JP2021043102A - Current detector - Google Patents

Abstract

To provide a technique that can make a conductor or an output stable.SOLUTION: A curent sensor 100 detects a current, with a primary conductor BU, in which a detection target current is flowing, being inserted in the sensor. The current sensor 100 includes: a case body 102 for containing a device which detects a current, the case body having an insertion unit 108 for dividing the region around the inserted primary conductor BU by a surface extending in the insertion direction; and a rib 112 protruded from the surface of the insertion unit 108, the rib holding the positional relation between the case body 102 and the primary conductor BU in such a manner that the case body 102 is fastened to the primary conductor BU while being in contact with the primary conductor BU.SELECTED DRAWING: Figure 3

Description

The present invention relates to a current detector that performs detection with a conductor inserted.

Conventionally, a prior art of a current sensor that detects a current by inserting a conductor to be inspected is known (see, for example, Patent Document 1). In this prior art, a magnetic core formed in an annular shape is accommodated so as to be sandwiched between a main body case member and a lid member from both directions. At this time, the inside of the annular magnetic core is a through hole through which the conductor to be inspected is inserted, and the first wall member provided in the case member and the second wall member provided in the lid member make the through hole. By enclosing it heavily, the insulation between the conductor to be inspected and the magnetic core, magnetic sensor, etc. is ensured.

JP-A-2015-49061

Since the conductor to be inspected inserted through the through hole is in a free state in the current sensor of the prior art, both the current sensor and the conductor to be inspected are easily affected by vibration and external force generated in the usage environment. Therefore, there is a problem that the distance between the magnetic core or the magnetic sensor and the conductor to be inspected is not stable and the output characteristics become unstable.

Therefore, the present invention provides a technique for stabilizing a conductor and an output.

The present invention provides a current detector. The current detector of the present invention performs detection (output of a detection signal according to the detected current) in a state where a conductor through which the detected current flows is inserted. The current detector may include, for example, a magnetic core, a detection element, an output circuit, or the like as a device for detecting. The magnetic core converges the magnetic field generated by the flow of the detected current. An air gap can be provided in the magnetic core, and a detection element (Hall element, field probe, etc.) can be arranged in the air gap. Further, the magnetic core may be provided with a secondary winding. The detection element generates a signal (Hall voltage, feedback current) according to the magnetic field strength, processes this in the output circuit, and outputs it as a detection signal.

The current detector of the present invention houses the above-mentioned equipment in the main body. Further, the main body has an insertion portion through which the conductor is inserted, and the insertion portion divides the periphery of the conductor by a surface. The "face" here does not include something like a mere end face of a plate-like body (only the length of the plate thickness in the insertion direction), but has a certain length in the insertion direction (for example, the length of the insertion portion). It has a degree equivalent to the size). By partitioning the periphery of the conductor with such a surface having a certain length in the insertion direction, a large insulation distance from the conductor to the device housed in the main body can be secured (conversely, the insertion direction). The shorter the length of, the shorter the insulation distance).

Further, the current detector of the present invention includes a ridge formed so as to project from the surface of the insertion portion. Such a ridge body maintains a relative positional relationship between the main body and the conductor by fastening the main body to the conductor in a state of being in contact with the conductor inserted through the insertion portion. That is, since the current detector of the present invention has a structure in which the main body is fastened to the conductor, the position of the conductor in the insertion portion is stable. Further, it is not the surface of the insertion portion but the ridge body that comes into contact with the conductor in the fastened state. As mentioned above, the surface functions effectively to secure the insulation distance from the conductor, but since it does not come into direct contact with the conductor, the air layer efficiently conducts (transfers) heat from the conductor to the main body. It can be blocked. Since the contact with the conductor is performed by the ridge body, it is possible to make it difficult to transfer the heat from the conductor as compared with the surface contact.

On the other hand, when the insertion portion is composed of a surface, for example, when the main body is molded from resin, some mold (for example, a mold) is used, so that the surface after molding has a draft of the mold. It is common. For this reason, when trying to hold the conductor inserted through the insertion portion in contact with the surface, even if the contact surface on the conductor side is considered to be horizontal, the surface on the insertion portion side has a draft, so that amount. Since the tilt (angle) appears elsewhere, the tilt must be absorbed somewhere.

