WO2018126724A1

WO2018126724A1 - Dual-coil coupled multi-wave exploration system

Info

Publication number: WO2018126724A1
Application number: PCT/CN2017/100842
Authority: WO
Inventors: 付志红; 姜升; 朱学贵; 魏秋生
Original assignee: 重庆璀陆探测技术有限公司; 重庆大学
Priority date: 2017-01-09
Filing date: 2017-09-07
Publication date: 2018-07-12
Also published as: CN107065020A; CN107065020B

Abstract

A dual-coil coupled multi-wave exploration system, comprising a transmission control system. A first set of pulse signal output ends of the transmission control system is connected with a master transmitting coil, and a second set of pulse signal output ends of the transmission control system is connected with a slave transmitting coil. The master transmitting coil and the slave transmitting coil are coupled coils and are overlapped in position. A receiving coil module is provided at the edge of the master transmitting coil, and is partially intersected with the master transmitting coil; and the partial orthographic projection of the master transmitting coil is coincide with the partial orthographic projection of the receiving coil module. The dual-coil coupled multi-wave exploration system can realize alternate detection of the deep part and the shallow part, is short in the current turn-off time for the shallow detection, low in loss, high in detection precision and work efficiency, simple in structure and high in mobility; the master transmitting coil and the receiving coil module are intersected partially and thus the mutual inductance influences between the master transmitting coil and the receiving coil are cancelled, so that the exploration precision is improved.

Description

Double coil coupled multi-wave survey system

Technical field

The invention relates to the field of transient electromagnetic detection technology, in particular to a double coil coupling type multi-wave exploration system.

Background technique

Transient electromagnetic method, also known as Time domain electromagnetic method (TEM), is a non-grounded return line or ground line source that emits a pulsed magnetic field underground. During a pulsed magnetic field interval, a coil or ground electrode is used. A method of observing a secondary eddy current field. Simply put, the basic principle of transient electromagnetic method is the law of electromagnetic induction. The decay process is generally divided into early, middle and late stages. The early electromagnetic field is equivalent to the high frequency component in the frequency domain, and the attenuation is fast, and the skin depth is small. The late component is equivalent to the low frequency component in the frequency domain, and the attenuation is slow and the skin depth is large. By measuring the variation of the secondary field with time in each time period after power failure, the geoelectric characteristics of different depths can be obtained.

The application of time domain transient electromagnetic method has been developed from traditional metal minerals and oil and gas resources exploration to environmental engineering, groundwater and geothermal resources, marine topographic surveys, polar research and other applications. The technology of large loop transmitting coils has been relatively mature, but tunnels, mines, etc. are often complicated due to the topographical environment and ten narrow, coil laying is difficult, construction is difficult, and efficiency is low. Under the equivalent emission magnetic moment, the small loop coil technology has the characteristics of small size, light weight, easy to carry, and low environmental requirements. At the same time, it also has simple coil laying, fast acquisition speed, strong anti-interference ability, and horizontal resolution. Higher advantages, small wireframe device is more suitable for aviation electromagnetic exploration, tunnel coal mine advance forecast, and geological exploration in construction limited areas. However, the small wireframe device has a larger coil self-inductance, causing a serious turn-off delay problem. The turn-off delay causes shallow signal loss, which affects the shallow detection effect. Therefore, how to balance the large magnetic moment emission of shallow detection is a small wireframe device problem.

At present, the main problems of domestic transient electromagnetic transmitters are: first, the magnetic field turn-off delay is too long, and the shallow detection information is seriously lost; second, the emission magnetic field is unstable, with the increase of the working time of the power supply system, the power supply system The power will decrease, resulting in a change in the transmitted waveform, poor received signal quality, and large detection error. Third, the detection depth is single, and both shallow detection information and deep detection information cannot be considered at the same time.

Summary of the invention

In view of the above problems, the present invention provides a detecting device capable of detecting shallow and deep layers, the current off time is adjustable, the excitation field is stable and reliable, and the precision is high.

