Short-wave strong electromagnetic pulse suppression circuit with direct current and control functions

Abstract

The invention discloses a short-wave strong electromagnetic pulse suppression circuit with direct current and control functions. The short-wave strong electromagnetic pulse suppression circuit comprises an I-stage transient protection circuit, a three-signal circuit and an II-stage transient protection circuit, the I-stage transient protection circuit is formed by connecting two stages of gas discharge tubes in series and is used for protecting a low-frequency part in the lightning electromagnetic pulse or the nuclear power electromagnetic pulse, and the output end of the I-stage transient protection circuit is connected with the three-signal circuit; the three-signal circuit provides a path for transmission of the short-wave signal, the direct-current signal and the control signal and carries out transient protection, and the output end of the three-signal circuit is connected with the II-stage transient protection circuit; and the II-stage transient protection circuit is a voltage clamping circuit consisting of a low-capacitance diode and a bidirectional transient suppression diode, and is used for protecting a high-frequency part in the lightning electromagnetic pulse or the nuclear power electromagnetic pulse and clamping the residual voltage at a relatively low level. The device can effectively protect thunder and lightning and nuclear power electromagnetic pulses, has the characteristics of small insertion loss, low residual voltage and the like, and can greatly improve the strong electromagnetic environment viability and anti-interference capability of a short-wave radio station.

Description

Technical Field

[0001] The invention relates to a short-wave strong electromagnetic pulse suppression circuit with direct current and control functions, 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 operating frequency of shortwave communication is generally 2MHz-30MHz. The main disadvantage of shortwave communication is that it is easily interfered by natural or man-made electromagnetic pulses. 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 radio. Therefore, it is necessary to install a shortwave strong electromagnetic pulse suppression circuit (hereinafter referred to as shortwave suppression circuit) between the shortwave radio antenna and the receiver. When there is no strong electromagnetic pulse attack, the shortwave suppression circuit does not work. When a strong electromagnetic pulse attacks, the shortwave suppression circuit suppresses the interference voltage within the safe voltage range.

[0003] Since there is a need for DC power supply and signal control in shortwave radio stations, the shortwave suppression circuit that needs to be installed in actual engineering applications also has the function of passing DC and control signals. The shortwave suppression circuit must first ensure that the transient protection will not be triggered by mistake during normal operation. Secondly, the shortwave signal, DC signal, and control signal are all transmitted efficiently, that is, the insertion loss is small. Finally, it is necessary to ensure effective protection during strong electromagnetic pulse attacks, that is, the residual voltage is low. Adding the function of passing DC will easily cause the transient protection device to be triggered by mistake. Improving the DC voltage resistance of the transient device will cause the residual voltage to be too high. Adding the control signal transmission function will increase the insertion loss of the suppression circuit and affect the decoupling design of each level of transient. Therefore, the shortwave suppression circuit with the transmission function of three signals (shortwave signal, DC signal, and control signal) is very challenging in the design of low insertion loss and low residual voltage. It is necessary to design a shortwave strong electromagnetic pulse suppression circuit that can pass DC voltage and control signals. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, to provide a shortwave strong electromagnetic pulse suppression circuit with DC and control functions, to solve the interference problems of strong electromagnetic pulses such as lightning electromagnetic pulses and nuclear power electromagnetic pulses in shortwave radio stations, and to ensure efficient transmission of shortwave signals, DC signals and control signals of shortwave radio stations.

[0005] The technical solution of the present invention is:

[0006] A short-wave strong electromagnetic pulse suppression circuit with DC and control functions, comprising: a level I transient protection circuit, a three-signal circuit and a level II transient protection circuit;

[0007] Level I transient protection circuit uses two-stage gas discharge tubes in series to protect the low-frequency part of lightning electromagnetic pulses or nuclear electromagnetic pulses, and its output end is connected to a three-signal circuit;

[0008] The three-signal circuit provides a path for the transmission of short-wave signals, DC signals, and control signals and performs transient protection. The output end of the three-signal circuit is connected to the level II transient protection circuit;

[0009] The Level II transient protection circuit is a voltage clamping circuit composed of a low-capacitance diode and a bidirectional transient suppression diode. It is used to protect the high-frequency part of lightning electromagnetic pulses or nuclear power electromagnetic pulses and clamp the residual voltage at a lower level.

[0010] Furthermore, the level I transient protection circuit includes a capacitor C1 and two gas discharge tubes G1-G2 connected in series, one end of the gas discharge tube G1 is connected to the signal terminal SIG, and the other end is connected to the gas discharge tube G2, and the capacitor C1 is connected in parallel with the gas discharge tube G1.

