Irregular cable field line coupling modeling method and system based on current injection probe test

Abstract

The invention relates to an irregular cable field line coupling modeling method and system based on a current injection probe test, and the method comprises the steps: configuring a test system after the calibration of a vector network analyzer, determining a test frequency band and a test point, additionally installing a current injection probe at the test point, and connecting the current injection probe with the vector network analyzer, a first S parameter between the injection points is measured respectively, a second S parameter between the probe and the right port of the measured cable is measured when the probe is located at the injection points, the current injection probe is removed, two ports of the vector network analyzer are connected with the two ends of the measured line respectively, and a third S parameter is measured; and constructing a field line coupling effect model according to the obtained first S parameter, the second S parameter and the third S parameter. According to the method, the limitation that traditional analysis / semi-analysis modeling is difficult to adapt to complex conditions is avoided, the huge calculation amount of direct full-wave calculation is avoided, the external field is converted into the equivalent voltage source based on the physical principle, and the relation between the external field and the port coupling value is directly established through testing.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic field testing, and in particular to a method and system for modeling irregular cable field line coupling based on current injection detection testing. Background Art

[0002] With the widespread application of new technologies such as 5G, Internet of Things, and artificial intelligence in society, the electromagnetic environment faced by electronic information systems is becoming increasingly complex, and the electromagnetic compatibility issues caused are increasing, posing challenges to the design, development, and use of electronic information systems. If the electromagnetic environmental effects generated by electronic information systems in the electromagnetic environment are not properly resolved, serious "self-disturbance and mutual interference" problems will occur, affecting the performance of electronic information systems.

[0003] For electronic information systems in the design and development stage, it is the key to understand the boundary of its electromagnetic environment effect, clearly describe the environment in which it can work, what performance it can achieve, and propose its usage boundary. The current electromagnetic compatibility test of electronic information systems, such as GJB 151B-2013, mainly adopts a single signal test, which cannot fully examine the system boundary problem and cannot provide a basis for the electromagnetic environment adaptability of electronic information systems in unknown environments. When cables are exposed to external electromagnetic fields, they will couple external field interference signals and concentrate them at the cable ports to reflect coupling voltage and current, which will have a potential impact on the normal operation of electronic systems, namely the field line coupling effect. The field line coupling effect is an indispensable part of the electromagnetic compatibility analysis and evaluation of electronic systems. Therefore, the cable field line coupling model is one of the necessary models in the electromagnetic compatibility analysis and calculation software.

[0004] At present, the field line coupling model in the electromagnetic compatibility analysis and calculation software is generally an analytical model for cables under regular and simple boundary conditions, such as straight cables on an infinite ground plane. However, under real conditions, the complexity of the cable system is very high, usually showing irregular routing and located under complex boundary conditions (such as complex structural cabins, other surrounding metal structures, etc.), and it is difficult to perform analytical modeling under most conditions. Modeling in the software has to be forced to simplify and apply analytical models to model and solve, resulting in large analysis errors. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art, provide a method and system for modeling irregular cable field line coupling based on current injection probe testing, and solve the deficiencies of the prior art.

[0006] The object of the present invention is achieved by the following technical solution: a modeling method for irregular cable field line coupling based on current injection probe testing, the method comprising:

[0007] Step 1: After the vector network analyzer is calibrated, configure the test system, determine the test frequency band and test point, install a current injection probe at the test point and connect it to the vector network analyzer, measure the first S parameter between each injection point, measure the second S parameter between the probe located at each injection point and the right port of the cable under test, remove the current injection probe, connect the two ports of the vector network analyzer to the two ends of the line under test, and measure the third S parameter;

[0008] Step 2: construct a field line coupling effect model based on the first S parameter, the second S parameter and the third S parameter obtained in step 1.

