JP2006286667A - Inductance component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an inductance component having a permanent magnet for preventing magnetic flux saturation in which the characteristics can be sustained with no risk of demagnetization. <P>SOLUTION: A plurality of ferrite cores 1 and 2 are combined by forming magnetic gaps 3 and 4 between the cores 1 and 2. At least one core 1, 2 is applied with a coil 5, 6 and combined with permanent magnets 7 and 8. The permanent magnets 7 and 8 constitute a closed magnetic circuit, respectively, for the corresponding core 1, 2. The permanent magnets 7, 8 supply the corresponding core 1, 2, respectively, with magnetic flux Φ2, Φ3 reversely to magnetic flux Φ1 being induced by a DC current flowing through the coil 5, 6 applied to the core 1, 2 being combined. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inductance component that is used as an inductor or a transformer in a switching power supply or the like, and in which a direct current in which an alternating current is superimposed is applied to a coil wound around a core.

  In a choke coil and a transformer such as a switching power supply, an AC current is superimposed on a DC current in each coil in terms of function. Therefore, the cores constituting these choke coils and transformers are required to have high magnetic saturation characteristics.

  In recent years, electronic components such as switching power supplies have been required to be miniaturized, and accordingly, higher frequencies that can reduce the size of components have been achieved. When the frequency is increased, the conventional metal core has a large core loss, making it difficult to use, and it is preferable to use a ferrite core having a small core loss and a high specific resistance. However, the ferrite core has a low saturation magnetic flux density. For this reason, for example, in Patent Document 1, in the gap forming portion of the middle leg of the E-type core. It has been proposed to provide a permanent magnet that supplies a magnetic flux in a direction opposite to the magnetic flux generated by the direct current flowing through the coil.

JP 2002-231540 A

  However, as disclosed in Patent Document 1, if a permanent magnet is provided in the path of the magnetic flux generated by the coil, the permanent magnet is gradually demagnetized due to long-term use. In the case of a transformer, there is a problem that the transformation function is lowered.

  In view of the above problems, an object of the present invention is to provide an inductance component having a permanent magnet for preventing magnetic flux saturation so that the permanent magnet is not demagnetized and can maintain its characteristics. To do.

The inductance component of the present invention is an inductance component having a core for winding a coil for passing a DC current on which an AC current is superimposed,
Combine multiple ferrite cores by forming a magnetic gap between the cores,
Winding a coil around at least one core,
Combined with a core around which the coil is wound, a permanent magnet that supplies a magnetic flux in a direction opposite to the magnetic flux generated by the direct current flowing through the coil wound around the core so as to form a closed magnetic circuit with the core. It is characterized by that.

Further, the inductance component of the present invention is an inductance component having a core for winding a coil for passing a direct current on which an alternating current is superimposed,
Combine two ferrite cores by forming a magnetic gap between the cores,
Winding a coil for passing a direct current to generate magnetic flux in the same direction in the two cores,
Permanent magnets that supply magnetic flux in the direction opposite to the magnetic flux generated by the direct current flowing in the coils wound around the respective cores to the two cores are closed between the permanent magnets and the corresponding cores. It is characterized by combining to form.

Moreover, the inductance component of the present invention is characterized in that the core is a U-shaped core, and the permanent magnet is provided between the inner peripheral surfaces of two opposing magnetic legs of the U-shaped core.

The inductance component of the present invention is
The permanent magnet is a ferrite magnet.

  According to the present invention, a permanent magnet that generates a magnetic flux in a direction opposite to a magnetic flux generated by a direct current flowing in a coil wound around a core with respect to a core between magnetic gaps is configured so that the permanent magnet constitutes a closed magnetic circuit. Since they are combined, the magnetic flux generated by the direct current flowing through the coil is canceled by the amount of magnetic flux supplied from the permanent magnet, and magnetic saturation is suppressed. In the inductance component of the present invention, the permanent magnet is not provided in the magnetic path of the core but in the bypass of the core, and the permanent magnet is magnetized in the opposite direction to the direction of the magnetic flux flowing through the coil. Magnetic flux generated by a direct current flowing through the coil does not flow through the permanent magnet, and substantially no demagnetization of the permanent magnet occurs.

  In addition, since the present invention forms a closed magnetic circuit between the permanent magnet and the core combining the permanent magnet, the effect of canceling the magnetic flux of the permanent magnet with respect to the magnetic flux generated by the direct current flowing through the coil is large, and the design is easy.

