JP2003109832A - Magnetic core and inductance part using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inductance part using a magnetic core which can be provided easily and inexpensively having excellent direct current superposition characteristic and low loss characteristic. SOLUTION: The inductance part uses the magnetic core inserting and mounting a bond magnet comprising rare earth sintered magnet powder and a resin in a gap formed on a magnetic circuit of the magnetic core, is press-molded while an orientation magnetic field is applied in a sheet state formed by a printing method so that a value of a bias magnetic field generated by the bond magnet is 25-45% of saturated magnetization of the magnetic core. Since the degree of orientation of the bond magnet is increased and an electric resistive rate is improved, a core loss characteristic is more stably improved than the inductance part (conventional example) using the magnetic core without using the bond magnet. The inductance part is configured so that the direction of the bias magnetic field generated by the bond magnet is in a contrary direction to the direction of a winding magnetic field generated by supplying a direct current by a winding part, and its use is suitable under semi-excitation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mainly applied to choke coils and transformers for high-frequency switching power supplies, D / D converters, etc., and is also suitable for noise suppression components of DC power supply lines and under half-wave excitation in choke coils. The present invention relates to a magnetic core suitable for use and an inductance component using the magnetic core.

[0002]

2. Description of the Related Art Conventionally, magnetic cores used in choke coils and transformers have been required to have good DC superposition characteristics and low loss characteristics. A ferrite magnetic core made of a sintered body of NiZn-based ferrite or a powder magnetic core obtained by compression-molding a mixture of metal powder such as permalloy or sendust mixed with a binder made of epoxy resin is used. .

Generally, a ferrite magnetic core has a characteristic that the initial magnetic permeability is high and the saturation magnetic flux density is small, and a dust magnetic core has a characteristic that the initial magnetic permeability is low and the saturated magnetic flux density is high. Therefore, a magnetic core made of ferrite is often used as an EE core having a structure in which a magnetic permeability of the magnetic core is lowered by providing a gap between the middle legs of a pair of E-shaped cores and abutting each other to make magnetic saturation difficult, The dust core is often used as a toroidal shape with no gap in the magnetic path.

Even in the field of development of magnetic cores using such magnetic cores, it is indispensable to carry out miniaturization of electronic parts in accordance with miniaturization of electronic parts in response to recent demands for miniaturization of electronic equipment. However, in such miniaturization, it is strongly demanded that the magnetic characteristics have higher magnetic permeability and lower loss with a larger superimposed magnetic field.

Usually, in order to improve the direct current superposition characteristic, it is necessary to select a magnetic core having a high saturation magnetization, that is, a magnetic core which is not magnetically saturated in a high magnetic field. Since it is inevitably determined by the composition of the material and cannot be increased indefinitely, a large amount of labor has been conventionally spent to achieve a slight improvement in saturation magnetization. The current situation is that the DC superimposition characteristics have not expanded as much as expected.

As a means for solving such a problem, there has been a method of forming a magnetic core by forming a gap at one or more places of a magnetic path in a magnetic core and inserting and mounting a permanent magnet into one of the gaps. Is being considered. In the case of the magnetic core having such a configuration, the result for improving the DC superposition characteristic can be obtained, but on the other hand, for example, when a metal sintered magnet is used as the permanent magnet, the core loss of the magnetic core is significantly increased. The present situation is that no magnet having magnetic characteristics that can withstand practical use has been obtained, since problems such as looseness or the use of ferrite magnets may cause the DC superposition characteristics to become unstable.

Therefore, as means for solving such a problem, for example, in the technique disclosed in Japanese Patent Laid-Open No. 50-133453, a rare earth magnet having a high coercive force is used as a permanent magnet inserted and mounted in a gap of a magnetic core. It has been proposed to use a bond magnet obtained by mixing powder and a binder and then compression-molding the mixture, and it is possible to improve the DC superposition characteristics and the temperature rise of the magnetic core by such a configuration.

[0008]

SUMMARY OF THE INVENTION A magnetic core using a bond magnet obtained by mixing a rare earth magnet powder having a high coercive force and a binder in a permanent magnet inserted and mounted in the gap of the magnetic core and then compression-molding the mixture. In this case, the DC superposition characteristics are certainly improved, but the demands for the improvement of the power conversion efficiency for the recent high frequency switching power supplies are becoming more severe, or choke coils and transformers are required. Even if the temperature of the magnetic core used is simply measured, the superiority or inferiority of the magnetic properties is considered to be undecidable, and the excellent core loss property is also considered to be an indispensable criterion. In consideration of the current situation, the core loss characteristic is inferior at the disclosed resistivity value according to the result of actually measuring the core loss characteristic with the core loss measuring device. There is a problem that is has to.