In this respect, since the present invention has a structure in which the ridges are in contact with the conductor, it is not necessary to provide a draft like a surface with respect to the ridges even when the main body is resin-molded. Therefore, when the contact surface on the conductor side is considered to be horizontal, the portion where the ridges are in contact can be formed as being horizontal like the contact surface on the conductor side. As a result, the relative positional relationship between the main body and the conductor can be maintained as desired (for example, horizontal surfaces / locations are parallel to each other), and some inclination may occur elsewhere. Absent.

The insertion portion may have a square tubular shape that surrounds the conductor with surfaces from four directions. Such a shape is suitable when the conductor (bus bar) to be inserted is, for example, a square bar or a flat plate. A fastening portion can be used for fastening the main body and the conductor. The fastening portion is formed on the main body so as to project from the insertion portion in the insertion direction of the conductor. The shape of the fastening portion may be any shape as long as it is suitable for fastening, but it has a surface facing the conductor, and this surface is connected to one surface of the insertion portion and extends in the insertion direction. Is preferable. In this case, the main body faces the conductor on the surface of the length (L1 + L2) obtained by adding the length of the surface of the fastening portion (L2) to the length of one surface of the insertion portion (L1). .. At this time, the ridge body is formed so as to project from the continuous surface of the insertion portion and the fastening portion. As a result, the contact between the conductor and the ridge body becomes about the same as the length of the continuous surfaces (L1 + L2), and the positional relationship can be reliably maintained by contacting the conductor with a sufficient length.

As described above, the ridge body contacts the conductor in the fastened state between the main body and the conductor and maintains the positional relationship between them. However, paying attention to the protrusion height (length) from the surface of the insertion portion. The larger the protrusion height, the farther the conductor is from the surface. This means that the insulation distance and physical distance from the equipment (magnetic core, magnetic sensor, output circuit, substrate, etc.) housed in the main body can be increased according to the protruding height of the projectile. To do.

Here, the inventors of the present invention are paying attention to the influence of the change of the primary voltage in the conductor on the change of the output signal in the current detector. Specifically, it is known that a steep voltage change of the detected current has a great influence as noise on the output signal from the current detector, and this is referred to as a dV / dt characteristic of the current detector or the output signal. It is considered that such dV / dt characteristics are due to the fact that noise is transmitted through the stray capacitance existing between the conductor and the output circuit, and if the waveform of the conductor voltage (primary voltage) is stepped at a certain timing. If it changes to a state (steep), the waveform of the output signal from the output circuit will also be disturbed at the same timing.

Assuming that the voltage change width is constant, such dV / dt characteristics are less susceptible to noise as the distance from the device including the output circuit to the conductor is larger, and conversely, the smaller the distance, the greater the effect of noise. I know I will receive it.

The current detector of the present invention can improve the dV / dt characteristics of the output signal according to the protruding height of the ridge body in contact with the conductor.

According to the present invention, the conductor and the output can be stabilized.

It is a perspective view which shows typically the structure of the current sensor 100 of one Embodiment. It is an exploded perspective view which shows schematic structure of the current sensor 100 of one Embodiment. It is a figure which showed the insertion of the primary conductor into the insertion part 108, and the fastening thereof. It is a perspective view which showed the current sensor 100 from the diagonally downward direction. It is a figure which showed the holding of the position of the primary conductor BU by a rib 112. It is a vertical sectional view of the case body 102. It is a perspective view which shows another form example of the current sensor 100 which shortened the length of the square tube part 102b. It is a figure which showed that the primary conductor BU is separated from the internal structure of the current sensor 100 according to the protrusion height DR of a rib 112. It is a figure which shows the result of observing the dV / dt characteristic of the current sensor 100. It is a figure which shows the result of observing the dV / dt characteristic of the current sensor 100. It is a figure which shows the relationship between the protrusion height DR of a rib 112, and the malfunction amount Vp-p appearing in an output waveform. It is a figure which shows the evaluation model of the dV / dt characteristic which changed the positional relationship between the primary conductor BU and the current sensor 100 from the arrangement of FIG. It is a figure which shows the result of observing the dV / dt characteristic of the current sensor 100 in the evaluation model of FIG. It is a figure which shows the result of observing the dV / dt characteristic of the current sensor 100 in the evaluation model of FIG. It is a figure which shows the relationship between the distance DS and the malfunction amount Vp−p appearing in an output waveform.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiment, a Hall IC type current sensor is given as an example of the current detector, but the present invention is not limited to this, and a magnetically balanced closed-loop type current sensor may be used. However, it may be a fluxgate type current sensor.

