High-power low-residual-voltage short-wave strong electromagnetic pulse suppression circuit

Abstract

The invention relates to a high-power low-residual-voltage short-wave strong electromagnetic pulse suppression circuit which comprises an I-stage transient protection circuit, a first decoupling circuit, an II-stage transient protection circuit, a filter circuit, a second decoupling circuit and an III-stage transient protection circuit. When a radio station works normally, the insertion loss of the suppression circuit is very low, and high-efficiency transmission of short-wave signals is ensured; when strong electromagnetic pulse attacks such as thunder and lightning or nuclear power are encountered, the suppression circuit can discharge strong electromagnetic pulses, it is ensured that the voltage entering a receiver is within the safe voltage range of the receiver, and meanwhile normal transmission of short wave signals is ensured. The suppression circuit disclosed by the invention can be widely applied to each equipment short-wave radio station, and the strong electromagnetic environment viability and the anti-interference capability of the short-wave radio station can be greatly improved.

Description

Technical Field

[0001] The invention relates to a high-power low-residual-voltage short-wave strong electromagnetic pulse suppression circuit, which is applied to strong electromagnetic pulse protection of short-wave radio stations and belongs to the field of strong electromagnetic pulse protection. Background Art

[0002] Shortwave radio is an important equipment for wireless communication. The shortwave signal sent by the shortwave radio can achieve the goal of long-distance communication through multiple reflections between the ground and the ionosphere. The operating frequency of shortwave communication is generally 2MHz-30MHz, and the wavelength is 150m-10m. The greater the transmission power of the shortwave radio, the longer the communication distance. For communications over one thousand kilometers, the radio transmission power needs to be greater than 400W. With the demand for long-distance radio communication, there are more and more kW-level high-power shortwave radios. The main disadvantage of shortwave radio communication is that it is easily interfered by natural or man-made electromagnetic pulses. Among them, the energy of lightning electromagnetic pulses and nuclear electromagnetic pulses is concentrated in the shortwave working frequency band, which is the main threat source for shortwave radios. It is necessary to design a real-time protection circuit for strong electromagnetic pulses in the working state of the radio during high-power shortwave transmission. Summary of the invention

[0003] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and provide a high-power, low-residual-voltage short-wave strong electromagnetic pulse suppression circuit to ensure normal communication of the short-wave radio station when subjected to strong electromagnetic pulse interference, and to prevent the short-wave radio station from being threatened by strong electromagnetic pulses such as natural lightning strikes or nuclear electromagnetic pulses, which may cause communication interruption.

[0004] The technical solution of the present invention is:

[0005] A high-power, low-residual-voltage, short-wave, strong electromagnetic pulse suppression circuit, comprising: a level I transient protection circuit, a first decoupling circuit, a level II transient protection circuit, a filtering circuit, a second decoupling circuit, and a level III transient protection circuit;

[0006] The level I transient protection circuit is realized by connecting a gas discharge tube and a varistor in parallel, and is used to protect the low-frequency part of a lightning electromagnetic pulse or a nuclear electromagnetic pulse, and its output end is connected to a first decoupling circuit;

[0007] The first decoupling circuit is used for the response timing and current shunting control of the first-level transient protection circuit and the second-level transient protection circuit, and the output end is connected to the second-level transient protection circuit;

[0008] The level II transient protection circuit is a voltage clamp circuit composed of a low-capacitance diode and a bidirectional TVS tube, which is used to further protect the residual energy of the level I transient protection circuit. Its output end is connected to the filter circuit;

[0009] The filter circuit is a high-pass filter composed of LC. The filter circuit ensures low insertion loss transmission of short-wave signals. It is also used to filter out residual low-frequency interference from the previous two-stage transient protection circuits. The output of the filter circuit is connected to the second decoupling circuit.

[0010] The second decoupling circuit is used for the response timing and current shunting control of the level II transient protection circuit and the level III transient protection circuit, and the output end is connected to the level III transient protection circuit;

[0011] The Level III transient protection circuit is a fast-response clamping circuit composed of a low-capacitance diode and a bidirectional TVS tube. It is used to protect the high-frequency part of nuclear power electromagnetic pulses and clamp the residual voltage at a lower level.

[0012] Furthermore, the level I transient protection circuit includes a gas discharge tube G1 and four parallel varistors VR1-VR4, wherein one end of the gas discharge tube G1 is connected to the signal terminal SIG, and the other end is grounded through the parallel varistors VR1-VR4.

[0013] Furthermore, the first decoupling circuit includes resistors R1 and R2 connected in parallel, one end of which is connected to the signal terminal SIG, and the other end of which is connected to the level II transient protection circuit as an output end of the first decoupling circuit.

