Ultrahigh-voltage constant-voltage clamping emission system for electrical source transient electromagnetic method

Abstract

The invention discloses an ultrahigh-voltage constant-voltage clamping transmitting system for an electrical source transient electromagnetic method, and belongs to the technical field of ultrahigh-voltage constant-voltage clamping. Comprising a main power supply, an auxiliary power supply, a clamping capacitor, a main switch bridge circuit, a clamping switch, a current sampling module, a peak holding module, a comparator and a controller. According to the invention, the waveform quality of the high-power electromagnetic transmitter can be effectively improved, and the transmitting performance is improved from two aspects of a rising edge and a falling edge. Development of a near-source electromagnetic method including SOTEM is promoted, and more powerful technical support is provided for a deep prospecting strategy.

Description

Technical Field

[0001] This invention relates to the field of ultra-high voltage constant voltage clamping technology, and more specifically to an ultra-high voltage constant voltage clamping launch system for the transient electromagnetic method of an electrical source. Background Technology

[0002] The Short-Offset Transient Electromagnetic Method (SOTEM) is a novel artificial source electromagnetic method proposed in recent years. It conducts detection in the near-source region and has theoretical advantages such as large detection depth and high resolution. SOTEM is more conducive to obtaining high resolution because its transmit / receive offset is small, allowing it to utilize more high-frequency components.

[0003] However, current mainstream electromagnetic detection equipment does not support wide-bandwidth transmission and observation, limiting the system's operating bandwidth to a relatively small range. This makes it difficult to fully translate the theoretical advantages of the method into detection advantages. Specifically: Firstly, current mainstream electric source transmitters are primarily designed for frequency domain methods, compatible with time domain methods in the far-source region. They do not specifically address factors such as turn-on / turn-off speed and linearity for the rising and falling edges of the transmitted waveform, thus failing to meet the transmission waveform requirements of the SOTEM method. Secondly, as a near-source method, SOTEM demands higher system operating bandwidth. The distortion-free transmission bandwidth of current mainstream electric source transmitters is generally less than 8 kHz, and even within this bandwidth, stable high-frequency, high-current transmission cannot be guaranteed, thus also failing to meet the requirements of the SOTEM method.

[0004] Therefore, how to provide an ultra-high voltage constant voltage clamping launch system for the transient electromagnetic method of electric sources is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides an ultra-high voltage constant voltage clamping launch system for the transient electromagnetic method of electrical sources, in order to solve the technical problems existing in the prior art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: An ultra-high voltage constant voltage clamping launch system for the transient electromagnetic method of an electrical source includes: Main power supply, used to provide the basic transmit voltage; A secondary power supply, wherein the output voltage of the secondary power supply is higher than the output voltage of the main power supply; A clamping capacitor, connected to the output terminal of the auxiliary power supply, is used to store the energy provided by the auxiliary power supply; The main switch bridge circuit is connected to the main power supply and is used to chop the DC current into a preset waveform and output the transmitting current to the load. A clamping switch is connected between the clamping capacitor and the main power supply bus to control the energy release and isolation of the clamping capacitor. The current sampling module is used to acquire the transmitted current signal flowing through the load in real time; A peak hold module, connected to the current sampling module, is used to record and hold the peak value of the transmitted current signal in the previous pulse cycle as a reference current value; A comparator, wherein the first input terminal of the comparator is connected to the peak hold module to obtain the reference current value, and the second input terminal of the comparator is connected to the current sampling module to obtain the real-time current signal; The controller is connected to the output of the comparator, the main switch bridge, and the control terminal of the clamping switch, respectively.

[0007] Furthermore, it also includes: a first unidirectional conductive device, the anode of the first unidirectional conductive device being connected to the positive output terminal of the main power supply, and the cathode of the first unidirectional conductive device being connected to the main switch bridge circuit.

[0008] Furthermore, it also includes: a second unidirectional conductive device, the anode of the second unidirectional conductive device being connected to the positive output terminal of the auxiliary power supply, the cathode of the second unidirectional conductive device being connected to one end of the clamping capacitor, and the other end of the clamping capacitor being grounded.

