JP2008192897A - Dust core and reactor - Google Patents
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Abstract
Description
本発明は、高周波抑制のためのパワーファクターコレクション（ＰＦＣ）や、ノーマルモードチョークやパワーチョーク、その他、ハイブリッド自動車の大出力の電気モータを駆動するような電源回路に用いられるリアクトルに用いられる圧粉磁心に関するものである。 The present invention relates to power factor collection (PFC) for suppressing high frequency, normal mode choke, power choke, and other compacts used for a reactor used in a power circuit for driving a high output electric motor of a hybrid vehicle. It is about magnetic core.
電源回路用磁心として主に３種類の磁心が用いられる。数十ｋＨｚ以下の領域では、珪素鋼板、非晶質軟磁性帯板、微結晶質軟磁性帯板などが磁心材として主に用いられている。これらの磁心材は鉄を主成分とし、飽和磁束密度Bｓと比透磁率μｒが大きいという長所をもつ。しかしながら、珪素鋼板は高周波磁心損失が大きいという欠点を有し、非晶質軟磁性帯板と微結晶質軟磁性帯板は、磁心形状が巻磁心形状や積層磁心形状などに制約され、後述するフェライトのように種々の形状に成形し難い欠点を有する。
また、数十ｋＨｚ以上の領域では、Ｍｎ-Ｚｎ系やＮｉ-Ｚｎ系に代表されるフェライト磁心が広く用いられている。このフェライト磁心は、高周波磁心損失が小さく、また成形が比較的容易なため、種々の形状を大量生産できる特長を有する。しかしながら、飽和磁束密度Bｓが前述の珪素鋼板や非晶質軟磁性帯板、微結晶質軟磁性帯板の３分の１から２分の１程度しかないため、磁気飽和を避けるようとすると磁心断面積が大きくなるという欠点を有する。
Three types of magnetic cores are mainly used as power circuit magnetic cores. In the region of several tens of kHz or less, silicon steel plates, amorphous soft magnetic strips, microcrystalline soft magnetic strips, etc. are mainly used as magnetic core materials. These magnetic core materials are mainly composed of iron, and have an advantage that the saturation magnetic flux density Bs and the relative permeability μr are large. However, silicon steel plates have the disadvantage that high frequency magnetic core loss is large, and amorphous soft magnetic strips and microcrystalline soft magnetic strips have a magnetic core shape that is constrained by a wound core shape or a laminated core shape, which will be described later. It has a drawback that it is difficult to form into various shapes like ferrite.
In the region of several tens of kHz or more, ferrite cores typified by Mn—Zn and Ni—Zn are widely used. Since this ferrite core has a small high-frequency core loss and is relatively easy to mold, it has the feature that various shapes can be mass-produced. However, the saturation magnetic flux density Bs is only about one-third to one-half that of the aforementioned silicon steel plate, amorphous soft magnetic strip, and microcrystalline soft magnetic strip. There is a disadvantage that the cross-sectional area becomes large.
数ｋHｚから数百ｋHｚまでの領域に用いられる磁心として圧粉磁心がある。圧粉磁心は、磁性粉末の表面を絶縁処理したのち加工成形したもので、絶縁処理により渦電流損失の発生が抑制されている。そのため、圧粉磁心の高周波磁心損失は珪素鋼板に比べると小さいという長所を持つ。 There is a dust core as a magnetic core used in the region from several kHz to several hundred kHz. The dust core is formed by subjecting the surface of the magnetic powder to insulation treatment and then processing, and generation of eddy current loss is suppressed by the insulation treatment. For this reason, the high frequency magnetic core loss of the dust core is small compared to the silicon steel sheet.
急速に普及しはじめたハイブリッド自動車では、大出力の電気モータを有しており、これを駆動する電源回路には高電圧大電流に耐えうるリアクトルが必要になる。このリアクトルには小型化、低騒音化、低損失化、耐久性の要求が強く、リアクトルに用いられる磁心材の特性としては、高い飽和磁束密度Bｓ、適切な範囲の比透磁率μｒ、高機械的強度、そして低騒音化のために磁化した時の体積変形率が低いものであることが要求される。 A hybrid vehicle that has begun to spread rapidly has a high-output electric motor, and a power circuit for driving the motor requires a reactor that can withstand a high voltage and a large current. There is a strong demand for miniaturization, low noise, low loss, and durability for this reactor. The characteristics of the magnetic core material used for the reactor include a high saturation magnetic flux density Bs, an appropriate range of relative permeability μr, and a high machine. It is required that the volume deformation rate when magnetized is low in order to reduce the mechanical strength and noise.
