least one of the first conductor and the second conductor. The magnetic coupling element according to claim 4 .
A magnetic coupling element, wherein one of the first conductor and the second conductor is covered with an insulating material.

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