Coaxial transmission line structure, fast damped oscillation wave test system and test method

Abstract

The invention relates to a coaxial transmission line structure, a fast damped oscillation wave test system and a test method, and belongs to the field of fast damped oscillation wave testing. A coaxial transmission line whose two ends can be directly connected to a tested port and an oscilloscope is used for processing and design, a fracture is added to an inner conductor of the coaxial transmission line, a metal disc is connected to the fracture, and an insulating material is filled between the metal discs to realize high-fold attenuation of voltage when conducting a fast damped oscillation wave. For a fast damped oscillation wave of a single frequency point, after attenuation by a high-transformation ratio coaxial transmission line, only the signal amplitude is changed, and its waveform characteristics are not changed. Therefore, the actual waveform can be obtained by restoring the amplitude by using the attenuation ratio at the corresponding frequency point after testing, thereby greatly improving the measurement accuracy.

Description

Technical Field

[0001] The present invention relates to the field of fast damped oscillatory wave testing, and in particular to a coaxial transmission line structure, a fast damped oscillatory wave testing system and a testing method. Background Art

[0002] In recent years, the application technology of electronic transformers has become increasingly mature. Its advantages of small size, low power consumption, high precision, and energy-saving and environmentally friendly manufacturing process have made the integration of primary and secondary equipment in the distribution network a trend of standardized and integrated development of distribution equipment. The measured results show that the primary and secondary integrated standardized pole-mounted switch will generate strong electromagnetic interference at the moment of switch operation, which is transmitted to the secondary side through the cable to couple a fast damped oscillation wave with a frequency between several MHz and 45MHz and an amplitude of up to 4 kilovolts. These fast damped oscillation wave signals are random and cannot be predicted by simulation software. They must be determined by actual measurement. Therefore, in order to study the influence of electromagnetic interference on the secondary equipment in the primary and secondary integrated switch equipment, it is necessary to conduct switch operation electromagnetic interference test on the primary and secondary integrated switch equipment of the distribution network.

[0003] When measuring the transient interference voltage generated by switch operation at the port of the secondary device on site, it is often necessary to use a measurement system consisting of a high-voltage probe, a coaxial transmission line, and an oscilloscope. Connect the front end of the primary side of the high-voltage probe to the signal port to be measured, and connect the secondary side of the high-voltage probe to the oscilloscope through a coaxial transmission line, where the coaxial transmission line is generally only used for conduction. The input impedance of the currently commonly used commercial high-voltage probes will change with frequency, resulting in an unstable transformation ratio, and the range will decrease with the increase of frequency. The range of general commercial high-voltage probes at a frequency of 100MHz is below 300V, while the electromagnetic interference voltage may be as high as several thousand volts, which is much higher than the range of the high-voltage probe. Actual measurements show that when the signal strength of the measured standard fast damped oscillation wave is higher than the range of the commercial high-voltage probe, the measurement error is large and the accuracy is too low.

[0004] Secondly, when using a high-voltage probe to test the signal under test, the front end of the probe is often directly exposed to the air, which is easy to introduce other electromagnetic interference signals in the space. In addition, the lead length exposed to the electromagnetic field environment in the space during the test is also long, which increases the amount of interference introduced by the coupling effect of the electromagnetic field in the space on the lead. Summary of the invention

[0005] The object of the present invention is to provide a coaxial transmission line structure, a fast damped oscillation wave test system and a test method to achieve high voltage attenuation and improve measurement accuracy.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A coaxial transmission line structure, comprising: a coaxial transmission line, an insulating material and two metal discs;

[0008] A break is formed on the inner conductor of the coaxial transmission line, two ends of the inner conductor formed at the break are connected to each other with a metal disc, and an insulating material is filled between the two metal discs;

[0009] The two metal discs and the insulating material together form a flat plate capacitor, which is used to attenuate signal strength.

[0010] Optionally, the coaxial transmission line includes: an inner conductor, an insulating layer and a shielding layer arranged in sequence from inside to outside.

[0011] A fast damped oscillatory wave test system, the system comprising: an oscilloscope and the aforementioned coaxial transmission line structure;

[0012] One end of the coaxial transmission line structure is connected to the signal port of the fast damped oscillation wave to be measured, and the other end of the coaxial transmission line structure is connected to the input port of the oscilloscope;

[0013] The coaxial transmission line structure is used to transmit the voltage of the fast damped oscillation wave to be measured to an oscilloscope for display after the voltage is attenuated.

[0014] A fast damped oscillatory wave test method, the method is applied to the aforementioned fast damped oscillatory wave test system, the method comprising:

[0015] According to the signal strength of the fast damped oscillation wave to be measured, a coaxial transmission line structure corresponding to the required attenuation multiple is selected;

[0016] Connect the selected coaxial transmission line structure to the signal port of the fast damped oscillation wave to be measured and the input port of the oscilloscope, and measure and obtain the voltage waveform of the fast damped oscillation wave to be measured;

[0017] According to the voltage waveform, the oscillation frequency of the fast damped oscillation wave to be measured is obtained;

[0018] According to the oscillation frequency, by searching a frequency and scattering parameter correspondence table, a scattering parameter corresponding to the coaxial transmission line at the oscillation frequency is obtained;

[0019] The actual voltage value of the fast damped oscillation wave to be measured is calculated according to the voltage waveform and the corresponding scattering parameter at the oscillation frequency.

[0020] Optionally, selecting a coaxial transmission line structure corresponding to a required attenuation multiple according to the signal strength of the fast damped oscillation wave to be measured specifically includes:

[0021] According to the voltage range of the fast damped oscillation wave to be measured, the voltage range after attenuation of the fast damped oscillation wave to be measured is within the range of the oscilloscope, and the required voltage attenuation multiple is calculated;

[0022] According to the required voltage attenuation times, use the formula Calculate the target value of the scattering parameter S2′1; where R represents the required attenuation factor of the voltage;

[0023] A coaxial transmission line structure with a scattering parameter being a scattering parameter target value S2′1 is selected.

[0024] Optionally, obtaining the oscillation frequency of the fast damped oscillation wave to be measured according to the voltage waveform specifically includes:

[0025] The oscillation frequency of the fast damped oscillation wave to be measured is determined by taking the inverse of the time difference between adjacent wave peaks in the voltage waveform or performing Fourier transform on the voltage waveform data.

[0026] Optionally, the method for determining the frequency and scattering parameter correspondence table is:

[0027] Connect the two ends of the coaxial transmission line structure to the input port and output port of the network analyzer respectively;

[0028] Using a network analyzer to measure the scattering parameters of the coaxial transmission line structure at each frequency within a preset frequency band;

[0029] Each frequency and the scattering parameters at each frequency form a frequency-scattering parameter correspondence table.

[0030] Optionally, the method for determining the frequency and scattering parameter correspondence table is:

[0031] Establish a simulation model for the selected coaxial transmission line structure;

[0032] Performing full-wave simulation using the simulation model to obtain scattering parameters of the selected coaxial transmission line structure at each frequency within a preset frequency band;

[0033] Each frequency and the scattering parameters at each frequency form a frequency-scattering parameter correspondence table.

[0034] Optionally, the formula for calculating the actual voltage value of the fast damped oscillatory wave to be measured is:

[0035]

[0036] Among them, U represents the actual value of the voltage of the fast damped oscillation wave to be measured, U0 represents the voltage in the voltage waveform, S 21 represents the scattering parameter corresponding to the oscillation frequency.

[0037] Optionally, the method further includes connecting the selected coaxial transmission line structure to the signal port of the fast damped oscillation wave to be measured and the input port of the oscilloscope, and measuring and obtaining the voltage waveform of the fast damped oscillation wave to be measured, and then:

[0038] If the peak value of the voltage waveform of the measured fast damped oscillation wave is less than the voltage lower limit, the coaxial transmission line structure is adjusted to reduce the attenuation ratio; the adjusting the coaxial transmission line structure to reduce the attenuation ratio includes: reducing the spacing between metal discs, increasing the relative dielectric constant of the insulating material, increasing the cross-sectional area of ​​the metal disc, or reducing the ratio of the inner diameter of the shielding layer to the outer diameter of the inner conductor;

[0039] If the peak of the voltage waveform of the measured fast damped oscillation wave to be measured is greater than the voltage upper limit value, the coaxial transmission line structure is adjusted to increase the attenuation ratio; the adjusting the coaxial transmission line structure to increase the attenuation ratio includes: increasing the spacing between metal discs, reducing the relative dielectric constant of the insulating material, reducing the cross-sectional area of ​​the metal disc, or increasing the ratio of the inner diameter of the shielding layer to the outer diameter of the inner conductor.

[0040] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0041] The invention discloses a coaxial transmission line structure, a fast damped oscillation wave test system and a test method. The coaxial transmission line whose two ends can be directly connected to a port to be tested and an oscilloscope is used for processing and design. A fracture is added to the inner conductor of the coaxial transmission line, metal discs are connected to the fracture, and insulating materials are filled between the metal discs to achieve high-fold attenuation of voltage when conducting a fast damped oscillation wave. For a fast damped oscillation wave of a single frequency point, only the signal amplitude is changed after attenuation by a high-transformation ratio coaxial transmission line, and its waveform characteristics are not changed. Therefore, the actual waveform can be obtained by restoring the amplitude by using the attenuation ratio at the corresponding frequency point after testing, thereby greatly improving the measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0043] Figure 1 A schematic diagram of a coaxial transmission line structure provided by an embodiment of the present invention;

[0044] Figure 2 A flowchart of a fast damped oscillatory wave testing method provided by an embodiment of the present invention;

[0045] Figure 3 A schematic diagram of the scattering parameter amplitude provided in Example 1 of the present invention;

[0046] Figure 4 A schematic diagram of scattering parameter amplitudes provided in Example 2 of the present invention;

[0047] Figure 5A schematic diagram of scattering parameter amplitudes provided in Example 3 of the present invention;

[0048] Figure 6 This is a schematic diagram of the scattering parameter amplitude provided in Example 4 of the present invention. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] The object of the present invention is to provide a coaxial transmission line structure, a fast damped oscillation wave test system and a test method to achieve high voltage attenuation and improve measurement accuracy.

[0051] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] The embodiment of the present invention provides a coaxial transmission line structure for fast damped oscillatory wave testing, such as Figure 1 As shown in FIG. 1 , the coaxial transmission line structure includes: a coaxial transmission line, an insulating material, and two metal discs. A break is opened on the inner conductor of the coaxial transmission line, and the two ends of the inner conductor formed at the break are connected to a metal disc respectively, and the insulating material is filled between the two metal discs. The two metal discs and the insulating material together form a flat plate capacitor, which is used to attenuate the signal strength.

[0053] The coaxial transmission line includes an inner conductor, an insulating layer and a shielding layer which are arranged in sequence from the inside to the outside.

[0054] The capacitance depends on the material and size of the capacitor. Therefore, the material and dimensional parameters of each structure of the product can be changed to meet different attenuation ratio requirements. For example, the fracture length, the cross-sectional area and material of the metal disc, the insulating material between the metal discs, the model of the original coaxial transmission line, etc. can be adjusted.

[0055] In order to solve the problem of exposed front end of high-voltage probe and too long lead wire during measurement, we use coaxial transmission line whose two ends can be directly connected to the port under test and oscilloscope for processing and design. The shielding layer of the coaxial transmission line can shield the electromagnetic interference generated in the space and enhance the anti-interference ability of the measurement system. It is also very small in size and low in cost. In order to achieve high voltage attenuation, a break is added to the inner conductor of the traditional coaxial transmission line to form a capacitor. In order to meet different attenuation ratio requirements, a metal disc is connected to each end of the break and appropriate insulating material is filled between the metal discs to form a capacitor. The structure is as follows: Figure 1 As shown, the capacitance depends on the material and size of each part of the capacitor. Therefore, different attenuation ratios can be obtained by adjusting the length of the fracture, the cross-sectional area and material of the metal disc, the insulating material between the metal discs, the model of the original coaxial transmission line, etc. In practical applications, the metal discs can be made of conductive materials such as copper and aluminum, and the insulating materials can be made of pure dielectric materials such as PVC and epoxy resin. For a single-frequency fast damped oscillation wave, after attenuation by the high-ratio coaxial transmission line, only the signal amplitude is changed, and its waveform characteristics are not changed. Therefore, it is only necessary to restore the amplitude using the attenuation ratio at the corresponding frequency after testing to obtain the actual waveform. This solution greatly improves the measurement accuracy, saves costs, and is simple and easy.

[0056] The present invention provides a break on the inner conductor of the coaxial transmission line, connects metal discs on the break and fills insulating materials between the metal discs to achieve high voltage attenuation when conducting fast damping oscillation waves. The coaxial transmission line structure provided by the present invention is a high transformation ratio coaxial transmission line structure.

[0057] The present invention also provides a fast damped oscillation wave test system, the system comprising: an oscilloscope and the aforementioned coaxial transmission line structure. One end of the coaxial transmission line structure is connected to the signal port of the fast damped oscillation wave to be tested, and the other end of the coaxial transmission line structure is connected to the input port of the oscilloscope; the coaxial transmission line structure is used to transmit the voltage of the fast damped oscillation wave to be tested to the oscilloscope for display after attenuation.

[0058] When measuring the transient interference voltage generated by the switch operation at the port of the secondary device on site, it is often necessary to use a measurement system consisting of a high-voltage probe, a coaxial transmission line and an oscilloscope. The front end of the high-voltage probe is connected to the signal port to be measured, and the secondary side of the high-voltage probe is connected to the oscilloscope through a coaxial transmission line, wherein the coaxial transmission line is generally only used for conduction. At this time, the front end and lead of the high-voltage probe are exposed to a complex electromagnetic environment, and the lead is very long, which is easy to introduce other electromagnetic interference in the space. Secondly, the high-voltage probe is expensive and large in size, which greatly increases the test cost and is not easy to carry. In actual measurements, the two ends of the high-ratio coaxial transmission line of the present invention are directly connected to the port to be measured and the oscilloscope, and the entire structure has no exposed part in the air, and the shielding layer of the coaxial transmission line can shield the electromagnetic interference caused by the space field, and the anti-interference performance is better. In addition, the coaxial transmission line also has the advantages of low cost and small size.

[0059] The input impedance of commercial high-voltage probes will change with frequency, resulting in unstable transformation ratios. The range will decrease with increasing frequency, making the electromagnetic interference voltage at high frequencies often much higher than the range of high-voltage probes. At a frequency of 100MHz, the range of general commercial high-voltage probes is below 300V, while the range of this high-ratio coaxial transmission line can reach several thousand volts at this frequency, which can cover all the electromagnetic interference voltage ranges of fast damped oscillation waves. The range and attenuation ratio of the high-ratio coaxial transmission line can be adjusted by changing the size of the inner conductor, shielding layer, metal disc, and insulating material, and the application range is wider. This high-ratio coaxial transmission line can still have a very high attenuation multiple at high frequencies, and the range can be much higher than that of commercial high-voltage probes, which makes up for the defect of insufficient range of commercial high-voltage probes in the high-frequency band in fast damped oscillation wave testing. This method also has the advantages of simple operation, low cost and high safety, and can be promoted and applied to local equipment measurement scenarios such as substations.

[0060] The present invention also provides a fast damped oscillatory wave testing method, such as Figure 2 As shown, the method is applied to the aforementioned fast damped oscillatory wave test system, and the method comprises the following steps:

[0061] Step S1, selecting a coaxial transmission line structure corresponding to a required attenuation multiple according to the signal strength of the fast damped oscillation wave to be measured.

[0062] The specific selection process is: according to the voltage range of the fast damped oscillation wave to be measured, the voltage range after attenuation of the fast damped oscillation wave to be measured is within the range of the oscilloscope, and the required voltage attenuation multiple is calculated; using the formula Calculate the target value of the scattering parameter S2′1; where R represents the required attenuation multiple of the voltage; select a coaxial transmission line structure whose scattering parameter is the target value of the scattering parameter S2′1. Where U′ represents a voltage value in the voltage range of the fast damped oscillation wave to be measured, and U0′ represents the voltage value after U′ is attenuated.

[0063] For example, if you need to measure a fast damped oscillation wave electromagnetic disturbance signal with a voltage U0 in the range of 500V-4kV, if the voltage U is between 5V-40V after attenuation by 100 times, the attenuated signal strength can be limited within the range of the oscilloscope. According to the scattering parameter calculation formula It can be seen that the scattering parameter S' can be selected at its oscillation frequency 21 It is measured with a high transformation ratio coaxial transmission line of approximately -40dB.

[0064] Step S2, connecting the selected coaxial transmission line structure to the signal port of the fast damped oscillation wave to be measured and the input port of the oscilloscope, and measuring to obtain the voltage waveform of the fast damped oscillation wave to be measured.

[0065] In the fast damped oscillation wave test, the two ends of the high transformation ratio coaxial transmission line selected in step 1 are connected to the signal port to be tested and the input port of the oscilloscope respectively, and the fast damped oscillation wave actual waveform U0 is measured by the oscilloscope.

[0066] Step S3, obtaining the oscillation frequency of the fast damped oscillation wave to be measured according to the voltage waveform.

[0067] There are two ways to obtain the oscillation frequency, and either way can obtain the oscillation frequency of the fast damped oscillation wave to be measured.

[0068] The first method is to directly observe the measured waveform obtained in step S2 and take the inverse of the time difference between adjacent wave peaks to obtain the oscillation frequency of the fast damped oscillation wave.

[0069] The second method is to export the measured waveform data obtained in step S2 and perform Fourier transform on it to obtain the oscillation frequency of the fast damped oscillation wave.

[0070] Step S4, according to the oscillation frequency, by searching a frequency and scattering parameter correspondence table, obtain the scattering parameters corresponding to the coaxial transmission line at the oscillation frequency.

[0071] A graph of the scattering parameters versus frequency can be obtained in one of the following ways:

[0072] The first method is to connect the two ends of the high-ratio coaxial transmission line to the input and output ports of the network analyzer respectively, set the frequency to 1MHz-100MHz, and perform scanning measurement within this frequency band to obtain the scattering parameter S of the high-ratio coaxial transmission line. 21 Amplitude, phase and frequency characteristics.

[0073] The second method is to use a computer to obtain the scattering parameter S through full-wave simulation. 21. Based on the actual data of the high-ratio coaxial transmission line used in the test, a simulation model is established in the simulation software, where the actual data includes the total length of the high-ratio coaxial transmission line, the inner and outer diameters of the shielding layer, the inner and outer diameters of the insulating layer, the outer diameter of the inner conductor, the fracture length, the radius and thickness of the metal disc, etc. In the full-wave simulation software, the shielding layer, the inner conductor and the metal disc medium can be set as ideal conductors (the conductivity is infinite), the insulating material between the coaxial transmission line insulation layer and the metal disc can be set to PVC (polyvinyl chloride), epoxy resin and other materials, and the rest is free space (the real shielding layer, inner conductor and metal disc are all made of high conductivity materials, such as copper, and can be regarded as ideal conductors in the simulation to speed up the simulation; as for the environment in which the high-ratio coaxial transmission line is located, it can be regarded as free space to simplify the problem). The frequency is set to 1MHz-100MHz, and the scattering parameter S of the high-ratio coaxial transmission line in this frequency band is calculated. 21 .

[0074] Step S5, calculating the actual voltage value of the fast damped oscillation wave to be measured according to the voltage waveform and the corresponding scattering parameter at the oscillation frequency.

[0075] Using U0 obtained in step S2 and S obtained in step S4 21 , through the formula The measured results are restored to obtain the actual value of the fast damped oscillation wave.

[0076] If the test result is not ideal (when the attenuation ratio is too high, the voltage after attenuation by the coaxial transmission line is too small. At this time, the measured signal is easily submerged in the noise. When the oscilloscope sensitivity is set low, it may not be triggered. When the sensitivity is set high, it is easy to cause false triggering of the oscilloscope caused by the noise signal, and the waveform cannot be correctly obtained from the oscilloscope; if the attenuation ratio is too low, the voltage after attenuation by the coaxial transmission line is too large, which may exceed the oscilloscope range and the waveform amplitude cannot be obtained), the attenuation ratio can be changed by adjusting the fracture distance and metal disc area of ​​the high transformation ratio coaxial transmission line, reselect the high transformation ratio coaxial transmission line material and size scheme, and repeat the above steps.

[0077] That is, if the peak value of the voltage waveform of the fast damped oscillation wave to be measured is less than the voltage lower limit, the coaxial transmission line structure is adjusted to reduce the attenuation ratio; the adjustment of the coaxial transmission line structure to reduce the attenuation ratio includes: reducing the distance between metal discs, increasing the relative dielectric constant of the insulating material, increasing the cross-sectional area of ​​the metal disc, or reducing the ratio of the inner diameter of the shielding layer to the outer diameter of the inner conductor. If the peak value of the voltage waveform of the fast damped oscillation wave to be measured is greater than the voltage upper limit, the coaxial transmission line structure is adjusted to increase the attenuation ratio; the adjustment of the coaxial transmission line structure to increase the attenuation ratio includes: increasing the distance between metal discs, reducing the relative dielectric constant of the insulating material, reducing the cross-sectional area of ​​the metal disc, or increasing the ratio of the inner diameter of the shielding layer to the outer diameter of the inner conductor.

[0078] Provide high-ratio coaxial transmission line solutions of different sizes and media:

[0079] Example 1

[0080] Size parameters: The total length of the high-ratio coaxial transmission line is 1m (different line lengths can be selected according to actual conditions, without affecting the attenuation ratio), the outer diameter of the inner conductor is 1.29mm, the inner diameter of the insulation layer is 1.29mm, the outer diameter is 4.6mm, the inner diameter of the shielding layer is 4.6mm, the outer diameter is 6.3mm, the fracture length is 1mm, the radius of the metal disc is 1.5mm, and the thickness is 0.5mm.

[0081] Materials: The shielding layer, inner conductor and metal disc materials are all PEC, the insulation layer material is PVC with a relative dielectric constant of 2.3, and the insulation material between the metal discs is epoxy resin with a relative dielectric constant of 3.6.

[0082] The frequency is set to 1MHz-100MHz, and the scattering parameter S of the high-ratio coaxial transmission line in this frequency band is 21 like Figure 3 When the actual amplitude of the measured fast damped oscillation wave is 4kV, it will be attenuated by 77dB, 68dB, 57dB, 47dB, and 36dB at 1MHz, 3MHz, 10MHz, 30MHz, and 100MHz respectively. After attenuation by the high-ratio coaxial transmission line, the voltages correspond to 0.57V, 1.59V, 5.65V, 17.87V, and 63.4V respectively, which are all within the range of a general oscilloscope.

[0083] Example 2

[0084] Size parameters: The total length of the high-ratio coaxial transmission line is 1m (different line lengths can be selected according to actual conditions, without affecting the attenuation ratio), the outer diameter of the inner conductor is 1.29mm, the inner diameter of the insulation layer is 1.29mm, the outer diameter is 4.6mm, the inner diameter of the shielding layer is 4.6mm, the outer diameter is 6.3mm, the fracture length is 2mm, the radius of the metal disc is 1.5mm, and the thickness is 0.5mm.

[0085] Materials: The shielding layer, inner conductor and metal disc materials are all PEC, the insulation layer material is PVC with a relative dielectric constant of 2.3, and the insulation material between the metal discs is epoxy resin with a relative dielectric constant of 3.6.

[0086] The frequency is set to 1MHz-100MHz, and the scattering parameter S of the high-ratio coaxial transmission line in this frequency band is 21 like Figure 4 When the actual amplitude of the measured fast damped oscillation wave is 4kV, it will be attenuated by 86dB, 78dB, 67dB, 56dB and 45dB at 1MHz, 3MHz, 10MHz, 30MHz and 100MHz respectively. After attenuation by the high transformation ratio coaxial transmission line, the voltages correspond to 0.2V, 0.5V, 1.79V, 6.34V and 22.49V respectively, which are all within the range of a general oscilloscope.

[0087] Example 3

[0088] Size parameters: The total length of the high-ratio coaxial transmission line is 1m (different line lengths can be selected according to actual conditions, without affecting the attenuation ratio), the outer diameter of the inner conductor is 1.29mm, the inner diameter of the insulation layer is 1.29mm, the outer diameter is 4.6mm, the inner diameter of the shielding layer is 4.6mm, the outer diameter is 6.3mm, the fracture length is 2mm, the radius of the metal disc is 1.5mm, and the thickness is 0.5mm.

[0089] Materials: The shielding layer, inner conductor and metal disc materials are all PEC, the insulation layer material is PVC with a relative dielectric constant of 2.3, and the insulation material between the metal discs is a pure dielectric material with a relative dielectric constant of 10.

[0090] The frequency is set to 1MHz-100MHz, and the scattering parameter S of the high-ratio coaxial transmission line in this frequency band is 21 like Figure 5 When the actual amplitude of the measured fast damped oscillation wave is 4kV, it will be attenuated by 76dB, 67dB, 56dB, 46dB, and 35dB at 1MHz, 3MHz, 10MHz, 30MHz, and 100MHz respectively. After attenuation by the high-ratio coaxial transmission line, the voltages correspond to 0.63V, 1.79V, 6.34V, 20.05V, and 71.13V respectively, which are all within the range of a general oscilloscope.

[0091] Example 4

[0092] Size parameters: The total length of the high-ratio coaxial transmission line is 1m (different line lengths can be selected according to actual conditions without affecting the attenuation ratio), the outer diameter of the inner conductor is 2.17mm, the inner diameter of the insulation layer is 2.17mm, the outer diameter is 6.15mm, the inner diameter of the shielding layer is 6.15mm, the outer diameter is 8.28mm, the fracture length is 1mm, the radius of the metal disc is 2mm, and the thickness is 0.5mm.

[0093] Materials: The shielding layer, inner conductor and metal disc materials are all PEC, the insulation layer material is PVC with a relative dielectric constant of 2.3, and the insulation material between the metal discs is epoxy resin with a relative dielectric constant of 3.6.

[0094] The frequency is set to 1MHz-100MHz, and the scattering parameter S of the high-ratio coaxial transmission line in this frequency band is 21 like Figure 6 When the actual amplitude of the measured fast damped oscillation wave is 4kV, it will be attenuated by 73dB, 64dB, 54dB, 44dB, and 33dB at 1MHz, 3MHz, 10MHz, 30MHz, and 100MHz respectively. After attenuation by the high-ratio coaxial transmission line, the voltages correspond to 0.9V, 2.52V, 7.98V, 25.24V, and 89.55V respectively, which are all within the range of a general oscilloscope.

[0095] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0096] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A fast damped oscillatory wave test method, characterized in that: The method is applied to a fast damped oscillation wave test system, the system comprising: an oscilloscope and a coaxial transmission line structure; one end of the coaxial transmission line structure is connected to a signal port of a fast damped oscillation wave to be tested, and the other end of the coaxial transmission line structure is connected to an input port of the oscilloscope; the coaxial transmission line structure is used to transmit the voltage of the fast damped oscillation wave to be tested to the oscilloscope for display after attenuation; the coaxial transmission line structure comprises: a coaxial transmission line, an insulating material and two metal discs; a fracture is opened on the inner conductor of the coaxial transmission line, two ends of the inner conductor formed at the fracture are respectively connected to a metal disc, and the insulating material is filled between the two metal discs; the two metal discs and the insulating material together form a flat plate capacitor, and the flat plate capacitor is used to attenuate signal strength; The method comprises: According to the signal strength of the fast damped oscillation wave to be measured, a coaxial transmission line structure corresponding to the required attenuation multiple is selected; Connect the selected coaxial transmission line structure to the signal port of the fast damped oscillation wave to be measured and the input port of the oscilloscope, and measure and obtain the voltage waveform of the fast damped oscillation wave to be measured; According to the voltage waveform, the oscillation frequency of the fast damped oscillation wave to be measured is obtained; According to the oscillation frequency, by searching a frequency and scattering parameter correspondence table, a scattering parameter corresponding to the coaxial transmission line at the oscillation frequency is obtained; Calculating the actual voltage value of the fast damped oscillation wave to be measured according to the voltage waveform and the corresponding scattering parameter at the oscillation frequency; The method further comprises connecting the selected coaxial transmission line structure to the signal port of the fast damped oscillation wave to be measured and the input port of the oscilloscope, and measuring and obtaining the voltage waveform of the fast damped oscillation wave to be measured, and then: If the peak value of the voltage waveform of the measured fast damped oscillation wave is less than the voltage lower limit, the coaxial transmission line structure is adjusted to reduce the attenuation ratio; the adjusting the coaxial transmission line structure to reduce the attenuation ratio includes: reducing the spacing between metal discs, increasing the relative dielectric constant of the insulating material, increasing the cross-sectional area of ​​the metal disc, or reducing the ratio of the inner diameter of the shielding layer to the outer diameter of the inner conductor; If the peak of the voltage waveform of the measured fast damped oscillation wave to be measured is greater than the voltage upper limit value, the coaxial transmission line structure is adjusted to increase the attenuation ratio; the adjusting the coaxial transmission line structure to increase the attenuation ratio includes: increasing the spacing between metal discs, reducing the relative dielectric constant of the insulating material, reducing the cross-sectional area of ​​the metal disc, or increasing the ratio of the inner diameter of the shielding layer to the outer diameter of the inner conductor.

2. The fast damped oscillatory wave testing method according to claim 1, characterized in that: The selecting of the coaxial transmission line structure corresponding to the required attenuation multiple according to the signal strength of the fast damped oscillation wave to be measured specifically includes: According to the voltage range of the fast damped oscillation wave to be measured, the voltage range after attenuation of the fast damped oscillation wave to be measured is within the range of the oscilloscope, and the required voltage attenuation multiple is calculated; According to the required voltage attenuation times, use the formula , calculate the target value of the scattering parameter ; Where R represents the required voltage attenuation multiple; Select the scattering parameter as the scattering parameter target value Coaxial transmission line structure.

3. The fast damped oscillatory wave testing method according to claim 1, characterized in that: According to the voltage waveform, the oscillation frequency of the fast damped oscillation wave to be measured is obtained, specifically including: The oscillation frequency of the fast damped oscillation wave to be measured is determined by taking the inverse of the time difference between adjacent wave peaks in the voltage waveform or performing Fourier transform on the voltage waveform data.

4. The fast damped oscillatory wave testing method according to claim 1, characterized in that: The method for determining the frequency and scattering parameter correspondence table is: Connect the two ends of the coaxial transmission line structure to the input port and output port of the network analyzer respectively; Using a network analyzer to measure the scattering parameters of the coaxial transmission line structure at each frequency within a preset frequency band; Each frequency and the scattering parameters at each frequency form a frequency-scattering parameter correspondence table.

5. The fast damped oscillatory wave testing method according to claim 1, characterized in that: The method for determining the frequency and scattering parameter correspondence table is: Establish a simulation model for the selected coaxial transmission line structure; Performing full-wave simulation using the simulation model to obtain scattering parameters of the selected coaxial transmission line structure at each frequency within a preset frequency band; Each frequency and the scattering parameters at each frequency form a frequency-scattering parameter correspondence table.

6. The fast damped oscillatory wave testing method according to claim 1, characterized in that: The formula for calculating the actual voltage value of the fast damped oscillatory wave to be measured is: Among them, U represents the actual value of the voltage of the fast damped oscillation wave to be measured, U0 represents the voltage in the voltage waveform, S 21 represents the scattering parameter corresponding to the oscillation frequency.

7. The fast damped oscillatory wave testing method according to claim 1, characterized in that: The coaxial transmission line comprises: an inner conductor, an insulating layer and a shielding layer which are arranged in sequence from the inside to the outside.

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