大電流用のリアクトル磁心として前述の圧粉磁心を用いたものがある。珪素鋼板、非晶質軟磁性帯板、微結晶質軟磁性帯板などの軟磁性帯板は透磁率が５００〜５０００程度であるが、圧粉磁心は１０〜２００程度であるため、軟磁性帯板に比べてギャップを少なくすることができる。この場合、フリンジング磁束が、軟磁性帯板に比べて少ないため、コイルに生じる渦電流を抑えることができる。そして、磁心損失の小さい圧粉磁心を用いることによりリアクトル損失を小さくできる。また、圧粉磁心は飽和しにくいので、大電流時に高透磁率が得られるという利点がある。 As a reactor core for large current, there is one using the above-mentioned dust core. Soft magnetic strips such as silicon steel plates, amorphous soft magnetic strips, and microcrystalline soft magnetic strips have a magnetic permeability of about 500 to 5000, but a dust core has a magnetic core of about 10 to 200. The gap can be reduced compared to the strip. In this case, since the fringing magnetic flux is smaller than that of the soft magnetic strip, the eddy current generated in the coil can be suppressed. The reactor loss can be reduced by using a dust core having a small magnetic core loss. In addition, since the dust core is not easily saturated, there is an advantage that a high magnetic permeability can be obtained at a large current.
低騒音を示す圧粉磁心として、特許文献１及び特許文献２が開示されている。特許文献１では、硬さと強度を向上させることにより、騒音を抑制している。また、特許文献２では、圧粉磁心を構成する粉末の粒径を制御することにより、騒音を抑制している。また、特許文献３では、Ｆｅ−１％Ｓｉ粉末とＦｅ−６．５％Ｓｉ粉末を混合して圧粉磁心とすることが開示されている。
例えば大電流用リアクトルの磁心として圧粉磁心を用いる場合、高い機械的強度、低騒音、かつ磁気特性の何れも優れたものを得ることは難しい。これは、リアクトルの駆動時に発生する騒音、長時間駆動させても特性が劣化しない耐久性を得るための機械的強度が粉末の合金組成、粒径、被覆する絶縁材の種類や量、そして圧粉体の空隙率などに大きく依存し、お互いがトレードオフの関係になることが多いためである。
本発明の課題は、これら圧粉磁心の問題点を解決し、従来よりも低騒音、かつ長時間駆動させても特性が劣化し難い圧粉磁心、特にリアクトル用磁心として有用な圧粉磁心を提供することである。
For example, when a dust core is used as the magnetic core of a high current reactor, it is difficult to obtain a high mechanical strength, low noise, and excellent magnetic characteristics. This is because the noise generated when the reactor is driven, the mechanical strength to obtain the durability that does not deteriorate the characteristics even if it is driven for a long time, the alloy composition of the powder, the particle size, the type and amount of the insulating material to be coated, and the pressure This is because it largely depends on the porosity of the powder and the like and often has a trade-off relationship.
An object of the present invention is to solve these problems of dust cores, and to provide a dust core that is lower in noise than conventional and whose characteristics are not easily deteriorated even if driven for a long time, in particular, a dust core useful as a core for a reactor. Is to provide.
本発明の圧粉磁心は、５〜８重量％のＳｉを含むＦｅ−Ｓｉ系合金粉末と９９．５質量％超がＦｅの純Ｆｅ粉末が混合されたことを特徴とする。 The dust core of the present invention is characterized in that a Fe—Si alloy powder containing 5 to 8% by weight of Si and a pure Fe powder containing more than 99.5% by mass of Fe are mixed.
この純Fe粉末の全体に対する重量比率が１０〜５５％の範囲にあるものが好ましい。 What the weight ratio with respect to the whole of this pure Fe powder exists in the range of 10-55% is preferable.
また、Ｆｅ−Ｓｉ系合金粉末はアスペクト比が２以下の球状であり、かつ、純Fe粉末はアスペクト比が２超の偏平状であるものが好ましい。 Moreover, it is preferable that the Fe—Si-based alloy powder has a spherical shape with an aspect ratio of 2 or less, and the pure Fe powder has a flat shape with an aspect ratio of more than 2.
Ｆｅ−Ｓｉ系合金粉末は平均粒径が５０〜１００μｍであり、かつ、純Ｆｅ粉末は平均粒径が１０〜５０μｍであるものが好ましい。 The Fe—Si-based alloy powder preferably has an average particle size of 50 to 100 μm, and the pure Fe powder preferably has an average particle size of 10 to 50 μm.
本発明の圧粉磁心は、磁化を飽和させたときの体積変形率が３ｐｐｍ以下であるが特徴である。また、圧環強度に換算した機械的強度が３０ＭＰa以上である。 The dust core of the present invention is characterized in that the volume deformation rate when the magnetization is saturated is 3 ppm or less. Further, the mechanical strength converted to the crushing strength is 30 MPa or more.
また、本発明はこれらの圧粉磁心を用いてリアクトルとすることができる。 Moreover, this invention can be made into a reactor using these powder magnetic cores.
