JPS58165058A - Insulation type current detector - Google Patents

Abstract

PURPOSE:To achieve a measurement without temperature error by a method wherein a current to be measured flows to the primary winding of a transformer with a square magnetic saturation property, an triangular waveform current is applied to the secondary winding thereof and the arithmetic mean of the secondary winding current is determined when a positive or negative impulse develops in the tartiary winding. CONSTITUTION:A transformer 1 is built up of a core with a rectangular hysteresis property and has windings T1-T3. Current Ii to be measured flows through the winding T1 and a current proportional to an arbitrary input voltage from a current-voltage converter 2 does through the secondary winding T2. A D/A converter 3 generates a voltage according to any numerical signal of digital indication and a control circuit 4 provides a triangular waveform current to the winding T2 through the converters 3 and 2. The circuit 4 also detects current flowing through the winding T2 when a positive or negative impulse develops in the output of the winding T3 and a value proportional to the arithmetic mean of both currents detected is outputted as current Ii in digital indication. Thus, an insulation type current detector with limited errors against changes in the environmental temperature and with a simple adjustment can be obtained.

Description

【発明の詳細な説明】 本発明は種々の計測において、電流信号を絶縁して測定
する電流検出器に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a current detector that insulates and measures current signals in various measurements.

従来、絶縁して電流を検出する場合は、（１）電磁方式
によるサンプリング方による絶縁検出を行う変換器等の
能動回路を持たせて、−担検出してかトカプラや絶縁ト
ランスを用いて絶縁してから測定系に測定結果を伝達さ
せる方法か％（３））ランス□ す、トランスのコアの飽和特性カーブが除々に変化する
ことを型用して、二次憚巻線あるいは更に三次巻線を用
いてその飽和特性の微妙な変化を検巻線に被測定電流を
流し、二次巻線の交流的定数を監糟１しながら三次巻線
に一次巻線の被測定電流を打消す方向に電流を流して、
二次巻線の交流定数が一定となるように三次巻線の電流
を調整し、その三次巻線の電流を知ることによって一次
巻線の電流を測定する方法、等が一般的であった。Conventionally, when detecting current with insulation, (1) an active circuit such as a converter that performs insulation detection using an electromagnetic sampling method is installed, and the -carrier is detected and isolated using a tocoupler or isolation transformer. Is there a way to transmit the measurement results to the measurement system? The current to be measured is passed through the winding to detect subtle changes in its saturation characteristics using a wire, and the current to be measured in the primary winding is canceled out to the tertiary winding while monitoring the alternating current constant of the secondary winding. Pass a current in the direction of
A common method was to adjust the current in the tertiary winding so that the AC constant of the secondary winding was constant, and then measure the current in the primary winding by knowing the current in the tertiary winding.

しかし、（１）の方法は機械的可動部分があり高信頼度
を得られない、（２１の方法は、使用部品点数が多く、
かつ、多数の電流を個々に絶線して測定する場合に％特
に・各測定点ごと坪個別の部品が多く必要となる。（３
）、　（４１の方法は温度によるトランス等部品の特性
が変化するために生じる誤差を防ぐこと、シよび、部品
側々の特性のバラツキを補正するための調整が困難下あ
った。However, method (1) does not have high reliability due to mechanically moving parts, (method 21 uses a large number of parts,
In addition, when measuring a large number of currents by disconnecting them individually, a large number of individual parts are required for each measurement point. (3
), (The method of No. 41 has difficulty in preventing errors caused by changes in characteristics of components such as transformers due to temperature, and in making adjustments to correct variations in characteristics among components.

したがりて、本発明の目的は温度による誤差が少なく調
整の容島な絶縁式電流検出器を提供することである。　
　　　　　□・・″ 本発明によれば、パー９：ｉイ等によって得られ÷ る矩形飽和特性のコアを用、：、、：、またトランスを
使用することと、双方向の磁束に対する磁気飽和点を利
□ｔ”、Ｂｅ＆によｎ、＊ｍａ’毎□５８，８ヶ、□の
電流を個々に絶縁する場合でも使用する部品点数が少く
、環境温度の変化に対する誤差も少く、調整も筒単にで
きる絶縁式電流検出器を得ることができる。SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an insulated current detector that has less temperature-related errors and is easy to adjust.
□...'' According to the present invention, a core with a rectangular saturation characteristic obtained by Par9:i, etc. is used, and a transformer is used, and the magnetic saturation point for bidirectional magnetic flux is Even when insulating individual currents of □t'', Be&, *ma', 58,8 pieces, □, the number of parts used is small, the error due to changes in environmental temperature is small, and adjustment is easy. A simple isolated current detector can be obtained.