FIG. 1 is a perspective view schematically showing the configuration of the current sensor 100 of one embodiment. Further, FIG. 2 is an exploded perspective view schematically showing the configuration of the current sensor 100 of one embodiment.

As shown in FIGS. 1 and 2, the current sensor 100 includes a case body 102, and the case body 102 houses various components of the current sensor 100 inside. The components include a magnetic core 104, a circuit board 106, a Hall element 110, and the like. Note that only the main components are shown in FIGS. 1 and 2, and the other components are omitted as appropriate.

[Main body (case body)]
The current sensor 100 is used, for example, in the assembled state shown in FIG. The current sensor 100 has a case body 102 as a main body (body or housing), and has a peripheral wall portion 102a and a bottom wall portion 102g as its outer shell. The peripheral wall portion 102a and the bottom wall portion 102g constitute outer surfaces of the upper surface, both side surfaces, and the bottom surface of the current sensor 100 main body when viewed in the standing postures of FIGS. 1 and 2.

Inside the case body 102, an annular accommodating portion 102d is formed in a portion surrounded by the peripheral wall portion 102a and the bottom wall portion 102g. That is, various components such as the magnetic core 104, the circuit board 106, and the Hall element 110 are housed in the housing section 102d, and the housing section viewed in the horizontal direction in the standing postures of FIGS. 1 and 2. One end of 102d is open. The case body 102 has a back wall portion 102e on the side opposite to the opening of the housing portion 102d, and the other end of the housing portion 102d viewed in the horizontal direction is closed by the back wall portion 102e.

[Insert]
Further, an insertion portion 108 is formed in the case body 102, and the insertion portion 108 horizontally penetrates the center of the case body 102 (or the entire current sensor 100) when viewed in the standing postures of FIGS. 1 and 2. It is extending. That is, the case body 102 has a square tubular portion 102b inside the peripheral wall portion 102a and the bottom wall portion 102g, and the square tubular portion 102b has a square tubular shape so as to surround the insertion portion 108 with a surface from four directions. Is formed in. One end of the square tube portion 102b projects horizontally from the opening at one end of the accommodating portion 102d, and the other end is located on the same surface as the outer surface of the back wall portion 102e ((B) in FIG. 1). ..

[Fastening part]
Further, a fastening portion 102f is formed on the case body 102, and the fastening portion 102f projects in the horizontal direction from the outer surface of the back wall portion 102e when viewed in the standing postures of FIGS. 1 and 2. The fastening portion 102f is used to fasten the case body 102 (or the entire current sensor 100) to the primary conductor (not shown in FIGS. 1 and 2) inserted through the insertion portion 108. The fastening of the fastening portion 102f and the primary conductor will be described later.

In addition, a pair of brackets 102c are formed on the case body 102. The bracket 102c is located at the corner of the peripheral wall portion 102a and the bottom wall portion 102g on both sides as viewed in the standing posture of FIG. 1, and projects to both sides so as to straddle the peripheral wall portion 102a and the bottom wall portion 102g. ing. The pair of brackets 102c is used to install the current sensor 100, for example, in the upright position (used state) of FIG. 1, and the current sensor 100 is used for other equipment (eg, unsigned) not shown through the through holes (unsigned) of the bracket 102c. It can be fastened to generators, power plant equipment, etc. by screwing.

[Magnetic core]
As an example, the magnetic core 104 is composed of a pair of core members 104a and 104b having a horizontal U-shape. The pair of core members 104a and 104b are combined in a state where their respective tip surfaces (two) face each other, and an air gap 104c is formed at two locations between the tip surfaces. The magnetic core 104 converges the magnetic field generated by the detected current by inserting a primary conductor such as a bus bar through the insertion portion 108. Alternatively, a magnetic field is generated (converged) in the magnetic core 104 due to the conduction of the detected current to the primary conductor.

[Detecting element]
The two Hall elements 110 are arranged in the two air gaps 104c of the magnetic core 104 in the assembled state of the current sensor 100. The Hall element 110 has its magnetically sensitive surface facing the end faces (magnetic circuit cross sections) of the core members 104a and 104b, so that the voltage signal (magnetic detection) corresponding to the strength of the magnetic field generated (converged) in the magnetic core 104 Signal) is output.

