JPH03219609A - Laminated-type common-mode choke coil - Google Patents

Abstract

PURPOSE:To reduce the difference in an inductance value between two opposite coils and to prevent the magnetic saturation of a choke coil by a method wherein the area surrounded by a coil whose number of turns is large out of the coils is made smaller than the area surrounded by a coil whose number of turns is small. CONSTITUTION:A laminated-type common-mode chike coil is provided, at the inside, with two coils A, B whose number of turns is different. The pattern of conductor lines for the coils A, B is changed, and areas SA, SB surrounded by the coils A, B are made different. Thereby, the difference DELTAL in an inductance value is made extremely small. That is to say, the area SB surrounded by the coil B whose number of turns is large is made small, or the area SA surrounded by the coil A whose number of turns is small is made large. The ratio SS/SA of the areas surrounded by both coils A, B is selected properly, and the difference DELTAL in the inductance value is made extremely small. Thereby, the difference in the inductance value between the coils whose number of turns is different is made extremely small. When a normal-mode signal is input, magnetic fluxes generated between the coils are balanced and offset and it is possible to prevent the magnetic saturation of the choke coil.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a laminated common mode choke coil in which two coils facing each other are formed inside a laminated block made by laminating and integrating magnetic sheets. Regarding.

[Background Art] [Structure of Laminated Common Mode Choke Coil] FIG. 6 shows a general structure of a two-element (coil) laminated common mode choke coil.

As shown in Fig. 6, the laminated choke coil is made of Ni-
A printed conductor sheet 5 has a coiled conductor line 3a and an extraction electrode 4a printed on the surface of a magnetic sheet 1 made of Zn-based ferrite, etc., and a conductor line 6a, an extraction electrode 7a, and a through hole 8a are provided on the magnetic sheet 1. a printed conductor sheet 9, a coiled conductor line 3b on the magnetic sheet 1,
A printed conductor sheet 1o provided with an extraction electrode 4b and a through hole 8b, and a conductor line 6 on the surface of the magnetic sheet 1.
a conductor printed sheet 11 provided with a lead electrode 7b, a through-hole dummy sheet 13 in which through-holes 12 are formed in the magnetic sheet 1, and a dummy sheet 14 without any processing (just a magnetic sheet 1). A laminate block 2 is constructed by laminating and integrating a plurality of these magnetic sheets 1 as shown in FIG. Moreover, inside this laminated body block 2, conductor lines 3a, 6a, 3b, 8
Two coils A and B are formed by b and d.

One coil A has a plurality of through-ball dummy sheets 13 in between, and conductor printed sheets θ are placed above and below.

5 are laminated, and upper and lower conductor lines 6a, 3a are electrically connected via through holes 12. The input side extraction electrode 7a of the coil A constituted by the conductor lines 3a and 6a is provided at the end of the conductor line 6a at the edge of one conductor print sheet 8, and the output side extraction electrode 4a is It is provided at the end of the conductor line 3a at the edge of the other conductor print sheet 5. Similarly, the other coil B has a plurality of through-hole dummy sheets 13
The conductor printed sheets 10 and 11 are stacked on top and bottom with the conductor printed sheets sb and eb interposed therebetween, and the upper and lower conductor lines sb and eb are electrically connected via through holes 13. In addition, the conductor line 3b
, 6b on the input side of the coil B is provided at the end of the conductor line 8b at the edge of one conductor printed sheet 11, and the output side extraction electrode 4
b is provided at the end of the conductor line 3b at the edge of the other conductor print sheet 10. Note that the through-hole dummy sheet 13 is designed to reduce stray capacitance between the conductor lines 6a and 3a,
It is used to reduce stray capacitance between conductor lines 6b and 8b.

Sheets 9, 13, 6 on which coil A is formed and sheets 10, 13, 11 on which coil B is formed are stacked vertically with a plurality of dummy sheets 14 in between.
, B are arranged to face each other, and the common mode choke coil is an equinodal circuit as shown in FIG. Note that the dummy sheet 14 is used to adjust the stray capacitance between the coil A and the coil B.