To achieve the above objectives, the specific technical solutions adopted by the present invention are as follows:

A dual-coupling coupled multi-wave survey system, the key of which is: including a launch control system, a first set of pulse signal output ends of the launch control system is connected with a main transmit coil, and a second set of pulse signal output ends of the launch control system Connected from the transmitting coil, the main transmitting coil and the transmitting coil are coupled coils, the main transmitting coil and the transmitting coil overlap, and the magnetic fields generated by the two are enhanced; the emission control system is used to generate continuous or intermittent bipolar 斩The wave pulse signal, the primary transmit coil emits a first excitation field during a first transmit half cycle, and the second excitation field is transmitted from the transmit coil during a second transmit half cycle.

With the above scheme, the emission control system outputs different pulse signals to the main transmitting coil and the transmitting coil at different time periods to realize deep and shallow switching detection.

When performing deep detection, the first pulse signal output end of the emission control system outputs a large-value bipolar chopping pulse signal, the main transmitting coil emits a first excitation field, and the second excitation field is emitted from the transmitting coil, due to the main transmitting coil and From the overlapping of the transmitting coils, the two magnetic fields are enhanced to jointly realize deep detection.

When the shallow detection is performed, the second pulse signal output end of the emission control system outputs a small amplitude bipolar pulse signal, and the second excitation field is emitted from the transmitting coil to realize shallow detection.

Further described, the first excitation field is compensated for the excitation field from the transmit coil during the first transmit half cycle.

During the deep detection process, due to the unstable energy of the transmitting power source or the drop of the power supply voltage, the first excitation field generated in the main transmitting coil may fluctuate, resulting in a decrease in the current in the flat top region of the large magnetic moment current generated by the receiving coil or Wave move. In order to stabilize the constant magnetic field of the large magnetic moment, the second set of pulse signals of the emission control system outputs a compensation current that changes with the current output of the first set of pulse signals.

Further, in order to better realize the switching detection of the deep and shallow layers and at the same time better realize the compensation effect of the second excitation field on the first excitation field, the intensity of the first excitation field is greater than the intensity of the second excitation field. That is, the second excitation field is emitted from the transmitting coil, and a small magnetic field is generated to compensate for the flat top region of the large magnetic moment magnetic field, and the total magnetic field of the large magnetic moment magnetic field flat state is maintained constant, and the compensation small current follows the first group of pulses. The large current of the signal output changes.

Further, the emission control system includes a synchronization controller, a first transmitting circuit, and a second transmitting circuit, and the power terminal of the synchronous controller is connected to the transmitting power source;

a first transmitting circuit is connected to the first group of control outputs of the synchronous controller, and a main transmitting coil is connected to the first group of pulse signal output ends of the first transmitting circuit;

A second transmitting circuit is connected to the second group of control outputs of the synchronous controller, and a slave transmitting coil is connected to the second group of pulse signal output ends of the second transmitting circuit.

The beneficial effects of the above schemes are adopted: in the detection process, the joint action and the independent operation solve the problem that the deep and shallow parts are difficult to balance. Synchronous control is realized by the synchronous controller to avoid the time difference and delay of the deep detection control, and the control reliability and the detection accuracy are improved. The first transmitting circuit and the second transmitting circuit operate independently, and the independence is strong, so that the signal transmission is more reliable.

Further, the first transmitting circuit and the second transmitting circuit are identical in structure, and both are H-bridge circuits;

The four control ends of the first transmitting circuit are respectively connected to the first group of control outputs of the synchronous controller, and the power input end of the first transmitting circuit is connected to the first group of power output terminals of the transmitting power source;

The four control ends of the second transmitting circuit are respectively connected to the second group control output end of the synchronous controller, and the power input end of the second transmitting circuit is connected to the second group power output end of the transmitting power source.

With the above scheme, the first transmitting circuit generates a large current up to several hundred amperes; the second transmitting circuit generates a small current, several amperes to several tens of amperes, and the current off time is short. At the same time, the steepness of the current turn-off is steeper than that of the high-current turn-off, which is beneficial to the acquisition of shallow information, and the shallow detection effect is good.

