Time-domain electromagnetic full-waveform transmitter based on active double clamping and control method

Abstract

The invention discloses a time domain electromagnetic full waveform transmitter based on active double clamping and a control method, the time domain electromagnetic full waveform transmitter is composed of a power supply, a combined clamping unit, a matching unit, a transmitting bridge circuit and a main controller, the combined clamping unit comprises a direct current voltage regulation clamping module and an energy feedback voltage regulation clamping module, and the power supply supplies power to the direct current voltage regulation clamping module and the energy feedback voltage regulation clamping module. Before transmitting, parameters are preset in the master controller, and the master controller drives a power device in the transmitting bridge circuit; at the rising edge, the direct current voltage regulation clamping module is connected with the transmitting bridge circuit through a power device, linear clamping of the rising edge is achieved, and time is controllable; at the falling edge, the energy-feedback voltage-regulating clamping module is connected with the transmitting bridge circuit through a diode, linear clamping along the falling edge is realized, and the time is controllable; when the tail section is launched, the matching unit is switched in, and tail overshoot is absorbed. The objective of the invention is to realize that the rising edge and the falling edge of the emission current are linear and the slope is controllable, and the flat top section and the tail section of one emission period are observed at the same time, so that the time-domain electromagnetic exploration efficiency is remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the field of geophysical exploration, relates to time-domain electromagnetic method exploration technology, and specifically relates to a time-domain electromagnetic full-waveform transmitter based on active double clamping and a control method thereof. Background Art

[0002] Time-domain electromagnetic method (TDEM) has become one of the important technologies in the field of underground material detection due to its significant advantages such as fast speed, high efficiency, wide detection range, and low cost. The principle of the existing time-domain electromagnetic bipolar trapezoidal wave transmitter is mainly to generate a bipolar trapezoidal wave current in the transmitting coil by the transmitter to excite a primary pulsed magnetic field. Then, during the intermittent period of the primary pulsed magnetic field, a detection device is used to measure the change of the electromagnetic field (secondary field) induced by the underground medium over time. By analyzing the characteristics of the secondary field, relevant information about the underground material can be obtained.

[0003] Most of the existing research focuses on the continuously adjustable clamping control of the falling edge of the trapezoidal wave to adjust the turn-off time of the trapezoidal wave, and thus achieve the response observation at different time scales. Some scholars have tried to perform linear clamping control on the rising edge of the trapezoidal wave. However, these schemes usually use the same clamping voltage source as the falling edge and do not design an adjustable clamping voltage source separately for the rising edge. Due to the non-adjustability of the clamping voltage source for the rising edge, the waveform is prone to overshoot or undershoot phenomena, which causes current fluctuations in the flat top section where the current should be maintained constant, and then continuously excites the primary magnetic field. This continuous current excitation not only makes the observation of the flat top section difficult, but also may affect the accuracy of the falling edge signal.

[0004] Therefore, realizing the linear control of the current for the rising edge and the falling edge and ensuring the stability of the current for the flat top section and the tail section has important research significance for accurate full-waveform observation in the flat top section and the tail section of the trapezoidal wave.

[0005] Chinese Patent CN105162352B discloses a bipolar steep pulse current source for inductive load and its control method. This method accelerates the rise of the current by supplementing energy storage, shortens the delay time of the inductive load current rise, makes the pulse current waveform close to an ideal step square wave, thereby improving the steepness of the rising edge and generating a strong magnetic field, and at the same time increasing the frequency of the current waveform. However, this technology only improves the steepness of the rising edge and does not achieve linear adjustable control of the rising edge.

[0006] Chinese Patent CN100337399C proposes a current pulse control method and device with the ability to improve the rising edge, and successfully realizes the linear adjustable control of the falling edge by accelerating the change of the rising edge and the falling edge through high-voltage clamping. However, this technology mainly focuses on the optimization of the falling edge and does not deeply explore the linear control and time adjustment of the rising edge.

[0007] Chinese Patent CN107979300A discloses a bipolar trapezoidal current large magnetic moment transmitter and its current generation method. This method uses a passive clamping technique to achieve a fast linear turn-off of the current falling edge, and at the same time achieves a fast linear boost of the rising edge, forming a bipolar trapezoidal current. In addition, a current overshoot suppression circuit is designed to effectively reduce the tail oscillation. However, the clamping voltage source for the rising edge of this scheme is not independently established, and the independent adjustment of the rise time and fall time cannot be achieved, and the waveform observation problem in the flat top section is not fully considered.

