JP2004219294A - Current sensor and its manufacturing method - Google Patents

Abstract

A magnetic field measuring current sensor can be easily manufactured.
A toroidal coil (2) is wound around an insulated annular conductor (11) in which a part of a closed loop is cut off, one end of both conductors is connected, and the other end of both conductors is used as a detection terminal.
Alternatively, an insulated toroidal coil 22 is wound around the annular conductor 1 having a shape in which a part of the closed loop is cut out, one ends of these two conductors are connected, and the other ends of both conductors are used as detection terminals.
Alternatively, the coil 32 is wound around the linear center conductor 31. At this time, an insulating film is formed on at least one surface of both conductors. After connecting one end of both conductors and using the other end of both conductors as a detection terminal, the center conductor 31 is formed into a closed loop in which a part thereof is cut out.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a current sensor for measuring a current by measuring a magnetic field generated by the current, and a method for manufacturing the same.
[0002]
[Prior art]
FIG. 4 is a circuit diagram schematically showing the principle of a magnetic field measuring current sensor that measures a current from the measurement of a magnetic field generated by the current. In FIG. 4, a toroidal coil 2 as a second conductor is wound around an insulator core 3 made of an insulator having a shape in which a part of a ring is cut away. Has a buried annular conductor 1 as a first conductor in its length direction, so that the annular conductor 1 also has a partially cut-out annular shape.
One end of the annular conductor 1 and one end of the toroidal coil 2 are electrically connected. The other end of the annular conductor 1 and the other end of the toroidal coil 2 serve as a detection terminal 4. An output signal is obtained by processing the signal extracted from the detection terminal 4 by the signal processing circuit 5. In the current sensor having such a structure, a current circuit 6 penetrates a central portion of the toroidal coil 2, and when a current to be measured flows through the current circuit 6, a magnetic field generated around the current to be measured is generated. If the circuit is integrated by the toroidal coil 2, the current value can be obtained according to the law of circuit integration of ampere (for example, see Non-Patent Document 1).
[0003]
The toroidal coil 2 itself acts as one turn with respect to a magnetic field due to a current outside the toroidal coil or an external magnetic field, thereby causing a measurement error. Therefore, in order to cancel this error, a one-turn conductor is provided in series with the toroidal coil 2 in the opposite direction to the toroidal coil 2. This is the annular conductor 1. The annular conductor 1 is desirably located at the center of the winding diameter of the toroidal coil 2 wound therearound, and deviation from the center causes an error.
The current sensor having the above-described structure can measure a current in a state in which the current sensor is not in electrical contact with the current circuit 6, and the current sensor 6 can be measured without opening the current circuit 6 by using the cutout portion of the ring. Can be attached, so that there is an advantage that handling and measurement can be easily performed.
[0004]
[Non-patent document 1]
Ray WF & Hewson CR "High Performance Rogowski Current Transducers" Conf Rec IEEE Ind Appl Conf. 5 p. 3083-3090
[0005]
[Problems to be solved by the invention]
FIG. 5 is a partially enlarged structure diagram showing a partially enlarged structure of the conventional current sensor shown in FIG. In FIG. 5, the insulator core 3 having a shape in which a part of a ring is cut out has a circular cross section, but may have a shape other than a circle. The annular conductor 1 is located at the center of the circle. For this purpose, a slit 3S for inserting the annular conductor 1 is formed in the insulator core 3. Alternatively, in order to accommodate the annular conductor 1 in the insulator core 3, a hollow insulator may be formed in an annular shape instead of the slit 3S. However, in any case, it takes a lot of trouble and time to produce the insulator core 3 having a specific shape. In particular, when detecting a very small current, the size of the current sensor often needs to be extremely small, so that it is difficult to manufacture the hollow or slit insulator core 3 with good accuracy. There is a disadvantage that the price also rises.
[0006]
Therefore, an object of the present invention is to make it easy to manufacture a magnetic field measuring current sensor.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a current sensor and a method of manufacturing the same according to the present invention include:
A second conductor made of a non-magnetic conductor is wound around a first conductor made of a non-magnetic conductor in which a part of a closed loop is cut away while being insulated from the first conductor. One end of the two conductors is connected, and the other end of the first conductor and the other end of the second conductor are used as detection terminals.
Insulation between the first conductor and the second conductor wound therearound is achieved by forming an insulating film on the surface of the first conductor. Alternatively, this is achieved by forming an insulating film on the surface of the second conductor.
[0008]
A second conductor made of a non-magnetic conductor is wound around the first conductor made of a non-magnetic conductor in a state insulated from the first conductor, and one end of the first conductor is connected to one end of the second conductor; After the other end of the first conductor and the other end of the second conductor are used as detection terminals, the first conductor is formed into a closed loop shape with a portion cut away.
The insulation between the first conductor and the second conductor wound around the first conductor is achieved by forming an insulating film on at least one of the surfaces of the first conductor and the second conductor.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a structural view showing a first embodiment of the present invention. In FIG. 1, an insulating annular conductor 11 as a first conductor having a shape in which a part of an annular portion is cut out has an insulating coating formed by applying and baking an insulating paint on a surface of a nonmagnetic conductor (for example, copper). The wire is a wire generally called an enameled wire. When the toroidal coil 2 as a second conductor, which is a wire made of a nonmagnetic conductor, is wound around the insulated annular conductor 11, the insulated annular conductor 11 and the toroidal coil 2 are insulated. It can be positioned at the center of the winding diameter of the toroidal coil 2. A current sensor is formed by connecting one end of the insulated annular conductor 11 to one end of the toroidal coil 2 and using the other end of the insulated annular conductor 11 and the other end of the toroidal coil 2 as the detection terminals 4. be able to.
[0010]
FIG. 2 is a structural view showing a second embodiment of the present invention. In FIG. 2, the annular conductor 1 as a first conductor having a shape in which a part of an annular portion is cut out is a wire made of a nonmagnetic conductor. On the other hand, an insulating coating is formed by applying and baking an insulating paint on the surface of a wire made of a non-magnetic conductor to form an insulating toroidal coil 22 as a second conductor using a wire generally called an enameled wire. When wound around the ring conductor 1, the ring conductor 1 and the insulating toroidal coil 22 are insulated, and the ring conductor 1 can be positioned at the center of the winding diameter of the insulating toroidal coil 22. If the insulated toroidal coil 22 is used, it is possible to omit the turn-to-turn insulation in the case where the coil is wound many times and the coil is closely wound.
[0011]
A current sensor is formed by connecting one end of the annular conductor 1 to one end of the insulating toroidal coil 22 and using the other end of the annular conductor 1 and the other end of the insulating toroidal coil 22 as the detection terminals 4. Can be.
FIG. 3 is a structural view showing a third embodiment of the present invention. In FIG. 3, a center conductor 31 as a linear first conductor is a wire made of a nonmagnetic conductor. On the other hand, the coil 32 as a second conductor, which is a wire made of a non-magnetic conductor, is wound around the center conductor 31. At this time, an insulating paint is applied and baked on the surface of either the center conductor 31 or the coil 32. When the insulating film is formed, the center conductor 31 and the coil 32 are insulated, and the center conductor 31 can be positioned at the center of the winding diameter of the coil 32. If an insulating film is formed on the surface of the coil 32, inter-turn insulation when the coil 32 is wound tightly can be omitted.
[0012]
A current sensor is formed by connecting one end of the center conductor 31 to one end of the coil 32 and using the other end of the center conductor 31 and the other end of the coil 32 as the detection terminals 4. In this state, if one end of the center conductor 31 and the other end are formed into an annular shape without contacting each other, a current sensor can be obtained.
The closed loop shape in the present application includes various shapes such as an annular shape and a polygonal shape (for example, a hexagonal shape or a square shape).
[0013]
【The invention's effect】
Conventional magnetic field measurement current sensors process the insulator into an annular shape, make it hollow or machine a slit, store the conductor in the center of the insulator, and wind a toroidal coil around the annular insulator. However, a small current sensor for measuring a small current has a problem that it takes time and effort to manufacture, and it is difficult to position the first conductor at the center of the winding diameter of the toroidal coil so that a measurement error does not occur. There were some inconveniences. On the other hand, the present invention provides easy insulation by using a so-called enameled wire whose surface is coated and baked with an insulating film for either one of the first conductor and the toroidal coil having a closed loop shape. Therefore, the first conductor can be easily positioned at the center of the winding diameter of the toroidal coil. Further, by winding a coil around a linear conductor serving as the center and then processing the linear conductor into a closed loop, an effect that the production of the magnetic field measuring current sensor can be further facilitated is obtained.
[Brief description of the drawings]
FIG. 1 is a structural diagram showing a first embodiment of the present invention. FIG. 2 is a structural diagram showing a second embodiment of the present invention. FIG. 3 is a structural diagram showing a third embodiment of the present invention. 4 is a circuit diagram schematically showing the principle of a magnetic field measuring current sensor for measuring a current from the measurement of a magnetic field generated by the current. FIG. 5 is a partially enlarged view of the structure of the conventional current sensor shown in FIG. Partial enlarged structure diagram [Explanation of symbols]
Reference Signs List 1 annular conductor as first conductor 2 toroidal coil 3 as second conductor 3 insulator core 3S slit 4 detection terminal 5 signal processing circuit 6 current circuit 11 insulated annular conductor 22 as first conductor 22 insulation as second conductor Toroidal coil 31 Center conductor 32 as first conductor 32 Coil as second conductor