Further, the bipolar chopping pulse signal outputted by the first pulse signal output end of the emission control system is a bipolar trapezoidal wave, or a bipolar half sine wave, or a bipolar trapezoidal wave, or a bipolar The triangular wave; the bipolar chopping pulse signal outputted by the second pulse signal output end of the emission control system is a bipolar trapezoidal wave, or a bipolar triangular wave, or a bipolar half sine wave, or a bipolar type trapezoidal wave.

With the above scheme, the output signals of the first pulse signal output end and the second pulse signal output end can be adjusted, and a combination of a plurality of large magnetic moment emission waves and small magnetic moment emission waves can be realized for different application scenarios, and a large magnetic moment The magnetic field is compensated to maintain the constant magnetic field of the large magnetic moment in the flat-top stage; the detection period is shortened to improve the transmission frequency and system operating efficiency.

Still further, the second excitation field transition slope can be increased. The second excitation field transition slope may be increased to be greater than the slope of the first excitation field.

By adopting the above scheme, by changing the clamp voltage, the detection detection period can be adjusted, and the second excitation field turn-on and turn-off time is greatly shortened, and the detection frequency and the detection efficiency can be improved.

Still further, the turns ratio of the primary transmit coil to the secondary transmit coil is: X: 1, where X is greater than or equal to one.

Still further, a receiving coil module is disposed at an edge of the main transmitting coil, the two portions are partially intersected, and the receiving coil module is composed of n receiving coils, and a partial orthographic projection of the main transmitting coil coincides with a partial orthographic projection of the receiving coil module.

The above scheme is adopted to cancel the mutual inductance effect between the main transmitting coil and the receiving coil, thereby eliminating the influence of the excitation primary field generated by the emission control system, and eliminating the phenomenon that multiple magnetic fields are mixed between the main transmitting coil and the receiving coil.

The invention has the beneficial effects that the deep and shallow layers can be detected by the device. In the deep detection, the main transmitting coil and the transmitting coil simultaneously act, and the transmitting coil can compensate the first excitation field emitted by the main transmitting coil, so that the excitation magnetic field is kept constant in the flat top stage when the first half period is maintained. When shallow detection is implemented in the second half cycle, the second excitation field is emitted from the transmitting coil, which can increase the steepness of the falling edge of the second excitation field, improve the shallow detection effect, and shorten the detection period. The whole device is light and flexible, convenient to use, high in resolution, simple in circuit structure, small in loss and good in mobility; the receiving coil is disposed at the edge of the main transmitting coil, which cancels the mutual inductance between the main transmitting coil and the receiving coil, and achieves Eliminate hair The purpose of the excitation control system to generate the primary field influence eliminates the phenomenon of multiple magnetic field aliasing between the main transmitting coil and the receiving coil, reduces the interference during the exploration process, and improves the accuracy of the survey.

DRAWINGS

Figure 1 is a block diagram of the system of the present invention;

Figure 2 is a circuit diagram of the system of the present invention;

3 is a schematic diagram of a first equivalent current of a transmitting coil of the present invention;

4 is a schematic diagram of a second equivalent current of the transmitting coil of the present invention;

Figure 5 is a diagram showing the compensation effect of the present invention from the transmitting coil to the main transmitting coil;

Figure 6 is a schematic diagram of the integrated transmission and reception survey system of the present invention.

Detailed ways

The specific embodiments and working principles of the present invention will be further described in detail below with reference to the accompanying drawings.

As can be seen from Fig. 1, a two-coil coupled multi-wave survey system includes a launch control system, a first set of pulse signal output ends of the launch control system is connected with a main transmit coil, and a second set of pulses of the launch control system A slave transmit coil is connected to the signal output end, the main transmit coil and the slave transmit coil are coupled coils, the main transmit coil and the slave transmit coil are overlapped, and the magnetic fields generated by the two are enhanced; the emission control system is used to generate continuous or intermittent double The polar chopping pulse signal, the main transmitting coil emits a first excitation field in a first transmitting half cycle, and the second excitation field is emitted from the transmitting coil in a second transmitting half cycle.

The first excitation field is compensated from the transmit coil for the first excitation half period to compensate for the excitation field.