本発明は、Ｆｅ−Ｓｉ系合金粉末と９９．５質量％超がＦｅの純Ｆｅ粉末を混合して圧粉磁心とすることで、高い機械的強度、低騒音、かつ磁気特性に優れた圧粉磁心を得ることができる。また、純Fe粉末の重量比率や、Ｆｅ−Ｓｉ系合金粉末と純Fe粉末のアスペクト比、両粉末の平均粒径を所定の値にすることで、機械的強度、低騒音、かつ磁気特性がさらに優れた圧粉磁心とすることができる。また、磁化を飽和させたときの体積変形率が４ｐｐｍ以下、圧環強度に換算した機械的強度が５０ＭＰａ以上の圧粉磁心が得られるので、これらの圧粉磁心を交流磁界中で動作させた時の騒音を抑制することができ、長時間駆動させても特性が劣化し難い。 The present invention mixes Fe-Si alloy powder and pure Fe powder of more than 99.5% by mass to form a powder magnetic core, so that the pressure is excellent in high mechanical strength, low noise, and magnetic characteristics. A powder magnetic core can be obtained. In addition, by setting the weight ratio of pure Fe powder, the aspect ratio of Fe-Si based alloy powder and pure Fe powder, and the average particle size of both powders to predetermined values, mechanical strength, low noise, and magnetic properties can be obtained. Furthermore, it can be set as the outstanding powder magnetic core. In addition, since a powder magnetic core having a volume deformation rate of 4 ppm or less when the magnetization is saturated and a mechanical strength converted to a compression ring strength of 50 MPa or more is obtained, when these powder magnetic cores are operated in an alternating magnetic field, Noise can be suppressed, and the characteristics hardly deteriorate even when driven for a long time.
本発明では、圧粉磁心が磁化された時の体積変形率に着目した。磁化された時の体積変形率とは、磁化されていない時の圧粉体の磁路方向長さをＬ0とし、磁化された時の圧粉体の磁路方向長さをＬ1としたとき、（Ｌ1−Ｌ0）÷Ｌ0で表される値である。
圧粉磁心が磁化される場合、磁路方向に吸引力が働き、この吸引力により圧粉磁心は体積が変形する。この体積変形率が大きい場合、この変化が空気に伝播し、高騒音をもたらす。逆に、この体積変形率が小さい場合は低騒音となる。体積変形率と１種類の粉末により構成される圧粉磁心の機械的特性の相関を調べた結果、この体積変形率は、圧粉磁心の硬さや強度、圧粉磁心を構成する粉末粒径との関係性は小さく、主に圧粉磁心のヤング率及び軟磁性粉末単体の飽和磁歪λｓに大きく依存することを見出した。ヤング率が高く、軟磁性粉末単体の飽和磁歪λｓが小さい程、体積変形率は小さくなる。しかしながら、５〜８重量％のＳｉを含むＦｅ−Ｓｉ系合金粉末などは、軟磁性粉末単体の飽和磁歪λｓが小さいが、飽和磁束密度Ｂｓが小さく優れた磁気特性を示す圧粉磁心が得られ難い。一方、２〜４重量％のＳｉを含むＦｅ−Ｓｉ系合金粉末は、５〜８重量％のＳｉを含むＦｅ−Ｓｉ系合金粉末に比べて、優れた磁気特性を示す圧粉磁心が得られ易いが、軟磁性粉末単体の飽和磁歪λｓが大きいため、これらの粉末から構成される圧粉磁心においては磁化させたときの体積変形率が大きくなる。５〜８重量％のＳｉを含むＦｅ−Ｓｉ系合金粉末と、純Fe粉末の混合粉末を用いることで、磁化した時の体積変形率が小さく、高い機械的強度が得られることを見出した。５〜８重量％のＳｉを含むＦｅ−Ｓｉ系合金粉末と純Ｆｅ粉末の他、粉末間に均一に存在するように既存の無機絶縁バインダー層を作ることが好ましい。
In the present invention, attention is paid to the volume deformation rate when the dust core is magnetized. The volume deformation rate when magnetized means that the magnetic path direction length of the green compact when not magnetized is L0, and the magnetic path direction length of the green compact when magnetized is L1. It is a value represented by (L1-L0) / L0.
When the dust core is magnetized, an attractive force acts in the magnetic path direction, and the volume of the dust core is deformed by this attractive force. When this volume deformation rate is large, this change propagates to the air, resulting in high noise. Conversely, when the volume deformation rate is small, the noise is low. As a result of investigating the correlation between the volume deformation rate and the mechanical properties of the powder magnetic core composed of one kind of powder, the volume deformation rate is determined by the hardness and strength of the powder magnetic core and the particle diameter of the powder magnetic core. It was found that this relationship is small and largely depends mainly on the Young's modulus of the dust core and the saturation magnetostriction λs of the soft magnetic powder alone. The volume deformation rate decreases as the Young's modulus increases and the saturation magnetostriction λs of the soft magnetic powder alone decreases. However, Fe-Si alloy powder containing 5 to 8% by weight of Si has a small saturation magnetostriction λs of the soft magnetic powder alone, but has a small saturation magnetic flux density Bs and provides a dust core exhibiting excellent magnetic properties. hard. On the other hand, a Fe-Si alloy powder containing 2 to 4 wt% Si can provide a dust core exhibiting superior magnetic properties as compared to an Fe-Si alloy powder containing 5 to 8 wt% Si. However, since the saturation magnetostriction λs of the soft magnetic powder itself is large, the volumetric deformation rate when magnetized is increased in the dust core composed of these powders. It has been found that by using a mixed powder of Fe—Si based alloy powder containing 5 to 8 wt% Si and pure Fe powder, the volume deformation rate when magnetized is small and high mechanical strength can be obtained. In addition to the Fe—Si alloy powder containing 5 to 8 wt% of Si and pure Fe powder, it is preferable to make an existing inorganic insulating binder layer so as to exist uniformly between the powders.
