JPH02194363A - Current sensor - Google Patents

Abstract

PURPOSE:To maintain high breakdown strength and to detect in high sensitivity by arranging a pair of magnetic lines in parallel separated with a space, furnishing with windings so that the directions of magnetic fields based on the coil currents of each coil are same and providing a current detecting part in that space. CONSTITUTION:At the time of current detection, a lead wire 13 in which the current to be detected is made to flow is arranged in the current detecting part S1 provided in the space between the pair of the magnetic lines 6, 7. The magnetic field depending on the direction of a current generated around the conductor 13 is intersected with the coils 8, 9 which are wound on the magnetic lines 6, 7 arranged in parallel. These coils 8, 9 are furnished with the windings so that the directions of the magnetic fields based on the coil currents are same, and the magnetic field generated around the lead wire 13 acts to the magnetic field generated in one coil 8 as adding and to the magnetic field generated in another coil 9 as differential. Therefore, inductance values of the coils 8, 9 are different, then the current detection can be made by detecting this difference.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention mainly relates to a current sensor for detecting direct current, in which a pair of magnetic wires wrapped around a coil are arranged at a distance, and a pair of magnetic wires is arranged at a distance. Each coil is wound so that the magnetic field direction of the coil current is in the same direction, and by providing a current detection section within the interval between the paired magnetic wires, DC current can be detected without being affected by external magnetic fields. It ensures high voltage resistance and enables detection with high sensitivity.

<Prior Art> Unlike alternating current sensors, direct current sensors cannot use a transformer in the detection section, and their configurations tend to be relatively complex.

4 to 6 show conventional DC current sensors. First, FIG. 4 shows the current 11 to be detected.
Insert detection resistor 1 in column 031 to the flowing line.1.
・This is a circuit configuration in which the potential difference appearing across the detection resistor 1 is detected through an amplifier circuit A or the like.

In the fifth section, a gap G1 is provided in a part of the core 3 around which the current detection coil 2 is wound, and a magnetoelectric transducer f4 such as a Hall element or a magnetoresistive element is arranged in this cap G1.・The output of the 1i11 electric conversion element 4 is sent to the amplifier circuit A゛τ
It is designed to output by τ amplification.

Next, FIG. 6 shows a current sensor that is often used in telephone communication lines, and has a configuration in which a reed relay 5 is inserted into the communication line through which the current 1 to be detected flows. The REIT relay 5 includes an excitation winding 51 that is connected in series with the communication line.
It is provided with a lead contact 52 that turns on and off under the action of the magnetic field generated by the excitation winding 51. A DC current on which an AC component such as a voice current is superimposed flows through the communication line. In order to prevent the impedance of the winding part of the relay relay 5 from interfering with this alternating current component, a capacitor C4 is connected to the magnetic winding 51 of the relay relay 5 and the MI column to bypass the alternating current component. has been done. R, l: i surge suction 14
This is a barista for 5+.

<Problem to be solved by the invention> However, it is necessary to electrically insulate the detection circuit from the electric circuit through which the current sensors l and j shown in FIG. 4 and the current I to be detected flows. There are problems such as the fact that the current 11 does not change due to the potential of the line through which the current 11 flows, making it difficult to maintain the withstand voltage of the detection section, and causing loss due to the detection resistor R1.

In the N-flow sensor shown in Fig. 5, in order to detect a minute current, the number of turns of the detection coil 2 must be increased, which increases the resistance and inductance of the detection coil 2, and increases the current Since it has the same potential as the line through which tl flows, there are problems such as difficulty in maintaining a withstand voltage depending on the line potential.

In the current sensor shown in Fig. 6, the excitation winding of the reed relay 5, which is the detection end, is connected in series to the communication line, so a large capacity capacitor C1 to bypass the AC component and a varistor R5 for surge absorption are installed. There are problems such as the necessity of

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a current sensor capable of solving the above-mentioned conventional problems and detecting direct current with high sensitivity while ensuring high withstand voltage without being affected by external magnetic fields. It is.

