CN106442742B

CN106442742B - 100 kW-level broadband electromagnetic ultrasonic excitation source

Info

Publication number: CN106442742B
Application number: CN201610800101.6A
Authority: CN
Inventors: 郑阳; 周进节
Original assignee: China Special Equipment Inspection and Research Institute
Current assignee: China Special Equipment Inspection and Research Institute
Priority date: 2016-08-31
Filing date: 2016-08-31
Publication date: 2023-11-03
Anticipated expiration: 2036-08-31
Also published as: CN106442742A

Abstract

The invention discloses a 100 kW-level broadband electromagnetic ultrasonic excitation source. Wherein, this 100kW level broadband electromagnetic ultrasonic excitation source includes: generating a first set of initial signals and a second set of initial signals by a signal generator; then, amplifying the first group of initial signals through a left arm high-end driving circuit and a right arm low-end driving circuit so as to drive the left arm high-end switch and the right arm low-end switch to be conducted, and outputting high-voltage signals by the frequency selection circuit; amplifying a second group of initial signals by a left arm low-end driving circuit and a right arm high-end driving circuit to drive the left arm low-end switch and the right arm high-end switch to be conducted, wherein at the moment, the voltage output by the frequency selection circuit is approximately zero; the frequency selection circuit outputs high-voltage pulse signals with a limited period by controlling the conduction of the multi-path switch circuit so as to excite the electromagnetic ultrasonic transducer to generate ultrasonic waves in a structure to be detected. The invention solves the technical problem of lower output power of the electromagnetic ultrasonic detection instrument in the prior art in a wider frequency range.

Description

100 kW-level broadband electromagnetic ultrasonic excitation source

Technical Field

The invention relates to the field of nondestructive testing, in particular to a 100 kW-level wide-frequency electromagnetic ultrasonic excitation source.

Background

At present, a plurality of high-temperature pipelines, boilers, reactors and other metal equipment exist in petrochemical industry, electric power industry and other industries. Because part of high-temperature metal equipment is difficult to stop for detection or the cost of stop for detection is too high, development of in-service detection technology of the high-temperature metal equipment is urgently required. At present, the common piezoelectric ultrasonic detection technology makes it difficult to effectively detect equipment with the temperature of more than 300 ℃ on site due to the volatilization of a coupling agent and the limitation of Curie temperature of a piezoelectric material.

The electromagnetic ultrasonic detection technology does not need a coupling agent, and is particularly suitable for nondestructive detection of high-temperature metal equipment due to the non-contact characteristic of the electromagnetic ultrasonic detection technology. However, the temperature rise, on the one hand, can cause the change of the electric conduction and magnetic conduction characteristics of the material to be detected, and sometimes can cause the reduction of the electric-acoustic energy conversion efficiency; on the other hand, a change in the propagation characteristics of the acoustic wave is also caused. Further, since the high temperature equipment is mostly made of various stainless steel materials, for example, P11 stainless steel is commonly used for high temperature materials at 400-500 ℃ and 12Cr1MoVG stainless steel is commonly used for high temperature materials at 500-600 ℃, and the magnetic permeability of the materials is very weak, so that the detection signal is further attenuated or the signal to noise ratio is reduced.

At present, the transient output power of electromagnetic ultrasonic detection instruments widely used at home and abroad is below tens of kilowatts. Because of the limitation of the output power of the existing excitation source, the signal-to-noise ratio of the detection signal of the high-temperature metal equipment is poor at present, and the technical scheme for improving the signal-to-noise ratio of the detection signal by increasing the output power of the detection equipment does not exist in the existing technology. In addition, the detection frequencies suitable for different materials in different temperature ranges are different, and the bandwidth of the output signal of the excitation source in the prior art is narrow.

Disclosure of Invention

The embodiment of the invention provides a 100 kW-level broadband electromagnetic ultrasonic excitation source, which at least solves the technical problem that an electromagnetic ultrasonic detection instrument in the prior art has lower output power in a wider frequency range.

According to an aspect of an embodiment of the present invention, there is provided a 100 kW-level broadband electromagnetic ultrasonic excitation source comprising: the signal generator is used for generating a first group of initial signals and a second group of initial signals, wherein the first group of initial signals and the second group of initial signals are signals with opposite polarities, the first group of initial signals comprise an even number of initial signals, and the second group of initial signals comprise an even number of initial signals; the multipath driving circuit is connected with the signal generator and is used for amplifying the first group of initial signals and the second group of initial signals; the multi-path switching circuit is connected with one path of the driving circuit, and the multi-path switching circuit adjusts the running state according to the amplified first group of initial signals and the amplified second group of initial signals, wherein the running state comprises on or off; and the frequency selecting circuit is connected with the multi-path switch circuit through a first end and a second end of the frequency selecting circuit respectively, and an output end of the frequency selecting circuit is connected with the electromagnetic ultrasonic transducer, wherein the frequency selecting circuit outputs a target signal according to the running state, and the target signal is used for exciting the electromagnetic ultrasonic transducer to generate ultrasonic waves in a structure to be detected.

Further, the multiplexing drive circuit includes: the first group of driving circuits are connected with the signal generator and are used for amplifying even initial signals in the first group of initial signals to obtain a first voltage signal group; and the second group of driving circuits are connected with the signal generator and are used for amplifying even initial signals in the second group of initial signals to obtain a second voltage signal group.

Further, the first group of driving circuits includes a left arm high-end driving circuit and a right arm low-end driving circuit, and the second group of driving circuits includes a left arm low-end driving circuit and a right arm high-end driving circuit.

Further, the multi-way switching circuit includes: the first switch group is connected with the first group driving circuit, and when the voltage value of the first voltage signal group loaded at the first end and the second end of the first switch group meets a first preset voltage, the first switch is connected with the group; and the second switch group is connected with the second group driving circuit, and is conducted when the voltage value of the second voltage signal group loaded at the first end and the second end of the second switch group meets a second preset voltage.

Further, the first switch group includes a left arm high-side switch and a right arm low-side switch, the second switch group includes a left arm low-side switch and a right arm high-side switch, wherein the left arm high-side switch includes at least one first field effect transistor, the right arm low-side switch includes at least one second field effect transistor, the left arm low-side switch includes at least one third field effect transistor, and the right arm high-side switch includes at least one fourth field effect transistor.

