JP2782316B2 - Leakage magnetic flux detection device and switching power supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a magnetic flux leaking from various devices and measures it against EMC (electromagnetic compatibility) and EMI (electromagnetic interference noise), or simply detects the frequency of the leaked magnetic flux. To be installed in magnetic information devices such as magnetic card systems and detection and guidance systems such as automatic guided vehicles, or equipment that is in continuous use to detect the onset of sudden failures and determine the timing of replacement. And a switching power supply using the leakage magnetic flux detection device.

[0002]

2. Description of the Related Art Conventionally, there are various products such as a detection coil array using a so-called one-turn air-core coil, a probe having a number of windings having a ferrite core, and a detection coil using a high impedance coil (see Japanese Patent Application Laid-Open No. 62-237363). It is used for

[0003]

However, the probe array using the one-turn air-core coil as described above has many difficulties in manufacturing, and the cost is increased due to a decrease in yield and the like. Further, when looking at one probe unit, the total amount of magnetic flux interlinking with the cross-sectional area and the detection voltage obtained at that frequency are determined, so that increasing the cross-sectional area and increasing the detection sensitivity lowers the spatial resolution. There was a trade-off relationship.

[0004] The above relationship is the same in a probe having a ferrite core. For example, if the cross-sectional area of the ferrite core is increased in order to increase the amount of interlinkage and increase the detection sensitivity, the spatial resolution is reduced. .

Further, since the coupling between the ferrite core and the winding is strengthened and the impedance is increased, the upper limit of the detection frequency is lowered. Further, when the cross-sectional area of the ferrite member used is increased, there is a problem that the effective magnetic permeability decreases due to an increase in the shape ratio, and the same tendency is caused.

SUMMARY OF THE INVENTION An object of the present invention is to provide a detection circuit system which can be used in a practical use, to improve the resolution and the detection characteristics sufficiently, and to facilitate manufacture and reduce cost. It is an object of the present invention to provide a switching power supply device capable of easily determining a life and a failure by using the device and its leakage magnetic flux detection device.

[0007]

In order to achieve the above object, a leakage magnetic flux detecting apparatus according to the present invention comprises a detecting probe comprising at least a pair of individual coils, and detecting a magnetic flux leakage by an electromagnetic induction method. , Winding is performed so that one individual coil is in the opposite phase to the other individual coil, and each individual coil is connected to a differential amplifier by a lead wire. The present invention is characterized in that an amplified signal is obtained by simultaneously performing an addition operation of a signal component and a subtraction operation of a noise component of each individual coil.

The winding of the individual coil has a resistance of 3.0 × 1
It is characterized by being formed of a material of gold, silver, copper, aluminum, or an alloy thereof having a value of 0 to ⁸ Ωcm or less.

[0009] Further, the invention is characterized in that the pair of individual coils have the same center axis of the winding and the winding direction is substantially perpendicular to the center axis.

[0010] Further, a support for supporting the pair of individual coils is formed of glass or plastic.

The individual coils of the pair of individual coils form a half circle or a half of a square, and the two individual coils form a circle or a square, and the two individual coils are arranged on the same plane. I do.

[0012] Further, the invention is characterized in that the windings of the individual coils are formed of a superconductive member.

[0013] Also, the present invention is characterized in that the windings of the individual coils are three-dimensionally formed on a substrate by plating.

The support for one of the windings of the pair of individual coils is made of a magnetic material, and the support for the other winding is made of a material different from that of the one of the windings. The magnitude of the magnetic permeability of the body is made equal, and the frequency band of the magnetic permeability of each support is set to a predetermined value (f ₁ , f ₂ ) or less,
It is further characterized in that f ₁ <f ₂ .

Further, each support is formed by dispersing different magnetic materials on a flexible plastic substrate, and each support is formed by forming a winding of an individual coil as a printed winding to reduce the frequency of the leakage magnetic flux. f ₁ hereinafter, characterized in that the detectable from f ₁ as f _2, f ₂ or more ternary.

[0016] Further, the present invention is characterized in that an insulating plastic in which magnetic ferrite fine particles are dispersed is used as a support for supporting the winding.

Further, according to the present invention, there is provided a switching power supply device in which a switching circuit including a switching transistor, a switching transformer, a choke inductor, and the like is provided between an input power supply and an output unit. A detecting probe in the leakage magnetic flux detecting device is provided in the vicinity of the switching transformer or the choke inductor, and a control means for determining a life and a failure by increasing or decreasing a leakage magnetic flux detected by the detecting probe is provided.

