JP3376541B2 - Eddy current magnetic field demagnetization system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eddy current magnetic field demagnetization system, and more particularly to an eddy current magnetic field demagnetization system suitable for canceling an eddy current magnetic field generated from a metal body inside a hollow structure such as a ship.

[0002]

2. Description of the Related Art The geomagnetism at a certain point on the earth is uniformly distributed. When a conductor is swayed in the uniformly distributed geomagnetism, an induced current (eddy current) flows in the conductor, causing eddy currents. It is known that a current magnetic field is generated. For this reason, even in the case of a wooden hull, when the hull sways when the hull has a metal body, an eddy current magnetic field is generated with the hull sway. When an eddy current magnetic field is generated from the hull, this eddy current magnetic field may affect the outside. Therefore, an eddy current magnetic field demagnetization system has been proposed as a system for demagnetizing this eddy current magnetic field. This system is generally composed of a magnetic detector, a control circuit, a power amplifier and a degaussing coil. The degaussing coil is placed near the hollow structure (hull) and the current flowing through the degaussing coil is adjusted. The magnetic field generated from the degaussing coil cancels the eddy current magnetic field generated outside the hollow structure. That is, when the hollow structure sways and an eddy current magnetic field is generated outside the hollow structure, the magnetic detector grounded in the vicinity of the hollow structure detects the geomagnetism, and based on the detected value, the hollow structure is detected. The eddy current magnetic field generated outside the hollow structure is always minimized by calculating the fluctuation amount of the above and controlling the current flowing through the degaussing coil by this calculated value. Note that, as related to this type of conventional technology, for example, it is described in JP-A-1-209391, JP-A-2-109795, JP-B-4-39211, and JP-A-8-78234. Some of them are listed.

[0003]

DISCLOSURE OF THE INVENTION In the prior art,
The fluctuation amount is calculated according to the magnetic detection signal detected by the magnetic detector, and the fluctuation amount of the magnetic detection signal is detected according to the calculated value. However, although the magnetic detection signal is a signal of about several V, since the fluctuation is a very small signal, only the fluctuation is extracted from the magnetic detection signal. For example, in order to detect only fluctuations from the absolute value of geomagnetism, the geomagnetism of the sea near Japan is set as a reference signal, this reference signal is used as a fixed bias, and the deviation between the magnetic detection signal and the fixed bias is calculated. It is designed to detect as minutes. However, according to this method, it is necessary to set the value of the geomagnetism in each direction at each place where the geomagnetism is greatly different, and if the value of the geomagnetism is fixed as a fixed bias, the change of the geomagnetism appears as an error as it is. In particular, since the fluctuation component is amplified by the amplifier, the fluctuation component error becomes large. Further, depending on the detection delay of the magnetic detector (the delay of the electrical detection signal with respect to the geomagnetic sway), optimum control may not be possible.

An object of the present invention is to provide an eddy current magnetic field demagnetization system capable of accurately detecting and demagnetizing only the eddy current magnetic field generated from the hollow structure due to the shaking of the hollow structure.

[0005]

In order to achieve the above object, the present invention provides, as a first system, a magnetic detection means for detecting geomagnetism in the vicinity of a hollow structure, and a detection output of the magnetic detection means. An average value calculation means for calculating an average value of changes; a deviation calculation means for calculating a deviation between the reference value and the detection output of the magnetic detection means using the calculated value of the average value calculation means as a reference value; Eddy current magnetic field elimination signal generation means for generating an eddy current magnetic field elimination signal for eliminating an eddy current magnetic field generated from the hollow structure according to the calculated value of the means, and the hollow structure. An eddy current magnetic field degaussing system is provided, which is arranged in the vicinity of a structure and includes degaussing means for canceling the eddy current magnetic field by causing a magnetic field formed by the eddy current magnetic field erasing signal to act on the eddy current magnetic field. It is intended.

As a second system of the present invention, the latitude / longitude for detecting the latitude / longitude indicating the position of the hollow structure is detected.
Longitude detecting means, and shaking detecting means for detecting pitching and rolling angles associated with shaking of the hollow structure, respectively,
Geomagnetic detection means for detecting vertical and horizontal components of the geomagnetism at the position of the hollow structure from the detection output of the latitude / longitude detection means, and this reference value and the fluctuation detection using the detection output of the geomagnetic detection means as a reference value. A fluctuation component extracting means for respectively calculating deviations from the detection values of the means to extract only fluctuation components, and the hollow structure according to the fluctuation of the hollow structure based on the fluctuation components extracted by the fluctuation component extracting means. And an eddy current magnetic field elimination signal generating means for generating an eddy current magnetic field elimination signal for eliminating an eddy current magnetic field elimination signal generated from the eddy current magnetic field, and a magnetic field formed by the eddy current magnetic field elimination signal arranged near the hollow structure. An eddy current magnetic field degaussing system comprising degaussing means for acting on the eddy current magnetic field to cancel the eddy current magnetic field.

In constructing the eddy current magnetic field demagnetization system, the first system and the second system can be combined to form a dual system. In this case, a configuration is provided in which selection means for selecting an eddy current magnetic field elimination signal generated from one of the systems is provided and the eddy current magnetic field elimination signal selected by this selection means is output to the demagnetizing means of each system. You can

Further, in the system having the function of the first system, the calculated value of the deviation calculating means is based on the set value of the adjustment ratio according to the water depth and the draft when the hollow structure is floated on water. Water depth correction means for correction can be provided.

According to the above-mentioned means, the average value of changes in the detected output is calculated from the detected output of the magnetic detecting means, and the average value is used as a reference value, and the deviation between the reference value and the detected output of the magnetic detecting means is calculated. Therefore, even if the geomagnetism changes due to the detection by the magnetism detecting means, it is possible to accurately detect only the magnetic field of the fluctuation due to the fluctuation of the hollow structure regardless of the change of the geomagnetism.

Further, the latitude and longitude indicating the position of the hollow structure are respectively detected, and the pitching and rolling angles due to the shaking of the hollow structure are respectively detected, and the vertical component of the geomagnetism at the latitude and longitude of the hollow structure and the horizontal component are detected. The components are detected, and these values are used as reference values, and the deviation between each reference value and the pitching / rolling angle is calculated to extract only the fluctuation component, so it is possible to detect it regardless of changes in the geomagnetism. Without adjusting the delay, it is possible to accurately detect only the eddy current magnetic field generated from the hollow structure due to the shaking of the hollow structure.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention. In FIG. 1, the eddy current magnetic field demagnetization system is
As a dual system, two systems of eddy current control device 1
0, 2, each eddy current control device 10, 12 is connected to the current output converter 16, 18 via the signal switch 14, the current output converter 16 is connected to the degaussing coil 20, The current output converter 18 is connected to the degaussing coil 22. Each of the degaussing coils 20 and 22 is wound around a hollow structure 24 composed of a nonmagnetic hull or the like. The degaussing coil 20 is provided for degaussing the eddy current magnetic field of the horizontal component of the eddy current magnetic field generated from the hollow structure 24, and the degaussing coil 22 is the hollow structure 24.
It is provided so as to demagnetize the vertical component of the eddy current magnetic field generated from. That is, in this embodiment,
As a change in the geomagnetism due to the shaking of the hollow structure 24, a horizontal component (component in the Y-axis direction) and a component in the vertical direction (Z
(A component in the axial direction) is detected by the eddy current control devices 10 and 12, respectively, and currents according to the detected values are flown to the degaussing coils 20 and 22, respectively, and are generated from the hollow structure 24 with the shaking of the hollow structure 24. It is designed to demagnetize the eddy current magnetic field. In the present embodiment, the Y-axis component and Z
When detecting the geomagnetism of the axial component, the processing relating to the detected geomagnetism has the same configuration as the Y-axis component and the Z-axis component, so only one component will be described.

