JPH03170873A - Current detector - Google Patents

Abstract

PURPOSE:To obtain a detector having both of the high sensitivity characteristic within a small current range requiring resolving power and a wide current detection range for a large current range by constituting a core by inserting other ferromagnetic material different in saturated magnetic flux density in the central part of a ferromagnetic core in series. CONSTITUTION:A through-type electric wire 5 allowing a current to be measured to flow is allowed to pierce through a ferromagnetic core 3. The magnetic flux generated by the current of the electric wire 5 is converged by the core 3 to generate magnetic flux in the space of the magnetic gap 1 of the core 3 and the intensity of the magnetic flux is measured by a magnetism-sensitive element 2. A thin plate-shaped ferromagnetic material B4 low in saturated magnetic flux density is inserted in the central part of the core 3 formed of a ferromagnetic material A high in saturated magnetic flux density and a core is constituted by the series connection of two or more kinds of magnetic materials. A current detector using the core thus constituted has two-step sensitivities across a point where the part of the ferromagnetic material B4 is saturated. That is, a detection current range can be extended by keeping conventional sensitivity within a small current range requiring resolving power and lowering sensitivity within a large current range.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is applicable to electric appliances used in electronic equipment or electric machinery, etc.
．． ．． The present invention relates to a detector, and in particular to the configuration of a ferromagnetic core of a current detector in which a gap is provided in a part of a toroidal ferromagnetic core and a magnetic sensing element is configured within the gap.

[Prior Art] Conventionally, in this type of current detector (Fig. 2), the ferromagnetic core 3 used in the part forming the magnetic circuit has a ferromagnetic core 3 in particular in order to widen the detection current range. A ferromagnetic material A with a high saturation magnetic flux density or a ferromagnetic material B with a low coercive force is used to reduce the detection difference, and the magnetic material into which a magnetically sensitive element 2 such as a Hall element or a magnetoresistive element is inserted is used. A gap 1 is formed, and a magnetic sensing element 2 is placed in the magnetic gap 1.
An output voltage proportional to the magnitude of the current is obtained by the magnetic sensing element 2 inserted into the magnetic gap 1 which generates a magnetic field proportional to the current to be measured flowing through the through wire 5.

The output voltage proportional to the current in the through wire 5 detected by the magnetic sensing element 2 is amplified by a signal amplification circuit to obtain an output voltage proportional to the magnitude of the current, thereby detecting the magnitude of the through current.

Problem to be solved by the invention C] However, in conventional current detectors, the saturation magnetic flux density of the ferromagnetic core used in the part that forms the magnetic circuit directly affects the detection current range; The design was limited to 6 degrees and the detection current range to one target depending on the saturation magnetic flux density of the ferromagnetic material and the shape of the core. Therefore, if the magnetic gap is made small in order to obtain high sensitivity in a small current range where resolution is required (1), the ferromagnetic core tends to become saturated, making it impossible to obtain a sufficient current detection range. Furthermore, if the magnetic gap is increased to increase linearity in the large current range, the output in the small current range is small, so separate current detectors are required for large current detection and small current detection.

[Means for solving the problem] According to the present invention. In order to eliminate this conventional drawback, a gap is provided in a part of the magnetic path of the toroidal ferromagnetic core, and a magnetic sensing element is inserted into the gap. The core is constructed by connecting two or more types of ferromagnetic materials in series by inserting other ferromagnetic materials with different saturation magnetic flux densities in series in the central part of the core, and is characterized by having a sensitivity of two or more orders of magnitude. A current detector is obtained.

[Tamaki's fM construction] In the ferromagnetic core of a current detector in which a gap is provided in a part of the magnetic path of the toroidal-shaped ferromagnetic core and a magnetic sensing element is carefully constructed within the gap, the ILJ As shown in the figure, a toroidal ferromagnetic core 3 made of a ferromagnetic material A with a high saturation magnetic flux density has a magnetic material B with a low saturation magnetic flux density in the center of the core. ``The core is composed of two or more magnetic materials connected in series.

[Function] In a current detector using a core configured as shown in Fig. 1, the sensitivity until the ferromagnetic material B reaches the magnetic saturation point is determined by @gap length L, number of turns of through wire N, detection g, current I. It is proportional to (NI/L). Magnetic g After material B is saturated, no more than 1 magnetic flux passes through the magnetic material B portion, which can be equivalently regarded as a magnetic gap, and the ferromagnetic core operates in the same manner as in Figure 1 (b). do.