[0014] Furthermore, the class II transient protection circuit includes low capacitance diodes D1 to D4 and 8 bidirectional TVS tubes V1 to V8, wherein in the D1 to D2 branches, D1 and D2 are connected in series, the cathode of the diode D1 is connected to the output end of the first decoupling circuit, the bidirectional TVS tubes are polarity-independent, V1 and V2 are connected in series, V3 and V4 are connected in series, V1 and V3 are connected to the anode of the diode D2, and V2 and V4 are connected to GND;

[0015] In the D3-D4 branch, D3 and D4 are connected in series, the anode of diode D3 is connected to the cathode of diode D1, the TVS tube has no polarity, V5 and V6 are connected in series, V7 and V8 are connected in series, V5 and V7 are connected to the cathode of diode D4, and V6 and V8 are connected to GND.

[0016] The bidirectional TVS tubes V1 to V8 are bidirectional transient suppression diodes.

[0017] Furthermore, the filtering circuit includes inductors L1~L2 and capacitors C1~C2, forming a 4th-order high-pass filtering circuit, wherein C1 and C2 are connected in series, one end of which is connected to the anode of D3 in the level II transient protection circuit, and the other end is connected to the resistor R3 of the second decoupling circuit, one end of L1 is connected between C1 and C2, and the other end is connected to GND, and one end of L2 is connected between C2 and the resistor R3, and the other end is connected to GND.

[0018] Furthermore, the second decoupling circuit includes a resistor R3, one end of which is connected to C3 in the filter circuit, and the other end of which is connected to the level III transient protection circuit.

[0019] Furthermore, the III-level transient protection circuit includes low-capacitance diodes D5-D8 and eight bidirectional TVS tubes V9-V16, and the bidirectional TVS tubes V9-V16 use SiC-based transient suppression diodes;

[0020] In the D5-D6 branch, D5 and D6 are connected in series, the cathode of the diode D5 is connected to the output end of the second decoupling circuit, the bidirectional TVS tube is not polarity-specific, V9 and V10 are connected in series, V11 and V12 are connected in series, V9 and V11 are connected to the anode of the diode D6, and V10 and V12 are connected to GND.

[0021] In the D7-D8 branch, D7 and D8 are connected in series, the anode of diode D7 is connected to the cathode of diode D5, the bidirectional TVS tube has no polarity, V13 and V14 are connected in series, V15 and V16 are connected in series, V13 and V15 are connected to the cathode of diode D8, and V14 and V16 are connected to GND.

[0022] Furthermore, in steady-state operation, only short-wave signals are transmitted and the transient protection circuit does not work; in the first-level transient protection circuit, the DC breakdown voltage parameter of the gas discharge tube G1 is greater than the maximum operating voltage of the short-wave signal, and the varistor voltage of the varistor VR1~VR4 is greater than the maximum operating voltage of the short-wave signal; in the second-level and third-level transient protection circuits, the breakdown voltage of the bidirectional TVS tube after series connection is greater than the maximum operating voltage of the short-wave signal, thereby ensuring that the starting thresholds of the first-level to third-level transient protection circuits are all greater than the maximum operating voltage of the short-wave signal, thereby avoiding false triggering.

[0023] Furthermore, the lightning electromagnetic pulse is protected by the level I and level II transient protection circuits and filter circuits, and the response timing is:

[0024] The high-pass filter effectively cuts off most of the lightning electromagnetic pulses in the I and II level transient protection circuits. When the lightning electromagnetic pulse arrives, the II level transient protection circuit responds first, the TVS tube breaks down and clamps, and the clamping voltage after the II transient protection circuit responds plus the voltage division of the resistor in the first decoupling circuit will be greater than the breakdown voltage of the I level transient protection circuit, thereby ensuring that the I level transient protection circuit responds quickly and breaks down;

[0025] After the Level I transient protection circuit responds, most of the pulse energy is discharged by it; the TVS tube in the Level II transient protection circuit is turned off first after the lightning pulse passes; in the Level I transient protection circuit, the gas discharge tube is designed to be connected in series with a varistor to reduce the current in the gas discharge tube and achieve rapid shutdown of the gas discharge tube.