[0011] Furthermore, the three-signal circuit includes inductors L1 to L3, capacitor C2, resistor R1, and varistors VR1 and VR2;

[0012] One end of the capacitor C2 is connected to the signal end SIG, and the other end is connected to the output end OUT of the short-wave strong electromagnetic pulse suppression circuit; the inductor L1 and the resistor R1 are connected in parallel with the capacitor C2, the inductor L1 is used to pass direct current, and the resistor R1 is used to pass control signals; the input end of the resistor R1 is also grounded through the inductor L2 and the varistor VR1, and the output end of the resistor R1 is grounded through the inductor L3 and the varistor VR2;

[0013] Among them, L1~L3 and C2 form a bandpass filter circuit to filter out the out-of-band interference of the shortwave signal and ensure the transmission of the shortwave signal; the two branches VR1 and VR2 are used to discharge the residual energy of the level I transient protection circuit, among which L2 connected in series on VR1 and L3 connected in series on VR2 are used to raise the branch voltage to ensure that the level I transient protection circuit responds in time.

[0014] Furthermore, the class II transient protection circuit comprises low capacitance diodes D1 to D4 and four bidirectional TVS tubes V1 to V4; wherein the bidirectional TVS tubes are not polarity-specific, V1 is connected in series with V2, V3 is connected in series with V4, V1 is connected with V3, and V2 is connected with V4 and then connected to GND; wherein the low capacitance diodes D1 to D4 are connected end to end in a rectangular layout, one corner of the rectangle is connected to the output terminal OUT, and the opposite corner is connected to the bidirectional TVS tubes V1 and V3;

[0015] Level II transient protection circuits are used to protect against the high-frequency portion of lightning electromagnetic pulses or nuclear electromagnetic pulses and clamp the residual voltage at a lower level.

[0016] Furthermore, when the short-wave signal is transmitted, the transient protection circuit does not work; the DC breakdown voltage parameter of the gas discharge tubes G1-G2 is greater than the maximum working voltage of the short-wave signal, the varistor voltage of the varistors VR1 and VR2 is greater than the maximum working voltage of the short-wave signal, and the breakdown voltage of the bidirectional TVS tubes V1-V4 in the level II transient protection circuit after being connected in series is greater than the maximum working voltage of the short-wave signal, thereby ensuring that the start thresholds of the level I and level II transient protection circuits and the three-signal circuit are greater than the maximum working voltage of the short-wave signal, thereby avoiding false triggering;

[0017] The shortwave signal is transmitted to the output end through C2, and the insertion loss of capacitor C2 is less than the insertion loss value required by the shortwave signal; when the shortwave signal is transmitted at rated power, the withstand voltage values ​​of inductors L2 and L3 are greater than the maximum operating voltage of the shortwave signal.

[0018] Furthermore, when the DC signal is transmitted, the transient protection circuit does not work; the DC breakdown voltage parameter of the gas discharge tubes G1-G2 is greater than the maximum DC signal voltage, the maximum allowable DC voltage of the varistors VR1 and VR2 is greater than the maximum DC signal voltage, and the reverse working voltage of the bidirectional TVS tubes V1-V4 in the level II transient protection circuit after being connected in series is greater than the maximum DC signal voltage, thereby ensuring that the start thresholds of the level I and level II transient protection circuits and the three-signal circuit are greater than the maximum DC signal voltage, avoiding false triggering;

[0019] During DC signal transmission, the DC voltage is directly transmitted to the output end through L1. The DC loss depends on the DC resistance DCR value of L1. When the DC current is known, the loss of L1 is the DCR value multiplied by the square of the DC current value. During DC signal transmission, the value of L1 must ensure that the DC voltage drop generated by the DC current on the L1 DC resistance DCR meets the design index requirements.

[0020] Furthermore, when the control signal is transmitted, the transient protection circuit does not work; the control signal is transmitted to the output end through R1, and its current effective value is calculated according to the control signal waveform, and the loss value of the control signal is obtained by multiplying the square of the current effective value by the resistance value of R1; when the control signal is transmitted, the selection of R1 must ensure that the loss of the control signal meets the design requirements.

