A flux superposition primary field cancellation electromagnetic device and method

Abstract

This application belongs to the field of geophysical exploration technology, specifically disclosing an electromagnetic device and method for primary field cancellation through magnetic flux superposition. A first transmitter drives a transmitting coil to generate a primary field; a second transmitter drives a compensation coil with a current in the same direction, generating a compensation magnetic flux with opposite phase and amplitude to the transmitting coil, achieving local cancellation of the primary field. Since the current directions of the transmitting and compensation coils are consistent, the receiving coil measures the magnetic field response after superposition and compensation, using a higher secondary field signal to monitor the geological information contained in underground anomalies. The unknown geometric parameters and spatial positions of the transmitting and compensation coils are used to calculate the total magnetic flux generated by the transmitting and compensation coils in the receiving area using the Biot-Savart law, aiming to determine the magnetically quiet zone for primary field cancellation and evaluating the cancellation effect. This application achieves primary field cancellation on the receiving side, improving the signal strength and detectability of the secondary field.

Description

Technical Field

[0001] This application belongs to the field of geophysical exploration technology, and more specifically, relates to an electromagnetic device and method for primary field cancellation of magnetic flux superposition. Background Technology

[0002] Electromagnetic methods are a class of techniques that use a transmitter to excite a known electromagnetic field (primary field) and detect the secondary response (secondary field) generated by the medium or target under this excitation to detect underground or inspected objects. They are widely used in geophysical exploration, archaeology, environmental surveys, and non-destructive testing. Time-domain electromagnetic methods (TDEM) generate a transient primary field using pulsed or step excitation. Eddy currents are induced in a conductor by changes in magnetic flux caused by the excitation switch. The receiver records the transient secondary field, which decays over time, to infer the target's conductivity, size, and depth. Frequency-domain electromagnetic methods (FDEM) generate a steady-state primary field using single-frequency or multi-frequency sinusoidal excitation. Secondary field information related to the target's electromagnetic properties is obtained by measuring the amplitude and phase spectrum at the receiver. Frequency dependence reflects responses at different depths and physical properties. The primary field is a known strong background, directly generated by the transmitting system, and has a large amplitude; the secondary field is generated by the induced response of the underground body or target to the primary field, has a smaller amplitude but contains key target information.

[0003] In practical applications, the amplitude of the primary field is usually much larger than that of the secondary field, and its spatial distribution is complex, which poses a significant challenge to the detection and extraction of the secondary field. Especially in near-field measurement or scenarios with weak response targets (such as small-volume conductors, shallowly buried targets, or components with low magnetic contrast), the primary field directly coupled to the receiver can mask the secondary field signal, leading to a decrease in signal-to-noise ratio, reduced positioning accuracy, and an increased false positive rate. To address this, signal processing methods such as differential reception, synchronous demodulation, frequency domain filtering, polarization measurement, multi-point measurement, and matrix decomposition are commonly used to suppress the primary field component. However, these methods remain limited in complex environments (with strong magnetic interference, conductive bodies, or multi-target coupling).

[0004] Furthermore, to reduce the direct coupling of the primary field at the receiver, passive cancellation is often employed in existing technologies. Passive cancellation achieves partial or complete geometric cancellation of the primary field from the transmitter at the receiving position through vector superposition by designing the receiver or transmitter-receiver geometry and special winding structures (such as differential windings, compensating coils, mirrored coil arrays, or reverse windings). For example, the typical dual-channel receiver structure (see CN118915165A) and anti-flux device in instruments such as GEM-2 can effectively cancel the primary field. However, they also have certain shortcomings: when using only a single transmitter, the transmitted signal of this method will be relatively small, so the generated secondary field (including the response generated by underground conductors or electrical anomalies) will also be weakened accordingly, which directly affects the detection sensitivity, positioning and quantitative interpretation capabilities, and increases the difficulty of measurement and processing. Correspondingly, although the anti-magnetic flux device uses dual emission sources (see CN121254367A, CN120276049A), this anti-phase emission reduces the primary field coupling while being partially canceled out by the secondary field generated by the target. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide a primary field cancellation electromagnetic device and method for magnetic flux superposition, which aims to solve the problem that the primary field in the existing electromagnetic method will couple to the receiver and mask the secondary field signal, resulting in a decrease in the signal-to-noise ratio of the secondary field, a decrease in positioning accuracy, and an increase in the false judgment rate.