Further, the drain electrode of each first field effect tube is connected with a high-voltage power supply circuit, and the source electrode of each first field effect tube is connected with the left end of the frequency selection circuit; the source electrode of each second field effect transistor is grounded, and the drain electrode of each second field effect transistor is connected with the right end of the frequency selection circuit; the source electrode of each third field effect tube is grounded, and the drain electrode of each third field effect tube is connected with the left end of the frequency selection circuit; the drain electrode of each fourth field effect tube is connected with a high-voltage power supply circuit, and the source electrode of each fourth field effect tube is connected with the right end of the frequency selection circuit.

Further, the frequency selecting circuit comprises a first capacitor and a transformer, wherein a first end of the first capacitor is connected with a source electrode of each first field effect tube and a drain electrode of each third field effect tube, a second end of the first capacitor is connected with a first end of a primary side of the transformer, a second end of the primary side of the transformer is connected with a drain electrode of the second field effect tube and a source electrode of the fourth field effect tube, and a secondary side of the transformer is connected with the electromagnetic ultrasonic transducer.

Further, the method further comprises the following steps: the high-voltage power supply circuit is characterized in that a first end of the power supply circuit is connected with the drain electrode of each first field effect transistor and the drain electrode of each fourth field effect transistor respectively, a second end of the high-voltage power supply circuit is grounded, and the high-voltage power supply circuit is used for providing high-voltage signals for the frequency selection circuit.

Further, each driving circuit in the multipath driving circuit includes: the digital-analog isolation circuit is connected with the signal generator and used for isolating the interference of a digital circuit in the signal generator on an analog circuit in the 100 kW-level broadband electromagnetic ultrasonic excitation source; the field effect transistor driving circuit is respectively connected with the digital-analog isolation circuit of one path of switching circuit and is used for outputting voltage signals to the input end of the one path of switching circuit connected with the digital-analog isolation circuit, wherein the voltage signals are used for driving the one path of field effect transistor to be turned on or turned off.

Further, the 100 kW-level broadband electromagnetic ultrasonic excitation source further comprises: the device comprises a plurality of suppression circuits, wherein one suppression circuit is connected with one path of field effect transistor, a first end of the suppression circuit is connected with a drain electrode of the path of field effect transistor, and a second end of the suppression circuit is connected with a source electrode of the path of field effect transistor.

Further, each suppression circuit in the plurality of suppression circuits comprises a second capacitor, a resistor and a diode, wherein the second capacitor is connected in series with the diode and then connected in parallel with the source electrode and the drain electrode of the field effect transistor, and the resistor is connected in parallel with two ends of the diode.

Further, each switch circuit in the multi-path switch circuit comprises N field effect transistors, wherein the grid electrode of each field effect transistor in the N field effect transistors is connected with the output end of the field effect transistor driving circuit, the drain electrode of each field effect transistor is connected, the source electrode of each field effect transistor is connected, and N is a positive integer greater than or equal to 1.

Further, the signal generator comprises a field programmable gate array.

In the embodiment of the invention, the even number of initial signals in the first group of initial signals and the even number of initial signals in the second group of initial signals generated by the signal generator are amplified by the multipath driving circuit, then the amplified even number of initial signals are used for controlling the running state of the bridge type switching circuit formed by the multipath switching circuit, and further, the output target signal of the frequency selection circuit is adjusted through the running state.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. In the drawings:

FIG. 1 is a schematic diagram of a 100kW level broadband electromagnetic ultrasonic excitation source according to an embodiment of the present application;

FIG. 2 is a schematic diagram of an alternative 100kW level wide frequency electromagnetic ultrasonic excitation source according to an embodiment of the application;

FIG. 3 is a schematic diagram of a portion of a switching circuit and frequency selection circuit of another alternative 100kW level wide frequency electromagnetic ultrasonic excitation source in accordance with an embodiment of the present application;

FIG. 4 is a schematic diagram of a left arm high-side drive circuit according to an embodiment of the application;

FIG. 5 is a schematic diagram of a left arm low side drive circuit according to an embodiment of the application;

FIG. 6 is a schematic diagram of a right arm high-side drive circuit according to an embodiment of the application;

FIG. 7 is a schematic diagram of a right arm low side drive circuit according to an embodiment of the application;

FIG. 8 is a schematic diagram of a signal generator according to an embodiment of the application;

FIG. 9 is a waveform schematic diagram of a target signal according to an embodiment of the application; and

Fig. 10 is a waveform schematic diagram of an alternative target signal according to an embodiment of the invention.

Detailed Description

In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

In accordance with an embodiment of the present invention, there is provided an embodiment of a 100 kW-level broadband electromagnetic ultrasonic excitation source, it being noted that the steps illustrated in the flowchart of the figures may be performed in a computer system such as a set of computer executable instructions, and while a logical sequence is illustrated in the flowchart, in some cases the steps illustrated or described may be performed in a different order than that illustrated herein.

FIG. 1 is a schematic diagram of a 100kW class broadband electromagnetic ultrasonic excitation source according to an embodiment of the invention, as shown in FIG. 1, the 100kW class broadband electromagnetic ultrasonic excitation source includes: a signal generator 101, a multiplexing drive circuit 102, a multiplexing switch circuit 103, and a frequency selection circuit 104, wherein:

the signal generator 101 is configured to generate a first set of initial signals and a second set of initial signals, where the first set of initial signals and the second set of initial signals are signals with opposite polarities, the first set of initial signals includes an even number of initial signals, and the second set of initial signals includes an even number of initial signals.

In the embodiment of the present invention, the first set of initial signals and the second set of initial signals are voltage signals, and preferably, the initial signals are finite periodic square wave signals. Therefore, in the invention, the signal generator is adopted to emit the limited periodic square wave signal according to the preset frequency, wherein the frequency and the duty ratio of the emitted limited periodic square wave signal are preset.

As shown in fig. 1, the signal generator generates 4 paths of initial signals through ports 1 to 4, wherein the signals generated by ports 1 and 3 are a first set of initial signals, the signals generated by ports 2 and 4 are a second set of initial signals, the signals generated by ports 1 and 3 have the same polarity and the same period, the signals generated by ports 2 and 4 have the same polarity and the same period, however, the signals generated by ports 1 and 2 have opposite polarities and the same period.

The multiplexing drive circuit 102 is connected to the signal generator and is configured to amplify the first set of initial signals and the second set of initial signals.

In an embodiment of the present invention, the multiplexing driving circuit 102 includes: a first group of driving circuits and a second group of driving circuits, wherein the first group of driving circuits is connected with the signal generator 101 and is used for amplifying an even number of initial signals in a first group of initial signals to obtain a first voltage signal group; the second group of driving circuits is also connected to the signal generator 101, and is configured to amplify an even number of initial signals in the second group of initial signals to obtain a second voltage signal group.