[0026] Furthermore, the nuclear power electromagnetic pulse is protected by the level I and level II transient protection circuits, the filter circuit and the level III transient protection circuit, and the response timing is:

[0027] The high-frequency part of the nuclear electromagnetic pulse is protected by the level III transient circuit. When the nuclear electromagnetic pulse arrives, the level III transient protection circuit responds first. The sum of the clamping voltage of the level III transient protection circuit after breakdown and the resistance voltage in the second coupling circuit is greater than the breakdown voltage of the level II transient protection circuit, thereby achieving rapid breakdown of the level II transient protection circuit. Similarly, after the level II transient protection circuit breaks down, the sum of the clamping voltage of the level II transient protection circuit after breakdown and the resistance voltage in the first coupling circuit is greater than the breakdown voltage of the level I transient protection circuit, thereby causing the level I transient protection circuit to quickly break down. The protection mechanism is the same as that of the lightning electromagnetic pulse. After the nuclear electromagnetic pulse passes, the level III, level II, and level I transient protection circuits are shut down in sequence.

[0028] The beneficial effects of the present invention compared with the prior art are:

[0029] (1) The shortwave strong electromagnetic pulse suppression circuit of the present invention can protect against strong electromagnetic pulses during the operation of the shortwave radio station, thereby ensuring the real-time communication of the shortwave radio station when there is strong electromagnetic pulse interference;

[0030] (2) The short-wave strong electromagnetic pulse suppression circuit of the present invention can be used in short-wave radio stations with a power of more than kW, and has low insertion loss during high-power short-wave communication;

[0031] (3) The short-wave strong electromagnetic pulse suppression circuit of the present invention can not only protect against 10kA, us-level lightning electromagnetic pulses, but also protect against 1kA, ns-level nuclear power electromagnetic pulses.

[0032] (4) The short-wave strong electromagnetic pulse suppression circuit of the present invention adopts multi-level transient protection, and the residual voltage is very low. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of a high-power, low-residual-voltage, short-wave, strong electromagnetic pulse suppression circuit of the present invention; DETAILED DESCRIPTION

[0034] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0035] The present invention adds a shortwave strong electromagnetic pulse suppression circuit between the shortwave radio antenna and the receiver. When the radio works normally, the insertion loss of the suppression circuit should be very low to ensure the high-efficiency transmission of the shortwave signal; when encountering a strong electromagnetic pulse attack such as lightning or nuclear power, the suppression circuit can discharge the strong electromagnetic pulse to ensure that the voltage entering the receiver is within its safe voltage range, while ensuring the normal transmission of the shortwave signal. The circuit of the present invention can be widely used in various shortwave radio stations, and can greatly improve the strong electromagnetic environment survival ability and anti-interference ability of the shortwave radio station.

[0036] like Figure 1 As shown, a high-power, low-residual-voltage, short-wave, strong electromagnetic pulse suppression circuit proposed by the present invention includes a level I transient protection circuit, a level II transient protection circuit, a filtering circuit, a level III transient protection circuit and a decoupling circuit.

[0037] The level I transient protection circuit is realized by connecting a gas discharge tube and a varistor in parallel, and is used to protect the low-frequency part of a lightning electromagnetic pulse or a nuclear electromagnetic pulse, and its output end is connected to a first decoupling circuit;

[0038] The first decoupling circuit is used for the response timing and current shunting control of the first-level transient protection circuit and the second-level transient protection circuit, and the output end is connected to the second-level transient protection circuit;

[0039] The level II transient protection circuit is a voltage clamp circuit composed of a low-capacitance diode and a TVS tube, which is used to further protect the residual energy of the level I transient protection circuit. Its output end is connected to the filter circuit;

[0040] The filter circuit is a high-pass filter composed of LC. The cut-off frequency of the high-pass filter is designed to be 62.5KHz. On the one hand, it ensures the low insertion loss transmission of short-wave signals (2MHz-30MHz). On the other hand, it further filters out the residual low-frequency (0-62.5kHz) interference of the previous two-stage transient protection circuits. The output of the filter circuit is connected to the second decoupling circuit.

[0041] The second decoupling circuit is used for the response timing and current shunting control of the level II transient protection circuit and the level III transient protection circuit, and the output end is connected to the level III transient protection circuit;

[0042] The Level III transient protection circuit is a fast-response clamping circuit composed of a low-capacitance diode and a bidirectional TVS tube. It is used to protect the high-frequency part of nuclear power electromagnetic pulses and clamp the residual voltage at a lower level.

[0043] Specifically,

[0044] The I-level transient protection circuit includes a gas discharge tube G1 and four parallel varistors VR1-VR4, wherein one end of the gas discharge tube is connected to the signal terminal SIG and the other end is connected to the varistor, and is used to protect against lightning pulses with a large flow rate of 10kA at the us level.

[0045] The first decoupling circuit includes resistors R1 and R2 connected in parallel, one end of which is connected to the signal terminal SIG, and the other end of which is connected to the level II transient protection circuit as the output end of the first decoupling circuit.

[0046] The II-level transient protection circuit includes low-capacitance diodes D1-D4 and 8 bidirectional TVS tubes V1-V8 (bidirectional transient suppression diodes), wherein the anodes of the D1-D2 branch diodes are connected to the TVS tubes, and the cathodes of the D3-D4 branch diodes are connected to the TVS tubes. The residual energy of the I-level transient protection circuit can be further protected.

[0047] In the II-level transient protection circuit, in the D1-D2 branch, D1 and D2 are connected in series, the cathode of the diode D1 is connected to the output end of the first decoupling circuit, the bidirectional TVS tube is not polarity-specific, V1 and V2 are connected in series, V3 and V4 are connected in series, V1 and V3 are connected to the anode of the diode D2 after being connected, and V2 and V4 are connected to GND after being connected; in the D3-D4 branch, D3 and D4 are connected in series, the anode of the diode D3 is connected to the cathode of the diode D1, the TVS tube is not polarity-specific, V5 and V6 are connected in series, V7 and V8 are connected in series, V5 and V7 are connected to the cathode of the diode D4 after being connected, and V6 and V8 are connected to GND after being connected;

[0048] The filter circuit includes L1~L2, C1~C2, and forms a 4th-order high-pass filter circuit, which ensures low insertion loss transmission of short-wave signals on the one hand, and can filter the residual low-frequency interference of the previous two stages on the other hand. After C1 and C2 are connected in series, one end is connected to the anode of D3 in the level II transient protection circuit, and the other end is connected to the resistor R3 of the second decoupling circuit. One end of L1 is connected between C1 and C2, and the other end is connected to GND. One end of L2 is connected between C2 and the resistor R3, and the other end is connected to GND.

[0049] The second decoupling circuit includes a resistor R3, one end of which is connected to C3 in the filter circuit, and the other end of which is connected to the level III transient protection circuit.

[0050] The III-level transient protection circuit includes low-capacitance diodes D5-D8 and eight bidirectional TVS tubes V9-V16 (Sic-based transient suppression diodes, referred to as Sic-TVS), and the connection method is consistent with the II-level transient protection circuit, but the TVS tube is Sic-TVS. It is used to protect against nanosecond-level fast-edge nuclear electromagnetic pulses and clamp the residual voltage at a lower level.

[0051] In the level III transient protection circuit, in the D5-D6 branch, D5 and D6 are connected in series, the cathode of diode D5 is connected to the output end of the second decoupling circuit, the bidirectional TVS tube is not polarity-sensitive, V9 and V10 are connected in series, V11 and V12 are connected in series, V9 and V11 are connected to the anode of diode D6 after being connected, and V10 and V12 are connected to GND after being connected; in the D7-D8 branch, D7 and D8 are connected in series, the anode of diode D7 is connected to the cathode of diode D5, the bidirectional TVS tube is not polarity-sensitive, V13 and V14 are connected in series, V15 and V16 are connected in series, V13 and V15 are connected to the cathode of diode D8 after being connected, and V14 and V16 are connected to GND after being connected.

[0052] In steady-state operation, only short-wave signals are transmitted and the transient protection circuit does not work; in the first-level transient protection circuit, the DC breakdown voltage parameter of the gas discharge tube G1 is greater than the maximum operating voltage of the short-wave signal, and the varistor voltage of the varistor VR1~VR4 is greater than the maximum operating voltage of the short-wave signal; in the second-level and third-level transient protection circuits, the breakdown voltage of the bidirectional TVS tube after series connection is greater than the maximum operating voltage of the short-wave signal, thereby ensuring that the starting thresholds of the first-level to third-level transient protection circuits are all greater than the maximum operating voltage of the short-wave signal, avoiding false triggering.

[0053] The lightning electromagnetic pulse is protected by the Level I and Level II transient protection circuits and filter circuits, and the response sequence is:

[0054] 99% of the spectrum energy of lightning electromagnetic pulse is concentrated in the frequency band of 0-50kHz. The cut-off frequency of the high-pass filter is designed to be 62.5kHz, which effectively cuts off most of the lightning electromagnetic pulses in the I and II level transient protection circuits. Since the TVS tube of the II level transient protection circuit has a faster response speed and a low-capacitance diode is designed in series, the distributed capacitance of the II level transient protection circuit is lower, thereby further improving its response speed. Therefore, when the lightning electromagnetic pulse arrives, the II level transient protection circuit responds first, the TVS tube breaks down and clamps, and the clamping voltage after the II level transient protection circuit responds plus the voltage division of the resistor in the first decoupling circuit will be greater than the breakdown voltage of the I level transient protection circuit, thereby ensuring that the I level transient protection circuit responds quickly and breaks down. The selection of the decoupling resistor in the first decoupling circuit must ensure that the pulse current on the resistor (i.e., the pulse current of the II level transient protection circuit) is less than the maximum pulse current of the TVS tube in the II level transient protection circuit. After the I level transient protection circuit responds, most of the pulse energy is discharged by it. The TVS tube in the level II transient protection circuit is turned off first after the lightning pulse passes. The gas discharge tube in the level I transient protection circuit cannot be turned off when the voltage across it is greater than 20V after breakdown, while the short-wave working signal voltage is much greater than 20V. By designing the gas discharge tube to be connected in series with a varistor and reducing the current in the gas discharge tube, the gas discharge tube can be turned off quickly.