The excitation intensity of the first excitation field is greater than the excitation intensity of the second excitation field. The emission control system includes a synchronization controller, a first transmitting circuit and a second transmitting circuit, and the power terminal of the synchronous controller is connected to the transmitting power source;

The second excitation field jump slope can be increased. In this embodiment, the second excitation field transition slope is greater than the slope of the first excitation field.

As can also be seen from FIG. 1, preferably, the first transmitting circuit and the second transmitting circuit are controlled by a synchronous controller to share a set of power supplies.

As can be seen from FIG. 2, preferably, the first transmitting circuit and the second transmitting circuit are identical in structure, and both are H-bridge circuits;

It can be seen from FIG. 6 that a receiving coil module is disposed at the edge of the main transmitting coil, the two parts are partially overlapped, and the receiving coil module is composed of n receiving coils, and part of the orthographic projection of the main transmitting coil and a partial orthographic projection of the receiving coil module Coincidentally, one end of the receiving coil module is connected to the positive input end of the signal conditioning circuit, the other end of the receiving coil module is connected to the reference end of the signal conditioning circuit, and the output end of the signal conditioning circuit is connected to the positive input end of the receiver, the receiver The common reference terminal is connected to the reference terminal of the signal conditioning circuit.

Wherein, the n receiving coils may be n independent working coils, and the n receiving coils may be sequentially connected in series; may be a strip coil, the strip coil is annular and arranged around the edge of the main transmitting coil, both parts At the intersection, a partial orthographic projection of the main transmitting coil coincides with a partial orthographic projection of the strip coil. In the present embodiment, n = 1 or n = 2a, where a is a positive integer to facilitate receiving coil adjustment. As can be seen from Figure 6, there are a total of six receiving coils.

In the exploration process, in order to offset the mutual inductance between the main transmitting coil and the receiving coil, the purpose of eliminating the influence of the primary field generated by the emission control system is eliminated, and the phenomenon of overlapping multiple magnetic fields between the main transmitting coil and the receiving coil is eliminated. The position of the six receiving coils is adjusted to change the overlap between the main transmitting coil and the receiving coil so that the magnetic flux of the main transmitting coil passing through the six receiving coils is zero.

The specific exploration method is:

S1: starting the emission control system, and applying current i(t) to the main transmitting coil;

S2: calculated m-th receiving coil of the primary field flux _{ψ m1 (m = 1,2, ...} , n)

among them:

N ₁ : the total number of turns of the main transmitting coil;

N _m : total number of turns of the mth receiving coil; the structural plan specification should be supplemented, each coil can be single or multiple

k: summation variable of the main transmitting coil;

i: a summation variable of the mth receiving coil;

μ ₀ : vacuum permeability, μ ₀ = 4π × 10 ^-7 H / m;

i(t): the current through which the main transmitting coil passes;

θ _mki : the angle between the i-th coil plane of the mth receiving coil and the normal direction of the kth turn coil of the main transmitting coil;

l _1k : the path of the kth coil of the main transmitting coil;

a line element vector on the kth coil of the main transmitting coil;

The mth receiving coil, the i-th coil plane, and the transmitting coil 1, the kth coil element vector

Relative position vector

R _mki : the mth receiving coil, the i-th coil plane, and the transmitting coil 1, the kth coil element vector

a module of relative position vectors;

s _mi : the plane range of the mth coil of the mth receiving coil;

a plane bin vector of the i-th coil of the mth receiving coil;

S3: adjusting the size of the n receiving coils and the relative position of the main transmitting coil to make the first field magnetic flux of the mth receiving coil;

S4: Calculate the magnetic flux ψ _m2 (m=1, 2..., n) passing through the mth receiving coil under the action of the secondary field:

among them:

B(t): secondary field magnetic induction;

s _mi : the area of the i-th coil of the mth receiving coil;

α _mi : the angle between the normal direction of the ith coil of the receiving coil m and the direction of the secondary field magnetic induction intensity;

S5: calculating the induced voltage of the mth receiving coil

among them:

a field induced voltage between the start and end points of the mth receiving coil;

a secondary field induced voltage between the start and end points of the mth receiving coil;

S6: Combining step S4 to obtain ψ _m1 =0, the induced voltage of the n receiving coils

for:

Example 1:

The parameters of the main transmitting coil and the transmitting coil are:

The main transmitting coil and the transmitting coil are both single-loop cross-linked polyethylene copper core power cables.