[0009] The step 1 specifically includes the following contents:

[0010] Step 1: The vector network analyzer performs dual-port calibration when both port 1 and port 2 are connected to the test coaxial line;

[0011] Step 2: For the cable under test, terminate the left and right sides with matching gate chassis to realize the interconnection between the core wires of the cable and the coaxial test port, and respectively interconnect the left and right ends of the core wire selected by configuring the left and right gate chassis, and interconnect the coaxial output port of the left gate chassis with the vector network analyzer port 2 through the RF coaxial line, and connect the coaxial output port of the right gate chassis to a 50-ohm matching load, wherein the coaxial output port of the left gate chassis is the left port L, and the coaxial output port of the right gate chassis is the right port R;

[0012] Step 3: Determine the test frequency band according to actual requirements;

[0013] Step 4: Divide the cable into N segments according to the frequency and cable structure complexity, take the center point of each segment as the injection point, and mark them as injection point 1 to injection point N;

[0014] Step 5: Install a current injection probe at injection point 1, and interconnect the injection probe with port 1 of the vector network analyzer through a radio frequency coaxial line;

[0015] Step 6: Measure the full-band dual-port S parameters between the injection port e and the left port L, denoted as S 1L ;

[0016] Step 7: Repeat the measurements of Step 6 and Step 7 at each injection point in the order of injection point numbers. The results are recorded as S 2L To S NL ;

[0017] Step 8. Connect the left port L to a 50 ohm matched load and the vector network analyzer port 2 to the right port R. Repeat steps 5 to 7 and record the two-port S parameters between the probe and the right port R when the probe is located at each injection point, which are recorded as S 1R To S NR ;

[0018] Step 9: Remove the current injection probe, connect port 1 and port 2 of the vector network analyzer to the left port L and the right port R respectively, and measure and record the S parameters of the left and right ports, recorded as S LR .

[0019] The step 2 specifically includes the following contents:

[0020] Enter the cable axial field strength E1 to E1 at all injection points N , the lengths of all cable segments l1 to l N , the selected core line is terminated with impedance Z at the left port L L , the selected core wire is terminated with impedance Z at the right port R R ;

[0021] Combining the three S parameters, the mathematical representation of the model is:

[0022] Where Z0 is the characteristic impedance of the test equipment, S xx,ij represents the element in the i-th row and j-th column of the matrix, xx represents a number in 1R-NR and 1L-NL, and Z T The transfer impedance of the current injection probe.

[0023] The step 2 also includes: if there are multiple core wires in the cable that need to be tested and modeled, the corresponding core wires are selected using the left and right gating chassis, and steps 2 to 10 are repeated to form a field line coupling effect model for different core wires.

[0024] A modeling system for irregular cable field line coupling based on current injection probe testing, the system comprising an S parameter measurement module and a field line coupling effect model building module;

[0025] The S parameter measurement module is configured to configure the test system after the vector network analyzer is calibrated, and determine the test frequency band and test point, install a current injection probe at the test point and connect it to the vector network analyzer, respectively measure the first S parameter between each injection point, measure the second S parameter between the probe located at each injection point and the right port of the cable under test, remove the current injection probe, connect the two ports of the vector network analyzer to the two ends of the line under test, and measure the third S parameter;

[0026] The field-line coupling effect model construction module is configured to construct a field-line coupling effect model according to the first S parameter, the second S parameter and the third S parameter obtained by the S parameter measurement module.

[0027] The parameter measurement module specifically implements the following steps:

[0028] Step 1: The vector network analyzer performs dual-port calibration when both port 1 and port 2 are connected to the test coaxial line;

[0029] Step 2: For the cable under test, terminate the left and right sides with matching gate chassis to realize the interconnection between the core wires of the cable and the coaxial test port, and respectively interconnect the left and right ends of the core wire selected by configuring the left and right gate chassis, and interconnect the coaxial output port of the left gate chassis with the vector network analyzer port 2 through the RF coaxial line, and connect the coaxial output port of the right gate chassis to a 50-ohm matching load, wherein the coaxial output port of the left gate chassis is the left port L, and the coaxial output port of the right gate chassis is the right port R;

[0030] Step 3: Determine the test frequency band according to actual requirements;

[0031] Step 4: Divide the cable into N segments according to the frequency and cable structure complexity, take the center point of each segment as the injection point, and mark them as injection point 1 to injection point N;

[0032] Step 5: Install a current injection probe at injection point 1, and interconnect the injection probe with port 1 of the vector network analyzer through a radio frequency coaxial line;

[0033] Step 6: Measure the full-band dual-port S parameters between the injection port e and the left port L, denoted as S 1L ;

[0034] Step 7: Repeat the measurements of Step 6 and Step 7 at each injection point in the order of injection point numbers. The results are recorded as S 2L To S NL ;

[0035] Step 8. Connect the left port L to a 50 ohm matched load and the vector network analyzer port 2 to the right port R. Repeat steps 5 to 7 and record the two-port S parameters between the probe and the right port R when the probe is located at each injection point, which are recorded as S 1R To S NR ;

[0036] Step 9: Remove the current injection probe, connect port 1 and port 2 of the vector network analyzer to the left port L and the right port R respectively, and measure and record the S parameters of the left and right ports, recorded as S LR .

[0037] The field line coupling effect model construction module specifically implements the following steps:

[0038] Enter the cable axial field strength E1 to E1 at all injection points N , the lengths of all cable segments l1 to l N , the selected core line is terminated with impedance Z at the left port L L , the selected core wire is terminated with impedance Z at the right port R R ;

[0039] Combining the three S parameters, the mathematical representation of the model is:

[0040] Where Z0 is the characteristic impedance of the test equipment, S xx,ij represents the element in the i-th row and j-th column of the matrix, xx represents a number in 1R-NR and 1L-NL, and Z T The transfer impedance of the current injection probe.

[0041] The field-line coupling effect model building module also includes: if there are multiple cores in the cable that need to be tested and modeled, the corresponding core is selected using the left and right gating chassis, and steps 2 to 10 are repeated to form field-line coupling effect models for different cores.

[0042] The present invention has the following advantages: a method and system for modeling irregular cable field line coupling based on current injection probe testing, avoiding the limitation that traditional analytical / semi-analytical modeling is difficult to apply to complex conditions, avoiding the huge amount of calculation for direct full-wave calculation, converting the external field into an equivalent voltage source based on physical principles, and directly establishing the relationship between the external field and the port coupling value through testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Schematic diagram of the test configuration of the method of the present invention. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present application provided below in conjunction with the drawings is not intended to limit the scope of protection of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application. The present invention is further described below in conjunction with the drawings.

[0045] The present invention specifically relates to a method for modeling irregular cable field line coupling based on current injection probe testing. The method utilizes the basic principle that both the current injection probe and the external electromagnetic field can be equivalent to an online series voltage source. The current injection probe coupling test is used to measure in advance the scattering parameter matrix of the injection port at each position on the cable and the cable terminal port, obtain the mathematical relationship between the equivalent voltage source at the injection point and the coupled current at the cable port, establish a characterization model, and thereby achieve the ability to predict the cable coupled current under any external field conditions.

[0046] like Figure 1 As shown in the figure, the test object is the cable under test, and the test equipment includes: a two-port vector network analyzer (VNA), a current injection probe, a gate chassis matching the cable under test, a RF coaxial line and adapter, and a 50 ohm matching load; the specific test and modeling process is as follows:

[0047] Step 1: VN calibration: The VN performs dual-port calibration when both port 1 and port 2 are connected to the test coaxial line.

[0048] Step 2: Configure the test system: Figure 1 As shown, for the cable under test, matching gate chassis are terminated on the left and right sides to realize the interconnection between the core wires of the cable and the coaxial test port; through the left and right gate chassis, the left and right ends of the selected core wires are configured to be interconnected with the left and right ports respectively; the coaxial output port (left port) of the left gate chassis is interconnected with the vector network port 2 through the RF coaxial line, and the coaxial output port (right port) of the right gate chassis is connected to a 50 ohm matching load.

[0049] Step 3: Determine the test frequency band: usually 1MHz-400MHz is selected, but it can also be defined by the user.

[0050] Step 4. Determine the test points. Divide the cable into N sections according to the frequency and the complexity of the cable structure. Take the center point of each section as the injection point (marked with a black dot in the figure), marked as injection point 1 to injection point N. The cable sections should be as equal in length as possible, and the interval between the injection points should be no less than 1 / 4 of the wavelength corresponding to the highest frequency.

[0051] Step 5: Install a current injection probe at injection point 1, and interconnect the injection probe with vector network port 1 through an RF coaxial line.

[0052] Step 6: Measure the full-band two-port scattering parameters (S parameters) between the injection port e and the left port L, denoted as S 1L .

[0053] Step 7: Repeat the measurements of steps 6-7 at each injection point in the order of injection point numbers, and record them as S 2L To S NL .

[0054] Step 8: Connect the left port L to a 50 ohm matching load, connect the vector network port 2 to the right port R, repeat steps 5-7, and record the two-port S parameters between the probe and the right port R when the probe is located at each injection point, which are recorded as S 1R To S NR .

