A power conduction transmit data conversion method based on load impedance pulling

Abstract

This invention relates to a power conducted emission data conversion method based on load impedance pulling, comprising: constructing a power port conducted emission test environment; testing and acquiring the conducted emission interference voltage of the power port of the test object; calculating the terminal voltage on the power transmission line according to the voltage division relationship; adjusting the impedance of the LISN and connecting it to the test circuit; testing and acquiring the conducted emission interference voltage of the power port of the test object again; calculating the terminal voltage on the adjusted power transmission line; calculating the mapping model of the equivalent power conducted interference source of the test object based on the two calculated terminal voltages; testing and acquiring the impedance characteristics of the power end of the actual platform; and predicting the conducted emission interference of the power port of the test object after actual installation using the mapping model. This invention, through a combination of measurement and calculation, maximizes the advantages of both methods, significantly saves modeling costs, and simultaneously characterizes the true conducted emission characteristics of the device's power port while predicting its performance in complex scenarios.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic compatibility testing, and in particular to a power conduction emission data conversion method based on load impedance pulling. Background Technology

[0002] To ensure the stable and reliable operation of electronic equipment, the power supply plays an increasingly important role in electronic equipment systems. For a long time, the development of electronic equipment has placed high demands on the electromagnetic compatibility of power supply ports. Currently, the electromagnetic compatibility assessment method for power supply ports relies on an ideal anechoic chamber environment. The test environment is built according to relevant standards, and rigorous tests are conducted. The electromagnetic compatibility is then evaluated based on the test results.

[0003] The conducted emission standard test of the power supply can reflect the degree of interference transmitted from the internal interference source of the equipment to the power supply network through the power port to a certain extent. The interference frequency and amplitude can be observed through the standard test results. However, the test device specified in the standard is to ensure the standardization and repeatability of the test results, and does not represent the interference level of the equipment under actual working conditions. The power supply cable network of the actual platform is complex and diverse. After the equipment is installed, the impedance characteristics of the load and the power supply change, which will also affect the magnitude of conducted interference.

[0004] Current electromagnetic compatibility (EMC) standards are conducted in anechoic chambers to provide a relatively ideal testing environment. However, during the mapping process from the anechoic chamber to the actual testing platform, impedance mismatch can occur, leading to a significant difference between the actual transmission characteristics of interference signals and the standard test results. Ultimately, equivalence cannot be achieved. This is because in anechoic chamber testing, the test LISN connects the power supply terminal and the power port of the test object (DAMP). The LISN improves power quality, isolates power supply interference, and prevents interference signals generated by the DAMP from coupling into the power system. However, the impedance of the LISN is relatively fixed to meet the test matching requirements. When the device is actually used on the testing platform, the impedance characteristics of the power supply terminal are different from those when using the LISN. This results in the actual power signal transmission characteristics differing from those in the standard test. Therefore, the results of the standard test cannot fully reflect the actual situation. Furthermore, real-time monitoring is not available in actual testing, making it impossible to effectively observe signal changes at the power port after the DAMP is installed. Thus, the current evaluation of the power emission characteristics of the device on the testing platform can only rely on the overall evaluation of the response characteristics after system integration and cannot separately evaluate the conducted emission characteristics of the power port after the device is installed. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a power conduction transmission data conversion method based on load impedance pulling, which solves the deficiencies of the prior art.

[0006] The objective of this invention is achieved through the following technical solution: a power conduction transmission data conversion method based on load impedance pulling, the data conversion method comprising:

[0007] Construct a conducted emission test environment for the power port according to the standard requirements, test and obtain the conducted emission interference voltage of the power port of the test object, and calculate the terminal voltage on the power transmission line according to the voltage division relationship.

[0008] Adjust the impedance of the LISN, connect the adjusted LISN to the test circuit, test again to obtain the conducted emission interference voltage at the power port of the test object, and calculate the terminal voltage on the adjusted power transmission line.

[0009] The mapping model of the equivalent power source conducted interference source of the test specimen is calculated based on the terminal voltages calculated twice.

[0010] The impedance characteristics of the power supply terminal of the actual platform are obtained through testing, and the conducted emission interference of the power port after the test object is installed is predicted by the mapping model.