In the case of a switching power source, for example, a switching loss is caused by a delay in rising / falling of a current / voltage waveform in a switching transistor, a diode loss such as a flywheel diode, and a choke. Examples include iron loss of magnetic parts such as coils and transformers. Among these, as a measure for improving the power conversion efficiency of a power supply in recent years, for switching loss, a current-voltage waveform is converted into a sine wave (sine wave) by using a resonance phenomenon, so The resonance method that suppresses the loss by reducing the overlap of the current and voltage waveforms is adopted.
The synchronous rectification method in which the diode part is replaced by T is adopted, but there is no effective measure for iron loss of magnetic parts, and at present, there is no choice but to resort to improvement of loss characteristics of magnetic materials. It is difficult to improve.

The present invention has been made to solve such a problem, and its technical problem is to have excellent direct current superposition characteristics and lower loss characteristics than conventional ones, which can be easily and inexpensively. It is to provide a magnetic core that can be provided and an inductance component using the magnetic core.

[0011]

According to the present invention, a bond magnet made of rare earth sintered magnet powder and a resin or a rare earth sintered material is used for a gap in a magnetic core having a gap at at least one place in a magnetic path. A magnetic core is obtained by inserting and mounting at least one of a magnet and a composite magnet made of resin, and the value of the bias magnetic field generated by the bond magnet or the composite magnet is 25 to 45% of the saturation magnetization of the magnetic core. To be

Further, according to the present invention, in the magnetic core, the rare earth sintered magnet powder or the rare earth sintered magnet has an intrinsic coercive force _I H _C of 3.95 × 10 ⁶ A / m or more and a Curie temperature T _C. A magnetic core having a temperature of 300 ° C. or higher is obtained.

Further, according to the present invention, there can be obtained an inductance component including a winding portion formed by winding at least one turn of winding on any one of the above magnetic cores.

In addition, according to the present invention, in the above-mentioned inductance component, the direction of the bias magnetic field generated by the bond magnet or the composite magnet is opposite to the direction of the winding magnetic field generated by the supply of the direct current in the winding portion. An inductance component that is set to be oriented can be obtained.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the magnetic core of the present invention and an inductance component using the same will be given below.
A detailed description will be given with reference to the drawings.

First, the technical outline of the magnetic core of the present invention will be briefly described. The magnetic core of the present invention is a bonded magnet composed of a rare earth sintered magnet powder and a resin, or a composite magnet composed of a rare earth sintered magnet and a resin, with respect to a gap in a magnetic core having a gap in at least one location of a magnetic path. It is configured by inserting and mounting at least one of
The value of the bias magnetic field generated by these bonded magnets or composite magnets is 25 to 45% of the saturation magnetization of the magnetic core. However, in this magnetic core, the rare earth sintered magnet powder and the rare earth sintered magnet have an intrinsic coercive force _I H _C of 3.95.
A material having a Curie temperature T _C of 300 ° C. or more at a density of × 10 ⁶ A / m or more is used.

For any of such magnetic cores, an inductance component can be obtained by providing a winding portion formed by winding a winding wire of at least one turn. However, in this inductance component, the direction of the bias magnetic field generated by the bond magnet or the composite magnet is set to be opposite to the direction of the winding magnetic field generated by the DC current supplied in the winding portion. There is a need.