磁性粉末占積率を８５％以上にすると、純Ｆｅ粉末が圧粉磁心の体積変形率に及ぼす影響を、Ｆｅ−Ｓｉ系合金粉末が緩和する。そのため、純Ｆｅ粉末の混合した量が減少するに伴い、圧粉磁心が磁気飽和したときの体積変形率は低減する。そして、純Ｆｅ粉末の全体に対する比率が５５％以下の場合、２〜４重量％のＳｉを含むＦｅ−Ｓｉ系合金粉末のみで構成される圧粉磁心と比べ、同程度の磁気特性でありながら、体積変形率が３ｐｐｍ以下と小さいものを得ることができる。特に、純Ｆｅ粉末の全体に対する比率が４０％以下の場合、２ｐｐｍ以下という更に小さい体積変形率を示す。 When the magnetic powder space factor is 85% or more, the effect of pure Fe powder on the volume deformation rate of the dust core is mitigated by the Fe-Si alloy powder. Therefore, as the amount of pure Fe powder mixed decreases, the volume deformation rate when the dust core is magnetically saturated decreases. And when the ratio with respect to the whole of pure Fe powder is 55% or less, it is a magnetic characteristic comparable as compared with the dust core comprised only by the Fe-Si type-alloy powder containing 2 to 4 weight% Si. A volume deformation rate as small as 3 ppm or less can be obtained. In particular, when the ratio of pure Fe powder to the whole is 40% or less, a smaller volume deformation rate of 2 ppm or less is exhibited.
圧粉磁心を構成する軟磁性粉末において、Ｆｅ−Ｓｉ系合金粉末の形状を図６(a)に示すように球形にし、９９．５質量％超がＦｅの純Ｆｅ粉末の形状を図６(ｂ)に示すように不規則にすると、Ｆｅ−Ｓｉ系合金粉末は純Ｆｅ粉末に比べて塑性変形し難い。そのため、これらの混合粉末を圧縮成形した場合、Ｆｅ−Ｓｉ系合金粉末は大きく塑性変形せずに純Ｆｅ粉末間に移動し、形状が不規則の純Ｆｅ粉末表面の突起した部分より大きな応力を受ける。これにより、純Fe粉末の全体に対する比率が増加するに伴い、圧環強度に換算した機械的強度は増加する。そして、純Ｆｅ粉末の全体に対する比率が１０％以上の場合、２〜４重量％のＳｉを含むＦｅ−Ｓｉ系合金粉末のみで構成される圧粉磁心と比べ、同程度の磁気特性でありながら、３０ＭＰa以上という十分高い強度をもつ圧粉磁心が得られる。特に、純Fe粉末の全体に対する比率が２０％以上の場合、４０ＭＰa以上という更に高い強度を示す。 In the soft magnetic powder composing the dust core, the shape of the Fe—Si based alloy powder is made spherical as shown in FIG. 6 (a), and the shape of pure Fe powder with more than 99.5 mass% Fe is shown in FIG. If it is irregular as shown in b), the Fe—Si based alloy powder is less likely to be plastically deformed than pure Fe powder. Therefore, when these mixed powders are compression-molded, the Fe-Si alloy powder moves between pure Fe powders without undergoing large plastic deformation, and exerts a larger stress than the protruding portion of the irregular pure Fe powder surface. receive. Thereby, as the ratio of the pure Fe powder to the whole increases, the mechanical strength converted to the crushing strength increases. And when the ratio with respect to the whole of pure Fe powder is 10% or more, it has the same magnetic characteristics as the dust core composed only of Fe-Si based alloy powder containing 2 to 4% by weight of Si. A powder magnetic core having a sufficiently high strength of 30 MPa or more can be obtained. In particular, when the ratio of the pure Fe powder to the whole is 20% or more, a higher strength of 40 MPa or more is exhibited.
また、混合粉末において、Ｆｅ−Ｓｉ系合金粉末の平均粒径を６０〜１００μｍとし、純Ｆｅ粉末の平均粒径を１０〜５０μｍにすることが好ましい。Ｆｅ−Ｓｉ系合金粉末1個が、純Fe粉末表面の突起部分と絶縁層を介して接触する領域が多くなるので、Ｆｅ−Ｓｉ系合金粉末が純Ｆｅ粉末から受ける応力が大きくなるからである。また、同様の理由により混合粉末の磁性粉末占積率を９０％以上にすることが好ましい。 In the mixed powder, it is preferable that the average particle diameter of the Fe—Si based alloy powder is 60 to 100 μm and the average particle diameter of the pure Fe powder is 10 to 50 μm. This is because the Fe-Si based alloy powder has a larger area in contact with the protrusions on the surface of the pure Fe powder via the insulating layer, so that the stress that the Fe-Si based alloy powder receives from the pure Fe powder increases. . For the same reason, it is preferable that the mixed powder has a magnetic powder space factor of 90% or more.