[0018]

[Function] When detecting the amount of magnetic flux leakage from the object to be measured,
The voltage V generated in the individual coil serving as the detection probe can be generally expressed by (Equation 1).

[0019]

V = dφ / dt = S · dB / dt where S: coil cross-sectional area, B: magnetic flux density, φ: magnetic flux,
t: Time.

Here, in the leakage magnetic flux detection device according to the present invention, the components of the leakage magnetic flux flowing into each of the pair of individual coils are voltages generated according to (Equation 1), and the noise component is the leakage magnetic flux. Phase is different from that of
Since the voltage is subtracted by the individual coils, the voltage generated by the noise component decreases.

Further, by using a material having a low resistance value or a superconducting member as the winding material of the individual coil, the DC resistance is reduced, and detection up to high frequencies is performed with high accuracy.

Further, by forming the support for supporting the individual coils from glass and plastic which are insulating materials having low dielectric loss, eddy current loss and dielectric loss at high frequencies are suppressed.

When the pair of individual coils is viewed as a whole, the individual coils are arranged in a circle or a square, so that the solid angle to the object to be measured can be accurately defined, and the spatial resolution of the measurement can be improved. Is improved.

Further, by forming the windings of the individual coils by a plating method, it is easy to manufacture even a winding having a small diameter.

Further, by forming each support of the windings of the pair of individual coils with materials having different frequency bands of magnetic permeability, the frequency of the leakage magnetic flux can be discriminated in three stages.

Further, by providing the detection probe, which can discriminate the frequency of the leakage magnetic flux in three stages, with flexibility, the degree of freedom of arrangement on the object to be measured is increased, and the detection target of the leakage magnetic flux is expanded.

Further, by using a material in which magnetic ferrite fine particles are scattered in an insulating plastic for the support of the windings of the individual coils, the magnetic permeability becomes constant up to a high frequency, and the detection sensitivity can be increased in a wide band. Will be possible.

Further, in the switching power supply according to the present invention, by detecting the leakage magnetic flux of the switching transformer or the choke inductor by using the leakage magnetic flux detection device according to the present invention, it is possible to determine the life and occurrence of the failure. .

[0029]

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

FIG. 1 is an explanatory view for explaining the principle of the magnetic flux leakage detecting device according to the present invention, in which two support jigs 1 and 2 are used.
A detection probe is constituted by a pair of individual coils 5 and 6 provided with detection windings 3 and 4 so as to have opposite phases to each other. From the detection windings 3 and 4, lead lines 7 and 8 for deriving detection signals (voltages V ₁ and V ₂ ) are connected to a detection circuit described later.

In FIG. 1, φ ₁ and φ ₂ are leakage magnetic flux components from the DUT (not shown), and φ _n1 and φ _n2 are noise components.

FIG. 2 is a diagram showing a basic configuration of the detection circuit. Reference numeral 10 denotes a differential amplifier connected to the lead wires 7 and 8 of the individual coils 5 and 6, and reference numeral 11 denotes an amplifier. Amplifier 10
Assuming that the amplification factor of the amplifier 11 is g ₁ and the amplification factor of the amplifier 11 is g ₂ , A,
The output at point B is as shown in (Equation 2).

[0033]

## EQU2 ## Signal output at point A = (V ₂ −V ₁ ) × g ₁ Signal output due to noise component at point A = (v _n2 −v _n1 ) × g ₁ Signal output at point B = (V ₂ −V ₁ ) × g ₁ × g ₂ Signal output by noise component at point B = (v _n2 −v _n1 ) × g ₁
× g ₂ Here, in FIGS. 1 and 2, the leakage magnetic flux components φ ₁ and φ ₂ are
At the same time it flows into each of the individual coils 5 and 6, the voltage V _1, V ₂ generated according to equation (1). On the other hand, since the noise components φ _n1 and φ _n2 have different phases from the leakage magnetic flux components φ ₁ and φ ₂ , the voltages are subtracted by the individual coils 5 and 6 having opposite phases, and the voltages generated by the noise components φ _n1 and φ _n2 are generated.
(v _n1 , v _n2 ) is significantly reduced. The relationship between these voltages is
It can be expressed by (Equation 3).

[0034]

## EQU3 ## V ₁ = dφ ₁ / dt ₁ V ₂ = dφ ₂ / dt ₂ v _n1 = dφ _n1 / dt ₁ v _n2 = dφ _n2 / dt ₂ Therefore, the S / N ratio is

[0035]

S / N = (V ₂ −V ₁ ) / (v _n1 −v _n2 ) Since V ₁ and V ₂ have the opposite polarities and the same size in (Equation 4), they can be transformed into (Equation 5).