Therefore, the technical background of the process leading to the research and development of the present invention will be described below. The inventors of the present invention have a structure in which a permanent magnet is inserted and attached to a gap in a magnetic core having a gap at one or more places of a magnetic path as a magnetic core having a conventional structure, and the permanent magnet is inserted and attached to give a magnetic bias. As a result of investigating the magnet, a bond magnet made of a rare earth sintered magnet powder and a resin having an intrinsic coercive force _I H _C of 3.95 × 10 ⁶ A / m or more, or a composite magnet made of a rare earth sintered magnet and a resin (also Intrinsic coercive force _I H _C is 3.95
It was found that the hysteresis loss generated in the magnet part is reduced by using a mixture of rare earth sintered magnet powder of × 10 ⁶ A / m or more and a resin to obtain a magnet body and then drying. Particularly, in the case of a bonded magnet, press forming is performed while applying an orientation magnetic field in a sheet state formed by a printing method, and in the case of a composite magnet, a magnet body is manufactured by a printing method and then dried while applying an orientation magnetic field. As a result, it was discovered that the orientation degree of the magnet is increased, the electrical resistivity is improved, and the hysteresis loss generated in the magnet portion can be reduced. Moreover, when such a magnetic core is applied to noise suppression components for DC power supply lines, choke coils, inductance components used under half-wave excitation such as forward type transformers and flyback type transformers, the magnets in the winding part In addition to reducing the eddy current loss in the magnet part that is generated by the winding magnetic field that is interlinking with the winding magnetic field, the direction of the bias magnetic field that is generated by the bond magnet or the composite magnet is the winding magnetic field that is generated when the direct current is supplied to the winding part. By setting so that the winding magnetic field due to the winding portion and the magnetic field due to the magnet cancel each other, the magnetic core hardly causes magnetic saturation, and the bias magnetic field due to the magnet is reduced. Excellent DC superposition characteristics and low loss characteristics are obtained due to the existence of
It was found that the maximum value of the magnetic field becomes lower than the maximum value of the magnetic field reached by normal half-wave excitation, and the core loss becomes lower accordingly. On the other hand, in addition to the primary and secondary windings that are usually used for core loss measurement, a tertiary winding is used for a toroidal core made of MnZn ferrite, and a DC current is applied to this tertiary winding. As a result, core loss measurement was performed under the condition that a DC magnetic field was generated, and it was confirmed that when the DC magnetic field increased and the maximum value of the reaching magnetic field increased, the core loss also increased.

In the case of an inductance component used under normal half-wave excitation, the state of the magnetic field generated during operation is unevenly distributed only in the first quadrant when represented by the BH plane, and its maximum value is, for example, that of a ferrite core. In this case, it is 200 to 400 mT in order not to saturate the core. That is, since a magnetic field in the range of 0 mT to 250 to 400 mT is generated in the core, the maximum value of the magnetic field is made lower than the maximum value of the magnetic field reached by normal half-wave excitation by the bias magnetic field of the magnet. To do this, set the bias magnetic field by the magnet to 1
It is preferably 25 to 200 mT. If the bias magnetic field is lower than this, a sufficient bias cannot be obtained. On the contrary, if the bias magnetic field is too high, the magnetic field on the opposite side becomes high and core loss increases. Incidentally, the saturation magnetization of the ferrite core is about 450 mT, and the ratio of the bias magnetic field by the magnet to the saturation magnetization is 25 to 45% of the saturation magnetization.

As a magnet having a high intrinsic coercive force _I H _C , a rare earth magnet powder or a rare earth bonded magnet which is a composite magnet formed by mixing rare earth magnet powder with a binder is generally used. It may have such a composition. As a kind of rare earth magnet powder, S
Any of mCo type, Nd-Fe-B type, and Sm-Fe-N type may be used, and the magnitude of the residual magnetization of the powder determines the bias magnetic field, and the value of the coercive force determines the stability of magnetic characteristics. Therefore, the type of magnet powder can be selected according to the type of magnetic core.

In particular, as the magnetic material applied to the magnetic core for the choke coil or the transformer, any material having a soft magnetic property may be used, and the magnetic material may be Mn-Zn type or N type.
i-Zn ferrite, dust core, silicon steel plate, amorphous and the like are generally used. However, considering that the larger the magnetic permeability of the core, the more easily the bias effect is obtained, Mn
It is preferable to use a material having a magnetic permeability of 2000 or more, such as —Zn-based ferrite, silicon steel sheet, or amorphous.

The shape of the magnetic core is not particularly limited, and any shape such as a toroidal core, EE type core or EI type core can be applied. The gap length provided in the magnetic path of the magnetic core is not particularly limited, but if the gap length is too narrow, it becomes difficult to obtain the desired DC superposition characteristics, and if the gap length is too wide, the magnetic permeability decreases too much and the desired inductance is reduced. Since it becomes difficult to obtain a value, the gap length is naturally determined if care is taken to prevent such disadvantages. However, regarding the magnetic characteristics required for the bonded magnet or the composite magnet inserted in the gap, the intrinsic coercive force _I H _C is 3.95 × 10 ⁶ A
If it is less than / m, the coercive force will be lost by the DC magnetic field applied to the magnetic core, and therefore a value higher than that value is necessary.

When it is used as a product, it may be exposed to a temperature condition of 200 to 270 ° C. at the time of reflow of soldering, so that in such a case, the Curie temperature T should not be lost. _C is preferably 300 ° C. or higher.