圧粉磁心の磁化を飽和させたときの体積変形率を減少させる方法としては、軟磁性粉末間のコーティング剤としてアルミナ、シリカ、マグネシア、カオリン等のセラミックス系バインダー及び絶縁材料を用い、これらを多量に配合させることがある。また、圧粉磁心の磁化を飽和させたときの体積変形率を減少させるには、本発明の圧粉磁心にエポキシ樹脂、アクリル樹脂、フェノール樹脂、シリコン樹脂、ポリアミド樹脂などの有機系の溶液、または水ガラス、コロイダルシリカ、コロイダルアルミナなどの無機系の溶液を含浸させ、その後硬化させることも有効である。 As a method of reducing the volume deformation rate when the magnetization of the powder magnetic core is saturated, ceramic binders and insulating materials such as alumina, silica, magnesia, kaolin, etc. are used as a coating agent between soft magnetic powders. May be blended in. Further, in order to reduce the volume deformation rate when the magnetization of the powder magnetic core is saturated, an organic solution such as an epoxy resin, an acrylic resin, a phenol resin, a silicon resin, or a polyamide resin is added to the powder magnetic core of the present invention, Alternatively, it is also effective to impregnate an inorganic solution such as water glass, colloidal silica, colloidal alumina, and then cure.
本発明の圧粉磁心は、圧粉体同士の間に設けられたセラミックス板により構成されることにより、磁化させたときの圧粉磁心同士の吸引力によるセラミックス板の縮む量が小さくなるので、騒音を抑制することができる。セラミックス板は、密度が高い程ヤング率が高くなるので、密度が９０％以上、さらには９５％以上であることがより好ましい。 Since the powder magnetic core of the present invention is composed of a ceramic plate provided between the powder compacts, the amount of shrinkage of the ceramic plate due to the attractive force between the powder magnetic cores when magnetized is reduced. Noise can be suppressed. Since the ceramic plate has a higher Young's modulus as the density is higher, the density is more preferably 90% or more, and more preferably 95% or more.
本発明の圧粉磁心にコイルを設けたリアクトルは動作時の磁心振動が小さくなるので、騒音を十分に抑制した従来にない高性能のリアクトルを得ることが出来る。また、ここで用いる圧粉磁心は高機械的強度を示すので、リアクトルを長時間駆動させても特性は劣化し難い。フリンジング磁束が外部回路に影響を与えないように、比透磁率μｒを調整するための非磁性ギャップとして用いたセラミックス板の周囲をコイルで覆う形状に設計することが好ましい。 Since the reactor provided with a coil in the dust core of the present invention has a reduced magnetic core vibration during operation, it is possible to obtain an unprecedented high performance reactor with sufficiently suppressed noise. In addition, since the dust core used here exhibits high mechanical strength, the characteristics hardly deteriorate even if the reactor is driven for a long time. In order to prevent the fringing magnetic flux from affecting the external circuit, it is preferable to design a shape in which the periphery of the ceramic plate used as a nonmagnetic gap for adjusting the relative permeability μr is covered with a coil.
本発明を実施例によって具体的に説明するが、これら実施例により本発明が限定されるものではない。
（実施例１）
表１に示すNo.１〜４の各合金組成の軟磁性粉末を用意した。各軟磁性粉末には、カオリン１質量％、アモルファスシリカ１．５質量％、アクリルエマルジョン１．５質量％、ステアリン酸亜鉛０．４質量％を添加している。この中から、Ｎｏ．１の９９．９％がＦｅの純Ｆｅ粉末と、Ｎｏ．４のＦｅ−６．５質量％Ｓｉ粉末を５４：４６の重量比率で混合し、Ｓｉ量が全体で約３質量％の軟磁性粉末を作成した。この軟磁性粉末を、成形圧２０ｔｏｎ／ｃｍ２で成形した後、窒素中雰囲気で、保持温度５００℃の熱処理を施し、本発明の圧粉磁心用の圧粉体を製造した。各磁気特性、圧環強度、抵抗率を測定した結果を表１に示す。
また、比較として、Ｎｏ．１〜４の各軟磁性粉末のみからならなる圧粉体と、No.1の純Ｆｅ粉末とＮｏ．４のＦｅ−６．５質量％Ｓｉ粉末を２：１の重量比率で混合（Ｓｉ量が全体で約１質量％）した圧粉体、Ｎｏ．２のＦｅ−１質量％Ｓｉ粉末とＮｏ．４のＦｅ−６．５質量％Ｓｉ粉末を６３：３７の重量比率で混合（Ｓｉ量が全体で約３質量％）した圧粉体を製造した。図１、図２に、全体のＳｉ含有量と、占積率、圧環強度との関係を記す。Ｓｉ量の異なる各軟磁性粉末を圧粉体にしたものより、純Ｆｅ粉末と、Ｓｉを含有するＦｅ−Ｓｉ系軟磁性粉末を混合した原料を用いた圧粉体の方が、占積率、圧環強度とも高い値を示す。
EXAMPLES The present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.
(Example 1)
Soft magnetic powders of No. 1 to No. 4 alloy compositions shown in Table 1 were prepared. To each soft magnetic powder, kaolin 1% by mass, amorphous silica 1.5% by mass, acrylic emulsion 1.5% by mass, and zinc stearate 0.4% by mass are added. From these, No. No. 1 99.9% Fe pure Fe powder, 4 Fe-6.5 mass% Si powder was mixed in a weight ratio of 54:46 to produce a soft magnetic powder having a total Si amount of about 3 mass%. The soft magnetic powder was molded at a molding pressure of 20 ton / cm 2 and then subjected to a heat treatment at a holding temperature of 500 ° C. in an atmosphere in nitrogen to produce a green compact for the dust core of the present invention. Table 1 shows the results of measuring each magnetic characteristic, crushing strength, and resistivity.