[0011] The test acquires the conducted emission interference voltage at the power port of the test object, and calculates the terminal voltage on the power transmission line based on the voltage divider relationship, including:

[0012] The LISN port scanning interference voltage V was obtained through standard power supply electromagnetic interference tests. LISN ;

[0013] The transmission line termination voltage V(l) and the LISN monitoring terminal voltage V are obtained based on the LISN circuit and the voltage divider relationship. LISN The expression for the relation is The transmission line termination voltage V(l) is calculated based on the port voltage obtained from the LISN end test.

[0014] The general expressions for voltage and current at any point on a transmission line can be calculated based on transmission line theory. Substituting z = 0 and z = l respectively, we can obtain the expressions for the voltage and current at the incident and terminal ends of the transmission line. Based on the voltage V(l) and current I(l) at the terminal end of the transmission line, we can then calculate the voltage distribution on the transmission line. and current distribution

[0015] By combining the two expressions for the transmission line voltage, the transmission line termination voltage V(l) can be constructed, and the interference amplitude V can be calculated. S and internal resistance Z S The equation is Γ S Γ is the power supply voltage reflection coefficient. L This is the load voltage reflection coefficient.

[0016] The impedance of the LISN is adjusted, and the adjusted LISN is connected to the test circuit. The conducted emission interference voltage at the power port of the test object is measured again, and the termination voltage on the adjusted power transmission line is calculated, including:

[0017] The impedance characteristics of the LISN are determined by changing the values ​​of capacitor, inductor and resistor, and the impedance-frequency curve of the adjusted LISN is obtained by testing with an impedance analyzer to obtain an accurate impedance value.

[0018] The adjusted LISN was reconnected to the test circuit, and the LISN port scan interference V was obtained through the power supply electromagnetic interference standard test. L ′ ISN The terminal voltage V′(l) of the power transmission line is calculated based on the voltage division relationship.

[0019] The calculated terminal voltage V′(l) is combined with the theoretical results for a two-conductor transmission line to obtain... v L Γ represents the load voltage reflection coefficient after adjusting the LIST. S This is the power supply voltage reflection coefficient.

[0020] The mapping model for calculating the equivalent power source conducted interference of the test sample based on the two calculated terminal voltages includes:

[0021] right and Perform modulus extraction to obtain and

[0022] Let Γ L When ′=0, meaning the terminating load is impedance matched to the transmission line, then at this time… This leads to the construction of an equivalent conducted interference source model for the EUT;

[0023] Based on the two calculated terminal voltages, the mapping model of the equivalent power source conducted interference source of the test object is calculated, and finally the frequency-dependent mapping model parameters V of the equivalent power source conducted interference source are obtained. s (f) and Z s (f).

[0024] The test obtains the impedance characteristics of the power supply terminal of the actual platform, and predicts the conducted emission interference at the power port after the test object is installed using a mapping model, including:

[0025] The impedance characteristics of the power supply port to the test object are obtained by testing the power supply line port of the power supply port in the actual platform using an impedance analyzer. The reflection coefficient is calculated based on the impedance characteristics, and the magnitude of the interference signal expressed in voltage form on the transmission line is calculated using the voltage expression on the transmission line.

[0026] This invention offers the following advantages: a power conduction emission data conversion method based on load impedance traction, mapping from standard half-wave anechoic chamber test conditions to actual platform conditions. By altering the LISN impedance characteristics to simulate actual impedance variations, a mapping model of the interference source is obtained. This model characterizes the interference source's own characteristics and is independent of external input signals. Based on this mapping model, the conducted emission characteristics of the test object's power port after actual installation and use can be evaluated to the maximum extent using test data. By combining measurement and calculation, the advantages of both methods are maximized, avoiding the need to obtain information about the test object's internal structure during modeling, significantly saving modeling costs. Simultaneously, it can characterize the actual conducted emission characteristics of the device's power port and predict its performance in complex scenarios. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the process of the present invention;

[0028] Figure 2 This is a schematic diagram illustrating an example of a configuration setup for use as a standard test for electromagnetic interference of power supplies.

[0029] Figure 3 This is the LISN circuit diagram of the present invention;

[0030] Figure 4 This is a schematic diagram of the LISN impedance-frequency curve required by the GJB 151B standard.

[0031] Figure 5 A schematic diagram of the equivalent circuit model of a two-conductor transmission line;

[0032] Figure 6 This is a schematic diagram of the LISN impedance-frequency curve after the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of this application provided below with reference to the accompanying drawings is not intended to limit the scope of protection of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The present invention will be further described below with reference to the accompanying drawings.