  In addition, the inductance component of the present invention has two cores, a permanent magnet is provided for each of the cores, and a direct current flowing in each coil generates a magnetic flux in the same direction with respect to the cores. The permanent magnet is configured to generate a magnetic flux in the opposite direction to the magnetic flux generated by the direct current flowing through each coil. The magnetic flux generated in one coil is combined with the core around which the other coil is wound. Since the permanent magnet generates a magnetic flux in the magnetization direction, it acts on the permanent magnet in the magnetization direction, and a further demagnetization suppressing effect is obtained.

  In addition, the inductance component of the present invention can be realized without increasing the size of the inductance component because the permanent magnet is provided between the inner peripheral surfaces of the magnetic legs of the U-shaped core.

  In the present invention, since not only the core but also the permanent magnet is made of ferrite, the core loss is small, the generation of eddy current is small, and an inductance component suitable for high frequency can be realized.

  FIG. 1 is a diagram showing an embodiment of an inductance component of the present invention. This inductance component constitutes a choke coil for a switching power supply. Reference numerals 1 and 2 denote U-shaped cores which are combined through magnetic gaps 3 and 4. These cores 1 and 2 are made of Mn—Zn or Ni—Zn ferrite. The magnetic gaps 3 and 4 are gaps formed by bonding a non-magnetic material such as a resin sheet or adjusting the interval between the cores with a metal fitting (not shown).

  Reference numerals 5 and 6 denote coils wound around the cores 1 and 2, respectively. Each of the coils 5 and 6 receives a direct current in which an alternating current is superimposed. A magnetic flux Φ1 generated by a direct current flowing through these coils 5 and 6 passes around the cores 1 and 2 in the same direction.

  7 and 8 are permanent magnets combined with the cores 1 and 2, respectively. These permanent magnets 7 and 8 constitute closed magnetic paths with respect to the cores 1 and 2, respectively. Magnetic fluxes Φ2 and Φ3 generated by the permanent magnets 7 and 8 are caused by direct currents flowing through the coils 5 and 6, respectively. The magnetic flux Φ1 is supplied in a direction opposite to the generated magnetic flux Φ1 and canceling out the magnetic flux Φ1 in each of the cores 1 and 2.

  As described above, the permanent magnets 7 and 8 that generate the magnetic fluxes Φ2 and Φ3 in the opposite direction to the magnetic flux Φ1 generated by the direct current flowing in the coils 5 and 6 wound around the cores 1 and 2, respectively, By combining the cores 1 and 2 so as to form a closed magnetic circuit, the magnetic flux generated by the direct current flowing through the coils 5 and 6 is erased by the amount of magnetic flux supplied from the permanent magnets 7 and 8, and magnetic saturation is reduced. Inductance components that can be prevented and can handle a large current can be provided. Further, in order to form a closed magnetic path between the permanent magnets 7 and 8 and the cores 1 and 2 that combine them, the magnetic fluxes Φ 2 and 3 of the permanent magnets 7 and 8 with respect to the magnetic flux Φ 1 generated by the direct current flowing through the coils 5 and 6. The effect of canceling is large, and the design becomes easy.

  Each permanent magnet 7 (8) forms a closed magnetic path with respect to the corresponding core 1 (2), and a magnetic gap with respect to the opposite core 2 (1) of these cores 1 (2). 3 and 4, the magnetic flux Φ 4 (Φ 5) in the direction applied to the counterpart core 2 (1) of the permanent magnet 7 (8) is suppressed by the magnetic gaps 3 and 4. Therefore, the magnetic flux supplied from the permanent magnets 7 and 8 mainly acts in a direction to cancel the magnetic flux Φ1. The magnetic gaps 3 and 4 are preferably set to 0.5 mm or more.

  In the present invention, the permanent magnets 7 and 8 are not provided in the magnetic paths of the cores 1 and 2 but are provided in the bypasses of the cores 1 and 2, and the permanent magnets 7 and 8 are magnetic fluxes flowing in the coils 5 and 6. Since it is magnetized in the direction opposite to the direction of Φ1, the magnetic flux Φ1 generated by the direct current flowing through the coils 5 and 6 does not flow through the permanent magnets 7 and 8, but substantially demagnetizes the permanent magnets 7 and 8. Does not occur.

  Further, permanent magnets 7 and 8 are provided for the two cores 1 and 2, respectively, and direct currents flowing through the coils 5 and 6 generate magnetic fluxes in the same direction with respect to the cores 1 and 2, respectively. 8 is configured to generate magnetic fluxes Φ2 and Φ3 in opposite directions to the magnetic flux Φ1 generated by the direct current flowing in the coils 5 and 6, but the magnetic flux Φ1 generated in one coil 5 (6). Generates a magnetic flux in the magnetization direction for the permanent magnet 8 (7) combined with the core 2 (1) around which the other coil 6 (5) is wound. Therefore, the permanent magnet 8 (7 ) Acts in the magnetization direction, and a further demagnetization suppressing effect is obtained.

  Further, when the present invention is carried out, the permanent magnets 7 and 8 may be provided so as to form a closed magnetic path between the magnetic legs 1a, 1a and 2a, 2a of the U-shaped cores 1 and 2, and the magnetic legs are not necessarily provided. Although it is not necessary to provide between inner peripheral surfaces, like this embodiment, by providing permanent magnets 7 and 8 between inner peripheral surfaces of magnetic legs 1a, 1a and 2a, 2a of magnetic legs 1, 2, This can be realized without increasing the size of the inductance component.

  Moreover, since not only the cores 1 and 2 but also the permanent magnets 7 and 8 are composed of ferrite magnets, an inductance component with a small core loss can be realized even when used for a switching power supply that switches at a high frequency of several tens to 100 kHz, for example. .

  Next, the results of experiments on the arrangement of the permanent magnets 7 and 8 in the inductance component of the present invention will be described. FIG. 2 shows an example of a configuration in which the coil 5 is wound only around one core 1 and only one permanent magnet is arranged with its position and direction changed. 2 (circle 1) is an example in which the permanent magnets 7 and 8 are not provided (comparative example). 2 (circle 2) and (circle 3) are examples in which the permanent magnet 7 is provided only on the core 1 side, and the example of (circle 2) is permanent with respect to the magnetic flux Φ1 generated by the direct current flowing through the coils 5 and 6. This is an example (comparative example) arranged so that the magnetic flux Φ2 supplied by the magnet 7 is in the same direction (added), and (circle 3) is an example (example) arranged in the opposite direction (cancel). is there. 2 (circle 4) and (circle 5) are examples in which the permanent magnet 8 is provided only on the core 2 side where the coil 6 is not wound. The example of (circle 4) is based on the direct current flowing in the coils 5 and 6. The example (comparative example) arrange | positioned so that magnetic flux (phi) 3 supplied with the permanent magnet 8 may be added with respect to the magnetic flux (phi) 1 produced, (circle 5) is the example (comparative example) arrange | positioned so that it may cancel.

The cores 1 and 2 have a width a in the longitudinal direction of the magnetic legs 1a and 2a of 73 mm, a width b in the opposing direction of the magnetic legs 1a and 1a, 2a and 2a, 90.5 mm, a width c of 14 mm, The one having a cross-sectional area of 196 mm ² was used. Further, as the permanent magnets 7 and 8, those having a residual self-sustained density Br of 220 mT, a cross-sectional area of 104 mm ² and a length equal to the interval between the magnetic legs 1a and 1a and 2a and 2a were 46 mm. The magnetic gaps 3 and 4 were zero, and the number of turns of the coil 5 was 33 turns. Inductance was measured by superimposing an alternating current of 0.5 mA on the coil 5 at a frequency of 1 kHz on various direct currents.

  Tables 1 and 3 show changes in the inductance value with respect to changes in the direct current flowing through the coils of the examples (circle 1) to (circle 5) shown in FIG. As can be seen from the comparison of Table 1 and (Circle 1), (Circle 2), and (Circle 3) in FIG. 3, the permanent magnet 7 and the generated magnetic flux Φ2 are coiled from the case without the permanent magnet 7 (Circle 1). In the case where the magnetic flux Φ1 generated by the direct current flowing in the direction 5 is canceled (circle 3), magnetic saturation accompanying an increase in the direct current is suppressed, and a high inductance value L is obtained. Also, when the current value is considered to cause magnetic saturation, the inductance values of both become close.

  In addition, when the permanent magnet 7 is supplied in a direction in which the generated magnetic flux Φ2 is applied to the magnetic flux Φ1 generated by the direct current flowing through the coil 5 (circle 2), compared with the case without the permanent magnet 7 (circle 1), As the direct current increases, magnetic saturation is promoted and the resulting inductance L decreases. Further, when the current value is considered to cause magnetic saturation, the inductance values of the two become substantially the same.

  In the case of (circle 4) and (circle 5) in FIG. 2, since the magnetic gaps 3 and 4 are zero, when the coil 5 is wound only on the core 1 side, the magnetic flux Φ5 toward the core 1 side of the permanent magnet 8 Is larger than the influence of the magnetic flux Φ3 toward the core 2, and the direction of the magnetic flux Φ5 is a direction that cancels out the magnetic flux Φ1 generated by the direct current flowing in the coil 5 (circle 4). The inductance value is higher than in the example of 5).

  FIG. 4 shows an example in which coils 5 and 6 are wound around cores 1 and 2, respectively. 4 (circle 1) is an example in which the permanent magnets 7 and 8 are not provided (comparative example). 4 (circle 2) and (circle 3) are examples in which a permanent magnet 7 is provided on the core 1 side, and (circle 2) of which the generated magnetic flux Φ2 is on the core 1 side and the coils 5, 6 (Circle 3) is an example in which the magnetic flux Φ1 generated by the DC current flowing in the coils 5 and 6 is canceled on the core 1 side. (Example). Further, (circle 4) and (circle 5) in FIG. 4 are examples in which the permanent magnets 7 and 8 are provided on the cores 1 and 2, respectively, and (circle 4) represents the cores 1 and 2, respectively. On the side, magnetic fluxes Φ2 and Φ3 respectively generated by the permanent magnets 7 and 8 are added to the magnetic flux Φ1 generated by the direct current flowing in the coils 5 and 6 (comparative example), and (circle 5) is an example of canceling out ( Example).

  The sizes and materials of the cores 1 and 2 and the permanent magnets 7 and 8 are the same as in the example of FIG. 2, the number of turns of the coils 5 and 6 is 33 and 31, respectively, and these coils 5 and 6 are connected in series with each other. . Moreover, the direct current which flows into the coils 5 and 6 was changed about the case where the dimension of the magnetic gaps 3 and 4 was set to zero, 0.5 mm, and 2.0 mm. The frequency and current value of the alternating current were the same as in FIG.

  Table 2 and FIG. 5 are diagrams showing changes in the inductance value L with respect to changes in DC current when the magnetic gaps 3 and 4 are set to 0.5 mm in the examples of (circle 1) to (circle 5) in FIG. Table 3 and FIG. 6 are diagrams showing changes in the inductance value L with respect to changes in DC current when the magnetic gaps 3 and 4 are set to 2.0 mm in the examples of (circle 1) to (circle 5) in FIG.

  As can be seen from Tables 2 and 3 and FIGS. 5 and 6, the permanent magnets 7 and 8 are provided on the cores 1 and 2 regardless of the size of the magnetic gaps 3 and 4, and the magnetic flux Φ2 of these permanent magnets 7 and 8 is provided. , Φ3 direction is set to cancel the magnetic flux Φ1 generated by the direct current flowing in the coils 5 and 6, respectively, so that magnetic saturation due to the increase of the direct current is suppressed, and the inductance value decreases with the increase of the direct current. On the contrary, when the permanent magnets 7 and 8 are set in a direction to be applied to the magnetic flux Φ1 generated by the direct current flowing through the coils 5 and 6, respectively, the decrease in the inductance value accompanying the increase in the direct current becomes the largest. .

  Regardless of the size of the magnetic gaps 3 and 4, the permanent magnet 7 is provided on one core 1, and the direction of the magnetic flux Φ2 of the permanent magnet 7 is set to cancel the magnetic flux Φ1 generated by the direct current flowing through the coil 5. As a result, the decrease in the inductance value due to the increase in the direct current is less than in the case where the permanent magnets 7 and 8 are not provided. On the contrary, the permanent magnet 7 is applied in the direction of the magnetic flux Φ1 generated by the direct current flowing through the coil 5. By setting, the decrease in the inductance value accompanying the increase in the direct current is greater than when the permanent magnets 7 and 8 are not provided. Therefore, by combining the permanent magnets 7 and 8 with the cores 1 and 2, respectively, and setting the direction of the permanent magnets 7 and 8 so as to cancel the magnetic flux Φ1 generated in the coils 5 and 6, the magnetic saturation of the cores 1 and 2 is achieved. It can be seen that a product with a small change in inductance value can be obtained even with a large direct current.

  Further, as can be seen from the comparison of Tables 2 to 4 and FIGS. 5 to 7, the inductance value when the DC current is small decreases as the magnetic gaps 3 and 4 increase. The change of becomes smaller.