[0009] Furthermore, the controller is configured to: At the start of the transmission cycle, the main switch bridge is controlled to drive the load with the main power supply voltage, causing the current to rise. During the current rise phase, the clamping switch is turned on, so that the high voltage of the clamping capacitor is superimposed on the main power supply bus, jointly driving the load to accelerate the current rise slope. When the comparator detects that the real-time current signal has reached the reference current value, it outputs a toggle signal. In response to the flip signal, the controller controls the clamp switch to turn off, allowing the load to continue rising to a new peak value powered solely by the main power supply. The peak hold module updates the reference current value to the new peak value; During the current turn-off phase, the controller controls the main switch bridge to turn off to form a falling edge.

[0010] Furthermore, the main switch bridge circuit consists of four main IGBT bridge circuit switches, and the transmitted waveform output by the four main IGBT bridge circuit switches is a bipolar square wave or a coded waveform based on a bipolar square wave.

[0011] Furthermore, a unidirectional conductive device is connected in series between the clamping capacitor and the auxiliary power supply to prevent the clamping capacitor from reverse charging the auxiliary power supply.

[0012] Furthermore, the current sampling module is a sampling resistor or a current Hall sensor connected in series in the transmission circuit.

[0013] Furthermore, the load includes load R. LOAD and load L LOAD .

[0014] As can be seen from the above technical solution, compared with the prior art, this invention provides an ultra-high voltage constant voltage clamping transmitter system for the transient electromagnetic method of electrical sources. Under conditions where the output signal bandwidth reaches up to 25 kHz, it ensures that the output current can reach the preset value with virtually no distortion. The performance of this invention was tested and verified through simulation, laboratory testing, and field testing. The test results show that the transmitter using the ultra-high voltage constant voltage clamping technology proposed in this invention can meet the requirements of the SOTEM method, and will provide strong technical support for the subsequent research and promotion of the SOTEM method. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0016] Figure 1 This is a basic topology diagram of a traditional electromagnetic electric source transmitter; Figure 2 The principle of the ultra-high voltage control scheme for voltage feedback type active constant voltage clamping technology; Figure 3 The circuit schematic diagram of the system provided by this invention; Figure 4 This is a graph showing the transmitter's current-voltage characteristics. Figure 5 This is the first set of comparison images of time-domain waveforms; Figure 6 This is the second set of comparison images of time-domain waveforms; Figure 7 The figure shows the test results of the maximum transmission current of the system provided by the present invention at the same transmission frequency. Figure 8 This is a comparison chart of the measured time-domain waveforms; Figure 9 This is a comparison diagram of the measured frequency domain waveforms. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1: like Figure 3 As shown, this embodiment of the invention discloses an ultra-high voltage constant voltage clamping launch system for the transient electromagnetic method of an electric source, comprising: Main power supply P1 is used to provide the base transmit voltage; The ultra-high voltage auxiliary power supply P2 has an output voltage higher than that of the main power supply P1. Clamping capacitor C1; The first unidirectional conductive device D1 has its anode connected to the positive output terminal of the main power supply P1; The second unidirectional conductive device D2 has its anode connected to the positive output terminal of the ultra-high voltage auxiliary power supply P2, its cathode connected to one end of the clamping capacitor C1, and the other end of the clamping capacitor C1 grounded. The main switching bridge circuit includes four main IGBT bridge switches K1-K4, connected to the cathode of the first unidirectional conductive device D1 and the load (R). LOAD ,L LOAD Between ) is a function used to chop DC current into a preset waveform and output transmitting current to the load; Clamping switch K5 is connected between clamping capacitor C1 and the cathode of the first unidirectional conductive device D1, and is used to control the energy release and isolation of clamping capacitor C1; The current sampling module S1 is connected in series in the transmission circuit and is used to collect the transmission current signal flowing through the load in real time. The peak hold module, electrically connected to the current sampling module S1, is used to record and hold the peak value of the previous pulse cycle of the transmitted current signal as the reference current value I. ref ; Comparator U2 has its first input connected to a peak hold module to obtain the reference current value I. ref Its second input terminal is connected to the current sampling module S1 to obtain the real-time current signal; The controller is electrically connected to the output of comparator U2, the control terminals of main switch bridges K1-K4 and clamp switch K5, respectively. Specifically, the controller is configured as follows: At the start of the transmission cycle, the main switch bridge K1-K4 is activated to drive the load using the voltage provided by the main power supply P1, causing the current to rise. During the current rise phase, the clamping switch K5 is turned on, so that the high voltage energy stored in the clamping capacitor C1 is superimposed on the cathode of the first unidirectional conductive device D1 through the clamping switch K5, and together with the main power supply P1, it drives the load to accelerate the current rise slope. When comparator U2 detects that the real-time current signal has reached the reference current value I_ref, it outputs a toggle signal. In response to the flip signal, the controller controls the clamp switch K5 to turn off, cutting off the discharge circuit of the clamp capacitor C1, so that the load is powered separately by the main power supply P1 through the first unidirectional conductive device D1, and the current continues to rise to a new peak value. Peak hold module updates reference current value I ref For a new peak; During the current turn-off phase, the controller controls the main switch bridge K1-K4 to turn off to form a falling edge.