Furthermore, a plurality of dummy sheets 14 are laminated on the top and bottom layers for the purpose of insulating and protecting the coils A and B.

In addition, the above-mentioned laminated common mode choke coil is made of Ag
Alternatively, magnetic sheets in the form of green sheets with conductor lines and through holes formed using conductive paste such as Ag-Pd are laminated in a predetermined order, pressed together, and fired to form a laminate block. However, it is manufactured by providing external electrodes of both coils on the surface of the laminate block so as to be electrically connected to each extraction electrode.

(Conventional Laminated Common Mode Choke Coil) FIG. 8 shows a comparison of the pattern structures of coil A and coil B in a conventional laminated common mode choke coil. That is, the coils A and B are configured to face each other, and are formed in a pattern that is symmetrical with respect to the dummy sheet 14 except for both ends. Therefore, the area SA surrounded by coil A (illustrated as a rope; the same applies to others) and the area SBO surrounded by coil B are:
Equal to each other, S A = S a. It becomes.

[Problems to be Solved by the Invention] The pattern shown in FIG. 8 is a coil pattern of a nominally 1.5 turn type common mode choke coil.

However, both coils A and B have a lead-out voltage 8j4a,
Since it is necessary to configure so that the positions of 4b, 7a, and 7b do not overlap, the number of turns is not exactly equal. That is, if one side of the magnetic sheet 1 is calculated as 174 turns, in the pattern shown in FIG. 8, the number of turns of coil A is 5/4 turns, and the number of turns of coil B is 7.
/4 turns, and there is a difference of 172 turns between Oka coils A and B. This is the same even if the nominal number of turns is changed to 2.5 turns, 3.5 turns, etc., and a difference of 1/2 turn will always occur. Therefore, the inductance value LA of the coil A and the inductance value La of the coil B are not equal, and always LA<L,B.

Note that this difference in inductance value (hereinafter, the difference ΔL in inductance value will be considered as a value normalized by dividing LA-LB by the average value of inductance r = LA + LB) becomes smaller as the number of turns becomes smaller. ,growing. The actual value is
In the above example, LA=6.7 μH, L=8.7 μH, and ΔL=2θ%.

However, signals are generally input to the common mode choke coil in the normal mode type, but in conventional laminated type common mode choke coils, the difference in inductance value ΔL is large, so a signal is generated between the two coils. There was a problem in that the magnetic fluxes in opposite directions became unbalanced and did not cancel each other out, causing magnetic saturation in the choke coil, resulting in loss of its function as an inductor.

The present invention has been made in view of the drawbacks of the conventional examples of diagonal tops, and its purpose is to reduce the difference in inductance values between two opposing coils in a laminated common mode choke coil. , the purpose is to prevent magnetic saturation of the choke coil.

[Means for Solving the Problems] Therefore, the laminated common mode choke coil of the present invention includes a laminated body block formed by laminating and integrating a plurality of magnetic sheets, and a laminated block formed on the surface of the magnetic sheet. In a common mode choke coil formed in the laminated block, two coils facing each other with different numbers of turns are formed in the multilayer block by a conductor line, and the area surrounded by the coil with a larger number of turns is surrounded by the coil with a smaller number of turns. It is characterized by making the difference in inductance values between the two coils extremely small by making it smaller than the area.

[Operation] The present invention minimizes the difference in inductance value between the two coils (preferably, makes the difference in inductance value zero) by making the surrounding areas of two coils with different numbers of turns different. be.

In other words, the inductance value of a coil increases as the number of turns in the coil increases, and decreases as the area (cross-sectional area) surrounded by the coil decreases. By making it smaller than , the difference in inductance values between both coils can be made small, and by appropriately setting the ratio of the areas surrounded by both coils, it is possible to make the difference in inductance values extremely small.