本発明の一実施例を＠１図に示し、これを参照して本発
明の詳細な説明する１図で１は矩形ヒステリシス特性を
有するコアを用いてＴ１巻線Ｔ２巻線％Ｔ３巻線を有す
るトランス、２は任意の入力電圧に比例した電流を１２
巻線に流す電流電圧変換器、３は任意のデジタル表示の
数値信号に応じて電圧を発生させるＤＡ変換器、４はＤ
Ａ変換器３と電圧電流変換器２を介してＴ２に三角波形
電流を与えまた、Ｔ３巻線の出力において正インパルス
出現時点ｔｒと負インパルス出現時点ｔ（１に１２巻線
を流れる電流（Ｉｒ）ｒ、（Ｉｒ）ｄを検出して、（Ｉ
ｒ）ｒと（Ｉｒ）ｄの中間値を求めその老倍を被測定電
流！、、ｉとしてデジタル表示値を出力する制御回路で
グー。One embodiment of the present invention is shown in Figure @1, and the present invention will be explained in detail with reference to Figure 1. In Figure 1, T1 winding, T2 winding, % T3 winding are formed using a core having a rectangular hysteresis characteristic. A transformer with 12 current proportional to any input voltage, 2
A current-voltage converter that flows through the winding; 3 is a DA converter that generates a voltage according to an arbitrary digital display numerical signal; 4 is D
A triangular waveform current is applied to T2 via the A converter 3 and the voltage-current converter 2, and the current flowing through the 12th winding (Ir )r, (Ir)d, and (I
Find the intermediate value between r)r and (Ir)d and multiply it as the current to be measured! ,,Goo with the control circuit that outputs the digital display value as i.

第２図は巻線　１（巻数Ｔ１）に被測定電流１１が流れ
ることによ’Ｉ　）ランスのコアに与エラれる起磁ｈＩ
ｉｘＴｘと、巻線Ｔ２（巻数Ｔ２）に流れる既知の三角
波形電流Ｉｒによりトランスのコアに与えられる起磁力
ＩｒＸＴ２ｓ　　それ等の起磁力の合成起磁力ＩｒｘＴ
ｓ＋Ｉ五×Ｔ１（点線表記）、および、コアの磁気飽和
レベル（ａｎとＳｐ）を上図に、Ｔｓ巻線に誘起される
インパルス電圧を下図に同一時間関係で記載したもので
ある。■ｉ待時間対する変化率に比べて充分に速い４懸
周波数で三角波形電流Ｉｒを発生させ、　Ｉｒによる起
磁力ＩｒＸＴ１と被測定電流ＩＬによる起磁力ｌ１ｘＴ
。Figure 2 shows the magnetomotive force hI applied to the core of the lance due to the current 11 to be measured flowing through winding 1 (number of turns T1).
ixTx and the magnetomotive force IrXT2s given to the core of the transformer by the known triangular waveform current Ir flowing through the winding T2 (number of turns T2) The composite magnetomotive force IrxT of these magnetomotive forces
s+I5×T1 (dotted line notation) and the magnetic saturation level of the core (an and Sp) are shown in the upper figure, and the impulse voltage induced in the Ts winding is shown in the same time relationship in the lower figure. ■ Generate a triangular waveform current Ir at a frequency that is sufficiently fast compared to the rate of change with respect to i waiting time, and generate a magnetomotive force IrXT1 due to Ir and a magnetomotive force l1xT due to the current to be measured IL.
.

との和が必ず不飽和領域を横断するように工ｒｘ’ｒｌ
を充分に大きく設定しておき、■・の傾斜が一分に直線
性が良く、トランス１のコアの矩形ヒステリシスが充分
に矩形を呈すれば、巻線Ｔ１と巻線Ｔ２による合成起磁
力が、一方の飽和領域から不飽和領域を通過して、もう
一方の飽和領域に達した時に磁束反転が一生して、その
反転極性に応じた極性のインパルス電圧が巻線Ｔ３に誘
起される。rx'rl so that the sum always crosses the unsaturated region.
If is set to a sufficiently large value, the slope of . When the magnetic flux passes from one saturated region to the unsaturated region and reaches the other saturated region, the magnetic flux is reversed, and an impulse voltage having a polarity corresponding to the reversed polarity is induced in the winding T3.

仁のインパルス電圧Ｖの出現タイミングのうち正側イン
パルス出現時点ｔｒは合成起磁力が飽和磁束８　、に打
ち勝つレベルに達した時であり、負（２）インパルス出
現時点ｆｄＦｉ＋成起磁力が飽和磁束Ｓ、に打ち勝つレ
ベルに達した時であり７％　Ｔ。Of the appearance timings of the impulse voltage V, the positive impulse output point tr is when the composite magnetomotive force has reached a level that overcomes the saturation magnetic flux 8, and the negative (2) impulse output point fdFi + product magnetomotive force is the saturation magnetic flux S. This is when you reach a level where you can overcome , which is 7%T.