<Means for solving the problems> In order to solve the above-mentioned conventional problems, the present invention provides the following:
A current sensor comprising: a pair of magnetic wires wrapped with a coil; and a circuit that generates an output corresponding to a change in inductance value of the coil due to a current to be detected, the pair of magnetic wires are spaced apart from each other. They are arranged so that they are parallel to each other, and each coil of the pair of magnetic wires is wound so that the direction of the magnetic field due to the coil current is in the same direction, and within the interval between the magnetic wires of the pair. It is characterized in that it has a current detection section.

Effect> For current detection, a conductor wire through which the current to be detected is flowing is placed in the current detection section provided within the interval between the pair of magnetic wires. A magnetic field is generated around the conductor, which depends on the direction of the current. Since the magnetic wires of the pair are arranged parallel to each other with an interval between them, the magnetic field generated around the conductor wire in the current detection section that is set within the interval between the magnetic wires of the pair is It interlinks with the coil wound on.

Each coil of a pair of magnetic wires is wound so that the direction of the magnetic field due to the coil current is in the same direction, so the magnetic field generated around the conductor wire is added to the magnetic field generated by the other coil. In other words, it acts differentially on the 6n field generated by the other coil. Therefore, the inductance values of the respective coils of the pair of magnetic wires become different from each other depending on the detected electric discharge value. Therefore, by detecting the difference between the inductance values of both coils, Tl? m can be detected.

In the current sensor according to the present invention, since the conductor through which the current to be detected flows is an external circuit, the withstand voltage as a sensor is guaranteed by the withstand voltage of the conductor. Moreover, in response to an external magnetic field such as the earth's magnetic field that is applied to the pair of magnetic wires from the same direction, the inductance value of each coil changes by the same amount in the same direction and does not make any difference. Therefore, in the present invention, which detects current from the difference in inductance values, there is no influence of external magnetic fields, and it is possible to detect minute magnetic fields with high precision.

<Example> FIG. 1 shows an example of a current sensor according to the present invention. In the figure, 6 and 7 are magnetic wires, 8 and 9 are coils, IO is an oscillation circuit, 11 is an averaging circuit, and 12 is a differential amplifier circuit.

The magnetic wires 6 and 7 are made of a magnetic material having a small coercive force He, for example, an amorphous magnetic wire, and are independent wires having substantially the same length. Each of these magnetic lines 6.7 is
The coils 8 and 9 are wound and arranged so as to be substantially parallel to each other with a distance d between them. paired lin sex line 6
The interval d between -7.

A current detection section S1 is provided inside. When detecting current, the current to be detected (■1) is stored in this current detection section S1.
A conducting wire 13 is arranged through which the flow of the current occurs.

Coils 8 and 9 have a magnetic field φ caused by coil currents I8 and IO.
8 and φ9 are wound in the same direction. The coils 8.9 have their ends commonly connected to the DC power supply terminal 14, and the other ends connected to the oscillation circuit 10.

The oscillation circuit 10 shown in the embodiment is composed of an unstable multivibrator, and has a coil 8.9 connected to the collector of a transistor 101.102. The emitters of transistors 101.102 are connected to resistors 103.1 and 103.1, respectively.
04, and one transistor 101 (
or 102) to the base of the other transistor 102
(or 101) via a parallel circuit 105 (or 106) of a capacitor and a resistor, an astable multivibrator is constructed. Then, the emitter voltages of the transistors 101 and 102 are converted into a DC voltage by an averaging circuit 11, and the DC voltage is input to a differential amplifier circuit 12 to obtain a differential output voltage from an output terminal 15. 111.112 is resistance, 113
．． 114 is a capacitor.

Next, the operation will be explained with reference to FIG. Current detection part S
If a current 11 in the direction of arrow a is flowing through the conductor 13 disposed at 1, a magnetic field φ1 that depends on the direction of the current 11 is generated around the conductor 13 according to the right-handed screw rule.

