JP3970401B2 - Current detector - Google Patents

Current detector Download PDF

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Publication number
JP3970401B2
JP3970401B2 JP00320998A JP320998A JP3970401B2 JP 3970401 B2 JP3970401 B2 JP 3970401B2 JP 00320998 A JP00320998 A JP 00320998A JP 320998 A JP320998 A JP 320998A JP 3970401 B2 JP3970401 B2 JP 3970401B2
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Japan
Prior art keywords
coil
bobbin
current detector
primary coil
current
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JP00320998A
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Japanese (ja)
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JPH11201999A (en
Inventor
実 野田
洋昭 鈴木
隆 安藤
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Tokin Corp
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NEC Tokin Corp
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Priority to JP00320998A priority Critical patent/JP3970401B2/en
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Description

【0001】
【発明の属する技術分野】
本発明は各種産業機器,動力機器,電化製品,電子機器などみ使用される電流検出器に関するものである。
【0002】
【従来の技術】
NC工作機械,ロボット等の産業機器,エアコン等の電化製品には動力源としてDCモータや同期モータ,誘導モータ等のACモータが広く使用されている。これらのモータは,サーボ及びインバータによって制御されており,高精度,高速制御にはモータに流れる直流電流を検出する直流電流検出器が必要不可欠である。これらの電流検出器は,被測定電流の1次側と被測定電流に比例した出力を発生する2次側回路部が電気的に絶縁されていなければならないため,電流検出の方式としては3つの方式がある。
【0003】
ひとつは,被測定電流をシャント抵抗に流し,その両端電圧を絶縁して検出する絶縁アンプ方式。
【0004】
二つ目は,磁気ギャップを有したコアに,コイルを巻き,被測定電流を磁気ギャップに生じる磁束をホールセンサで電圧信号に変換し,アンプ回路で増幅することで検出する磁気比例式ホールCT方式。
【0005】
三つ目は,二つ目の磁気比例式ホールCTと同様に,磁気ギャップつきのコアとホールセンサを用いるが,1次コイルの被測定電流によって生じる磁束を2次コイル(電流検出用コイル)に電流を流して打ち消すように,ホールセンサを含む制御ループが動作するものである。磁気ギャップ内の磁束が常に0になるので,1次コイルの電流に比例して流れる2次電流を測定することで被測定電流を検出する磁気平衡式ホールCTがある。
【0006】
各方式には,次のような特長がある。▲1▼絶縁アンプ方式は,高精度であるが高価格であること。▲2▼磁気比例式ホールCTでは,ホールセンサで得られる電圧は,小さいので必要電圧までアンプ増幅するためゲインによって出力の温度ドリフト,自己発熱によるドリフト等の誤差が大きい。但し,3方式の中では最も安価である。▲3▼磁気平衡式ホールCTは,前記誤差が小さく高精度であるが,磁気比例式ホールCTより高価格である。
【0007】
近年,サーボドライバ,インバータドライバの小型化及び高精度,高機能化がめざましくそれらに使用する電流検出器にも小型で高精度が要求されるため,前記3方式の中でも特に磁気平衡式ホールCTの需要が高まっている。
【0008】
又モータ容量別による需要では20kW以下の低い電流の方が断然多いため,被測定電流の測定端子及び入出力信号端子を基板に直接半田付けするオンボードタイプの電流検出器が望まれている。
【0009】
図5は従来の磁気平衡式ホールCTの構造を示す斜視図である。図5に示すように,従来この種のホールCTは,打ち抜き成形した金属磁性板を積層してコア51を形成し,ボビン53に巻いた2次コイル54をコア51の一辺に配設し,被測定電流を流す1次コイル56は,導線をコアの内径に1ターン貫通させるか又は,筐体ケースの上から巻き回すことで形成している。
【0010】
【発明が解決しようとする課題】
しかしながら,上記ホールCTにおいて,1次コイル56によって生じる磁束Φ1とこれを打ち消すように,2次コイル54に流れる電流によって生じる磁束Φ2の和が磁気ギャップ57内で0になるためには,このように1次コイル56と2次コイル54及び磁気ギャップ57を離れて形成した場合,測定電流の範囲内で一次コイル56による磁束でコアが磁気飽和しないように,コアの断面積を大きくする必要がある。そのため金属磁性板の積層枚数が増え価格的に高価になっている。また,このようなCTは,1次コイル56が1ターン貫通で測定電流が高くなる。太い導線を貫通させるためコア51内径は大きくなり小型にしにくい問題や1次巻き線はハーネス以外では,出来ない問題がある。