[0034] This invention specifically relates to a method for converting conducted emission data from a half-wave anechoic chamber to a physical platform based on load impedance pulling. It uses load pulling to change the impedance characteristics of the power port, achieving different signal transmission states on the power transmission line, all of which can be characterized through testing and theoretical models. An equivalent mapping model of the test object's power port is obtained by jointly analyzing two or more test results. This model is independent of external input and can therefore be directly applied to predicting conducted emissions from the test object's power port on the physical platform. By obtaining the impedance characteristics of the power terminal on the physical platform through testing, the conducted emission characteristics of the test object on any platform can be predicted.

[0035] like Figure 1 As shown, taking the CE102 test as an example, the first step is to construct the power port conducted emission test environment according to the standard requirements. For example... Figure 2 As shown, the test site for transmitting power ports to the emission test is constructed in accordance with the test setup requirements of CE102 power conducted emission test in GJB 151B.

[0036] Adjust the resistor to 1kΩ. At this point, the impedance of the LISN meets the standard requirements. Figure 4 As shown. Through the power supply electromagnetic interference standard test, the voltage V at the monitoring terminal of the linear impedance network is obtained using a receiver. LISN ,according to Figure 3 The circuit diagram and voltage divider relationship can directly give the transmission line terminal voltage V(l) and the linear impedance network monitoring terminal voltage V. LISN The expression is shown in the following formula:

[0037]

[0038] In the formula, R1 and R2 are the resistance values ​​in the LISN circuit, C1 and C2 are the capacitance values ​​in the LISN circuit, ω is the voltage signal transmission, and L is the inductance value in the LISN circuit.

[0039] Based on the linear impedance network monitoring terminal voltage V obtained from the LISN terminal test LISN The transmission line termination voltage V(l) can be obtained by solving.

[0040] like Figure 5 As shown, the general expressions for voltage and current at any point on the transmission line are obtained using transmission line theory. Substituting z = 0 and z = l respectively, the expressions for the voltage and current at the incident end and the terminal end of the transmission line can be obtained. After combining them, the voltage distribution V(z) and current distribution I(z) on the transmission line can be derived based on the terminal voltage V(l) and current I(l).

[0041]

[0042]

[0043] In the formula, β is the phase constant, Z0 is the magnitude of the characteristic impedance of the transmission line, and Z S is the impedance of the equivalent interference source of the device under test, and z is the distance from a specific location on the transmission line to the incident end.

[0044] Among them, the power supply voltage reflection coefficient Γ S and load voltage reflection coefficient Γ L The expression is as follows:

[0045]

[0046]

[0047] Substituting z = 0 and z = l respectively, we can obtain the expressions for the voltage and current at the incident and terminal ends of the transmission line:

[0048]

[0049]

[0050]

[0051]

[0052] Based on the transmission line terminal voltage V(l) and current I(l), the voltage distribution V(z) and current distribution I(z) on the transmission line can be calculated.

[0053]

[0054]

[0055] Choosing the location of the incident end of the transmission line, i.e., z = 0, the voltage at the incident end is:

[0056] By combining the two expressions for the transmission line termination voltage V(z), a solution for the interference amplitude V of the transmission line termination voltage V(l) can be constructed. S and internal resistance Z S The equation:

[0057]

[0058] Adjust the resistor value to 12Ω to keep the LISN impedance around 10Ω. Alternatively, select another channel, add a 150Ω resistor to its output path, and adjust the original circuit's resistor value to 200Ω to keep the output LISN impedance around 100Ω. Use an impedance analyzer to test and obtain the impedance-frequency curve of the adjusted LISN to obtain the accurate impedance Z. L',like Figure 6 As shown.

[0059] According to the standard setup requirements, the adjusted LISN was reconnected to the test loop, and the LISN port sweep frequency interference voltage V was obtained through the power supply electromagnetic interference standard test. L ′ ISN And calculate the terminal voltage V′(l) of the power transmission line based on the voltage division relationship.

[0060] Combining the calculated terminal voltage V′(l) with the theoretical results for a two-conductor transmission line, we obtain the following equation:

[0061]

[0062] Where the load voltage reflection coefficient v L Become Γ L ′, where Z L Substituting the actual impedance value obtained from the impedance analyzer, we get:

[0063]

[0064] Since the terminal measurement result is usually the voltage amplitude (i.e., the magnitude of the voltage phasor), the two equations are moduloed for easier solution, as shown in the following two equations. However, it should be noted that the two equations after moduloing are necessary but not sufficient conditions for solving the two equations, and there may be multiple solutions.

