JP4197327B2 - Inductance parts - Google Patents

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 not to be magnetically saturated and to have good magnetic permeability 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, Patent Document 1 proposes that a permanent magnet for supplying a magnetic flux in a direction opposite to the magnetic flux generated by the direct current flowing in the coil is proposed in the gap forming portion of the middle leg of the E-type core.

JP 2002-231540 A

However, as disclosed in Patent Document 1, if a permanent magnet is provided in the path of magnetic flux generated by the coil, the permanent magnet is demagnetized, so that the bias amount of the choke coil and transformer magnet varies from the design value. Therefore, there is a problem that predetermined performance cannot be obtained.
As an inductance component present inventors have that can solve this problem, in Japanese Patent Application No. 2005-100383, a plurality of ferrite cores, combined to form a magnetic gap between the core, a coil wound thereabout at least one core, The core around which the coil is wound is provided with a pair of permanent magnets for supplying a magnetic flux in a direction opposite to the magnetic flux generated by the direct current flowing through the coil wound around the core. We proposed what was provided on the surface of the core so as to pass through the coil winding part.

  The present invention relates to an improvement of the invention of the prior application. In an inductance component having a permanent magnet for preventing magnetic flux saturation, there is no risk of demagnetization of the permanent magnet, characteristics can be maintained, and manufacture is facilitated. It aims at providing the thing of composition.

The inductance component of the present invention is an inductance component having a core for winding at least one coil for passing a DC current superimposed with an AC current,
Form one magnetic gap in the ferrite core,
A pair of permanent magnets that supply a magnetic flux in a direction opposite to a magnetic flux generated by a direct current flowing in a coil wound around the ferrite core, so that the magnetic flux supplied by the permanent magnet passes through the coil winding portion of the core. One magnet is provided on the surface of the core in the vicinity of the magnetic gap so that the surface facing the surface and the opposite surface are opposite in polarity, and the other magnet has the magnetic gap between the one magnet and the other magnet. The surface of the core in the vicinity of the magnetic gap so as to be sandwiched between the magnets is provided with a polarity opposite to that of the one magnet so that the surface facing the surface and the opposite surface are opposite in polarity. .

  Here, the surface of the core means a surface exposed to the outside air that is not embedded in the core, and includes the back surface when the front and back surfaces of the core are assumed, the inner peripheral surface of the U-shaped core, and the like. .

The inductance component of the present invention is characterized in that the permanent magnet is provided on the inner peripheral surface of the ferrite core.

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

According to the present invention, a pair of permanent magnets that generate a magnetic flux in a direction opposite to a magnetic flux generated by a direct current flowing in a coil wound around a core between the magnetic gaps are sandwiched between the magnetic gap and the surface of the core. Since the permanent magnet is provided so that the magnetization direction is perpendicular to the surface, 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 provided not on the magnetic path of the core but on the surface of the core, and substantially no demagnetization of the permanent magnet occurs.

  Further, since the inductance component of the present invention is provided with a permanent magnet on the surface of the core, it can be easily attached by pasting or the like, and can be retrofitted to an existing inductance component.

Further, if a magnetic gap is formed at each abutting portion by combining a plurality of cores, precise manufacturing work for accurately aligning the magnetic gap is required. In the present invention , one core is used. Since it is configured to have a magnetic gap, manufacturing is facilitated.

  Further, in the inductance component of the present invention, by providing a pair of permanent magnets so that a magnetic gap is interposed therebetween, a good magnetic saturation suppression effect by the permanent magnets can be obtained. In addition, since a small permanent magnet can be used, the inductance component can be reduced in size.

  In the inductance component of the present invention, by providing the permanent magnet on the inner peripheral surface of the ferrite core, the permanent magnet does not protrude from the outer peripheral surface of the core, and the inductance component can be reduced in size.

  In the inductance component of the present invention, by providing the permanent magnet in the vicinity of the magnetic gap, a good magnetic saturation suppression effect can be obtained over almost the entire circumference of the core.

  In addition, in the inductance component of the present invention, not only the core but also the permanent magnet is made of ferrite, so that an inductance component suitable for high frequency can be realized with less generation of eddy currents, and hence less core loss.

  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. 1 is a combination of two U-shaped cores 1a and 1b and a core block 1c with one magnetic gap 2 and two adhesive portions 3 that are substantially no gaps. The core 1 is made of Mn—Zn or Ni—Zn ferrite.