[0008] Chinese Patent CN116094319A proposes an electrical source large current slow turn-off emission control method based on DC chopping. By performing clamping control at the current falling edge, precise control at the falling edge of the trapezoidal wave is achieved. However, this technology only focuses on the control problem of the falling edge and does not effectively adjust the rising edge waveform. In addition, Chinese Patent CN115951413A discloses an electrical source induction-polarization targeted excitation method, which outputs two bipolar trapezoidal wave high-power emission currents with different turn-off times within one period to enhance the induction effect and polarization effect, thereby improving the exploration accuracy. But this method relies on two trapezoidal waves with different turn-off times, resulting in low efficiency.

[0009] In summary, although the existing technologies have made certain progress in the control of the rising edge or falling edge of the trapezoidal wave, there are still certain deficiencies in achieving independent linear regulation of the rising edge and falling edge currents, stability control of the waveform flat top section, and full waveform observation accuracy. Therefore, there is an urgent need for a new control method to achieve independent linear regulation of the rising edge and falling edge, ensure the high precision and stability of the current waveform, and thus provide a more accurate underground material detection ability for the time domain electromagnetic method. Summary of the Invention

[0010] To solve the above technical problems, the present invention provides a time domain electromagnetic full waveform transmitter and control method based on active double clamping. The system is based on technologies such as active double clamping technology, controllable H-bridge inverter technology, and tail damping absorption technology, realizing full waveform current emission with "both rising and falling are linear and adjustable, and the flat top and tail section currents are both constant", not only improving the quality of the emission current, but also effectively utilizing the data of the rising edge and flat top section, effectively improving the exploration efficiency, and having very important application significance for the transient electromagnetic exploration method.

[0011] The present invention is realized through the following technical solutions:

[0012] A time domain electromagnetic full waveform transmitter based on active double clamping includes: The transmitter includes a power supply, a combined clamping unit, a matching unit, a transmitting bridge circuit, and a main controller. Among them, the combined clamping unit includes a DC voltage regulating clamping module and a feed energy voltage regulating clamping module, both of which are powered by the power supply.

[0013] The emission bridge circuit includes power IGBT devices Q1, Q2, Q3, and Q4, diodes D1, D2, and D3, and an emission load coil. The series-connected power IGBT devices Q1 and Q2 are in parallel with the series-connected power IGBT devices Q3 and Q4. The two ends of the parallel connection form the first end and the second end of the emission bridge circuit. One end of the power supply is connected to the first end through the series-connected diodes D1 and D2, and the first end outputs through the diode D3. The second end of the emission bridge circuit is connected to the other end of the power supply. According to the switching signal of the main controller, the emission bridge circuit forms a bipolar current. One end of the emission coil is connected between the power IGBT devices Q1 and Q2, and the other end is connected between the power IGBT devices Q3 and Q4.

[0014] The matching unit is connected to the emission bridge circuit and includes a series connection of power IGBT devices Q5, Q6, and a resistive load. The emitters of the power IGBT devices Q5 and Q6 are both connected to the resistive load, and the two collectors are respectively connected between the power IGBT devices Q1 and Q2 and between the power IGBT devices Q3 and Q4. When the four power IGBT devices of the emission bridge circuit are turned off, the matching unit is connected to the circuit to absorb the tail overshoot of the emission current.

[0015] The main controller is a microprocessor. By controlling the switching devices of the emission bridge circuit, the power supply and the combined clamping unit supply power to the emission bridge circuit alternately.

[0016] The gates of the power IGBT devices are all controlled by the drive signals sent by the main controller to achieve the conduction and cutoff of the power devices.

[0017] The DC voltage regulation and clamping module is connected in parallel across the two ends of the input of the power supply. One end of the energy feedback voltage regulation and clamping module is connected to the output end of the diode D3, and the other end is connected to the second end of the emission bridge circuit.

[0018] Further, the DC voltage regulation and clamping module is designed based on the boost chopper technology. The DC voltage regulation and clamping module has four ports: input positive, input negative, output positive, and output negative. The input positive is connected to the positive pole of the power supply, the input negative and the output negative are both connected to the negative pole of the power supply, and the output positive is connected to the collector of the power device Q7. The emitter of the power device Q7 is connected between the diodes D1 and D2. When the emission current is rising, the power device Q7 is turned on to achieve high-voltage clamping, so that the bipolar emission current rises linearly according to the preset rising time. The output of the DC voltage regulation and clamping module is in a constant voltage mode, and the output voltage is continuously adjustable.

[0019] Furthermore, the energy-feeding voltage-regulating clamping module includes an energy storage capacitor and an energy-feeding unit. The energy storage capacitor is a large-capacity capacitor bank, which is connected in parallel to the emitter of diode D3 and power IGBT device Q4. The energy-feeding unit includes three resistors connected in series, one of which is a voltage-dividing resistor. The adjusting end of the voltage-dividing resistor is connected to the non-inverting input terminal of a comparator. The inverting input terminal of the comparator is grounded. The output terminal of the comparator is connected to the base of power device Q8. The emitter of power device Q8 is connected to the positive pole of the power supply through an energy-feeding resistor. The collector of power device Q8 is connected to the positive pole of the energy storage capacitor;

[0020] At the falling edge, the current flows into the energy storage capacitor through diode D3, and the energy storage capacitor continuously absorbs energy to form a voltage to clamp the current. When the voltage of the energy storage capacitor exceeds the preset value, power device Q8 conducts, and the energy of the energy storage capacitor is fed back to the power supply through the energy-feeding resistor. The function of the energy-feeding resistor is to control the energy-feeding current.

[0021] A time-domain electromagnetic full-waveform emission control method based on active double clamping. The full-waveform bipolar trapezoidal wave emission control steps for one bipolar period are as follows:

[0022] S1 Measure the power supply voltage value U s and the impedance R and inductive reactance L values in the emission bridge circuit, and preset parameters in the main controller;

[0023] S2 Based on the preset parameters including the power supply voltage value U s , impedance R and inductive reactance L, calculate the rise time t0, fall time t1 and the optimal current amplitude l b ; Automatically set the rise time t on = t0, fall time t off = t1, optimal current value I best = I b , where the reference current after power IGBT device Q1 and power IGBT device Q4 are turned on is positive, and the reference current direction after power IGBT device Q2 and power IGBT device Q3 are turned on is negative;

[0024] S3 In the rising edge stage, power IGBT device Q1, power IGBT device Q4 and power device Q7 are turned on in the positive half cycle, and power IGBT device Q2, power IGBT device Q3, power device Q7 are turned on in the negative half cycle. The DC voltage-regulating clamping module is connected to the emission bridge circuit, and the emission current linearly clamps and rises, and its voltage value is U c-on , and the duration is t on ;

[0025] S4 In the flat top section, the emission current value reaches I best, the power device Q7 is turned off, and the DC voltage regulation clamping module loses its function. Instead, the power supply provides energy to the emission bridge circuit through the diode D1 and the diode D2, and the current enters the flat-top constant value stage;

[0026] At the falling edge stage of S5, the power IGBT devices Q1 and Q4 are turned off in the positive half-cycle, and the power IGBT devices Q2 and Q3 are turned off in the negative half-cycle. The energy feedback voltage regulation clamping module is connected to the emission bridge circuit through the diode D3 to linearly clamp the emission current, and its voltage value is U c-off , and the duration is t off ;

[0027] At the tail end of the emission of S6, the power IGBT devices Q1, Q2, Q3, and Q4 are all turned off. The power IGBT device Q6 is turned on in the positive half-cycle, and the power IGBT device Q5 is turned on in the negative half-cycle, and the matching unit is cut in to absorb the overshoot at the current tail;

[0028] S7 performs the trapezoidal wave emission in the negative half-cycle, and repeats steps S3 to S6;

[0029] S8 realizes the emission of a bipolar trapezoidal wave current for one positive and negative cycle.

[0030] Furthermore, the optimal current value The rising-edge DC clamping module is connected to the emission bridge circuit at the beginning of the rise, and the voltage value calculation formula is:

[0031]

[0032] U in the formula c-on is the calculated optimal rising clamping voltage value;

[0033] The falling-edge energy feedback clamping module is used for current falling clamping, and the voltage value calculation formula is:

[0034]

[0035] U c-off is the calculated optimal falling clamping voltage value.

[0036] Compared with the existing methods, the current emission method provided by the present invention has the beneficial effects that: the present invention solves the problems of overshoot or undershoot in the rising edge of the bipolar trapezoidal wave of the traditional electromagnetic transmitter, and further utilizes the flat-top section, and additionally realizes the flat-top section observation on the basis of the tail section observation, significantly improving the efficiency of time-domain electromagnetic exploration. Description of the Drawings

[0037] Figure 1 is the schematic structural diagram of the full-wave transmitter system provided by the embodiment of the present invention;

[0038] Figure 2 is a schematic diagram of the unipolar full-waveform emission current provided by an embodiment of the present invention;

[0039] Figure 3 is a hardware topology diagram of the full-waveform transmitter according to an embodiment of the present invention;

[0040] Figure 4 is the drive signal of the controller device of the full-waveform transmitter according to an embodiment of the present invention;

[0041] Figure 5 is the emission current with linearized different rise times according to an embodiment of the present invention;

[0042] Figure 6 is the emission current with linearized different fall times according to an embodiment of the present invention. Specific Embodiments

[0043] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0044] A time-domain electromagnetic full-waveform transmitter based on an active double clamp, see Figure 1 Combined with Figure 2 As shown, based on the active double clamp technology, the controllable H-bridge inverter technology and the tail damping absorption technology, the time-domain electromagnetic full-waveform current emission is realized. The transmitter includes a power supply, a combined clamp unit, a matching unit, an emission bridge circuit and a main controller. The combined clamp unit includes a DC voltage regulation clamp module and a feed energy voltage regulation clamp module, both of which are powered by the power supply.

[0045] The emission bridge circuit includes power IGBT devices Q1, power IGBT device Q2, power IGBT device Q3, power IGBT device Q4, diodes D1, D2 and D3, and an emission load coil. The series-connected power IGBT devices Q1 and Q2 are in parallel with the series-connected power IGBT devices Q3 and Q4. The two ends of the parallel connection form the first end and the second end of the emission bridge circuit. One end of the power supply is connected to the first end through the series-connected diodes D1 and D2, and the first end is output through the diode D3. The second end of the emission bridge circuit is connected to the other end of the power supply; according to the switching signal of the main controller, the emission bridge circuit forms a bipolar current; one end of the emission coil is connected between the power IGBT devices Q1 and Q2, and the other end is connected between the power IGBT devices Q3 and Q4;

[0046] The matching unit is connected to the transmitting bridge circuit, including a power IGBT device Q5, a power IGBT device Q6 and a resistive load in series. The emitters of the power IGBT device Q5 and the power IGBT device Q6 are both connected to the resistive load, and the two collectors are respectively connected between the power IGBT device Q1 and the power IGBT device Q2 and between the power IGBT device Q3 and the power IGBT device Q4; when the four power IGBT devices of the transmitting bridge circuit are turned off, the matching unit is connected to the circuit to absorb the tail overshoot of the transmitting current.

[0047] The master controller is a microprocessor, which controls the switching devices of the transmitting bridge circuit to realize the power supply to the transmitting bridge circuit by the power supply and the combined clamping unit in turn; the gates of the power IGBT devices are all controlled by the driving signals issued by the master controller to realize the conduction and turn-off of the power devices.

[0048] The DC voltage regulating and clamping module is connected in parallel at both ends of the input terminal of the power supply. One end of the energy feedback voltage regulating and clamping module is connected to the output terminal of the diode D3, and the other end is connected to the second end of the transmitting bridge circuit.

[0049] Among them, the DC voltage regulating and clamping module is designed based on the boost chopper technology. The module has four ports: input positive pole, input negative pole, output positive pole and output negative pole; the input positive pole is connected to the positive pole of the power supply, the input and output negative poles are both connected to the negative pole of the power supply, and the output positive pole is connected to the collector of the power device Q7. When Q7 is turned on at the rising edge, high-voltage clamping is realized, so that the bipolar transmitting current rises linearly according to the preset rising time; the output of the module is in a constant voltage mode, and the output voltage is continuously adjustable.