Specifically, as shown in fig. 1, the first set of driving circuits includes a left arm high-side driving circuit 1021 and a right arm low-side driving circuit 1023; the second set of drive circuits includes a left arm low side drive circuit 1022 and a right arm high side drive circuit 1024.

As can be seen from fig. 1, the left arm high-end driving circuit 1021 receives the signal output from the port 1, and the right arm high-end driving circuit 1024 receives the signal output from the port 4, wherein the period of the signal output from the port 1 is the same as that of the signal output from the port 4, and the polarities are opposite; the left arm low-side driving circuit 1022 receives the signal output by the port 2, the left arm low-side driving circuit 1023 receives the signal output by the port 3, the period of the signal output by the port 2 is the same as the period of the signal output by the port 3, but the period of the signal output by the port 1 is the same as the period of the signal output by the port 3, and the polarities are the same.

And the multi-path switching circuit 103 is connected with the driving circuit, wherein the multi-path switching circuit adjusts the running state according to the amplified first group of initial signals and the amplified second group of initial signals, and the running state comprises on or off.

In an embodiment of the present invention, the multi-way switch circuit 103 includes: the first switch group is connected with the first driving circuit group, and when the voltage value of the first voltage signal group loaded at the first end and the second end of the first switch group meets a first preset voltage, the first switch is turned on; the second switch group is connected with the second driving circuit group, wherein when the voltage value of the second voltage signal group loaded at the first end and the second end of the second switch group meets a second preset voltage, the second switch group is conducted.

Specifically, as shown in fig. 1, the first switch group includes a left arm high-side switch 1031 and a right arm low-side switch 1033; the second switch set includes a left arm low side switch 1032 and a right arm high side switch 1034, wherein the left arm high side switch includes at least one first field effect transistor, the right arm low side switch includes at least one second field effect transistor, the left arm low side switch includes at least one third field effect transistor, and the right arm high side switch includes at least one fourth field effect transistor. Specifically, the connection relationship among the first field effect transistor, the second field effect transistor, the third field effect transistor, and the fourth field effect transistor will be described in detail in the following embodiments.

As can be seen in fig. 1, the output terminal 6 of the left arm high side switch 1031 is connected to the first terminal 12 of the frequency selection circuit 104 and the input terminal 15 of the left arm low side switch 1032, the input terminal 17 of the left arm high side switch 1031 is connected to the input terminal 18 of the right arm high side switch 1034 and is connected to the output terminal of the high voltage power circuit, and the output terminal 9 of the right arm high side switch 1034 is connected to the second terminal 13 of the frequency selection circuit 104 and the input terminal 16 of the right arm low side switch 1033, respectively, and the output terminal 8 of the left arm low side switch and the output terminal 11 of the right arm low side switch are grounded. Wherein when the first voltage signal applied across 1031 (i.e., across 5 and 6) is greater than or equal to a first preset voltage, the energy conversion device in 1031 is turned on; when the first voltage signal applied across 1033 (i.e., across 10 and 11) is greater than or equal to a first preset voltage, the energy conversion device in 1033 is turned on; when the second voltage signal applied across 1032 (i.e., 7 and 8) is greater than or equal to the second preset voltage, the energy conversion device in 1032 turns on; when the second voltage signal applied across 1034 (i.e., across 9 and 17) is greater than or equal to the second preset voltage, the energy conversion device in 1034 is turned on.

As can be seen from fig. 1, in the embodiment of the present invention, the left arm high-side switch 1031, the left arm low-side switch 1032, the right arm low-side switch 1033 and the right arm high-side switch 1034 form a full-bridge driving circuit, and when 1031, 1032, 1033 and 1034 are alternately turned on, the frequency selection circuit is implemented to output a periodic high-voltage pulse square wave signal (i.e., a target signal).

As can be seen in fig. 1, port 5' of 1021 is connected to port 5 of 1031 and port 6' of 1021 is connected to port 6 of 1031, wherein ports 6 and 6' are not directly grounded. Accordingly, 1021 forms a floating drive circuit across 1031 to drive on or off 1031.

Port 7' of 1022 is connected to port 7 of 1032 and port 8' of 1022 is connected to port 8 of 1032, wherein ports 8 and 8' are directly grounded, and thus 1022 does not form a floating drive circuit across 1031.

Port 10' of 1023 is connected to port 10 of 1033 and port 11' of 1023 is connected to port 11 of 1033, wherein ports 11 and 11' are directly grounded. Therefore, 1023 does not form a floating drive circuit across 1033.

Port 9' of 1024 is connected to port 9 of 1034 and port 17' of 1024 is connected to port 17 of 1034, wherein ports 9 and 9' are not directly grounded. Thus 1024 forms a floating drive circuit across 1034 to drive 1034 on or off.

And the frequency selecting circuit 104, wherein the left end and the right end of the frequency selecting circuit are respectively connected with one end of the multi-way switch circuit, the output end of the frequency selecting circuit is connected with the electromagnetic ultrasonic transducer, the frequency selecting circuit outputs a target signal according to the running state, and the target signal is used for exciting the electromagnetic ultrasonic transducer to generate ultrasonic waves in the structure to be detected.

In the embodiment of the invention, even initial signals in the first group of initial signals and even initial signals in the second group of initial signals generated by the signal generator are amplified by the multipath driving circuit, then the amplified even initial signals are used for controlling the running state of a bridge type switching circuit formed by the multipath switching circuit, and further, the output target signal of the frequency selection circuit is adjusted through the running state, wherein the output target signal is a high-voltage signal.

It should be noted that, in the embodiment of the present invention, the signal generator 101 may be referred to as a master circuit.

Specifically, the working principle of the 100 kW-level broadband electromagnetic ultrasonic excitation source shown in fig. 1 is as follows:

in the embodiment of the invention, the main control circuit is used for transmitting four paths of limited periodic square wave signals, wherein the transmitting frequency and the period of the periodic square wave signals are preset, the polarity of the periodic square wave signals output by the port 1 and the port 3 is the same, and the polarity of the periodic square wave signals output by the port 2 and the port 4 is the same. Square wave signals output by the port 1 and the port 3 respectively provide two paths of periodic square wave signals for the left arm high-end driving circuit 1021 and the right arm low-end driving circuit 1023; the square wave signals output by the port 2 and the port 4 are the same in polarity for the two paths of periodic square wave signals provided by the left arm low side driving circuit 1022 and the right arm high side driving circuit 1024, respectively, wherein the polarities of the square wave signals provided by the left arm high side driving circuit and the left arm low side driving circuit must be opposite, and the polarities of the square wave signals provided by the right arm high side driving circuit and the right arm low side driving circuit must be opposite.