[0006] The first aspect of this application relates to a primary field cancellation electromagnetic device for magnetic flux superposition, comprising: a first transmitter, a second transmitter, a receiver, a transmitting coil, a compensation coil, and a receiving coil; the receiving coil is located inside the compensation coil; the currents in the transmitting coil and the compensation coil are in the same direction to enhance the secondary field; The first transmitter is used to drive the transmitting coil to generate a primary field; the second transmitter is used to drive the compensation coil to generate a compensation magnetic flux with the opposite phase and amplitude to the transmitting coil, which superimposes and compensates the primary field to achieve local cancellation of the primary field; the receiver is connected to the receiving coil and is used to measure the magnetic field response after superposition and compensation in order to monitor the geological information contained in the underground anomaly. The unknown geometric parameters and unknown spatial position parameters of the transmitting coil, compensation coil and receiving coil are used to calculate the total magnetic flux generated by the transmitting coil and compensation coil in the receiving region using the Biot-Savart law. The magnetic quiet region that provides primary field cancellation for the receiving coil is determined as the target, and the primary field cancellation effect is evaluated by simulation.

[0007] In some implementations, the transmitting coil, the compensation coil, and the receiving coil are coplanar coil structures.

[0008] In some implementations, the geometric parameters of the transmitting coil, the compensating coil, and the receiving coil include the current magnitude and the number of coil turns; the spatial location includes the coil shape and the coil position.

[0009] In some implementations, the transmitting coil, the compensation coil, and the receiving coil are circular coils.

[0010] The second aspect of this application relates to a primary field cancellation electromagnetic method for magnetic flux superposition, comprising the following steps: Step S1: Based on the principle of electromagnetic field superposition and according to the Biot-Savart law, taking the magnetic field strength at a single point as the benchmark, and deducing step by step from line integral to surface integral, calculate the total magnetic flux generated by the transmitting coil and the compensation coil in the receiving area. With the goal of providing a magnetically quiet region for primary field cancellation for the receiving coil, globally optimize the unknown geometric parameters and unknown spatial position parameters of the transmitting coil, compensation coil and receiving coil. Step S2: Construct a three-dimensional electromagnetic field finite element model, set the geometric parameters and spatial position parameters of the transmitting coil, compensation coil, and receiving coil, draw the field distribution diagram to obtain the cancellation effect, and evaluate the primary field cancellation factor by using the voltage magnitude of the receiving coil.

[0011] In some implementations, step S2 specifically includes the following steps: Step S2.1: Construct a three-dimensional electromagnetic field finite element model to determine the location range of the air domain and the multi-layer underground medium, as well as their corresponding electromagnetic properties; Step S2.2: Model the transmitting coil, compensation coil and receiving coil on the three-dimensional electromagnetic field finite element model, and set the spatial position parameters and geometric parameters of the transmitting coil, compensation coil and receiving coil. Use the infinite element domain as the boundary condition, and then perform tetrahedral meshing on the three-dimensional electromagnetic field finite element model. Step S2.3: In the three-dimensional electromagnetic field finite element model after tetrahedral meshing, change the spatial positions of the receiving coil and the compensation coil to verify convergence, draw the electromagnetic field and magnetic flux density modulus distribution diagram, obtain the primary field cancellation effect, and evaluate the primary field cancellation factor by using the voltage of the receiving coil.

[0012] In some implementations, the geometric parameters of the transmitting coil, the compensating coil, and the receiving coil include the current magnitude and the number of coil turns, and the spatial location includes the coil shape and the coil position.

[0013] In some implementations, if the transmitting coil, compensation coil, and receiving coil are circular coils, then step S1 specifically includes the following steps: Determine the transmitting current of the compensation coil, the center coordinates, radius, and transmitting current of the transmitting coil, as well as the center coordinates, radius, and number of turns of the receiving coil; Based on the principle of electromagnetic field superposition and according to the Biot-Savart law, using the magnetic field strength at a single point as a reference, and deducing step by step from line integral to area integral, the total magnetic flux generated by the transmitting coil and the compensation coil in the receiving area is calculated. With the goal of providing a magnetically quiet region for primary field cancellation of the receiving coil, the number of turns of the transmitting coil, the number of turns of the compensation coil, the center coordinates of the compensation coil, and the radius of the compensation coil are globally optimized.