[0050] The energy feedback voltage regulating and clamping module includes an energy storage capacitor and an energy feedback unit. The energy storage capacitor is a large-capacity capacitor bank, which is connected in parallel between the diode D3 and the emitter of the power IGBT device Q4. The energy feedback unit includes three resistors connected in series. One of the resistors is a voltage dividing resistor. The adjusting end of the voltage dividing resistor is connected to the non-inverting input terminal of a comparator. The inverting input terminal of the comparator is grounded. The output terminal of the comparator is connected to the base of the power device Q8. The emitter of the power device Q8 is connected to the positive pole of the power supply through an energy feedback resistor, and the collector of the power device Q8 is connected to the positive pole of the energy storage capacitor.

[0051] At the falling edge, the current flows into the energy storage capacitor through the diode D3, and the energy storage capacitor continuously absorbs energy to form a voltage to clamp the current; when the voltage of the energy storage capacitor exceeds the preset value, the power device Q8 is turned on, and the energy of the energy storage capacitor is fed back to the power supply through the energy feedback resistor. The function of the energy feedback resistor is to control the energy feedback current.

[0052] The time-domain electromagnetic full-waveform emission control method based on active double clamping provided by the embodiment of the present invention, see Figure 3 , in the full-waveform bipolar trapezoidal wave emission control steps of a positive and negative cycle are as follows:

[0053] S1 measures the power supply voltage value U s as well as the impedance R and inductive reactance L values in the transmitting bridge circuit, and preset parameters in the main controller;

[0054] S2 Based on the preset parameters including the power supply voltage value U s , impedance R and inductive reactance L, calculate the rise time t0, fall time t1 and the optimal current amplitude I b ; Automatically set the rise time t on of the transmitted current in the main controller off = t0, fall time t best = t1, optimal current value I b , where the reference current after the power IGBT devices Q1 and Q4 are turned on is positive, and the reference current direction after the power IGBT devices Q2 and Q3 are turned on is negative;

[0055] S3 In the rising edge stage, turn on the power IGBT devices Q1, Q4 and the power device Q7 in the positive half - cycle, turn on the power IGBT devices Q2, Q3 and the power device Q7 in the negative half - cycle, connect the DC voltage - regulating clamping module to the transmitting bridge circuit, and the transmitted current linearly clamps and rises, with its voltage value being U c-on , and the duration is t on ;

[0056] S4 In the flat - top section, the transmitted current value reaches I best , turn off the power device Q7, the DC voltage - regulating clamping module loses its function, and the power supply supplies energy to the transmitting bridge circuit through the diodes D1 and D2, and the current enters the flat - top constant - value stage;

[0057] S5 In the falling edge stage, turn off the power IGBT devices Q1 and Q4 in the positive half - cycle, turn off the power IGBT devices Q2 and Q3 in the negative half - cycle, connect the energy - feeding voltage - regulating clamping module to the transmitting bridge circuit through the diode D3, and linearly clamp the transmitted current, with its voltage value being U c-off , and the duration is t off ;

[0058] S6 At the end of the transmission, turn off all the power IGBT devices Q1, Q2, Q3 and Q4, turn on the power IGBT device Q6 in the positive half - cycle, turn on the power IGBT device Q5 in the negative half - cycle, and switch to the matching unit to absorb the overshoot at the end of the current;

[0059] S7 Perform the trapezoidal - wave transmission in the negative half - cycle, and repeat steps S3 to S6;

[0060] S8 realizes the emission of a bipolar trapezoidal wave current with positive and negative cycles.

[0061] Furthermore, for the time-domain electromagnetic full-waveform emission control method based on active double clamping, refer to Figure 4 , the optimal current amplitude When the actual value of the emission current at the rising time t0 is equal to I b , there will be no continuous slope change in the flat-top section of the current, presenting a stable constant value state; while when the actual value of the emission current at the rising time t0 is greater than I b , the current will have a continuous negative slope change, and the flat-top section shows a current decrease state; when the actual value of the emission current at the rising time t0 is less than I b , the current will have a continuous positive slope change, and the flat-top section shows a current increase state; whether it is a continuous positive slope or negative slope change, it will excite a primary field, causing signal aliasing between the primary field and the secondary field and making it unobservable.