[0019] The first unidirectional conductive device D1 and / or the second unidirectional conductive device D2 are diodes.

[0020] The rated output voltage of the main power supply P1 is not higher than 1000V, and the rated output voltage of the ultra-high voltage auxiliary power supply P2 is not lower than 2500V.

[0021] The controller is further configured to keep the clamping switch K5 off during the first or first few pulse cycles after system startup, drive the load separately using the main power supply P1 to generate an initial transmit waveform, and have the peak value of this initial waveform recorded by the peak hold module as the initial reference current value I. ref .

[0022] The controller controls the main switch bridge K1-K4 to output a bipolar square wave or a coded waveform based on a bipolar square wave.

[0023] The controller controls the main switch bridges K1-K4, enabling the system to operate in a constant output power mode within the volt-ampere characteristic range of 1000V-50A to 400V-100A.

[0024] The current sampling module S1 is a sampling resistor or a current Hall sensor connected in series in the transmitting circuit.

[0025] The peak hold module is a sample-and-hold circuit.

[0026] Load R LOAD ,L LOAD This is a grounded conductor transmitting antenna used in the transient electromagnetic method for electrical sources.

[0027] Example 2: like Figure 1The diagram shows the basic topology of a traditional electromagnetic power source transmitter. The entire transmitter architecture can be divided into seven process modules, with P7 being the main IGBT bridge converter. It chops the DC power supply from P6 into the designed waveform and outputs it to the load. In other words, the final output waveform of the transmitter is mainly determined by the P7 section. Therefore, to overcome the limited bandwidth of existing equipment, this embodiment focuses on the P7 section.

[0028] Specifically, the transmission waveforms used in the electromagnetic method of electric source are mainly square waves and coded waveforms based on square waves. This embodiment takes the square wave as an example to discuss the large bandwidth optimization scheme of the transmitter P7 part. For a single square wave, it has three parts: rising edge, plateau period and falling edge. The rising edge represents the process of current conduction, which is the process of energy release. When the current conduction reaches a specified value, it enters the plateau period, which is the process of stable energy release. After reaching the specified turn-off time, the current turn-off forms the falling edge, which is the process of energy collection. The factor that restricts the width of the entire pulse is actually the speed of current conduction and turn-off. The faster both are, the narrower the width of the entire pulse can be compressed, thereby obtaining a larger transmission bandwidth. As shown in Equations (1) and (2), it describes the voltage across the load of the transmitting antenna, referred to as the load. U ,inductance L DC resistance R DC and current I Two fundamental formulas relating the frequencies. As can be seen from formula (1), when the frequency is low, R Z Mainly manifested in DC resistance R DC However, as the frequency increases, the proportion of inductive components in the transmitting cable will become larger and larger, leading to... R Z The current increases sharply. I It will be difficult to increase. Formula (2) reflects the current. I The rate of change of the voltage across the inductor is related to the voltage applied across the inductor. U L Proportional. During the launch process, as the current... I As it continues to increase, for a given... U , U L It will continue to decrease, leading to dI / dt It will continue to decrease, that is I The rate of change is slowing down. These two factors combined constitute the main theoretical challenge in simultaneously achieving high-frequency, high-current transmission. Because... L This is mainly related to methodological requirements, and in practice, it is difficult to significantly reduce these requirements through technical means; therefore, improvement is needed. I Performance improvements can only be achieved through enhancement or fine-tuning.U superior.