[0036]

S / N = 2V ₁ / (v _n1 −v _n2 ) From this ( _Equation 5), it can be seen that if the noise conditions are further improved, a significant improvement in the S / N ratio can be expected.

FIG. 3 is a structural view of the first embodiment of the present invention. Reference numeral 20 denotes a supporting jig 21 having forked portions 21a and 21b formed at the lower end thereof, and a supporting jig 21 for the forked portions 21a and 21b. It comprises windings for detection 22 and 23, which are wound in opposite phases to form a pair of individual coils 5 and 6, and lead wires 24 and 25 extending from the windings for detection 22 and 23. A detection probe, 26 is a driving device for moving the detection probe 20 three-dimensionally in X, Y, and Z, and 27 is a differential connected to detection windings 22, 23 via leads 24, 25. An amplifier, 28 is a signal processing system, 29 is an A / D (analog / digital) converter, and 30 is a control data operation processing unit.

FIG. 4 is a flowchart of the operation of the first embodiment. The detection probe 20 is moved to a measurement point by the driving device 26 (S1-1), and the leakage magnetic flux from the object at that measurement point is measured. Is obtained as described above, and an output signal from which a noise component is canceled is obtained (S1-2). After the output signal is amplified by the differential amplifier 27 (S1-3), the signal is further processed using the band-pass filter and the spectrum analyzer of the signal processing system 28.
/ N ratio is increased (S1-4). This signal is input to the control data calculation processing section 30 via the A / D converter 29 (S1-5), and data processing for obtaining a data file such as distribution data is performed (S1-6).

Here, it is possible to obtain both the spatial resolution which is important in the present invention and the output required for detection. In this case, the problems are the sensitivity correction and the measurement accuracy of the manufactured detection probe. It is a guarantee.

FIG. 5 is an explanatory view of the detection sensitivity compensation of the detection probe in the present embodiment. In FIG. 5, an excitation coil 33 connected to an oscillator 31 and a high-frequency amplifier 32 to form a high-frequency magnetic field serving as a reference is provided. The same detection probe 20 and driving device 26 as those described with reference to FIG. 3 are arranged, and the detection voltage of the detection probe 20 is amplified by a differential amplifier 34 having an input impedance of 1 MΩ. The detection is performed using the analyzer 35, and the sensitivity and the band of the detection probe 20 are determined from the basic components.

As described above, by using the detection probe capable of detecting the correction and the band, it is possible to grasp the amount of leakage magnetic flux generated by the entire device before the product is shipped.

FIGS. 6A to 6E are block diagrams showing a manufacturing process for explaining an example of a manufacturing method for making the detection probe easier, and FIGS. 7A to 7E are FIGS. FIG. 7 is an explanatory view of a change in the configuration in the manufacturing process corresponding to the steps of FIGS. 6A to 6E, and a supporting jig 40 made of insulating plastic having two forked portions 40 a and 40 b formed at one end. A winding groove 41 and a wiring pad groove 42 are formed thereon (FIGS. 6 (a) and 7 (a)), and the whole is immersed in an electroless plating solution to form a base layer (electroless plating layer). 43
Is formed on the surface (FIGS. 6 (b) and 7 (b)). Thereafter, the underlying layer 43 other than the winding groove 41 and the wiring pad groove 42 is removed by polishing (FIGS. 6C and 7C).

A winding portion 44 and a wiring pad 45 are selectively formed by electrolytic plating on the underlying layer 43 in the winding groove 41 and the wiring pad groove 42 (FIGS. 6D and 7D). )),afterwards,
Wiring is performed so that the winding portions 44 of the forked portions 40a and 40b have phases opposite to each other (FIGS. 6 (e) and 7 (e)). In this example, the forked part 40
The wiring pads 45 on the rear surface of
And a lead wire 47 is connected to each of the two wiring pads 45 on the surface.

As described above, the detection probe can be more easily manufactured by forming the winding portion by plating instead of winding the coil.

FIGS. 8 (a) to 8 (e) are block diagrams showing steps for explaining an example of manufacturing a detection probe using a superconducting material as the material of the winding, and FIGS. FIG. 9 is an explanatory diagram of a change in a configuration in a manufacturing process corresponding to the steps of FIGS.
A winding groove 51 and a wiring pad groove 52 are formed on a supporting jig 50 made of insulating aluminum having two forked portions 50a and 50b formed at one end (FIGS. 8A and 9). (a)).

