JPS61225661A - Current sensor - Google Patents

Abstract

PURPOSE:To achieve a higher sensitivity, by burying a magnetoelectric transducer element into a magnetic body forming a magnetic path. CONSTITUTION:A Hall element chip 6 is molded with a resin or the like to be insulated from a core 5. The Hall element chip 6 is buried into the core 5 in the form of powder at the stage where the core 5 is being molded from powdered magnetic material and solidified with the powdered magnetic material during the firing thereof. In such a manner, the Hall element chip 6 is buried into the core 5, thereby eliminating exposed portion of the Hall element chip 6 defining the gap length and hence the gap length can be reduced to the limit in the manufacture of the core 5 or in the combined growth of the core 5 molding material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a current sensor that detects current using a magnetoelectric conversion element.

[Conventional technology]

The second (iU) is a configuration diagram of a current sensor using a conventional Hall element as a magnetoelectric conversion element, for example, described in catalog RHB203, P1 to P8J published by Siemens Electronic Components Group of Japan.

Figure 2 a is a configuration diagram of a current sensor using a Hall element that has been used conventionally. The iron core is a magnetic material that forms a closed magnetic path through which the magnetic flux φ due to the magnetic field passes, (3) is a Hall element chip that detects the magnetic flux φ and generates a voltage, and (4) is the Hall element chip [3] connected to the iron core (2). This is a ceramic board for fixing to the board and wiring lead wires. The Hall element chip (3) on the ceramic substrate (4) is attached to the iron core (2) as shown in Figure 2.
It is installed in a gap G having a length ig and a cross-sectional area S.

Next, the principle of voltage generation will be explained based on the installation state of the Hall element E.

When the current to be measured I flows through the coil (1) wound around the iron core (2), a magnetic flux φ is generated in the iron core (2) due to the magnetic field generated in the coil (1). The magnetic flux passes through a closed magnetic path and reaches the gap G of the iron core (2) at a magnetic flux density B.
generates a magnetic field. As shown in Figure 2C, this magnetic field is applied perpendicularly to the surface of the Hall element (3) installed in the gap G. At this time, the Hall element (3) is controlled in one direction perpendicular to the magnetic field. Since the current 11 is acting at the same time, the output voltage v2 is generated in the directions (4a) and (4b) perpendicular to the magnetic field B and the control current i4.

The output voltage v2 is expressed by the following relationship, where Rh is the Hall constant, d is the thickness of the Hall element, and B is the magnetic flux density at the gap G.

In this case, as a method to increase the sensitivity of the sensor, that is, the output voltage v2, it is possible to flow more control current i1 or to increase the magnetic flux density B, but the former method depends on the allowable control current of the Hall element itself. Since there is a limit, it is best to increase the value of magnetic flux density B.

The relationship between the magnetic flux density B and the length intersection g of the gap G is expressed by the following two equations.

2g: Magnetic resistance of K, S: Cross-sectional area of gear, ρ: Magnetic resistance per unit volume of gap.

Zc: Magnetic resistance of iron core, N: Number of turns of coil, ■= Current to be measured, Φ: ? As is clear from equations (2) and (3) for a-flux H, the magnetic flux density B can be increased by reducing the length Ig of the gap G. Thereby, it becomes possible to increase the output voltage v2 as shown in equation (1).

[Problem that the invention seeks to solve]

However, in conventional current sensors, the range in which the length of the gap G can be reduced is limited by the thickness of the Hall element chip or the ceramic substrate, and as a result, the magnitude of the magnetic density is limited by the magnetic resistance. There was a limit to the improvement of sensitivity.

This invention was made to solve the above-mentioned problems, and it reduces the gap, which is the magnetic resistance component of the closed magnetic circuit, to the limit, provides a larger magnetic flux density to the Hall element, and provides a highly sensitive current sensor. The purpose is to

[Means for solving problems]

The current sensor according to the present invention has a magnetoelectric conversion element embedded in a magnetic material.

[Effect]

According to this invention, the gap length can be reduced to the limit by burying the magnetoelectric transducer in a magnetic material with no exposed parts, and as a result, the Tj1 resistance of the closed magnetic circuit can be reduced and the magnetic flux density can be increased. This improves the sensitivity of the current sensor.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

In Fig. 1, (5) is an iron core made of fired magnetic powder;
(6) is a Hall element Qi embedded in the iron core (5).

It is a pool. The Hall element chip (6) is molded with resin or the like and is insulated from the iron core (5).

The Hall element chip (6) is embedded in the powdered iron core when the iron core (5) is molded from the powdered magnetic material, and is solidified together with the powdered magnetic material during firing.

As described below, the Hall element chip (6) can be embedded in the iron core (5), so there is no exposed part of the Hall element chip (6) that limits the gap length in the gap in the iron core (5). . Therefore, the gap length can be reduced to the limit due to the machining of the core, E or the composition of the material for forming the core.

Reducing the gap length means that the magnetic resistance Rg of the gap decreases, as is clear from equation (2). As a result of the decrease in magnetic resistance Rg, as can be seen from equation (3), the magnetic flux distribution 1 gB applied to the Hall element increases, and a larger output voltage v2 can be extracted based on a constant control current 11 flowing through the Hall element. This means that the sensitivity of the current sensor is improved.

〔Effect of the invention〕

Hereinafter, according to the present invention, as shown in H, since the magnetoelectric conversion element is embedded in the magnetic material forming the magnetic path, the air gap associated with the installation of the magnetoelectric conversion element can be reduced compared to the magnetic material, As a result, the magnetoresistance component is reduced compared to the magnetic plug body, and more magnetic flux density is applied to the magnetoelectric conversion element, thereby providing a highly sensitive current sensor capable of producing a large voltage output.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the current sensor of the present invention,
FIG. 2 is a configuration diagram showing a conventional current sensor. (1): Coil, (2): Magnetic material, (3): Magnetoelectric conversion element, (4): Ceramic substrate, (5) Two magnetic materials according to the present invention, (6): Embeddable Hall element. Agent Masuo Oiwa Figure 1 Figure 1: Coil Figure 2 (a) (b) (C) Procedural amendment (voluntary) Showa year, month, day

Claims (1)

[Claims] A current sensor comprising: a magnetic body forming a closed magnetic path through which a magnetic flux generated by a coil through which a current to be measured passes; and a magnetoelectric conversion element that detects the magnetic flux passing through the closed magnetic path and performs magnetoelectric conversion; A current sensor characterized in that the magnetic resistance of a closed magnetic circuit is reduced by embedding in a magnetic body.