[0014] Thirdly, this application provides an electronic device, comprising: at least one memory for storing a program; and at least one processor for executing the program stored in the memory, wherein when the program stored in the memory is executed, the processor is configured to execute the method described in the first aspect or any possible implementation thereof.

[0015] Fourthly, this application provides a computer-readable storage medium storing a computer program that, when run on a processor, causes the processor to perform the method described in the first aspect or any possible implementation thereof.

[0016] Fifthly, this application provides a computer program product that, when run on a processor, causes the processor to perform the method described in the first aspect or any possible implementation thereof.

[0017] It is understood that the beneficial effects of the second to fifth aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here.

[0018] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art: This application provides a primary field cancellation electromagnetic device with magnetic flux superposition. The coil structure is a dual-emitting and unidirectional coil structure. By optimizing the current magnitude, number of coil turns and geometric layout, complementary magnetic flux distributions are generated by different coils or coil groups, achieving spatial or vector-level cancellation of the primary field on the receiving side, thereby improving the detectability of the secondary field at the hardware level.

[0019] This application provides a primary field cancellation electromagnetic device based on magnetic flux superposition. The unknown geometric parameters and unknown spatial positions of the transmitting coil and the compensation coil are used to calculate the total magnetic flux generated by the transmitting coil and the compensation coil in the receiving area using the Biot-Savart law. The target is to determine the magnetically quiet zone that provides primary field cancellation for the receiving coil. At the receiving side, the device simultaneously achieves the goal of significantly suppressing primary field coupling and enhancing the detectability of the target's secondary field. This allows for adaptive matching to different operating conditions without changing the physical components, significantly improving field adaptability and engineering feasibility. This method can improve the detection sensitivity and spatial resolution of shallow and deep weak response targets, reduce the dependence on complex back-end signal processing and spatial differential algorithms, simplify system integration, and enhance anti-interference capabilities. Attached Figure Description

[0020] Figure 1 This is a schematic diagram showing the relationship and specific magnetic flux between the transmitting coil, the compensation coil, and the receiving coil provided in the embodiments of this application.

[0021] Figure 2 This is a schematic flowchart of the electromagnetic method for primary field cancellation by magnetic flux superposition provided in the embodiments of this application.

[0022] Figure 3 This is a schematic diagram of the magnetic field distribution provided in the embodiments of this application.

[0023] Figure 4 This is a schematic diagram of a primary field cancellation electromagnetic device for magnetic flux superposition provided in an embodiment of this application.

[0024] Figure 5 This is a schematic diagram of the field cancellation effect provided in an embodiment of this application.

[0025] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1 is the first transmitter; 2 is the second transmitter; 3 is the receiver; 4 is the transmitting coil; 5 is the compensation coil; 6 is the receiving coil; 7 is the first connection; 8 is the second connection; 9 is the third connection. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0027] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. In this application, the symbol " / " indicates that the related objects are in an "or" relationship, for example, A / B means A or B.

[0028] In this application, the terms “first” and “second” are used to distinguish different objects, rather than to describe a specific order of objects.

[0029] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0030] In the description of the embodiments in this application, unless otherwise stated, "multiple" means two or more.

[0031] The embodiments of this application are described below with reference to the accompanying drawings.

[0032] This application provides a primary field cancellation electromagnetic device based on magnetic flux superposition to improve the detection sensitivity and anti-interference capability of weak-response targets. This application employs a dual-transmitting, unidirectional coil structure. By designing the current magnitude, number of turns, and geometric layout of the transmitting and compensating coils, as well as the number of turns and geometric layout of the receiving coil (wherein the geometric layout includes coil shape and coil position), complementary magnetic flux distributions are generated between different coils or coil groups. This achieves spatial or vector-level cancellation of the primary field on the receiving side, thereby improving the detectability of the secondary field at the hardware level.

[0033] like Figure 1 As shown, this application provides a primary field cancellation electromagnetic device for magnetic flux superposition, including a transmitting coil, a compensation coil, and a receiving coil; the receiving coil is located inside the compensation coil; the currents in the transmitting coil and the compensation coil are in the same direction; a first transmitter is used to drive the transmitting coil to generate a primary field; a second transmitter is used to drive the compensation coil to generate a compensation magnetic flux with the opposite phase and amplitude to the transmitting coil, thereby superimposing and compensating the primary field to achieve local cancellation of the primary field; the receiver is connected to the receiving coil and is used to measure the magnetic field response after superposition and compensation to monitor the geological information contained in the underground anomaly; wherein, the geometric parameters and spatial positions of the transmitting coil and the compensation coil are calculated using the Biot-Savart law to determine the total magnetic flux generated by the transmitting coil and the compensation coil in the receiving area, with the goal of providing a magnetically quiet zone for primary field cancellation of the receiving coil, and the effect of primary field cancellation is evaluated using COMSOL simulation.