The main transmitting coil 4匝, the copper core power cable cross-sectional area is 80mm ² , the coil radius is 17.5m, the inductance is 3mH, and the resistance is 0.125Ω.

From the transmitting coil 1匝, the copper core power cable has a cross-sectional area of 20 mm ² , a coil radius of 17.5 m, an inductance of 0.26 mH, and a resistance of 0.185 Ω.

When a large magnetic moment is emitted:

The main transmitting coil and the transmitting transmitting coil jointly synthesize the emission, and the main transmitting coil and the pulse waveform received from the transmitting transmitting coil are in the shape of a bipolar trapezoidal pulse, linearly rising and linearly decreasing.

As can be seen from Figure 3, the specific parameters are:

Peak magnetic moment: 1300000 Am2, equivalent to 4匝330A. Flat top wave: 1%. Rise time: 1ms. Fall time: 1ms. Flat top width: 5ms. Large magnetic moment half wave: 17ms.

When a small magnetic moment is emitted:

It is emitted separately from the transmitting coil, and the shape of the pulse waveform received from the transmitting coil is a bipolar trapezoidal pulse, which rises linearly and decreases linearly.

As can be seen from Figure 3, the specific parameters are:

Peak magnetic moment: 62,500 Am2, equivalent single-turn 65A, equivalent to 4匝16A. Flat top wave: 3%. Rise time: 13μs. Fall time: 12μs. Flat top width: 5ms. Small magnetic moment half wave: 13ms.

In this embodiment, if each bipolar large magnetic moment wave and bipolar small magnetic moment wave are called a period, the frequency is 33 Hz; if a bipolar large magnetic moment wave and bipolar small magnetic The moment wave is a period, which can be derived from Figure 3, and the frequency is 16.5 Hz.

Example 2:

The parameter settings of the main transmitting coil and the transmitting coil are the same as in the first embodiment.

When a large magnetic moment is emitted:

The main transmitting coil and the transmitting transmitting coil jointly synthesize the emission, and the main transmitting coil passes the bipolar trapezoidal pulse current, and the bipolar triangular wave current is passed from the transmitting coil. The current from the transmitting coil is controlled to achieve a constant power of the first excitation field, and the compensation effect diagram is shown in FIG. 5.

As can be seen from Figure 4, the specific parameters are:

Peak magnetic moment: 1300,000 Am2, equivalent to 4匝330A. Flat top wave: 1%. Rise time: 1ms. Fall time: 1ms. Flat top width: 5ms. Large magnetic moment half wave: 17ms.

When a small magnetic moment is emitted:

It is emitted separately from the transmitting coil, and the waveform shape of the transmitting coil is a bipolar triangular wave pulse.

As can be seen from Figure 4, the specific parameters are:

Peak magnetic moment: 62,500 Am2, equivalent single-turn 65A, equivalent to 4匝16A. Rise time: 12μs. Fall time: 12μs. Small magnetic moment half wave: 8ms.

Comparing Embodiment 1 and Embodiment 2, when a bipolar triangular wave pulse is used from the waveform shape of the transmitting coil, the period is significantly shortened, and the transmission frequency can be improved by using a small magnetic moment to emit a wave as a triangular wave. The disadvantage is that the peak power of the small magnetic moment must be increased to increase the cable radius.

According to the solution proposed by the invention, the main and slave transmitting coils realize large magnetic moment emission, and the transmitting coil realizes small magnetic moment emission. Has the following characteristics:

1, can achieve large depth detection: small magnetic moment launch off delay is very short, improve the shallow detection effect; large magnetic moment emission increases the detection depth, solving the difficult problem of deep and shallow.

