Crosstalk-free guided wave monitoring system

Abstract

The application provides a crosstalk-free guided wave monitoring system, which can be applied to monitoring of a guided wave signal of a health state of a structure fault high incidence area, i.e., a hotspot area. The system eliminates the coupling interference of common mode impedance by setting a separate excitation guided wave module and an isolated signal excitation ground and receiving ground, and then eliminates the coupling interference of a space electromagnetic field by adding a shielding cover to the receiving module, so that the action condition of a crosstalk signal is fundamentally removed, and blind area monitoring of the system on the hotspot area of the structure is realized. Meanwhile, the system can realize multi-channel switching of an excitation channel and a receiving channel, and can complete synchronous monitoring of multiple hotspot areas on a single structure or multiple structures.

Description

Technical Field

[0001] This invention relates to a guided wave monitoring system, and more particularly to a structural health monitoring system based on guided wave and piezoelectric sensor technology. Background Technology

[0002] Structural health monitoring based on ultrasonic guided waves enables online structural condition diagnosis, maintaining the operational safety of aerospace vehicles. Due to the influence of humid and hot environments, vibration and noise, and fatigue loads, hot spots in aerospace vehicles (such as welded surfaces, bolted connections, and adhesive joints) have a high probability of failure, requiring real-time online monitoring. However, the structural forms of hot spots in aerospace vehicles are complex, the monitoring area is limited, and guided waves experience significant signal attenuation in these areas, necessitating a close-range, high-density deployment of piezoelectric sensors. Existing guided wave monitoring hardware systems use piezoelectric sensor units that integrate excitation and reception, but crosstalk issues prevent them from meeting the requirements of practical engineering applications. Summary of the Invention

[0003] One of the purposes of this application is to overcome the shortcomings of the prior art and provide a system to achieve crosstalk-free excitation reception of guided wave signals, eliminate the fault identification blind zone of traditional guided wave equipment, and thus achieve effective health monitoring of structural hotspot areas.

[0004] To this end, some embodiments of this application provide a crosstalk-free guided wave monitoring system, including a guided wave signal excitation module configured to generate an excitation guided wave signal; a guided wave excitation sensor array operably connected to the guided wave signal excitation module, configured to receive the excitation guided wave signal and generate an excitation signal based on the excitation guided wave signal; a guided wave receiving sensor array configured to receive the echo signal of the excitation signal; and a guided wave signal receiving module operably connected to the guided wave receiving sensor array, configured to synchronously acquire the echo signal; wherein, the guided wave signal excitation module is operably connected to a main control module via a first isolation communication unit and is controlled by the main control module to generate the excitation guided wave signal; and the guided wave signal receiving module is operably connected to the main control module via a second isolation communication unit and is controlled by the main control module to synchronously acquire the echo signal.

[0005] In some embodiments, the crosstalk-free guided wave monitoring system has a unified internal ground plane, the main control module is located in the first internal ground plane portion, the guided wave signal excitation module is located in the second internal ground plane portion, and the guided wave signal receiving module is located in the third internal ground plane portion. The first internal ground plane portion, the second internal ground plane portion, and the third internal ground plane portion are not directly electrically connected.

[0006] In some embodiments, the first internal ground plane portion where the main control module is located has a main control ground GND, the second internal ground plane portion where the guided wave signal excitation module is located has an excitation ground SGND, and the third internal ground plane portion where the guided wave signal receiving module is located has a receiving ground RGND, wherein the main control ground GND, the excitation ground SGND, and the receiving ground RGND are isolated from each other.

[0007] In some embodiments, a shielding cover is installed outside the waveguide signal receiving module, which, together with the receiving ground RGND of the printed circuit board's internal electrical layer, forms a complete shielding space to isolate the radiation effect of the spatial electromagnetic field of the waveguide signal transmitting module.

[0008] In some embodiments, the crosstalk-free guided wave monitoring system further includes a power supply module; the guided wave signal excitation module includes a first power supply unit, which is connected to the power supply module through a first isolation power supply unit; the guided wave signal receiving module includes a second power supply unit, which is connected to the power supply module through a second isolation power supply unit.

[0009] In some embodiments, the power supply module is a 220V AC power supply module or a DC power supply module.

[0010] In some embodiments, the first isolated communication unit includes a first input buffer, a first isolation capacitor, and a first output buffer. The first input buffer is configured to convert a logic control signal into a high-frequency AC signal. The first isolation capacitor is configured to couple the high-frequency AC signal to the output terminal of the first isolated communication unit. The first output buffer is configured to restore the high-frequency AC signal to a logic control signal, thereby realizing cross-ground plane isolated transmission of the logic control signal. The input ground GNDI of the first input buffer is isolated from the output ground GNDO of the first output buffer.

[0011] In some embodiments, the second isolated communication unit includes a second input buffer, a second isolation capacitor, and a second output buffer. The second input buffer is configured to convert a logic control signal into a high-frequency AC signal. The second isolation capacitor is configured to couple the high-frequency AC signal to the output terminal of the second isolated communication unit. The second output buffer is configured to restore the high-frequency AC signal to a logic control signal, thereby realizing cross-ground plane isolated transmission of the logic control signal. The input ground GNDI of the second input buffer is isolated from the output ground GNDO of the second output buffer.

[0012] In some embodiments, the first isolated power supply unit includes a first PWM controller, a first power switch, a first transformer, a first rectifier and filter circuit, a first sampling and comparison circuit, and a first isolation feedback circuit. The first PWM controller is configured to control the first power switch to generate a first AC current at the power input terminal of the first isolated power supply unit. The first transformer is configured to couple the first AC current to the output terminal of the first isolated power supply unit and convert it into a first DC power supply through the first rectifier and filter circuit. The output terminal of the first rectifier and filter circuit samples the output voltage of the first DC power supply and compares it with a first reference voltage to obtain a first difference. The first isolation feedback circuit is configured to transmit the first difference to the first PWM controller to form a closed-loop control to stably supply power to the output terminal of the first isolated power supply unit.

[0013] In some embodiments, the second isolated power supply unit includes a second PWM controller, a second power switch, a second transformer, a second rectifier and filter circuit, a second sampling and comparison circuit, and a second isolated feedback circuit. The second PWM controller is configured to control the second power switch to generate a second AC current at the power input terminal. The second transformer is configured to couple the second AC current to the output terminal and convert it into a second DC power supply through the second rectifier and filter circuit. The output terminal of the second rectifier and filter circuit is sampled by the second sampling and comparison circuit, and the output voltage of the second DC power supply is compared with a second reference voltage to obtain a second difference. The second isolated feedback circuit is configured to transmit the second difference to the second PWM controller to form a closed-loop control to stably supply power to the output terminal of the second isolated power supply unit.

[0014] In some embodiments, the guided wave signal excitation module includes a guided wave signal generation unit, a power amplification unit, a first channel switching control unit, and a first relay channel switching matrix. The guided wave signal generation unit receives a control signal from the main control module via the first isolation communication unit to generate the excitation guided wave signal. The power amplification unit is configured to amplify the excitation guided wave signal and send it to the first relay channel switching matrix. The first channel switching control unit is configured to receive a first channel selection control signal from the main control module via the first isolation communication unit to transmit the excitation guided wave signal through the selected channel in the first relay channel switching matrix to the guided wave excitation sensor array operably connected thereto.

[0015] In some embodiments, the guided wave signal receiving module includes a signal buffer conditioning unit, a signal acquisition unit, a second channel switching control unit, and a second relay channel switching matrix. The second relay channel switching matrix is ​​operatively connected to the guided wave receiving sensor array to receive echo signals. The second channel switching control unit is configured to receive a second channel selection control signal from the main control module via the second isolation communication unit, thereby transmitting the echo signal through the channel selected in the second relay channel switching matrix to the signal buffer conditioning unit. The signal acquisition unit is operatively connected to the signal buffer conditioning unit and is used to acquire the echo signal according to the acquisition control signal transmitted from the main control module via the second isolation communication unit.

[0016] The beneficial effects of the crosstalk-free guided wave monitoring hardware system of this application include, but are not limited to: (1) eliminating crosstalk signals from guided wave excitation to guided wave reception, thus eliminating blind spots in guided wave monitoring. (2) communicating with a host computer to complete various parameter configurations and data processing, with a wide range of applications. (3) exciting piezoelectric sensors and achieving rapid gating of any channel from multiple channels. (4) receiving and acquiring piezoelectric sensor signals and achieving rapid gating of any channel from multiple channels. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall system structure of the present invention.

[0018] Figure 2a This is a comparison diagram of the received signals of the present invention.

[0019] Figure 2b This is a comparison diagram of the received signals of the present invention.

[0020] Figure 3a This is a comparison diagram of common-mode impedance coupling interference of the present invention.

[0021] Figure 3b This is a comparison diagram of common-mode impedance coupling interference of the present invention.

[0022] Figure 4a This is a diagram illustrating the attenuation pattern of electromagnetic waves in a metallic body according to the present invention.

[0023] Figure 4b This is a diagram illustrating the attenuation pattern of electromagnetic waves in a metallic body according to the present invention.

[0024] Figure 5 This is a schematic diagram of the main control module structure of the present invention.

[0025] Figure 6 This is a schematic diagram of the isolated communication unit structure of the present invention.

[0026] Figure 7This is a schematic diagram of the isolated power supply unit structure of the present invention.

[0027] Figure 8 This is a schematic diagram of the guided wave signal excitation module structure of the present invention.

[0028] Figure 9 This is a schematic diagram of the guided wave signal receiving module structure of the present invention. Detailed Implementation Plan

[0029] The implementation of the technical solution will be described in further detail below with reference to the accompanying drawings.

[0030] In practical engineering applications using guided wave monitoring systems for structural health monitoring, a highly amplitude crosstalk signal exists at the front end of the received signal. This crosstalk signal prevents effective identification of fault signals within the corresponding detection range. Because these guided wave monitoring systems use piezoelectric sensors, also known as piezoelectric elements, which are high-impedance sensors, an excitation signal of several hundred volts must be applied to the excitation sensor to achieve effective guided wave excitation. The inventors discovered that this high-voltage excitation signal is the root cause of crosstalk in the received signal.

[0031] Traditional guided wave monitoring systems use a module that integrates guided wave excitation and echo reception. Because the excitation and reception parts are integrated and share a common ground, this design cannot avoid crosstalk in the received guided wave.

[0032] The inventors discovered that crosstalk signals are generated through two main pathways: First, through coupling interference from the system's common-mode impedance on the ground plane. This occurs when the excitation and receiving channels share a common-mode impedance. The operating current of the excitation channel acts on this common-mode impedance, creating an interference potential. This interference potential is then collected by the receiving channel and superimposed on the received signal to form the crosstalk signal. Second, through coupling interference from spatial electromagnetic fields. When the excitation channel operates, it releases an electromagnetic field signal into space. The receiving channel experiences coupling with this electromagnetic field, generating an interference potential. This interference potential is also collected by the receiving channel and superimposed on the received signal to form the crosstalk signal.

[0033] Further research by the inventors revealed the following regarding the impact of crosstalk signals on structural health monitoring: Figure 2aAs shown, traditional guided wave monitoring systems acquire a crosstalk signal with extremely large amplitude at the receiving end. This signal is also subject to saturation distortion due to limitations in system power supply voltage and signal amplifier gain. Because the crosstalk signal has a very large amplitude, while typical fault signals have smaller amplitudes, the fault signal is often submerged in the crosstalk, making it impossible to effectively identify fault signals within the detection distance range corresponding to the crosstalk signal's time-domain waveform—thus creating a monitoring blind zone. Taking common guided wave operating parameters as an example—a guided wave frequency of 100kHz, 5 periods, and a material wave velocity of 5000m / s—the calculated interference coverage monitoring distance d is 0.25m. This interference area significantly impacts the system's monitoring and analysis results.

[0034]

[0035] When the received signal acquired by the waveguide system has no crosstalk signal, such as Figure 2b As shown, fault signals with smaller amplitudes can be effectively identified by relevant monitoring algorithms. In this case, the system has no monitoring blind spots and can be applied to the working conditions of health monitoring in hotspot areas.

[0036] Regarding the coupling interference between the electromagnetic field of the excitation channel and the receiving channel: Because the excitation channel in the system has a current loop and an operating current exists when the guided wave is excited, and the excitation waveform of the guided wave is an AC signal, the excitation loop can emit a changing magnetic field into space. This changing magnetic field generates an electric field, and the changing electric field generates a magnetic field. These two fields constitute an inseparable unified field—the electromagnetic field—and the propagation of this changing electromagnetic field in space forms electromagnetic waves.

[0037] Therefore, in order to achieve effective health monitoring of structural hotspot areas, a crosstalk-free guided wave excitation receiving hardware system is needed to eliminate the fault identification blind zone caused by crosstalk signals, thereby expanding the applicable working conditions of guided wave damage monitoring technology.

[0038] The inventors discovered coupling interference related to the common-mode impedance of the system ground plane. For example... Figure 3a The diagram shown is an equivalent analysis diagram for a system excitation receiving a shared ground plane. The ground plane is an equipotential body that serves as the potential reference point for a circuit or system. It is a common conductor for all circuits within the circuit or system, and current in any circuit or system needs to pass through the ground plane to form a loop. However, every conductor has a certain impedance. When current flows through the ground plane, according to Ohm's law, a potential will exist on the ground plane, indicating that the ground plane is not an ideal equipotential body. Figure 3a The guided wave excitation source is simplified to an ideal voltage source Vs, and the guided wave excitation sensor is simplified to a load Z. L The guided wave receiver sensor is simplified to an ideal voltage source V. R and internal resistance Z RThe waveguide receiver is simplified to an ideal voltmeter Vin, where the waveguide excitation channel current is Is and the waveguide receiving channel current is I. R By setting the common-mode impedance of the ground plane for both the excitation and receiving channels to Z0, the effect of the excitation channel on the receiving channel due to the common-mode impedance can be calculated as follows:

[0039]

[0040]

[0041] The above calculations show that when the value of Z0 is 0, the interference signal can be eliminated, and the acquired signal is equal to the signal emitted by the sensor. For example... Figure 3b As shown, the inventors discovered that by isolating the ground plane in the system, the common-mode impedance of the ground plane in the excitation channel and the receiving channel can be removed, thereby eliminating interference signals. The implementation of ground plane isolation first involves separating the excitation module and the receiving module.

[0042] Therefore, the structural principle diagram of a crosstalk-free guided wave monitoring system according to an embodiment of this application is as follows: Figure 1 As shown, it includes a main control module 10, a power supply module 20, an isolation module 30, a guided wave signal excitation module 40, and a guided wave signal receiving module 50. The main control module 10 of this crosstalk-free guided wave monitoring system can receive configuration parameters from the host computer, control the guided wave signal excitation unit to emit guided wave signals, and simultaneously control the guided wave signal receiving unit to start sensor echo signal acquisition and buffer the guided wave signals. After signal acquisition is completed, the buffered guided wave signals are uploaded to the host computer for subsequent processing. Figure 5 As shown, the main control module 10 can adopt a dual-core architecture of ARM processor 101 and FPGA processor 102. The ARM processor 101 leverages its flexible application advantages as the main processor, responsible for controlling the switching of communication unit 103 and waveguide excitation receiving channel, while the FPGA processor 102 leverages its high-speed parallel advantages as the slave processor, responsible for synchronously controlling the generation of waveguide signals and the acquisition of echo signals.

[0043] The isolation module of the crosstalk-free guided wave monitoring system includes a first isolation module 30A coupled between the main control module 10, the guided wave signal excitation module 40, and the power supply module 20, and a second isolation module 30B coupled between the main control module 10, the guided wave signal receiving module 50, and the power supply module 20. The first isolation module 30A and the second isolation module 30B can have the same structure. The first isolation module 30A consists of a first isolation communication unit 301A and a first isolation power supply unit 302A; the second isolation module 30B consists of a second isolation communication unit 301B and a second isolation power supply unit 302B, and is an important component for realizing the system's ground plane segmentation. The principles of the first isolation communication unit 301A and the second isolation communication unit 302B are as follows: Figure 6 As shown, isolation chip 3011 is used to isolate the input ground GNDI and the output ground GNDO. The logic control signal INx is converted into a high-frequency AC signal through input buffer 3012. The high-frequency AC signal is coupled to the output terminal through isolation capacitor 3013. Output buffer 3014 restores the high-frequency AC signal to the logic control signal OUTx, thereby realizing the cross-ground plane isolated transmission of the logic control signal.

[0044] The isolation chip may be, for example, an ISO776x six-channel digital isolator.

[0045] The internal ground plane of the crosstalk-free guided wave monitoring system is divided into three parts: the main control ground GND, the excitation ground SGND, and the receiving ground RGND, which are not directly electrically connected, to eliminate the common-mode impedance between the guided wave excitation channel and the guided wave receiving channel, thereby eliminating the coupling crosstalk caused by this common-mode impedance.

[0046] For example, the main control module is located in the first internal ground plane portion, the waveguide signal excitation module is located in the second internal ground plane portion, and the waveguide signal receiving module is located in the third internal ground plane portion. The first internal ground plane portion, the second internal ground plane portion, and the third internal ground plane portion are not directly electrically connected.

[0047] The first internal ground plane portion where the main control module is located has a main control ground GND, the second internal ground plane portion where the guided wave signal excitation module is located has an excitation ground SGND, and the third internal ground plane portion where the guided wave signal receiving module is located has a receiving ground RGND. The main control ground GND, excitation ground SGND, and receiving ground RGND are isolated from each other and have no direct electrical connection.

[0048] In some embodiments, a shielding cover is installed outside the waveguide signal receiving module, which, together with the receiving ground RGND of the printed circuit board's internal electrical layer, forms a complete shielding space to isolate the radiation effect of the spatial electromagnetic field of the waveguide signal transmitting module, thereby eliminating the coupling crosstalk caused by this radiation effect.

[0049] The guided wave signal excitation module is used for the generation, conditioning, power amplification, and channel switching of guided wave signals, enabling rapid gating and excitation of any channel in the guided wave excitation sensor array. The guided wave signal excitation module 40 is configured as follows: Figure 8 As shown. The guided wave signal excitation module has an internal power supply unit 401, which is responsible for various voltage transformations required by the guided wave signal excitation module. The guided wave signal excitation module receives control signals from the ARM processor 101 and operates the first relay channel switching matrix 405 through the first channel switching control unit 402 to complete the selection and switching of any guided wave excitation channel. The guided wave signal excitation module receives control signals from the FPGA processor 102 and operates the guided wave signal generation unit 403 to generate the original guided wave signal. After passing through the power amplification unit 404 to obtain a high-voltage single-channel guided wave signal, it is input into the first relay channel switching matrix 405. The first relay channel switching matrix 405 consists of n first single-pole relays connected at one end, and the other ends of the n first single-pole relays are respectively connected to n piezoelectric sensors in the guided wave excitation sensor array 406, where n is the number of channels.

[0050] The guided wave signal receiving module is used for receiving, buffering, conditioning, acquiring, and switching channels of guided wave signals. It can quickly select and receive any channel in the guided wave receiving sensor array. (The guided wave signal receiving module 50 is mentioned in the original text.) Figure 9 As shown. The guided wave signal receiving module is entirely enclosed inside the shielding cover 60 to eliminate electromagnetic field coupling interference in the excitation channel. The guided wave signal receiving module has a power supply unit 501 inside, which is responsible for various voltage transformations required by the guided wave signal receiving module. The module receives control signals from the ARM processor 101 and operates the second relay channel switching matrix 503 through the second channel switching control unit 502 to complete the selection and switching of any guided wave receiving channel. The second relay channel switching matrix 503 consists of n second single-pole relays connected at one end, and the other end of the second single-pole relays is connected to n piezoelectric sensors of the guided wave receiving sensor array 504, where n is the number of channels. The single-channel guided wave receiving signal output by the second relay channel switching matrix 503 is processed by the signal buffer conditioning unit 505 and then sent as an input signal to the signal acquisition unit 506. The guided wave signal receiving module receives control signals from the FPGA processor 102 and starts the signal acquisition unit 506 to convert the guided wave receiving signal and upload it to the FPGA processor 102.

[0051] Regarding the coupling interference of the electromagnetic field from the excitation channel to the receiving channel, the inventors discovered that electromagnetic field shielding can be achieved by using a shielding cover made of a good conductor of metal to wrap around the outside of the relevant circuit, which greatly attenuates the coupling interference effect of the electromagnetic field.

[0052] Therefore, in some embodiments of this application, a shielding cover 60 is installed outside the guided wave signal receiving module 50 to isolate the radiated electromagnetic field of the guided wave signal excitation module 40 and the coupling crosstalk caused therefrom.

[0053] When electromagnetic waves incident on a good metallic conductor, absorption and reflection occur. During absorption and reflection, the electromagnetic energy is greatly attenuated, thus providing a shielding effect. For example... Figure 4a As shown, the electric and magnetic field strengths of the electromagnetic wave incident on the surface of the metal are E0 and H0, respectively. The distance the electromagnetic wave penetrates into the metal is b, and the electric and magnetic field strengths of the electromagnetic wave inside the metal are E0 and H0, respectively. b and H b The skin depth of metallic materials is δ, therefore

[0054]

[0055]

[0056] Regarding the skin depth δ of metallic materials, such as Figure 4b The figure shows the incident distance at which the intensity of the electromagnetic wave incident on the metal body attenuates to 1 / e of its original intensity, i.e., 0.37 times. It reflects the metal body's absorption capacity for electromagnetic waves; the smaller the skin depth δ, the stronger the absorption capacity. Its expression is as follows, where f is the electromagnetic wave rate, μ is the permeability of the metal body, and μ0 is the permeability of free space (4π × 10⁻⁶). -7 H / m), μ r Let σ be the relative permeability of the metal, σ be the electrical conductivity of the metal, and σ0 be the electrical conductivity of copper (5.82 × 10⁻⁶). 7 s / m), σ r represents the electrical conductivity of the metal relative to copper.

[0057]

[0058]

[0059]

[0060] As can be seen from the above formula, the shielding effect of a metal shield on electromagnetic fields in space mainly depends on the type of metal material, the thickness of the shielding layer, and the frequency of the electromagnetic field.

[0061] To address this characteristic, the crosstalk-free guided wave monitoring system proposed in this application uses a 0.2mm copper plate as a shielding material to cover the entire circuitry of the guided wave signal receiving module. Its effect is to achieve an attenuation factor of not less than 160dB, or 10 dB, within the electromagnetic field frequency range of 10Hz to 30GHz. 8 It can cover the commonly used frequency range of 1kHz~10MHz for guided wave excitation of the system, ensuring the excellent shielding effect of the receiving channel on the electromagnetic field of the excitation channel.

[0062] The system's power supply module 20 can provide various power conversions required for system operation. The power supply module can be, for example, a 220V AC power supply module or a DC power supply module.

[0063] The first isolation power supply 302A and the second isolation power supply 302B can provide power to circuits on different ground planes when the main control ground GND, excitation ground SGND and receiving ground RGND are isolated from each other and have no direct electrical connection.

[0064] The principles of the first isolation power supply unit 302A and the second isolation power supply 302B are as follows: Figure 7 As shown, the PWM controller 3020 controls the power switch 3021 to generate AC current at the power input terminal. This current is coupled to the output terminal through the transformer 3022 and converted into DC power by the rectifier and filter circuit 3023. At the same time, the output voltage of the rectifier and filter circuit 3023 is sampled and compared with the reference voltage by the sampling and comparison circuit 3024. The difference is transmitted to the PWM controller 3020 through the isolation feedback circuit 3025 to form a closed-loop control to stabilize the power supply at the output terminal, thereby realizing power transmission across the ground plane.

[0065] The crosstalk-free guided wave monitoring system is configured to operate in the following manner:

[0066] Step 1: Connect the power supply. The crosstalk-free guided wave monitoring system completes the power supply of the entire crosstalk-free guided wave monitoring system through the coordinated action of the power supply module 20, the isolation power supply unit 301 and the power supply units inside each module.

[0067] Step 2: The crosstalk-free guided wave monitoring system 100 communicates with the host computer and configures various operating parameters;

[0068] Step 3: After the ARM processor 101 controls the switching of the system excitation channel and the receiving channel according to the operating parameters, it synchronizes the operating parameters to the FPGA processor 102.

[0069] Step 4: The FPGA processor 102 controls the signal generation and signal acquisition unit 506 to work synchronously according to the operating parameters to start the guided wave excitation receiving process;

[0070] Step 5: The FPGA processor 102 synchronizes the acquired guided wave receiver data to the ARM processor 101;

[0071] Step 6: The ARM processor 101 uploads the waveguide reception data to the host computer 200 through the communication unit 70;

[0072] Step 7: For multiple guided wave signal excitation and acquisition processes, simply repeat the relevant operations from Step 2 to Step 6.

[0073] This invention provides an integrated active / passive highly directional circular distributed sensor. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0074] The specific structural and functional details disclosed herein are merely representative and are intended to describe exemplary embodiments of this application. However, this application may be implemented in many alternative forms and should not be construed as being limited solely to the embodiments set forth herein.

[0075] It should be understood that although the terms "first," "second," etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are used merely to distinguish one unit from another. For example, without departing from the scope of the exemplary embodiments, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0076] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms “a” and “an” as used herein are also intended to include the plural. It should also be understood that the terms “comprising” and / or “including” as used herein specify the presence of the stated features, integers, steps, operations, units, and / or components, without excluding the presence or addition of one or more other features, integers, steps, operations, units, components, and / or combinations thereof.

[0077] It should also be mentioned that in some alternative implementations, the functions / actions mentioned may occur in a different order than those shown in the figures. For example, depending on the functions / actions involved, the two figures shown successively may actually be executed substantially simultaneously or sometimes in reverse order.

[0078] The prior description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0079] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A crosstalk-free guided wave monitoring system, characterized in that: include The guided wave signal excitation module is configured to generate an excitation guided wave signal; A guided wave excitation sensor array, operably connected to the guided wave signal excitation module, is configured to receive the excitation guided wave signal and generate an excitation signal based on the excitation guided wave signal; A waveguide receiving sensor array is configured to receive the echo signal of the excitation signal; A guided wave signal receiving module, operably connected to the guided wave receiving sensor array, is configured to synchronously acquire the echo signal; wherein, the guided wave signal excitation module is operably connected to the main control module via a first isolation communication unit and is controlled by the main control module to generate the excitation guided wave signal; the guided wave signal receiving module is operably connected to the main control module via a second isolation communication unit and is controlled by the main control module to synchronously acquire the echo signal; The crosstalk-free guided wave monitoring system also includes a power supply module; the guided wave signal excitation module includes a first power supply unit, which is connected to the power supply module through a first isolation power supply unit; the guided wave signal receiving module includes a second power supply unit, which is connected to the power supply module through a second isolation power supply unit. The first isolated communication unit includes a first input buffer, a first isolation capacitor, and a first output buffer. The first input buffer is configured to convert a logic control signal into a high-frequency AC signal. The first isolation capacitor is configured to couple the high-frequency AC signal to the output terminal of the first isolated communication unit. The first output buffer is configured to restore the high-frequency AC signal to a logic control signal, thereby achieving cross-ground plane isolated transmission of the logic control signal. The input ground GNDI of the first input buffer is isolated from the output ground GNDO of the first output buffer; and / or The second isolated communication unit includes a second input buffer, a second isolation capacitor, and a second output buffer. The second input buffer is configured to convert a logic control signal into a high-frequency AC signal. The second isolation capacitor is configured to couple the high-frequency AC signal to the output terminal of the second isolated communication unit. The second output buffer is configured to restore the high-frequency AC signal to a logic control signal, thereby realizing cross-ground plane isolated transmission of the logic control signal. The input ground GNDI of the second input buffer is isolated from the output ground GNDO of the second output buffer.