The eddy current controller 10 includes a magnetic detector 26,
Average value detection circuit 28, deviation detection amplification circuit 30, detection delay compensation circuit 32, detector distance correction circuit 34, differentiation circuit 3
6. The signal amplification circuit 38 is provided. The magnetic detector 26 is arranged in the vicinity of the hollow structure 24 and detects the horizontal direction (Y axis direction) and the vertical direction component (Z axis direction) of the geomagnetic component formed around the hollow structure 24. It is configured as a magnetic detection means for detecting a static magnetic field, and outputs detection signals to the average value detection circuit 28 and the deviation detection amplification circuit 30, respectively. This signal is
As shown in (a), it is output as a voltage signal. The average value detection circuit 28 is configured as an average value calculation unit that takes in a magnetic detection signal and calculates an average value of changes in this signal. Specifically, as shown in FIG. 2A, the average value ef of the change in the magnetic detection signal is calculated from the maximum value and the minimum value of the magnetic detection signal, and this calculated value is output to the deviation detection amplification circuit 30. It is supposed to do. Deviation detection amplifier circuit 3
0 is the signal from the average value detection circuit 28 as a reference value,
That is, it is configured as a deviation calculating means for calculating the deviation between the magnetic detection signal and the reference value using the reference value as the bias voltage. Even if the level of the magnetic detection signal detected by the magnetic detector 26 changes due to geomagnetism, this deviation is
Since the average value of the magnetic detection signal also changes according to the change of the geomagnetism, even if the geomagnetism changes, only the fluctuation of the geomagnetism due to the fluctuation of the hollow structure 24 is shown.
That is, the bias voltage as the reference value is automatically set according to the geomagnetism. And, as shown in FIG. 2B, this deviation is 90 degrees + with respect to the fluctuation of the geomagnetism.
Since the delay of α is included, as shown in FIG. 2C, the detection delay compensating circuit 32 performs a process of correcting the delay. That is, when the deviation signal is input to the differentiating circuit 36, the differentiating operation is performed on the deviation signal at each timing T1 to Tn to perform delay correction accompanied by the detection delay of the magnetic detector 26, and FIG. As shown in FIG. 5, processing is performed to bring the eddy current magnetic field generated from the hollow structure 24 into the same phase. Further, in order to form a magnetic field having a polarity opposite to that of the eddy current magnetic field (magnetic field shown in FIG. 2E) generated from the hollow structure 24, processing for delaying the phase of the input signal by 90 degrees is performed. The output signal of the differentiating circuit 36 is amplified by the signal amplifying circuit 38, and is output to the current output converters 16 and 18 via the signal switch 14 as an eddy current magnetic field elimination signal for eliminating the eddy current magnetic field. That is, the detection delay compensation circuit 32, the differentiation circuit 36, and the signal amplification circuit 38 are configured as an eddy current magnetic field elimination signal generation means. The signal switcher 14 is configured as a selection unit that selects a signal from one of the eddy current control devices 10 and 12, and the eddy current magnetic field elimination signal selected by the signal switcher 14 is used as a voltage signal for the current. It is input to the output converters 16 and 18. This voltage signal is converted into a current signal by the current output converters 16 and 18, and the current signals are supplied to the degaussing coils 20 and 22, respectively. When current flows through the degaussing coils 20 and 22, the degaussing coils 20 and 22 cause
As shown in (f), a magnetic field having a polarity opposite to that of the eddy current magnetic field generated from the hollow structure 24 is formed. This cancels the eddy current magnetic field generated from the hollow structure 24,
As shown in (g), the residual magnetic field can be made almost zero.