[0055] The nuclear power electromagnetic pulse is protected by the level I and level II transient protection circuits, filter circuits and level III transient protection circuits. The response sequence is:

[0056] 99% of the energy of the nuclear electromagnetic pulse spectrum is concentrated in the frequency band of 0-20MHz. The high-pass filter cutoff frequency is designed to be 62.5kHz. It cannot suppress nuclear electromagnetic pulses with frequencies higher than 62.5kHz. This part of nuclear electromagnetic pulses is protected by the level III transient circuit. The TVS tube in the level III transient protection circuit is a SiC-based TVS tube with a faster response speed. Therefore, when the nuclear electromagnetic pulse arrives, the level III transient protection circuit responds first, and the sum of the clamping voltage after the breakdown of the level III transient protection circuit and the resistance voltage in the second coupling circuit is greater than the breakdown voltage of the level II transient protection circuit, thereby achieving rapid breakdown of the level II transient protection circuit. Similarly, after the breakdown of the level II transient protection circuit, the sum of the clamping voltage after the breakdown of the level II transient protection circuit and the resistance voltage in the first coupling circuit is greater than the breakdown voltage of the level I transient protection circuit, which makes the level I transient protection circuit quickly break down. The protection mechanism is the same as that of lightning electromagnetic pulses. After the nuclear electromagnetic pulse passes, the level III, level II, and level I transient protection circuits are shut down in sequence.

[0057] Embodiment 1:

[0058] The transient protection process, insertion loss design and steady-state operation design of the short-wave strong electromagnetic pulse suppression circuit are explained below in conjunction with the accompanying drawings.

[0059] The core of transient protection design lies in the connection and matching of breakdown voltage, clamping voltage and maximum pulse current of each level of transient protection circuit. The lightning current 10kA (8 / 20us) and nuclear power current 1kA (20 / 500ns) are the transient protection design targets.

[0060] The lightning current pulse is 10kA (8 / 20us), which is mainly discharged through the level I and level II transient protection circuits and filter circuits. The response timing is:

[0061] The high-pass filter effectively cuts off most of the lightning electromagnetic pulses in the I and II level transient protection circuits. When the lightning electromagnetic pulse arrives, the II level transient protection circuit responds first, the TVS tube breaks down and clamps, and the clamping voltage after the II transient protection circuit responds plus the voltage division of the resistor in the first decoupling circuit will be greater than the breakdown voltage of the I level transient protection circuit, thereby ensuring that the I level transient protection circuit responds quickly and breaks down;

[0062] After the Level I transient protection circuit responds, most of the pulse energy is discharged by it; the TVS tube in the Level II transient protection circuit is turned off first after the lightning pulse passes; in the Level I transient protection circuit, the gas discharge tube is designed to be connected in series with a varistor to reduce the current in the gas discharge tube and achieve rapid shutdown of the gas discharge tube.

[0063] The nuclear power current pulse is 1kA (20 / 500ns), the low frequency part is discharged through the level I and II transient protection circuits and filter circuits, and the high frequency part is discharged through the level III transient protection circuit. Since the level III transient protection circuit uses Sic-TVS tubes, the response time reaches several hundred ps, which can quickly respond to ns-level nuclear power electromagnetic pulses.

[0064] The response timing is:

[0065] The high-frequency part of the nuclear electromagnetic pulse is protected by the level III transient circuit. When the nuclear electromagnetic pulse arrives, the level III transient protection circuit responds first. The sum of the clamping voltage of the level III transient protection circuit after breakdown and the resistance voltage in the second coupling circuit is greater than the breakdown voltage of the level II transient protection circuit, thereby achieving rapid breakdown of the level II transient protection circuit. Similarly, after the level II transient protection circuit breaks down, the sum of the clamping voltage of the level II transient protection circuit after breakdown and the resistance voltage in the first coupling circuit is greater than the breakdown voltage of the level I transient protection circuit, thereby causing the level I transient protection circuit to quickly break down. The protection mechanism is the same as that of the lightning electromagnetic pulse. After the nuclear electromagnetic pulse passes, the level III, level II, and level I transient protection circuits are shut down in sequence.

[0066] The triggering sequence of each transient protection circuit depends on the selection of decoupling impedance between each level. Assume that the maximum pulse current design value of the TVS branch in the level II transient protection circuit is I II In order to ensure that the TVS tube current is less than its maximum pulse current, it is assumed that after the TVS tube branch is started, the total current of the parallel branch of R1 and R2 is I II , the transient voltage on the resistor with a resistance value of R is Δu R =R*i. Thus, the transient voltage division ΔU of the resistor can be calculated. The clamping voltage U of the TVS branch is known. C , select the starting voltage U of the gas discharge tube G1 and the varistor VR1~VR4 S When C +ΔU>>U S That is, the clamping voltage after the TVS branch is started plus the transient voltage division of the decoupling branch is much larger than the starting voltage of the previous transient device, thereby ensuring that the previous stage starts quickly after the next stage is started, and ensuring that the current of the next stage is not greater than its maximum pulse current.

[0067] In order to ensure low insertion loss, the design order should be reduced as much as possible. At the same time, in order to ensure that more lightning electromagnetic pulses are filtered out, the filter order should be increased as much as possible. Combining the two design indicators, a fourth-order high-pass filter is designed. Since the highest frequency of lightning pulses is 62.5KHz, and the starting frequency of short-wave signals is 2MHz, the insertion loss of the high-pass filter is designed to be less than 0.5dB when the passband is above 2MHz. The cutoff frequency of the filter is 62.5KHz, and the insertion loss of the stopband 0-62.5kHz is greater than 20dB, that is, the stopband has a 10-fold suppression ability against lightning electromagnetic pulses.

[0068] The core components that affect insertion loss are resistors R1~R3 ​​and capacitors C1~C2 in the signal path. The equivalent resistance ESR of the resistors and capacitors generates heat loss to form insertion loss. The effective current in the signal path is the effective current of the shortwave radio when it is working normally. Assuming that the shortwave transmission power is P and the shortwave working impedance is R (50 ohms), according to The maximum operating voltage can be obtained according to The effective current can be obtained. If the effective current of the path and the resistance value and the equivalent resistance ESR of the capacitor are known, the heat loss can be obtained.

[0069] In steady-state operation, two aspects are considered. First, when the short-wave signal is transmitted at rated power, the transient protection device cannot be activated, and the leakage current is small and the insertion loss is low. Second, when the short-wave signal is transmitted at rated power, the voltage and current of the resistor, capacitor, inductor and other devices meet the device's withstand voltage and current capabilities. Therefore, in the first-level transient protection circuit, the DC breakdown voltage parameter of the gas discharge tube should be greater than the maximum value of the short-wave signal working voltage, and the varistor voltage should be greater than the maximum value of the short-wave signal working voltage; in the second-level and third-level transient protection circuits, the reverse working voltage of the TVS after series connection should be greater than the maximum value of the short-wave signal working voltage. This ensures that the transient protection start-up threshold of each branch is greater than the short-wave signal working voltage, ensuring false triggering.

[0070] Embodiment 2:

[0071] According to the present invention, a short-wave strong electromagnetic pulse suppressor circuit with a transmission power of 1200W is designed, and the implementation effect is as follows:

[0072] The response current timing waveforms of each level of transient protection circuits after the injection of 10kA (8 / 20us) lightning current were verified by simulation. When the rising edge of the lightning electromagnetic pulse arrives, the level II transient protection circuit breaks down first, and the maximum current is 560A, which is much smaller than the maximum pulse current design value of 786A@8 / 20us of the level II transient protection circuit. When the pulse current of the level II transient protection circuit reaches the maximum, the level I transient protection circuit breaks down, and the pulse current of the level I transient protection circuit rises rapidly, reaching a maximum of about 10kA. After the level I transient protection circuit breaks down, the pulse current of the level II transient protection circuit gradually decreases to zero to achieve shutdown, and the level I transient protection circuit is also quickly shut down after the lightning pulse passes. The maximum residual voltage monitored at the output end is less than 400V. The characteristic impedance of the shortwave radio is 50 ohms, and the maximum operating voltage is 346.4V when the transmission power is 1200W. After the strong electromagnetic pulse suppression circuit designed by the present invention injects a 10kA lightning electromagnetic pulse, the residual voltage is less than 400V, which is only 1.15 times the maximum working voltage of the shortwave radio station, and can achieve effective protection for the shortwave radio station.