By mixing powders of Y ₂ O ₃ , BO and Cu ₂ O, Y
A powder mixture of ₁ B ₂ Cu ₃ O ₇ composition was prepared (FIG. 8).
(b), FIG. 9 (b)), the powder mixture is put into the winding groove 51 and the wiring pad groove 52 (FIG. 8 (c), FIG. 9 (c)), and the groove is formed by sintering. in 51 and 52 _{Y 1} B ₂ Cu ₃ O 6.7~7 winding portion 54 of the superconducting material of the composition to form a wiring pad 55 (FIG. 8 (d), the FIG. 9 (d)).

Thereafter, wiring is performed so that the winding portions 54 of the forked portions 50a and 50b have opposite phases to each other (FIGS. 8 (e) and 9 (e)).
In this example, wiring pads on the back surface of the forked portions 50a and 50b
55 are connected to each other by a normal conductive member 56, and a lead wire 57 is connected to each of two wiring pads 55 on the surface.

As described above, by using a superconducting material for the winding material, the DC resistance value is reduced, and thermal noise generated from the winding can be reduced by keeping the temperature lower than room temperature.

Since the normal conducting member 56 is connected to the end of the winding portion 54, no steady current flows through the winding portion 54, and there is no problem in detecting the leakage magnetic flux. Lead wire to amplifier 57
It is also conceivable to use a superconducting material in order to reduce the resistance.

FIG. 10 shows that a high-temperature superconducting material (Y ₁ B ₂
FIG. 6 is a characteristic diagram relating to sensitivity / frequency when Cu ₃ O _x (x = 6.7 to 7) is used, where a is a case where only a normal conductive member is used, b is a case where a winding portion is made of a superconductive material, c shows the case where the winding portion and the lead wire are made of a superconductive material, and it can be seen that the characteristics are improved by using the superconductive member.

FIGS. 11 (a) to 11 (d) are block diagrams showing steps for explaining an example of a method of manufacturing a supporting jig (mold for magnetic core).
FIGS. 12 (a) to 12 (d) are illustrations of members in the process corresponding to FIGS. 11 (a) to 11 (d), for forming a support jig having a bifurcated end. Then, an inverted E-shaped upper mold 61 having a material injection hole 60 and a concave lower mold 62 are formed (FIGS. 11A and 12).
(a)).

In order to prepare a material to be injected into the mold, the magnetic fine particles 63 and the dispersant 64 to be mixed are weighed, and the two are stirred in a container to form the dispersant 64 in which the magnetic fine particles 63 are dispersed. An injection material 65 is made (FIGS. 11 (b) and 12 (b)).
The injection material 65 is injected through the material injection hole 60 between the assembled upper die 61 and lower die 62 (FIGS. 11C and 12C), and the supporting jig is formed. The support jig 66 after the molding is completed is taken out from the upper mold 61 and the lower mold 62 (FIGS. 11D and 12D), and the coils are wound around the fork portions 66a and 66b in opposite phases. Will be.

The use of a magnetic core obtained by dispersing magnetic fine particles with a dispersant is effective in terms of high-frequency sensitivity. FIG. 13 is a characteristic diagram of high-frequency sensitivity.
-B shows a case in which Ni-Zn ferrite cores are used for the magnetic core, and b shows a case in which Ni-Zn ferrite fine particles are dispersed in the magnetic core as shown in Figs. It can be seen that the higher frequency sensitivity is improved.

It is also conceivable to use an insulating plastic in which magnetic ferrite fine particles are dispersed as a supporting jig. 11 (a)-(d) and 12 (a)-
A method similar to the method described in (d) can be used. By using this supporting jig, sufficient high-frequency characteristics can be obtained in a target measurement area.

FIG. 14 shows the frequency dependence of the magnetic permeability of the silicon steel core a, the Mn-Zn ferrite core b, the Ni-Zn ferrite core c, and the dust core d. As described above, in the case where the magnetic ferrite fine particles are dispersed in the insulating plastic, the magnetic permeability is constant up to a range exceeding 100 MHz, and the detection sensitivity can be increased in a wide band (see FIG. 13).

FIG. 15 is a structural view of a main part of a second embodiment of the present invention. In the second embodiment, a plurality of detection windings are provided in parallel on a columnar support jig 21. In FIG. 15, a pair of detection windings 70 and 71 are wound in parallel with opposite phases to each other, and the two detection windings 70 and 71 have the same central axis L and the winding direction is the central axis. L, and one end of each of the detection windings 70, 71 is connected to the connection line 72, and the other end is connected to the differential amplifier through the lead lines 73, 74 as described above. Have been.