Since the pair of magnetic wires 6.7 are arranged parallel to each other with an interval d, a magnetic field φ8 generated around the conductive wire 13 in the current detection unit S1 set within the interval d.
intersect with a coil 8.9 wound around a pair of magnetic wires 6.7.

Here, each coil 8.9 of the pair of magnetic wires 6.7 is wound so that the directions of the magnetic fields φ8 and φ9 due to the coil current 8 and IO are in the same direction. The magnetic field φ8 generated in the coil 9 is the magnetic field φ9 generated by the coil 9.
It acts additively on the magnetic field φ8 generated by the coil 8, and differentially acts on the magnetic field φ8 generated by the coil 8. Therefore, the magnetic wire 7 is almost magnetically saturated on the coil 9 side, and the inductance value becomes significantly small, so that a large difference occurs between the inductance value of the coil 8 and the inductance value of the coil 9. The unstable multivibrator 10 performs an oscillation operation in which the larger the difference in inductance values, the higher the operating frequency and the higher the voltage between each emitter. Therefore, by averaging the outputs of the transistors 101 and 102 in the averaging circuit 11 and amplifying and extracting the difference in the differential amplifier 12, it is possible to detect the current 2 flowing in the conducting wire 13.

When the direction of the current (1) flowing through the conducting wire 13 is reversed, the role of the coil 8.9 is reversed.

The current sensor according to the present invention has a current to be detected;
Since the conductor 13 flowing through it is outside the circuit, the conductor 13
The circuit is not affected by Further, the withstand voltage as a current sensor is guaranteed by the withstand voltage of the conducting wire 13. Moreover, the external magnetic field φb such as the earth's magnetic field applied from the same direction to the pair of magnetized wires 6.7 acts on each coil 8.9 in the same way and does not cause a change in the inductance value. Therefore, it is no longer affected by the external magnetic field φb, and only the current 11 flowing through the conducting wire 13 can be detected with high precision.

When the current I to be detected is small, it can be easily detected by increasing the number of turns of the conducting wire 13, as shown in FIG. The conducting wire 13 is wound so as to surround the set of the magnetic wire 6 and the coil 8, or the set of the magnetic wire 7 and the coil 9.

<Effects of the Invention> As described above, the present invention provides a current sensor comprising a pair of magnetic wires around which a coil is wound, and a circuit that generates an output corresponding to a change in the inductance value of the coil due to a current to be detected. The pairs of magnetic wires are arranged parallel to each other with a gap between them, and each coil of the pair of magnetic wires is wound so that the direction of the magnetic field due to the coil current is in the same direction. Since it has a current detection part within the interval between the paired magnetic wires, it provides a current sensor that can detect DC current with high sensitivity without being affected by external magnetic fields, ensuring high withstand voltage. can.

[Brief Description of the Drawings] Fig. 1 is a circuit diagram showing an embodiment of the current sensor according to the present invention, Fig. 2 is a diagram showing the basic operation of current detection, and Fig. 3 is a diagram showing the main parts of another embodiment. The diagrams showing the configuration, FIGS. 4 to 6, are diagrams showing a conventional current sensor. 6.7...Magnetic wire 8.9...Coil S,
...Current detection section

Claims (4)

[Claims] (1) A current sensor comprising a pair of magnetic wires wrapped around a coil and a circuit that generates an output corresponding to a change in the inductance value of the coil due to a current to be detected, the pair of magnetic wires having an interval between them. The coils of the pair of magnetic wires are wound so that the direction of the magnetic field due to the coil current is in the same direction, and the magnetic wires of the pair are arranged parallel to each other with a distance between them. A current sensor comprising a current detection section within an interval of. (2) The current sensor according to claim 1, wherein the circuit includes an oscillation circuit whose oscillation output characteristics change according to changes in the inductance value of the coil. (3) The current sensor according to claim 2, wherein the oscillation circuit is a multivibrator. (4) The current sensor according to claim 1, 2, or 3, wherein the magnetic wire is made of an amorphous magnetic material.