[0021] Furthermore, the lightning electromagnetic pulse is discharged step by step through the level I transient protection circuit, the three-signal circuit and the level II transient protection circuit, and the response sequence is: the level II transient protection circuit responds first, followed by the three-signal circuit, and finally the level I transient protection circuit responds;

[0022] After the lightning electromagnetic pulse is injected, the rapid current change generates transient high voltage on L3, which causes the voltage of the Level II transient protection circuit to rise rapidly and trigger first. The clamping voltage of the Level II transient protection circuit after triggering is relatively high, which drives VR2 to trigger; the clamping voltage after VR2 is triggered drives VR1 to trigger, and the clamping voltage after VR1 is triggered drives the gas discharge tube of the Level I transient protection circuit to trigger; G2 in the gas discharge tube is triggered first and then G1; after G1 is triggered, the Level I transient circuit is in a conducting state, and the energy is directly discharged by the gas discharge tube; most of the lightning electromagnetic pulse is discharged by the Level I transient circuit.

[0023] Furthermore, the nuclear power electromagnetic pulse is discharged step by step through the level I transient protection circuit, the three-signal circuit and the level II transient protection circuit, and the response sequence is: the level II transient protection circuit responds first, followed by the three-signal circuit, and finally the level I transient protection circuit responds;

[0024] After the nuclear power electromagnetic pulse is injected, the rapid current change generates transient high voltage on L3, which makes the voltage of the level II transient protection circuit rise rapidly and trigger first. The clamping voltage of the level II transient protection circuit after triggering is relatively high, which drives VR2 to trigger; the clamping voltage after VR2 is triggered drives VR1 to trigger, and the clamping voltage after VR1 is triggered drives the gas discharge tube of the level I transient protection circuit to trigger; G2 in the gas discharge tube is triggered first and then G1; after G1 is triggered, the level I transient branch is in a conducting state, and the energy is directly discharged by the gas discharge tube; most of the nuclear power electromagnetic pulse is discharged by the level II transient circuit.

[0025] Furthermore, suppose the capacitance of C1 and G1 in parallel is C G1 , the impedance is Z1, and the capacitance of G2 is C G2 , the impedance is Z2, Z1:Z2=C2:C1; let the capacitance of C1 be much larger than that of G2. When the lightning current pulse is injected, the two gas discharge tubes of the same specification divide the voltage, so that G2 is triggered first and G1 is triggered later, thereby avoiding the simultaneous triggering of the two gas discharge tubes to cause a higher residual voltage.

[0026] Furthermore, assuming that the maximum pulse current design value in the level II transient protection circuit is I II , assuming that the level II transient protection circuit is activated, the total current of the parallel branch of L1 and R1 is I II , the shunt value is calculated by impedance, the inductor impedance Z with inductance value L L =2πfL, f is the frequency of the pulse current, which is the inverse of the rising edge time of the pulse current, and the resistance impedance Z of the resistor R R =R, the current on L1 and R1 is inversely proportional to its impedance; the transient voltage on the inductor L is Δu L=L*di / dt, di / dt is the pulse current change rate, that is, the pulse current peak value / pulse current rising edge time; the transient voltage on the resistor R is Δu R =R*i; i is the peak value of the pulse current, so as to calculate the transient voltage division ΔU of the inductor and resistor;

[0027] The clamping voltage U of the Level II transient protection circuit is known C , when selecting the starting voltage U of the gas discharge tube and the varistor VR1 S When ensuring U C +ΔU>>U S That is, the clamping voltage after the start-up of the II-stage transient protection circuit plus the transient voltage division of the decoupling branch is much larger than the start-up voltage of the previous stage transient device, thereby ensuring that the previous stage starts quickly after the next stage starts, and ensuring that the current of the next stage is not greater than its maximum pulse current.

[0028] Furthermore, the insertion loss of the suppression circuit depends on C2. The shortwave signal is transmitted through C2. Assuming that the shortwave transmission power is P and the shortwave working impedance is R, according to Maximum available operating voltage U m ,according to Get the effective current I a ; Given the effective current in the path and the equivalent resistance ESR of the capacitor, obtain the heat loss.

[0029] The beneficial effects of the present invention compared with the prior art are:

[0030] (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;

[0031] (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;

[0032] (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.

[0033] (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

[0034] Figure 1 This is a schematic diagram of a short-wave strong electromagnetic pulse suppression circuit with direct current and control functions of the present invention; DETAILED DESCRIPTION

[0035] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0036] The circuit of the present invention can be widely used in various shortwave radio stations. It not only has the transmission function of shortwave signals, DC signals and control signals, but also can effectively protect against lightning electromagnetic pulses and nuclear power electromagnetic pulses, and has the characteristics of small insertion loss and low residual voltage. It has strong engineering practicality and can greatly improve the survival ability and anti-interference ability of shortwave radio stations in strong electromagnetic environments.