For comparison, no. 1 to 4 soft magnetic powders, No. 1 pure Fe powder, and No. 1 soft magnetic powder. No. 4 Fe-6.5 mass% Si powder mixed at a weight ratio of 2: 1 (Si content is about 1 mass% in total), No. 4 No. 2 Fe-1 mass% Si powder and No. 2 4 Fe-6.5 mass% Si powder was mixed at a weight ratio of 63:37 (Si content was about 3 mass% in total) to produce a green compact. 1 and 2 show the relationship between the total Si content, the space factor, and the crushing strength. The compaction ratio of the green compact using a raw material that is a mixture of pure Fe powder and Fe-Si soft magnetic powder containing Si is better than the compact of each soft magnetic powder with different Si content. The crushing strength shows a high value.
（実施例２）
表１に示すＮｏ．１の９９．９％がＦｅの純Ｆｅ粉末と、Ｎｏ．４のＦｅ６．５質量％Ｓｉ粉末を用い、混合する比率を変えて原料となる軟磁性粉末を準備した。この軟磁性粉末を、成形圧２０ｔｏｎ／ｃｍ２で成形した後、窒素中雰囲気で、保持温度５００℃の熱処理を施し、本発明の圧粉磁心用の圧粉体を製造した。各圧粉体の占積率と圧環強度を測定した結果を図３、図４に示す。
純Ｆｅ粉末の混合比率が大きくなるほど占積率、圧環強度とも高い値を示す。但し、コアロスは混合比率が大きくなるほど低下する傾向にあり、圧粉磁心として使用に耐える上限は、純Ｆｅ粉末の混合比率が５５％までである。
(Example 2)
No. shown in Table 1. No. 1 99.9% Fe pure Fe powder, 4 Fe6.5 mass% Si powder was used, and the mixing ratio was changed to prepare soft magnetic powder as a raw material. The soft magnetic powder was molded at a molding pressure of 20 ton / cm 2 , and then subjected to a heat treatment at a holding temperature of 500 ° C. in an atmosphere in nitrogen to produce a green compact for a dust core of the present invention. 3 and 4 show the results of measuring the space factor and the crushing strength of each green compact.
The larger the mixing ratio of the pure Fe powder, the higher the space factor and the crushing strength. However, the core loss tends to decrease as the mixing ratio increases, and the upper limit for use as a dust core is 55% for the mixing ratio of pure Fe powder.
（実施例３）
本発明の圧粉磁心をリアクトル用磁心に用いた一形態を図７に示す。本発明のリアクトルの圧粉磁心は、長円形状であり、長径が１３０ｍｍ、短径が６０ｍｍ、高さ３２ｍｍで平均磁路長が２８０ｍｍの寸法に形成した。半円環状の圧粉体１，２は、径方向の厚みを２０．５ｍｍに形成した。また、ブロック状の圧粉体３〜１２は、径方向の厚みが２０．５ｍｍで、磁路方向の長さが１１ｍｍになるよう形成した。半円環状の圧粉体１，２及びブロック状の圧粉体３〜１２の間には磁気的なギャップ１３〜２４を形成した。このギャップには密度が９９％のアルミナセラミック板を入れ、ギャップ幅（板厚）は全て０．９ｍｍとした。圧粉体１、２，３〜１２は、平均粒径が８０μｍのＦｅ−６．５％Ｓｉ系合金粉末と平均粒径が４０μｍの純Ｆｅ粉末が重量比で５：５で均一に混合した粉末に、カオリン１重量部、アモルファスシリカ１．５重量部、アクリルエマルジョン１．５重量部、ステアリン酸亜鉛０．４重量部を添加したものを用い、常温にて成形圧力２０００ＭＰａで圧縮成形し、その後成形体に窒素雰囲気中で温度１０７３Ｋの熱処理を施すことにより得た。そして、熱処理後にエポキシ系樹脂を真空含浸した。ここで得られた圧粉体の磁性粉末占積率は９１％である。
このブロック状の圧粉体３〜１２からなるストレート部に、コイル（図示せず）を設けた。コイルは幅６ｍｍ、厚さ１．６ｍｍの平角銅線を７６回巻き、かつ全てのギャップを覆うようにして備え付けた。これにより、本発明の圧粉磁心を用いたリアクトルを得ることができた。
このリアクトルは、周波数１０ｋＨｚ、信号電圧０．５Ｖ、直流重畳電流１５０Ａの時にインダクタンスが２００μH以上であり、直流重畳電流３００Ａの時にインダクタンスが６０μH以上あることが確認された。このリアクトルを図８に示す駆動周波数１０ｋＨｚのブースト型DC−DCコンバータのＬ１として搭載し、直流重畳電流８０Ａ、周波数１０ｋＨｚにおいて実効値１１．５Ａのリップル電流を流した。このとき、圧粉磁心に印加している直流バイアス磁界は２２０００Ａ／ｍで、周波数１０ｋＨｚの交流磁界中における圧粉磁心の磁化の最大変化量は０．２４Ｔである。そして、この条件でのリアクトル動作時に、磁心表面から１０ｃｍの距離で測定した騒音と、この圧粉磁心の磁化が飽和した時の体積変形量、そして、この圧粉磁心の圧環強度に換算した機械的強度を表２に示す。圧粉磁心の体積変形量が２．５ｐｐｍにおける騒音は７５ｄＢであり、非常に騒音の少ないリアクトルを得ることができた。
また、図５に、上記と同様にして測定した場合の、純Ｆｅ粉末の混合比率と体積変形率の関係を示す。
(Example 3)
FIG. 7 shows an embodiment in which the dust core of the present invention is used as a reactor core. The dust core of the reactor of the present invention has an oval shape, and has a major axis of 130 mm, a minor axis of 60 mm, a height of 32 mm, and an average magnetic path length of 280 mm. The semicircular green compacts 1 and 2 were formed to have a radial thickness of 20.5 mm. The block-shaped green compacts 3 to 12 were formed so that the radial thickness was 20.5 mm and the length in the magnetic path direction was 11 mm. Magnetic gaps 13 to 24 were formed between the semi-circular green compacts 1 and 2 and the block-shaped green compacts 3 to 12. An alumina ceramic plate having a density of 99% was put in this gap, and the gap width (plate thickness) was all 0.9 mm. In the green