[Circuit board]
The circuit board 106 has a lateral U-shape to match the shape of the accommodating portion 102d. In addition to the Hall element 110 mounted on the circuit board 106, an output circuit (current detection circuit) is formed by mounting various electronic components, IC chips, and the like (not shown). The output circuit amplifies the voltage signal output from the Hall element 110, for example, and also performs various electrical processes to output the current detection signal. An external connector 106a is mounted on the circuit board 106, and the external connector 106a protrudes (exposed) from the case body 102 in the assembled state of the current sensor 100. The current sensor 100 can supply power to the output circuit through the external connector 106a and output a current detection signal from the output circuit.

[Conductor insertion and fastening]
FIG. 3 is a diagram showing the insertion of the primary conductor BU into the insertion portion 108 and its fastening. FIG. 3A corresponds to a plan view of the current sensor 100 viewed in the standing posture of FIGS. 1 and 2, and FIG. 3B corresponds to a vertical sectional view thereof.

As described above, the current sensor 100 detects the primary current (current to be detected) with the primary conductor BU inserted through the insertion portion 108. The current sensor 100 of the present embodiment has a structure suitable for, for example, a square rod-shaped (long thick plate-shaped) primary conductor BU. That is, the square bar-shaped primary conductor BU has a rectangular cross section, and the upper surface, both side surfaces, and the lower surface are all flat. Assuming that such a primary conductor BU is arranged so as to extend in the horizontal direction in the usage environment, the current sensor 100 of the present embodiment is in a state where the primary conductor BU is inserted in the insertion portion 108 in the horizontal direction. Can be used.

That is, the insertion portion 108 surrounded by the square tube portion 102b is suitable for inserting the primary conductor BU having a square rod shape, and in the insertion state of the primary conductor BU, one surface (inner surface) of the square tube portion 102b is formed. It faces the upper surface of the primary conductor BU. Further, both side surfaces and the bottom surface of the primary conductor BU face the inner surfaces and bottom surfaces of both sides of the square tube portion 102b, respectively. The insertion portion 108 has an inner width dimension wider than the width dimension of the primary conductor BU to be inserted, and has a height larger than the thickness of the primary conductor BU.

[Details of fastening part]
The fastening portion 102f is formed so as to project from the insertion portion 108 in the insertion direction of the primary conductor BU as described above, and has, for example, a structure just like a balcony protruding from the wall surface of the building. That is, the fastening portion 102f has a structure having a bottom plate portion (unsigned) protruding from the outer surface of the case body 102 (back wall portion 102e) and a side plate portion (unsigned) rising from the periphery of the bottom plate portion. .. The side plate portion is connected to the outer surface of the case body 102 (back wall portion 102e) to increase the bending rigidity of the fastening portion 102f.

[Fixing with primary conductor]
In the fastening portion 102f, a total of three through holes 102h and 102k are formed in the bottom plate portion, of which one through hole 102h is a round hole and the other two through holes 102k are elongated holes. In this example, the case body 102 (or the entire current sensor 100) can be fastened to the primary conductor BU by inserting the screw BT into one through hole 102h from above. A screw hole is formed in advance at the corresponding position of the primary conductor BU.

Here, as shown in FIG. 3B, ribs 112 are formed on the lower inner surface of the square tube portion 102b and the lower surface of the fastening portion 102f so as to project from these surfaces. In the fastened state, the lower inner surface of the square tube portion 102b and the lower surface of the fastening portion 102f are not in direct contact with the primary conductor BU (upper surface), but the case body 102 is in contact with the primary conductor BU by the rib 112. It has become. For example, assuming that the case body 102 (the entire current sensor 100) is fixed in a vertical standing position on the horizontal installation surface SF, such a rib 112 is in a state of being fastened to the case body 102 (fastening portion 102f). By holding the primary conductor BU horizontally, the heights H1 and H2 from the installation surface SF to the upper surface of the primary conductor BU are kept the same before and after the insertion direction. Hereinafter, the rib 112 will be further described.

[Straw body]
FIG. 4 is a perspective view showing the current sensor 100 from an obliquely downward direction. Of these, FIG. 4 (A) is a view shown from the back wall portion 102e side, and FIG. 4 (B) is a view shown from the opposite side.