The magnetic cores and the inductance components using the magnetic cores will be specifically described below, including some manufacturing steps, by taking some examples.

Example 1 In Example 1, first, as the rare earth magnet powder, an aromatic polyamide in an amount corresponding to a total volume ratio of 20 vol% with respect to Sm ₂ Fe ₁₇ N magnet powder having an average particle size of about 3 μm. A resin (6T nylon) was heat-kneaded under a condition of 300 ° C. in an Ar atmosphere using a Labo Plastomill, and then hot press molded in an orientation magnetic field of 1.5T to produce a sheet having a thickness of 100 μm. .

Next, this sheet and a resin film having a film thickness of 10 μm are alternately laminated to form a layer, and hot press molding is performed again to obtain a plate-shaped body having a thickness of 11 mm. A plate-shaped bond magnet that matches the cross-sectional shape of the core of the magnetic core is obtained by cutting it to a size of 10.6 mm × 7.0 mm × 1.5 mm after cutting it with a size of 1.5 mm perpendicular to It was made.

Further, the bond magnet manufactured here is inserted and mounted in the gap in the magnetic core to manufacture a magnetic core, and then a winding is wound around the magnetic core to provide a winding portion, thereby forming an inductance component. Was produced. However, in this inductance component, the direction of the bias magnetic field generated by the bond magnet is set to be opposite to the direction of the winding magnetic field generated by the supply of the direct current in the winding portion.

Therefore, the inductance component according to the first embodiment, which is manufactured so as to have a magnetic core formed by inserting and mounting a bond magnet in the gap of the magnetic core, is the same as the inductance component according to the first embodiment except that the bond magnet is not inserted and mounted in the gap of the magnetic core. For the comparative inductance component manufactured by the above procedure, the frequency f = 100 kHz and the magnetic flux density B _m = 0.0.0 at room temperature were measured using a SY8232 AC BH analyzer manufactured by Iwasaki Tsushinki.
The core loss characteristics are examined by measuring the core loss value P _CV (kW / m ³ ) under the condition of 1T, and the AC loss is 1 kHz in the range of 1 kHz to 15 MHz using a Hewlett Packard 4194A impedance analyzer.
Ratio μ (10 MHz) / μ of permeability μ (10 MHz) at 10 MHz to permeability μ (1 kHz) at kHz
When the frequency characteristics were investigated by measuring (1 kHz), the core loss value _PCV was 150 and the ratio μ (10 MHz) / μ (1
kHz) is 0.95, and in the case of the inductance component for comparison, the core loss value P _CV is 230 and the ratio μ (10 MH).
z) / μ (1 kHz) was 0.75.

As a result, it can be seen that the inductance component (magnetic core) according to the first embodiment has improved frequency characteristics as compared with the comparative inductance component (magnetic core).
This is because the eddy current radius is reduced by inserting and mounting the layered bond magnet, which reduces the eddy current loss and the core loss.

For the inductance component according to the first embodiment and the inductance component for comparison, the superimposed magnetic field H _m
100 kHz under the condition that (A / m) is changed and applied
When the negative value of the magnetic permeability μ (100 kHz) at the time was measured and the change of the core loss characteristics due to the superposed magnetic field H _m was examined, FIG.
The result is shown in.

From FIG. 1, it can be seen that in the case of the inductance component according to the first embodiment, the core loss characteristic is more stably improved than the inductance component for comparison (conventional example). This is because the orientation degree of the bond magnet is increased and the electrical resistivity is improved by performing press molding while applying the orientation magnetic field during the production of the bond magnet, which can reduce the hysteresis loss generated in the magnet portion.

Example 2 In Example 2, first, Sm ₂ Fe ₁₇ N based sintered magnet powder having an average particle size of about 3 μm as rare earth magnet powder, soluble polyimide resin, and γ-butyrolactone as a solvent were used. Mix and stir with a centrifugal defoamer for 7 minutes to prepare a paste, and use this paste to prepare a green sheet with a doctor blade method to a thickness of 300 μm, and then in a 1.5T orientation magnetic field. After being dried in, a hot press molding was performed to prepare a sheet having a film thickness of 150 μm.

Next, this sheet was cut to have a cross-sectional shape of the core of the magnetic core in the same manner as in Example 1, and about 10
1.5m thick after magnetized in the magnetic path direction with a pulsed magnetic field of T
A composite magnet having a laminated structure was produced by stacking the composite magnets so that the composite magnet had a thickness of m.

