JPS6023738Y2 - magnetic field detector - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a magnetic field detector that uses a magnetically sensitive element such as a Hall element to measure a magnetic field, or converts a magnetic field into electricity to measure a bus current.

Conventionally, when measuring a magnetic field using a Hall element, emphasis has been placed on compensation for the temperature of the Hall element, residual voltage, etc., and no consideration has been found for changes in magnetic flux in the high frequency region.

Figures 1a and 1b show a plan view and a sectional view of a conventional detector.

Reference numeral 1 denotes a Hall element, which is wrapped in a covering member 2 made of an insulator, and has four lead wires 3 extending radially, two of which are connected to control current terminals 11. I2, and the other two are connected to output voltage terminals V□ and ■2, respectively.

And each terminal V1. V2, 11. (2) Connect external connection lead wires 4 and 5 to 2, respectively.

In such a configuration, when a suddenly changing magnetic field is detected by the Hall element 1, magnetic flux interlinks with the lead wire 3 for output from the Hall element 1 and the lead wire 4 for external connection, and due to the temporal change of this magnetic flux, A voltage is induced in these lead wires 3, 4.

In other words, the above voltage is superimposed on the original magnetic field detected in the form of voltage, making accurate magnetic field measurement impossible.

An object of the present invention is to provide a detector in which the above-mentioned induced voltage is minimized and the influence of the induced voltage is reduced.

An embodiment of the detector of the present invention will be described below with reference to FIGS. 2a and 2b.

That is, the Hall element 1 and its lead wires 3, 4 or 3,
The opening area in the direction of the magnetic flux Φ of 5 is made as small as possible, and the opening area is offset by the wire ring 11 on the opposite side.

The external connection leads 4 or 5 are twisted so that up to the root portion 4a or 5a, they overlap with the lead wire 3 (in Fig. 2a, they are slightly shifted, but they are essentially overlapped). , a wire ring 11 is formed in the middle of the lead wire 4, and the other parts are the same as in FIGS. 1a and 1b.

FIG. 3 shows an example of a magnetic field measuring device using a Hall element.

6 is the iron core, 7 is the air gap, 8 is the measuring device, 9 is the input terminal, 10
is the power supply.

When measuring the magnetic flux Φ of the iron core 6 having this air gap 7, the magnetic flux passing through the air gap 7 is also the same, so by detecting the magnetic field generated by this magnetic flux Φ with the Hall element 1, the characteristics of the Hall element 1 can be determined in advance. That is, it can be easily measured by determining the characteristics of the output voltage with respect to the magnetic field.

As is well known, the Hall element 1 has a control current terminal ■1? By applying a constant current to I2, a voltage proportional to the magnetic flux Φ passing through the Hall element 1 is output to the output voltage terminal V1. ■Induced between the two.

Such an element is inserted into the air gap 7 for measurement, and the output voltage terminal V1. of the Hall element 1 is measured. (1) A lead wire 4 is required to lead the output from the measuring device 2 to the measuring device 8.

Similarly, a lead wire 5 is required for the control current terminal IHI2.

When the input impedance of the measuring device 8 is relatively large, the Hall element 1 and each lead wire 3, 4, or 3.5 form a 1-turn circuit, so magnetic flux will not be linked to this 1-turn circuit. It is easily inferred.

When the waist magnetic flux Φ suddenly changes, the temporal change in magnetic flux dΦ/d
t induces a voltage in this circuit, and the measuring device 8 measures the output voltage of the Hall element 1 and the induced voltage, resulting in an error.

From the above, it is sufficient to reduce the number of interlinked magnetic fluxes by minimizing the area of the circuit forming one turn in the direction in which the magnetic flux Φ passes.

Generally, the external connection lead wires 4 or 5 are made using twisted wires, but in this case, the terminals V□, V2 or 11. Connection to I2 becomes a problem.

To solve this problem, as shown in FIG.
1. By connecting to I2 and forming a loop in the middle of the lead wire, the number of interlinked magnetic fluxes is algebraically canceled.

FIG. 4 shows an example of waveforms associated with implementation of the present invention.

Φ in FIG. 4 indicates the magnetic flux change, and VP indicates the terminal V1 of the Hall element 1. ■The voltage between the two, E is the voltage induced in the measurement line, V'P is the voltage at the input terminal 9 of the measuring instrument 8 in the conventional case where the present invention is not applied, and Vp□ is the input terminal after the present invention is applied. When the present invention showing the waveform No. 9 is applied, changes in the magnetic flux Φ can be measured faithfully, and measurement accuracy in the high frequency region can be improved.

In other words, noise-like voltage can be removed. From the above, it can be seen that the present invention is very effective.

In the above embodiment, both the root portion 4a of the output voltage lead wire 4 and the root portion 5a of the control current lead wire 5 are overlapped with the lead wire 3 of the Hall element 1, but the output voltage Base part 4a of lead wire 4 for
Even if the wire ring 11 is formed by only overlapping the wires, substantially the same error eliminating effect as in the above embodiment can be achieved.

Since the magnetic field detector of the present invention does not generate voltage in the lead wires due to changes in the magnetic field to be measured, it is possible to accurately measure changes in magnetic flux up to the high frequency range.

[Brief explanation of the drawing]

Figure 1a is a plan view of a conventional magnetic field detector;
A cross-sectional view taken along line A, FIGS. 2a and 2b are a plan view and a front view of an embodiment of the present invention, FIG. 3 is a system diagram of a magnetic field measuring device using the embodiment, and FIG. 4 1 is a curve diagram showing magnetic flux and voltage waveforms of the conventional method and the present invention. 1...Hall element, 3...Lead wire for output, 4...Lead wire for external connection of output voltage,
5... Lead wire for external connection of control current, 11...
...A wire ring formed by a part of the lead wire.

Claims (1)

[Scope of utility model registration request] A magneto-sensitive element that generates an output voltage according to magnetic flux and is equipped with a marking wire for this output voltage, and a connecting wire made of stranded wire and connected to the tip of the marking wire and leading the output voltage to a measuring device. In the magnetic field detector equipped with the above-mentioned magnetic field detector, a part exposed to the magnetic flux of the connecting wire is formed as a wire ring, and a space curved surface surrounded by the magnetic sensing element, the index line, and the connecting line does not have an area component in a direction perpendicular to the magnetic flux. A magnetic field detector characterized by: