An electrostatic discharge pulse suppression device for electromagnetic compatibility testing

Abstract

The application relates to an electrostatic discharge pulse suppression device for electromagnetic compatibility detection, which comprises a shielding packaging shell, an electrostatic discharge pulse suppression circuit board in the shielding packaging shell, and an A port and a B port at two ends of the shielding packaging shell, wherein the A port and the B port each comprise a 2-wire port, an 8-wire Ethernet port and a vehicle-mounted Ethernet port which are connected with each other, an A-end overvoltage protection unit, an A-end first-stage pulse suppression unit, an A-end second-stage pulse suppression unit, an A-end filtering decoupling unit, a B-end filtering decoupling unit, a B-end second-stage pulse suppression unit, a B-end first-stage pulse suppression unit and a B-end overvoltage protection unit are sequentially connected on the electrostatic discharge pulse suppression circuit board, the A port is an input end of the A-end overvoltage protection unit, the B port is an input end of the B-end overvoltage protection unit, and the shielding packaging shell is grounded. The electrostatic discharge pulse suppression process can be realized while the communication connection is not interrupted; the port versatility is high, and the applicability of the electromagnetic compatibility test is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to an electromagnetic compatibility test technology, in particular to a static discharge pulse suppression device for electromagnetic compatibility detection. BACKGROUND

[0002] The purpose of electromagnetic compatibility test is to examine whether the system and device can work normally and do not interfere with each other in a specific electromagnetic environment. The static discharge immunity test is one of the key items of electromagnetic compatibility test, which mainly examines whether the device can meet the expected performance requirements and safety requirements under the condition of external static discharge pulse interference.

[0003] In recent years, the intelligent networking degree of motor vehicles is rapidly improving, and the integration level of the system is also correspondingly improved, and the electromagnetic compatibility safety problem is becoming more and more prominent. Especially from the electromagnetic interference such as static discharge pulse, the coupling forms have direct coupling and indirect coupling. Multifunction and high integration have brought troubles to electromagnetic compatibility safety detection and performance determination, such as multifunctional intelligent network terminal, vehicle-mounted integrated entertainment system, etc. Especially how to accurately determine the performance of a certain module in the system. According to the specification requirements of the quality management system, the test sample needs to be connected with the auxiliary equipment to perfect the related function configuration, so that the intelligent network terminal is in a typical working state. In the static discharge test, the product function fails or the performance is degraded, and it cannot be determined whether the sample fails or the auxiliary equipment fails, which leads to that the anti-static interference performance of the test sample cannot be given a scientific and accurate determination. Therefore, in the static discharge test, an intermediate module needs to be introduced to realize the performance "distinguishing" of the test sample and the auxiliary equipment.

[0004] The current static discharge pulse protection measures will cause the product function to fail or the performance to degrade. 1. Interrupt the connection to realize the protection of the product and the auxiliary equipment; 2. Sacrifice part of the product performance for protection. When facing higher safety requirements, the importance of the device with such "distinguishing ability" is more and more prominent. SUMMARY

[0005] In view of the above problems, a static discharge pulse suppression device for electromagnetic compatibility detection is proposed.

[0006] The technical scheme of the present application is: an electrostatic discharge pulse suppression device for electromagnetic compatibility detection, comprising a shielding packaging shell, an electrostatic discharge pulse suppression circuit board in the shielding packaging shell, and an A port and a B port at two ends of the shielding packaging shell, the A port and the B port each comprising a 2-wire port, an 8-wire Ethernet port and a vehicle-mounted Ethernet port connected with each other, and the electrostatic discharge pulse suppression circuit board being sequentially connected with an A-end overvoltage protection unit, an A-end first-stage pulse suppression unit, an A-end second-stage pulse suppression unit, an A-end filter decoupling unit, a B-end filter decoupling unit, a B-end second-stage pulse suppression unit, a B-end first-stage pulse suppression unit and a B-end overvoltage protection unit, the A port being an input end of the A-end overvoltage protection unit, the B port being an input end of the B-end overvoltage protection unit, and the shielding packaging shell being grounded.

[0007] Preferably, the port and the shielding packaging shell are installed in a mode of installing a waveguide on the shell, wherein the ratio of the depth of the waveguide to the circumference of the inner diameter of the waveguide is between 3 and 5, a detachable threaded shielding cap is installed outside the waveguide, the shielding cap is screwed on the waveguide when not in use, and the threaded shielding cap is opened when in use, an insulating sleeve is added outside the threaded shielding cap to avoid electrostatic interference caused by external contact.

[0008] Preferably, the connection part of the waveguide and the shell of the shielding packaging shell is a low-impedance interface.

[0009] Preferably, the low-impedance interface is that the connection surfaces are uniformly plated with tin with a thickness of the order of um, and a low-impedance conductive gasket is additionally added, the fastening pressure at the connection is greater than 15 MPa, and the transferred impedance is lower than 2 mΩ.

[0010] Preferably, the A port is formed by selecting the port by a plug-in switch on the A-end overvoltage protection unit, and the B port is formed by selecting the port by a plug-in switch on the B-end overvoltage protection unit.

[0011] Preferably, the A-end overvoltage protection unit and the B-end overvoltage protection unit: a pulse voltage coupled from a signal line is added to a micro-signal relay coil loop, a micro-signal relay coil power supply is automatically short-circuited to ground under impedance conditions, the micro-signal relay coil voltage is controlled in this way, and overvoltage on-off protection control of the input signal is realized.

[0012] Preferably, the A-end overvoltage protection unit and the B-end overvoltage protection unit have the same circuit, each input corresponding overvoltage protection circuit comprises a self-restoring fuse connected in series with a signal input end, a micro-signal relay of an overvoltage protection execution unit, a direct-current power supply switch controlled by the micro-signal relay coil, a pulse suppression diode for detecting the relay coupled voltage, an impedance resistor and a battery-powered direct-current source; wherein the signal micro-signal relay satisfies the test communication rate requirement, and the insertion loss is less than 0.05 dB.

[0013] Preferably, the A-end first-stage pulse suppression unit and the B-end first-stage pulse suppression unit circuit are the same, and each input corresponding signal stage TVS tube is used, the TVS tube meets the test communication rate requirement, and the insertion loss is less than 0.1 dB.

[0014] Preferably, the A-end filter decoupling unit and the B-end filter decoupling unit circuit are the same, and each input signal corresponding filter decoupling circuit comprises a signal line filter, an input end capacitor and a resistor of the signal line filter, and a filter inductance at the output end of the signal line filter, the other end of the filter inductance is away from the signal line filter and is connected with a bidirectional TVS tube, so as to balance the voltage difference of the pulse on the balanced differential mode wire harness; wherein the response time of the bidirectional TVS tube is ps level, the clamping voltage is lower than 10V; the accuracy of the input end capacitor and the resistor is better than 1‰, and the accuracy of the output end filter inductance is better than 1%.

[0015] Preferably, the signal line filter is integrated by common mode and differential mode circuits, or a communication signal transformer is selected.

[0016] Preferably, the shielding packaging shell is composed of a lower rectangular shell and an upper packaging cover plate, the electrostatic discharge pulse suppression circuit board is fixedly installed in the lower rectangular shell, the packaging cover plate is fixedly packaged by screws, and a tin layer with a thickness of um level is plated on the connection part of the packaging cover plate and the lower rectangular shell, and a metal braided gasket is further added, so as to obtain low impedance.

[0017] Preferably, the thickness of the metal shell of the shielding packaging shell is more than 6 times of the skin depth of the material.

[0018] Preferably, an insulating medium or insulating paint is applied to all surfaces of the metal shell except the grounding position and the operable surface, so as to realize an insulating impedance greater than 1MΩ.

[0019] Preferably, the device is connected between a test sample and auxiliary equipment, and electrostatic discharge pulses entering from any end are shielded.

[0020] The electrostatic discharge pulse suppression device for electromagnetic compatibility detection of the present application has the advantages that the device can realize uninterrupted communication connection in the electrostatic discharge pulse suppression process, can determine and identify the electrostatic protection performance of a single unit in the system, and has strong port versatility, thereby greatly improving the applicability of electromagnetic compatibility tests. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The structure block diagram of the electrostatic discharge pulse suppression device for electromagnetic compatibility detection of the present application is shown in the figure.

[0022] Figure 2 The schematic diagram of the embodiment of the present application is shown in the figure.

[0023] Figure 3AThe schematic diagram of the A part circuit in the electrostatic discharge pulse suppression circuit of the application;

[0024] Figure 3B The schematic diagram of the B part circuit in the electrostatic discharge pulse suppression circuit of the application;

[0025] Figure 4 The schematic diagram of the internal structure of the pulse suppression device of the application;

[0026] Figure 5 The performance verification diagram of the pulse suppression device of the application;

[0027] Figure 6A The result diagram of the device of the application after suppressing the +10kV electrostatic pulse;

[0028] Figure 6B The result diagram of the device of the application after suppressing the -10kV electrostatic pulse. DETAILED DESCRIPTION

[0029] The application will be described in detail below with reference to the drawings and specific embodiments. The embodiments are implemented on the premise of the technical solution of the application, and detailed implementation modes and specific operation processes are given, but the protection scope of the application is not limited to the following embodiments.

[0030] I. Embodiment 1

[0031] As shown in Figure 1 The structural block diagram of the electrostatic discharge pulse suppression device for electromagnetic compatibility detection includes the 2-wire port 1 of the A end, the 8-wire Ethernet port 2, the vehicle-mounted Ethernet port 3, the A-end overvoltage protection unit 4 of the A-end protection unit, the A-end first-stage pulse suppression unit 5, the A-end second-stage pulse suppression unit 6, and the A-end filter decoupling unit 7, the B-end filter decoupling unit 8 of the B-end protection unit, the B-end second-stage pulse suppression unit 9, the B-end first-stage pulse suppression unit 10, and the B-end overvoltage protection unit 11, the 2-wire interface port 12 of the B end, the 8-wire Ethernet port 13, the vehicle-mounted Ethernet interface 14, and the shielding packaging shell 15, the shielding packaging shell 15 is grounded, and the shielding packaging shell grounding point 16.

[0032] As shown in Figure 2 According to the quality management system, the test sample is connected to the 8-wire Ethernet port 2 of the A end of the device, and the auxiliary equipment is connected to the 8-wire Ethernet port 13 of the B end of the device.

[0033] 1. Place the entire system on the test bench, and use an insulating support with a thickness of 50 mm (the dielectric constant of the support material is less than 1.4) for the connection line. The electrostatic discharge pulse suppression device for electromagnetic compatibility detection is connected to the reference ground plane.

[0034] 2、The test sample is subjected to contact discharge and air discharge, and the test sample and the auxiliary equipment can normally communicate, and the connection is not interrupted.

[0035] 3、The oscilloscope and voltage probe are used to collect pulse voltage at the A port and B port of the electrostatic discharge pulse suppression device for electromagnetic compatibility detection. At this time, the A port is the input end, and the B port is the output end. The high-amplitude voltage pulse can be collected on the connection line of the A port; while no obvious pulse voltage can be collected at the B port (for example, if the test sample is directly grounded, low-amplitude pulses and stray pulses coupled from the reference ground plane and transmitted to the connection line by the auxiliary equipment can be collected). When the connection line of the output B port is disconnected, no obvious pulse voltage can be collected at the output B port of the electrostatic discharge pulse suppression device for electromagnetic compatibility detection.

[0036] 4、Conversely, the auxiliary equipment is subjected to contact discharge and air discharge. Within the equipment electrostatic protection performance index, the test sample and the auxiliary equipment can normally communicate, and the connection is not interrupted.

[0037] 5、The oscilloscope and voltage probe are used to collect pulse voltage at the A port and B port of the pulse suppression device. At this time, the B port is the input end, and the A port is the output end. The high-amplitude pulse voltage can be collected on the connection line of the B port; while no obvious high-amplitude pulse voltage can be collected at the A port (for example, if the auxiliary equipment is directly grounded, low-amplitude pulses and stray pulses coupled from the reference ground plane and transmitted to the connection line by the test sample can be collected at the A port). When the connection line of the A port is disconnected, no obvious pulse voltage can be collected at the A port of the pulse suppression device.

[0038] 6、For contact discharge to the reference ground plane, the test sample and the auxiliary equipment will both generate low-amplitude pulses and stray pulses due to field coupling. When the connection line of the A port is disconnected, no low-amplitude pulses and stray pulses coupled by the auxiliary equipment, transmitted to the pulse suppression device A port through the connection line and the pulse suppression device B port can be collected at the pulse suppression device A port; while when the connection line of the B port is disconnected, no voltage pulse coupled by the test sample, transmitted to the pulse suppression device B through the connection line and the pulse suppression device A can be collected at the pulse suppression device B.

[0039] The electrostatic discharge pulse suppression device for electromagnetic compatibility detection is connected between the test sample and the auxiliary equipment, to ensure that the test sample and the auxiliary equipment normally communicate during the test. By selecting the continuous mode, it is ensured that the test sample or the auxiliary equipment is tested alone without interference.

[0040] II. Embodiment 2

[0041] 1、See Figure 2The device performance is checked. The static electricity discharge is directly contacted on the port 2 line port of the device A, and the voltage is collected on the port of the device B to verify the performance of the device.

[0042] 2. The test voltage level 1 is applied on the port of the device A (any voltage within the rated protection voltage range), and the voltage is collected on the port of the device B, and no obvious pulse voltage can be collected.

[0043] 3. The 3V DC voltage is inputted by using 2 alkaline batteries on the port of the device A, and the 3V voltage can be collected on the port of the device B; if the high-level static electricity discharge pulse (peak value 20kV) is applied on the port of the device A, the 3V voltage cannot be collected on the port of the device B; after the static electricity interference stops applying, the 3V output voltage can be collected on the port of the device B.

[0044] The function test is realized before, during and after the static electricity interference.

[0045] Three, embodiment 3

[0046] 1. The interface 2 line input port 1, the 8 line Ethernet input port 2, the vehicle-mounted Ethernet input port 3 are realized by installing the waveguide on the shell, wherein the ratio of the depth of the waveguide to the circumference of the inner diameter is greater than 3, and the ratio is between 3 and 5. The detachable threaded shielding cap is installed outside the waveguide, and the shielding cap can be screwed on the waveguide when not in use, and opened when in use. An insulating sleeve is added outside the threaded shielding cap to avoid static electricity interference caused by external contact.

[0047] 2. The 2 line interface output port 12, the 8 line Ethernet output port 13, the vehicle-mounted Ethernet output interface 14 are realized by installing the waveguide on the shell, wherein the ratio of the depth of the waveguide to the circumference of the inner diameter is greater than 3, and the ratio is between 3 and 5. The detachable threaded shielding cap is installed outside the waveguide, and the shielding cap can be screwed on the waveguide when not in use, and opened when in use. An insulating sleeve is added outside the threaded shielding cap to avoid static electricity interference caused by external contact.

[0048] 3. The connection part of the waveguide and the shielding packaging shell 15 shell adopts a low impedance interface (preferably, the connection surface can be uniformly plated with tin with a thickness of um order of magnitude to realize low transfer impedance), and a low impedance conductive liner is additionally added. The fastening pressure at the connection is greater than 15MPa. Through the above measures, the transfer impedance is lower than 2mΩ.