The left arm high-end driving circuit 1021 is mainly used for amplifying power of one path of periodic square wave signal (namely, an initial signal output by the port 1) input into the left arm high-end driving circuit 1021, and directly loading the driving signal after power amplification into an input stage of the left arm high-end switch 1031 and the left end of the frequency selection circuit 104; the right arm low-side driving circuit 1023 is mainly configured to power amplify one of the periodic square wave signals (i.e., the initial signal output by the port 3), and directly load the power amplified driving signal between the input stage of the right arm low-side switch 1033 and the ground potential. The right arm high-end driving circuit 1024 is mainly configured to amplify power of one of the reverse polarity multiple periodic square wave signals (i.e., the initial signal output by the port 4), and directly load the power amplified driving signal to the input stage of the right arm high-end switch 1034 and the right end of the frequency selecting circuit 104; the left-arm low-side driving circuit 1022 is mainly configured to power amplify one of the reverse polarity multiple periodic square wave signals (i.e., the initial signal output by the port 2), and directly load the power amplified driving signal between the input stage of the left-arm low-side switch 1032 and the ground potential.

In the embodiment of the invention, the left arm high-end switch, the right arm high-end switch, the left arm low-end switch and the right arm low-end switch all comprise energy conversion devices. Because the polarity of the initial signal output by the port 1 is opposite to that of the initial signal output by the port 2, when the energy conversion devices in the left arm high-side switch and the right arm low-side switch are turned on, the energy conversion devices in the left arm low-side switch and the right arm high-side switch are turned off; conversely, when the energy conversion devices in the left arm high side switch and the right arm low side switch are off, the energy conversion devices in the left arm low side switch and the right arm high side switch are on.

Specifically, the high-level signal (i.e., one first voltage signal) output by the left arm high-side driving circuit 1021 controls the conduction of the energy conversion device in the left arm high-side switch 1031, so that the first terminal 12 of the frequency selection circuit 104 is conducted with the high-voltage power supply during this period. Meanwhile, the high-level signal (i.e., another first voltage signal) output by the right arm low-side driving circuit 1023 controls the energy conversion device in the right arm low-side switch 1033 to be turned on, so that the second terminal 13 of the frequency selection circuit 104 is turned on with the ground potential during this period.

When 1031 and 1033 are turned on, the frequency selection circuit loads the high voltage pulse from the energy conversion device in the left arm high-side switch and the low potential from the energy conversion device in the right arm low-side switch on the left and right sides of the frequency selection circuit network, respectively, and further, provides a high voltage signal (i.e., a target signal) to the output port of the electromagnetic ultrasonic transducer 105 from the output port of the frequency selection circuit.

The high-level signal (i.e., a second voltage signal) output by the right arm high-side driving circuit 1024 controls the energy conversion device in the right arm high-side switch 1034 to be turned on, so that the second terminal 13 of the frequency selection circuit 104 is turned on with the power supply circuit 106. Meanwhile, the high-level signal (i.e., another second voltage signal) output by the left arm low-side driving circuit 1022 controls the energy conversion device in the left arm low-side switch 1032 to be turned on, so that the first end 12 of the frequency selection circuit 104 is turned on with the ground potential during this period.

When 1032 and 1034 are turned on, the frequency selection circuit loads the high voltage pulse from the energy conversion device in the right arm high-side switch 1034 and the low potential output from the energy conversion device in the left arm low-side switch 1032 on the right and left input ends of the frequency selection circuit respectively, and provides the ground potential for the output port of the electromagnetic ultrasonic transducer from the output port of the frequency selection circuit.

As an alternative implementation of the embodiment of the present invention, fig. 1 may be equivalent to a circuit diagram as shown in fig. 2, and fig. 2 is a schematic diagram of another alternative 100 kW-level wide-frequency electromagnetic ultrasonic excitation source according to the embodiment of the present invention.

In an alternative embodiment of the present invention, each of the multiple switching circuits includes a field effect transistor, wherein a gate of the field effect transistor is connected to an output terminal of the driving circuit.

In another alternative embodiment of the present invention, the first switch set in the multi-way switch circuit includes a left arm high side switch and a right arm low side switch, the second switch set in the multi-way switch circuit includes a left arm low side switch and a right arm high side switch, wherein the left arm high side switch includes at least one first field effect transistor, the right arm low side switch includes at least one second field effect transistor, the left arm low side switch includes at least one third field effect transistor, and the right arm high side switch includes at least one fourth field effect transistor. That is, each switching circuit includes N field effect transistors, where the gate of each field effect transistor in the N field effect transistors is connected to the output terminal of the driving circuit, the drain of each field effect transistor is connected, the source of each field effect transistor is connected, and N is a positive integer greater than or equal to 1. That is, in the embodiment of the present invention, each driving circuit in the multi-path driving circuit may be formed by one field effect transistor, and may also be formed by connecting N field effect transistors in parallel.

In the 100 kW-level broadband electromagnetic ultrasonic excitation source shown in fig. 2, an example is described in which each switching circuit includes a field effect transistor, specifically, the high-side switch of the left arm is M1 in fig. 2, the low-side switch of the left arm is M2 in fig. 2, the high-side switch of the right arm is M3 in fig. 2, and the low-side switch of the right arm is M4 in fig. 2.

As can be seen from fig. 2, the drain electrode of each first field effect transistor (e.g., M1) is connected to a high voltage, and the source electrode of each first field effect transistor (e.g., M1) is connected to the first end of the frequency selection circuit; the source electrode of each second field effect transistor (e.g. M4) is grounded, and the drain electrode of each second field effect transistor (e.g. M4) is connected with the second end of the frequency selection circuit; the source electrode of each third field effect tube is grounded, and the drain electrode of each third field effect tube (for example, M2) is connected with the left end of the frequency selection circuit; the drain electrode of each fourth field effect tube (e.g. M3) is connected with high voltage, and the source electrode of each fourth field effect tube (e.g. M3) is connected with the right end of the frequency selection circuit. As can be seen from fig. 2, the sources of M1 and M3 are not directly grounded, but are connected to both ends of the frequency selective circuit, whereas the sources of M2 and M4 are directly grounded.