【0011】
そこで,本発明の一技術的課題は,低い電流範囲の検出が可能で,小型で,安価な磁気平衡式のホールCTからなる電流検出器を提供することにある。
【0012】
また,本発明の他の技術的課題は,1次コイルが内蔵され,被測定電流の測定端子と入出力端子が基板に直接半田づけ出来るオンボードタイプである電流検出器を提供することにある。
【0013】
【課題を解決するための手段】
前記技術的課題を解決するために,本発明の電流検出器では,コイルを巻き回したボビンと,磁気ギャップを有する強磁性体からなるコアと,感磁素子を実装した回路基板とを備えた電流検出器において,前記ボビン上に前記コイルとして、1次コイルと2次コイルとを形成した磁気平衡式であり、前記ボビンは,前記1次コイルと前記2次コイルとを絶縁分割するための隔壁を有し、前記1次コイルと前記2次コイルとを前記隔壁を介して隣接させて設け、前記強磁性体からなるコアは,前記磁気ギャップを前記ボビンのつばの高さより小さくするように形成した回周形状を備える一体物から実質的になることを特徴としている。
【0015】
また,本発明では,コイルを巻き回したボビンと,磁気ギャップを有する強磁性体からなるコアと,感磁素子を実装した回路基板とを備えた電流検出器において,前記ボビン上に前記コイルとして1次コイルと2次コイルとを形成した磁気平衡式であり、前記2次コイルの上に前記1次コイルが巻回され、前記2次コイルの上に絶縁層を設け,前記絶縁層の上に前記1次コイルが巻回され、前記強磁性体からなるコアは,前記磁気ギャップを前記ボビンのつばの高さより小さくするように形成した回周形状を備える一体物から実質的になることを特徴としている。
【0017】
また,本発明では,前記いずれか一つの電流検出器において,前記1次コイル又は前記2次コイルの内のいずれか一方が3層絶縁ワイヤーからなることを特徴としている。
【0019】
【発明の実施の形態】
次に,本発明の実施の形態について図面を参照して説明する。
【0020】
図1乃至図3は本発明の一実施の形態による電流検出器を示し,図1は上面断面図,図2は正面図,及び図3はボビン挿入前後のコアの状態を示す説明図である。図1に示すように,電流検出器は,絶縁性樹脂からなる筒状のボビン1には,被測定電流を流す1次コイル11と1次コイル11の磁界を打ち消すための2次コイル12を隔壁13を介して隣接させて設けている。
【0021】
図3に示すように,金属磁性板からなる強磁性体からなるコア2は,予め磁気ギャップ4をボビン1の鍔14が通せる程に開放されて成形しており,ボビン1を挿入後に,コア2の外側部2aを折り曲げて,所定の磁気ギャップ寸法Lgまで狭め,成形してU字状のコア2を形成する。
【0022】
図2に示すように,ホールセンサ3及び他回路部品を実装し,入出力端子7を備えた回路基板5は,ホールセンサ3は,磁気ギャップ4内に位置するように,ボビン1に設けられた2か所の収納係止部14a,14bによって固定保持される。2次コイル12の端末はボビン1に設けたピン8a,8bにからげられ,そのピンは,回路基板5と接続される。被測定電流は,1次コイルの端末11a,11bに通電する。
【0023】
図1のように,1次コイル11と2次コイル12及び磁気ギャップ4を隣接して配置する事で1次コイル11によって生じる磁束Φ1と2次コイル12に流れる電流によって生じる磁束Φ2はボビン1内の1次コイル11と2次コイル12との間で相殺されるためにコア2に漏れる磁束が小さくなり,コア2の断面積を小さくすることが出来る。そのためコア2は,金属磁性板の単板を折り曲げるだけで十分であり,小型で簡易な構成にする事が出来る。
【0024】
図4は本発明の他の実施の形態による電流検出器を示す断面図である。図4を参照すると,他の実施の形態による電流検出器は,ボビン23に2次コイル22を巻き回した上に絶縁テープ等からなる絶縁体24を形成しその上から1次コイル21を巻き回した構成である点で,前記の実施の形態による電流検出器とは異なる。前記の実施の形態における電流検出器と同様に1次及び2次コイル21,22間で磁束を相殺するため,同様の効果を得ることが出来る。又,本発明の上記実施の形態では,鍔13又は絶縁体24で1次コイル11又は21と2次コイル12又は22との絶縁を確保しているが,どちらか一方のコイルに3層絶縁ワイヤや絶縁皮膜電線等を用いて前記と同様にコイルを配設しても同様の効果を得ることができるのは当然である。
【0025】
【発明の効果】
以上説明したように,本発明によれば,低い電流範囲の検出が可能で,小型で,安価な磁気平衡式のホールCTからなる電流検出器を提供することができる。
【0026】
また,本発明によれば,1次コイルが内蔵され,被測定電流の測定端子と入出力端子が基板に直接半田づけ出来るオンボードタイプである電流検出器を提供することができる。
【図面の簡単な説明】
【図1】本発明の一実施の形態による電流検出器を示す上面断面図である。
【図2】図1の電流検出器の正面図である。
【図3】図1の電流検出器のボビン挿入前後のコアの状態説明図である。
【図4】本発明の他の実施の形態による電流検出器を示す上面断面図である。
【図5】従来技術による磁気平衡式ホールCTの構成図である。
【符号の説明】
1,53 ボビン
2,51 コア
3,52 ホールセンサ
5,55 回路基板
11,21,56 1次コイル
12,22,54 2次コイル
13 隔壁
14 鍔
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a current detector used only for various industrial equipment, power equipment, electrical appliances, electronic equipment and the like.