[0065]

[0066]

[0067] Therefore, we further analyze this special case, letting Γ L When ′=0, meaning the terminal load is impedance matched to the transmission line, the second solution equation can be transformed into the following equation:

[0068]

[0069] This leads to the construction of an equivalent conducted interference source model for the device under test. Based on the terminal voltages obtained from the two solutions, the mapping model of the equivalent power source conducted interference source for the test object is then solved. Finally, the frequency-dependent mapping model parameters V of the equivalent power source conducted interference source are obtained. s (f) and Z s (f).

[0070] In the practical testing platform, an impedance analyzer was used to test and obtain the impedance characteristics Z of the power supply port to the test object's power supply line port. L (f) Solve for the reflection coefficient in the actual platform according to the reflection coefficient calculation formula. and Using the voltage expression on the transmission line The magnitude V of the interference signal, expressed as a voltage on the transmission line, can be calculated. z＝0 (f).

[0071]

[0072] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and improvements, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A power conduction transmit data conversion method based on load impedance pulling, characterized in that: The data conversion method includes: Construct a conducted emission test environment at the power port, test and obtain the conducted emission interference voltage at the power port of the test object, and calculate the terminal voltage on the power transmission line based on the voltage division relationship; Adjust the impedance of the LISN, connect the adjusted LISN to the test circuit, test again to obtain the conducted emission interference voltage at the power port of the test object, and calculate the terminal voltage on the adjusted power transmission line. The mapping model of the equivalent power source conducted interference source of the test specimen is calculated based on the terminal voltages calculated twice. The impedance characteristics of the power supply terminal of the actual platform are obtained by testing, and the conducted emission interference of the power supply port after the test object is installed is predicted by the mapping model. The test acquires the conducted emission interference voltage at the power port of the test object, and calculates the terminal voltage on the power transmission line based on the voltage divider relationship, including: The LISN port scanning interference voltage was obtained through standard power supply electromagnetic interference tests. ; The transmission line termination voltage is obtained based on the LISN circuit and voltage divider relationship. Voltage at LISN monitoring terminal The expression for the relation is The transmission line termination voltage is calculated based on the port voltage obtained from the LISN end test. ; The expressions for voltage and current at any point on a transmission line are calculated based on transmission line theory. Substitute them respectively and This yields the expressions for the voltage and current at the incident and termination ends of the transmission line. Based on the transmission line termination voltage... and current This allows for the calculation of the voltage distribution on the transmission line. and current distribution ; By combining the two expressions for the transmission line voltage, the transmission line termination voltage can be constructed. Calculate the interference amplitude and internal resistance The equation is , The power supply voltage reflection coefficient, The load voltage reflection coefficient; The impedance of the LISN is adjusted, and the adjusted LISN is connected to the test circuit. The conducted emission interference voltage at the power port of the test object is measured again, and the termination voltage on the adjusted power transmission line is calculated, including: The impedance characteristics of the LISN are adjusted by changing the values ​​of capacitor, inductor and resistor, and the impedance-frequency curve of the adjusted LISN is obtained by testing with an impedance analyzer to obtain an accurate impedance value. The adjusted LISN was reconnected to the test circuit, and the LISN port scan interference was obtained through the power supply electromagnetic interference standard test. The terminal voltage of the power transmission line is calculated based on the voltage divider relationship. ; Calculated terminal voltage Combining the theoretical results with those of two-conductor transmission lines, we obtain , To adjust the load voltage reflection coefficient after LISN; The mapping model for calculating the equivalent power source conducted interference of the test sample based on the two calculated terminal voltages includes: right and Perform modulus extraction to obtain and ; make = 0, meaning the terminating load is impedance matched to the transmission line impedance. Thus, an equivalent conducted interference source model for EUT is constructed; Based on the terminal voltages calculated twice, the mapping model of the equivalent power source conducted interference source of the test object is calculated, and finally the frequency-dependent mapping model parameters of the equivalent power source conducted interference source are obtained. and .

2. The power conduction-transmit data conversion method based on load impedance pulling according to claim 1, characterized in that: The test obtains the impedance characteristics of the power supply terminal of the actual platform, and predicts the conducted emission interference at the power port after the test object is installed using a mapping model, including: The impedance characteristics of the power supply port to the test object are obtained by testing the power supply line port of the power supply port in the actual platform using an impedance analyzer. The reflection coefficient is calculated based on the impedance characteristics, and the magnitude of the interference signal on the transmission line in voltage form is calculated using the voltage expression on the transmission line.

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