In another alternative embodiment of the present invention, the 100 kW-level broadband electromagnetic ultrasonic excitation source further comprises: the plurality of suppression circuits, one suppression circuit is connected with one path of field effect transistor, wherein, the first end of the suppression circuit is connected with the drain electrode of one path of field effect transistor, and the second end of the suppression circuit is connected with the source electrode of one path of field effect transistor.

As shown in fig. 2, the suppression circuit connected to the field effect transistor M1 is composed of a second capacitor C1, a resistor R1, and a diode D1; the suppression circuit connected with the field effect transistor M2 consists of a second capacitor C2, a resistor R2 and a diode D2; the suppression circuit connected with the field effect transistor M3 consists of a second capacitor C3, a resistor R3 and a diode D3; the suppression circuit connected with the field effect transistor M4 consists of a second capacitor C4, a resistor R4 and a diode D4.

In an alternative embodiment of the present invention, a frequency selection circuit includes: the electromagnetic ultrasonic transducer comprises a first capacitor and a transformer, wherein the first end of the first capacitor is connected with the output end of a left arm high-end switch, the second end of the first capacitor is connected with the first end of the primary side of the transformer, the second end of the primary side of the transformer is connected with the output end of a right arm high-end switch, and the secondary side of the transformer is connected with the electromagnetic ultrasonic transducer.

As shown in fig. 2, the frequency selection circuit includes a first capacitor C5 and a transformer TX, wherein a first end of the first capacitor C5 is connected to a source of the M1, a second end of the first capacitor C5 is connected to a first end of a primary side of the transformer TX, a second end of the primary side of the transformer is connected to a source of the M3, and a secondary side of the transformer is connected to a Load (Load).

The working principle of the 100 kW-level broadband electromagnetic ultrasonic excitation source shown in fig. 2 is as follows:

the first voltage signal output after the signal generator 101 and the left arm high-side driving circuit 1021 in fig. 1 are processed may be equivalent to a periodic square wave signal emitted from the driving source V1 in fig. 2. The second voltage signal output after the signal generator 101 and the left arm low side driving circuit 1022 in fig. 1 are processed may be equivalent to a periodic square wave signal emitted from the driving source V2. The second voltage signal output after the signal generator 101 and the right arm high-side driving circuit 1023 in fig. 1 are processed may be equivalent to the periodic square wave signal emitted by the driving source V3 in fig. 2; the first voltage signal output after the signal generator 101 and the right arm low-side driving circuit 1024 in fig. 1 are processed may be equivalent to a periodic square wave signal emitted from the driving source V4 in fig. 2. The driving source V1, the driving source V2, the driving source V3, and the driving source V4 are ideal driving sources.

In the 100 kW-level broadband electromagnetic ultrasonic excitation source shown in fig. 2, M1, M2, M3 and M4 are all selected as N-channel power field effect transistors. In fig. 2, the suppression circuit formed by D1, C1, R1 may be also referred to as a high-side spike suppression circuit for suppressing spike jitter caused by the switching characteristics of the energy conversion device M1. The suppression circuit formed by D2, C2, R2 may be referred to as a low-side spike suppression circuit for suppressing spike jitter caused by the switching characteristics of the energy conversion device M2. The suppression circuit formed by D3, C3, R3 may be referred to as a high-side spike suppression circuit for suppressing spike jitter caused by the switching characteristics of the energy conversion device M3. The suppression circuit formed by D4, C4, R4 may be referred to as a low-side spike suppression circuit for suppressing spike jitter caused by the switching characteristics of the energy conversion device M4.

As can be seen from fig. 2, the low voltage output terminal of V1 is floating-loaded at the left end of the frequency selective circuit 104 (i.e., the first end of the first capacitor C5) and the source electrode of the fet M1, the high voltage output terminal of V1 is loaded at the gate electrode of the N-channel power fet M1, and since the source electrode of M1 is not directly grounded, the driving source V1 forms a floating driving, and drives the fet M1 in a floating driving manner. When V1 outputs a high-level driving signal (i.e., a first initial signal) in the periodic square wave, a certain voltage difference (i.e., a first preset voltage) is formed between the gate and the source of the N-channel power fet M1, so that the drain and the source of the N-channel power fet M1 are turned on, and one end of C5 is turned on with the high-voltage power supply VH through the on-resistance of M1, so as to provide a high voltage for the left input end of the frequency selection circuit. Meanwhile, the low-voltage output end of the V4 is connected with the ground plane, the high-voltage output end of the V4 is loaded on the grid electrode of the N-channel power field effect transistor M4, a high-level driving signal in a periodic square wave output by the V4 forms a certain pressure difference (namely, a first preset voltage) between the grid electrode and the source electrode of the N-channel power field effect transistor M4, so that the drain electrode and the source electrode of the N-channel power field effect transistor M4 are conducted, the right input end of the frequency selection circuit is conducted with the ground potential through the on-resistance of the M4, and therefore lower potential is provided for the right input end of the frequency selection circuit, and at the moment, the field effect transistors M2 and M3 are in an off state.

In summary, during the period when M1, M4 are on, and M2, M3 are off, the high voltage at the left end and the low voltage at the right end of the frequency selection circuit will form a high voltage approximately 2 times the left end of the frequency selection network at the other end of the capacitor C5 and the primary 1 end of the transformer TX, and the primary 2 end of the transformer TX is a lower voltage, so that a high voltage slightly lower than the high voltage signal at the left input end of the frequency selection network is induced at the secondary side of the transformer.

As can be seen from fig. 2, the low voltage output end of V3 is floating-loaded on the right input end of the frequency selecting circuit (i.e. the second end of the primary side of the transformer TX) and the source electrode of the fet M3, the high voltage output end of V3 is loaded on the gate electrode of the N-channel power fet M3, and since the source electrode of M3 is not directly grounded, the driving source V3 forms a floating driving, and drives the fet M3 in a floating driving manner. When V3 outputs a high-level driving signal (i.e., a second initial signal) in the periodic square wave, a certain voltage difference (i.e., a second preset voltage) is formed between the gate and the source of the N-channel power fet M3, so that the drain and the source of the N-channel power fet M3 are turned on, and the right input terminal of the frequency selection circuit is turned on with the high-voltage power supply VH via the on-resistance of M3, thereby providing a high voltage for the right input terminal of the frequency selection circuit. Meanwhile, the low-voltage output end of the V2 is connected with a ground plane, the high-voltage output end of the V2 is loaded on the grid electrode of the N-channel power field effect transistor M2, a high-level driving signal in a periodic square wave output by the V2 forms a certain pressure difference (namely, a second preset voltage) between the grid electrode and the source electrode of the N-channel power field effect transistor M2, so that the drain electrode and the source electrode of the N-channel power field effect transistor M2 are conducted, the left end of the frequency selection circuit is conducted with the ground potential through the on-resistance of the M2, and therefore lower potential is provided for the left end of the frequency selection circuit, and at the moment, the field effect transistors M1 and M4 are in a closed state.