[0002]
[Prior art]
AC motors such as DC motors, synchronous motors, and induction motors are widely used as power sources in industrial machines such as NC machine tools, robots, and electrical appliances such as air conditioners. These motors are controlled by servos and inverters, and a DC current detector that detects the DC current flowing through the motor is indispensable for high-precision and high-speed control. These current detectors must be electrically insulated from the primary side of the current to be measured and the secondary circuit section that generates an output proportional to the current to be measured. There is a method.
[0003]
The first is an insulation amplifier method that detects the current to be measured by passing it through a shunt resistor and insulating the voltage across it.
[0004]
The second is a magnetic proportional Hall CT that is detected by winding a coil around a core with a magnetic gap, converting the magnetic current generated in the magnetic gap into a voltage signal with a Hall sensor, and amplifying it with an amplifier circuit. method.
[0005]
The third one uses a core with a magnetic gap and a Hall sensor, similar to the second magnetic proportional Hall CT. However, the magnetic flux generated by the measured current of the primary coil is transferred to the secondary coil (current detection coil). The control loop including the Hall sensor operates so as to cancel the current flow. Since the magnetic flux in the magnetic gap is always 0, there is a magnetically balanced Hall CT that detects the current to be measured by measuring the secondary current that flows in proportion to the current of the primary coil.
[0006]
Each method has the following features. (1) The insulation amplifier method is highly accurate but expensive. (2) In the magnetic proportional Hall CT, since the voltage obtained by the Hall sensor is small, the amplifier amplifies the voltage to the required voltage, so that errors such as temperature drift of output and drift due to self-heating are large due to gain. However, it is the cheapest of the three methods. {Circle around (3)} The magnetically balanced Hall CT is small and highly accurate, but is more expensive than the magnetic proportional Hall CT.
[0007]
In recent years, servo drivers and inverter drivers have become smaller and more accurate and more functional, and current detectors used for them are also required to be smaller and more accurate. Demand is increasing.
[0008]
On the other hand, a demand of 20 kW or less is more demanded by motor capacity, so an on-board type current detector that directly solders the measurement current measurement terminal and the input / output signal terminal to the board is desired.
[0009]
FIG. 5 is a perspective view showing the structure of a conventional magnetically balanced hall CT. As shown in FIG. 5, conventionally, this type of hole CT has a core 51 formed by stacking punched metal magnetic plates, and a secondary coil 54 wound around a bobbin 53 is disposed on one side of the core 51. The primary coil 56 for passing the current to be measured is formed by passing the conducting wire through the inner diameter of the core for one turn or by winding it from above the housing case.
[0010]
[Problems to be solved by the invention]
However, in the Hall CT, in order for the sum of the magnetic flux Φ1 generated by the primary coil 56 and the magnetic flux Φ2 generated by the current flowing in the secondary coil 54 to cancel out this, it becomes 0 in the magnetic gap 57. When the primary coil 56, the secondary coil 54, and the magnetic gap 57 are formed apart from each other, it is necessary to increase the cross-sectional area of the core so that the core is not magnetically saturated with the magnetic flux generated by the primary coil 56 within the measurement current range. is there. For this reason, the number of laminated metal magnetic plates is increased and the price is increased. Further, in such CT, the primary coil 56 passes through one turn and the measurement current increases. There is a problem that the inner diameter of the core 51 becomes large because a thick conductor is penetrated, and it is difficult to reduce the size, and there is a problem that the primary winding cannot be made other than a harness.