[0062] In the present invention, the DC voltage regulation and clamping module is connected to the emission bridge circuit at the beginning of the rise, and its voltage value calculation formula is:

[0063]

[0064] U in the formula c-on is the calculated optimal clamping voltage value for the rise;

[0065] The energy feeding voltage regulation and clamping module is used for current drop clamping, and its voltage value calculation formula is:

[0066]

[0067] U c-off is the calculated optimal clamping voltage value for the drop.

[0068] The transmitter of the present invention and the provided control method can both achieve the same slope for rise and fall, that is, symmetric bipolar trapezoidal wave emission with the same excitation time for rise and fall; it can also achieve different slopes for rise and fall, that is, bipolar trapezoidal wave emission with different excitation times for conduction and turn-off.

[0069] According to the time-domain electromagnetic full-waveform emission control method based on active double clamping proposed by the present invention, relevant methods are simulated in software and verified. Here is a set of verification cases. The power supply voltage is 24V, the emission load has a resistance of 0.3 ohms and an inductance of 3mH. The boost module is based on BOOST boost technology, and the output voltage range is linearly adjustable from 48V to 72V. The capacitor is a 10000 μF electrolytic capacitor, and the clamping voltage value is linearly adjustable from 24V to 120V; considering parameters such as line stray resistance and diode voltage drop, the optimal current amplitude is about 16A at this time.

[0070] According to the simulation described above, refer to Figure 5 , by adjusting the boost adjustable clamping voltage value, three different rise times of 200 μs, 300 μs, and 500 μs with clamping voltage values of 70 V, 55 V, and 45.5 V respectively are achieved at the same emission current amplitude; refer to Figure 6 , by adjusting the energy feedback adjustable clamping voltage value, three different turn-off times of 90 μs, 140 μs, and 260 μs with clamping voltage values of 99 V, 72.5 V, and 50.1 V respectively are achieved at the same emission current amplitude;

[0071] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A time-domain electromagnetic full-wave transmitter based on an active double clamp, characterized in that: The transmitter includes a power supply, a combined clamping unit, a matching unit, a transmitting bridge circuit, and a main controller. Among them, the combined clamping unit includes a DC voltage regulating clamping module and an energy feeding voltage regulating clamping module, both of which are powered by the power supply; The transmitting bridge circuit includes power IGBT devices Q1, Q2, Q3, and Q4, diodes D1, D2, and D3, and a transmitting load coil. The series-connected power IGBT devices Q1 and Q2 are in parallel with the series-connected power IGBT devices Q3 and Q4. The two ends of the parallel connection form the first end and the second end of the transmitting bridge circuit. One end of the power supply is connected to the first end through the series-connected diodes D1 and D2, and the first end outputs through diode D3. The second end of the transmitting bridge circuit is connected to the other end of the power supply; according to the switching signal of the main controller, the transmitting bridge circuit forms a bipolar current; one end of the transmitting coil is connected between the power IGBT devices Q1 and Q2, and the other end is connected between the power IGBT devices Q3 and Q4; The matching unit is connected to the transmitting bridge circuit and includes the series connection of power IGBT devices Q5, Q6, and a resistive load. The emitters of the power IGBT devices Q5 and Q6 are both connected to the resistive load, and the two collectors are respectively connected between the power IGBT devices Q1 and Q2 and between the power IGBT devices Q3 and Q4; when the four power IGBT devices of the transmitting bridge circuit are turned off, the matching unit is connected to the circuit to absorb the tail overshoot of the transmitting current; The main controller is a microprocessor, and the switching devices of the transmitting bridge circuit are controlled by the main controller to realize the power supply to the transmitting bridge circuit by the power supply and the combined clamping unit alternately; The gates of the power IGBT devices are all controlled by the driving signals issued by the main controller to realize the conduction and cut-off of the power devices; The DC voltage regulating clamping module is connected in parallel across the two ends of the input of the power supply. One end of the energy feeding voltage regulating clamping module is connected to the output end of diode D3, and the other end is connected to the second end of the transmitting bridge circuit.

2. The time-domain electromagnetic full-waveform transmitter based on an active double clamp according to claim 1, characterized in that The DC voltage regulating clamping module is designed based on the boost chopper technology. The DC voltage regulating clamping module has four ports: input positive, input negative, output positive, and output negative; the input positive is connected to the positive pole of the power supply, the input negative and the output negative are both connected to the negative pole of the power supply, and the output positive is connected to the collector of the power device Q7. The emitter of the power device Q7 is connected between diodes D1 and D2. The power device Q7 is turned on during the rising edge of the transmitting current to realize high-voltage clamping, so that the bipolar transmitting current rises linearly according to the preset rising time; the output of the DC voltage regulating clamping module is in a constant voltage mode, and the output voltage is continuously adjustable.