As shown in FIGS. 4A and 4B, the ribs 112 are formed in a plurality of ribs (here, 6 ribs) at intervals in the width direction of the insertion portion 108. As described above, each rib 112 protrudes from the lower inner surface of the square tube portion 102b and the lower surface of the fastening portion 102f, and extends linearly (streak-like) in the insertion direction. Assuming that one end of the rib 112 is the opening end side of the accommodating portion 102d ((B) in FIG. 4) and the other end is the side with the fastening portion 102f ((A) in FIG. 4), one end and the other end of the rib 112 The protrusion height at one end is lower and the protrusion height at the other end is higher. Also, some (two) of the ribs 112 are shorter than others. That is, each rib 112 has an elongated trapezoidal shape when viewed from the side. This is because the other ends of the two ribs 112, which are shorter than the others, are formed only up to the edge of the through hole 102k, which is due to the resin molding (mold production) of the case body 102 including the ribs 112. It depends on the convenience.

[Maintaining position by rib]
FIG. 5 is a diagram showing the holding of the position of the primary conductor BU by the rib 112. Of these, FIG. 5 (A) is a side view, and FIG. 5 (B) is an enlarged view of the vicinity of the fastening portion 102f.

In FIG. 5 (A): When the current sensor 100 is installed in a vertical standing position on the horizontal installation surface SF as described above, the rib 112 is horizontal with respect to the vertical current sensor 100. The primary conductor BU is held at a position (angle). Such holding is realized by the rib 112 being entirely in contact with the upper surface of the primary conductor BU in a state where the primary conductor BU is fastened at the fastening portion 102f.

In FIG. 5 (B): The rib 112 is more easily understood by the enlarged view. The rib 112 has a slightly protruding height D when viewed from the entire case body 102 (current sensor 100), but at a position where the primary conductor BU is separated from the lower inner surface of the square tube portion 102b and the lower surface of the fastening portion 102f. It holds it securely and holds the primary conductor BU in the horizontal position. Further, the primary conductor BU is prevented from coming into surface contact with the lower inner surface of the square tube portion 102b and the lower surface of the fastening portion 102f, and is substantially in line contact only with the lower surface of the rib 112. As a result, an air layer (insulated air layer) is formed between the lower inner surface of the square tube portion 102b and the lower surface of the fastening portion 102f and the upper surface of the primary conductor BU. It can be made difficult to be transmitted to the inside of 100.

[Draft]
FIG. 6 is a vertical cross-sectional view of the case body 102. Here, the case body 102 is shown alone.

As described above, in the completed state of the case body 102, a draft exists (remains) in the square tube portion 102b due to the convenience of resin molding. This means that the inner surface of the square tube portion 102b is formed with an inclination of an angle θ in the vertical direction with respect to the central axis CL defined in advance in the insertion portion 108. Therefore, the lower surface of the fastening portion 102f and connected to the inner surface of the square cylinder portion 102b is also inclined by an angle θ / 2 with respect to the central axis CL.

If the position of the primary conductor BU is to be maintained with reference to the lower inner surface of the inclined square tube portion 102b and the lower surface of the fastening portion 102f, the primary conductor BU will inevitably be inclined by the draft. Therefore, it becomes inconsistent with the horizontal installation surface SF. Alternatively, since the case body 102 (the entire current sensor 100) may be distorted by fastening due to the rigidity of the primary conductor BU, it cannot be said that the case body 102 (the entire current sensor 100) is held at a preferable position in any case.

In the present embodiment, when the rib 112 protruding from the lower inner surface of the square tube portion 102b and the lower surface of the fastening portion 102f is formed on the case body 102 and the primary conductor BU is fastened in contact with the rib 112, the primary conductor BU is first-ordered. The conductor BU is held in a horizontal position. As a result, when the current sensor 100 is installed in a standing posture perpendicular to the horizontal installation surface SF, the positional relationship with the current sensor 100 can be maintained as desired, and the position (posture, angle) of the primary conductor BU can be changed. It can be aligned with the installation surface SF.

[Another form]
FIG. 7 is a perspective view showing another embodiment of the current sensor 100 in which the length of the square tube portion 102b is shortened. This alternative embodiment is the same as that of the above embodiment except that the length of the square tube portion 102b seen in the insertion direction of the primary conductor BU is shortened, and the same effect can be achieved. Since the rib 112 has a trapezoidal shape when viewed from the side, the protruding height (corresponding to the side of the trapezoid) at one end of the rib 112 is reduced by the length of the square tube portion 102b (insertion portion 108). It is also shown in FIG. 7 as being higher than the embodiment.