Further, this composite magnet was inserted and mounted in the gap in the magnetic core to produce a magnetic core, and then a winding was wound around this magnetic core to provide a winding portion to produce an inductance component. However, in this inductance component, the direction of the bias magnetic field generated by the composite magnet is set to be opposite to the direction of the winding magnetic field generated by the supply of the direct current in the winding portion.

Therefore, the inductance component according to the second embodiment, which is manufactured so as to have a magnetic core formed by inserting and mounting the composite magnet in the gap of the magnetic core, is the same as that of the inductance component except that the composite magnet is not inserted and mounted in the gap of the magnetic core. With respect to the comparative inductance component manufactured by the above procedure, the winding magnetic field H was obtained by using TDF-5AH DC BH tracer manufactured by Toei Industry.
Magnetic flux density B _m (T) for _m (± 11850 A / m)
Comparing the states of the BH loop indicated by the relationship
The results are shown in FIG.

From FIG. 2, focusing on the first quadrant of the BH loop plane, in the inductance component of the second embodiment, the maximum value of the winding magnetic field H _m generated by the winding current due to the bias magnetic field of the composite magnet is the inductance for comparison. It can be seen that the height is lower than that of the case of the parts (conventional example). This is because, in the first quadrant, the winding magnetic field H _m generated by the winding current and the bias magnetic field generated by the composite magnet are in opposite directions and cancel each other.
Further, focusing on the third quadrant of the BH loop plane, conversely, in the inductance component of the second embodiment, the winding magnetic field H _m generated by the winding current and the bias magnetic field generated by the composite magnet are strengthened in the same direction. It can be seen that the maximum value of the winding magnetic field H _m generated by the reaching winding current is larger than that of the comparative inductance component.

Due to the amount of displacement of the BH loop, in the case of the inductance component of the second embodiment, the bias amount obtained by the composite magnet is about 170 mT, and the saturation magnetization 3
It can be seen that it is 44% of 90 mT.

Regarding the inductance component according to the second embodiment, HP4284A manufactured by Hewlett-Packard.
LCA meter (indicating the magnetic flux density) superimposed magnetic field of an alternating magnetic field frequency 100kHz using was measured DC bias characteristics in relation to the core loss value P _CV (kW ³⁾ for Bd _C (mT), as shown in FIG. 3 It was a result.

It can be seen from FIG. 3 that in the case of the inductance component according to the second embodiment, the core loss value P _CV gradually increases as the superposed magnetic field Bd _C increases, and excellent DC superposition characteristics can be obtained. .

By the way, the inductance component having the structure according to the second embodiment can be applied as, for example, a power transformer of a current resonance type forward power supply circuit using a synchronous rectification method. FIG. 4 shows the current resonance in such a case. 1 shows a basic configuration of a mold forward power supply circuit. That is, in this current resonance type forward power supply circuit, the second embodiment
In addition to mounting the inductance component having the configuration according to the above as the forward type power supply transformer 1 and using the FET 3 as a circuit configuration, the electronic load device 2 is used as a load so that the output current I _out and the input voltage V _in can be changed. Has become.

FIG. 5 shows the output current I of the forward type power transformer 1 using the inductance component having the structure according to the second embodiment of the current resonance type forward power circuit.
The state of the efficiency η (%) (output current-efficiency characteristic) when _out (A) is changed is shown in comparison with the configuration (conventional example) in which an inductance component for comparison is substituted. .

Further, FIG. 6 shows the efficiency η (in the case of changing the input voltage V _in (V) _in the forward type power transformer 1 using the inductance component having the configuration according to the second embodiment in this current resonance type forward power circuit. %) (Input voltage-efficiency characteristic) in comparison with a configuration (conventional example) in which an inductance component for comparison is substituted.

From FIGS. 5 and 6, in the case of the forward type power transformer 1 using the inductance component having the configuration according to the second embodiment, the inductance for comparison is changed _{regardless of} whether the output current I _out or the input voltage V _in is changed. It was found that the efficiency was improved by about 3% as compared with the case where the parts were substituted, and the basic characteristics as the transformer were improved.

In the case of the inductance component of the second embodiment, the effectiveness when it is specifically applied as the power transformer of the current resonance type forward power supply circuit is shown.
Substantially the same effect can be obtained by substituting the above inductance component, and any inductance component can be applied to other choke coils and the like, so the present invention is not limited to those disclosed in the respective embodiments.