[0037] like Figure 1 As shown, the present invention proposes a short-wave strong electromagnetic pulse suppression circuit with DC and control functions, including a level I transient protection circuit, a three-signal circuit, and a level II transient protection circuit. Among them:

[0038] Level I transient protection circuit uses two-stage gas discharge tubes in series to protect the low-frequency part of lightning electromagnetic pulses or nuclear electromagnetic pulses, and its output end is connected to a three-signal circuit;

[0039] The three-signal circuit provides a path for the transmission of short-wave signals, DC signals, and control signals and performs transient protection. The output end of the three-signal circuit is connected to the level II transient protection circuit;

[0040] The Level II transient protection circuit is a voltage clamping circuit composed of a low-capacitance diode and a bidirectional transient suppression diode (TVS). It is used to protect the high-frequency part of lightning electromagnetic pulses or nuclear power electromagnetic pulses and clamp the residual voltage at a lower level.

[0041] Specifically, the I-level transient protection circuit includes a capacitor C1 and two gas discharge tubes G1-G2 connected in series, one end of the gas discharge tube G1 is connected to the signal terminal SIG, and the other end is connected to the gas discharge tube G2, and the capacitor C1 is connected in parallel with the gas discharge tube G1. It is used to protect against lightning pulses with a large flow rate of 10kA at the us level.

[0042] The three-signal circuit includes inductors L1 to L3, capacitor C2, resistor R1 and varistors VR1 and VR2; one end of the capacitor C2 is connected to the signal end SIG, and the other end is connected to the output end OUT of the short-wave strong electromagnetic pulse suppression circuit; the inductor L1 and the resistor R1 are connected in parallel with the capacitor C2, the inductor L1 is used to pass direct current, and the resistor R1 is used to pass control signals; the input end of the resistor R1 is also grounded through the inductor L2 and the varistor VR1, and the output end of the resistor R1 is grounded through the inductor L3 and the varistor VR2;

[0043] Among them, L1~L3 and C2 form a bandpass filter circuit to filter out the out-of-band interference of the shortwave signal and ensure the transmission of the shortwave signal; the two branches VR1 and VR2 are used to discharge the residual energy of the level I transient protection circuit, among which L2 connected in series on VR1 and L3 connected in series on VR2 are used to raise the branch voltage to ensure that the level I transient protection circuit responds in time.

[0044] The II-level transient protection circuit includes low-capacitance diodes D1-D4 and four bidirectional TVS tubes V1-V4; the bidirectional TVS tubes are not polarized, V1 and V2 are connected in series, V3 and V4 are connected in series, V1 and V3 are connected, and V2 and V4 are connected and then connected to GND; the D1-D4 low-capacitance diodes are connected end to end to form a rectangular layout, one corner of the rectangle is connected to the output terminal OUT, and the opposite corner is connected to the bidirectional TVS tubes V1 and V3; the II-level transient protection circuit is used to protect against the high-frequency part of lightning electromagnetic pulses or nuclear electromagnetic pulses, and clamp the residual voltage at a lower level.

[0045] When the short-wave signal is transmitted, the transient protection circuit does not work; the DC breakdown voltage parameter of the gas discharge tubes G1~G2 is greater than the maximum working voltage of the short-wave signal, the varistor voltage of the varistors VR1 and VR2 is greater than the maximum working voltage of the short-wave signal, and the breakdown voltage of the bidirectional TVS tubes V1~V4 in the II-level transient protection circuit after being connected in series is greater than the maximum working voltage of the short-wave signal, thereby ensuring that the start thresholds of the I-level, II-level transient protection circuits and the three-signal circuits are greater than the maximum working voltage of the short-wave signal, avoiding false triggering;

[0046] The shortwave signal is transmitted to the output end through C2. The selection of C2 should ensure low insertion loss transmission of shortwave signals of 2MHz to 30MHz. The equivalent resistance ESR of the capacitor generates heat loss to form insertion loss. The square of the effective working current of the shortwave signal multiplied by the ESR of the capacitor is the insertion loss of the capacitor. The insertion loss of capacitor C2 should be less than the insertion loss value required by the shortwave signal.

[0047] When the short-wave signal is transmitted at rated power, the withstand voltage of the inductor L2 and the inductor L3 devices should be greater than the maximum operating voltage of the short-wave signal.

