Isolation triggered kilovolt level high-energy pulse discharge circuit and control method thereof

Abstract

This invention discloses an isolated-triggered kilovolt-level high-energy pulse discharge circuit and its control method, relating to the field of high-voltage pulse power technology. The circuit includes a low-voltage trigger input interface, a control unit, an optocoupler isolation drive unit, a transistor current enhancement unit, an energy storage capacitor, an IGBT power switch module, an electromagnetic pulse load, a composite protection network, and a fault detection and rapid shutdown unit. After the low-voltage trigger signal is validated, it undergoes opto-isolation, current amplification, and waveform shaping sequentially to drive the IGBT power switch module to conduct, enabling the energy storage capacitor to release pulse energy to the electromagnetic pulse load. The composite protection network suppresses overshoot voltage, voltage oscillation, and residual charge through diode clamping and freewheeling, RC absorption, gate protection, and residual charge discharge. This invention improves the isolation, stability, and safety of the kilovolt-level high-energy pulse discharge process.

Description

Technical Field

[0001] This invention relates to the field of high-voltage pulse power and power semiconductor device drive control technology, specifically to an isolated-triggered kilovolt-level high-energy pulse discharge circuit and its control method. Background Technology

[0002] High-energy pulse discharge circuits typically use a high-voltage power supply to charge an energy storage capacitor. Upon receiving a trigger signal, the circuit controls a power switching device to conduct, causing the energy storage capacitor to release electrical energy to the electromagnetic pulse load within a short period of time, thus forming a high-voltage, high-current transient pulse. This type of circuit can be used in underwater sound source equipment such as electromagnetic pulse buzzers, where a pulsed current drives an inductor coil to generate a transient electromagnetic force, thereby forming an acoustic pulse for seismic detection. Existing buzzer equipment typically uses a few kilovolts of operating voltage and thyristor control, which suffers from problems such as high operating voltage, insufficient switching control flexibility, and high requirements for equipment size and cable insulation.

[0003] To reduce operating voltage and improve switching control performance, IGBTs can be used as power switches between the energy storage capacitor and the electromagnetic pulse load. Since the trigger signal output by the controller is typically a low-voltage, low-current signal, while the IGBT operates in a kilovolt-level, high-peak-current pulse environment, electrical isolation is required between the low-voltage control side and the high-voltage power side. Sufficient charging and discharging current must also be provided to the IGBT gate. If only ordinary optocouplers are used or the IGBT is directly driven by the controller, insufficient drive current and a slow switching edge can easily increase the IGBT's switching losses. Furthermore, interference generated on the high-voltage power side may be transmitted to the low-voltage control side, affecting triggering stability.

[0004] Electromagnetic pulse loads exhibit significant inductive characteristics, with a rapid current rise during the discharge of the energy storage capacitor. During IGBT turn-on and turn-off, they are susceptible to the load inductance and parasitic inductance of the connecting conductors, resulting in voltage spikes, voltage oscillations, and overshoot. Existing circuits typically employ freewheeling diodes, clamping devices, or RC snubber circuits. However, without coordinated design between protection branches specifically addressing the 100-joule-level pulse discharge process, it may be difficult to simultaneously address pulse energy release, inductive current freewheeling, and power device overvoltage protection. Furthermore, the IGBT gate may be affected by transient coupling voltages during switching, leading to gate overvoltage or false turn-on. After the pulse discharge ends, residual charge may remain at the ends of the electromagnetic pulse load, increasing safety risks during equipment shutdown and maintenance.

[0005] When overcurrent, overvoltage, drive malfunction, or pulse discharge circuit abnormality occurs in the power switch, if the controller only makes a software judgment before shutting down the IGBT, the delay in fault detection and control processing may cause the power device to continue to withstand significant current and power loss. If the energy storage capacitor charging is not stopped or subsequent triggering is not prohibited after the fault shutdown, repeated triggering or continued energy storage under fault conditions may occur. Therefore, it is necessary to provide a high-energy pulse discharge circuit suitable for kilovolt and 100joule level electromagnetic pulse loads, in which low-voltage trigger isolation, gate drive enhancement, IGBT pulse discharge, diode clamping and freewheeling, RC absorption, gate protection, residual charge discharge, and rapid fault shutdown work together to improve the stability, safety, and reliability of the pulse discharge process. Summary of the Invention

[0006] The purpose of this invention is to provide an isolated-triggered kilovolt-level high-energy pulse discharge circuit and its control method to solve the problems of insufficient isolation between the low-voltage trigger side and the high-voltage power side, insufficient IGBT gate drive current, easy generation of voltage spikes and oscillations during inductive load discharge, and inability to turn off the power switch and stop the charging of the energy storage capacitor in time under fault conditions in existing electromagnetic pulse discharge circuits.

[0007] To achieve the above objectives, the present invention adopts the following technical solution.

[0008] This invention provides an isolated-triggered kilovolt-level high-energy pulse discharge circuit, including a low-voltage trigger input interface, a control unit, an optocoupler isolation drive unit, a transistor current enhancement unit, an energy storage capacitor, an IGBT power switch module, an electromagnetic pulse load, a composite protection network, and a fault detection and fast shutdown unit.

[0009] The low-voltage trigger input interface, control unit, optocoupler isolation drive unit, transistor current enhancement unit, and IGBT power switch module are connected in sequence. The low-voltage trigger input interface is used to receive low-voltage trigger signals output from external devices and transmit the low-voltage trigger signals to the control unit. The control unit judges the validity of the low-voltage trigger signal and outputs a drive control signal to the optocoupler isolation drive unit when the triggering conditions are met.

[0010] The optocoupler isolation drive unit is used to electrically isolate the low-voltage control side where the control unit is located from the high-voltage power side where the IGBT power switch module is located, so as to reduce the impact of high-voltage side switching transients and electromagnetic interference on the low-voltage control side. The trigger signal after optocoupler isolation is input to the transistor current enhancement unit, which amplifies the current and shapes the waveform to improve the gate charging and gate discharging capabilities of the IGBT power switch module.

[0011] In one embodiment, the low-voltage trigger input interface includes a trigger signal input terminal, an input current-limiting resistor, an input filter capacitor, and a trigger status indicator circuit. The trigger signal input terminal is connected to the trigger input terminal of the control unit via the input current-limiting resistor, the input filter capacitor is connected between the trigger input terminal of the control unit and the low-voltage side reference ground, and the trigger status indicator circuit is connected to the trigger signal input terminal to indicate the input status of the low-voltage trigger signal.

[0012] In one embodiment, the optocoupler isolation drive unit includes an optocoupler driver and low-voltage side power supply circuits and isolation side power supply circuits respectively disposed on the input side and output side of the optocoupler driver. The input terminal of the optocoupler driver is connected to the control unit, and the output terminal of the optocoupler driver is connected to the transistor current enhancement unit, so that there is no direct conductive connection between the control unit and the IGBT power switching module.

[0013] The transistor current enhancement unit includes a first driving transistor and a second driving transistor, which together form a push-pull driving circuit. The input terminal of the push-pull driving circuit is connected to the output terminal of the optocoupler driver, and the output terminal of the push-pull driving circuit is connected to the gate terminal of the IGBT power switch module via a gate driving resistor.

[0014] When the optocoupler driver outputs a turn-on signal, the push-pull drive circuit provides gate charging current to the gate of the IGBT power switch module, enabling the IGBT power switch module to turn on quickly. When the optocoupler driver outputs a turn-off signal, the push-pull drive circuit provides a gate discharge path for the gate of the IGBT power switch module, enabling the gate charge to be released quickly and the IGBT power switch module to turn off.

[0015] Furthermore, the transistor current enhancement unit includes a gate charging branch and a gate discharging branch that are separate from each other. The gate charging branch and the gate discharging branch each include a unidirectional conducting device and a gate driving resistor. The gate driving resistor in the gate charging branch and the gate driving resistor in the gate discharging branch have different resistance values ​​to adjust the turn-on speed and turn-off speed of the IGBT power switching module, respectively.