FIG. 16 is a block diagram showing a modification of the second embodiment. In this embodiment, two pairs of detection windings 75, 76, 77 are provided on the supporting jig 21 in opposite phases. , 78 are provided in parallel, and the detection windings 75 to 78 have the same central axis L and the winding direction is substantially perpendicular to the central axis L. As shown in FIG. 15, one end of each pair is connected by connection lines 79, 80, and the other end is connected to differential amplifiers 81, 82 via lead lines 83, 84, 85, 86. Output signals from the two differential amplifiers 81 and 82 are added by a sum circuit 87,
The signal is amplified and signal-processed by the processing circuit 88.

FIG. 17 shows a detection probe having the structure shown in FIG. 15 manufactured by using the plating method described with reference to FIGS. 6 and 7. Each of the detection probes is placed on a supporting jig 90 made of insulating plastic. A pair of detection winding portions 93 and 94 composed of a winding portion 91 and a wiring pad 92 are formed by the plating method described above, and the wiring pad 92 is set so that the detection winding portions 93 and 94 have phases opposite to each other. To the differential amplifier, and to the output lines 96 and 97 to the differential amplifier.
Connected by

By forming the winding by the plating method as described above, the wire diameter of the winding can be reduced. Since a general copper winding requires a diameter of 10 μm, the plating method can produce a smaller detection probe.
In addition, since the same winding process can be unified, a detection probe provided with a plurality of detection windings in parallel can be manufactured at low cost.

FIG. 18 is a graph showing the relationship between the number of detection windings and the S / N ratio. It can be seen that the larger the number of detection windings, the higher the S / N ratio.

By the way, as shown in FIG.
(A pair of detection windings are wound in parallel with opposite phases.
When the frequency bands of the magnetic permeability of the magnetic material constituting 21) are f ₁ and f ₂ , each winding has
Generated voltages are Vs ₁ and Vs _2, and each winding has a frequency
Noise voltages generated in the band are denoted by vn ₁ and vn ₂ .
Lever, as with the equation (4), the _{f 1} or less,

[0062]

S / N = 2 Vs ₁ / (vn ₁ −vn ₂ ) Further, from f ₁ to f ₂ ,

[0063]

S / N = ( Vs ₁ + Vs ₂ ) / (vn ₁ −vn ₂ ) Further, when f ₂ or more,

[0064]

S / N = 2 Vs ₂ / (vn ₁ −vn ₂ ) Therefore, as the measuring circuit shown in FIG. 20, parallel between the 100, 101 and the differential amplifier 102 (with different magnetic core) a pair of individual coils provided so as to each other thus in opposite And each individual coil 100, 1
Reference resistances 103 and 10 smaller than the impedance of 01
When the leakage magnetic flux is detected as described above using the detection circuit provided with 4, the relationship between the frequency of the leakage magnetic flux and the detected voltage is as shown in FIG. In FIG. 21, the detection voltage based on the frequency of the leakage magnetic flux has three values, and the frequency of the leakage magnetic flux can be discriminated by a simple configuration.

FIGS. 22 (a) to 22 (c) are block diagrams showing steps for explaining another example of a method of manufacturing a detection probe.
FIGS. 22A to 22C are explanatory diagrams showing changes in the configuration of the manufacturing process corresponding to the steps of FIGS. 22A to 22C. Two types having the same magnitude of magnetic permeability but different frequency bands. Are dispersed in different portions 110a and 110b, respectively, to produce a flexible plastic substrate 110 (FIGS. 22 (a) and 23 (a)). , B are formed by the printed wiring method together with the lead wires 112a, 112b together with the lead wires 112a, 112b so that the phases are opposite to each other (FIGS. 22 (b), 23 (b)). . Thereafter, connection of the differential amplifier 113, peripheral processing, formation of a protective layer, and the like are performed on the plastic substrate 110 (FIGS. 22C and 23C), and the detection probe 114 using the flexible substrate as a support is provided. To complete.

By using the detection probe 114,
Assuming that the frequency bands of the magnetic permeability of the magnetic bodies A and B are f ₁ and f ₂ , the frequency of the leakage magnetic flux is f ₁ or less and f ₁
Thus, discrimination of f ₂ , f ₂ or more can be detected.

The detection probe 114 can be applied to a magnetic card reader. FIG. 24 is a perspective view showing an example of the magnetic card 120, in which 121 is a card support portion, 122 is a card magnetic portion, and the card magnetic portion 122 has the above f ₁ and f _1.
To f ₂ , magnetic signals corresponding to f ₂ or more are written as position information.

FIG. 25 is an explanatory diagram of a magnetic card reader.
The windings 111a and 111b of the detection probe 114 composed of the flexible substrate described with reference to FIGS. 22 and 23 are elastically slidably contacted with the card magnetic section 122, and are fixed at a constant speed.
Is moved, and as described above, the magnetic signal is detected and sent to the signal processing system via the differential amplifier 113, whereby the information can be read.