3. The time-domain electromagnetic full-wave transmitter based on active double clamping according to claim 1, characterized in that, The energy feedback voltage clamping module includes an energy storage capacitor and an energy feedback unit. The energy storage capacitor is a large-capacity capacitor bank, which is connected in parallel to the emitter of diode D3 and power IGBT device Q4. The energy feedback unit includes three resistors connected in series, one of which is a voltage-dividing resistor. The adjustment terminal of the voltage-dividing resistor is connected to the non-inverting input terminal of a comparator. The inverting input terminal of the comparator is grounded. The output terminal of the comparator is connected to the base of power device Q8. The emitter of power device Q8 is connected to the positive power supply through an energy feedback resistor. The collector of power device Q8 is connected to the positive electrode of the energy storage capacitor; During the falling edge, the current flows into the energy storage capacitor through diode D3, and the energy storage capacitor continuously absorbs energy to form a voltage to clamp the current. When the voltage of the energy storage capacitor exceeds the preset value, power device Q8 conducts, and the energy of the energy storage capacitor is fed back to the power supply through the energy feedback resistor. The function of the energy feedback resistor is to control the energy feedback current.

4. A time-domain electromagnetic full-waveform emission control method for a time-domain electromagnetic full-waveform transmitter based on active double clamping according to any one of claims 1-3, characterized in that: The full-waveform bipolar trapezoidal wave emission control steps for one bipolar period are as follows: S1 Measure the power supply voltage value U s as well as the impedance R and inductive reactance L values in the transmitting bridge circuit, and preset parameters in the master controller; S2 calculates the rise time t0, fall time t1, and optimal current amplitude I based on preset parameters including the power supply voltage value U s , impedance R, and inductive reactance L; automatically set the rise time t b of the emission current in the main controller on = t0, fall time t off = t1, optimal current value I best = I b , where the reference current is positive after the power IGBT devices Q1 and Q4 are turned on, and the direction of the reference current is negative after the power IGBT devices Q2 and Q3 are turned on; In the rising edge stage of S3, the positive half-cycle conducts the power IGBT device Q1, the power IGBT device Q4, and the power device Q7, and the negative half-cycle conducts the power IGBT device Q2, the power IGBT device Q3, and the power device Q7. The DC voltage regulating and clamping module is connected to the emitter bridge circuit, and the emitter current linearly clamps and rises, and its voltage value is U c-on , with a duration of t on ; At the flat-top stage, the emission current value reaches I best , turn off the power device Q7, the DC voltage regulating and clamping module loses its function, and the power supply provides energy for the emission bridge circuit through diode D1 and diode D2, and the current enters the flat-top constant value stage; During the falling edge stage of S5, the positive half-cycle turns off the power IGBT devices Q1 and Q4, and the negative half-cycle turns off the power IGBT devices Q2 and Q3. The energy feedback voltage regulation and clamping module is connected to the transmitting bridge circuit through the diode D3 to linearly clamp the transmitting current, and its voltage value is U c-off , and the duration is t off ; S6 At the end of the emission, power IGBT devices Q1, Q2, Q3, and Q4 are all turned off. Power IGBT device Q6 is turned on during the positive half-cycle, and power IGBT device Q5 is turned on during the negative half-cycle. The matching unit is switched in to absorb the overshoot of the current tail; S7 The trapezoidal wave emission of the negative half-cycle is carried out, and steps S3 to S6 are repeated; S8 The bipolar trapezoidal wave current emission of one positive and negative cycle is achieved.

5. The time-domain electromagnetic full-waveform emission control method according to claim 4, characterized in that Optimal current value The rising-edge DC clamping module is connected to the transmitting bridge circuit at the beginning of the rise, and the voltage value calculation formula is: U in the formula c-on is the calculated optimal rising clamping voltage value; The falling-edge energy feedback clamping module is used for current falling-edge clamping, and the voltage value calculation formula is: U c-off is the calculated falling best clamping voltage value.

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