Therefore, the sensitivity after the ferromagnetic material B is saturated is (Nl/L
+L2).

g From then on, a linear output can be obtained until the ferromagnetic material A reaches saturation. Furthermore, the saturation point of the magnetic material A is extended due to the equivalent expansion of the magnetic gap, and the range of the detected current detector becomes wider.

[Example] An example will be explained with reference to the drawings. FIG. 2 is a front view of the structure of a conventional current detector. A toroidal ferromagnetic core 3 is passed through a through wire 5 through which a current to be measured flows, and the ferromagnetic core 3 focuses the magnetic flux generated by the current in the through wire 5, and the magnetic gap 1 of the ferromagnetic core 3 is Create a magnetic flux in the space. The strength of the magnetic flux in the magnetic gap 1 is determined by the magnetic sensing element 2 as dPI. This second
The sensitivity of the current detector shown in the figure is proportional to (Nl/L).

g The input/output characteristics when grain-oriented silicon steel is used for the ferromagnetic core shown in FIG. 2 are shown by broken lines in FIG.

FIG. 1 shows an embodiment of the ferromagnetic core structure of the current detector of the present invention. A ferromagnetic core as shown in Figure 1 is constructed using grain-oriented silicon steel, a ferromagnetic material with a high saturation magnetic flux density, as the ferromagnetic material A, and permalloy, a ferromagnetic material with a low saturation magnetic flux density, as the ferromagnetic material B. are doing.

In Figure 3. The solid line indicates the human output characteristic of the current detector using the core of this example. In FIG. 3, up to point P, the permalloy part operates as part of the core, and its sensitivity is proportional to (N.I/L). At point P-L in Figure 3, the permalloy part is saturated and becomes equivalent to the magnetic gap, and the sensitivity of the current detector is (N I/
L + L2). The output g force in this section is also linear. The sensitivity decreased as the magnetic gap increased, so that the detection current range of the current detector made only of silicon steel was A1 in Figure 3, but it was A2 in the current detector of the example. The detection current range is widened.

A current detector using a core configured as shown in Figure 1 has two levels of sensitivity at the point where the permalloy part saturates (inflection point), and this has high sensitivity characteristics in the small current range where resolution is required. It has now become possible to provide a current detector that has a narrow current detection range for large current ranges.

[Effects of the Invention] As described above, the current sensitivity can be linearly expanded by maintaining the conventional sensitivity in the small current range where resolution is required and decreasing the sensitivity in the large current range. Further, the inflection point of the z degree of this current detector and the slope after the inflection point can be arbitrarily set by selecting the type and thickness (L2) of the ferromagnetic material B to be volatilized. This current detector with two levels of sensitivity has the features of a small current detector that requires a high resolution capability and a large current detector that requires a linear output up to large currents, so it By winding the through wire for large current detection and the through wire for small current detection on the outside, one current detector can serve both large current detection and small current detection, which is an industrially useful invention.

[Brief explanation of the drawing]

Fig. 1(a) shows the ferromagnetic core portion of the current detector of the present invention, Fig. 1(b) shows the state in which the ferromagnetic material B of Fig. 1(a) is removed, and Fig. 2 shows the ferromagnetic core part of the current detector of the present invention. FIG. 3 is a front view showing the structure of a commonly used current detector, and a diagram showing the input/output characteristics of the current detector. Note that the solid line represents a current detector using a ferromagnetic core according to an embodiment of the present invention, and the broken line represents a current detector using only grain-oriented silicon steel. DESCRIPTION OF SYMBOLS 1...Magnetic gap, 2...Magnetic sensing element, 3...Ferromagnetic material A (grain-oriented silicon steel), 4...Ferromagnetic material B (permalloy), 5...Through electric wire. 6...Circuit parts, 7
Temporary circuit mounting board, 8...external terminal.

Claims (1)

[Claims] (1) In a ferromagnetic core of a current detector in which a gap is provided in a part of the magnetic path of a toroidal ferromagnetic core and a magnetically sensitive element is inserted into the gap, the center portion of the ferromagnetic core is A current detector characterized in that the core is constructed by connecting two or more types of ferromagnetic materials in series by inserting other ferromagnetic materials with different saturation magnetic flux densities in series, and the current detector has two or more levels of sensitivity.