[0034] A more detailed explanation of the principle of field cancellation is as follows: Figure 1The large blue rectangle on the left is the transmitting coil. The arrow indicates that the current direction is clockwise. It is the excitation source in electromagnetic methods. A known alternating current or transient current is typically passed through it to generate a controllable spatial magnetic field. This excitation determines the detection depth, frequency response, and spatial distribution of the field, and influences the strength and phase of the received signal through coupling with the secondary field generated by the underground body. Using the right-hand rule, this coil will generate a magnetic field perpendicular to the plane inward in the central region and a magnetic field perpendicular to the plane outward in the outer region (as shown by the blue dot and blue...). (As shown); the red outer rectangle on the right is the compensation coil (the current direction is also clockwise). Its parameters can be adjusted to cancel or balance the excess far-field components of the transmitting coil in the receiving area, thereby creating the desired magnetic field distribution in the target area. The red dots in the diagram are... These represent the different directions of the magnetic field generated by the compensation coil inside and outside the central region. In summary, it can be observed that the receiving coil will simultaneously receive the opposite effects generated by the transmitting and compensation coils. As long as the coil parameters are reasonably controlled so that the magnetic flux generated by the transmitting coil in the receiving coil is infinitely close to the magnetic flux generated by the compensation coil in the receiving coil, a local magnetically quiet region can be formed in the receiving region.

[0035] like Figure 2 As shown, this application provides a method for canceling electromagnetic fields by superimposing magnetic flux, comprising the following steps: Step S1: Based on the principle of electromagnetic field superposition and according to the Biot-Savart law, taking the magnetic field strength at a single point as the benchmark, and deducing step by step from line integral to surface integral, calculate the total magnetic flux generated by the transmitting coil and the compensation coil in the receiving area. With the goal of providing a magnetically quiet region for primary field cancellation for the receiving coil, globally optimize the unknown geometric parameters and unknown spatial position parameters of the transmitting coil, compensation coil and receiving coil. Step S2: Construct a three-dimensional electromagnetic field finite element model, set the geometric parameters and spatial position parameters of the transmitting coil, compensation coil and receiving coil obtained in step S1, draw the field distribution diagram to obtain the cancellation effect, and at the same time use the voltage of the receiving coil to evaluate the primary field cancellation factor.

[0036] Specifically, such as Figure 2 As shown, this application proposes a coil scheme optimization method (step S1) and a finite element-based numerical verification process (step S2). The coil scheme optimization method involves globally optimizing the geometric parameters and spatial position of the coil, aiming to provide a magnetically quiet region where the primary field is almost canceled at the receiving coil. Several preferred implementation methods are then given to achieve the synergistic goal of primary field cancellation and secondary field enhancement.

[0037] The theoretical basis of this method is derived from the principle of electromagnetic field superposition. Based on the Biot-Savart law, starting from the magnetic field strength at a single point, the total magnetic flux generated by the transmitting coil and the compensation coil in the receiving area can be accurately calculated step by step from the line integral to the area integral, thus providing a quantitative basis for the accurate cancellation of the primary field.

[0038] According to the Biot-Savart Law, the current element... The magnetic induction intensity generated at a point P in space Size and current element The magnitude of the current element is directly proportional to the sine of the angle between the position vector from the current element to point P and the current element, and inversely proportional to the square of the distance from the current element to point P.

[0039]

[0040]

[0041] Where I is the source current and L is the integration path; The length of the infinitesimal current element; It is the unit vector from the current element to the point of the field to be determined; Permeability of free space; Let be the position vector of the current element pointing to the field point P.

[0042] If there is a point P next to a straight current of finite length, at a distance a from the straight current, and we establish a coordinate system Oxy, with the current element on the y-axis being Idy, we can calculate the magnetic field strength generated at point P. for: ; Finally, after sorting through the information, we can obtain: ; Where b and c are the upper and lower limit coordinate values ​​when integrating over a finite-length straight line; y is the variable position along the y-axis; and dy is the infinitesimal increment of y. and In the geometric relationship between a finite-length straight conductor and a field point P, let be the angles from the lower end to P respectively. ), and the angle from the top to P ( ).

[0043] Based on the above formula derivation, this application has entered the theory-simulation cross-validation stage. Its core purpose is to rigorously verify whether the coil configuration generated by the coil scheme optimization method can achieve the same precise cancellation of the magnetic field in the COMSOL finite element model.

[0044] The data simulation verification using COMSOL includes the following steps: Step S2.1: Construct a three-dimensional electromagnetic field finite element model to determine the location range of the air domain and the multi-layer underground medium, as well as their corresponding electromagnetic properties; Step S2.2: Model the transmitting coil, compensation coil and receiving coil on the three-dimensional electromagnetic field finite element model, and set the spatial position parameters and geometric parameters of the transmitting coil, compensation coil and receiving coil. Use the infinite element domain as the boundary condition, and then perform tetrahedral meshing on the three-dimensional electromagnetic field finite element model. Step S2.3: In the three-dimensional electromagnetic field finite element model after tetrahedral meshing, change the spatial positions of the receiving coil and the compensation coil to verify convergence, draw electromagnetic field and magnetic flux density modulus distribution diagrams to obtain the cancellation effect, and at the same time use the voltage of the receiving coil to evaluate the primary field cancellation factor.

[0045] To ensure the systematic nature and reliability of the verification process, a step-by-step approach was adopted, starting with the simplest elements and progressing to more complex ones. The verification work began with the most basic electromagnetic unit—a single long straight conductor. The magnetic field strength generated by this conductor at a specific point in space was used as the initial benchmark for verification, and the simulation results from COMSOL were compared with the theoretical calculations. Subsequently, the spatial dimension of the verification increased for the first time: the focus was expanded from an isolated point to a two-dimensional plane. By comparing the two-dimensional magnetic field distribution diagram generated by the long straight conductor on this plane, the consistency between theory and simulation over a broader spatial range was confirmed.

[0046] The comparison shows that the relative errors of the two are approximately 2.03% and 1.94%, respectively. These are small errors below the threshold of conventional engineering and are mainly due to the inherent discrete errors of finite element calculations and the idealized assumptions of the model, which are completely within the acceptable range.

[0047] After establishing the foundation for the unit components, the verification work moved on to verifying the actual coil system: a rectangular coil consisting of four long straight conductors was constructed, extending the analysis scope to a two-dimensional cross-section to evaluate its two-dimensional magnetic field distribution. Calculations showed that the relative error at this stage was approximately 4.77%.

[0048] This series of rigorous comparisons, progressively increasing the model complexity, confirmed that the optimization results based on theoretical formulas and the simulation results from COMSOL exhibited a high degree of consistency throughout the verification sequence. Whether it was the magnetic field strength at a single point or the spatial distribution of the magnetic field in a two-dimensional plane, the relative errors between the two remained stable within the preset acceptable range.

[0049] Based on the above theoretical foundation and its verification, the coil scheme optimization method uses known partial coil parameters as constraints to find all unknown parameters of the transmitting, compensating and receiving coils, thereby creating a "magnetic quiet zone" in the receiving coil where the primary field is almost completely canceled.

[0050] Therefore, we can conclude that the coil optimization method presented here can reliably guide coil design, successfully creating a "magnetic quiet zone" in the target area where the primary field is almost completely canceled, such as... Figure 3 As shown, this lays a solid and reliable foundation for the subsequent introduction of underground anomalies, the study of secondary field signals, and ultimately, a comprehensive improvement in the system's detection performance. Example 1 like Figure 4 As shown, this application provides a primary field cancellation electromagnetic device for magnetic flux superposition, including a first transmitter 1, a second transmitter 2, a receiver 3, a transmitting coil 4, a compensation coil 5, and a receiving coil 6; The first transmitter 1 drives the transmitting coil 4 through the first connection 7, and the second transmitter 2 drives the compensation coil 5 through the second connection 8 to generate a compensation magnetic flux with the opposite phase and amplitude to the transmitting coil to achieve local cancellation of the primary field; the receiver 3 is connected to the receiving coil 6 through the third connection 9 to measure the magnetic field response after superposition and compensation and to monitor the geological information contained in the underground anomaly. The entire arrangement achieves the required magnetic flux superposition and primary field suppression by adjusting the parameters of the transmitting coil and the compensation coil. More preferably, the three coils are coplanar coil structures. The main advantages of coplanar coil structures compared to non-coplanar devices are: the geometric position makes primary field cancellation more stable, the structure is compact and easy to install, calibrate and array, and the additional coupling and terrain errors caused by height differences are reduced, thereby improving anti-interference ability. This is because it significantly reduces primary field residue, improves the signal-to-noise ratio and spatial resolution of the receiving coil to the secondary response, and simplifies the electromagnetic simulation and inversion process.

[0051] More preferably, the geometric parameters and spatial positions of the transmitting coil and the compensation coil are determined by calculating the total magnetic flux generated by the transmitting coil and the compensation coil in the receiving region using the Biot-Savart law, with the goal of providing a magnetically quiet region for primary field cancellation of the receiving coil.

[0052] For example, in an experiment, let's take a circular coil as an example: First, determine the transmitting current of the compensation coil; the center coordinates, radius, and transmitting current of the transmitting coil; and the center coordinates, radius, and number of turns of the receiving coil. Then, use the coil scheme optimization method to iterate and obtain some other parameters that need to be determined, such as the number of turns of the transmitting coil and the number of turns, center coordinates, radius range, etc. of the compensation coil. Finally, the coil parameter references shown in Table 1 can be obtained.

[0053] This method exhibits excellent versatility: in addition to the circular coil example described above, it is also applicable to coils of arbitrary shapes such as rectangles and ellipses. By freely fixing any known parameters (such as the current amplitude, number of turns, position, or size of any coil), the method performs global optimization and local refinement of the remaining unknown variables based on these constraints, outputting the optimal or alternative scheme that satisfies the objectives of primary field cancellation and secondary field enhancement. This process can be seamlessly extended to large-scale engineering deployments or small portable systems, adapting to different working conditions and engineering scales, and possesses good portability and engineering applicability. Simultaneously, this method can improve the detection sensitivity and spatial resolution of shallow and deep weak-response targets, reduce reliance on complex back-end signal processing and spatial differential algorithms, simplify system integration, and enhance anti-interference capabilities.

[0054] Table 1

[0055] Ultimately, this application uses a coil scheme optimization method to determine the specific parameters of each coil and constructs a complete numerical model of the coil system using COMSOL Multiphysics simulation software. The theoretical calculations and optimization results are then physically verified to ensure their feasibility and effectiveness in actual detection scenarios. This is expected to improve signal reception sensitivity to a new order of magnitude. In existing simulation results, the cancellation effect between the primary and secondary fields is as high as approximately 440,562 times (e.g., ...). Figure 5 When only the transmitting coil is working, the voltage of the receiving coil is 5.00e-3V. By adding and adjusting the geometry of the compensation coil, it can be observed that the voltage of the receiving coil can reach as low as 1.14e-8V.

[0056] Among existing electromagnetic methods, towed systems can achieve efficient large-area coverage and high-sensitivity detection at different scales and under various operating conditions, while also offering rapid deployment, real-time data acquisition, and adaptability to multiple scenarios. Overall, development is rapid in terms of equipment modularization, automation, and multi-sensor fusion, and is moving towards higher sensitivity, real-time processing capabilities, and engineering applications. This application can be directly applied to towed electromagnetic methods: on a towed platform, this configuration significantly reduces direct coupling noise between transmission and reception, improves sensitivity and lateral resolution for shallow, medium, and deep weak-response targets, simplifies on-site data processing, and adapts to complex terrain and dynamic operating conditions. Overall, this solution combines versatility and engineering portability, reducing backend processing complexity, improving data quality, and expanding the application value of electromagnetic methods in resource exploration, environmental monitoring, engineering geology, and safety detection.

[0057] It should be understood that expressions such as “comprising” and “may include” used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as “comprising” and / or “having” are to be interpreted as indicating a particular characteristic, number, operation, constituent element, component, or combination thereof, but not to exclude the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0058] Based on the above-described electromagnetic method of primary field cancellation through magnetic flux superposition, this application provides an electronic device that may include a processor, a communication interface, a memory, and a communication bus. The processor, communication interface, and memory communicate with each other via the communication bus. The processor can invoke logical instructions stored in the memory to execute the methods described in the above embodiments.