In the system using the eddy current control device 10, since the average value of the change in the earth's magnetism detected by the magnetic detector 26 is obtained and this average value is used as the reference value (bias voltage), the earth's magnetism changes. Also, the bias voltage can be automatically set, and the hollow structure 2 can be obtained from the deviation between the magnetic detection signal detected by the magnetic detector 26 and the bias voltage.
It is possible to reliably detect only the variation of the geomagnetism (fluctuation) associated with the fluctuation of No. 4 above. By supplying a current to the degaussing coils 20 and 22 based on this detected value, the eddy current magnetic field generated from the hollow structure 24 can be surely degaussed, which can contribute to the improvement of the degaussing performance.

On the other hand, the eddy current control device 12 comprises a latitude / longitude fluctuation detector 40, a geomagnetic detection circuit 42, a geomagnetic fluctuation detection circuit 44, a differentiation circuit 46, and a signal amplification circuit 48. The latitude / longitude motion detector 40 is, for example,
It is composed of a gyro, and constitutes latitude / longitude detecting means for detecting the latitude / longitude indicating the position of the hollow structure 24 and outputting each detected value to the geomagnetic detection circuit 42, and at the same time, swinging the hollow structure 24. And a pitching / rolling angle associated with each of them is output to the geomagnetic fluctuation detecting circuit 44 as a fluctuation detecting means. The geomagnetic detection circuit 42 is configured as a geomagnetic detection unit that detects a vertical component and a horizontal component of the geomagnetism at the position of the hollow structure 24 from the detection signal of the latitude / longitude motion detector 40,
The detection output is output to the geomagnetic sway detection circuit 44. The geomagnetic sway detection circuit 44 uses the detection output of the terrestrial magnetism detection circuit 42 as a reference value to obtain deviations from the pitching / rolling angle detected by the latitude / longitude sway detector 40 by vector operations, and extracts only the sway component. It is configured as a minute extraction means. For example, when the latitude / longitude motion detector 40 detects a pitching or rolling angle as shown in FIG. 3 (a), the geomagnetic motion detection circuit 44 outputs only the motion component as shown in FIG. 3 (b). Signal is output. Since this signal has a delay of 90 degrees with respect to the shaking of the earth's magnetism, processing for shifting the phase by 90 degrees is performed in the differentiating circuit 46. The output signal of the differentiating circuit 46 is amplified by the signal amplifying circuit 48, and the current output converters 16 and 18 are passed through the signal switcher 14.
Is output to. Then, when the voltage signals are converted into current signals by the current output converters 16 and 18 and currents are applied to the degaussing coils 20 and 22, respectively, the degaussing coils 20 and 22 generate the electric current shown in FIG.
A magnetic field as shown in (d) is formed. As a result, even if an eddy current magnetic field as shown in (c) is generated from the hollow structure 24, this eddy current magnetic field is canceled by the magnetic field generated by the degaussing coils 20 and 22, and as shown in (e). , The residual magnetic field becomes almost zero. In this system, the differentiating circuit 46 and the signal amplifying circuit 48 constitute the eddy current magnetic field elimination signal generating means.

In the system using the eddy current control device 12, the latitude and longitude indicating the position of the hollow structure 24 are detected, and the pitching / rolling angle associated with the sway of the hollow structure 24 is detected and detected. Since the vertical and horizontal components of the geomagnetism at latitude and longitude are detected, these detected values are used as reference values, and the deviation between each reference value and the pitching / rolling angle is vector-calculated so that only the fluctuation component is extracted. It is possible to accurately detect only the fluctuation component regardless of the change of the earth's magnetism, and only the fluctuation component (change component) of the eddy current magnetic field due to the fluctuation of the hollow structure 24 is ensured without performing the correction calculation of the detection delay. Can be detected. Then, by supplying a current to the degaussing coils 20 and 22 based on this detected value, the eddy current magnetic field associated with the shaking of the hollow structure 24 can be surely degaussed, which can contribute to the improvement of the degaussing performance.