[0029] (1) (2) Currently, mainstream high-power transmitters do not have dedicated processing for their rising and falling edges; they are generally handled as follows: Figure 1 As shown in section P7, the voltage is directly inverted and output. That is... U L This refers to the emission voltage. Because load grounding conditions are inconsistent during field construction, and even for the same grounded load, grounding conditions can change over time, a constant emission current is required. U L Not consistent. Through analysis of... U L Control Enhancement I The waveform quality is mainly achieved through constant voltage clamping. There are two basic constant voltage clamping schemes. Passive constant voltage clamping technology results in excessive energy feedback on the falling edge at higher transmission frequencies, leading to significantly higher heat dissipation requirements and difficulty in improving transmission efficiency. Therefore, this embodiment will adopt an active constant voltage clamping scheme. According to formula (2), this is a traditional active constant voltage clamping scheme based on voltage feedback technology. This embodiment first analyzes whether the clamping voltage can be directly increased to 2500V ultra-high voltage based on this scheme.

[0030] like Figure 2 This is a schematic diagram of an ultra-high voltage control scheme for voltage feedback type active constant voltage clamping technology. In this diagram: P1 is the transmitter power supply, with a mainstream voltage of 1000V; K1 to K4 are the main IGBT bridge switches; K5 is the clamping switch; and R is within the dashed box on the left. LOAD and L LOAD The diagram shows the RL equivalent model of the actual transmitting antenna, with the dashed box on the right representing a logic conversion circuit. During operation, K5 temporarily stores the energy in the transmitting antenna (when turned off) in the energy storage capacitor C1. At the rising edge of the next pulse, this energy is released back into the transmitting antenna. The control logic for this action is as follows: Voltage divider resistors R1 and R2, along with comparator U2, are used to determine the voltage across C1, thus estimating whether the energy has been completely released. This, combined with the logic conversion circuit, generates a logic drive signal to drive switch K5 to perform the aforementioned operation.

[0031] Following the above logic, the rising edge is the energy harvesting process, and the falling edge is the energy release process. The energy harvested during the falling edge is stored in the capacitor and released during the next rising edge. Therefore, the energy used during the rising edge is basically equal to the energy harvested during the falling edge. For ease of understanding, the small amount of energy loss during the energy harvesting and release process is not considered here, because the rising and falling edges use the same voltage source, and their voltages are equal. Therefore, the current change slopes during the rising and falling edges are also basically the same. Thus, while increasing the rising edge speed, the falling edge speed will also increase. If the clamping voltage is directly increased from the current 1000V to 2500V, higher voltage-rated, high-power devices need to be selected. However, the parasitic parameters of these devices, such as parasitic capacitance and inductance, will be significantly worse than those of conventional low-voltage devices, easily introducing oscillations and spikes, making precise control too difficult and posing significant safety hazards. More importantly, for existing transmitters, the high-voltage capacitor voltage is the clamping voltage. The high-voltage capacitor is the specific device that performs clamping, and the logic voltage is commonly 1000V and 5V, that is, a voltage division ratio of 200:1. Increasing the capacitor voltage from 1000V to 2500V would require a voltage division ratio of 500:1. For comparators with fixed resolution, the bandwidth of the voltage divider circuit decreases as the division ratio increases due to parasitic parameters, making precise and timely voltage amplitude control impossible under high voltage conditions. Considering both factors, directly increasing the clamping voltage control using current voltage feedback schemes is difficult and also poses a safety risk.