[0055] Step 9: Remove the current injection probe, connect port 1 and port 2 of the vector network to the left port L and the right port R respectively, and measure and record the S parameters of the left and right ports, recorded as S LR.

[0056] Step 10: Based on the above data, a field line coupling effect model is formed.

[0057] Step 11: If there are multiple cores in the cable that need to be tested and modeled, use the left and right selection chassis to select the corresponding cores to connect, and repeat the above steps 2 to 10 to form models for different cores.

[0058] Furthermore, after obtaining parameter data according to the test steps, the field line coupling effect can be modeled according to the following method. The specific model characterization is as follows:

[0059] Model input parameters: Cable axial field strength E1 to E2 at all injection points N , the lengths of all cable segments l1 to l N , the selected core wire is terminated with impedance Z at the left port L , the selected core wire is terminated with impedance Z at the right port R ;

[0060] Model output parameter: coupling current I at the left port L , the coupling current I at the right port R ;

[0061] Mathematical representation of the model:

[0062]

[0063] Where Z0 is the characteristic impedance of the test equipment (50 ohms); S xx,ij represents the element in the i-th row and j-th column of the matrix, xx represents a number in 1R-NR and 1L-NL; Z T It is the transfer impedance of the current injection probe, representing the equivalent voltage source value coupled on the cable under unit injection current value. It can be obtained from the product manual of the current probe or through calibration.

[0064] Furthermore, the constructed model is mainly used for the analysis of field line coupling effects in electromagnetic computing software. Through full-wave simulation and other calculation processes, the electromagnetic computing software can obtain all field distributions at and near the location of the cable. Under this condition, the software can call this model to calculate the coupling current at the cable terminal, and then obtain the coupling voltage, power, etc., to realize the analysis of field line coupling effects.

[0065] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used for various other combinations, modifications and improvements, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. A modeling method for irregular cable field line coupling based on current injection probe testing, characterized in that: The method comprises: Step 1: After the vector network analyzer is calibrated, configure the test system, determine the test frequency band and test point, install a current injection probe at the test point and connect it to the vector network analyzer, measure the first S parameter between each injection point, measure the second S parameter between the probe located at each injection point and the right port of the cable under test, remove the current injection probe, connect the two ports of the vector network analyzer to the two ends of the line under test, and measure the third S parameter; Step 2: construct a field line coupling effect model based on the first S parameter, the second S parameter and the third S parameter obtained in step 1.

2. The irregular cable field line coupling modeling method based on current injection probe testing according to claim 1 is characterized in that: The step 1 specifically includes the following contents: Step 1: The vector network analyzer performs dual-port calibration when both port 1 and port 2 are connected to the test coaxial line; Step 2: For the cable under test, terminate the left and right sides with matching gate chassis to realize the interconnection between the core wires of the cable and the coaxial test port, and respectively interconnect the left and right ends of the core wire selected by configuring the left and right gate chassis, and interconnect the coaxial output port of the left gate chassis with the vector network analyzer port 2 through the RF coaxial line, and connect the coaxial output port of the right gate chassis to a 50-ohm matching load, wherein the coaxial output port of the left gate chassis is the left port L, and the coaxial output port of the right gate chassis is the right port R; Step 3: Determine the test frequency band according to actual requirements; Step 4: Divide the cable into N segments according to the frequency and cable structure complexity, take the center point of each segment as the injection point, and mark them as injection point 1 to injection point N; Step 5: Install a current injection probe at injection point 1, and interconnect the injection probe with port 1 of the vector network analyzer through a radio frequency coaxial line; Step 6: Measure the full-band dual-port S parameters between the injection port e and the left port L, denoted as S 1L ; Step 7: Repeat the measurements of Step 6 and Step 7 at each injection point in the order of injection point numbers. The results are recorded as S 2L To S NL ; Step 8. Connect the left port L to a 50 ohm matched load and the vector network analyzer port 2 to the right port R. Repeat steps 5 to 7 and record the two-port S parameters between the probe and the right port R when the probe is located at each injection point, which are recorded as S 1R To S NR ; Step 9: Remove the current injection probe, connect port 1 and port 2 of the vector network analyzer to the left port L and the right port R respectively, and measure and record the S parameters of the left and right ports, recorded as S LR .