とＴｄそれぞれ、の時点で巻線Ｔ！に流れていた電流（
工ｒ）ｒと（Ｉｒ）ａと表記すると、（ＩｉｘＴｌ）＋
（（Ｉｒ）ｒＸＴＩ）＝８ｎ（Ｉ’ＸＴ＊）”（（Ｉｒ
）ｄＸ’ｌ”、）＝Ｓｐ’となる。and Td, respectively, at the time of winding T! The current flowing in (
When written as (IixTl)+
((Ir)rXTI)=8n(I'XT*)"((Ir
)dX'l'', )=Sp'.

磁気コアの飽和磁束は両極性とも絶対値は一致、するか
ら Ｓｎ二ｓ。The saturation magnetic flux of the magnetic core has the same absolute value for both polarities, so Sn2s.

関係がある。There is a relationship.

故に （ＩｉｘＴｔ）”（（Ｉｒ）ｒｘＴｌ）＝−（ＩｉｘＴ
ｌ）−［（Ｉｒ）ｄさＴ鵞］ の等式が、成孔立つ。Therefore, (IixTt)”((Ir)rxTl)=−(IixT
The equation: l)-[(Ir)dSaT鵞] is established.

これを調理すれば、 ？等式が得られる。　　　　　。If you cook this, ? The equation is obtained.　　　　.

この事から、制御回路４で、しかるべき負の値としかる
べき正の値を設定してその２つの値の間を一定変化率で
誓増および誓減を繰返すディジタル値号を発生して、そ
のディジタル値をＤＡ変換器３により、三角波形電圧に
変換して４更に−その三角波形電圧を電圧電流変換器１
に入力して、三角波形電流を得て、この電流をトランス
ｌの巻線Ｔ２に流し、巻線Ｔ３に表われるインパルス電
圧Ｖを制御回路４にて検出し、（Ｉ、）ｒと（Ｉｒ）ａ
を求めれば、被測定電流Ｉｉの解を得ることができる。From this, the control circuit 4 sets an appropriate negative value and an appropriate positive value, and generates a digital value that repeats increasing and decreasing values between the two values at a constant rate of change. The digital value is converted into a triangular waveform voltage by the DA converter 3, and then the triangular waveform voltage is converted to the voltage-current converter 1.
to obtain a triangular waveform current, this current is passed through the winding T2 of the transformer l, the impulse voltage V appearing on the winding T3 is detected by the control circuit 4, and (I,)r and (Ir )a
By calculating , the solution for the current to be measured Ii can be obtained.

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

第１図は本発明の一実施例を示す図。第２図は第１図の
動作を説明するための図。FIG. 1 is a diagram showing an embodiment of the present invention. FIG. 2 is a diagram for explaining the operation of FIG. 1.

Claims (1)

【特許請求の範囲】[Claims] 矩型磁気飽和特性のコアを使用した複数の巻線のトラン
スを用いて、被測定電流をそのト°ランスの第一の巻線
に流し、その被測定電流による起磁力と第二の巻線によ
る起磁力との合成起磁力がトランスのコアの磁束が片−
飽和領域から、不飽和領域を経て反対俸飽和領域まで反
転するだけの電流を第二の巻線に流して、磁束が片憚の
飽和領域から反対側の飽和領域に反転した時に第二の巻
線に流れていた電流と、磁束が反対ｌｌ１−和領域から
元の飽和領域に再度反転した時に第二のｅ線に流れてい
た電流を測定し、それぞれの電流の算術平均値に比例し
た値を被測定電流とすることを特徴とする絶縁式電流検
出器。Using a multi-winding transformer that uses a core with rectangular magnetic saturation characteristics, the current to be measured is passed through the first winding of the transformer, and the magnetomotive force due to the current to be measured and the second winding are The composite magnetomotive force with the magnetomotive force due to the magnetic flux of the core of the transformer is
A current sufficient to reverse from the saturated region to the opposite saturated region through the unsaturated region is passed through the second winding, and when the magnetic flux is reversed from the saturated region on one side to the saturated region on the opposite side, the second winding Measure the current flowing in the wire and the current flowing in the second e wire when the magnetic flux reverses again from the opposite ll1-sum region to the original saturation region, and calculate a value proportional to the arithmetic mean value of each current. An insulated current detector characterized in that the current to be measured is .