[0011]
Accordingly, an object of the present invention is to provide a current detector comprising a magnetically balanced Hall CT that can detect a low current range, is small, and is inexpensive.
[0012]
Another technical problem of the present invention is to provide an on-board type current detector having a built-in primary coil and capable of directly soldering a measurement current measurement terminal and an input / output terminal to a substrate. .
[0013]
[Means for Solving the Problems]
In order to solve the above technical problem, the current detector of the present invention includes a bobbin around which a coil is wound, a core made of a ferromagnetic material having a magnetic gap, and a circuit board on which a magnetosensitive element is mounted. In the current detector, a magnetic balance type in which a primary coil and a secondary coil are formed as the coil on the bobbin, and the bobbin is used for insulating and dividing the primary coil and the secondary coil. And having a partition, the primary coil and the secondary coil are provided adjacent to each other via the partition, and the core made of the ferromagnetic material is configured so that the magnetic gap is smaller than the height of the collar of the bobbin. It is characterized by substantially consisting of an integral body having a formed circular shape .
[0015]
In the present invention, in a current detector comprising a bobbin around which a coil is wound, a core made of a ferromagnetic material having a magnetic gap, and a circuit board on which a magnetosensitive element is mounted, the coil is placed on the bobbin as the coil. A magnetic balance type in which a primary coil and a secondary coil are formed, the primary coil is wound on the secondary coil, an insulating layer is provided on the secondary coil, The primary coil is wound around the core, and the core made of the ferromagnetic material is substantially composed of an integral body having a circular shape formed so that the magnetic gap is smaller than the height of the collar of the bobbin. It is a feature.
[0017]
In the present invention, in any one of the current detectors, either the primary coil or the secondary coil is made of a three-layer insulated wire.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0020]
1 to 3 show a current detector according to an embodiment of the present invention. FIG. 1 is a top sectional view, FIG. 2 is a front view, and FIG. 3 is an explanatory view showing a state of a core before and after a bobbin is inserted. . As shown in FIG. 1, the current detector has a cylindrical bobbin 1 made of an insulating resin provided with a primary coil 11 for passing a current to be measured and a secondary coil 12 for canceling the magnetic field of the primary coil 11. They are provided adjacent to each other via the partition wall 13.
[0021]
As shown in FIG. 3, the core 2 made of a ferromagnetic material made of a metal magnetic plate is formed in advance so that the magnetic gap 4 can be passed through the flange 14 of the bobbin 1, and after inserting the bobbin 1, The outer portion 2a of the core 2 is bent, narrowed to a predetermined magnetic gap dimension Lg, and molded to form a U-shaped core 2.
[0022]
As shown in FIG. 2, the Hall sensor 3 and other circuit components are mounted, and the circuit board 5 having the input / output terminals 7 is provided on the bobbin 1 so that the Hall sensor 3 is located in the magnetic gap 4. It is fixed and held by the two storage locking portions 14a and 14b. The end of the secondary coil 12 is tangled with pins 8 a and 8 b provided on the bobbin 1, and the pins are connected to the circuit board 5. The current to be measured is supplied to the terminals 11a and 11b of the primary coil.
[0023]
As shown in FIG. 1, by arranging the primary coil 11, the secondary coil 12, and the magnetic gap 4 adjacent to each other, the magnetic flux Φ1 generated by the primary coil 11 and the magnetic flux Φ2 generated by the current flowing through the secondary coil 12 are Since the primary coil 11 and the secondary coil 12 cancel each other, the magnetic flux leaking to the core 2 is reduced, and the cross-sectional area of the core 2 can be reduced. Therefore, it is sufficient for the core 2 to bend a single metal magnetic plate, and the core 2 can be made small and simple.
[0024]
FIG. 4 is a cross-sectional view showing a current detector according to another embodiment of the present invention. Referring to FIG. 4, in a current detector according to another embodiment, a secondary coil 22 is wound around a bobbin 23, an insulator 24 made of insulating tape or the like is formed, and the primary coil 21 is wound thereon. The current detector is different from the current detector according to the above-described embodiment in that the configuration is rotated. Since the magnetic flux is canceled between the primary and secondary coils 21 and 22 similarly to the current detector in the above-described embodiment, the same effect can be obtained. In the above embodiment of the present invention, the insulation between the primary coil 11 or 21 and the secondary coil 12 or 22 is ensured by the flange 13 or the insulator 24, but three-layer insulation is provided for either one of the coils. Naturally, the same effect can be obtained even if the coil is disposed in the same manner as described above using a wire, an insulating film electric wire or the like.