3. The irregular cable field line coupling modeling method based on current injection probe testing according to claim 2 is characterized in that: The step 2 specifically includes the following contents: Enter the cable axial field strength E1 to E1 at all injection points N , the lengths of all cable segments l1 to l N , the selected core line is terminated with impedance Z at the left port L L , the selected core wire is terminated with impedance Z at the right port R R ; Combining the three S parameters, the mathematical representation of the model is: Where Z0 is the characteristic impedance of the test equipment, S xx,ij represents the element in the i-th row and j-th column of the matrix, xx represents a number in 1R-NR and 1L-NL, and Z T The transfer impedance of the current injection probe.

4. The irregular cable field line coupling modeling method based on current injection probe testing according to claim 2 is characterized in that: The step 2 also includes: if there are multiple core wires in the cable that need to be tested and modeled, the corresponding core wires are selected using the left and right gating chassis, and steps 2 to 10 are repeated to form a field line coupling effect model for different core wires.

5. Irregular cable field line coupling modeling system based on current injection probe test, characterized by: The system includes an S-parameter measurement module and a field-line coupling effect model building module; The S parameter measurement module is configured to configure the test system after the vector network analyzer is calibrated, and determine the test frequency band and test point, install a current injection probe at the test point and connect it to the vector network analyzer, respectively measure the first S parameter between each injection point, measure the second S parameter between the probe located at each injection point and the right port of the cable under test, remove the current injection probe, connect the two ports of the vector network analyzer to the two ends of the line under test, and measure the third S parameter; The field-line coupling effect model building module is configured to build a field-line coupling effect model according to the first S parameter, the second S parameter and the third S parameter obtained by the S parameter measurement module.

6. The irregular cable field line coupling modeling system based on current injection probe testing according to claim 5, characterized in that: The parameter measurement module specifically implements the following steps: Step 1: The vector network analyzer performs dual-port calibration when both port 1 and port 2 are connected to the test coaxial line; Step 2: For the cable under test, terminate the left and right sides with matching gate chassis to realize the interconnection between the core wires of the cable and the coaxial test port, and respectively interconnect the left and right ends of the core wire selected by configuring the left and right gate chassis, and interconnect the coaxial output port of the left gate chassis with the vector network analyzer port 2 through the RF coaxial line, and connect the coaxial output port of the right gate chassis to a 50-ohm matching load, wherein the coaxial output port of the left gate chassis is the left port L, and the coaxial output port of the right gate chassis is the right port R; Step 3: Determine the test frequency band according to actual requirements; Step 4: Divide the cable into N segments according to the frequency and cable structure complexity, take the center point of each segment as the injection point, and mark them as injection point 1 to injection point N; Step 5: Install a current injection probe at injection point 1, and interconnect the injection probe with port 1 of the vector network analyzer through a radio frequency coaxial line; Step 6: Measure the full-band dual-port S parameters between the injection port e and the left port L, denoted as S 1L ; Step 7: Repeat the measurements of Step 6 and Step 7 at each injection point in the order of injection point numbers. The results are recorded as S 2L To S NL ; Step 8. Connect the left port L to a 50 ohm matched load and the vector network analyzer port 2 to the right port R. Repeat steps 5 to 7 and record the two-port S parameters between the probe and the right port R when the probe is located at each injection point, which are recorded as S 1R To S NR ; Step 9: Remove the current injection probe, connect port 1 and port 2 of the vector network analyzer to the left port L and the right port R respectively, and measure and record the S parameters of the left and right ports, recorded as S LR .

7. The irregular cable field line coupling modeling system based on current injection probe testing according to claim 6, characterized in that: The field line coupling effect model construction module specifically implements the following steps: Enter the cable axial field strength E1 to E1 at all injection points N , the lengths of all cable segments l1 to l N , the selected core line is terminated with impedance Z at the left port L L , the selected core wire is terminated with impedance Z at the right port R R ; Combining the three S parameters, the mathematical representation of the model is: Where Z0 is the characteristic impedance of the test equipment, S xx,ij represents the element in the i-th row and j-th column of the matrix, xx represents a number in 1R-NR and 1L-NL, and Z T The transfer impedance of the current injection probe.

8. The irregular cable field line coupling modeling system based on current injection probe testing according to claim 6, characterized in that: The field-line coupling effect model building module also includes: if there are multiple cores in the cable that need to be tested and modeled, the corresponding core is selected using the left and right gating chassis, and steps 2 to 10 are repeated to form field-line coupling effect models for different cores.

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