By minimizing the difference in inductance values between coils with different numbers of turns, when a normal mode signal is input, the magnetic flux generated between the coils balances and cancels each other out, resulting in magnetic saturation of the choke coil. This can be prevented.

Example] Hereinafter, the present invention will be explained with reference to FIGS. 1 to S.

The laminated common mode choke coil according to the present invention has a structure as shown in FIG. 6, and has two coils A and B having different numbers of turns inside. In a laminated common mode choke coil with such a structure,
If the area surrounded by both coils A and B is equal as in the conventional case, the difference ΔL in inductance value becomes large. By making the surrounding areas SA and SB different, the difference ΔL in inductance values is made extremely small. In other words, the area SB surrounded by the coil B with a large number of turns
The difference ΔL in inductance value can be made extremely small by decreasing , or by increasing the area SA surrounded by coil A with a small number of turns, and by appropriately selecting the ratio SB/SA of the area surrounded by both coils A and B. It is something to do. In particular, it is preferable that the difference ΔL in inductance values be zero.

Next, a method for determining the ratio SB/SA of the area surrounded by both coils A and B in order to minimize the difference ΔL in inductance values will be explained. Figures 1 to 4 show each sample 1 in which the pattern of coil A with a small number of turns is kept as is, and the pattern of coil B with a large number of turns is changed to gradually reduce the area SB surrounded by coil B. This shows the pattern structure of both coils of 4 to 4. That is, Figure 1~
If the area SB surrounded by the coil B in each of samples 1 to 4 in FIG.
Bs>S 84. These Figures 1 to 4
Sample 1 with coils A and B of the pattern shown in the figure
-4 common mode choke coils shown in FIG. ．． 6. A conventional common mode choke coil having B is manufactured,
Area S^ surrounded by coils A and B of each common mode choke coil.

The inductance values L^ and LB of SB and each of the coils A and B are measured, and the relationship between the ratio SB/S9 of the area surrounded by the coils A and B and the difference ΔL between the inductance values is determined.

An example of this is shown in Table 1.

Table 1, FIG. 5 shows the relationship between the difference ΔL in the inductance values obtained in this manner and the ratio SB/SA of the area surrounded by the coils A and B, using a curve. From the curve interpolated between these measurement points, by setting the coil pattern so that S , / S A = 0.39, coil A and coil B
It can be seen that it is possible to eliminate the unbalance of the inductances, make the difference ΔL in inductance values zero or extremely small, and prevent magnetic saturation of the choke coil.

In the above explanation, the pattern of coil B with a large number of turns was changed, but it goes without saying that the pattern of coil A with a small number of turns may be changed to find an appropriate value of SB/SA. be.

In addition, the ratio S a / S A of the area surrounded by coils A and B changes depending on various conditions, and is 0.39 above.
This value is an example.

[Effects of the Invention] According to the present invention, in a laminated common mode choke coil including two coils, it is possible to minimize the difference in inductance values between coils having different numbers of turns. Therefore, the maximum usable current value can also be increased.

[Brief explanation of drawings]

FIGS. 1, 2, 3, and 4 are diagrams for explaining the present invention, and are a plan view showing two coils in which the area surrounded by one coil is gradually changed, and FIG. The figure is a graph showing the relationship between the ratio of the area surrounded by two coils and the difference in inductance value between both coils, Figure 6 is an exploded perspective view showing the configuration of a laminated common mode choke coil, and Figure 7 is the equivalent of the same as above. The circuit diagram, FIG. 8, is a plan view showing two coils in a conventional example. 1...Magnetic material sheet 2...Laminated body block 3a, 3b, e3a, 6b-Conductor lines A, B...Coil S person +SBl~SB4...Area surrounded by coil Fig. 5

Claims (1)

[Claims] (1) A laminate block is formed by laminating and integrating a plurality of magnetic sheets, and two coils facing each other with different numbers of turns are placed in the laminate block by a conductor line formed on the surface of the magnetic sheet. In a common mode choke coil formed in A multilayer common mode choke coil characterized by: