Electromagnetic ultrasonic one-way wave excitation system and method

Abstract

The invention discloses an electromagnetic ultrasonic one-way wave excitation system and method. The electromagnetic ultrasonic one-way wave excitation system comprises a signal generation device, a multi-path power amplifier circuit and an electromagnetic ultrasonic transducer, the multi-channel power amplifier circuit is electrically connected to the output end of the signal generating device, the multi-channel power amplifier circuit comprises at least two power amplifier channels which are connected in parallel, and each power amplifier channel comprises a phase and delay control circuit, a driving circuit and a power amplifier circuit which are connected in sequence; the electromagnetic ultrasonic transducer is electrically connected to the output end of the multi-path power amplifier circuit and comprises a plurality of groups of excitation coils and permanent magnets, the number of the excitation coils is the same as that of the power amplifier channels, and the permanent magnets are arranged above the excitation coils; the input end of each group of exciting coils is electrically connected with the output end of the power amplification circuit of the corresponding power amplification channel; the number of the permanent magnets is one more than the group number of the excitation coils, and the interface of the adjacent permanent magnets directly faces the center of one group of excitation coils. The amplitude of an electromagnetic ultrasonic excitation signal can be improved, and meanwhile, the detection blind area of the signal is reduced.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic ultrasound and relates to an electromagnetic ultrasound unidirectional wave excitation system and method. Background Technology

[0002] With the increasing size and complexity of engineering equipment structures, and the widespread application of high-strength metallic materials, these materials are increasingly designed to withstand high power, high speed, and high temperature, placing higher demands on the safe and reliable operation of equipment. During long-term service, due to the complex and variable actual operating conditions, external loads and internal stresses combine, especially when tensile stress reaches the material's yield strength. This leads to a significant decrease in structural stiffness and fatigue strength, resulting in fatigue, deformation, microcracks, and ultimately structural fracture and failure. Researching defect detection methods and fatigue life evolution laws in sheet metal will provide crucial assessment data for the service status and life prediction of materials. Therefore, conducting research on defect and fatigue characterization methods for sheet metal, and performing quantitative defect detection and residual fatigue life assessment for key components of major metal equipment, has become a major topic and primary development direction in the fields of nondestructive testing and structural health monitoring both domestically and internationally.

[0003] Electromagnetic ultrasound (EMU) boasts advantages such as low coupling, high precision, low requirements on the surface of the test specimen, and high adjustability of excitation parameters, making it a promising technology for metal coating quality inspection. However, while EMU offers significant advantages, its drawbacks are also considerable. The most significant is its relatively low transduction efficiency, which leads to a series of detection problems, such as unclear defect characteristics, low quantitative detection accuracy, and significant susceptibility to noise signals. Furthermore, a major issue with current technology is that when the number of excitation coil turns is large, the amplitude of the generated electromagnetic ultrasonic packet cannot be further increased, and the packet width is large, resulting in energy dispersion and a large detection blind zone. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an electromagnetic ultrasonic unidirectional wave excitation system and method that can improve the amplitude of the electromagnetic ultrasonic excitation signal and reduce the detection blind zone of the signal.

[0005] To achieve the above objectives, the present invention employs the following technical solution: An electromagnetic ultrasonic unidirectional wave excitation system includes a signal generator, a multi-channel power amplifier circuit, and an electromagnetic ultrasonic transducer. The multi-channel power amplifier circuit is electrically connected to the output terminal of the signal generator. The multi-channel power amplifier circuit includes at least two power amplifier channels connected in parallel. Each power amplifier channel includes a phase and delay control circuit, a drive circuit, and a power amplifier circuit connected in sequence. The electromagnetic ultrasonic transducer is electrically connected to the output of the multi-channel power amplifier circuit. The electromagnetic ultrasonic transducer includes excitation coils divided into several groups, which are the same as the number of power amplifier channels, and permanent magnets disposed above the excitation coils. The input terminal of each set of excitation coils is electrically connected to the output terminal of the power amplifier circuit of the corresponding power amplifier channel; The number of permanent magnets is one more than the number of sets of excitation coils, and the interface between adjacent permanent magnets is directly opposite the center of a set of excitation coils.

[0006] Preferably, the signal generating device includes a main control chip, and the output terminal of the main control chip is electrically connected to the input terminal of the phase and delay control circuit of each power amplifier channel of the multi-channel power amplifier circuit.

[0007] Preferably, the phase and delay control circuit uses the AD9959 chip.

[0008] Preferably, the driving circuit includes two IR2110 chips, and the input terminals of the two IR2110 chips are respectively connected to one output of the phase and delay control circuit in the forward and reverse directions.

[0009] Preferably, the power amplifier circuit is a full-bridge inverter circuit, which consists of an H-bridge structure composed of four MOSFETs, each of which is equipped with an RCD protection circuit and a gate auxiliary circuit.

[0010] Preferably, an impedance matching circuit is provided between the output terminal of the multi-channel power amplifier circuit and the input terminal of the electromagnetic ultrasonic transducer. The impedance matching circuit is a network composed of capacitors and resistors.

[0011] Preferably, the permanent magnet is a PPM permanent magnet, and the width of the PPM permanent magnet is consistent with the width of the excitation coil.

[0012] Preferably, the excitation coils are divided into four groups, and the number of permanent magnets is five.

[0013] Preferably, it includes the following steps: The signal generator produces an initial excitation signal; The multi-channel power amplifier circuit receives the initial excitation signal and converts it into multiple high-power excitation signals with different phases and delays. Multiple high-power excitation signals are applied to the excitation coils of the electromagnetic ultrasonic transducer, which are divided into several groups. Under the bias magnetic field provided by the permanent magnet, ultrasonic waves are excited in the test piece.

[0014] Preferably, the phase difference between the high-power excitation signals applied to the two adjacent sets of excitation coils is 180°; the excitation delay of the high-power excitation signals applied to the two adjacent sets of excitation coils is determined according to the width of the excitation coil, the period of the initial excitation signal, and the wavelength of the ultrasonic wave in the test piece.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The electromagnetic ultrasonic excitation system of this invention includes a multi-channel power amplifier circuit capable of independently adjusting the phase and delay of the excitation signal. Combined with the designed electromagnetic ultrasonic transducer, it can increase the amplitude of the electromagnetic ultrasonic excitation signal while reducing the signal detection blind zone. The function achieved by this invention is not simply replicating a traditional electromagnetic ultrasonic excitation system, but rather by setting different phases and delays for different channels. The output signals of the multi-channel power amplifier circuit are combined and then loaded as a new excitation signal into the electromagnetic ultrasonic transducer. Furthermore, this invention can also achieve the functions of a traditional electromagnetic ultrasonic excitation system; when the phase and delay of different channels are set to the same value, each channel functions as a traditional electromagnetic ultrasonic excitation system.

[0016] Furthermore, the power amplifier circuit employs a full-bridge inverter circuit. Compared to single-transistor and half-bridge inverter circuits, the full-bridge inverter offers higher output power, lower switching losses, and accepts more control methods. Simultaneously, protection circuits and gate auxiliary circuits are provided for each MOSFET to prevent burnout due to overload, short circuits, or other reasons, and to ensure that the MOSFETs are strictly turned on and off according to the pre-defined procedures during operation.

[0017] Furthermore, the excitation coil is divided into several groups, each receiving one excitation signal from the electromagnetic ultrasonic excitation system. After setting appropriate phase and delay for each group of signals, the excitation signals of each group can be completely superimposed, greatly improving the overall excitation signal amplitude. The configuration of the excitation coil and permanent magnet of the electromagnetic ultrasonic transducer can provide a large bias magnetic field for the excitation coil, ensuring the excitation efficiency of the system. Attached Figure Description

[0018] Figure 1 This is a schematic block diagram of the circuit principle of an embodiment of this patent; Figure 2 This is a schematic diagram of the main control circuit in an embodiment of this patent; Figure 3 This is a schematic diagram of the phase and delay control circuit of an embodiment of this patent; Figure 4 This is a schematic diagram of the driving circuit according to an embodiment of this patent; Figure 5 This is a schematic diagram of the power amplifier circuit according to an embodiment of this patent; Figure 6 This is a schematic diagram of the impedance matching circuit in an embodiment of this patent; Figure 7 This is a schematic diagram of the electromagnetic ultrasonic transducer according to an embodiment of this patent; Figure 8This is a comparison of the amplitude of the electromagnetic ultrasonic enhancement wave excited by the embodiment of this patent with that of the electromagnetic ultrasonic wave excited by a conventional electromagnetic ultrasonic excitation system. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0020] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0021] like Figure 1 As shown, the electromagnetic ultrasonic unidirectional wave excitation system of the present invention includes a signal generating device, a multi-channel power amplifier circuit (including a phase and delay control circuit, a drive circuit, and a power amplifier circuit), an impedance matching circuit, and a matching electromagnetic ultrasonic transducer.

[0022] The signal generator is used to generate excitation signals with adjustable frequency and amplitude. The main control chip of the signal generator is an STM32F103 series chip, which features a 72 MHz CPU speed and up to 1 MB of flash memory. It includes a peripheral device control module and full-speed CAN and USB interfaces. The STM32 series ARM Cortex-M3 32-bit flash microcontroller operates with low power and low voltage, combined with excellent real-time performance. The STM32F103 chip has four I / O interfaces (P0-P3), which can meet the control requirements of the multi-channel power amplifier circuit in this invention. Furthermore, by programming the STM32F103 chip, the phase and delay control circuit (implemented via AD9959) can be controlled, allowing for convenient modification of the initial phase and excitation delay of any signal.

[0023] The STM32F103ZET6 is a high-specification chip in the STM32F103 series, featuring a high-performance ARM Cortex-M3 32-bit RISC core running at 72MHz, high-speed embedded memory (up to 512KB flash memory and up to 64KB SRAM), and various enhanced I / O and peripheral devices connected to two APB buses. It provides three 12-bit ADCs, four general-purpose 16-bit timers, and two PWM timers, as well as standard and advanced communication interfaces: up to two I2C, three SPI, two I2Ss, one SDIO, five USARTs, one USB, and one CAN. It operates over a temperature range of –40 to +105°C and a supply voltage of 2.0 to 3.6V.

[0024] The multi-channel power discharge circuit consists of a phase and delay control circuit, a drive circuit, and a power amplifier circuit. For example... Figure 3 As shown, the multi-channel power amplifier circuit uses four channels.

[0025] The phase control and delay control circuit is implemented by AD9959, which can convert the excitation signal generated by the signal generator into multiple signals with different phases and delays as inputs to the drive circuit. The drive circuit consists of IR2110 and its peripheral circuits, which is used to split the input signal into two complementary square wave signals with dead time to drive the four MOS transistors of the power amplifier circuit. The power amplifier circuit adopts a full-bridge inverter circuit, which is used to amplify the excitation signal generated by AD9959 into a high-power excitation signal and load it into the subsequent electromagnetic ultrasonic transducer.

[0026] The connection method between STM32F103 and AD9959 in the signal generator is as follows: Figure 2 , Figure 3As shown: STM32's PA6 is connected to AD9959's CS for chip select; STM32's PB1 is connected to AD9959's SCLK for serial data clock for I / O operations; STM32's PB0 is connected to AD9959's I / O_UPDATE for transferring data from the serial I / O port buffer to the active register on the rising edge; STM32's PA7, PA2, PB10, and PC0 are connected to AD9959's P0-P3 respectively for data pins used for modulation (FSK, PSK, ASK); STM32's PA5 is connected to AD9959's SDIO_0. Used as data pins, dedicated only to serial port I / O; STM32's PA4, PA3, and PA8 are connected to AD9959's SDIO_1-SDIO_3, used as data pins for serial I / O ports or to enable DAC output amplitude ramp-up / ramp-down (RU / RD); STM32's PA9 is connected to AD9959's PWR_DWN_CTL, used for external power-down control; STM32's PA10 is connected to AD9959's MASTER_RESET, used as a reset pin, active high; STM32's GND is connected to AD9959's GND, used as common ground.

[0027] The design of the drive circuit is as follows Figure 4 As shown, the drive circuit consists of two IR2110 chips. One IR2110's HIN and LIN pins are connected to OUT1 and OUT2 of one output of the AD9959, while the other is connected in reverse to OUT2 and OUT1 of the same output. D4, R9, EC6 and D3, R10, EC7 provide bootstrap voltages to the VS pins of the two IR2110 chips, respectively. C6 and EC4, C7 and EC5, and C8 and EC8 provide voltage regulation protection for their respective power supplies. Using a single chip allows for the control of the conduction of both upper and lower MOSFETs, reducing the complexity of the drive circuit and lowering the overall cost of the excitation system.

[0028] Design of power amplifier circuits, such as Figure 5 As shown. The circuit adopts a full-bridge inverter structure design. Each vertical arm of the H-bridge has a MOSFET. The output of the power amplifier circuit is located on the only horizontal arm of the H-bridge. D1, R1, D2, and R2 together form the gate auxiliary circuit of MOSFET1. C1, D3, and R3 together form the RCD protection circuit of MOSFET1. The circuit design of the other three arms is consistent with MOSFET1. J1 is connected to HO1 and VS1, J4 is connected to VS1 and LO1, J2 is connected to HO2 and VS2, and J3 is connected to VS2 and LO2.

[0029] The power amplifier circuit uses a full-bridge inverter circuit. Compared with single-transistor and half-bridge inverter circuits, the full-bridge inverter has higher output power, lower switching losses, and can accept more control methods. At the same time, protection circuits and gate auxiliary circuits are set for each MOSFET to prevent the MOSFET from burning out due to overload, short circuit, etc., and to strictly follow the set turn-on and turn-off methods during the operation of the MOSFET.

[0030] Impedance matching circuit design, such as Figure 6 As shown in the figure. Since the impedance characteristic of the excitation coil of the electromagnetic ultrasonic transducer is inductive, the impedance matching circuit is designed as a network of capacitors and resistors. By adjusting the switches in the network, the values ​​of the capacitors and resistors connected to the network can be adjusted to counteract the inductance of the excitation coil and maximize the excitation power.

[0031] A top view of the electromagnetic ultrasonic transducer design is shown below. Figure 7 As shown, the excitation coils of the electromagnetic ultrasonic transducer are divided into several groups, each receiving one excitation signal from the electromagnetic ultrasonic excitation system. The electromagnetic ultrasonic transducer uses PPM permanent magnets to provide a bias magnetic field. The width of the PPM permanent magnets is consistent with that of the excitation coils, and the number of PPM permanent magnets is one more than the number of groups of excitation coils. This ensures that the interface of adjacent magnets is directly opposite the center of a group of excitation coils. This configuration of excitation coils and permanent magnets can guarantee the maximum excitation efficiency.

[0032] like Figure 7 As shown, the excitation frequency setting of the electromagnetic ultrasonic transducer f The value is 500k, and the period T is 2*10. -6 s, the test piece is an aluminum plate, and the wavelength of the ultrasonic wave in the aluminum plate can be calculated. λ The width is 2.98 mm. The excitation coil is divided into four groups, each group having a width of 4 mm. λ Each group receives one excitation signal from the electromagnetic ultrasonic excitation system; the electromagnetic ultrasonic transducer uses PPM permanent magnets to provide a bias magnetic field, the width of the PPM permanent magnets is consistent with that of the excitation coils, and the number is five (one more than the number of groups of excitation coils).

[0033] After grouping the excitation coils and using the permanent magnets mentioned above, the excitation current within the coils is determined, specifically: the excitation delay between adjacent coils is D*T / λ Where D is the width of the coil (D is...) λ (where T is an integer multiple of 2), and T is the period of the excitation signal. λThe wavelength of the excited ultrasonic wave in the corresponding specimen is determined by the propagation direction of the reinforcement wave (the wave formed by the superposition of ultrasonic waves generated by different coils). The coil that is later in the propagation direction is excited later. Since the magnetic fields of adjacent permanent magnets are opposite, the excitation current needs to be further adjusted. The opposite magnetic field will cause the generated ultrasonic waves to have a phase difference of 180°. Therefore, phase compensation needs to be performed in the excitation current, that is, the phase difference of the excitation current between adjacent coils is 180°.

[0034] The excitation coil of the electromagnetic ultrasonic transducer is divided into several groups, each receiving one excitation signal from the electromagnetic ultrasonic excitation system. After setting appropriate phase and delay for each group of signals, the excitation signals of each group can be completely superimposed, greatly improving the overall excitation signal amplitude. The configuration of the excitation coil and permanent magnet of the electromagnetic ultrasonic transducer can provide a large bias magnetic field for the excitation coil, ensuring the excitation efficiency of the system.