Next, the adjustment of the eddy current magnetic field will be described. The adjustment of the eddy current magnetic field is a process of confirming whether or not the eddy current magnetic field generated outside the hollow structure 24 is canceled by the eddy current magnetic field demagnetization system.

Assuming that the hollow structure 24 is a hull 50 as shown in FIG. 4, it is difficult to sway the hull 50 itself when adjusting the eddy current magnetic field. A coil 52 and a magnetic sensor 54 are installed below 50, an electric current is supplied to the coil 52 from a power supply device 56, and a geomagnetic field is changed by a magnetic field generated from the coil 52.
This change in geomagnetism is regarded as a change in geomagnetism due to the shaking of the hull 50. That is, the magnetic field generated from the coil 52 causes a simulated vibration. In this case, the distance between the magnetic sensor 54 and the sensor 50 is the water depth,
Since the magnetic field generated by the coil is not constant due to the change in the draft but may be attenuated due to the relationship between the distance between the magnetic sensor 54 and the coil 52, it is necessary to correct the distance.

Therefore, in the present embodiment, when the eddy current magnetic field is adjusted, the output signal of the detector distance correction circuit 34 as the water depth correction means is input to the differentiation circuit 36 only during the adjustment. This detector distance correction circuit 34
When a value related to water depth is entered, the set value related to the ratio of adjustment according to the set water depth and draft is automatically corrected, and the ratio of adjustment according to water depth and draft is differentiated by the differentiation circuit 36.
Is configured to perform the water depth correction by multiplying the input signal of.

As described above, when adjusting the eddy current magnetic field, the distance correction of the detector can be automatically performed only by inputting the value relating to the water depth, and the calculation of the correction value and the correction processing are unnecessary.

In the above-mentioned embodiment, the biaxial component is explained as the fluctuation of the geomagnetism, but the same configuration can be applied to the case of detecting the triaxial component. Again 1
It is also possible to configure a system that detects only the axial component and demagnetizes it.

[0022]

As described above, according to the present invention,
Geomagnetism near the hollow structure is detected as a magnetic detection signal,
The average value of the change in the detected value is calculated, the difference between the reference value and the magnetic detection signal is calculated using this average value as the reference value, and the change in the eddy current magnetic field due to the shaking of the hollow structure is detected from this deviation. Therefore, it is possible to reliably detect only the change in the eddy current magnetic field due to the sway of the hollow structure regardless of the change in the geomagnetism, and it is possible to contribute to the improvement of the demagnetization performance. Further, according to the present invention, the latitude and longitude indicating the position of the hollow structure are respectively detected, and the pitching and rolling angles associated with the shaking of the hollow structure are detected, and the vertical component of the geomagnetism at the detected latitude and longitude is detected. And the horizontal component are detected, and these detected values are used as reference values, and only the fluctuations are extracted based on the deviation between each reference value and the pitching / rolling angle. Not only can it be accurately detected, but it is possible to reliably detect only the fluctuation of the eddy current magnetic field due to the fluctuation of the hollow structure without performing the correction calculation of the detection delay, which contributes to the improvement of the demagnetization performance. You can

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a system showing an embodiment of the present invention.

FIG. 2 is a waveform diagram for explaining the operation of the eddy current control device.

FIG. 3 is a waveform diagram for explaining the operation of another eddy current control device.

FIG. 4 is a diagram for explaining a method of adjusting an eddy current magnetic field.