In summary, during the on period of M2 and M3, and the off period of M1 and M4, the high voltage at the right end and the low voltage at the left end of the frequency selection circuit will form the high voltages with equal potential at the 1 st end and the 2 nd end of the primary side of the transformer TX, so that the voltage difference induced at the secondary side of the transformer is approximately zero.

In an alternative embodiment of the present invention, the 100 kW-level broadband electromagnetic ultrasonic excitation source shown in fig. 1 may also be equivalent to the 100 kW-level broadband electromagnetic ultrasonic excitation source shown in fig. 3 to 7, and an embodiment of the present invention will be described with reference to fig. 3 to 7. Fig. 3 is a schematic diagram of a switching circuit and frequency selection circuit portion of another alternative 100 kW-level wide-frequency electromagnetic ultrasonic excitation source according to an embodiment of the invention. Fig. 4 is a schematic diagram of a left arm high-side drive circuit according to an embodiment of the invention. Fig. 5 is a schematic diagram of a low-side driving circuit of a left arm according to an embodiment of the invention. Fig. 6 is a schematic diagram of a right arm high-side drive circuit according to an embodiment of the invention. Fig. 7 is a schematic diagram of a right arm low side driving circuit according to an embodiment of the invention.

In an alternative embodiment of the present invention, each of the multiple driving circuits includes: the digital-analog isolation circuit is connected with the signal generator and is used for isolating the interference of a digital circuit in the signal generator on an analog circuit in a 100 kW-level broadband electromagnetic ultrasonic excitation source; the field effect transistor driving circuit is respectively connected with the one-path switching circuit digital-analog isolation circuit and is used for outputting voltage signals to the input end of the one-path switching circuit connected with the field effect transistor driving circuit, wherein the voltage signals are used for driving one-path field effect transistor to be turned on or turned off.

As can be seen from the above description, in the embodiment of the present invention, the multi-path driving circuit includes a left arm high-end driving circuit, a right arm high-end driving circuit, a left arm low-end driving circuit, and a right arm low-end driving circuit.

As shown in fig. 4, which is a schematic diagram of a high-end driving circuit of a left arm, as shown in fig. 4, the high-end driving circuit of the left arm includes: a digital-analog isolation circuit ISO_L_H and a field effect transistor driving circuit driver_L_H. The digital-analog isolation circuit ISO_L_H is connected with the signal generator through a pin 2 and is used for isolating the interference of a digital circuit in the amplified signal generator on a subsequent analog circuit; the digital-to-analog isolation circuit iso_l_h then inputs the first initial signal after isolation into the fet drive circuit driver_l_h via pin 6. Further, the fet driving circuit driver_l_h may output a first voltage signal to the fet connected thereto (i.e., the port shown as the drv_l_h network interface in fig. 3) via the pin 7 to drive the fet connected thereto to be turned on or off. As can be seen from fig. 4, pin 7 and pin 5 of the digital-analog isolation circuit iso_l_h are connected to pin 4, pin 5 and pin 6 of the field effect transistor driving circuit driver_l_h, and are all connected to interfaces shown by the network reference number floating_l_gnd, where the floating_l_gnd interface is a Floating ground interface for implementing Floating driving. It should be noted that, in the embodiment of the present invention, pin 4 of iso_l_h in fig. 4 is connected to the digital ground.

As shown in fig. 5, which is a schematic diagram of the low-side driving circuit of the left arm, as shown in fig. 5, the low-side driving circuit of the left arm includes: a digital-analog isolation circuit ISO_L_L and a field effect transistor driving circuit driver_L_L. The digital-analog isolation circuit ISO_L_L is connected with the signal generator through a pin 2 and is used for isolating the interference of a digital circuit in the amplified signal generator on a subsequent analog circuit; the digital-to-analog isolation circuit iso_l_l then inputs the second initial signal after isolation into the fet drive circuit driver_l_h via pin 6. Further, the fet driving circuit driver_l_l may output a second voltage signal to the fet connected thereto (i.e., the port shown as the drv_l_l network interface in fig. 3) via the pin 7 to drive the fet connected thereto to be turned on or off. As can be seen from fig. 5, pin 7 and pin 5 of the digital-to-analog isolation circuit iso_l_l are connected to pins 4, 5 and 6 of the fet drive circuit driver_l_h, which are all directly connected to analog ground. It should be noted that, in the embodiment of the present invention, pin 4 of iso_l_l in fig. 5 is connected to the digital ground.

As shown in fig. 6, which is a schematic diagram of a right arm high-end driving circuit, as shown in fig. 6, the right arm high-end driving circuit includes: a digital-analog isolation circuit ISO_R_H and a field effect transistor driving circuit DRIVER_R_H. The digital-analog isolation circuit ISO_R_H is connected with the signal generator through a pin 2 and is used for isolating the interference of a digital circuit in the amplified signal generator on a subsequent analog circuit; the digital-to-analog isolation circuit iso_r_h then inputs the second initial signal after isolation into the fet drive circuit driver_r_h via pin 6. Further, the fet driving circuit driver_r_h may output a first voltage signal to the fet connected thereto (i.e., the port shown as the drv_r_h network interface in fig. 3) through the pin 7 to drive the fet connected thereto to be turned on or off. As can be seen from fig. 6, pin 7 and pin 5 of the digital-analog isolation circuit iso_r_h are connected to pin 4, pin 5 and pin 6 of the field effect transistor driving circuit driver_r_h, and are all connected to interfaces shown by the network reference number floating_r_gnd, where the floating_r_gnd interface is a Floating ground interface for implementing Floating driving. It should be noted that, in the embodiment of the present invention, pin 4 of iso_r_h in fig. 6 is connected to the digital ground.