[0016] The energy storage capacitor is connected between the DC positive bus and the DC negative bus to store electrical energy input from an external charging power supply. The IGBT power switch module is connected in the pulse discharge circuit formed by the energy storage capacitor and the electromagnetic pulse load, and is used to control the energy storage capacitor to release pulse electrical energy to the electromagnetic pulse load according to the trigger signal after electrical isolation, current amplification and waveform shaping.

[0017] In one embodiment, the energy storage capacitor is a pulse energy storage capacitor, or a group of energy storage capacitors connected in parallel. The equivalent capacitance of the energy storage capacitor is 250-600μF, the rated withstand voltage is not less than 1.2kV, the charging voltage is 700-1000V, and the energy stored in a single charge is 60-300J.

[0018] Preferably, the energy storage capacitor has an equivalent capacitance of 400μF, a rated withstand voltage of 1.2kV, and a charging voltage of 1000V. When the energy storage capacitor is charged to 1000V, the stored energy is approximately 200J. The electromagnetic pulse load is a Boomer load, including an electromagnetic pulse transmitting coil for generating a pulsed magnetic field.

[0019] The IGBT power switching module includes a first IGBT, a second IGBT, and a first freewheeling diode and a second freewheeling diode connected in anti-parallel to the first IGBT and the second IGBT, respectively. The main current paths of the first IGBT and the second IGBT are connected in series between the DC positive bus and the DC negative bus, and the connection node between the first IGBT and the second IGBT forms the midpoint of a half-bridge.

[0020] One end of the electromagnetic pulse load is connected to the midpoint of the half-bridge, and the other end is connected to either the DC positive bus or the DC negative bus. The first IGBT and the second IGBT control the conduction and cutoff of the pulse discharge circuit according to the drive signal. At least one of the first freewheeling diode and the second freewheeling diode is used to provide a release path for the inductive current in the electromagnetic pulse load after the corresponding IGBT is turned off.

[0021] The energy storage capacitor, IGBT power switching module, and electromagnetic pulse load are arranged adjacently and form a partial pulse discharge circuit through copper busbars, copper strips, laminated busbars, or rigid conductive connectors. This partial pulse discharge circuit is separate from the charging cable connected to the external charging power supply, so that the main pulse current generated by the discharge of the energy storage capacitor flows primarily between the energy storage capacitor, IGBT power switching module, and electromagnetic pulse load, without passing through the charging cable connected to the external charging power supply.

[0022] The composite protection network includes a diode clamping and freewheeling network, an RC absorption circuit, a gate protection unit, and a residual charge discharge unit.

[0023] The diode clamping and freewheeling network and the RC snubber circuit are respectively connected to at least one of the IGBT power switching module and the electromagnetic pulse load. The diode clamping and freewheeling network is used to form an overvoltage release path during the IGBT power switching module's turn-on or turn-off process, and to provide a freewheeling path for the residual inductive current in the electromagnetic pulse load after the IGBT power switching module is turned off.

[0024] In one embodiment, the diode clamping and freewheeling network includes multiple high-voltage diodes, which are connected in series and / or in parallel to form a voltage clamping branch and an inductive current freewheeling branch. The clamping voltage of the voltage clamping branch is higher than the maximum charging voltage of the energy storage capacitor and lower than the rated withstand voltage of the IGBT power switching module, so as to conduct and limit the voltage across the IGBT power switching module when an overshoot voltage occurs in the pulse discharge circuit.

[0025] In one specific embodiment, the diode clamping and freewheeling network includes high-voltage diodes D11 to D18. D11 to D18 form a high-voltage clamping and freewheeling protection network according to their connection direction and position, used to suppress voltage spikes generated during power switching and to provide a release path for inductive current in electromagnetic pulse loads.

[0026] Additionally, the voltage clamping branch includes D11, D12, D13, and D14. D11, D12, and D13 are configured according to... Figure 5 The polarities shown are connected in series in the same direction, and D14 is connected in series with D11, D12, and D13 in opposite directions. Specifically, one end of D11 forms the first end of the voltage clamping branch, the other end of D11 is connected to D12, the other end of D12 is connected to D13, the other end of D13 is connected to D14, and the other end of D14 forms the second end of the voltage clamping branch; the first and second ends of the voltage clamping branch are respectively connected to... Figure 5 The corresponding protection node connections are shown.

[0027] When the pulse discharge circuit is operating normally and the voltage across the voltage clamping branch does not reach the operating condition, the voltage clamping branch does not bear the main pulse current. When the IGBT power switch module 6 is turned on or off, causing a transient overvoltage between the corresponding protection nodes, the voltage clamping branch forms a transient current release path to limit the peak voltage between the corresponding protection nodes.

[0028] The inductive current freewheeling branch includes D15, D16, D17, and D18. D15, D16, and D17 are arranged according to... Figure 5 The polarities shown are connected in series in the same direction, with D18 connected in series with D15, D16, and D17 in opposite directions. Specifically, one end of D15 forms the first end of the inductive current freewheeling branch, the other end of D15 is connected to D16, the other end of D16 is connected to D17, the other end of D17 is connected to D18, and the other end of D18 forms the second end of the inductive current freewheeling branch; the first and second ends of the inductive current freewheeling branch are respectively connected to... Figure 5 The corresponding protection node connections are shown.

[0029] During the main pulse discharge phase, the inductive current freewheeling branch does not bear the main pulse current output from the energy storage capacitor 5 to the electromagnetic pulse load 7. When the IGBT power switch module 6 is turned off, the current in the electromagnetic pulse load 7 cannot change abruptly. When the voltage across its terminals reaches the operating condition, the inductive current freewheeling branch forms an inductive current release path, allowing the remaining inductive energy in the electromagnetic pulse load 7 to be released gradually.

[0030] D11 to D18 employ high-voltage diodes suitable for high-voltage pulse circuits. The reverse repetitive peak voltage of each high-voltage diode is determined based on the maximum reverse voltage it withstands in the corresponding branch, and the non-repetitive peak forward current of each high-voltage diode is not less than the maximum transient current that may flow through the corresponding branch. The specific models of D11 to D18 can be selected based on the maximum charging voltage of the energy storage capacitor 5, the equivalent inductance of the electromagnetic pulse load 7, the pulse peak current, and the rated withstand voltage of the IGBT power switch module 6.

[0031] The RC absorption circuit includes an absorption resistor and an absorption capacitor connected in series, and is connected in parallel with the IGBT power switching module or electromagnetic pulse load. It is used to absorb transient energy generated during power switching and reduce voltage spikes, voltage oscillations and overshoot in the pulse discharge circuit.

[0032] In one specific embodiment, the absorption resistor is R22 with a resistance of 100Ω; the absorption capacitor is C19 with a capacitance of 100nF. R22 and C19 are connected in series to form an RC absorption circuit.

[0033] The gate protection unit is connected to the gate drive circuit of the IGBT power switch module to limit the overvoltage between the IGBT gate and the emitter, and to keep the IGBT power switch module in the off state when the transistor current enhancement unit does not output the gate drive signal.

[0034] In one embodiment, the gate protection unit includes a gate discharge resistor and a transient voltage suppression device connected between the gate terminal and the emitter terminal of the IGBT power switching module. The gate discharge resistor is used to release residual gate charge, and the transient voltage suppression device is used to limit forward and reverse overvoltages between the gate terminal and the emitter terminal.

[0035] The residual charge discharge unit is connected in parallel across the electromagnetic pulse load to release the residual charge across the electromagnetic pulse load after the pulse discharge ends or the circuit stops working. In one specific embodiment, the residual charge discharge unit includes a discharge resistor R2 with a resistance of 3MΩ.

[0036] The fault detection and fast shutdown unit is connected to the IGBT power switch module, the optocoupler isolation drive unit and the control unit respectively. It is used to detect abnormal states of the IGBT power switch module or the pulse discharge circuit, and block the gate drive signal output by the transistor current enhancement unit to the IGBT power switch module when an abnormal state is detected.

[0037] In one embodiment, the fault detection and rapid shutdown unit includes a fault detection circuit, a hardware drive blocking circuit, and a fault feedback circuit. The fault detection circuit is connected to at least one of the main current terminal, the gate drive circuit, and the pulse discharge circuit of the IGBT power switching module, and is used to detect at least one of overcurrent, overvoltage, or drive abnormality.

[0038] The hardware-driven blocking circuit is connected between the fault detection circuit and the transistor current enhancement unit. When the fault detection circuit outputs a fault signal, the hardware-driven blocking circuit blocks the output of the transistor current enhancement unit, causing the IGBT power switching module to turn off quickly.

[0039] The fault feedback circuit sends a fault signal to the control unit. Based on the fault signal, the control unit stops the external charging power supply from charging the energy storage capacitor, prohibits the reception of new low-voltage trigger signals, and latches the corresponding fault state. The control unit maintains the prohibited charging and prohibited triggering states until the fault state is cleared and the fault reset is completed.

[0040] The present invention also provides a control method for an isolated-triggered kilovolt-level high-energy pulse discharge circuit, comprising the following steps: The IGBT power switch module is kept off, and the energy storage capacitor is charged by an external charging power supply. Detect the charging status of the energy storage capacitor and the fault status of the pulse discharge circuit. When the energy storage capacitor reaches the preset charging voltage, no fault is detected, and a valid low-voltage trigger signal is received, the low-voltage trigger signal is sequentially photoelectrically isolated, current amplified, and waveform shaped, and the processed trigger signal is used to drive the IGBT power switch module to conduct. The energy storage capacitor releases pulsed electrical energy to the electromagnetic pulse load through a pulse discharge circuit consisting of an IGBT power switching module and an electromagnetic pulse load. The diode clamping and freewheeling network and RC snubber circuit are used to suppress the overshoot voltage and voltage oscillation generated by the IGBT power switching module when it is turned on or off, and to release the remaining inductive energy in the electromagnetic pulse load after the IGBT power switching module is turned off. After a pulse discharge ends, the IGBT power switch module is kept off and the energy storage capacitor is recharged. When an abnormality is detected in the IGBT power switch module or the pulse discharge circuit, the gate drive signal of the IGBT power switch module is blocked, the charging of the energy storage capacitor is stopped, and triggering is prohibited again.

[0041] In one implementation, when a fault is detected, the hardware-driven blocking circuit first directly blocks the gate drive signal output by the transistor current enhancement unit to the IGBT power switching module; then the fault signal is sent to the control unit, which stops the external charging power supply and latches the fault state; then the residual charge at both ends of the electromagnetic pulse load is released through the residual charge discharge unit; before the fault state is cleared and the fault reset is completed, the charging and triggering prohibition states are maintained.

[0042] Compared with the prior art, the present invention has the following beneficial effects: This invention isolates the low-voltage control side from the kilovolt-level high-voltage power side by sequentially setting an optocoupler isolation drive unit and a transistor current enhancement unit between the low-voltage trigger input interface and the IGBT power switch module, thereby improving the charging and discharging capability of the IGBT gate, which helps to shorten the switching transition time of the IGBT, reduce switching losses, and improve the trigger anti-interference capability.

[0043] This invention constructs a pulse discharge circuit using an energy storage capacitor, an IGBT power switching module, and an electromagnetic pulse load, which can release the electrical energy in the energy storage capacitor to the electromagnetic pulse load in a short time. Using a 400μF, 1.2kV energy storage capacitor charged to 1000V, approximately 200J of single-pulse energy storage can be generated to meet the need for high-energy short pulses from the Boomer load.

[0044] This invention provides a release path for residual inductive current in electromagnetic pulse loads through the combination of diode clamping, freewheeling network and RC absorption circuit, and absorbs transient energy generated during IGBT turn-on and turn-off. This helps to suppress voltage spikes, voltage oscillations and overshoot in the pulse discharge circuit, and reduces the risk of IGBT power switching modules being subjected to overvoltage surges.

[0045] This invention protects the IGBT gate drive circuit by using a gate discharge resistor and a transient voltage suppression device, which can release residual charge on the gate, limit transient overvoltage between the gate and the emitter, and reduce the risk of IGBT mis-turn-on and gate damage.

[0046] This invention releases residual charge at both ends of the electromagnetic pulse load through a residual charge discharge unit, which can reduce the safety risks caused by high voltage residue during circuit shutdown or maintenance.

[0047] This invention directly blocks the IGBT gate drive signal when an overcurrent, overvoltage, or drive abnormality is detected by the fault detection and rapid shutdown unit. The control unit stops the charging of the energy storage capacitor, prohibits re-triggering, and latches the fault state. This can prevent continued charging or repeated discharging under fault conditions, and improve the safety and operational reliability of the kilovolt-level high-energy pulse discharge circuit. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the structure of an isolated-triggered kilovolt-level high-energy pulse discharge circuit system according to the present invention; Figure 2 This is a schematic diagram of the control method for a kilovolt-level high-energy pulse discharge circuit with isolation triggering according to the present invention; Figure 3 This is a schematic diagram of the low-voltage trigger signal isolation drive circuit structure of the present invention; Figure 4 This is a schematic diagram of the gate drive and protection circuit structure of the IGBT power switch module of the present invention; Figure 5 This is a schematic diagram of the main circuit and composite protection network structure for energy storage pulse discharge of the present invention; Figure 6 This is a schematic diagram of the fault detection and rapid shutdown circuit structure of the present invention; Figure 7 This is a schematic diagram of the physical separation structure of the charging circuit and the partial pulse discharge circuit of the present invention. Detailed Implementation

[0049] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The following embodiments are used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention.

[0050] Example 1

[0051] This embodiment provides an isolated-triggered kilovolt-level high-energy pulse discharge circuit. The input terminal of the low-voltage trigger input interface 1 is used to receive the TRIG low-voltage trigger signal output from an external device, and the output terminal of the low-voltage trigger input interface 1 is connected to the trigger input terminal of the control unit 2. The drive control output terminal of the control unit 2 is connected to the input terminal of the optocoupler isolation drive unit 3, the output terminal of the optocoupler isolation drive unit 3 is connected to the input terminal of the transistor current enhancement unit 4, and the output terminal of the transistor current enhancement unit 4 is connected to the gate drive terminal of the IGBT power switch module 6.

[0052] The positive output terminal of the external charging power supply 10 is connected to the DC positive bus, and the negative output terminal of the external charging power supply 10 is connected to the DC negative bus. The energy storage capacitor 5 is connected between the DC positive bus and the DC negative bus. The external charging power supply 10 is used to charge the energy storage capacitor 5.

[0053] The IGBT power switch module 6 is connected in the pulse discharge circuit formed by the energy storage capacitor 5 and the electromagnetic pulse load 7. When the IGBT power switch module 6 is turned on, the energy storage capacitor 5 releases pulse energy to the electromagnetic pulse load 7 through the IGBT power switch module 6; when the IGBT power switch module 6 is turned off, the main pulse current path between the energy storage capacitor 5 and the electromagnetic pulse load 7 is cut off.

[0054] The diode clamping and freewheeling network 81 and the RC snubber circuit 82 are respectively connected to at least one of the IGBT power switching module 6 and the electromagnetic pulse load 7. The gate protection unit 83 is connected between the gate drive terminal and the corresponding emitter terminal of the IGBT power switching module 6. The residual charge discharge unit 84 is connected in parallel across the electromagnetic pulse load 7.

[0055] The fault detection circuit 91 is connected to the pulse discharge circuit, the IGBT power switch module 6, and its gate drive circuit, respectively. The fault output terminal of the fault detection circuit 91 is connected to the hardware drive blocking circuit 92 and the fault feedback circuit 93, respectively. The hardware drive blocking circuit 92 is connected to the output terminal of the transistor current enhancement unit 4, and the fault feedback circuit 93 is connected to the fault input terminal of the control unit 2.