[0073] The response current timing waveforms of each level of transient protection circuits after the injection of nuclear power current 1kA (20 / 500ns) were verified by simulation. When the rising edge of the nuclear power electromagnetic pulse arrives, the level III transient protection circuit breaks down first, and the maximum pulse current is 250A. When the current in the level III transient protection circuit rises rapidly, the level II transient protection circuit breaks down, and the maximum pulse current is 650A. At this time, the level III transient protection circuit is gradually shut down, and the pulse current decreases. When the current in the level II transient protection circuit decreases, the level I transient protection circuit is broken down, and the maximum pulse current is 500A. At this time, the level III transient protection circuit has been shut down, and the level II transient protection circuit is also shut down. When the nuclear electromagnetic pulse passes, the level I transient protection circuit is also quickly shut down. The maximum residual voltage monitored at the output end is less than 500V. When the shortwave radio transmission power is 1200W, the maximum operating voltage is 346.4V. The residual voltage is 1.44 times the maximum operating voltage of the shortwave radio station. Since the duration of the nuclear electromagnetic pulse is only in the ns level, it will not cause interference to the shortwave radio station.

[0074] Parts of the present invention that are not described in detail belong to common knowledge among those skilled in the art.

Claims

1. A high-power, low-residual-voltage, short-wave, strong electromagnetic pulse suppression circuit, characterized in that include: Level I transient protection circuit, first decoupling circuit, level II transient protection circuit, filtering circuit, second decoupling circuit and level III transient protection circuit; The level I transient protection circuit is realized by connecting a gas discharge tube and a varistor in parallel, and is used to protect the low-frequency part of a lightning electromagnetic pulse or a nuclear electromagnetic pulse, and its output end is connected to a first decoupling circuit; The first decoupling circuit is used for the response timing and current shunting control of the first-level transient protection circuit and the second-level transient protection circuit, and the output end is connected to the second-level transient protection circuit; The level II transient protection circuit is a voltage clamp circuit composed of a low-capacitance diode and a bidirectional TVS tube, which is used to further protect the residual energy of the level I transient protection circuit. Its output end is connected to the filter circuit; The filter circuit is a high-pass filter composed of LC. The filter circuit ensures low insertion loss transmission of short-wave signals. It is also used to filter out residual low-frequency interference from the previous two-stage transient protection circuits. The output of the filter circuit is connected to the second decoupling circuit. The second decoupling circuit is used for the response timing and current shunting control of the level II transient protection circuit and the level III transient protection circuit, and the output end is connected to the level III transient protection circuit; The Level III transient protection circuit is a fast-response clamping circuit composed of a low-capacitance diode and a bidirectional TVS tube. It is used to protect the high-frequency part of nuclear power electromagnetic pulses and clamp the residual voltage at a lower level.

2. According to claim 1, a high-power, low-residual-voltage, short-wave, strong electromagnetic pulse suppression circuit is characterized in that: The level I transient protection circuit comprises a gas discharge tube G1 and four parallel varistors VR1-VR4, wherein one end of the gas discharge tube G1 is connected to the signal terminal SIG, and the other end is grounded through the parallel varistors VR1-VR4.

3. A high-power, low-residual-voltage, short-wave, strong electromagnetic pulse suppression circuit according to claim 1, characterized in that: The first decoupling circuit includes resistors R1 and R2 connected in parallel, one end of which is connected to the signal terminal SIG, and the other end of which is connected to the level II transient protection circuit as the output end of the first decoupling circuit.

4. The high-power, low-residual-voltage, short-wave, strong electromagnetic pulse suppression circuit according to claim 1 is characterized in that: The II-level transient protection circuit includes low-capacitance diodes D1-D4 and 8 bidirectional TVS tubes V1-V8, wherein in the D1-D2 branch, D1 and D2 are connected in series, the cathode of the diode D1 is connected to the output end of the first decoupling circuit, the bidirectional TVS tubes are polarity-independent, V1 and V2 are connected in series, V3 and V4 are connected in series, V1 and V3 are connected to the anode of the diode D2, and V2 and V4 are connected to GND; In the D3-D4 branch, D3 and D4 are connected in series, the anode of diode D3 is connected to the cathode of diode D1, the TVS tube has no polarity, V5 and V6 are connected in series, V7 and V8 are connected in series, V5 and V7 are connected to the cathode of diode D4, and V6 and V8 are connected to GND. The bidirectional TVS tubes V1 to V8 are bidirectional transient suppression diodes.

