JPS6046386B2 - current detector - Google Patents

current detector

Info

Publication number
JPS6046386B2
JPS6046386B2 JP52033748A JP3374877A JPS6046386B2 JP S6046386 B2 JPS6046386 B2 JP S6046386B2 JP 52033748 A JP52033748 A JP 52033748A JP 3374877 A JP3374877 A JP 3374877A JP S6046386 B2 JPS6046386 B2 JP S6046386B2
Authority
JP
Japan
Prior art keywords
magnetic field
current
semiconductor magnetoresistive
under test
circuit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
JP52033748A
Other languages
Japanese (ja)
Other versions
JPS53118175A (en
Inventor
春男 鋪
丈雄 手塚
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NEC Corp
Original Assignee
Nippon Electric Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nippon Electric Co Ltd filed Critical Nippon Electric Co Ltd
Priority to JP52033748A priority Critical patent/JPS6046386B2/en
Publication of JPS53118175A publication Critical patent/JPS53118175A/en
Publication of JPS6046386B2 publication Critical patent/JPS6046386B2/en
Expired legal-status Critical Current

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Description

【発明の詳細な説明】 この発明は電流検出コイルの有する直流電位に関係な
く被測定回路の電流を電流検出コイルによつて検出する
ことが可能な直線性の良い電流検出器に関するものであ
る。
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a current detector with good linearity that allows a current detection coil to detect a current in a circuit under test regardless of the DC potential of the current detection coil.

従来電流検出器は被測定分流器の両端に加わる電位を
他方が地気に接続された二個の倍率器で均等に分割し、
差動増幅器で検出する方法があるが、被測定分流器の電
位が高い場合、感度を損う欠点があつた。
Conventional current detectors equally divide the potential applied to both ends of the shunt to be measured using two multipliers, one of which is connected to the ground.
There is a method of detection using a differential amplifier, but this method has the disadvantage of impairing sensitivity when the potential of the shunt to be measured is high.

そこでこの対策として磁気抵抗素子を活用する電流検出
器があるが、被測定回路の電流とセンサー出力電圧とが
比例しない欠点を有している。 第1図は従来の実施例
の回路図を示す。
As a countermeasure to this problem, there is a current detector that utilizes a magnetoresistive element, but it has the drawback that the current in the circuit under test is not proportional to the sensor output voltage. FIG. 1 shows a circuit diagram of a conventional embodiment.

ここで1、1’は被測定回路に接続される端子、2は端
子1、1’より流入した電流に比例した磁界を発生する
コイル、3、3’は半導体磁気抵抗素子、4、4’は抵
抗で、3、3’と4、4’とでブリッジ回路を構成する
。また6は入力インピーダンスの高い差動増幅器、7は
その出力、8はブリッジ回路と差動増幅器に直流電圧を
供給する端子てある。コイル2に電流が流れると、コイ
ル2の発生磁界は半導体磁気抵抗素子3’に加わつて、
その抵抗値が変り、ブリッジ出力a、a’間に電圧を発
生する。この電圧は差動増幅器6て増幅される。半導体
磁気抵抗素子3’において加わる磁界が零のときの抵抗
値をR。、磁界がBのときの抵抗値をRBとするとRB
/Roは第3図の素子の磁界と抵抗値の特性図のごとく
磁界均までは磁界に比例しない。それゆえ被測定回路よ
り流出する電流が小さい場合には半導体磁気抵抗素子に
加わる磁界が低く、ブリッジ出力電圧が被測定回路の電
流と比例しない。この事実は電流値の単なる変化を検出
するデジタル的なセンサーとして使用する場合にはあま
り問題とならないが、被測定回路の電流値をアナログ量
として検出するセンサーとしては致命的な欠点であつた
。 本発明は、この欠点を除去するためブリッジ回路の
2個直列な半導体磁気抵抗素子の各々にバイアス磁界を
加え、かつ被測定回路の電流によつて発生する磁界と、
上記バイアス磁界とが一方の半導体磁気抵抗素子には相
加的に他方の半導体磁気抵抗素子には減殺的に加わるこ
とにより、ブリッジ回路出力電圧が、被測定回路の電流
と比例することを特徴とした電流検出器にある。
Here, 1 and 1' are terminals connected to the circuit under test, 2 is a coil that generates a magnetic field proportional to the current flowing from terminals 1 and 1', 3 and 3' are semiconductor magnetoresistive elements, and 4 and 4' is a resistor, and 3, 3' and 4, 4' form a bridge circuit. Further, 6 is a differential amplifier with high input impedance, 7 is its output, and 8 is a terminal for supplying DC voltage to the bridge circuit and the differential amplifier. When current flows through the coil 2, the magnetic field generated by the coil 2 is applied to the semiconductor magnetoresistive element 3',
Its resistance value changes, generating a voltage between bridge outputs a and a'. This voltage is amplified by a differential amplifier 6. R is the resistance value when the magnetic field applied to the semiconductor magnetoresistive element 3' is zero. , if the resistance value when the magnetic field is B is RB, then RB
/Ro is not proportional to the magnetic field until the magnetic field is equalized, as shown in the characteristic diagram of the magnetic field and resistance value of the element in FIG. Therefore, when the current flowing out from the circuit under test is small, the magnetic field applied to the semiconductor magnetoresistive element is low, and the bridge output voltage is not proportional to the current in the circuit under test. This fact does not pose much of a problem when used as a digital sensor that detects simple changes in current value, but it is a fatal drawback when used as a sensor that detects the current value of the circuit under test as an analog quantity. In order to eliminate this drawback, the present invention applies a bias magnetic field to each of the two series semiconductor magnetoresistive elements of the bridge circuit, and also applies a magnetic field generated by the current of the circuit under test.
The bias magnetic field is applied additively to one semiconductor magnetoresistive element and destructively to the other semiconductor magnetoresistive element, so that the bridge circuit output voltage is proportional to the current of the circuit under test. It is in the current detector.