[0056] The control unit 2 also has a charging control output terminal, which is connected to the enable terminal of the external charging power supply 10 to control the external charging power supply 10 to start or stop.

[0057] The low-voltage trigger input interface 1 includes a trigger signal input terminal, an input current limiting resistor, an input filter capacitor, a level shaping circuit, and a trigger status indicator circuit.

[0058] The trigger signal input can be a BNC interface, terminal block, or aviation connector. The trigger signal input is connected to the input of the level shaping circuit via an input current limiting resistor. The input filter capacitor is connected between the input of the level shaping circuit and the low-voltage side reference ground. The output of the level shaping circuit is connected to the trigger input of control unit 2.

[0059] The trigger status indicator circuit includes a light-emitting diode (LED) and an indicator current-limiting resistor connected in series with the LED. The trigger status indicator circuit is connected to the trigger signal input terminal or the output terminal of the level shaping circuit to display the input status of the TRIG low-voltage trigger signal.

[0060] In one possible implementation, the high-level voltage of the TRIG low-voltage trigger signal is 3.3–12V, and the trigger pulse width is 50μs–5ms; the resistance of the input current-limiting resistor is 1–10kΩ, and the capacitance of the input filter capacitor is 1–100nF. The level shaping circuit uses a Schmitt trigger or a comparator to reduce the possibility of repeated triggering caused by input signal edge jitter.

[0061] After receiving the TRIG low-voltage trigger signal, control unit 2 does not immediately output the gate drive signal. Instead, it first determines whether the energy storage capacitor 5 has reached the preset charging state and whether the circuit is in a fault-free state. Only when the trigger conditions are met does control unit 2 output the drive control signal to the optocoupler isolation drive unit 3.

[0062] The optocoupler isolation drive unit 3 includes an optocoupler driver U7, an input-side power supply circuit, an output-side isolation power supply circuit, and an output signal conditioning circuit.

[0063] The positive input terminal of the optocoupler driver U7 is connected to the drive control output terminal of the control unit 2 via an input current-limiting resistor, and the negative input terminal of the optocoupler driver U7 is connected to the low-voltage side reference ground. The output power supply terminal of the optocoupler driver U7 is connected to the output isolation power supply circuit, and the output reference terminal of the optocoupler driver U7 is connected to the auxiliary emitter corresponding to the IGBT power switch module 6.

[0064] The output-side isolated power supply circuit adopts an isolated DC-DC power module. Its input is connected to the low-voltage control power supply, and its output provides isolated drive power to the optocoupler driver U7 and the transistor current enhancement unit 4.

[0065] The drive output terminal of the optocoupler driver U7 is connected to the input terminal of the transistor current enhancement unit 4. The drive control signal output from the low-voltage control side is transmitted through the optocoupler driver U7 and forms a drive signal that is electrically isolated from the low-voltage control side on the high-voltage power side.

[0066] In one possible implementation, the input-output isolation withstand voltage of the optocoupler driver U7 is not less than 2.5kV, the output driving voltage is 12-18V, preferably 15V, and the signal propagation delay is not greater than 2μs.

[0067] The transistor current enhancement unit 4 includes a first driving transistor 41, a second driving transistor 42, a gate charging branch 43, and a gate discharging branch 44.

[0068] The first driving transistor 41 and the second driving transistor 42 are complementary transistors and form a push-pull driving circuit. The first driving transistor 41 is used to provide charging current to the gate of the IGBT power switching module 6, and the second driving transistor 42 is used to provide discharging current to the gate of the IGBT power switching module 6.

[0069] The control terminals of the first driving transistor 41 and the second driving transistor 42 are respectively connected to the driving output terminal of the optocoupler driver U7, and their output nodes form a push-pull driving output terminal. The push-pull driving output terminal is connected to the gate of the IGBT power switch module 6 through the gate charging branch 43 and the gate discharging branch 44, respectively.

[0070] The gate charging branch 43 includes a first unidirectional conducting device and a first gate driving resistor, and the gate discharging branch 44 includes a second unidirectional conducting device and a second gate driving resistor. The first unidirectional conducting device and the second unidirectional conducting device have opposite conduction directions, so that the gate charging current and the gate discharging current flow through different resistor branches respectively.

[0071] In one possible implementation, the first gate drive resistor has a resistance of 3.3–15 Ω, and the second gate drive resistor has a resistance of 1–10 Ω. The second gate drive resistor can be smaller than the first gate drive resistor to improve the gate charge release speed while maintaining the normal turn-on speed of the IGBT.

[0072] When the optocoupler driver U7 outputs a turn-on signal, the first driving transistor 41 turns on, and the driving current flows into the IGBT gate through the gate charging branch 43, turning on the IGBT power switch module 6. When the optocoupler driver U7 outputs a turn-off signal, the second driving transistor 42 turns on, and the IGBT gate charge is released to the auxiliary emitter through the gate discharge branch 44, turning off the IGBT power switch module 6.

[0073] The energy storage capacitor 5 is C1, with its positive terminal connected to the DC positive bus and its negative terminal connected to the DC negative bus. The positive output terminal of the external charging power supply 10 is connected to the positive terminal of the energy storage capacitor 5 via a charging conductor, and the negative output terminal of the external charging power supply 10 is connected to the negative terminal of the energy storage capacitor 5 via a return conductor.

[0074] Preferably, a high-voltage blocking diode is provided between the positive output terminal of the external charging power supply 10 and the energy storage capacitor 5, and the conduction direction of the high-voltage blocking diode is from the external charging power supply 10 to the energy storage capacitor 5. The high-voltage blocking diode conducts in the forward direction during charging and is reverse-biased when the energy storage capacitor 5 discharges to the electromagnetic pulse load 7, so as to prevent the peak pulse current from entering the external charging power supply 10 and the charging cable in the reverse direction.

[0075] In this embodiment, the energy storage capacitor 5 has a capacitance of 400μF, a rated withstand voltage of 1.2kV, and a target charging voltage of 1000V. When the energy storage capacitor 5 is charged to 1000V, its stored energy is: E=1 / 2CU²=1 / 2×400×10^-6×1000²=200J.

[0076] The energy storage capacitor 5 is also connected to an energy storage voltage detection branch. This branch includes a high-impedance voltage divider network, a filter circuit, and an isolation sampling circuit; its output is connected to the analog input of the control unit 2. The control unit 2 determines whether the energy storage capacitor 5 has reached the preset charging voltage based on the output of the energy storage voltage detection branch.

[0077] The IGBT power switch module 6 includes a first IGBT 61, a second IGBT 63, a first freewheeling diode 62 connected in antiparallel to the first IGBT 61, and a second freewheeling diode 64 connected in antiparallel to the second IGBT 63.

[0078] The main current paths of the first IGBT 61 and the second IGBT 63 are connected in series between the DC positive bus and the DC negative bus, and the connection node of the first IGBT 61 and the second IGBT 63 forms the midpoint M of the half bridge.

[0079] In this embodiment, the first terminal of the electromagnetic pulse load 7 is connected to the positive DC bus, and the second terminal of the electromagnetic pulse load 7 is connected to the midpoint M of the half-bridge. The collector of the second IGBT 63 is connected to the midpoint M of the half-bridge, and the emitter of the second IGBT 63 is connected to the negative DC bus. The output terminal of the transistor current enhancement unit 4 is connected to the gate of the second IGBT 63, and the output reference terminal of the optocoupler isolation drive unit 3 is connected to the auxiliary emitter of the second IGBT 63.

[0080] The gate of the first IGBT 61 is connected to the auxiliary emitter of the first IGBT 61 through a gate discharge resistor, so that the first IGBT 61 remains off during the main pulse discharge in this embodiment. The first freewheeling diode 62 is used to provide a freewheeling path for the residual inductive current in the electromagnetic pulse load 7 after the second IGBT 63 is turned off.

[0081] When the second IGBT 63 is turned on, the main pulse current flows out from the positive terminal of the energy storage capacitor 5, and flows sequentially through the DC positive bus, the electromagnetic pulse load 7, the midpoint of the half bridge M, and the second IGBT 63 to the DC negative bus, and then returns to the negative terminal of the energy storage capacitor 5.