As shown in fig. 7, which is a schematic diagram of a right arm low-side driving circuit, as shown in fig. 7, the right arm low-side driving circuit includes: a digital-analog isolation circuit ISO_R_L and a field effect transistor driving circuit DRIVER_R_L. The digital-analog isolation circuit ISO_R_L is connected with the signal generator through a pin 2 and is used for isolating the interference of a digital circuit in the amplified signal generator on a subsequent analog circuit; the digital-to-analog isolation circuit iso_r_l then inputs the second initial signal after isolation into the fet drive circuit driver_r_h through pin 6. Further, the fet driving circuit driver_r_l may output a second voltage signal to the fet connected thereto (i.e., the port shown as the drv_r_l network interface in fig. 3) via the pin 7 to drive the fet connected thereto to be turned on or off. As can be seen from fig. 7, pin 7 and pin 5 of the digital-to-analog isolation circuit iso_r_l are connected to pins 4, 5 and 6 of the fet drive circuit driver_r_h, which are all directly connected to analog ground. It should be noted that, in the embodiment of the present invention, pin 4 of iso_r_l in fig. 7 is connected to the digital ground.

As shown in fig. 8, a schematic diagram of a signal generator is shown in fig. 8, where in an embodiment of the present invention, the signal generator is selected to be a Field Programmable Gate Array (FPGA). The four ports IO1 to IO4 of the FPGA are used for outputting four paths of signals, wherein the signals output through the ports IO1 and IO4 are the first group of initial signals, and the signals output through the ports IO2 and IO3 are the second group of initial signals. The network label in_l_h IN fig. 8 indicates that the port is connected to the network label in_l_h IN fig. 4, the network label in_l_l IN fig. 8 indicates that the port is connected to the network label in_l_l IN fig. 5, the network label in_r_h IN fig. 8 indicates that the port is connected to the network label in_r_h IN fig. 6, and the network label in_r_l IN fig. 8 indicates that the port is connected to the network label in_r_l IN fig. 7.

When the FPGA is used as the signal generator, the 4 IO ports shown in fig. 8 output 4 paths of periodic square wave signals, wherein the polarities of the signals output by the port IO1 and the port IO4 are the same, the polarities of the signals output by the port IO2 and the port IO3 are the same, and the periods of the square wave signals output by the ports IO1 to IO4 are the same, but the polarities of the square wave signals output by the ports IO1 and IO2 must be opposite.

As shown in fig. 3, the left arm high side switch includes a high side switching device, wherein the high side switching device (i.e., the energy conversion device) is selected as an N-channel power fet M1; the circuit composed of D1, C1, R1 is a high-side spike suppression circuit. The left arm low side switch comprises a low side switch device, wherein the low side switch device (i.e. the energy conversion device) is selected as a power field effect transistor M2 of an N channel; the circuit formed by D2, C2 and R2 is a low-end peak suppression circuit. The right arm high-side switch comprises a high-side switch device, wherein the high-side switch device (namely, an energy conversion device) is selected as a power field effect transistor M3 of an N channel; the circuit composed of D3, C3, R3 is a high-side spike suppression circuit. The right arm low side switch comprises a low side switch device, wherein the low side switch device (i.e. the energy conversion device) is selected as a power field effect transistor M4 of an N channel; the circuit formed by D4, C4 and R4 is a low-end peak suppression circuit; the capacitor C5 and the transformer TX form a frequency-selecting network; load is the electromagnetic ultrasonic sensor equivalent Load.

When IO1 and IO4 of the FPGA send periodic square wave signals with the same frequency and the same polarity, and IO2 and IO3 send square wave signals with the same frequency but opposite polarity to the signals sent by IO1, in order to calculate the output power of the whole circuit conveniently, in the embodiment of the invention, a high-power resistor with the power of 8Ω is selected as a load. When the signal frequency output by the FPGA is 1MHz and 8MHz, the output voltage of the Load is shown in fig. 9 and 10, respectively. As can be seen from fig. 9 and 10, the output voltage amplitude (i.e., the amplitude of the target signal) can be up to 920V, and the maximum transient output power can be up to 100kW. Therefore, by adopting the 100 kW-level broadband electromagnetic ultrasonic excitation source provided by the embodiment of the invention, the maximum power output can be 100kW, and instrument support is provided for improving the technology to in-service detection of high-temperature metal equipment.

In order to increase the output power of the 100 kW-level broadband electromagnetic ultrasonic excitation source, the full-bridge structure (namely, the high-end switch group and the low-end switch group) formed by the N-channel field effect transistors is adopted as an excitation source output stage, so that the output power of the 100 kW-level broadband electromagnetic ultrasonic excitation source can be increased to 100kW.

In order to improve the frequency of the output signal of the 100 kW-level broadband electromagnetic ultrasonic excitation source, the invention adopts a digital-analog isolation circuit to realize the isolation of the digital part and the analog part in the circuit, and simultaneously, in a full-bridge structure realized by adopting a high-speed driving circuit, the bandwidth of a high-voltage pulse signal output by the 100 kW-level broadband electromagnetic ultrasonic excitation source can be effectively expanded due to the rapid driving of the N-channel field effect transistor.

Summarizing, the 100 kW-level broadband electromagnetic ultrasonic excitation source provided by the embodiment of the invention mainly comprises the following advantages:

from the aspect of increasing output power, the embodiment of the invention adopts a full-bridge structure formed by N-channel field effect transistors as an excitation source output stage. Because the on-resistance of the N-channel field effect transistor is small, the power consumed in the switching circuit part is small, and therefore, the drain and the source of the N-channel field effect transistor can bear transient current of hundreds of amperes. Further, by setting the voltage of a proper power supply circuit, the output power of the 100 kW-level wide-frequency electromagnetic ultrasonic excitation source can be increased to be more than 100kW, so that the problem that the output power of the excitation source manufactured in the prior art is relatively smaller is solved.

From the angle of improving the frequency of the output signal, the digital-analog isolation circuit is adopted to isolate the digital circuit part from the analog circuit part, so that the interference of the digital signal to the analog circuit part can be effectively reduced, the field effect transistor high-speed driving circuit is adopted to realize the rapid driving of the N-channel field effect transistor in the full-bridge structure, and the bandwidth of the output high-voltage pulse signal can be effectively expanded.

The foregoing embodiment numbers of the present invention are merely for the purpose of description, and do not represent the advantages or disadvantages of the embodiments.

In the foregoing embodiments of the present invention, the descriptions of the embodiments are emphasized, and for a portion of this disclosure that is not described in detail in this embodiment, reference is made to the related descriptions of other embodiments.