[Characteristic improvement by rib]
FIG. 8 is a diagram showing that the primary conductor BU is separated from the internal configuration of the current sensor 100 according to the protrusion height DR of the rib 112. Here, it is assumed that the internal configuration (magnetic material core 104, circuit board 106, etc.) of the current sensor 100 is sealed with a sealing resin.

[Capacitive coupling]
When the case body 102 (current sensor 100) and the primary conductor BU are fastened, the physical distance between the primary conductor BU and the internal configuration of the current sensor 100 is inevitably close. At this time, the internal configuration of the primary conductor BU and the current sensor 100 can be capacitively coupled by the parasitic capacitance (stray capacitance) CP. In such a capacitive coupling, the noise of the steep voltage fluctuation (dV / dt) generated in the primary conductor BU invades the output circuit of the internal configuration and the like, and adversely affects the output signal.

〔Thermal resistance〕
Further, when the current sensor 100 is used, a large current (for example, several hundred to several thousand A) is energized in the primary conductor BU, so that the amount of heat generated by the primary conductor BU itself is large. At this time, there is a thermal resistance HR due to physical contact or an intermediary (air) between the primary conductor BU and the current sensor 100. Therefore, heat is transferred from the primary conductor BU to the current sensor 100, the temperature of the magnetic core 104, the Hall element 110, the output circuit, and the like rises, and the output signal fluctuates.

The inventors of the present invention have verified the influence of the above-mentioned dV / dt noise and the influence of heat transfer on the output signal, and have verified the protrusion height, the number of ribs 112, and the length in the insertion direction of the ribs 112 in contact with the primary conductor BU. It was confirmed that the adverse effect was suppressed when all of them were small (low protrusion height, small number, short length). Hereinafter, the verification results will be described.

[Verification of dV / dt characteristics]
9 and 10 are diagrams showing the results of observing the dV / dt characteristics of the current sensor 100. Here, the "dV / dt characteristic" is an index for measuring how much the output signal (waveform) of the current sensor 100 is affected by the voltage fluctuation (dV / dt) generated in the primary conductor BU, and is a voltage fluctuation. It is considered that the lower the influence on the output signal received from is, the better the dV / dt characteristic is exhibited.

[Rib protrusion height 0]
First, in FIG. 9, it is assumed that the protrusion height DR of the rib 112 is 0, that is, the primary conductor BU is not brought into contact with the rib 112, but the primary conductor BU is brought into contact with the lower inner surface of the square tube portion 102b and the lower surface of the fastening portion 102f. The result of observing the dV / dt characteristic of the case is shown.

In FIG. 9 (A): In order to observe the dV / dt characteristics, a waveform in which the voltage drops stepwise at a certain time t1 is applied to the primary conductor BU, and a waveform in which the voltage rises stepwise at time t2 is applied to the primary conductor BU. Applied.
FIG. 9B: Observation result of the output waveform with respect to the applied waveform. Extreme changes (malfunctions) were observed in the output waveforms at time t1 and time t2, when the applied waveform stepped up and down. The maximum amount of malfunction Vp-p1 of these output waveforms was, for example, about 350 mV.

[Large rib protrusion height]
Next, in FIG. 10, the protrusion height DR of the rib 112 is set to a large value (for example, 4.5 mm), and the primary conductor BU is brought into contact with the rib 112 so that the lower inner surface of the square tube portion 102b and the lower surface of the fastening portion 102f can be seen. The dV / dt characteristics when the distance to the primary conductor BU is separated are shown.

In FIG. 10 (A): Similarly to the above, a waveform in which the voltage drops stepwise at time t1 is applied to the primary conductor BU, and a waveform in which the voltage rises stepwise at time t2 is applied to the primary conductor BU.
In FIG. 10 (B): At time t1 and time t2, when the applied waveform stepped up and down, minute changes (malfunctions) in the output waveform were observed. The maximum amount of malfunction Vp-p2 of these output waveforms was, for example, about 300 mV.