[0082] After the second IGBT 63 is turned off, the inductive current in the electromagnetic pulse load 7 cannot change abruptly. The remaining inductive current flows from the midpoint M of the half-bridge through the first freewheeling diode 62 back to the DC positive bus and forms a freewheeling circuit through the electromagnetic pulse load 7.

[0083] In another embodiment, the electromagnetic pulse load 7 can be connected between the midpoint M of the half-bridge and the DC negative bus, and the main pulse discharge is controlled by the first IGBT 61, while the second freewheeling diode 64 provides the freewheeling path.

[0084] The energy storage capacitor 5, the IGBT power switching module 6, and the electromagnetic pulse load 7 are arranged adjacent to each other and form a partial pulse discharge circuit through copper busbars, copper strips, laminated busbars, or rigid conductive connectors. The partial pulse discharge circuit does not include the long-distance charging cable connecting to the external charging power supply 10.

[0085] In one possible implementation, the copper busbar has a width of 20-50 mm and a thickness of 1-3 mm, the conductive path length from the energy storage capacitor 5 to the IGBT power switch module 6 is no more than 300 mm, and the conductive path length from the IGBT power switch module 6 to the electromagnetic pulse load 7 is no more than 500 mm.

[0086] The diode clamping and freewheeling network 81 includes high-voltage diodes D11 to D18. Specifically, D11 to D14 are configured according to... Figure 5 The polarity and connection relationships shown constitute a voltage clamping branch, used to form a voltage release path when a transient overvoltage occurs in the pulse discharge circuit; D15~D18 according to Figure 5 The polarity and connection relationship shown constitute the inductive current freewheeling branch, which is used to provide a release path for the remaining inductive current in the electromagnetic pulse load 7 after the IGBT power switch module 6 is turned off.

[0087] The voltage clamping branch remains off when the voltage across the IGBT power switch module 6 is lower than its operating voltage; when the overshoot voltage generated by the IGBT turning on or off reaches the operating voltage, the voltage clamping branch turns on to provide a release path for transient current.

[0088] The inductive current freewheeling branch remains off or does not bear the main pulse current during the main pulse discharge phase; when the IGBT power switch module 6 is turned off, the inductive current freewheeling branch provides a release path for the remaining inductive current in the electromagnetic pulse load 7.

[0089] The RC snubber circuit 82 includes a snubber resistor R22 and a snubber capacitor C19. The snubber resistor R22 and the snubber capacitor C19 are connected in series, and the series RC snubber branch is connected across the main current terminals of the IGBT power switch module 6, or across the midpoint M of the half-bridge and the corresponding DC bus.

[0090] In this embodiment, the resistance of the absorption resistor R22 is 100Ω, the capacitance of the absorption capacitor C19 is 100nF, and the rated withstand voltage is not less than 1.2kV, preferably not less than 1.5kV.

[0091] When the IGBT power switch module 6 is turned on or off and generates a high-frequency transient voltage, the absorption capacitor C19 provides a bypass for the high-frequency current, and the absorption resistor R22 consumes the transient energy received by the absorption capacitor C19 and suppresses the continuous oscillation between the absorption capacitor C19 and the parasitic inductance of the circuit.

[0092] The RC snubber circuit 82 is located near the IGBT power switch module 6, and the length of the connecting conductor between R22 and C19 and the IGBT power switch module 6 is preferably no more than 100mm.

[0093] The gate protection unit 83 includes a gate discharge resistor and a transient voltage suppression device. The gate discharge resistor and the transient voltage suppression device are respectively connected between the IGBT gate and the corresponding auxiliary emitter.

[0094] In one possible implementation, the gate discharge resistor has a resistance of 5 to 20 kΩ, and the transient voltage suppression device is a bidirectional TVS device with a clamping voltage of 16 to 20 V.

[0095] When the optocoupler isolation drive unit 3 and the transistor current enhancement unit 4 do not output drive signals, the gate discharge resistor releases the IGBT gate charge to the auxiliary emitter, keeping the IGBT off. Transient voltage suppression devices are used to limit forward and reverse overvoltages between the gate and the auxiliary emitter.

[0096] The residual charge discharge unit 84 includes a discharge resistor R2, which is connected in parallel between the first and second terminals of the electromagnetic pulse load 7.

[0097] In this embodiment, the resistance of the bleeder resistor R2 is 3MΩ. The bleeder resistor R2 can be composed of multiple high-voltage resistors connected in series to share the operating voltage.

[0098] After the pulse discharge is completed, the parasitic capacitance in the electromagnetic pulse load 7, the connecting conductor, and the transmitting component may retain a small amount of residual charge, which is gradually released through the discharge resistor R2. Since the resistance of the discharge resistor R2 is much larger than the pulse operating impedance of the electromagnetic pulse load 7, its shunting effect during normal pulse discharge is small.

[0099] The fault detection circuit 91 includes at least one of the following: a pulse overcurrent detection branch, a bus overvoltage detection branch, and a drive voltage abnormality detection branch.

[0100] The pulse overcurrent detection branch is set in the partial pulse discharge circuit, and it can be a Rogowski coil, a current transformer, or a broadband Hall current sensor. The output of the pulse overcurrent detection branch is connected to a high-speed comparator via a signal conditioning circuit.

[0101] The bus overvoltage detection branch is connected between the DC positive bus and the DC negative bus, and includes a high-resistance voltage divider circuit and an overvoltage comparator. The drive voltage abnormality detection branch is connected to the output-side isolated power supply circuit of the optocoupler isolated drive unit 3.

[0102] The outputs of each fault detection branch are connected to the hardware drive blocking circuit 92 via a logic OR circuit. The hardware drive blocking circuit 92 includes a turn-off transistor, the main current path of which is connected between the output of the transistor current enhancement unit 4 and the auxiliary emitter of the IGBT.

[0103] When any fault detection branch outputs a valid fault signal, the turn-off transistor is turned on, bypassing the IGBT gate drive signal to the auxiliary emitter, thus turning off the IGBT power switch module 6. This hardware turn-off process does not rely on the control unit 2 to complete the software calculation.

[0104] The fault feedback circuit 93 uses an optocoupler or digital isolator, with its input connected to the fault detection circuit 91 and its output connected to the fault input of the control unit 2.

[0105] Upon receiving a fault signal, control unit 2 stops outputting drive control signals to optocoupler isolation drive unit 3, shuts off external charging power supply 10 via charging control output, and latches the fault state. Control unit 2 does not respond to new TRIG low-voltage trigger signals until the fault state is cleared and fault reset is completed.

[0106] After the circuit is started, the control unit 2 first keeps the IGBT power switch module 6 off and controls the external charging power supply 10 to charge the energy storage capacitor 5.

[0107] The charging current output from the external charging power supply 10 flows into the energy storage capacitor 5, causing the voltage across the energy storage capacitor 5 to gradually increase. The control unit 2 obtains the voltage of the energy storage capacitor 5 in real time through the energy storage voltage detection branch.

[0108] When the energy storage capacitor 5 reaches the preset charging voltage, the fault detection and fast shutdown unit 9 does not output a fault signal, and the low-voltage trigger input interface 1 receives a valid TRIG signal, the control unit 2 outputs a drive control signal to the optocoupler isolation drive unit 3.

[0109] The drive control signal is electrically isolated between the low-voltage control side and the high-voltage power side by the optocoupler driver U7, and then amplified and shaped by the transistor current enhancement unit 4 before being applied to the gate of the IGBT power switch module 6.

[0110] After the IGBT power switch module 6 is turned on, the energy storage capacitor 5 rapidly releases pulsed electrical energy to the electromagnetic pulse load 7 through a partial pulse discharge circuit. The pulsed current in the electromagnetic pulse load 7 generates a rapidly changing pulsed magnetic field, which is used to drive the Boomer transmitter component to generate acoustic pulses.