2. Double-pulse coupled transmission: adopts dual-transmission coil structure. When large magnetic moment is transmitted, the primary and secondary transmitting coils are synchronously transmitted, which improves the utilization of the transmitting coil. When the small magnetic moment is transmitted independently from the transmitting coil, the coil self-inductance is reduced. Increase the descent steepness and improve the shallow detection effect; when the large magnetic moment is transmitted, the emission control system works at full load, and the transmission coil compensates the stability of the main emission current flat-top magnetic field, which can reduce the power consumption of the emission control system; The control system of the transmitting coil operates in a high-frequency modulation mode, and the current is relatively small, which can reduce power consumption and improve the stability of the magnetic moment;

3, high-speed shutdown of large magnetic moments, small magnetic moments have achieved high-speed shutdown; small magnetic moments use independent small number of coils, shut off more steep, shorter time.

4. The mutual inductance between the main transmitting coil and the receiving coil is cancelled, and the purpose of eliminating the primary field generated by the emission control system is eliminated, and the phenomenon of magnetic field aliasing between the main transmitting coil and the receiving coil is eliminated.

It should be noted that the above description is not intended to limit the invention, and the invention is not limited to the above examples, and variations, modifications, additions or substitutions made by those skilled in the art within the scope of the invention, It should also fall within the scope of protection of the present invention.

Claims

A dual coil coupled multi-wave survey system, comprising: a launch control system, a first transmit pulse output end of the transmit control system is connected with a main transmit coil, and a second set of the launch control system a slave transmit coil is connected to the output end of the pulse signal, the master transmit coil and the slave transmit coil are coupled coils, the primary transmit coil and the slave transmit coil are overlapped, and the magnetic fields generated by the two are enhanced; The emission control system is operative to generate a continuous or intermittent bipolar chopping pulse signal, the primary transmit coil transmitting a first excitation field during a first transmit half cycle and a second excitation field from a transmit coil during a second transmit half cycle.
The dual coil coupled multi-wave survey system of claim 1 wherein said slave transmit coil transmits a first excitation field compensation excitation field during a first transmit half cycle.
The dual coil coupled multi-wave survey system according to claim 1, wherein the excitation intensity of the first excitation field is greater than the excitation intensity of the second excitation field.
The dual-coil coupled multi-wave survey system according to claim 1, wherein the emission control system comprises a synchronization controller, a first transmitting circuit and a second transmitting circuit, and the power terminal of the synchronous controller Transmitting power connection;

The first transmitting circuit is connected to the first group of control outputs of the synchronous controller, and the main transmitting coil is connected to the first group of pulse signal output ends of the first transmitting circuit;

The second transmitting circuit is connected to the second group of control outputs of the synchronous controller, and the slave transmitting coil is connected to the second group of pulse signal output ends of the second transmitting circuit.
The dual-coil coupled multi-wave survey system according to claim 1 or 4, wherein the first transmitting circuit and the second transmitting circuit are identical in structure, and each is an H-bridge circuit;

The four control ends of the first transmitting circuit are respectively connected to the first group of control outputs of the synchronous controller, and the power input end of the first transmitting circuit is connected to the first group of power output ends of the transmitting power source;

The four control ends of the second transmitting circuit are respectively connected to the second group control output end of the synchronous controller, and the power input end of the second transmitting circuit is connected to the second group power output end of the transmitting power source.
The dual-coil coupled multi-wave survey system according to claim 1, wherein the output signal of the first pulse signal output end of the emission control system is a bipolar trapezoidal wave or a bipolar half sine wave, Or a bipolar trapezoidal wave, or a bipolar triangular wave;

The bipolar chopping pulse signal outputted by the second pulse signal output end of the emission control system is a bipolar trapezoidal wave, or a bipolar triangular wave, or a bipolar half sine wave, or a bipolar type trapezoidal wave.
The dual coil coupled multi-wave survey system of claim 6 wherein said second excitation field transition slope is increased.
The dual-coil coupled multi-wave survey system according to claim 1, wherein a ratio of turns of the main transmitting coil and the transmitting coil is: X:1.
The dual-coil coupled multi-wave survey system according to claim 1, wherein a receiving coil module is disposed at an edge of the main transmitting coil, the two portions are partially intersected, and the receiving coil module is received by n The coil is composed of a partial orthographic projection of the primary transmitting coil that coincides with a partial orthographic projection of the receiving coil module.