[0048] When the DC signal is transmitted, the transient protection circuit does not work; the DC breakdown voltage parameter of the gas discharge tubes G1~G2 is greater than the maximum DC signal voltage, the maximum allowable DC voltage of the varistors VR1 and VR2 is greater than the maximum DC signal voltage, and the reverse working voltage of the bidirectional TVS tubes V1~V4 in the II-level transient protection circuit after being connected in series is greater than the maximum DC signal voltage, thereby ensuring that the start thresholds of the I-level and II-level transient protection circuits and the three-signal circuits are greater than the maximum DC signal voltage, avoiding false triggering;

[0049] During DC signal transmission, the DC voltage is directly transmitted to the output end through L1. The DC loss depends on the DC resistance DCR value of L1. When the DC current is known, the loss of L1 is the DCR value multiplied by the square of the DC current value. During DC signal transmission, the value of L1 must ensure that the DC voltage drop generated by the DC current on the L1 DC resistance DCR meets the design index requirements.

[0050] When the control signal is transmitted, the transient protection circuit does not work. The control signal voltage is low and generally does not trigger the transient protection circuit. The control signal is transmitted to the output end through R1, and its current effective value is calculated according to the control signal waveform. The square of the current effective value multiplied by the resistance value of R1 is the loss value of the control signal; when the control signal is transmitted, the selection of R1 must ensure that the loss of the control signal meets the design requirements.

[0051] The lightning electromagnetic pulse is discharged step by step through the level I transient protection circuit, the three-signal circuit and the level II transient protection circuit. The response sequence is: the level II transient protection circuit responds first, followed by the three-signal circuit, and finally the level I transient protection circuit responds.

[0052] After the lightning electromagnetic pulse is injected, the rapid current change generates transient high voltage on L3, which causes the voltage of the Level II transient protection circuit to rise rapidly and trigger first. The clamping voltage of the Level II transient protection circuit after triggering is relatively high, which drives VR2 to trigger; the clamping voltage after VR2 is triggered drives VR1 to trigger, and the clamping voltage after VR1 is triggered drives the gas discharge tube of the Level I transient protection circuit to trigger; G2 in the gas discharge tube is triggered first and then G1; after G1 is triggered, the Level I transient circuit is in a conducting state, and the energy is directly discharged by the gas discharge tube; most of the lightning electromagnetic pulse is discharged by the Level I transient circuit.

[0053] The nuclear power electromagnetic pulse is discharged step by step through the level I transient protection circuit, the three-signal circuit and the level II transient protection circuit. The response sequence is: the level II transient protection circuit responds first, followed by the three-signal circuit, and finally the level I transient protection circuit responds.

[0054] After the nuclear power electromagnetic pulse is injected, the rapid current change generates transient high voltage on L3, which makes the voltage of the level II transient protection circuit rise rapidly and trigger first. The clamping voltage of the level II transient protection circuit after triggering is relatively high, which drives VR2 to trigger; the clamping voltage after VR2 is triggered drives VR1 to trigger, and the clamping voltage after VR1 is triggered drives the gas discharge tube of the level I transient protection circuit to trigger; G2 in the gas discharge tube is triggered first and then G1; after G1 is triggered, the level I transient branch is in a conducting state, and the energy is directly discharged by the gas discharge tube; most of the nuclear power electromagnetic pulse is discharged by the level II transient circuit.

[0055] Example:

[0056] The following describes the transient protection process, insertion loss design, and three-signal (shortwave signal, DC signal, and control signal) transmission steady-state design of the shortwave strong electromagnetic pulse suppression circuit in conjunction with the accompanying drawings.

[0057] 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.

[0058] The lightning current pulse is 10kA (8 / 20us), which needs to be discharged step by step through the level I transient protection circuit, the three-signal circuit and the level II transient protection circuit. The response sequence is: the level II transient protection circuit responds first, followed by the three-signal circuit, and finally the level I transient protection circuit responds.

[0059] The second-level transient protection circuit is mainly composed of TVS tubes, which have fast response and stable clamping voltage. After the pulse current is injected, due to the existence of L3, the TVS tube branch is triggered first, and the clamping voltage after triggering is high, which drives VR2 to trigger. The clamping voltage after VR2 is triggered drives VR1 to trigger, and the clamping voltage after VR1 is triggered drives the gas discharge tube of the first-level transient protection circuit to trigger. In the gas discharge tube, G2 is triggered first and then G1. After triggering, the first-level transient branch is in the on state, and most of the energy is directly discharged by the gas discharge tube.

[0060] In the first-level transient protection circuit, there is a continuous flow phenomenon after the gas discharge tube is triggered and turned on. The continuous flow voltage can be checked in the manual and is generally 12V. Due to the DC signal transmission function, multiple gas discharge tubes need to be designed to avoid the DC voltage causing continuous flow and being unable to cut off the tube. The design principle is that the DC voltage is less than 12N, where N is the number of gas discharge tubes in series. The present invention uses two gas tubes in series, and the DC voltage can be <24V.