compacts 1, 2, 3 to 12, Fe-6.5% Si alloy powder having an average particle diameter of 80 μm and pure Fe powder having an average particle diameter of 40 μm were uniformly mixed at a weight ratio of 5: 5. Using powder added with 1 part by weight of kaolin, 1.5 parts by weight of amorphous silica, 1.5 parts by weight of acrylic emulsion, and 0.4 parts by weight of zinc stearate, compression molding is performed at room temperature with a molding pressure of 2000 MPa, Thereafter, the molded body was obtained by performing a heat treatment at a temperature of 1073 K in a nitrogen atmosphere. Then, the epoxy resin was vacuum impregnated after the heat treatment. The magnetic powder space factor of the green compact obtained here is 91%.
A coil (not shown) was provided on the straight portion made of these block-shaped green compacts 3-12. The coil was provided so that a flat copper wire having a width of 6 mm and a thickness of 1.6 mm was wound 76 times and all the gaps were covered. Thereby, the reactor using the dust core of this invention was able to be obtained.
It was confirmed that this reactor had an inductance of 200 μH or more when the frequency was 10 kHz, the signal voltage was 0.5 V, and the DC superimposed current was 150 A, and the inductance was 60 μH or more when the DC superimposed current was 300 A. This reactor was mounted as L1 of a boost type DC-DC converter having a drive frequency of 10 kHz shown in FIG. 8, and a ripple current having an effective value of 11.5 A was passed at a DC superimposed current of 80 A and a frequency of 10 kHz. At this time, the DC bias magnetic field applied to the dust core is 22000 A / m, and the maximum change in magnetization of the dust core in an AC magnetic field with a frequency of 10 kHz is 0.24 T. Then, during the reactor operation under these conditions, the noise measured at a distance of 10 cm from the surface of the magnetic core, the volume deformation when the magnetization of the dust core is saturated, and the machine converted to the crushing strength of the dust core Table 2 shows the mechanical strength. When the volume deformation of the dust core was 2.5 ppm, the noise was 75 dB, and a reactor with very little noise could be obtained.
FIG. 5 shows the relationship between the mixing ratio of pure Fe powder and the volume deformation rate when measured in the same manner as described above.
（比較例）
図７に示すような、長円形状の圧粉磁心を製造した。長径、短径、高さ、平均磁路長とも実施例１と同じ寸法である。また、半円環状及びブロック状圧粉体の寸法、およびそれらの間に形成するギャップの幅は実施例１と同様である。ここで用いた圧粉体には平均粒径が４０μｍのＦｅ−３％Ｓｉ系合金粉末にカオリン１重量部、アモルファスシリカ１．５重量部、アクリルエマルジョン１．５重量部、ステアリン酸亜鉛０．４重量部を添加した粉末を用いた。この粉末を常温にて成形圧力２０００ＭＰａで圧縮成形し、その後成形体に窒素雰囲気中で温度１０７３Ｋの熱処理を施した。そして、熱処理後にエポキシ系樹脂を真空含浸した。ここで得られた圧粉体の磁性粉末占積率は８９％である。この圧粉体の磁化が飽和したときの体積変形率は、表２に示すように４．５ｐｐｍで、圧環強度に換算した機械的強度は３７ＭＰaである。この圧粉磁心に実施例１と同様にコイルを設け、リアクトルとした。
このリアクトルは、周波数１０ｋＨｚ、信号電圧０．５Ｖ、直流重畳電流１５０Ａの時にインダクタンスが２００μH以上であり、直流重畳電流３００Ａの時にインダクタンスが６０μH以上あることが確認された。このリアクトルを図８に示す駆動周波数１０ｋＨｚのブースト型DC−DCコンバータのＬ１として搭載し、直流重畳電流８０Ａ、周波数１０ｋＨｚにおいて実効値１１．５Ａのリップル電流を流した。このとき、圧粉磁心に印加している直流バイアス磁界は２２０００Ａ／ｍで、周波数１０ｋＨｚの交流磁界中における圧粉磁心の磁化の最大変化量は０．２４Ｔである。そして、この条件でのリアクトル動作時に、磁心表面から１０ｃｍの距離で測定した騒音を調べた。表２に示したように、圧粉磁心の磁化が飽和したときの体積変形率が４．５ｐｐｍにおける騒音は８５ｄＢであり、磁化が飽和したときの体積変形率が高い圧粉磁心を用いたリアクトルでは、騒音が大きくなることが解った。
(Comparative example)