  In the present embodiment, the core block 1c made of ferrite is fixed between the leg portions 1f and 1g on one side of the two U-shaped cores 1a and 1b. The magnetic gap 2 is formed by adhering a non-magnetic material such as a resin sheet between the tips of the leg portions 1d and 1e on the other side, or adjusting the interval between the cores with a metal fitting (not shown). . In order to make the adhesion part 3 of the ferrite block 1c substantially no gap, the thickness of the adhesion part 3 is preferably 50 μm or less, more preferably 30 μm or less. The width g of the magnetic gap 2 is 1/200 to 1/10 of the length of the inner circumference of the core 1, and preferably 1/100 to 1/20.

  Reference numerals 4 and 5 denote coils wound around the core 1, and each of the coils 4 and 5 receives a direct current in which an alternating current is superimposed. A magnetic flux Φ1 generated by a direct current flowing through these coils 4 and 5 passes around the core 1 in the same direction.

Reference numerals 6 and 7 denote a pair of permanent magnets provided for suppressing magnetic saturation of one core 1. These permanent magnets 6 and 7 are provided with one magnetic pole (the permanent magnet 6 is an S pole and the permanent magnet 7 is an N pole) facing the surface of the core 1. That is, the magnetizing direction of the pair of permanent magnets 6 and 7 is perpendicular to the core surface (the polarity of the surface with respect to the surface of the core 1 and the opposite surface is opposite), and the permanent magnets 6 and 7 The magnetic gap 2 is provided in the vicinity of the magnetic gap 2 of the core 1 so that 7 has a reverse polarity with respect to the surface. The magnetic flux Φ2 generated by the paired permanent magnets 6 and 7 is opposite to the magnetic flux Φ1 generated by the direct current flowing in the coils 4 and 5, respectively, and is in a direction to cancel the magnetic flux Φ1 in each core 1. Supplied.

  In this way, by providing the permanent magnets 6 and 7 that generate the magnetic flux Φ2 in the opposite direction to the magnetic flux Φ1 generated by the direct current flowing in the coils 4 and 5 wound around the core 1, the direct current flowing in the coils 4 and 5 The generated magnetic flux is canceled by the amount of the magnetic flux supplied from the permanent magnets 6 and 7, magnetic saturation is prevented, and an inductance component capable of handling a large current can be provided.

  In addition, among the magnetic fluxes of the permanent magnets 6 and 7 forming each pair, the flow of the magnetic flux Φ3 in the same direction as the magnetic flux Φ1 generated by the direct current flowing through the coils 4 and 5 is reduced by the magnetic gap 2, so each pair is formed. The object that the permanent magnets 6 and 7 provide a reverse magnetic field can be effectively achieved.

  In the present invention, since the permanent magnets 6 and 7 are provided not on the magnetic path of the core 1 but on the surface of the core 1, the magnetic flux Φ 1 generated by the direct current flowing in the coils 4 and 5 causes the permanent magnets 6 and 7. Most of the permanent magnets 6 and 7 are not demagnetized.

  Moreover, since the permanent magnets 6 and 7 are provided on the surface of the core 1, it can be easily attached by pasting or the like, and can be retrofitted to existing inductance components.

Further, if a plurality of cores are combined to form a magnetic gap at each abutting portion, there will be difficulty in manufacturing for accurately setting the magnetic gap, but in the case of the present invention , the core 1 has one magnetic gap. Therefore, the magnetic gap 2 can be easily adjusted and manufactured easily.

  In the present invention, metal permanent magnets having high intrinsic coercive force such as Sm-Co can be used as the permanent magnets 6 and 7, but the permanent magnets 6 and 7 are also made of ferrite magnets. Even when used for a switching power supply that switches at a high frequency of 10 to 100 kHz or more, an inductance component with little core loss can be realized.

  Next, the results of experiments on the arrangement of the permanent magnets 6 and 7 in the inductance component of the present invention will be described. FIG. 2A is a conventional example in which no permanent magnet is provided on the core 1.

  2 (2) shows that the permanent magnets 6 and 7 are arranged at both ends of the leg portions 1d and 1e formed with the magnetic gap 2 so that the magnetic gap 2 of the core 1 is interposed between the permanent magnets 6 and 7. The generated magnetic flux φ2 is configured to be applied to the magnetic flux φ1 by a direct current flowing through the coils 4 and 5 (comparative example).

  In FIG. 2 (3), the permanent magnets 6, 7 are mounted at the same position, and the NS pole direction is opposite to that in FIG. 2 (2), so that the magnetic flux φ 2 of the permanent magnets 6, 7 is changed to the coils 4, 5. (Example) It is comprised so that the magnetic flux (phi) 1 generate | occur | produced with the direct current which flows into may be canceled.

  2 (4), the mounting position of the permanent magnets 6 and 7 is in the vicinity of the magnetic gap 2, and the magnetic flux φ2 of the permanent magnets 6 and 7 cancels out the magnetic flux φ1 generated by the direct current flowing through the coils 4 and 5. This is a configuration (Example).