2. The crosstalk-free guided wave monitoring system according to claim 1, characterized in that: The crosstalk-free guided wave monitoring system has a unified internal ground plane. The main control module is located in the first internal ground plane part, the guided wave signal excitation module is located in the second internal ground plane part, and the guided wave signal receiving module is located in the third internal ground plane part. The first internal ground plane part, the second internal ground plane part, and the third internal ground plane part are not directly electrically connected.

3. The crosstalk-free guided wave monitoring system according to claim 2, characterized in that: The first internal ground plane portion where the main control module is located has a main control ground GND, the second internal ground plane portion where the guided wave signal excitation module is located has an excitation ground SGND, and the third internal ground plane portion where the guided wave signal receiving module is located has a receiving ground RGND. The main control ground GND, the excitation ground SGND, and the receiving ground RGND are isolated from each other.

4. The crosstalk-free guided wave monitoring system according to claim 2, characterized in that: A shielding cover is installed outside the guided wave signal receiving module, which, together with the receiving ground RGND of the printed circuit board, forms a complete shielding space to isolate the radiation of the spatial electromagnetic field of the guided wave signal transmitting module.

5. The crosstalk-free guided wave monitoring system according to claim 1, characterized in that: The power supply module is either an AC power supply module or a DC power supply module.

6. The crosstalk-free guided wave monitoring system according to claim 1, characterized in that: The first isolated power supply unit includes a first PWM controller, a first power switch, a first transformer, a first rectifier and filter circuit, a first sampling and comparison circuit, and a first isolation feedback circuit. The first PWM controller is configured to control the first power switch to generate a first AC current at the power input terminal of the first isolated power supply unit. The first transformer is configured to couple the first AC current to the output terminal of the first isolated power supply unit and convert it into a first DC power supply through the first rectifier and filter circuit. The output terminal of the first rectifier and filter circuit is sampled by the first sampling and comparison circuit, and the output voltage of the first DC power supply is compared with a first reference voltage to obtain a first difference. The first isolation feedback circuit is configured to transmit the first difference to the first PWM controller to form a closed-loop control to stabilize the power supply at the output terminal of the first isolated power supply unit. and / or The second isolated power supply unit includes a second PWM controller, a second power switch, a second transformer, a second rectifier and filter circuit, a second sampling and comparison circuit, and a second isolated feedback circuit. The second PWM controller is configured to control the second power switch to generate a second AC current at the power input terminal. The second transformer is configured to couple the second AC current to the output terminal and convert it into a second DC power supply through the second rectifier and filter circuit. The output terminal of the second rectifier and filter circuit is sampled by the second sampling and comparison circuit, and the output voltage of the second DC power supply is compared with a second reference voltage to obtain a second difference. The second isolated feedback circuit is configured to transmit the second difference to the second PWM controller to form a closed-loop control to stabilize the power supply at the output terminal of the second isolated power supply unit.

7. The crosstalk-free guided wave monitoring system according to claim 1, characterized in that: The guided wave signal excitation module includes a guided wave signal generation unit, a power amplification unit, a first channel switching control unit, and a first relay channel switching matrix. The guided wave signal generation unit receives a control signal from the main control module via the first isolation communication unit to generate the excitation guided wave signal. The power amplification unit is configured to amplify the excitation guided wave signal and send it to the first relay channel switching matrix. The first channel switching control unit is configured to receive a first channel selection control signal from the main control module via the first isolation communication unit to transmit the excitation guided wave signal through the selected channel in the first relay channel switching matrix to the guided wave excitation sensor array operably connected to it.

8. The crosstalk-free guided wave monitoring system according to claim 1, characterized in that: The guided wave signal receiving module includes a signal buffer conditioning unit, a signal acquisition unit, a second channel switching control unit, and a second relay channel switching matrix. The second relay channel switching matrix is ​​operably connected to the guided wave receiving sensor array to receive echo signals. The second channel switching control unit is configured to receive a second channel selection control signal from the main control module via the second isolation communication unit, thereby transmitting the echo signal to the signal buffer conditioning unit through the channel selected in the second relay channel switching matrix. The signal acquisition unit is operably connected to the signal buffer conditioning unit and is used to acquire the echo signal according to the acquisition control signal from the main control module transmitted via the second isolation communication unit.

Images