An ellipsoidal powder magnetic core as shown in FIG. 7 was produced. The major axis, minor axis, height, and average magnetic path length are the same dimensions as in Example 1. The dimensions of the semi-annular and block compacts and the width of the gap formed between them are the same as in the first embodiment. The green compact used here is an Fe-3% Si alloy powder having an average particle size of 40 μm, 1 part by weight of kaolin, 1.5 parts by weight of amorphous silica, 1.5 parts by weight of an acrylic emulsion, and 0.5 mg of zinc stearate. A powder added with 4 parts by weight was used. This powder was compression-molded at a molding pressure of 2000 MPa at room temperature, and then the molded body was heat-treated at a temperature of 1073 K in a nitrogen atmosphere. Then, the epoxy resin was vacuum impregnated after the heat treatment. The green compact thus obtained has a magnetic powder space factor of 89%. When the magnetization of the green compact is saturated, the volume deformation rate is 4.5 ppm as shown in Table 2, and the mechanical strength converted to the crushing strength is 37 MPa. The dust core was provided with a coil in the same manner as in Example 1 to form a reactor.
It was confirmed that this reactor had an inductance of 200 μH or more when the frequency was 10 kHz, a signal voltage of 0.5 V, and a DC superimposed current of 150 A, and an inductance of 60 μH or more when the DC superimposed current was 300 A. This reactor was mounted as L1 of a boost type DC-DC converter having a drive frequency of 10 kHz shown in FIG. 8, and a ripple current having an effective value of 11.5 A was passed at a DC superimposed current of 80 A and a frequency of 10 kHz. At this time, the DC bias magnetic field applied to the dust core is 22000 A / m, and the maximum change in magnetization of the dust core in an AC magnetic field with a frequency of 10 kHz is 0.24 T. The noise measured at a distance of 10 cm from the surface of the magnetic core during the reactor operation under these conditions was examined. As shown in Table 2, the noise at a volume deformation rate of 4.5 ppm when the magnetization of the dust core is saturated is 85 dB, and a reactor using a dust core having a high volume deformation rate when the magnetization is saturated Then, it turned out that noise becomes loud.
１、２、３〜１２：圧粉体、
１３〜２４：ギャップ（セラミックス板配置スペース）、
Ｌ１ リアクトル、
Ｑ１ トランジスタ、
Ｄ１ ダイオード、
Ｃ１，Ｃ２ キャパシタ
1, 2, 3-12: green compact,
13-24: Gap (ceramics plate placement space),
L1 reactor,
Q1 transistor,
D1 diode,
C1, C2 capacitors
Claims (7)
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| JP2009252961A (en) * | 2008-04-04 | 2009-10-29 | Kobe Steel Ltd | Soft magnetic material for dust core and dust core |
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| US9773597B2 (en) | 2011-02-22 | 2017-09-26 | Mitsubishi Materials Corporation | Composite soft magnetic material having low magnetic strain and high magnetic flux density, method for producing same, and electromagnetic circuit component |
| JPWO2014068928A1 (en) * | 2012-10-31 | 2016-09-08 | パナソニックＩｐマネジメント株式会社 | Composite magnetic body and method for producing the same |
| WO2014068928A1 (en) * | 2012-10-31 | 2014-05-08 | パナソニック株式会社 | Composite magnetic body and method for manufacturing same |
| US9881722B2 (en) | 2012-10-31 | 2018-01-30 | Panasonic Intellectual Property Management Co., Ltd. | Composite magnetic body and method for manufacturing same |
| KR20140142174A (en) | 2013-06-03 | 2014-12-11 | 가부시키가이샤 다무라 세이사쿠쇼 | Soft magnetic powder, core, low noise reactor and method for manufacturing core |
| JP2016012630A (en) * | 2014-06-27 | 2016-01-21 | 日立金属株式会社 | Powder-compact magnetic core |
| JP2016171167A (en) * | 2015-03-12 | 2016-09-23 | 日立化成株式会社 | Magnetic sheet material arranged by use of powder compact, and method for manufacturing the same |
| CN105161245A (en) * | 2015-08-07 | 2015-12-16 | 广州有色金属研究院 | Multi-scale structure composite magnetic powder core and preparation method thereof |
| JP2017054910A (en) * | 2015-09-09 | 2017-03-16 | Tdk株式会社 | Soft magnetic metal powder compact core |
| KR20170141605A (en) * | 2016-06-15 | 2017-12-26 | 티디케이가부시기가이샤 | Soft magnetic metal powder, soft magnetic metal fired body, and coil type electronic device |
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