以下図面について説明する。The drawings will be explained below.

第2図は本発明に係る電流検出器の実施例の回路図であ
つて、1,1″は彼測定回路に接続される端子、2,2
″はコイルである。
FIG. 2 is a circuit diagram of an embodiment of the current detector according to the present invention, in which 1, 1'' are terminals connected to the measuring circuit, 2, 2
″ is a coil.

コイル2,2″が発生する磁界は3,3″の半導体磁気
抵抗素子の一方には磁石5,5″による磁界と相加的に
他方には減殺的に加わる様に構成する。4,4″は抵抗
、5,5″は電磁石または磁石、6は入力インピーダン
スの高い差動増幅器、7はその出力、8は直流電圧供給
端子である。
The magnetic field generated by the coils 2, 2'' is configured to be applied to one of the semiconductor magnetoresistive elements 3, 3'' in an additive manner to the magnetic field produced by the magnets 5, 5'', and to the other in a destructive manner.4, 4 '' is a resistor, 5 and 5'' are electromagnets or magnets, 6 is a differential amplifier with high input impedance, 7 is its output, and 8 is a DC voltage supply terminal.

3,3″は半導体磁気抵抗素子に加わる5,5″の電磁
石または磁石が発生する磁界の大きさは、その抵抗値変
化が磁界Bに比例する領域の値である(第3図の式以上
の値)次に、第2図をもとにブリッジ出力電圧を示す。
3.3" is the magnitude of the magnetic field generated by the 5.5" electromagnet or magnet that is applied to the semiconductor magnetoresistive element, and is the value in the region where the resistance change is proportional to the magnetic field B (from the equation in Figure 3) (value of) Next, the bridge output voltage is shown based on FIG.

第2図の半導体磁気抵抗素子3,3″と抵抗4,4″の
抵抗値および直流電圧端子7に加わる電圧をそれぞれR
l,R2,R3,R4Vとする。差動増幅器6の入力イ
ンピーダンスは、上記Rl,R2,R3,R4に比べて
大きい値である。この時ブリッジ出力電圧E。(第2図
のA,a″間の電圧)は次式で表わせる。ここでR3=
R4とし、磁石が発生する磁界のみが半導体磁気抵抗素
子に加わつたときの抵抗値ROとすると、コイルが発生
する磁界が、相加的および減殺的に加わつた場合の抵抗
値は次式のごとくである。
The resistance values of the semiconductor magnetoresistive elements 3, 3'' and the resistors 4, 4'' in FIG.
1, R2, R3, and R4V. The input impedance of the differential amplifier 6 is a larger value than Rl, R2, R3, and R4 described above. At this time, the bridge output voltage E. (The voltage between A and a″ in Figure 2) can be expressed by the following formula. Here, R3=
If R4 is the resistance value when only the magnetic field generated by the magnet is applied to the semiconductor magnetoresistive element, then the resistance value when the magnetic field generated by the coil is applied additively and subtractively is as shown in the following formula. It is.