In the several embodiments provided in the present application, it should be understood that the disclosed technology may be implemented in other manners. The above-described embodiments of the apparatus are merely exemplary, and the division of the units, for example, may be a logic function division, and may be implemented in another manner, for example, a plurality of units or components may be combined or may be integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be through some interfaces, units or modules, or may be in electrical or other forms.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in the embodiments of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.

The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied essentially or in part or all of the technical solution or in part in the form of a software product stored in a storage medium, including instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a removable hard disk, a magnetic disk, or an optical disk, or other various media capable of storing program codes.

The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims

1. A 100 kW-level broadband electromagnetic ultrasonic excitation source, comprising:

the signal generator is used for generating a first group of initial signals and a second group of initial signals, wherein the first group of initial signals and the second group of initial signals are signals with opposite polarities, the first group of initial signals comprise an even number of initial signals, and the second group of initial signals comprise an even number of initial signals;

the multipath driving circuit is connected with the signal generator and is used for amplifying the first group of initial signals and the second group of initial signals;

the multi-path switching circuit is connected with one path of the driving circuit, and the multi-path switching circuit adjusts the running state according to the amplified first group of initial signals and the amplified second group of initial signals, wherein the running state comprises on or off;

and the frequency selecting circuit is connected with the multi-path switch circuit through a first end and a second end of the frequency selecting circuit respectively, and an output end of the frequency selecting circuit is connected with the electromagnetic ultrasonic transducer, wherein the frequency selecting circuit outputs a target signal according to the running state, and the target signal is used for exciting the electromagnetic ultrasonic transducer to generate ultrasonic waves in a structure to be detected.

2. The 100 kW-level broadband electromagnetic ultrasonic excitation source of claim 1, wherein said multiplexing drive circuit comprises:

the first group of driving circuits are connected with the signal generator and are used for amplifying even initial signals in the first group of initial signals to obtain a first voltage signal group;

and the second group of driving circuits are connected with the signal generator and are used for amplifying even initial signals in the second group of initial signals to obtain a second voltage signal group.

3. The 100 kW-level broadband electromagnetic ultrasonic excitation source of claim 2, wherein the first set of drive circuits comprises a left arm high-side drive circuit and a right arm low-side drive circuit and the second set of drive circuits comprises a left arm low-side drive circuit and a right arm high-side drive circuit.

4. The 100 kW-level broadband electromagnetic ultrasonic excitation source of claim 2, wherein said multi-path switching circuit comprises:

the first switch group is connected with the first group driving circuit, and is conducted when the voltage value of the first voltage signal group loaded at the first end and the second end of the first switch group meets a first preset voltage;

And the second switch group is connected with the second group driving circuit, and is conducted when the voltage value of the second voltage signal group loaded at the first end and the second end of the second switch group meets a second preset voltage.

5. The 100 kW-level broadband electromagnetic ultrasonic excitation source of claim 4 wherein said first switch set comprises a left arm high-side switch and a right arm low-side switch, said second switch set comprises a left arm low-side switch and a right arm high-side switch, wherein said left arm high-side switch comprises at least one first fet, said right arm low-side switch comprises at least one second fet, said left arm low-side switch comprises at least one third fet, and said right arm high-side switch comprises at least one fourth fet.

6. The 100 kW-level broadband electromagnetic ultrasonic excitation source of claim 5 wherein the drain of each first fet is connected to a high voltage and the source of each first fet is connected to the left end of the frequency selective circuit; the source electrode of each second field effect transistor is grounded, and the drain electrode of each second field effect transistor is connected with the right end of the frequency selection circuit; the source electrode of each third field effect tube is grounded, and the drain electrode of each third field effect tube is connected with the left end of the frequency selection circuit; the drain electrode of each fourth field effect tube is connected with high level, and the source electrode of each fourth field effect tube is connected with the right end of the frequency selection circuit.

7. The 100 kW-level broadband electromagnetic ultrasonic excitation source of claim 5 wherein the frequency selective circuit comprises a first capacitor and a transformer, wherein a first end of the first capacitor is connected to the source of each first fet and the drain of each third fet, a second end of the first capacitor is connected to a first end of the primary side of the transformer, a second end of the primary side of the transformer is connected to the drain of the second fet and the source of the fourth fet, and a secondary side of the transformer is connected to the electromagnetic ultrasonic transducer.

8. The 100 kW-level broadband electromagnetic ultrasonic excitation source of claim 5, further comprising:

the first end of the high-voltage power supply circuit is connected with the drain electrode of each first field effect transistor and the drain electrode of each fourth field effect transistor respectively, the second end of the high-voltage power supply circuit is grounded, and the power supply circuit is used for providing high-voltage signals for the frequency selection circuit.

9. The 100 kW-level broadband electromagnetic ultrasonic excitation source of claim 5, wherein each of the multiple drive circuits comprises:

The digital-analog isolation circuit is connected with the signal generator and used for isolating the interference of a digital circuit in the signal generator on an analog circuit in the 100 kW-level broadband electromagnetic ultrasonic excitation source;

the field effect transistor driving circuit is respectively connected with the digital-analog isolation circuit of one path of switching circuit and is used for outputting voltage signals to the input end of the one path of switching circuit connected with the field effect transistor driving circuit, wherein the voltage signals are used for driving the one path of switching circuit to be turned on or turned off.

10. The 100 kW-level broadband electromagnetic ultrasonic excitation source of claim 9, further comprising:

the device comprises a plurality of suppression circuits, wherein one suppression circuit is connected with one path of field effect transistor, a first end of the suppression circuit is connected with a drain electrode of the path of field effect transistor, and a second end of the suppression circuit is connected with a source electrode of the path of field effect transistor.

11. The 100 kW-level broadband electromagnetic ultrasonic excitation source of claim 10 wherein each of said plurality of suppression circuits comprises a second capacitor, a resistor and a diode, wherein said second capacitor is connected in series with said diode in parallel with the source and drain of said field effect transistor and said resistor is connected in parallel across said diode.

12. The 100 kW-level wide-frequency electromagnetic ultrasonic excitation source of claim 8, wherein each of the plurality of switching circuits comprises N field-effect transistors, wherein the gate of each of the N field-effect transistors is connected to the output of the field-effect transistor driving circuit, the drain of each of the field-effect transistors is connected, the source of each of the field-effect transistors is connected, and N is a positive integer greater than or equal to 1.

13. A 100 kW-level broadband electromagnetic ultrasonic excitation source according to any one of claims 1 to 12 wherein said signal generator comprises a field programmable gate array.