As shown in FIG. 1, when the width g of the magnetic gap 2 is 12 mm, the width W of the core 1 is 83 mm, the height H is 90.5 mm, the coil winding portion width t = 14 mm, and the coil winding portion. The cross-sectional area was 196 mm ² . The width g of the magnetic gap 4 was 2 mm and 6 mm in addition to 12 mm.

  In addition, the bonding portion of the permanent magnets 6 and 7 to the core 1 was 14.42 mm × 14.54 mm, the length a = 18.42 mm, and the residual magnetic flux density Br was 220 mT.

  The number of turns of the coils 4 and 5 was 31 turns. Inductance was measured by superimposing an alternating current of 0.5 mA on coils 4 and 5 at a frequency of 1 kHz on various direct currents.

  Tables 1 and 3 show DC currents flowing through the coils in each of the configurations shown in FIGS. 2A to 2D when the width g of the magnetic gap 2 is 2 mm (in this case, the width of the core block 1c is also 2 mm). A change in inductance value L (μH) with respect to a change in Idc (A) is shown. In Table 1 and FIG. 3, Nomag is the configuration of FIG. 2 (1), mag is the configuration of FIG. 2 (2), rev-mag is the configuration of FIG. 2 (3), and max− rev is the configuration shown in FIG.

  As can be seen from the comparison of the curves (1), (2), and (3) in FIG. 3, when the permanent magnets 6 and 7 are not present (1), the permanent magnets 6 and 7 and the generated magnetic flux Φ2 are the coil 4 and When the magnetic flux Φ1 generated by the direct current flowing in the line 5 is canceled (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.

  Further, when the permanent magnets 6 and 7 are not provided (1), the permanent magnets 6 and 7 are supplied in a direction in which the generated magnetic flux Φ2 is added to the magnetic flux Φ1 generated by the direct current flowing through the coils 4 and 5 (2). In this case, as the direct current increases, magnetic saturation is promoted, and the obtained inductance L is lowered. Further, when the current value is considered to cause magnetic saturation, the inductance values of the two become substantially the same.

  As can be seen from the comparison of FIGS. 3 (3) and (4), which are the characteristics of the configurations of (3) and (4) in FIG. It can be seen that when the permanent magnets 6 and 7 are provided in the vicinity of the magnetic gap 2, the effect of suppressing the magnetic saturation is greater, and even when the value of the direct current Idc (A) increases, the decrease in the inductance value is small.

  Tables 2 and 4 show the inductance value with respect to the change of the direct current Idc (A) when the width g of the magnetic gap 2 is 6 mm (in this case, the width of the core block 1c is also 6 mm) in the configuration of FIG. The change of L (μH) is shown. Further, Tables 3 and 5 show the inductance with respect to the change in the direct current Idc (A) when the width g of the magnetic gap 2 is 12 mm (in this case, the width of the core block 1c is also 12 mm) in the configuration of FIG. The change of the value L (μH) is shown.

  As can be seen from the comparison of Tables 1 to 3 and FIGS. 3 to 5, the larger the width g of the magnetic gap 2, the lower the obtained inductance value, but the larger the width g of the magnetic gap 2. Even with a large direct current, a magnetic saturation suppressing effect can be obtained.

  Next, in the configuration of FIG. 2, when the width g of the magnetic gap 2 is 12 mm, as shown in FIG. 6, the permanent magnets 6 and 7 are not provided (1), and the permanent magnet 6 is only on one side of the magnetic gap 2. Alternatively, the embodiment (2), (3) of the present invention in which 7 is arranged, the embodiment (4) of the present invention in which the permanent magnets 6, 7 are provided on both sides, and the permanent magnet 9 is inserted instead of the magnetic gap 2. The same measurement was performed for Comparative Example (5). In any of the cases (2) to (5), either one or both of the permanent magnets 6 and 7 and the magnetic flux Φ2 of the permanent magnets 6 and 7 are permanently offset with respect to the magnetic flux Φ1 generated by the direct current flowing through the coils 4 and 5. Magnets 6 and 7 were provided in the vicinity of the magnetic gap 2.

Table 4 and FIG. 7 show changes in the inductance value L (μH) with respect to changes in the direct current Idc (A) in the respective configuration examples (1) to (5) in FIG. As can be seen from Table 4 and FIG. 7, when the permanent magnet 6 or 7 is provided on one side of the magnetic gap 2 of the core 1 (2) and (3), compared with the case where the permanent magnet 6 or 7 is not provided. Thus, a decrease in the inductance value with respect to an increase in DC current was suppressed. Further, when the permanent magnets 6 or 7 are provided on one side of the magnetic gap 2, when the permanent magnets 6 and 7 are provided (4), the magnetic saturation suppression effect is further increased as compared to (2) and (3). Compared with the cases of (2) and (3), it is possible to cope with an increase in DC current of about 2 A. Further, in the case of the conventional example (5), although the number of the permanent magnets 9 is one, the magnetic saturation suppression effect equivalent to that in the case of the embodiment (4) according to the present invention is obtained.