5. A high-power, low-residual-voltage, short-wave, strong electromagnetic pulse suppression circuit according to claim 4, characterized in that: The filter circuit includes inductors L1-L2 and capacitors C1-C2, forming a 4th-order high-pass filter circuit, wherein C1 and C2 are connected in series, one end of which is connected to the anode of D3 in the level II transient protection circuit, and the other end is connected to the resistor R3 of the second decoupling circuit, one end of L1 is connected between C1 and C2, and the other end is connected to GND, and one end of L2 is connected between C2 and the resistor R3, and the other end is connected to GND.

6. A high-power, low-residual-voltage, short-wave, strong electromagnetic pulse suppression circuit according to claim 1, characterized in that: The second decoupling circuit includes a resistor R3, one end of which is connected to C3 in the filter circuit, and the other end of which is connected to the level III transient protection circuit.

7. The high-power, low-residual-voltage, short-wave, strong electromagnetic pulse suppression circuit according to claim 1 is characterized in that: The III-level transient protection circuit includes low-capacitance diodes D5-D8 and 8 bidirectional TVS tubes V9-V16, and the bidirectional TVS tubes V9-V16 use SiC-based transient suppression diodes; In the D5-D6 branch, D5 and D6 are connected in series, the cathode of the diode D5 is connected to the output end of the second decoupling circuit, the bidirectional TVS tube is not polarity-specific, V9 and V10 are connected in series, V11 and V12 are connected in series, V9 and V11 are connected to the anode of the diode D6, and V10 and V12 are connected to GND. In the D7-D8 branch, D7 and D8 are connected in series, the anode of diode D7 is connected to the cathode of diode D5, the bidirectional TVS tube has no polarity, V13 and V14 are connected in series, V15 and V16 are connected in series, V13 and V15 are connected to the cathode of diode D8, and V14 and V16 are connected to GND.

8. The high-power, low-residual-voltage, short-wave, strong electromagnetic pulse suppression circuit according to claim 3 is characterized in that: In steady-state operation, only short-wave signals are transmitted and the transient protection circuit does not work; in the first-level transient protection circuit, the DC breakdown voltage parameter of the gas discharge tube G1 is greater than the maximum operating voltage of the short-wave signal, and the varistor voltage of the varistor VR1~VR4 is greater than the maximum operating voltage of the short-wave signal; in the second-level and third-level transient protection circuits, the breakdown voltage of the bidirectional TVS tube after series connection is greater than the maximum operating voltage of the short-wave signal, thereby ensuring that the starting thresholds of the first-level to third-level transient protection circuits are all greater than the maximum operating voltage of the short-wave signal, avoiding false triggering.

9. The high-power, low-residual-voltage, short-wave, strong electromagnetic pulse suppression circuit according to claim 1 is characterized in that: The lightning electromagnetic pulse is protected by the Level I and Level II transient protection circuits and filter circuits, and the response sequence is: The high-pass filter effectively cuts off most of the lightning electromagnetic pulses in the I and II level transient protection circuits. When the lightning electromagnetic pulse arrives, the II level transient protection circuit responds first, the TVS tube breaks down and clamps, and the clamping voltage after the II transient protection circuit responds plus the voltage division of the resistor in the first decoupling circuit will be greater than the breakdown voltage of the I level transient protection circuit, thereby ensuring that the I level transient protection circuit responds quickly and breaks down; After the Level I transient protection circuit responds, most of the pulse energy is discharged by it; the TVS tube in the Level II transient protection circuit is turned off first after the lightning pulse passes; in the Level I transient protection circuit, the gas discharge tube is designed to be connected in series with a varistor to reduce the current in the gas discharge tube and achieve rapid shutdown of the gas discharge tube.

10. The high-power, low-residual-voltage, short-wave, strong electromagnetic pulse suppression circuit according to claim 1, characterized in that: The nuclear power electromagnetic pulse is protected by the level I and level II transient protection circuits, filter circuits and level III transient protection circuits. The response sequence is: The high-frequency part of the nuclear electromagnetic pulse is protected by the level III transient circuit. When the nuclear electromagnetic pulse arrives, the level III transient protection circuit responds first. The sum of the clamping voltage of the level III transient protection circuit after breakdown and the resistance voltage in the second coupling circuit is greater than the breakdown voltage of the level II transient protection circuit, thereby achieving rapid breakdown of the level II transient protection circuit. Similarly, after the level II transient protection circuit breaks down, the sum of the clamping voltage of the level II transient protection circuit after breakdown and the resistance voltage in the first coupling circuit is greater than the breakdown voltage of the level I transient protection circuit, thereby causing the level I transient protection circuit to quickly break down. The protection mechanism is the same as that of the lightning electromagnetic pulse. After the nuclear electromagnetic pulse passes, the level III, level II, and level I transient protection circuits are shut down in sequence.

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