[0025]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a current detector including a magnetically balanced Hall CT that can detect a low current range, is small, and is inexpensive.
[0026]
Further, according to the present invention, it is possible to provide an on-board type current detector in which a primary coil is incorporated and a measurement terminal and an input / output terminal of a current to be measured can be directly soldered to a substrate.
[Brief description of the drawings]
FIG. 1 is a top sectional view showing a current detector according to an embodiment of the present invention.
FIG. 2 is a front view of the current detector of FIG.
3 is a state explanatory diagram of a core before and after insertion of a bobbin of the current detector of FIG. 1;
FIG. 4 is a top sectional view showing a current detector according to another embodiment of the present invention.
FIG. 5 is a configuration diagram of a magnetically balanced hall CT according to the prior art.
[Explanation of symbols]
1, 53 Bobbin 2, 51 Core 3, 52 Hall sensor 5, 55 Circuit board 11, 21, 56 Primary coil 12, 22, 54 Secondary coil 13 Bulkhead 14 鍔

Claims (3)

コイルを巻き回したボビンと,磁気ギャップを有する強磁性体からなるコアと,感磁素子を実装した回路基板とを備えた電流検出器において,前記ボビン上に前記コイルとして、1次コイルと2次コイルとを形成した磁気平衡式であり、前記ボビンは,前記1次コイルと前記2次コイルとを絶縁分割するための隔壁を有し、前記1次コイルと前記2次コイルとを前記隔壁を介して隣接させて設け、前記強磁性体からなるコアは,前記磁気ギャップを前記ボビンのつばの高さより小さくするように形成した回周形状を備える一体物から実質的になることを特徴とする電流検出器。In a current detector comprising a bobbin around which a coil is wound, a core made of a ferromagnetic material having a magnetic gap, and a circuit board on which a magnetosensitive element is mounted, a primary coil and 2 as the coil on the bobbin The bobbin has a partition for insulatingly dividing the primary coil and the secondary coil, and the primary coil and the secondary coil are connected to the partition wall. The core made of the ferromagnetic material is substantially made of an integral body having a circular shape formed so that the magnetic gap is smaller than the height of the flange of the bobbin. Current detector. コイルを巻き回したボビンと,磁気ギャップを有する強磁性体からなるコアと,感磁素子を実装した回路基板とを備えた電流検出器において,前記ボビン上に前記コイルとして1次コイルと2次コイルとを形成した磁気平衡式であり、前記2次コイルの上に前記1次コイルが巻回され、前記2次コイルの上に絶縁層を設け,前記絶縁層の上に前記1次コイルが巻回され、前記強磁性体からなるコアは,前記磁気ギャップを前記ボビンのつばの高さより小さくするように形成した回周形状を備える一体物から実質的になることを特徴とする電流検出器。 In a current detector including a bobbin around which a coil is wound, a core made of a ferromagnetic material having a magnetic gap, and a circuit board on which a magnetosensitive element is mounted, a primary coil and a secondary coil are provided as the coil on the bobbin. A magnetic balance type formed with a coil, wherein the primary coil is wound on the secondary coil, an insulating layer is provided on the secondary coil, and the primary coil is provided on the insulating layer. The current detector is characterized in that the wound and core made of the ferromagnetic material is substantially made of an integral body having a circular shape formed so that the magnetic gap is smaller than the height of the collar of the bobbin . . 請求項1又は2に記載の電流検出器において,前記1次コイル又は前記2次コイルの内のいずれか一方が3層絶縁ワイヤーからなることを特徴とする電流検出器。 3. The current detector according to claim 1, wherein either the primary coil or the secondary coil is made of a three-layer insulated wire.
JP00320998A 1998-01-09 1998-01-09 Current detector Expired - Lifetime JP3970401B2 (en)

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JP3970401B2 true JP3970401B2 (en) 2007-09-05

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JP2007285964A (en) * 2006-04-19 2007-11-01 Nec Tokin Corp Current detector
US9698647B2 (en) 2014-09-25 2017-07-04 Regal Beloit America, Inc. Electric machine with magnetic sensor

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