[0032] See Figure 3 The present invention provides an ultra-high voltage constant voltage clamping transmission system for the transient electromagnetic method of an electric source, comprising: P1, D1, K1~K5, C1, R LOAD L LOAD The meanings of U1 and U2 are the same as in traditional circuits.

[0033] Specifically, the difference between this invention and existing technologies lies in the addition of an ultra-high voltage auxiliary power supply P2, a diode D2, a current sampling circuit S1, and a sample and hold circuit. The ultra-high voltage auxiliary power supply P2 and the diode are responsible for charging capacitor C1 and preventing C1 from reverse-charging P2, thus avoiding safety hazards. C1 is always maintained at a voltage of 2500V. The current sampling circuit is responsible for reading the current magnitude in the circuit, and the sample and hold circuit is responsible for recording and holding the current peak value.

[0034] Specifically, in terms of control, after the transmitter starts, it first outputs a current waveform driven by a bus voltage not exceeding 1000V. The current peak holding circuit records the peak value of this current waveform as a reference value. I refOn the next pulse, K5 is opened, causing C1 to discharge to the bus, raising the bus voltage to 2500V. This bus voltage drives the rising edge of the transmitting current on the load, making its rapid rise 2.5 times that at 1000V. As the current in the current pulse rises to... I ref At this point, the comparator flips, turning off K5 and restoring the bus voltage to 1000V. The current continues to rise until it reaches the falling edge trigger. The new peak current at this moment is recorded and used to update the reference value. I ref This process is repeated until the transmit current reaches the preset value and its rise time stabilizes. This strategy uses a combination of P2 and C1, which is similar to giving the original rising edge an extra "rise boost". Since the power of P2 is much lower than that of the main power supply P1, it essentially supports a higher instantaneous power consumption with a lower average power consumption. This design forms an ultra-high voltage constant voltage clamping technology, increasing the clamping voltage from the widely used below 1000V to 2500V, which can significantly compress the transmit pulse width, thereby increasing the bandwidth of the transmit signal.

[0035] Example 3: Based on the above principles, the main circuit of the system of this invention was modeled using LTspice software, and its performance was simulated and analyzed. For ease of comparison, a mainstream electric source transmitter in the prior art was introduced, and calculations were performed according to the parameters published in its operation manual. Its maximum output parameters are divided into two levels: 1000V-20A and 500V-40A. Unlike this two-level output mode, this invention operates in constant power mode within a given region.

[0036] like Figure 4 The figure shows the voltage-current characteristic curves of different transmitters. The area enclosed by the curve and the two coordinate axes represents the usable voltage-current range of the transmitter. The blue curve in the figure represents mainstream international transmitters, showing a clear two-tier configuration, while the red curve represents the self-developed system of this invention. It has an arc between 1000V-50A and 400V-100A. The product of the voltage and current values ​​at each point on the arc is a constant power value, indicating that the system can operate in constant power mode within this range. This mode makes the area enclosed by the red curve larger and the changes more subtle.

[0037] First, a comparison of time-domain waveform transmission performance was conducted. Since mainstream international systems only have two output levels, the self-developed system was compared to these two levels for relevant calculations. The first group was the 500V-40A level, assuming a transmitting cable inductive reactance of 3.0mH, a grounding resistance of 10Ω, a bipolar square wave with a 50% duty cycle, and a fundamental frequency of 25Hz. Under these conditions, the off-time length of the transmitted signal bandwidth was determined, and the results are as follows... Figure 5 As shown. Figure 5 (a) shows the simulation results of the mainstream international system, with a transmit current of 40A, a turn-off time of 204 μs, and an output power of 16 kW. Figure 5 (b) is a self-developed system. It maintains the same transmission current as the international mainstream system, and the output power is also 16 kW. However, the turn-off time is significantly reduced to 43 μs, and the qualitative estimate of the transmission signal bandwidth is about 5 times higher than that of the international mainstream system. Figure 5 (c) examines the maximum transmission performance of the self-developed system under given transmission conditions. Its transmission current is 63A, the system is in constant power mode, the transmission voltage is 630V, and the power reaches 39.7 kW. However, the turn-off time is only 67.6 μs, that is, under the condition of increasing the transmission current by about 150%, the turn-off time is compressed to about 1 / 3.