  FIG. 7 shows a change in inductance value with a change in DC current when the number of permanent magnets 7 and 8 is one and two in order to investigate the relationship between the change in magnetic field strength and magnetic saturation. (Circle 1) of FIG. 7 is an example (comparative example) in which the coils 5 and 6 are wound around the cores 1 and 2, respectively, and the permanent magnets 7 and 8 are not provided. (Circle 2) and (Circle 3) in FIG. 7 are examples in which permanent magnets 7 and 8 are provided on the cores 1 and 2, respectively, and (Circle 2) is on the cores 1 and 2, respectively. The magnetic fluxes Φ2 and Φ3 generated by the permanent magnets 7 and 8, respectively, are added to the magnetic flux Φ1 generated by the direct current flowing in the coil 5 (comparative example), and (circle 3) is an example of canceling out (example). is there. 7 (circle 4) (comparative example) and (circle 5) (example) are examples in which two permanent magnets 7 and 8 of (circle 2) and (circle 3) are provided, respectively.

  In addition, the size of the cores 1 and 2 and the permanent magnets 7 and 8, the material, the number of turns of the coils 5 and 6, and the connection were the same as those in FIG. Further, when the dimensions of the magnetic gaps 3 and 4 are zero and 0.5 mm, the direct current flowing through the coils 5 and 6 is changed, and the frequency and current value of the alternating current are the same as those in FIG.

  Table 5 and FIG. 8 are diagrams showing changes in the inductance value L with respect to changes in DC current when the magnetic gaps 3 and 4 are set to 0.5 mm in the examples of (circle 1) to (circle 5) in FIG.

  As can be seen from Table 5 and FIG. 8, when the number of the permanent magnets 7 and 8 is increased to two in the cores 1 and 2, the magnetic saturation promotion effect and the magnetic saturation prevention effect are increased, respectively, and the direct current and the inductance value Affects the correlation. That is, it can be seen that a magnet with a strong magnetic field strength may be used to cope with a large direct current. 7 (circle 1), (circle 2), and (circle 3) have the same configurations as (circle 4) and (circle 5) in FIG. 4, respectively, but the measured values are different. It seems to be based on setting errors and measurement errors of the magnetic gaps 3 and 4.

  The present invention is not only a combination of two U-type cores, but also a combination of a plurality of cores forming two or more magnetic gaps, such as a combination of a U-type core and an I-type core, or two U-type cores and an I-type core. It can be applied to inductors and transformers.

It is a figure which shows one Embodiment of the inductance component by this invention. It is a figure which shows the structure which wound the coil around one core of the U-U core and set various positions and polarities of the permanent magnet. In each example shown in FIG. 2, it is a figure which shows the change of the inductance value with respect to the change of the direct current sent through a coil in the case of a magnetic gap zero. It is a figure which shows the structure which wound the coil with respect to both the cores of UU core, and set the number of permanent magnets, the position, and the polarity variously. In each example shown in FIG. 4, it is a figure which shows the change of the inductance value with respect to the change of the direct current sent through a coil in case a magnetic gap is 0.5 mm. In each example shown in FIG. 4, it is a figure which shows the change of the inductance value with respect to the change of the direct current sent through a coil in case a magnetic gap is 2.0 mm. It is a figure which shows the structure which wound the coil with respect to both the cores of UU core, and set the number and polarity of the permanent magnet variously. In each example shown in FIG. 7, it is a figure which shows the change of the inductance value with respect to the change of the direct current sent through a coil in case a magnetic gap is 0.5 mm.

Explanation of symbols

1, 2: Core, 1a, 2a: Magnetic leg, 3, 4: Magnetic gap, 5, 6: Coil, 7, 8: Permanent magnet

Claims (4)

An inductance component having a core for winding a coil for passing a direct current on which an alternating current is superimposed,
Combine multiple ferrite cores by forming a magnetic gap between the cores,
Winding a coil around at least one core,
Combined with a core around which the coil is wound, a permanent magnet that supplies a magnetic flux in a direction opposite to the magnetic flux generated by the direct current flowing through the coil wound around the core so as to form a closed magnetic circuit with the core. Inductance component characterized by that. An inductance component having a core for winding a coil for passing a direct current on which an alternating current is superimposed,
Combine two ferrite cores by forming a magnetic gap between the cores,
Winding a coil for passing a direct current to generate magnetic flux in the same direction in the two cores,
Permanent magnets that supply magnetic flux in the direction opposite to the magnetic flux generated by the direct current flowing in the coils wound around the respective cores to the two cores are closed between the permanent magnets and the corresponding cores. An inductance component characterized by being combined to form The inductance component according to claim 1 or 2,
The inductance component, wherein the core is a U-shaped core, and the permanent magnet is provided between inner peripheral surfaces of two opposing magnetic legs of the U-shaped core. The inductance component according to any one of claims 1 to 3,
An inductance component, wherein the permanent magnet is a ferrite magnet.

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