[0045]

As described above, according to the magnetic core of the present invention, with respect to the gap formed in the magnetic path of the magnetic core,
At least one of a bond magnet made of rare earth sintered magnet powder and resin or a composite magnet made of rare earth sintered magnet and resin is inserted and mounted, and the value of the bias magnetic field generated by the bond magnet or the composite magnet is the saturation magnetization of the magnetic core. 25 to 4
In the case of a bonded magnet, press molding is performed while applying an orientation magnetic field in the state of a sheet formed by a printing method so that the content becomes 5%, and in the case of a composite magnet, an orientation magnetic field is produced after a magnet body is produced by a printing method. Since it is dried while adding the magnet, the degree of orientation of the magnet is increased, the electric resistivity is improved, and the hysteresis loss generated in the magnet part is reduced. In addition, rare earth sintered magnet powder or rare earth sintered magnet is used. Since it has a configuration in which the intrinsic coercive force and Curie temperature of the are properly determined, it has excellent DC superposition characteristics and low loss characteristics,
Moreover, it can be provided easily and inexpensively. In addition, in an inductance component in which a winding portion is provided on this magnetic core, the direction of the bias magnetic field generated by the bond magnet or the composite magnet is opposite to the direction of the winding magnetic field generated by the DC current supplied to the winding portion. The winding magnetic field due to the winding and the magnetic field due to the magnet cancel each other out, which makes it difficult for the magnetic core to undergo magnetic saturation, resulting in excellent DC superposition characteristics due to the presence of the bias magnetic field due to the magnet. And low loss characteristics can be obtained, the maximum value of the magnetic field becomes lower than the maximum value of the magnetic field reached by normal half-wave excitation, and the core loss can be reduced accordingly, so that especially the DC power line It is suitable to use under half-wave excitation in noise suppression parts and choke coils.

[Brief description of drawings]

FIG. 1 is a negative value of a magnetic permeability at 100 kHz in a state in which a superposed magnetic field is changed and applied to an inductance component manufactured by using a magnetic core according to a first embodiment of the present invention and a comparative inductance component. It shows a change in core loss characteristics due to a superposed magnetic field, which is shown by the result of measurement.

FIG. 2 is a comparison of the states of a BH loop shown by the relationship of the magnetic flux density with respect to the winding magnetic field, between an inductance component manufactured using the magnetic core according to the second embodiment of the present invention and a comparative inductance component. It is shown.

FIG. 3 shows a comparison result of measuring the DC superposition characteristics shown by the relationship of the core loss value to the superposition magnetic field at an AC magnetic field frequency of 100 kHz for the inductance component according to the second embodiment described in FIG.

FIG. 4 is a diagram showing a basic configuration of a current resonance type forward power supply circuit using a synchronous rectification method in which an inductance component having a configuration according to the second embodiment described in FIG. 2 is mounted as a transformer.

5 shows a state of efficiency (output current-efficiency characteristic) when the output current is changed in the forward power supply transformer using the inductance component having the configuration according to the second embodiment in the current resonance type forward power supply circuit shown in FIG. It is shown in comparison with a configuration in which a comparative inductance component is substituted.

FIG. 6 shows a state of efficiency (input voltage-efficiency characteristic) when the input voltage is changed in the forward power supply transformer using the inductance component having the configuration according to the second embodiment in the current resonance type forward power supply circuit shown in FIG. It is shown in comparison with a configuration in which a comparative inductance component is substituted.

[Explanation of symbols]

1 Forward type power transformer 2 electronic loader 3 FET

Claims (4)

[Claims] 1. A bonded magnet composed of a rare earth sintered magnet powder and a resin, or a composite magnet composed of a rare earth sintered magnet and a resin, for the gap in a magnetic core having a gap at least at one or more locations in a magnetic path. At least one is inserted and mounted, and the value of the bias magnetic field generated by the bond magnet or the composite magnet is 25 to 4 of the saturation magnetization of the magnetic core.
A magnetic core characterized by being 5%. 2. The magnetic core according to claim 1, wherein the rare earth sintered magnet powder or the rare earth sintered magnet has an intrinsic coercive force _I H _C of 3.95 × 10 ⁶ A / m or more and a Curie temperature T _C. Is 300 ° C. or higher, a magnetic core. 3. An inductance component, comprising: a winding portion formed by winding a winding wire of at least one turn around the magnetic core according to claim 1 or 2. 4. The inductance component according to claim 3, wherein a direction of a bias magnetic field generated by the bond magnet or the composite magnet is opposite to a direction of a winding magnetic field generated by supplying a direct current to the winding portion. An inductance component characterized by being set so as to be oriented.