JPS6128104B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel means of flux gated magnetic field detection.

As a conventional method for detecting magnetic fields, Hall generators are not suitable for detecting magnetic fields in places where temperature changes are large, such as inside a motor, because their detection sensitivity varies greatly with temperature, or they are not suitable for detecting magnetic fields in places where temperature changes are large, such as inside a motor, or they are not suitable for detecting magnetic fields in places where temperature changes are large, such as inside a motor. Generally speaking, the method of integrating the induced voltage of the search coil in Moreover, prior art fluxgate type magnetic field detectors are suitable for detecting minute magnetic fields, but are inadequate for detecting strong magnetic fields such as those inside a motor.

The present invention focuses on the characteristics of a fluxgate magnetometer, improves its construction, and provides a means that can also detect the magnetic field inside the motor.

FIG. 1 is an explanatory diagram of the principle of the present invention. Hex
2 indicates a detection element 1 consisting of a DC magnetic field to be detected, 2 a spiral magnetic body, 3 an excitation winding, and 4 a detection winding.

That is, this detection element 1 has an excitation winding 3 and a detection winding 4, which are so-called toroidal windings, extending all around the cross section of a magnetic core made by spirally winding a magnetic material 2. This is what I did.

FIG. 2 shows a means for manufacturing a spiral magnetic body 2 according to the present invention.

Usually, a hollow cylindrical body 5 made of a non-magnetic and electrically insulating material is used as the winding frame of the spiral magnetic material. Further, the entire detection element is integrated with a resin or the like having good electrical insulation and heat resistance.

This magnetic field detection element 1 is intended to detect a magnetic field Hex having a component in the same direction as the central axis of the spiral magnetic body 2, as shown in FIG.

In addition, depending on the strength of the magnetic field Hex to be detected,
The purpose is to configure in advance a detector with sensitivity suitable for the purpose of the detector, such as for strong magnetic fields or weak magnetic fields.

Therefore, in the configuration of the helical magnetic body 2, the helical lead angle θ is set small for a strong magnetic field and large for a weak magnetic field. Since contact between each turn of the helical magnetic material is detrimental to the magnetic field detection function, an appropriate gap G is provided between the turns.

The spiral magnetic body 2 is, for example, as shown in FIG.
It is also possible to obtain the magnetic material 2 by first making a long hollow cylindrical body 5 in which the magnetic material 2 is wound spirally over almost the entire length, and then cutting it to a desired length l. .

As the material of the spiral magnetic body 2, for example, the third
A well-known practical wound core material as shown in the figure can be used.

FIG. 4 is an electrical schematic diagram when measuring the magnetic field Hex by the detection element 1, and FIGS. 5 to 10 are diagrams illustrating its operation.

So, here's how it works.

In FIG. 4, the detection element 1 is shown in a simplified manner within the dotted line.

The excitation winding 3 of the detection element 1 has both ends connected to an AC power source 6 for excitation.

Both ends and the center tap of the detection winding 4 are connected to a detection circuit consisting of a pair of rectifiers 7, 8 and resistors 9, 10, respectively, as shown.

Voltage Vd across detection terminals 11 and 12 across a pair of resistors 9 and 10 connected in series in the detection circuit
This results in a signal output corresponding to the detected magnetic field Hex.

Signal output Vd that has positive or negative polarity depending on the directionality of the detected magnetic field Hex and is proportional to the magnetic field Hex.
In order to function in such a way as to obtain Because it has a big impact,
It is necessary to adjust these values or characteristics to obtain the best combination conditions.

Now, suppose that the detection element 1 shown in FIG. 1 is used with the connections shown in FIG. 4.

When the detected magnetic field Hex is zero, the spiral magnetic body 2 operates along a symmetrical rectangular hysteresis loop 50 as shown in FIG. 5, and the detection winding 4 has a waveform as shown in FIG. 60 voltages are induced.

Here, the turns ratio n mentioned earlier, the excitation voltage
The combination of Ve, the characteristics of the rectifiers 7 and 8, etc. is such that both amplitudes of the induced voltage to the detection winding 4 are in the dead zone (-E
~+E).

Therefore, in this case when the magnetic field Hex=0, the signal output obtained through the detection circuit is Vd=0.

By the way, when a constant magnetic field Hex acts in the direction of the central axis of the helical magnetic body 2, the magnetic field H along the length direction of the helical magnetic body 2 is equal to the lead angle θ of the helix.
Then, H=Hex・Sinθ.

Here, the lead angle θ is determined in advance to an appropriate value according to the strength of the detected magnetic field Hex, so
The magnetic body 1 is not magnetically saturated and operates along an asymmetric hysteresis loop 51 under biased magnetization caused by the magnetic field H, as shown in FIG.

Therefore, the induced voltage in the detection winding 4 becomes an asymmetric wave including even-order harmonics, such as a curved waveform 91 in FIG. 9a.

The voltage time integral values for the positive and negative polarity sections of the voltage waveform are equal in phase.

When this voltage is detected, a signal with a magnitude exceeding the threshold level E as shown in Figure 9b is output.
Vd, that is, a curved waveform 92 is obtained.

For the same reason, when the direction of the detected magnetic field Hex is opposite to that in FIG. 4, the signal output Vd is different from the waveform 92 in FIG. The result is an inverted waveform 93.

In this example, when the signal output Vd was connected to a voltmeter (not shown) and the operating characteristics were investigated, a proportional relationship (straight line 100 ) is accepted.

In this way, the present invention can be said to be a magnetic sensor that is compact and robust, can be used at a high temperature, and can further extend the detection range to strong magnetic fields.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of the present invention, FIG. 2 is a conceptual diagram of a means for manufacturing a spiral magnetic body according to the present invention,
Fig. 3 is an explanatory diagram of the characteristics of the magnetic material constituting the present invention, Fig. 4 is an electrical schematic diagram of magnetic field measurement to which the present invention is applied, and Figs. 5 to 10 are explanatory diagrams of its operation. be. 1...Detection element, 2...Spiral magnetic body, 3...
Excitation winding, 4...Detection winding, 5...Hollow cylindrical body,
6...AC power supply, 7,8...diode, 9,1
0...Resistance, 11, 12...Detection terminal.

Claims (1)

[Claims] 1. A magnetic core made by winding a band-shaped magnetic material having square hysteresis ring characteristics around the outer periphery of a non-magnetic hollow cylinder in a spiral manner, with the bands spaced apart from each other; A detection winding wound in a toroidal winding shape that passes through the hole formed and surrounds the cross section in the longitudinal direction of the magnetic core, and a detection winding that passes through the hole formed by the inner circumference of the magnetic core and separate from the detection winding in the longitudinal direction of the magnetic core. A magnetic field detector comprising: an excitation winding wound in a toroidal winding shape surrounding a cross section of the magnetic field detector;