[0038] The second group is the 1000V-20A range, with all other parameters the same as the first group, except that the grounding resistance changes to 40 Ω. The comparison results are as follows: Figure 6 As shown. Figure 6 (a) shows the simulation results of the mainstream international system, with a transmit current of 20A, a turn-off time of 52 μs, and an output power of 16 kW. Figure 6 (b) is a self-developed system. It maintains the same transmit current as the international mainstream system, and the output power is also 16 kW. However, the turn-off time is significantly reduced to 20 μs, and the qualitative estimate of the transmit signal bandwidth is about 2.5 times higher than that of the international mainstream system. Figure 6 (c) The maximum transmission performance of the self-developed system under the aforementioned transmission conditions was examined. With a transmission current of 25A and a transmission voltage of 1000V, the turn-off time was only 25 μs. This means that with a transmission current increase of approximately 125%, the turn-off time was reduced to approximately half. The second set of test results shows that, with increasing grounding resistance, even under the same bus voltage constraints, the self-developed system can still achieve faster turn-off.

[0039] Next, we compare the frequency domain waveforms, specifically a bipolar square wave with a 100% duty cycle. As the fundamental transmission frequency increases, the transmission current will become distorted. Essentially, within a given pulse width, the transmission current has not yet reached the set current value before polarity reverses. Therefore, we use the highest frequency at which the transmission current can still be pulled up to the set current value, termed the "critical frequency," as the comparison point. Figure 7 As shown in (a), the simulation results of the frequency domain waveform of the output of the mainstream international transmitter are used. The transmitter is set to 500V-40A, with an inductive reactance of 1.5 mH and a grounding resistance of 20 Ω. According to its volt-ampere characteristics, the system voltage is 500V, the current is 25A, and the power is 12.5 kW. The simulation results show that the critical frequency under this condition is 1.25 kHz. Figure 7(b) is the self-developed system, with a grounding resistance of 20 Ω. It maintains the same transmission parameters as the international mainstream system, namely, voltage 500V, current 25A, and frequency 1.25 kHz. It can be seen that under the control of ultra-high voltage constant voltage clamping, the rising and falling edges of the self-developed system exhibit a steep linear process. This is significantly different from the exponential change process exhibited by the rising and falling edges of the international mainstream transmitters. As a result, under the current parameters, the self-developed system still has a relatively long plateau at the top of the transmitted pulse, indicating that the current frequency has not yet reached the critical frequency of the self-developed system. Figure 7 (c) shows the maximum transmission current test of the self-developed system at the same transmission frequency. It can be seen that the system is in constant power mode at this time, with a transmission voltage of 894V and a current of 44.5A, which is 178% higher than the international mainstream system, and the waveform is good. Figure 7 (d) is the critical frequency of the self-developed system under the same transmission conditions. Since the rising and falling edges of the self-developed system have high linearity, the waveform will degenerate into a triangular wave when the critical frequency is formed. At this time, the transmission voltage is 900V, the current is 43A, and the critical frequency is 8kHz. Both the current and critical frequency indicators are much higher than those of the mainstream international transmitters.

[0040] To further verify the performance of the self-developed transmitter, the research group conducted system testing in Lingwu, Ningxia in early July 2022. A 0.8 km transmission cable was laid with a grounding resistance of 46.7 Ω. First, the time-domain waveform was tested, with a transmission current of 20 A, transmitting a bipolar square wave with a 50% duty cycle and a fundamental frequency of 25 Hz. Transmissions were conducted using both international mainstream systems and the self-developed system, and the turn-off waveform was recorded using an oscilloscope. Figure 8 As shown, where Figure 8 (a) is the mainstream international system, whose actual transmission current can only reach 17A and the turn-off time is 52.2 μs; Figure 8 (b) is a self-developed system with an emission current of 22A and a turn-off time of 23.44 μs, which is significantly better than the mainstream international system. Figure 9 The test results are for the waveform in the transmission frequency domain. Figure 9 (a) is the critical frequency waveform of the mainstream international system, with a transmission current of 15A and a critical frequency of 1.25 kHz. Figure 9 (b) shows the critical frequency waveform of the self-developed system. The transmitting current is 20A and the critical frequency is 8.23 ​​kHz. The waveform quality of the self-developed system is significantly higher than that of the mainstream international system. This result is basically consistent with the simulation test.

