JPS6314426Y2 - - Google Patents

Description

[Detailed description of the invention] [Purpose of the invention] (Field of industrial application) The present invention relates to a current transformer that combines a magnetic circuit, a semiconductor magneto-sensitive element, and a control power supply. The present invention relates to a current transformer using a substrate unit in which a Hall element can be easily and reliably inserted into a gap in a magnetic circuit.

(Prior Art) In general, a current transformer using a semiconductor magnetic sensing element, such as a Hall element, has a core 1 made of an iron core with a gap 2 to form a magnetic circuit including the gap 2, as shown in FIG. A semiconductor magnetic sensing element, such as a Hall element 3, is inserted into the gap 2 of the core 1, and a control power source 4 is provided for flowing a control current I _C through the Hall element 3, and further a current to be measured I ₁ is caused to flow therethrough. The conductor 5 is formed by penetrating the core 1.

Further, the operating principle of the current transformer configured as described above is as follows.

That is, when a current I ₁ flows through the conductor 5, the current I ₁
A magnetic flux Φ proportional to Φ passes through the core 1. This magnetic flux Φ
passes through the Hall element 3 within the air gap 2. At this time, if the control current I _C flowing through the Hall element 3 is kept constant, a Hall voltage V _H proportional to the magnetic flux Φ passing through the air gap 2 is extracted from the Hall element 3 as an output. In other words, the conversion from current I ₁ to magnetic flux Φ, and magnetic flux Φ
A Hall voltage V _H proportional to the current I ₁ can be obtained by converting from V H to a Hall voltage V _H (control current I _C is constant). Therefore, the current I ₁ can be measured from the magnitude of the Hall voltage V _H.

In FIG. 5, a plurality of, for example, four, air gaps are provided in the core 1, one Hall element 3 is inserted into each air gap 2, and each Hall voltage V _H output from each Hall element 3 is collected by a summing amplifier 6. This figure shows a current transformer configured to add. According to such a current transformer, the Hall voltage V _H taken out can be increased, and the influence of external magnetic flux can be avoided.

(Problems to be Solved by the Invention) Now, in the current transformer configured as described above, considering the total spacing g of all the voids in the core, the spacing g is given by the following equation.

g=μ _p・μ _g・I ₁ /Bm ...(1) However, I ₁ is the current to be measured, μ _p is the magnetic permeability of air, μ _g
is the relative magnetic permeability of the air gap, Bm is the maximum value of I ₁ ,
This is the required magnetic flux density of the air gap that is most suitable for the output of the Hall element.

From the above equation (1), since Bm is determined by the Hall element and _μg is determined by the structure of the core, g can be considered to be approximately proportional to I ₁ .

However, current transformers using Hall elements were originally developed to overcome the problems of current shunts and magnetic amplifiers, such as difficulty in measuring in the large current range, large structures, and economic disadvantages. It is something that Therefore, it is inevitably used in a large current range, and the actual situation is that g is relatively large accordingly.

On the other hand, the most common Hall element is one in which a Hall element element 11 is adhered to a small piece of ceramic and the required wiring 13 is provided, as shown in FIG. As shown in Fig. 7, this Hall element is
It is common practice to embed the spacing piece 14 at an appropriate location corresponding to the spacing g, and to insert this spacing piece 14 into the gap 2 of the core 1.

However, in recent years, DC power supplies have become more precisely controlled and protected, and current transformers using Hall elements have good responsiveness to changes in measured current and can distinguish between positive and negative current polarities. The measurement accuracy is good, and the measurement current circuit and output circuit are insulated, which is why it is being reconsidered. In addition, there is a strong demand for current transformers that use Hall elements to be used in small current ranges, which have been disadvantageous due to their characteristics, and for those that have a large number of air gaps as shown in Figure 5 due to their characteristics. This is becoming more and more common. This inevitably requires the gap g to be made very narrow, and as a result, it becomes difficult to insert and fix the Hall element as a single unit into the gap in the core as shown in FIG. ing. Further, if spacing pieces are used as shown in FIG. 7, it becomes difficult to accommodate narrow g spacings. Therefore, there is a problem that it is not possible to obtain a current transformer with good characteristics in a small current range.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide a current transformer using a substrate unit that allows Hall elements to be inserted easily and reliably into very narrow gaps.