[Relationship between distance and amount of malfunction]
FIG. 11 shows the relationship between the distance from the lower inner surface of the square tube portion 102b and the lower surface of the fastening portion 102f to the upper surface of the primary conductor BU (protruding height DR of the rib 112) and the malfunction amount Vp−p appearing in the output waveform. It is a figure. Although the illustration of the waveform observation result is omitted, the inventors of the present invention have set the protrusion height DR to be small (for example, 1.5 mm) and medium (for example, 3.0 mm). The output waveforms of Vp-p are also observed and summarized in the relationship diagram of FIG. 11 (Vp-p is a general term including observation results of Vp-p1, Vp-p2, etc.).

From the above observation results, the following is clear.
That is, when the primary conductor BU is brought into contact with the rib 112 to separate the distance from the lower inner surface of the square tube portion 102b and the lower surface of the fastening portion 102f, the dV / dt characteristics are greatly improved as compared with the case where the primary conductor BU is not brought into contact with the rib 112. Has been done. Then, it can be seen that when the protruding height DR of the rib 112 is increased, the dV / dt characteristics are improved accordingly. This means a significant effect due to the reduced capacitive coupling between the primary conductor BU and the various components of the current sensor 100 by increasing the distance.

[Effect of heat]
In addition, the inventors of the present invention have summarized the verification results regarding the protrusion height DR of the rib 112, the number of contacts, the width and the length of the rib 112 below.

That is, in the present embodiment, by bringing the rib 112 into contact with the primary conductor BU in the fastened state, the distance between the primary conductor BU and the internal circuit configuration can be increased, and the contact area between the case body 102 resin and the primary conductor BU can be increased. It can be reduced and the thermal resistance HR can be lowered. At this time, the larger the protrusion height DR of the rib 112, the smaller the number of contacts, the narrower the width of the rib 112, and the shorter the length, the lower the thermal resistance HR and the less the thermal effect. it can.

〔Reference value〕
For the above-mentioned effect of improving the dV / dt characteristics and the effect of reducing the heat effect, for example, the numerical values shown in the following table can be referred to.

[Other verification results]
FIG. 12 is a diagram showing an evaluation model of dV / dt characteristics obtained by changing the positional relationship between the primary conductor BU and the current sensor 100 from the arrangement of FIG. Since the rib 112 is not related to this positional relationship, the distance DS is used here for evaluation. It should be noted that the reason why the verification is performed in the horizontal arrangement of the current sensor 100 as shown in FIG. 12 is that the circuit board 106 is arranged in a U shape (horizontal direction) as shown in FIGS. 1 and 2. This is to evaluate the relationship between the central portion of the above and the distance DS between the primary conductor BU.

[Verification of dV / dt characteristics]
13 and 14 are diagrams showing the results of observing the dV / dt characteristics of the current sensor 100 in the evaluation model of FIG.

[Distance DS = 0]
First, FIG. 13 shows the results of observing the dV / dt characteristics when the distance DS is 0, that is, when the primary conductor BU is brought into contact with the inner surface of the square tube portion 102b.

In FIG. 13 (A): In order to observe the dV / dt characteristics, a waveform in which the voltage drops stepwise at a certain time t1 is applied to the primary conductor BU, and a waveform in which the voltage rises stepwise at time t2 is applied to the primary conductor BU. Applied.
FIG. 13 (B): Observation result of the output waveform with respect to the applied waveform. Extreme changes in the output waveform (malfunction) were observed at time t1 and time t2, when the applied waveform stepped up and down. The maximum amount of malfunction Vp-p3 of these output waveforms was, for example, about 512 mV.

[Distance DS = Large]
Next, FIG. 14 shows the dV / dt characteristics when the distance DS is large (for example, 4.5 mm) and the primary conductor BU is greatly separated from the inner surface of the square tube portion 102b.

In FIG. 14 (A): Similarly to the above, a waveform in which the voltage drops stepwise at time t1 is applied to the primary conductor BU, and a waveform in which the voltage rises stepwise at time t2 is applied to the primary conductor BU.
In FIG. 10 (B): At time t1 and time t2, when the applied waveform stepped up and down, minute changes (malfunctions) in the output waveform were observed. The maximum amount of malfunction Vp-p4 of these output waveforms was, for example, about 228 mV.