[0111] During discharge, the diode clamping and freewheeling network 81 limits the overshoot voltage across the IGBT power switching module 6, the RC snubber circuit 82 absorbs high-frequency transient energy, and the gate protection unit 83 limits the gate transient overvoltage.

[0112] After a pulse discharge is completed, control unit 2 cancels the drive control signal, transistor current enhancement unit 4 releases the IGBT gate charge, and IGBT power switch module 6 is turned off. The remaining inductive current in electromagnetic pulse load 7 is released through diode clamping and freewheeling network 81.

[0113] When an overcurrent, overvoltage, or drive abnormality is detected, the hardware drive blocking circuit 92 directly blocks the gate drive signal; the control unit 2 then stops the external charging power supply 10, prevents re-triggering, and latches the fault state.

[0114] Example 2

[0115] This embodiment provides a control method for an isolated-triggered kilovolt-level high-energy pulse discharge circuit, implemented using the circuit described in Embodiment 1, and specifically includes the following steps.

[0116] S1, Control circuit power-on and initial shutdown After the low-voltage control power supply is turned on, the control unit 2 sets the drive control output terminal to an invalid level, so that the optocoupler isolation drive unit 3 and the transistor current enhancement unit 4 do not output gate drive signals.

[0117] The gate discharge resistor in the gate protection unit 83 keeps the IGBT gate at the auxiliary emitter potential, thus keeping the IGBT power switch module 6 off.

[0118] The control unit 2 simultaneously sets the enable terminal of the external charging power supply 10 to the stop state to prevent charging of the energy storage capacitor 5 before the system status is confirmed.

[0119] S2, Perform power-on self-test The control unit 2 sequentially detects the initial voltage of the energy storage capacitor 5, the output power supply voltage of the optocoupler isolation drive unit 3, the output status of the fault detection circuit 91, and the static status of the low-voltage trigger input interface 1.

[0120] When the initial voltage of the energy storage capacitor 5 is higher than the preset safe voltage, the control unit 2 keeps the external charging power supply 10 off and maintains the state of prohibiting charging and prohibiting triggering until the energy storage voltage detection branch detects that the voltage of the energy storage capacitor 5 has dropped below the preset safe voltage.

[0121] In one embodiment, the safety voltage is 50V. The control unit 2 determines that the power-on self-test has passed only when the voltage of the energy storage capacitor 5 is not higher than 50V, the output-side drive voltage is within a preset range, the fault detection circuit 91 does not output a fault signal, and there is no continuously effective trigger level at the trigger input terminal.

[0122] When any self-test item fails to meet the requirements, the control unit 2 enters a fault state, prohibits charging and triggering, and outputs corresponding fault information.

[0123] S3, Set charging and trigger parameters After the power-on self-test passes, the control unit 2 obtains the preset charging voltage, the allowable trigger voltage range, the trigger pulse width, the minimum trigger time interval, the overvoltage threshold, and the overcurrent threshold.

[0124] In this embodiment, the preset charging voltage is 1000V, the allowable trigger voltage range is 980-1020V, the energy storage overvoltage threshold is 1050V, the IGBT gate control pulse width is 0.2-1.5ms, preferably 0.6ms, and the minimum trigger time interval is 0.5-2s.

[0125] The above parameters can be pre-stored in the control unit 2, or they can be set by an external host computer or human-computer interaction device.

[0126] S4, Control the charging of the energy storage capacitor After confirming that the circuit is in a fault-free state, the control unit 2 outputs a start signal to the enable terminal of the external charging power supply 10.

[0127] The external charging power supply 10 outputs charging current to the energy storage capacitor 5, and the voltage of the energy storage capacitor 5 gradually increases. During the charging process, the control unit 2 keeps the IGBT power switch module 6 off.

[0128] The control unit 2 collects the real-time voltage of the energy storage capacitor 5 according to a preset sampling period. In one embodiment, the sampling period is 1 to 10 ms.

[0129] When the real-time voltage of the energy storage capacitor 5 is lower than the allowable trigger voltage range, the control unit 2 continues charging; when the real-time voltage enters the allowable trigger voltage range, the control unit 2 reduces or stops the charging current; when the real-time voltage exceeds the energy storage overvoltage threshold, the control unit 2 immediately stops the external charging power supply 10 and enters the energy storage overvoltage fault state.

[0130] S5. Determine energy storage completion and generate trigger permission. When the real-time voltage of the energy storage capacitor 5 enters the allowable trigger voltage range and remains stable for a preset time, the control unit 2 determines that energy storage is complete.

[0131] In this embodiment, the stabilization time is 10-100ms, preferably 20ms.

[0132] Control unit 2 further confirms that the fault detection circuit 91 does not output a fault signal, the output side power supply voltage of the optocoupler isolation drive unit 3 is normal, and the minimum trigger time interval has been exceeded since the last pulse discharge.

[0133] When all the above conditions are met, the control unit 2 generates a trigger permission state; when any condition is not met, the control unit 2 remains in a trigger prohibition state.

[0134] S6. Receive and verify the low-voltage trigger signal. The low-voltage trigger input interface 1 receives the external TRIG low-voltage trigger signal, and after input current limiting, filtering and level shaping, transmits the trigger signal to the control unit 2.

[0135] Control unit 2 detects the level, duration, and input edge of the trigger signal. Control unit 2 only determines the trigger signal as valid when the level and pulse width of the trigger signal are within a preset range and the system is in a trigger-enabled state.

[0136] If the trigger signal duration is too short, too long, the system fails to reach the preset charging voltage, or there is a circuit fault, the control unit 2 will reject the trigger and keep the IGBT power switch module 6 off.

[0137] S7, Output isolated drive signal After the control unit 2 confirms that the trigger signal is valid, it temporarily stops or prohibits the external charging power supply 10 from continuing to output, and outputs a drive control signal to the optocoupler isolation drive unit 3.

[0138] The drive control signal is transmitted to the high-voltage power side via the optocoupler driver U7, completing the electrical isolation between the low-voltage control side and the high-voltage power side.

[0139] The isolated drive signal output from the optocoupler driver U7 is input to the transistor current enhancement unit 4. The first drive transistor 41 provides charging current to the IGBT gate through the gate charging branch 43, causing the IGBT power switch module 6 to switch from the off state to the on state.

[0140] S8, Perform high-energy pulse discharge After the IGBT power switch module 6 is turned on, a pulse discharge circuit is formed between the energy storage capacitor 5 and the electromagnetic pulse load 7.

[0141] The pulse current in the energy storage capacitor 5 returns to the energy storage capacitor 5 through the electromagnetic pulse load 7 and the IGBT power switch module 6, thereby rapidly releasing the electrical energy in the energy storage capacitor 5 to the electromagnetic pulse load 7.

[0142] With a storage capacitor 5 of 400μF and a charging voltage of 1000V, the stored energy before a single discharge is 200J. The pulse current in the electromagnetic pulse load 7 is in the kiloampere range, and the duration of the main pulse is determined based on the load inductance and the circuit resistance.

[0143] During the discharge process, the control unit 2 does not accept new trigger signals to avoid repeated triggering during the same discharge period.

[0144] S9, Perform discharge process protection During the conduction of the IGBT power switch module 6, the fault detection circuit 91 continuously monitors the pulse current, bus voltage, and drive voltage.

[0145] The diode clamping and freewheeling network 81 limits the overshoot voltage in the pulse discharge circuit; the RC snubber circuit 82 absorbs high-frequency transient energy and suppresses voltage oscillation; and the gate protection unit 83 limits the transient voltage between the IGBT gate and the auxiliary emitter.

[0146] When the fault detection circuit 91 does not detect any abnormality, the control unit 2 maintains the IGBT power switch module 6 on according to the preset gate control pulse width.

[0147] When the fault detection circuit 91 detects pulse overcurrent, bus overvoltage, or drive abnormality, it directly enters the fault rapid shutdown process in step S12.

[0148] S10, Normal shutdown IGBT power switch module Once the preset gate control pulse width is reached, or the pulse current drops to the preset normal shutdown condition, the control unit 2 cancels the drive control signal.