[0059] Furthermore, the logical instructions in the aforementioned memory can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application.

[0060] Based on the methods in the above embodiments, this application provides a computer-readable storage medium storing a computer program that, when run on a processor, causes the processor to execute the methods in the above embodiments.

[0061] Based on the methods in the above embodiments, this application provides a computer program product that, when run on a processor, causes the processor to execute the methods in the above embodiments.

[0062] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A primary field cancellation electromagnetic device for magnetic flux superposition, characterized in that, include: First transmitter, second transmitter, receiver, transmitting coil, compensation coil, and receiving coil; The receiving coil is located inside the compensation coil; The currents in the transmitting coil and the compensation coil are in the same direction; The first transmitter is used to drive the transmitting coil to generate a primary field; The second transmitter is used to drive the compensation coil to generate a compensation magnetic flux that is opposite in phase and amplitude to the transmitting coil, thereby superimposing compensation on the primary field and achieving local cancellation of the primary field. The receiver is connected to the receiving coil and is used to measure the magnetic field response after superposition and compensation in order to monitor the geological information contained in the underground anomaly. The geometric and spatial position parameters of the transmitting coil, compensation coil, and receiving coil are calculated using the Biot-Savart law to determine the total magnetic flux generated by the transmitting coil and compensation coil in the receiving region. The magnetically quiet region is determined with the goal of providing primary field cancellation for the receiving coil, and the primary field cancellation effect is evaluated using COMSOL simulation. Among them, the transmitting coil, the compensation coil, and the receiving coil are coplanar coil structures; The primary field cancellation electromagnetic method based on a primary field cancellation electromagnetic device includes the following steps: Step S1: Based on the principle of electromagnetic field superposition and according to the Biot-Savart law, taking the magnetic field strength at a single point as the benchmark, and deducing step by step from line integral to surface integral, calculate the total magnetic flux generated by the transmitting coil and the compensation coil in the receiving area. With the goal of providing a magnetically quiet region for primary field cancellation for the receiving coil, globally optimize the unknown geometric parameters and unknown spatial position parameters of the transmitting coil, compensation coil and receiving coil. Step S2: Construct a three-dimensional electromagnetic field finite element model, set the geometric parameters and spatial position parameters of the transmitting coil, compensation coil and receiving coil, draw the field distribution diagram to obtain the cancellation effect, and at the same time use the voltage of the receiving coil to evaluate the primary field cancellation factor; If the transmitting coil, compensation coil, and receiving coil are circular coils, then step S1 specifically includes the following steps: Determine the transmitting current of the compensation coil, the center coordinates, radius, and transmitting current of the transmitting coil, as well as the center coordinates, radius, and number of turns of the receiving coil; Based on the principle of electromagnetic field superposition and according to the Biot-Savart law, using the magnetic field strength at a single point as a reference, and deducing step by step from line integral to area integral, the total magnetic flux generated by the transmitting coil and the compensation coil in the receiving area is calculated. With the goal of providing a magnetically quiet region for primary field cancellation of the receiving coil, the number of turns of the transmitting coil, the number of turns of the compensation coil, the center coordinates of the compensation coil, and the radius of the compensation coil are globally optimized.

2. The primary field cancellation electromagnetic device according to claim 1, characterized in that, The geometric parameters of the transmitting coil, compensation coil, and receiving coil include the current magnitude and the number of coil turns; the spatial position includes the coil shape and the coil location.

3. The primary field cancellation electromagnetic device according to claim 1, characterized in that, Step S2 specifically includes the following steps: Step S2.1: Construct a three-dimensional electromagnetic field finite element model to determine the location range of the air domain and the multi-layer underground medium, as well as their corresponding electromagnetic properties; Step S2.2: Model the transmitting coil, compensation coil and receiving coil on the three-dimensional electromagnetic field finite element model, and set the spatial position parameters and geometric parameters of the transmitting coil, compensation coil and receiving coil. Use the infinite element domain as the boundary condition, and then perform tetrahedral meshing on the three-dimensional electromagnetic field finite element model. Step S2.3: In the three-dimensional electromagnetic field finite element model after tetrahedral meshing, change the spatial positions of the receiving coil and the compensation coil to verify convergence, draw the electromagnetic field and magnetic flux density modulus distribution diagram, obtain the primary field cancellation effect, and evaluate the primary field cancellation factor by using the voltage of the receiving coil.

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