[0061] When multiple gas pipes are connected in series and triggered synchronously during transient protection, the impulse voltage will be superimposed, resulting in a very high residual voltage. Therefore, a hierarchical trigger is designed. Assume that the capacitance of C1 and G1 in parallel is C G1 , the impedance is Z1, and the capacitance of G2 is C G2 , the impedance is Z2, then according to Z=1 / 2πfc, we know that Z1:Z2=C2:C1. When designing, the capacitance of C1 is much larger than that of G2 (the capacitance of the gas discharge tube is about 1pf). When the lightning current pulse is injected, the two gas discharge tubes of the same specification divide the voltage, so that G2 is triggered first and G1 is triggered later, thus avoiding the high residual voltage caused by the simultaneous triggering of the two gas discharge tubes; f is the frequency of the pulse current, which is the reciprocal of the rising edge time of the pulse current.

[0062] The triggering sequence of each transient protection circuit depends on the selection of direct decoupling impedance at each level. Assume that the maximum pulse current design value in the level II transient protection circuit is I II , assuming that the level II transient protection circuit is activated, the total current of the parallel branch of L1 and R1 is I II, the shunt value is calculated by impedance, the inductor impedance Z with inductance value L L =2πfL, f is the frequency of the pulse current, which is the inverse of the rising edge time of the pulse current, and the resistance impedance Z of the resistor R R =R, the current on L1 and R1 is inversely proportional to its impedance; the transient voltage on the inductor L is Δu L =L*di / dt, di / dt is the pulse current change rate, that is, the pulse current peak value / pulse current rising edge time; the transient voltage on the resistor R is Δu R =R*i; i is the peak value of the pulse current, so as to calculate the transient voltage division ΔU of the inductor and resistor;

[0063] The clamping voltage U of the Level II transient protection circuit is known C , when selecting the starting voltage U of the gas discharge tube and the varistor VR1 S When ensuring U C +ΔU>>U S That is, the clamping voltage after the start-up of the II-stage transient protection circuit plus the transient voltage division of the decoupling branch is much larger than the start-up voltage of the previous stage transient device, thereby ensuring that the previous stage starts quickly after the next stage starts, and ensuring that the current of the next stage is not greater than its maximum pulse current.

[0064] The insertion loss of the circuit mainly depends on C2. The shortwave signal is mainly transmitted through C2. The equivalent resistance ESR of the capacitor generates heat loss to form insertion loss. Assuming that the shortwave transmission power is P and the shortwave working impedance is R (50Ω), then according to The maximum operating voltage can be obtained according to The effective current I a . The effective current I of the known path a And the equivalent resistance ESR of the capacitor, the heat loss can be obtained.

[0065] The DC voltage is transmitted directly to the output end through L1. The DC loss depends on the DCR value of L1 (check the manual). Given the DC current, the loss of L1 is the DCR value multiplied by the square of the DC current value.

[0066] The control signal is usually several tens of kHz and is transmitted to the output terminal through R1. The effective value of the current is calculated according to the waveform of the control signal, and the loss value of the control signal is obtained by multiplying the square and the resistance value of R1. Therefore, R1 should not be too large, and is generally 3Ω to 5Ω.

[0067] In the transmission of short-wave signals, 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, the DC breakdown voltage parameter of the gas discharge tube should be greater than the maximum value of the short-wave signal working voltage, the varistor's varistor voltage should be greater than the maximum value of the short-wave signal working voltage, and 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.

[0068] Parts of the present invention that are not described in detail belong to common knowledge among those skilled in the art.

Claims

1. A short-wave strong electromagnetic pulse suppression circuit with DC and control functions, characterized in that include: Class I transient protection circuits, three-signal circuits, and Class II transient protection circuits; Level I transient protection circuit uses two-stage gas discharge tubes in series to protect the low-frequency part of lightning electromagnetic pulses or nuclear electromagnetic pulses, and its output end is connected to a three-signal circuit; The three-signal circuit provides a path for the transmission of short-wave signals, DC signals, and control signals and performs transient protection. The output end of the three-signal circuit is connected to the level II transient protection circuit; The Level II transient protection circuit is a voltage clamping circuit composed of a low-capacitance diode and a bidirectional transient suppression diode. It is used to protect the high-frequency part of lightning electromagnetic pulses or nuclear power electromagnetic pulses and clamp the residual voltage at a lower level.

2. A short-wave strong electromagnetic pulse suppression circuit with DC and control functions according to claim 1, characterized in that: The level I transient protection circuit comprises a capacitor C1 and two gas discharge tubes G1-G2 connected in series, one end of the gas discharge tube G1 is connected to the signal terminal SIG, and the other end is connected to the gas discharge tube G2, and the capacitor C1 is connected in parallel with the gas discharge tube G1.