[0049] 4. As shown in Figure 1 , the A end overvoltage protection unit 4 adopts plug-in switch to select the port 1, 2 and 3 to form the A port; the B end overvoltage protection unit 11 adopts plug-in switch to select the port 12, 13 and 14 to form the B port.

[0050] 5. As shown in Figure 3A ,3B As shown, the pulse suppression circuit includes A-end overvoltage protection unit A1 and B-end overvoltage protection unit B1, A-end first-stage pulse suppression unit A2 and B-end first-stage pulse suppression unit B2. A-end filter decoupling unit A3 and B-end filter decoupling unit B3. C is a second-stage pulse suppression unit shared by A-end and B-end. Wherein the A-end and B-end circuits are symmetrical, and are respectively for suppressing voltage pulses from both ends. C realizes lower micro-pulse suppression and reduces the differential mode voltage between the pair of lines.

[0051] 6, I1 and I2 are a group of signal lines, I3 and I4 are a group of signal lines, which together realize Ethernet 100M signal communication. The working principles of the two groups of pair lines are the same.

[0052] 7, A-end overvoltage protection unit and B-end overvoltage protection unit, as shown in A1 and B1 parts in Figure 3A , 3B The self-recovery fuse F1-F8 (Note: for larger current or power limit) connected in series with the signal input end, the micro-signal relay K1-K4 of the overvoltage protection execution unit, the DC power switch SW1-SW4 controlled by the micro-signal relay coil conduction, the pulse suppression diode U1-U4 for detecting the relay coupled voltage, the resistor R5-R24, and the battery-powered DC source and wire loop, etc.

[0053] Take the voltage protection of terminal I1 and I2 of A end as an example, terminal I1 is connected to self-recovery fuse F1 and linked to signal relay K1 pin 6. When the relay is powered on, pin 6 and pin 5 are conductive, output to the next stage circuit, otherwise through resistance R7 to reference ground. Similarly, terminal I2 is connected to self-recovery fuse F2 and linked to signal relay K1 pin 3. When the relay is powered on, pin 3 and pin 4 are conductive, output to the next stage circuit, otherwise through resistance R8 to reference ground. The power supply of the relay is connected to resistance R4 by SW1 of the battery-powered DC source, and is divided into two branches. One branch passes through R5 to connect the voltage input pin 1 of the relay K1 coil, and the output pin 8 outputs to the negative electrode of the power supply (which can also be the reference ground) through R6. The other branch is connected to the reference ground through the pulse suppression diode U1. The wire between R4 and U1 is a coupling loop (linear coupling or loop coupling can be used, loop coupling is used in this embodiment, and the length ratio or loop area ratio needs to be adjusted), which couples the voltage from the wires between F1, F2 and the relay. (In the PCB, the interference wire and the coupling wire need to be made in separate layers, maintaining a certain length ratio, which can be selected in the range of 3:1 to 50:1, and the inductive coupling is achieved by using a ring-shaped PCB printed wire, and the loop area ratio can be preferably 3:1 to 100:1. The specific value can be adjusted according to the applicable overvoltage protection level, circuit board implementation process and component parameters. In this embodiment, 50:1 is used. In the process of making a printed circuit board, a copper-clad process with a thickness of 2-5 ounces is used to isolate the layers). When any one or both of the pair of wires I1 and I2 input an interference voltage, the coupling voltage of the relay coupling loop reaches the rated value, the pulse suppression diode U1 is turned on, the voltage difference between the two ends of the micro-signal relay K1 coil is reduced, which is not enough to maintain the working state of the micro-signal relay K1, and the relay coil loses power, thereby achieving the protection function. After the pulse interference disappears, the relay K1 coil is restored to power, the relay K1 contact is normally closed, and the signals input from terminals I1 and I2 can be normally output to the D1 port of the B1 unit. If any one or both of terminals I1 and I2 exceeds a certain voltage interference (set to 15kV or more in this embodiment), the relay automatically opens. Similarly, the overvoltage protection of terminals I3 and I4 of A end, terminals I1 and I2 of B end, and terminals I3 and I4 of B end is implemented as described above.

[0054] Wherein the signal micro-signal relay needs to meet the test communication rate requirement, and the insertion loss is less than 0.05dB.

[0055] 8、In the first stage pulse suppression unit of this embodiment, a signal level TVS array D1, D2, D3, D4 is applied. The corresponding time is ps level, such as Figure 3A , 3BAs shown in sections A2 and B2. A second-stage pulse suppression unit can be added as needed to achieve a combination of high and low voltage pulse suppression. The second-stage pulse suppression unit can be placed between the first-stage pulse suppression unit and the filter / decoupling circuit, or between the filter / decoupling circuits at terminals A and B, mainly considering the residual voltage and spatial coupling effect of the voltage pulse from the previous stage on other circuits. In this implementation, the second-stage pulse suppression unit is placed between the filter / decoupling circuits at terminals A and B, and consists of low-clamp voltage pulse suppression diodes D5 and D6.

[0056] The high-speed signal TVS diode (pulse suppression diode) array integrated components need to meet the test communication rate requirements and have an insertion loss of less than 0.1dB.

[0057] 9. For example Figure 3A , 3B A3 and B3 are symmetrical filtering and decoupling units, consisting of network filters T1 and T2, output filter inductors L1-L8, capacitors C1-C8, and resistors R1-R4. Capacitors C1-C8 and resistors R1-R4 primarily maintain circuit impedance stability. The precision of electronic components such as resistors and capacitors is better than 1‰, and the precision of other components is better than 1%.

[0058] 10. After filtering and decoupling by the network port filter T1, filter inductors L1 and L2, the residual voltage is below a certain level, which is below 100V in this implementation. Due to electrostatic pulse field coupling and other reasons, there may be a certain differential-mode voltage between L1 and L2, affecting communication. D5 and D6 quickly turn on the differential-mode pulse voltage to reduce the voltage difference. D5 and D6 serve as the second stage of pulse voltage suppression.

[0059] 11. See the schematic diagram of the internal structure of the device. Figure 4 The circuit board is connected to signal ports A and B at both ends. The shielding package 15 is composed of a lower rectangular shell and an upper package cover. After the circuit board is fixedly installed in the lower shell, the cover is fixed with screws and finally packaged. The cross section of the cover is tightly connected to the lower shell. The connection point (the seam of the shielding shell cover) is plated with a tin layer with a thickness of μm and a metal braided gasket is added to obtain a lower contact resistance.

[0060] 12. The thickness of the outer shell is more than 6 times the skin depth of the metal material used.

[0061] 13. Except for the grounding location and operable surfaces, all other surfaces of the metal casing are coated with an insulating medium or an insulating varnish to achieve an insulation resistance greater than 1MΩ.

[0062] The entire electrostatic discharge pulse suppression device for electromagnetic compatibility testing is designed to ensure that normal signals can pass through while preventing pulse interference signals from overflowing.

[0063] Four, embodiment 4

[0064] 1. According to the test requirements of the quality management system, the temperature of the test environment in the shielded room is kept at (23±2) DEG C, and the humidity is kept in the range of (36-38) %. The performance of the pulse suppression device is verified according to the scheme shown in the figure. Figure 5

[0065] 2. The pulse suppression module is placed on the test table, supported by insulation, and the grounding end is connected to the metal grounding plane of the test table.

[0066] 3. One end of the pulse suppression module is connected to the discharge test point through a cable, and the length of the cable is greater than 60 cm (the purpose is to avoid the influence of the strong magnetic field and the static pulse field generated by the static generator during charging and discharging). The other end of the pulse suppression module is connected to the oscilloscope port outside the shielded room through the N-type connector fixedly installed on the wall surface of the shielded room.

[0067] 4. The performance of the pulse suppression module is verified under the condition of direct contact by using a 330pF / 330Ω discharge module.

[0068] A contact discharge of ±10kV is applied at the discharge point. The oscilloscope collects the voltage waveform after pulse suppression by edge triggering. As shown in the figures, the maximum value of the positive pulse is +85V, and the maximum value of the negative pulse is -41V. Figure 6A 6B The maximum value of the positive pulse is +38.8V, and the maximum value of the negative pulse is -75.6V. Figure 6A Figure 6B

[0069] 5. The oscilloscope and the pulse suppression device can also be placed in a Faraday cage, and the verification can be performed at the test point outside the Faraday cage.

[0070] The electrostatic discharge pulse suppression device for electromagnetic compatibility detection of the application comprises:

[0071] 1. Under certain test level conditions, the communication connection can be maintained uninterrupted during the electrostatic discharge pulse suppression process.

[0072] 2. Under certain test level conditions, the electrostatic protection performance of a single unit in the system can be determined and distinguished.

[0073] 3. The communication delay increment caused by the 100MHz Ethernet communication process is less than 1ms.

[0074] 4. The communication packet loss rate caused by the 100MHz Ethernet communication process is less than 1 ‰. ​​​​

[0075] 5. It can effectively improve the certification level of electrostatic protection performance for individual units.

[0076] 6. Electrostatic discharge pulse suppression can be performed simultaneously at both the input (A) and output (B) terminals.

[0077] 7. The input terminal (A terminal) and the output terminal (B terminal) are symmetrical and can be used interchangeably.

[0078] 8. It can be used with a variety of ports, including 2-wire analog and digital ports, 8-wire Ethernet ports, and automotive Ethernet ports.

[0079] 9. The device itself has a shielding effectiveness of over 50dB against external electromagnetic fields.

[0080] 10. The transfer impedance of the device joints (an indicator that affects shielding effectiveness through the joint connection) is less than 2mΩ.

[0081] 11. The ratio of the depth to the inner diameter circumference of the waveguide at the interface is greater than 2, preferably 3 to 5.

[0082] 12. The impedance of the grounding wire of the device casing is less than 1mΩ.

[0083] 13. The insulation resistance of the device surface (except for the grounding installation position and the shielding interface position) is greater than 1MΩ, which can effectively prevent external electrostatic pulse interference from affecting the inside of the device.

[0084] 14. The residual voltage after the electrostatic pulse within 10kV is suppressed is less than 100V.

[0085] 15. Under certain test conditions (e.g., 15kV), automatic disconnection can be achieved for protection. The protection level can also be adjusted by regulating component parameters according to protection requirements.

[0086] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An electrostatic discharge pulse suppression device for electromagnetic compatibility testing, characterized in that, The device includes a shielded enclosure, an electrostatic discharge pulse suppression circuit board inside the shielded enclosure, and ports A and B at both ends of the shielded enclosure. Ports A and B each include interconnected 2-wire ports, 8-wire Ethernet ports, and automotive Ethernet ports. The electrostatic discharge pulse suppression circuit board is sequentially connected to an A-end overvoltage protection unit, an A-end first-stage pulse suppression unit, an A-end second-stage pulse suppression unit, an A-end filtering and decoupling unit, a B-end filtering and decoupling unit, a B-end second-stage pulse suppression unit, a B-end first-stage pulse suppression unit, and a B-end overvoltage protection unit. Port A is the input terminal of the A-end overvoltage protection unit, and port B is the input terminal of the B-end overvoltage protection unit. The shielded enclosure is grounded. The port and shielding enclosure are installed by mounting a waveguide on the enclosure. The ratio of the waveguide depth to the inner diameter circumference is between 3 and 5. A removable threaded shielding cap is installed on the outside of the waveguide. When not in use, the shielding cap is screwed onto the waveguide. When in use, it is opened. An insulating sleeve is added to the outside of the threaded shielding cap to avoid electrostatic interference caused by external contact. The connection between the waveguide and the shielded encapsulation shell is a low-impedance interface. The low-impedance interface is formed by uniformly plating a tin layer with a thickness on the order of μm on the connection surface, with an additional low-impedance conductive pad. The fastening pressure at the connection point is greater than 15 MPa, achieving a transfer impedance of less than 2 mΩ.