[0149] The output state of the optocoupler driver U7 changes accordingly, and the second driving transistor 42 releases the IGBT gate charge through the gate discharge branch 44, causing the IGBT power switch module 6 to switch from the on state to the off state.

[0150] After the IGBT power switch module 6 is turned off, the remaining inductive current in the electromagnetic pulse load 7 forms a freewheeling path through the diode clamp and freewheeling network 81 and gradually decays.

[0151] The RC snubber circuit 82 absorbs the high-frequency transient energy during the turn-off process to reduce the turn-off overshoot voltage across the IGBT power switch module 6.

[0152] S11. Perform post-discharge detection and recharging. After the IGBT power switch module 6 is turned off, the control unit 2 collects the remaining voltage of the energy storage capacitor 5, the peak value of the pulse current, and the status of the fault detection circuit 91.

[0153] When no fault is detected and the pulse current has decayed to below the preset safe current, the control unit 2 releases the trigger lock.

[0154] Control unit 2 restarts external charging power supply 10, performs the next cycle charging of energy storage capacitor 5, and returns to step S4.

[0155] Before recharging, the residual charge discharge unit 84 continuously discharges the residual charge at both ends of the electromagnetic pulse load 7.

[0156] S12, Perform fault quick shutdown When the fault detection circuit 91 detects pulse overcurrent, bus overvoltage, or drive abnormality, the fault detection circuit 91 outputs a valid fault signal to the hardware drive blocking circuit 92.

[0157] The hardware-driven blocking circuit 92 directly blocks the drive signal output from the transistor current enhancement unit 4 to the IGBT gate, and releases the IGBT gate charge by turning off the transistor, thereby turning off the IGBT power switch module 6.

[0158] The hardware rapid shutdown does not wait for the control unit 2 to complete the software judgment. In one possible implementation, the response time from the output of the fault signal by the fault detection circuit 91 to the start of the drop in the IGBT gate voltage is no more than 10μs, preferably no more than 5μs.

[0159] S13, Stop charging and latch fault. The fault feedback circuit 93 transmits the fault signal to the control unit 2.

[0160] After receiving the fault signal, the control unit 2 stops outputting drive control signals to the optocoupler isolation drive unit 3 and controls the external charging power supply 10 to stop charging the energy storage capacitor 5.

[0161] Control unit 2 records the fault type, fault occurrence time, energy storage voltage and pulse current at the time of fault occurrence, and latches the fault status.

[0162] In the fault latching state, the control unit 2 does not respond to the new TRIG low voltage trigger signal and keeps the IGBT power switch module 6 in the off state.

[0163] S14. Release residual charge and perform fault reset. After confirming that the IGBT power switch module 6 has been turned off, the residual charge discharge unit 84 releases the residual charge at both ends of the electromagnetic pulse load 7.

[0164] After the cause of the fault is eliminated, the operator sends a reset request to the control unit 2 via the manual reset button or the remote reset command.

[0165] Control unit 2 re-detects the voltage of energy storage capacitor 5, the output drive voltage, and the status of fault detection circuit 91. Only when the voltage of energy storage capacitor 5 is within the allowable range, the drive voltage is normal, and the fault signal has disappeared, does control unit 2 release the fault latch and return to step S2 to perform power-on self-test.

[0166] Example 3

[0167] This embodiment illustrates the application of the isolated-triggered kilovolt-level high-energy pulse discharge circuit in a low-voltage pulse humming seismic detection device.

[0168] The deck side is equipped with an AC-DC high-voltage capacitor charging power supply, a deck controller, a display screen, and an external trigger interface; the underwater side is equipped with a sealed electronic compartment and a Boomer transmitter unit. The isolated triggering kilovolt-level high-energy pulse discharge circuit is located inside the sealed electronic compartment, with the energy storage capacitor 5, IGBT power switch module 6, and electromagnetic pulse load 7 arranged adjacent to each other.

[0169] The deck side and the underwater side are connected by a composite cable with a length of 10 to 50 meters. In this embodiment, the composite cable is 25 meters long. The composite cable includes a DC charging conductor, a control and communication conductor, and a trigger signal conductor.

[0170] The deck-side AC-DC high-voltage capacitor charging power supply has an output voltage of 1000V and a rated output power of 1.5kW. This charging power supply charges the 400μF energy storage capacitor 5 on the underwater side via a composite cable. The energy storage capacitor 5, the IGBT power switch module 6, and the Boomer transmitting coil form a localized pulse discharge circuit within the sealed electronics compartment and its adjacent transmitting unit.

[0171] Before the operation begins, the Boomer launcher unit is deployed to a position 5–50 m below the water surface. The deck controller controls the charging power supply to charge the energy storage capacitor 5. When the energy storage voltage reaches 980–1020V, the system enters the ready-to-trigger state.

[0172] The seismic data acquisition equipment outputs a TRIG signal to the low-voltage trigger input interface 1 at a repetition frequency of 0.2 to 2 Hz. In this embodiment, the trigger repetition frequency is 1 Hz. After being confirmed by the control unit 2, the TRIG signal passes sequentially through the optocoupler isolation drive unit 3 and the transistor current enhancement unit 4 to drive the IGBT power switch module 6 to conduct.

[0173] Approximately 200 J of electrical energy in the energy storage capacitor 5 is released to the Boomer transmitting coil in a short period of time. The kiloampere-level pulsed current in the transmitting coil generates a rapidly changing pulsed magnetic field. This pulsed magnetic field induces a current in a conductive vibrating plate positioned opposite the transmitting coil, forming a transient electromagnetic repulsion force that causes the vibrating plate to emit acoustic pulses toward the water.

[0174] Acoustic pulses propagate towards the seabed and are reflected at the interfaces of different strata. Hydrophones or other acoustic receivers receive the reflected signals and transmit them to seismic data acquisition equipment to obtain information about shallow seabed sedimentary structures.

[0175] During continuous operation, control unit 2 records the energy storage voltage, trigger time, peak pulse current, and fault status before each trigger. After a pulse discharge ends, IGBT power switch module 6 is turned off, the system recharges energy storage capacitor 5, and waits for the next trigger.

[0176] The sealed electronic compartment is also equipped with a water ingress detection module. The output terminal of the water ingress detection module is connected to the water ingress detection input terminal of the control unit 2. In one specific circuit, the water ingress detection input terminal corresponds to pin 24 of the main control chip.

[0177] The water ingress detection module includes two spaced-apart detection electrodes positioned in a low-lying, easily flooded area inside the sealed electronic compartment. The distance between the two detection electrodes is 1–3 mm. The control unit 2 periodically detects the resistance between the two detection electrodes.

[0178] In this embodiment, when the equivalent resistance between the two detection electrodes is less than 100kΩ and the water ingress judgment condition is met for three consecutive detection cycles, the control unit 2 determines that water has entered the sealed electronic compartment.

[0179] Upon detecting water ingress, control unit 2 immediately stops outputting drive control signals to optocoupler-isolated drive unit 3 and sends water ingress fault information to deck controller. Based on the water ingress fault information, deck controller stops outputting the AC-DC high-voltage capacitor charging power supply and displays alarm information on the screen.

[0180] The system employs a latching mechanism to store water ingress faults. Until the underwater equipment is recovered, its sealing status is checked, and manual reset is completed, the system remains in a state where charging and triggering are prohibited. This reduces the risk of high-voltage faults caused by continued charging or accidental discharge after water has entered the sealed electronics compartment.

[0181] The trigger voltage, pulse width, drive current, protection threshold, load inductance, cable length, and trigger repetition frequency given in this embodiment are all feasible parameter combinations suitable for a 400μF, 1000V, 200J Boomer pulse discharge circuit. In other applications, the above parameters can be adjusted according to the energy storage capacitor capacity, the withstand voltage and pulse current capability of the IGBT power switch module, the impedance of the electromagnetic pulse load, and the required pulse energy.