  FIG. 8 shows another embodiment of the present invention. This embodiment is an example in which the permanent magnets 6 and 7 are provided in the vicinity of the magnetic gap 2 on the inner peripheral side of the core 1. According to this embodiment, since the permanent magnets 6 and 7 are provided on the inner peripheral surface of the core 1, the permanent magnets 6 and 7 do not protrude from the outer peripheral surface of the core 1, and the inductance component can be reduced in size. .

  FIG. 9 shows another embodiment of the present invention. In this embodiment, the core block 1c is eliminated, and the lengths of the leg portions 1d and 1e on the gap forming side of the cores 1a and 1b to be combined are set on the bonding side. The leg portions 1f and 1g are shorter than the length, and the leg portions 1f and 1g are directly bonded (3) to form a magnetic gap 2 having a width corresponding to the difference in length. According to this embodiment, since the bonding portion 3 is provided at one place, the manufacturing is further facilitated. In this embodiment, the lengths of the leg portions 1d and 1e and the lengths of the leg portions 1f and 1g are not necessarily the same, but the lengths of the opposing leg portions are equal. In this case, there is an advantage that the cores 1a and 1b having the same shape can be used.

  When practicing the present invention, the core 1 may be formed by integral molding rather than combining two cores. FIG. 10 shows an example using the core 10 obtained by integral molding, and the magnetic gap 2 is formed by a gap.

  In the present invention, the core 11 may be formed in a circular shape as shown in FIG. Also in this case, the core 11 may be integrally formed or a plurality of cores may be combined by bonding or a magnetic gap material. 6 and 7 are permanent magnets provided on the outer periphery of the core 11 in the magnetic gap 2 of the core 11. The magnetic flux φ1 due to the direct current flowing through the coils 4 and 5 is canceled by the magnetic flux φ2 of the permanent magnets 6 and 7 by the amount of the magnetic flux φ2. Is done.

  Although the case where the inductance component is a choke coil has been described in the above embodiment, the present invention can also be applied to the case where the inductance component is a transformer.

It is a figure which shows one Embodiment of the inductance component by this invention. In order to investigate the demagnetization effect by the permanent magnet, the coil is wound around the core and the permanent magnet is not provided, and various configurations in which the permanent magnet is provided with various positions and polarities of the permanent magnet are shown. is there. 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 case the width | variety of a magnetic gap is 2 mm. 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 case the width | variety of a magnetic gap is 6 mm. 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 case the width | variety of a magnetic gap is 12 mm. In order to investigate the demagnetization effect by a permanent magnet, the figure which shows the various structure which provided the permanent magnet by setting the position and the number of a permanent magnet variously when winding a coil around a core and not providing a permanent magnet It is. In each example shown in FIG. 6, 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. It is a figure which shows other embodiment of the inductance component by this invention. It is a figure which shows other embodiment of the inductance component by this invention. It is a figure which shows other embodiment of the inductance component by this invention. It is a figure which shows other embodiment of the inductance component by this invention.

Explanation of symbols

1, 1a, 1b, 9, 10, 11: Core, 1c: Core block, 1d-1g: Leg part, 2: Magnetic gap, 3: Adhesion part, 4, 5: Coil, 6, 7: Permanent magnet

Claims (3)

An inductance component having a core for winding at least one coil for passing a direct current on which an alternating current is superimposed,
Form one magnetic gap in the ferrite core,
A pair of permanent magnets that supply a magnetic flux in a direction opposite to a magnetic flux generated by a direct current flowing in a coil wound around the ferrite core, so that the magnetic flux supplied by the permanent magnet passes through the coil winding portion of the core. One magnet is provided on the surface of the core in the vicinity of the magnetic gap so that the surface facing the surface and the opposite surface are opposite in polarity, and the other magnet has the magnetic gap between the one magnet and the other magnet. The core is provided on the surface of the core in the vicinity of the magnetic gap so as to be sandwiched between the one magnet and the polarity opposite to that of the one magnet so that the surface facing the surface and the opposite surface are opposite in polarity. An inductance component characterized by being provided on the surface of The inductance component according to claim 1 ,
An inductance component, wherein the permanent magnet is provided on an inner peripheral surface of the ferrite core. The inductance component according to claim 1 or 2 ,
An inductance component, wherein the permanent magnet is a ferrite magnet.

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