FIG. 26 is an explanatory view of an unmanned transfer machine using the detection probe made of the flexible substrate. The unmanned transfer machine 130 includes the detection probe 1 described in FIGS. 22 and 23.
14, a signal processing unit 131 consists of the control unit 132., on the running road surface of the unmanned conveying device 130, the f ₁ below, as a magnetic signal position index corresponding from f ₁ to f _2, f ₂ or more Embedded.

In FIG. 26, a detection probe is provided on the traveling road surface.
By detecting the magnetic signal by resiliently contacting the windings 111a and 111b of the 114, the differential amplifier 113 and the signal processing unit 1 are detected.
Signal processing is performed at 31, and traveling control of the automatic guided machine 130 is performed at the control unit 132.

Incidentally, the DC resistance of the detection winding in the detection probe of the present embodiment is problematic in the following points.

If the DC resistance is large, matching is required even if the input impedance of the amplifier used for the measuring instrument is sufficiently large.

If the DC resistance is large in relation to the inductance of the winding itself and the line capacitance, the resonance frequency decreases,
Detection up to high frequencies becomes impossible. FIG. 27 shows the relationship between the resonance frequency of the probe for detecting the magnetic core of the Ni-Zn ferrite core and the DC resistance.

To reduce the DC resistance, the skin effect cannot be ignored in the case of a thick winding, and the accuracy of measurement becomes a problem.

A non-magnetic winding is desirable because the path of the leakage magnetic flux changes.

In order to correspond to the above, the materials of the windings include gold, silver, and the like having low wire resistivity (3.0 × 10 to ⁸ Ωm or less).
Copper, aluminum, and their alloys are preferred.

Further, as the supporting jig around which the detection winding is wound, it is desirable to use an insulating material having a low dielectric loss (tan δ) in order to suppress eddy current loss and dielectric loss at high frequencies. Glass and plastic are particularly preferred for high-frequency detection. FIG. 28 shows a characteristic diagram relating to sensitivity / frequency of a supporting jig made of an insulating material having a low dielectric constant.

FIGS. 29 and 30 are explanatory views of the shape of the detection probe. FIG. 29 (a) is a front view using a cylindrical support jig, and FIG. 29 (b) is the same. 29 is a side view of FIG.
5A and 5B, a slit 141 is provided at the center of the cylindrical support jig 140 in the axial direction, and semicircular portions 142a and 142b having the same shape are formed at the end portions. The detection windings 143 and 144 are applied to 142b in opposite phases to each other, and a pair of detection windings 14
At 3,144, one circular coil is formed. The number of windings of the detection windings 143 and 144 is determined by a required frequency band and an output amount.

FIG. 30A is a front view of a prismatic support jig.
FIG. 30 (b) is a side view of the supporting jig, and FIGS.
In (b), a prismatic support jig 1 forming a square in front view
A slit 151 is provided at the center in the axial direction at 50, rectangular portions 152a and 152b of the same shape are formed at the tip portion, and detection windings 153 and 154 are applied to both rectangular portions 152a and 152b in opposite phases to each other. The detection windings 153 and 154 form one square coil.

If the support jig 140 on the cylinder and the prism-shaped support jig 150 are used, the solid angle up to the object to be measured can be accurately defined, so that the spatial resolution of measurement can be improved. Will be possible.

FIGS. 31 and 32 are circuit diagrams showing an embodiment of a switching power supply device using the leakage magnetic flux detection device according to the present invention, wherein 160 is an input power supply, 161 is a transformer 162, a diode 163, and a choke inductor. 164, capacitor 165
166 is one of the transformers 162
The switching FET connected to the next side, 167 is a control IC which is a control means for turning on / off the switching FET 166, 168 is a detection probe composed of detection windings 169, 170 having opposite phases as described above, 171 is the detection winding 1
A differential amplifier to which the detection signals of 69 and 170 are input, a peak detector 172 connected to the output side of the differential amplifier 171, and 173 and 17
Reference numeral 4 denotes a signal comparison amplifier. These signal comparison amplifiers 173 and 174 are provided with the peak detector 172 and the control IC 167.
, And between the output side of the DC-DC converter 161 and the comparison port Pc of the control IC 167.

The detection probe 168 is installed close to the transformer 162 in the embodiment of FIG. 31, and is installed close to the choke inductor 164 in the embodiment of FIG. The magnetic flux signal is detected by the detection probe 168, and the increase or decrease of the leakage magnetic flux signal is obtained by the peak detector 172 and the signal comparison amplifiers 173 and 174, and is input to the control IC 167. The control IC 167 determines the life and the occurrence of a failure based on the increase and decrease of the leakage magnetic flux.