2. The electrostatic discharge pulse suppression device for electromagnetic compatibility testing according to claim 1, characterized in that, The overvoltage protection unit at end A uses a pluggable switch to select the port, forming port A; the overvoltage protection unit at end B uses a pluggable switch to select the port, forming port B.

3. The electrostatic discharge pulse suppression device for electromagnetic compatibility testing according to claim 2, characterized in that, The A-end overvoltage protection unit and the B-end overvoltage protection unit: use a pulse voltage coupled from the signal line to be added to the micro-signal relay coil circuit, and the power supply of the micro-signal relay coil is automatically short-circuited to ground under impedance conditions to control the voltage across the micro-signal relay coil, thereby realizing overvoltage protection control of the input signal.

4. The electrostatic discharge pulse suppression device for electromagnetic compatibility testing according to claim 3, characterized in that, The A-end overvoltage protection unit and the B-end overvoltage protection unit have the same circuit. The overvoltage protection circuit corresponding to each input includes a self-resetting fuse connected in series at the signal input terminal, a micro-signal relay of the overvoltage protection execution unit, a DC power switch controlled by the conduction of the micro-signal relay coil, a pulse suppression diode for detecting the relay coupling voltage, an impedance resistor, and a battery-powered DC source. The signal micro-signal relay meets the test communication rate requirements, with an insertion loss of less than 0.05dB.

5. The electrostatic discharge pulse suppression device for electromagnetic compatibility testing according to claim 2, characterized in that, The first-stage pulse suppression unit at end A and the first-stage pulse suppression unit at end B have the same circuit, including a TVS transistor for each input. The TVS transistor meets the test communication rate requirements and the insertion loss is less than 0.1dB.

6. The electrostatic discharge pulse suppression device for electromagnetic compatibility testing according to claim 2, characterized in that, The A-end filtering and decoupling unit and the B-end filtering and decoupling unit have the same circuit. The filtering and decoupling circuit corresponding to each input signal includes a signal line filter, a capacitor and resistor at the input end of the signal line filter, and a filter inductor at the output end of the signal line filter. The other end of the filter inductor away from the signal line filter is connected to a bidirectional TVS diode to balance the voltage difference of the pulse on the differential mode harness. The response time of the bidirectional TVS diode is in the ps range, and the clamping voltage is less than 10V. The accuracy of the input capacitor and resistor is better than 1‰, and the accuracy of the output filter inductor is better than 1%.

7. The electrostatic discharge pulse suppression device for electromagnetic compatibility testing according to claim 6, characterized in that, The signal line filter is integrated with common-mode and differential-mode circuits, or a communication signal transformer can be selected.

8. The electrostatic discharge pulse suppression device for electromagnetic compatibility testing according to claim 1, characterized in that, The shielding enclosure consists of a lower rectangular shell and an upper enclosure cover. The electrostatic discharge pulse suppression circuit board is fixedly installed inside the lower rectangular shell. The enclosure cover is fixed and encapsulated with screws. The connection between the enclosure cover and the lower rectangular shell is plated with a tin layer with a cross-sectional thickness of μm and a metal braided gasket is added to obtain low impedance.

9. The electrostatic discharge pulse suppression device for electromagnetic compatibility testing according to claim 8, characterized in that, The thickness of the metal outer shell of the shielding encapsulation shell is more than 6 times the skin depth of the material.

10. The electrostatic discharge pulse suppression device for electromagnetic compatibility testing according to claim 9, characterized in that, Except for the grounding location and operable surfaces, all other surfaces of the metal casing are coated with an insulating medium or an insulating varnish to achieve an insulation resistance greater than 1 MΩ.

11. The electrostatic discharge pulse suppression device for electromagnetic compatibility testing according to any one of claims 3 to 10, characterized in that, The device is connected between the test sample and the auxiliary equipment, shielding against electrostatic discharge pulses entering from either end.

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