Claims

1. A kilovolt-level high-energy pulse discharge circuit with isolation triggering, characterized in that, It includes a low-voltage trigger input interface, a control unit, an optocoupler isolation drive unit, a transistor current enhancement unit, an energy storage capacitor, an IGBT power switch module, an electromagnetic pulse load, a composite protection network, and a fault detection and fast shutdown unit. The low-voltage trigger input interface, the control unit, the optocoupler isolation drive unit, the transistor current enhancement unit, and the IGBT power switch module are connected in sequence. The optocoupler isolation drive unit is used to electrically isolate the low-voltage trigger signal, and the transistor current enhancement unit is used to amplify the current and shape the waveform of the isolated trigger signal. The energy storage capacitor is connected between the DC positive bus and the DC negative bus. The IGBT power switch module is connected to the pulse discharge circuit formed by the energy storage capacitor and the electromagnetic pulse load. It is used to control the energy storage capacitor to release pulse energy to the electromagnetic pulse load according to the trigger signal after electrical isolation, current amplification and waveform shaping. The composite protection network includes a diode clamping and freewheeling network, an RC snubber circuit, a gate protection unit, and a residual charge discharge unit. The diode clamping and freewheeling network and the RC snubber circuit are respectively connected to at least one of the IGBT power switching module and the electromagnetic pulse load. The gate protection unit is connected to the gate drive circuit of the IGBT power switching module, and the residual charge discharge unit is connected in parallel across the electromagnetic pulse load. The fault detection and fast shutdown unit is connected to the IGBT power switch module, the optocoupler isolation drive unit, and the control unit, respectively. When an abnormality is detected in the IGBT power switch module or the pulse discharge circuit, the unit blocks the gate drive signal output by the transistor current enhancement unit to the IGBT power switch module and outputs a fault signal to the control unit. The control unit is used to prevent re-triggering based on the fault signal and to stop the external charging power supply from charging the energy storage capacitor.

2. The isolated-triggered kilovolt-level high-energy pulse discharge circuit according to claim 1, characterized in that, The low-voltage trigger input interface includes a trigger signal input terminal, an input current limiting resistor, an input filter capacitor, and a trigger status indicator circuit; The trigger signal input terminal is connected to the trigger input terminal of the control unit via the input current limiting resistor. The input filter capacitor is connected between the trigger input terminal of the control unit and the low-voltage side reference ground. The trigger status indicator circuit is connected to the trigger signal input terminal and is used to indicate the input status of the low-voltage trigger signal.

3. The isolated-triggered kilovolt-level high-energy pulse discharge circuit according to claim 1, characterized in that, The optocoupler isolation drive unit includes an optocoupler driver and a low-voltage side power supply circuit and an isolation side power supply circuit respectively disposed on the input side and the output side of the optocoupler driver; The input terminal of the optocoupler driver is connected to the control unit, and the output terminal of the optocoupler driver is connected to the transistor current enhancement unit, so as to electrically isolate the low-voltage control side where the control unit is located from the high-voltage power side where the IGBT power switch module is located.

4. The isolated-triggered kilovolt-level high-energy pulse discharge circuit according to claim 3, characterized in that, The transistor current enhancement unit includes a first driving transistor and a second driving transistor, and the first driving transistor and the second driving transistor constitute a push-pull driving circuit. The input terminal of the push-pull drive circuit is connected to the output terminal of the optocoupler driver, and the output terminal of the push-pull drive circuit is connected to the gate terminal of the IGBT power switch module via a gate drive resistor, which is used to improve the gate charging current and gate discharging current of the IGBT power switch module.

5. The isolated-triggered kilovolt-level high-energy pulse discharge circuit according to claim 4, characterized in that, The transistor current enhancement unit includes a gate charging branch and a gate discharging branch that are separate from each other. The gate charging branch and the gate discharging branch each include a unidirectional conducting device and a gate driving resistor. The gate driving resistor in the gate charging branch and the gate driving resistor in the gate discharging branch have different resistance values ​​to adjust the turn-on speed and turn-off speed of the IGBT power switching module, respectively.

6. The isolated-triggered kilovolt-level high-energy pulse discharge circuit according to claim 1, characterized in that, The IGBT power switch module includes a first IGBT, a second IGBT, and a first freewheeling diode and a second freewheeling diode connected in anti-parallel to the first IGBT and the second IGBT, respectively. The main current paths of the first IGBT and the second IGBT are connected in series between the DC positive bus and the DC negative bus. The connection node of the first IGBT and the second IGBT forms the midpoint of a half-bridge. One end of the electromagnetic pulse load is connected to the midpoint of the half-bridge, and the other end is connected to the DC positive bus or the DC negative bus. At least one of the first freewheeling diode and the second freewheeling diode constitutes part of the diode clamping and freewheeling network, which is used to provide a release path for the inductive current in the electromagnetic pulse load after the IGBT power switching module is turned off.

7. The isolated-triggered kilovolt-level high-energy pulse discharge circuit according to claim 1, characterized in that, The energy storage capacitor is a pulse energy storage capacitor or an energy storage capacitor group composed of multiple pulse energy storage capacitors connected in parallel. The equivalent capacitance of the energy storage capacitor is 250-600μF, the rated withstand voltage is not less than 1.2kV, the charging voltage is 700-1000V, and the single energy storage capacity is 60-300J. When the energy storage capacitor has an equivalent capacitance of 400μF, a rated withstand voltage of 1.2kV, and a charging voltage of 1000V, the energy stored in the energy storage capacitor is 200J.

8. The isolated-triggered kilovolt-level high-energy pulse discharge circuit according to claim 1, characterized in that, The diode clamping and freewheeling network includes multiple high-voltage diodes, which are connected in series and / or in parallel to form a voltage clamping branch and an inductive current freewheeling branch. The clamping voltage of the voltage clamping branch is higher than the maximum charging voltage of the energy storage capacitor and lower than the rated withstand voltage of the IGBT power switch module, so as to form a voltage release path when the IGBT power switch module generates an overshoot voltage when it is turned on or off.

9. The isolated-triggered kilovolt-level high-energy pulse discharge circuit according to claim 8, characterized in that, The diode clamping and freewheeling network includes D11 to D18 high-voltage diodes; The RC absorption circuit includes an absorption resistor R22 and an absorption capacitor C19 connected in series. The resistance of the absorption resistor R22 is 100Ω and the capacitance of the absorption capacitor C19 is 100nF. The RC absorption circuit is connected in parallel with the IGBT power switch module or the electromagnetic pulse load to absorb transient energy of the switch and suppress voltage spikes, voltage oscillations and overshoot.

10. A control method for an isolated-triggered kilovolt-level high-energy pulse discharge circuit, characterized in that, The kilovolt-level high-energy pulse discharge circuit with isolation triggering as described in any one of claims 1 to 9 comprises: 1) Control the IGBT power switching module to remain off, and charge the energy storage capacitor by an external charging power supply; 2) Detect the charging status of the energy storage capacitor and the fault status of the pulse discharge circuit; 3) When the energy storage capacitor reaches the preset charging voltage, no fault is detected, and a valid low-voltage trigger signal is received, the low-voltage trigger signal is sequentially photoelectrically isolated, current amplified, and waveform shaped, and the processed trigger signal is used to drive the IGBT power switch module to conduct. 4) The energy storage capacitor releases pulsed electrical energy to the electromagnetic pulse load through a pulse discharge circuit composed of the IGBT power switching module and the electromagnetic pulse load; 5) The diode clamping and freewheeling network and RC snubber circuit are used to suppress the overshoot voltage and voltage oscillation generated by the IGBT power switch module being turned on or off, and the remaining inductive energy in the electromagnetic pulse load is released after the IGBT power switch module is turned off. 6) After a pulse discharge ends, keep the IGBT power switch module off and recharge the energy storage capacitor; 7) When an abnormality is detected in the IGBT power switch module or the pulse discharge circuit, the gate drive signal of the IGBT power switch module is blocked, the charging of the energy storage capacitor is stopped, and triggering is prohibited again.

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