An appropriate leakage flux signal can be obtained by adjusting the frequency band of the magnetic permeability of the supporting jig provided with the detecting winding of the detecting probe 168 used in the switching power supply device to the switching frequency. FIG. 33 is a characteristic diagram of the detection sensitivity depending on the material of the supporting jig, a is a silicon copper core (supporting jig), b is an Mn-Zn ferrite core, c is a Ni-Zn ferrite core, and d is Dust core, e
Is a characteristic curve without a core.

From FIG. 33, when the purpose is to detect a frequency of about 10 kHz, a core made of silicon steel is effective, and at 1 MHz or less, a Mn-Zn ferrite core is effective. It can be seen that at higher frequencies, a Ni-Zn ferrite core or dust core is effective.

[0085]

As described above, according to the first and third aspects of the present invention, the leakage magnetic flux detection device of the present invention can reduce the noise component in the detection signal of the leakage magnetic flux and improve the detection accuracy.

According to the second and sixth aspects of the present invention, the DC resistance of the winding can be reduced, and detection up to high frequencies can be performed with high accuracy.

According to the fourth aspect of the invention, since the support of the individual coil is formed of an insulating material having a low dielectric loss, eddy current loss and dielectric loss at high frequencies can be suppressed, and the detection accuracy is improved.

According to the fifth aspect of the present invention, the solid angle up to the object to be measured can be accurately defined, and the spatial resolution of the measurement increases.

According to the seventh aspect of the present invention, by forming the windings of the individual coils by the plating method, even a winding having a small diameter can be easily manufactured, and the cost can be reduced.

According to the eighth aspect of the present invention, since the support members of the windings of the pair of individual coils have the same magnitude of the magnetic permeability and different frequency bands of the magnetic permeability, the leakage can be prevented. The frequency of the magnetic flux can be discriminated in three stages.

According to the ninth aspect of the present invention, the detection probe provided with the individual coil according to the eighth aspect has flexibility, and the degree of freedom of arrangement on the object to be measured can be increased. The detection target of the leakage magnetic flux can be expanded.

According to the tenth aspect of the present invention, the detection sensitivity can be increased in a relatively wide band by using an insulating plastic in which fine magnetic ferrite particles are dispersed as the support for the windings of the individual coils. .

The switching power supply of the present invention has the following features.
As described in 11, the life of the switching transformer or the choke inductor and the occurrence of the failure can be determined by detecting the leakage magnetic flux.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for explaining the principle of a leakage magnetic flux detection device according to the present invention.

FIG. 2 is a basic configuration diagram of a detection circuit.

FIG. 3 is a configuration diagram of a first embodiment of a leakage magnetic flux detection device of the present invention.

FIG. 4 is a flowchart of the operation of the first embodiment.

FIG. 5 is an explanatory diagram of detection sensitivity compensation of a detection probe.

FIG. 6 is a block diagram showing a manufacturing process for describing an example of a method for manufacturing a detection probe.

FIG. 7 is an explanatory diagram of a change in the configuration in the manufacturing process of FIG. 6;

FIG. 8 is a block diagram showing steps for explaining an example of manufacturing a detection probe using a superconducting material as a winding material.

9 is an explanatory diagram of a change in the configuration in the manufacturing process of FIG. 8;

FIG. 10 is a characteristic diagram relating to sensitivity / frequency when a high-temperature superconducting material is used as a material of a winding.

FIG. 11 is a block diagram showing a step for explaining an example of a method for manufacturing a supporting jig.

FIG. 12 is an explanatory diagram of a member in a process of FIG. 11;

FIG. 13 is a characteristic diagram of high-frequency sensitivity.

FIG. 14 is a diagram for explaining the frequency dependence of magnetic permeability.

FIG. 15 is a configuration diagram of a main part of a leakage magnetic flux detection device according to a second embodiment of the present invention.

FIG. 16 is a configuration diagram showing a modification of the second embodiment.

17 is an explanatory diagram of a configuration of the detection probe of FIG. 15 manufactured by a plating method.

FIG. 18 is a diagram showing the relationship between the number of windings for detection and the S / N ratio.

FIG. 19 is a diagram for explaining frequency dependence of magnetic permeability.

FIG. 20 is a configuration diagram of a measurement circuit.

FIG. 21 is a diagram for explaining frequency dependency of a detection voltage.

FIG. 22 is a block diagram showing a step for explaining another example of a method for manufacturing a detection probe.