[Explanation of symbols]

10, 12 Eddy current control device 14 signal switch 16, 18 Current output converter 20, 22 Degaussing coil 26 Magnetic detector 28 Average value detection circuit 30 Deviation detection amplification circuit 32 Detection delay compensation circuit 34 Detector distance correction circuit 36 Differentiating circuit 38 Signal amplification circuit 40 Latitude / longitude motion detection circuit 42 Geomagnetic detection circuit 44 Geomagnetic fluctuation detection circuit 46 Differentiation circuit 48 signal amplifier circuit

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01F 13/00 B63G 9/06

Claims (4)

(57) [Claims] 1. A magnetic detection means for detecting geomagnetism in the vicinity of a hollow structure, an average value calculation means for calculating an average value of changes in the detected output of the magnetic detection means, and a calculated value for the average value calculation means. Deviation calculation means for calculating the deviation between this reference value and the detection output of the magnetic detection means as a reference value, and generated from the hollow structure with the shaking of the hollow structure based on the calculated value of the deviation calculation means. Eddy current magnetic field erasing signal generating means for erasing the eddy current magnetic field erasing signal, and a magnetic field formed by the eddy current magnetic field erasing signal which is arranged in the vicinity of the hollow structure. An eddy current magnetic field degaussing system comprising a degaussing unit that acts on a current magnetic field to cancel the eddy current magnetic field. 2. Latitude / longitude detecting means for detecting the latitude / longitude indicating the position of the hollow structure, shaking detection means for detecting pitching / rolling angles associated with shaking of the hollow structure, and latitude / longitude detecting means, respectively. Geomagnetic detection means for detecting the vertical and horizontal components of the geomagnetism at the position of the hollow structure from the detection output of the longitude detection means, and the detection output of the geomagnetism detection means as a reference value, and the detection of the reference value and the fluctuation detection means. A fluctuation component extracting means for calculating a deviation from each value and extracting only the fluctuation component, and a fluctuation component extracted by the fluctuation component extracting means that is generated from the hollow structure along with the fluctuation of the hollow structure. An eddy current magnetic field elimination signal generating means for generating an eddy current magnetic field elimination signal for eliminating the eddy current magnetic field, and an eddy current magnetic field elimination signal which is arranged in the vicinity of the hollow structure. Eddy current magnetic field degaussing system, comprising: a demagnetizing means for canceling the eddy current magnetic field by causing the generated magnetic field to act on the eddy current magnetic field. 3. A magnetic detection means for detecting geomagnetism in the vicinity of a hollow structure, an average value calculation means for calculating an average value of changes in the detected output of the magnetic detection means, and a calculated value for the average value calculation means. Deviation calculation means for calculating the deviation between this reference value and the detection output of the magnetic detection means as a reference value, and generated from the hollow structure with the shaking of the hollow structure based on the calculated value of the deviation calculation means. First eddy current magnetic field elimination signal generation means for generating an eddy current magnetic field elimination signal for eliminating the eddy current magnetic field, and latitude / longitude detection means for detecting the latitude / longitude indicating the position of the hollow structure, respectively. A shaking detection means for detecting the pitching / rolling angle associated with the shaking of the hollow structure, and a vertical component of the geomagnetism at the position of the hollow structure and the water level from the detection output of the latitude / longitude detection means. A magnetic field detecting means for detecting the minute, and a motion amount extracting means for extracting only the motion component by calculating the deviation between the reference value and the detection value of the motion detecting means using the detection output of the geomagnetic detection device as a reference value. A second eddy current for generating an eddy current magnetic field elimination signal for eliminating an eddy current magnetic field generated from the hollow structure due to the fluctuation of the hollow structure based on the fluctuation component extracted by the fluctuation component extraction means. Magnetic field erasing signal generating means, selecting means for selecting an eddy current magnetic field erasing signal generated by the first eddy current magnetic field erasing signal generating means or the second eddy current magnetic field erasing signal generating means, and arranged near the hollow structure. Eddy current magnetic field degaussing means for deactivating the eddy current magnetic field by causing the magnetic field formed by the eddy current magnetic field erasing signal selected by the selecting means to act on the eddy current magnetic field. Temu. 4. The water depth correction means for correcting the calculated value of the deviation calculation means based on the set value of the adjustment ratio according to the water depth and the draft when the hollow structure is floated on water. The eddy current magnetic field demagnetization system according to 1 or 3.