[0041] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0042] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An ultra-high voltage constant voltage clamped launch system for use in electrical source transient electromagnetic methods, characterized by, The application relates to a current source, which comprises: a main power supply for providing a basic emission voltage; a sub-power supply, the output voltage of which is higher than that of the main power supply; a clamping capacitor connected to the output end of the sub-power supply and used for storing energy provided by the sub-power supply; a main switch bridge connected to the main power supply and used for chopping direct current into a preset waveform and outputting emission current to a load; a clamping switch connected between the clamping capacitor and the bus of the main power supply and used for controlling the energy release and isolation of the clamping capacitor; a current sampling module used for collecting emission current signals flowing through the load in real time; a peak holding module connected to the current sampling module and used for recording and holding the peak value of a previous pulse period of the emission current signals as a reference current value; a comparator, the first input end of which is connected to the peak holding module to obtain the reference current value, and the second input end of which is connected to the current sampling module to obtain real-time current signals; a controller connected to the output end of the comparator, the main switch bridge and the control end of the clamping switch respectively.

2. The ultra-high voltage constant voltage clamping launch system for transient electromagnetic method of electric power source according to claim 1, characterized in that, The application further comprises: a first unidirectional conductive device, the anode of which is connected to the positive output end of the main power supply, and the cathode of which is connected to the main switch bridge.

3. The ultra-high voltage constant voltage clamping launch system for the electrical source transient electromagnetic method according to claim 1, characterized in that, The application further comprises: a second unidirectional conductive device, the anode of which is connected to the positive output end of the sub-power supply, and the cathode of which is connected to one end of the clamping capacitor, and the other end of the clamping capacitor is grounded.

4. The ultra-high voltage constant voltage clamping launch system for the electrical source transient electromagnetic method according to claim 1, characterized in that, The controller is configured to: control the main switch bridge to drive the load with the main power supply voltage at the beginning of an emission period, so that the current rises; control the clamping switch to turn on at the current rising stage, so that the high voltage of the clamping capacitor is superimposed on the bus of the main power supply, and the bus and the clamping capacitor jointly drive the load to accelerate the current rising slope; output a flip signal when the comparator detects that the real-time current signal reaches the reference current value; the controller controls the clamping switch to turn off in response to the flip signal, so that the load is separately powered by the main power supply to continue rising to a new peak value; the peak holding module updates the reference current value to the new peak value; the controller controls the main switch bridge to turn off at the current turn-off stage to form a falling edge.

5. The ultra-high voltage constant voltage clamping launch system for electrical source transient electromagnetic method according to claim 1, wherein, The main switch bridge is composed of four main IGBT bridge switches, and the emission waveform output by the four main IGBT bridge switches is a bipolar square wave or a coded waveform based on the bipolar square wave.

6. The ultra-high voltage constant voltage clamping launch system for electrical source transient electromagnetic method of claim 1, wherein, A unidirectional conductive device is connected in series between the clamping capacitor and the sub-power supply, which is used for preventing the clamping capacitor from reversely charging the sub-power supply.

7. The ultra-high voltage constant voltage clamping launch system for electrical source transient electromagnetic method of claim 1, wherein, The current sampling module is a sampling resistor or a current Hall sensor connected in series in an emission loop.

8. The ultra-high voltage constant voltage clamping launch system for electrical source transient electromagnetic method of claim 1, wherein, The load comprises a load R LOAD and a load L LOAD .

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