FIG. 23 is an explanatory diagram of a change in the configuration in the manufacturing process of FIG. 22;

FIG. 24 is a perspective view showing an example of a magnetic card.

FIG. 25 is an explanatory diagram of a magnetic card reader.

FIG. 26 is an explanatory diagram of an unmanned carrier using a detection probe.

FIG. 27 is a diagram illustrating a relationship between a resonance frequency of a detection probe and a DC resistance.

FIG. 28 is a characteristic diagram relating to sensitivity / frequency of a supporting jig made of an insulating material having a low dielectric constant.

FIG. 29 is an explanatory diagram of a shape of a detection probe.

FIG. 30 is an explanatory diagram of a shape of a detection probe.

FIG. 31 is a circuit diagram of a first embodiment of the switching power supply device according to the present invention.

FIG. 32 is a circuit diagram of a second embodiment of the switching power supply according to the present invention.

FIG. 33 is a characteristic diagram of detection sensitivity depending on a difference in material of a supporting jig.

[Explanation of symbols]

1,2 ... Supporting jig, 3,4 ... Detection winding, 5,6
... individual coil, 7,8 ... lead wire, 10,171 ... differential amplifier, 20,168 ... detection probe, 160 ... input power supply,
161: DC-DC converter, 162: Transformer, 16
4… Choke inductor, 166… Switching FET,
167: Control IC, 172: Peak detector.

Continuation of front page (56) References JP-A-5-232087 (JP, A) JP-A-4-86552 (JP, A) JP-A-5-296979 (JP, A) JP-A-56-107169 (JP) , A) Japanese Patent Publication No. 58-56830 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01N 27/72-27/90

Claims (11)

(57) [Claims] In a leakage magnetic flux detecting device for detecting a leakage magnetic flux by an electromagnetic induction method, a detection probe includes at least a pair of individual coils, and one of the individual coils has a winding opposite to that of the other individual coil. , And the individual coils are connected to the differential amplifier by respective lead wires, and the differential amplifier simultaneously performs the addition operation of the leakage magnetic flux signal component of each individual coil and the subtraction operation of the noise component of each individual coil. A leakage magnetic flux detection device configured to obtain an amplified signal. 2. The winding of an individual coil having a resistance value of 3.0 × 10 to
^2. The leakage magnetic flux detecting device according to claim 1, wherein the leakage magnetic flux detecting device is formed of a material made of gold, silver, copper, aluminum, or an alloy thereof having a resistivity of ⁸ Ωcm or less. 3. The leakage magnetic flux detection device according to claim 1, wherein the pair of individual coils have the same center axis of the winding and the winding direction is substantially perpendicular to the center axis. 4. A support for supporting a pair of individual coils,
2. The leakage magnetic flux detecting device according to claim 1, wherein the device is formed of glass or plastic. 5. An individual coil of a pair of individual coils forms a half circle or a half of a square, and both individual coils form a circle or a square, and both individual coils are arranged on the same plane. The leakage magnetic flux detection device according to claim 1, wherein 6. The leakage magnetic flux detection device according to claim 1, wherein the windings of the individual coils are formed of a superconducting member. 7. The leakage magnetic flux detection device according to claim 1, wherein the windings of the individual coils are three-dimensionally formed on the substrate by plating. 8. A support for one winding of a pair of individual coils is formed of a magnetic material, and a support for the other winding is formed of a material different from that of the one winding. The magnitude of the magnetic permeability of the supports is made equal, the frequency band of the magnetic permeability of each support is set to a predetermined value (f ₁ , f ₂ ) or less, and f ₁ <f _2. Item 7. A leakage magnetic flux detection device according to Item 1. 9. Each of the supports is formed by dispersing different magnetic materials on a flexible plastic substrate, and the windings of the individual coils are formed as printed windings on each of the supports, and the frequency of the leakage magnetic flux is formed. the f ₁ below, claims, characterized in that the detectable from f ₁ as f _2, f ₂ or more ternary 8
7. The leakage magnetic flux detection device according to claim 1. 10. The magnetic flux leakage detecting device according to claim 1, wherein a magnetic ferrite fine particle dispersed in insulating plastic is used as a support for supporting the winding. 11. A switching power supply device provided with a switching circuit including a switching transistor, a switching transformer, a choke inductor, and the like between an input power supply and an output unit, according to any one of claims 1 to 10. A switching power supply having a detection probe of the leakage magnetic flux detection device in the vicinity of the switching transformer or the choke inductor, and having control means for determining a life and a failure by increasing or decreasing a leakage magnetic flux detected by the detection probe. apparatus.