Claims (5)

A second conductor made of a non-magnetic conductor is wound around a first conductor made of a non-magnetic conductor having a shape in which a part of a closed loop is cut away while being insulated from the first conductor,
A current sensor, wherein one end of the first conductor is connected to one end of a second conductor, and the other end of the first conductor and the other end of the second conductor are used as detection terminals. The current sensor according to claim 1,
A current sensor, wherein insulation between the first conductor and a second conductor wound around the first conductor is provided by a first conductor having an insulating film formed on a surface thereof. The current sensor according to claim 1,
A current sensor, wherein insulation between the first conductor and a second conductor wound around the first conductor is provided by a second conductor having an insulating film formed on a surface thereof. Winding a second conductor made of a non-magnetic conductor insulated from the first conductor around a first conductor made of a linear non-magnetic conductor;
Connecting one end of the first conductor and one end of the second conductor, and using the other end of the first conductor and the other end of the second conductor as a detection terminal;
Forming the first conductor into a closed loop shape with a partially cut-out shape;
A method for manufacturing a current sensor, comprising: The method for manufacturing a current sensor according to claim 4,
The insulation between the first conductor and the second conductor wound around the first conductor uses a nonmagnetic conductor having an insulating film formed on at least one surface of the first conductor or the second conductor. How to make a sensor.

Images