3. A short-wave strong electromagnetic pulse suppression circuit with DC and control functions according to claim 2, characterized in that: The three-signal circuit includes inductors L1 to L3, capacitor C2, resistor R1 and varistors VR1 and VR2; One end of the capacitor C2 is connected to the signal end SIG, and the other end is connected to the output end OUT of the short-wave strong electromagnetic pulse suppression circuit; the inductor L1 and the resistor R1 are connected in parallel with the capacitor C2, the inductor L1 is used to pass direct current, and the resistor R1 is used to pass control signals; the input end of the resistor R1 is also grounded through the inductor L2 and the varistor VR1, and the output end of the resistor R1 is grounded through the inductor L3 and the varistor VR2; Among them, L1~L3 and C2 form a bandpass filter circuit to filter out the out-of-band interference of the shortwave signal and ensure the transmission of the shortwave signal; the two branches VR1 and VR2 are used to discharge the residual energy of the level I transient protection circuit, among which L2 connected in series on VR1 and L3 connected in series on VR2 are used to raise the branch voltage to ensure that the level I transient protection circuit responds in time.

4. A short-wave strong electromagnetic pulse suppression circuit with DC and control functions according to claim 3, characterized in that: The class II transient protection circuit comprises low capacitance diodes D1 to D4 and four bidirectional TVS tubes V1 to V4; wherein the bidirectional TVS tubes are not polarity-specific, V1 and V2 are connected in series, V3 and V4 are connected in series, V1 and V3 are connected, and V2 and V4 are connected and then connected to GND; wherein the low capacitance diodes D1 to D4 are connected end to end in a rectangular layout, one corner of the rectangle is connected to the output terminal OUT, and the opposite corner is connected to the bidirectional TVS tubes V1 and V3; Level II transient protection circuits are used to protect against the high-frequency portion of lightning electromagnetic pulses or nuclear electromagnetic pulses and clamp the residual voltage at a lower level.

5. A short-wave strong electromagnetic pulse suppression circuit with DC and control functions according to claim 4, characterized in that: When the short-wave signal is transmitted, the transient protection circuit does not work; the DC breakdown voltage parameter of the gas discharge tubes G1~G2 is greater than the maximum working voltage of the short-wave signal, the varistor voltage of the varistors VR1 and VR2 is greater than the maximum working voltage of the short-wave signal, and the breakdown voltage of the bidirectional TVS tubes V1~V4 in the II-level transient protection circuit after being connected in series is greater than the maximum working voltage of the short-wave signal, thereby ensuring that the start thresholds of the I-level, II-level transient protection circuits and the three-signal circuits are greater than the maximum working voltage of the short-wave signal, avoiding false triggering; The shortwave signal is transmitted to the output end through C2, and the insertion loss of capacitor C2 is less than the insertion loss value required by the shortwave signal; when the shortwave signal is transmitted at rated power, the withstand voltage values ​​of inductors L2 and L3 are greater than the maximum operating voltage of the shortwave signal.

6. A short-wave strong electromagnetic pulse suppression circuit with DC and control functions according to claim 4, characterized in that: When the DC signal is transmitted, the transient protection circuit does not work; the DC breakdown voltage parameter of the gas discharge tubes G1~G2 is greater than the maximum DC signal voltage, the maximum allowable DC voltage of the varistors VR1 and VR2 is greater than the maximum DC signal voltage, and the reverse working voltage of the bidirectional TVS tubes V1~V4 in the II-level transient protection circuit after being connected in series is greater than the maximum DC signal voltage, thereby ensuring that the start thresholds of the I-level and II-level transient protection circuits and the three-signal circuits are greater than the maximum DC signal voltage, avoiding false triggering; During DC signal transmission, the DC voltage is directly transmitted to the output end through L1. The DC loss depends on the DC resistance DCR value of L1. When the DC current is known, the loss of L1 is the DCR value multiplied by the square of the DC current value. During DC signal transmission, the value of L1 must ensure that the DC voltage drop generated by the DC current on the L1 DC resistance DCR meets the design index requirements.

7. A short-wave strong electromagnetic pulse suppression circuit with DC and control functions according to claim 4, characterized in that: When the control signal is transmitted, the transient protection circuit does not work; the control signal is transmitted to the output end through R1, and its current effective value is calculated according to the control signal waveform. The loss value of the control signal is obtained by multiplying the square of the current effective value by the resistance value of R1; when the control signal is transmitted, the selection of R1 must ensure that the loss of the control signal meets the design requirements.