ここで、Bは回路が発生する磁束密度であり、Sは比例
係数である。
Here, B is the magnetic flux density generated by the circuit, and S is the proportionality coefficient.

以上から(1)式は以下のごとくとなる。From the above, equation (1) becomes as follows.

(4)式において、Bは被測定回路電流に比例するから
、ブリッジ出力電圧は被測定回路の電流に比例すること
がわかる。
In equation (4), since B is proportional to the current of the circuit under test, it can be seen that the bridge output voltage is proportional to the current of the circuit under test.

以上説明した様に、本発明を適用することによりセンサ
ー出力電圧が被測定回路の電流に比例し、かつ被測定回
路の直流電位に関係なく上記の電流が検出可能な電流検
出器が構成出来る。
As described above, by applying the present invention, it is possible to construct a current detector in which the sensor output voltage is proportional to the current of the circuit to be measured, and the current can be detected regardless of the DC potential of the circuit to be measured.

【図面の簡単な説明】[Brief explanation of the drawing]

第1図は従来の非直線電流検出器の実施例の回路図、第
2図は本発明の実施例の回路図、第3図は半導体磁気抵
抗素子の磁界一抵抗特性図てある。 図において、1,1″・・・被測定回路に接続される端
子、2,2″・・コイル、3,3″・・・半導体磁気抵
抗素子、4,4″・・・抵抗、5,5″・・・電磁石ま
たは磁石、6・・・差動増幅器、7・・・その出力端子
、8・・・直流電圧供給端子である。
FIG. 1 is a circuit diagram of an embodiment of a conventional nonlinear current detector, FIG. 2 is a circuit diagram of an embodiment of the present invention, and FIG. 3 is a diagram of magnetic field-resistance characteristics of a semiconductor magnetoresistive element. In the figure, 1,1''...terminal connected to the circuit under test, 2,2''...coil, 3,3''...semiconductor magnetoresistive element, 4,4''...resistance, 5, 5''... Electromagnet or magnet, 6... Differential amplifier, 7... Output terminal thereof, 8... DC voltage supply terminal.

Claims (1)

【特許請求の範囲】[Claims] 1 被測定回路の電流に比例した磁界を発生する二つの
コイルにバイアス磁界を与える磁界形成部と、印加磁界
の大きさにより抵抗値を変える2個の直列半導体磁気抵
抗素子及び2個の直列抵抗からなりかつ前記2個の直列
半導体磁気抵抗素子の接続点と前記2個の直列抵抗の接
続点との間から出力電圧をとり出すブリッジ回路から構
成し、前記一方の半導体磁気抵抗素子に対しては前記電
流検出コイルが発生する磁界と前記バイアス磁界とが相
加的に、他方の半導体磁気抵抗素子に対しては減殺的に
加えることによりブリッジ出力に被測定回路の電流に比
例した電圧を発生する電流検出器。
1. A magnetic field forming unit that applies a bias magnetic field to two coils that generate a magnetic field proportional to the current of the circuit under test, two series semiconductor magnetoresistive elements whose resistance value changes depending on the magnitude of the applied magnetic field, and two series resistors. and a bridge circuit that extracts an output voltage from between the connection point of the two series semiconductor magnetoresistive elements and the connection point of the two series resistors, and for one of the semiconductor magnetoresistive elements. generates a voltage proportional to the current of the circuit under test at the bridge output by applying the magnetic field generated by the current detection coil and the bias magnetic field additively and destructively to the other semiconductor magnetoresistive element. current detector.
JP52033748A 1977-03-25 1977-03-25 current detector Expired JPS6046386B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP52033748A JPS6046386B2 (en) 1977-03-25 1977-03-25 current detector

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP52033748A JPS6046386B2 (en) 1977-03-25 1977-03-25 current detector

Publications (2)

Publication Number Publication Date
JPS53118175A JPS53118175A (en) 1978-10-16
JPS6046386B2 true JPS6046386B2 (en) 1985-10-15

Family

ID=12395029

Family Applications (1)

Application Number Title Priority Date Filing Date
JP52033748A Expired JPS6046386B2 (en) 1977-03-25 1977-03-25 current detector

Country Status (1)

Country Link
JP (1) JPS6046386B2 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3854457T2 (en) * 1987-07-07 1996-02-29 Nippon Denso Co Current detector arrangement with ferromagnetic magnetic resistance element.

Also Published As

Publication number Publication date
JPS53118175A (en) 1978-10-16

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