[Relationship between distance and amount of malfunction]
FIG. 15 is a diagram showing the relationship between the distance DS and the amount of malfunction Vp−p appearing in the output waveform. Although the illustration of the waveform observation result is omitted here as well, the inventors of the present invention have other than this, the output when the distance DS is set to small (for example, 1.5 mm) and medium (for example, 3.0 mm). Waveforms were also observed and these are summarized in the relationship diagram of FIG. 15 (Vp-p is a general term including observation results of Vp-p3, Vp-p4, etc.).

From the above observation results, the following is clear.
That is, when a large distance DS is secured, the dV / dt characteristics are greatly improved as compared with the case where the distance DS is 0. Then, it can be seen that when the distance DS is increased, the dV / dt characteristics are improved accordingly. This means a remarkable effect due to the reduction of the capacitive coupling between the primary conductor BU and the various components of the current sensor 100 by increasing the distance as before. Therefore, for example, when the current sensor 100 is arranged sideways with respect to the horizontal primary conductor BU as shown in FIG. 12, the fastening portion 102f and the rib 112 are arranged so as to face the upper surface of the primary conductor BU. By molding the body 102, it is possible to stabilize the primary conductor BU, improve the dV / dt characteristics, and reduce the heat effect.

As described above, according to the current sensor 100 of the present embodiment, the following advantages can be largely obtained.
(1) By fastening the case body 102 to the primary conductor BU at the fastening portion 102f, the primary conductor BU can be stabilized in the used state.
(2) Even when the square tube portion 102b or the like of the case body 102 is provided with a draft, the relative positional relationship between the case body 102 (the entire current sensor 100) and the primary conductor BU can be determined by contact with the rib 112. It can be kept constant (horizontal state).
(3) By contacting the primary conductor BU with the rib 112, the capacitive coupling and thermal resistance between the primary conductor BU and the internal circuit or the like can be reduced, the dV / dt characteristics can be improved, and the thermal effect can be reduced.

The present invention can be implemented in various modifications without being limited to the above-described embodiment.
The shape of the insertion portion 108 is not limited to a square cylinder shape, but may be a cylindrical shape. In this case, the rib 112 is formed so as to project from the inner surface of the cylindrical insertion portion 108. Further, the primary conductor BU may be in the shape of a round bar or in the shape of a square bar. In any case, the rib 112 may be formed according to the outer shape of the primary conductor BU.

The protruding height, number, length, width (thickness), and the like of the ribs 112 mentioned in one embodiment are all examples, and may be changed as appropriate.

In addition, the structures shown in the drawings in the embodiments and the like are merely preferable examples, and it is said that the present invention can be preferably carried out even if various elements are added to the basic structure or a part thereof is replaced. Not to mention.

100 Current sensor 102 Case body 104 Magnetic material core 106 Circuit board 108 Insertion part 110 Hall element 112 Rib

Claims (5)

In a current detector that performs detection with a conductor through which the current to be detected flows inserted,
A main body that accommodates the device for detection and has an insertion portion that partitions the periphery of the conductor to be inserted by a surface extending in the insertion direction.
A ridge body that is formed so as to project from the surface of the insertion portion and that maintains a relative positional relationship between the main body and the conductor by fastening the main body to the conductor in a state of being in contact with the conductor. Equipped with a current detector. In the current detector according to claim 1,
The insertion part is
It has a square tubular shape that extends in the insertion direction of the conductor and surrounds the conductor with surfaces from four directions.
The main body
It has a surface that is formed so as to project from the insertion portion in the insertion direction of the conductor and extends continuously to one surface of the insertion portion, and the main body and the conductor are fastened with this surface facing the conductor. Has a fastening part that enables
The ridge body
A current detector characterized in that it is formed so as to project from a continuous surface of the insertion portion and the fastening portion facing the conductor. In the current detector according to claim 1 or 2.
The ridge body
When the outer surface of the conductor has a plane extending in the insertion direction, the current detection is characterized in that the plane of the conductor is held parallel to the axis defined in advance in the insertion portion in a state of being in contact with the conductor. vessel. In the current detector according to claim 3,
A current detector characterized in that the surface of the insertion portion facing the plane of the conductor forms an angle with the plane of the conductor. In the current detector according to any one of claims 1 to 4,
The ridge body
By ensuring a large distance from the conductor inserted through the insertion portion to the device accommodated in the main body according to the height of protrusion from the surface of the insertion portion, the voltage change of the detected current can be changed. A current detector characterized by reducing the influence on a change in an output signal from the device.

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