8. The short-wave strong electromagnetic pulse suppression circuit with DC and control functions according to claim 1 is characterized in that: The lightning electromagnetic pulse is discharged step by step through the level I transient protection circuit, the three-signal circuit and the level II transient protection circuit. The response sequence is: the level II transient protection circuit responds first, followed by the three-signal circuit, and finally the level I transient protection circuit responds. After the lightning electromagnetic pulse is injected, the rapid current change generates transient high voltage on L3, which causes the voltage of the Level II transient protection circuit to rise rapidly and trigger first. The clamping voltage of the Level II transient protection circuit after triggering is relatively high, which drives VR2 to trigger; the clamping voltage after VR2 is triggered drives VR1 to trigger, and the clamping voltage after VR1 is triggered drives the gas discharge tube of the Level I transient protection circuit to trigger; G2 in the gas discharge tube is triggered first and then G1; after G1 is triggered, the Level I transient circuit is in a conducting state, and the energy is directly discharged by the gas discharge tube; most of the lightning electromagnetic pulse is discharged by the Level I transient circuit.

9. A short-wave strong electromagnetic pulse suppression circuit with DC and control functions according to claim 8, characterized in that: The nuclear power electromagnetic pulse is discharged step by step through the level I transient protection circuit, the three-signal circuit and the level II transient protection circuit. The response sequence is: the level II transient protection circuit responds first, followed by the three-signal circuit, and finally the level I transient protection circuit responds. After the nuclear power electromagnetic pulse is injected, the rapid current change generates transient high voltage on L3, which makes the voltage of the level II transient protection circuit rise rapidly and trigger first. The clamping voltage of the level II transient protection circuit after triggering is relatively high, which drives VR2 to trigger; the clamping voltage after VR2 is triggered drives VR1 to trigger, and the clamping voltage after VR1 is triggered drives the gas discharge tube of the level I transient protection circuit to trigger; G2 in the gas discharge tube is triggered first and then G1; after G1 is triggered, the level I transient branch is in a conducting state, and the energy is directly discharged by the gas discharge tube; most of the nuclear power electromagnetic pulse is discharged by the level II transient circuit.

10. A short-wave strong electromagnetic pulse suppression circuit with DC and control functions according to claim 8 or 9, characterized in that: Assume that the capacitance of C1 and G1 in parallel is C G1 , the impedance is Z1, and the capacitance of G2 is C G2 , the impedance is Z2, Z1:Z2=C2:C1; let the capacitance of C1 be much larger than that of G2. When the lightning current pulse is injected, the two gas discharge tubes of the same specification divide the voltage, so that G2 is triggered first and G1 is triggered later, thereby avoiding the simultaneous triggering of the two gas discharge tubes to cause a higher residual voltage.

11. A short-wave strong electromagnetic pulse suppression circuit with DC and control functions according to claim 8 or 9, characterized in that: Assume that the maximum pulse current design value in the II-level transient protection circuit is I II , assuming that the level II transient protection circuit is activated, the total current of the parallel branch of L1 and R1 is I II , the shunt value is calculated by impedance, the inductor impedance Z with inductance value L L =2πfL, f is the frequency of the pulse current, which is the inverse of the rising edge time of the pulse current, and the resistance impedance Z of the resistor R R =R, the current on L1 and R1 is inversely proportional to its impedance; the transient voltage on the inductor L is Δu L =L*di / dt, di / dt is the pulse current change rate, that is, the pulse current peak value / pulse current rising edge time; the transient voltage on the resistor R is Δu R =R*i; i is the peak value of the pulse current, so as to calculate the transient voltage division ΔU of the inductor and resistor; The clamping voltage U of the Level II transient protection circuit is known C , select the starting voltage U of the gas discharge tube and varistor VR1 S When ensuring U C +ΔU>>U S That is, the clamping voltage after the start-up of the II-stage transient protection circuit plus the transient voltage division of the decoupling branch is much larger than the start-up voltage of the preceding transient device, thereby ensuring that after the following stage is started, the preceding stage starts quickly and the following stage current is not greater than its maximum pulse current.

12. A short-wave strong electromagnetic pulse suppression circuit with DC and control functions according to claim 8 or 9, characterized in that: The insertion loss of the suppression circuit depends on C2. The shortwave signal is transmitted through C2. Assuming that the shortwave transmission power is P and the shortwave working impedance is R, according to Maximum available operating voltage U m ,according to Get the effective current I a ; Knowing the effective current in the path and the equivalent resistance ESR of the capacitor, the heat loss is obtained.

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