[0035] The excited electromagnetic ultrasound reinforcement wave propagates to the right, therefore the coil on the left is excited first, followed by the coil on the right. The excitation signal is a Tuneburst sine wave modulated by a sine wave with a period of 5T, and the phase difference of the excitation current between adjacent coils is 180°. In summary, the excitation current of the four sets of excitation coils (from left to right) is expressed in Table 1, where the phase adjustment of the modulation signal is to achieve its maximum value simultaneously with the excitation signal. A comparison (after normalization) of the amplitude of the excited electromagnetic ultrasound reinforcement wave of this embodiment and the electromagnetic ultrasound excited by a conventional electromagnetic ultrasound excitation system is shown below. Figure 8 As shown.

[0036] Table 1

[0037] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0038] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0039] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0040] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0041] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

[0042] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this patent should not be determined by reference to the above description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

Claims

1. An electromagnetic ultrasonic unidirectional wave excitation system, characterized in that, Includes a signal generator, a multi-channel power amplifier circuit, and an electromagnetic ultrasonic transducer; The multi-channel power amplifier circuit is electrically connected to the output terminal of the signal generator. The multi-channel power amplifier circuit includes at least two power amplifier channels connected in parallel. Each power amplifier channel includes a phase and delay control circuit, a drive circuit, and a power amplifier circuit connected in sequence. The electromagnetic ultrasonic transducer is electrically connected to the output of the multi-channel power amplifier circuit. The electromagnetic ultrasonic transducer includes excitation coils divided into several groups, which are the same as the number of power amplifier channels, and permanent magnets disposed above the excitation coils. The input terminal of each set of excitation coils is electrically connected to the output terminal of the power amplifier circuit of the corresponding power amplifier channel; The number of permanent magnets is one more than the number of sets of excitation coils, and the interface between adjacent permanent magnets is directly opposite the center of a set of excitation coils.

2. The electromagnetic ultrasonic unidirectional wave excitation system according to claim 1, characterized in that, The signal generating device includes a main control chip, the output of which is electrically connected to the input of the phase and delay control circuit of each power amplifier channel of the multi-channel power amplifier circuit.

3. The electromagnetic ultrasonic unidirectional wave excitation system according to claim 1, characterized in that, The phase and delay control circuit uses the AD9959 chip.

4. The electromagnetic ultrasonic unidirectional wave excitation system according to claim 1, characterized in that, The driving circuit includes two IR2110 chips, and the input terminals of the two IR2110 chips are respectively connected to one output of the phase and delay control circuit in the forward and reverse directions.

5. The electromagnetic ultrasonic unidirectional wave excitation system according to claim 1, characterized in that, The power amplifier circuit is a full-bridge inverter circuit, which consists of an H-bridge structure composed of four MOSFETs. Each MOSFET is equipped with an RCD protection circuit and a gate auxiliary circuit.

6. The electromagnetic ultrasonic unidirectional wave excitation system according to claim 1, characterized in that, An impedance matching circuit is provided between the output of the multi-channel power amplifier circuit and the input of the electromagnetic ultrasonic transducer. The impedance matching circuit is a network composed of capacitors and resistors.

7. The electromagnetic ultrasonic unidirectional wave excitation system according to claim 1, characterized in that, The permanent magnet is a PPM permanent magnet, and the width of the PPM permanent magnet is consistent with the width of the excitation coil.

8. The electromagnetic ultrasonic unidirectional wave excitation system according to claim 1, characterized in that, The excitation coils are divided into four groups, and the number of permanent magnets is five.

9. A method for electromagnetic ultrasonic unidirectional wave excitation based on the system according to any one of claims 1-8, characterized in that, Includes the following steps: The signal generator produces an initial excitation signal; The multi-channel power amplifier circuit receives the initial excitation signal and converts it into multiple high-power excitation signals with different phases and delays. Multiple high-power excitation signals are applied to the excitation coils of the electromagnetic ultrasonic transducer, which are divided into several groups. Under the bias magnetic field provided by the permanent magnet, ultrasonic waves are excited in the test piece.

10. The electromagnetic ultrasonic unidirectional wave excitation method according to claim 9, characterized in that, The phase difference between the high-power excitation signals applied to the two adjacent sets of excitation coils is 180°; the excitation delay of the high-power excitation signals applied to the two adjacent sets of excitation coils is determined based on the width of the excitation coil, the period of the initial excitation signal, and the wavelength of the ultrasonic wave in the test piece.

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