[Structure of the idea]

(Means and effects for solving the problems) In order to achieve the above-mentioned objects, the present invention includes a core portion having a gap and forming a magnetic circuit, a semiconductor magnetic sensing element portion inserted into the gap, and a core portion having a gap and forming a magnetic circuit. In a current transformer comprising a control power supply that supplies a control current to a semiconductor magnetically sensitive element section, the semiconductor magnetically sensitive element section is attached to a board unit in which the semiconductor magnetically sensitive element is mounted and wired on an insulating substrate on which lead wiring is printed in advance. Accordingly, the present invention is characterized in that an induced electromotive force compensation circuit is formed on this substrate unit by printed wiring.

(Embodiments) The present invention will be described below with reference to embodiments shown in the drawings.

FIG. 1 shows an embodiment of a board unit used in the current transformer of the present invention.

In the figure, reference numeral 11 denotes a Hall element element, and 12 denotes a thin insulating substrate (12) that serves as a small piece necessary for adhesively fixing the Hall element element 11 and as a substrate for reliably setting the Hall element element 11 in a narrow gap. For example, a ceramic substrate).

On this insulating substrate 12, wiring for passing a control current through the Hall element body 11 and an output line for taking out the Hall voltage _VH are formed by printed wiring.
In this substrate unit, the thickness of the Hall element element, the thickness of the printed wiring, and the thickness of the insulating film covering their surfaces are very thin, and if the insulating substrate 12 has enough strength to be inserted into the gap, then the whole The thickness can be made, for example, 1 mm or less. Therefore, an extremely thin substrate unit can be obtained.

Further, a circuit 16 for exactly compensating the induced electromotive force of the circuit for taking out the Hall voltage _VH of the substrate unit is formed by printed wiring, and is connected in series with the terminal where the Hall voltage _VH is generated.

Note that the connection between the board unit and the external wiring 13 is made at the end of the printed wiring.

FIGS. 2 and 3 each show a specific embodiment of the present invention.

These embodiments have basically the same construction as that shown in FIG.

Figure 2 shows the Hall voltage V _H of the printed wiring.
Loop 1 is made by wiring a one-inch wire so as to overlap in the direction of the magnetic flux in a multi-layered manner so as to make the induced electromotive force as low as possible, and furthermore to compensate for the electromotive force that causes loop 16 at the end of the wiring.
7 is shown.

Figure 3 shows a board unit in which printed wiring is provided on the front and back of the board, sufficiently overlapping in the direction of magnetic flux, and these printed wirings are connected by through holes 18, thereby eliminating any induced electromotive force. This is what is shown.

[Effect of idea]

As described above, according to the present invention, a very thin substrate unit can be used in a current transformer using a Hall element, which has been in high demand in recent years.
It has the advantage of being able to be used for small currents or of a multi-element type that minimizes the influence of external magnetic fields and improves characteristics.

In addition, since printed wiring is used for wiring,
Miswiring can be prevented, and a circuit that compensates for the induced electromotive force in the wiring circuit can be provided accurately as calculated. Furthermore, wiring can be performed so that no induced electromotive force is generated, and a current transformer with good response characteristics that is faithful to the current to be measured can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a basic substrate unit according to the present invention, FIG. 2 and FIG. 3 are perspective views of substrate units showing other embodiments of the present invention, and FIG. 4 is a basic configuration diagram of a current transformer using a semiconductor magnetic sensing element.
FIG. 5 is a diagram showing the configuration of a current transformer using a plurality of semiconductor magnetic sensing elements, and FIG. 6 is a basic diagram showing the configuration of a Hall element.
FIG. 7 is a perspective view of a conventional substrate unit. 1: core; 2: gap; 3: Hall element;
4: control power supply, 5: conductor, 6: summing amplifier, 11: Hall element body, 12: substrate, 1
3: lead-out wiring; 14: spacer; 15: printed wiring; 18: through hole.

Claims (1)

[Claims for Utility Model Registration] (1) A semiconductor magneto-sensitive element section inserted into the gap of a core section that has an air gap and forms a magnetic circuit, and a control power source that supplies a control current to the semiconductor magneto-sensitive element section. In the current transformer comprising: At least one pair of the lead wires are
A current transformer characterized in that an induced electromotive force compensation circuit is formed by overlapping multilayer printed wiring in an insulated state with respect to the direction of magnetic flux passing by the current to be measured. (2) In claim 1 of the utility model registration claim, at least one pair of lead-out wirings formed on the board unit has one wiring routed around the surface of the board via a through-hole, and the wiring and one other wiring on the surface thereof are formed so as to have sufficient overlap in the direction of magnetic flux passing by the current to be measured.