An electromagnetic compatibility conducted immunity calibration system and calibration method

Abstract

This invention relates to the field of electromagnetic compatibility (EMC) conducted immunity testing technology, and discloses an EMC conducted immunity calibration system and calibration method. The system includes a signal generation module, a coupling / decoupling network adaptive assembly system, a calibration load path system, an auxiliary equipment termination system, and a grounding protection system. It can adapt to different types of coupling / decoupling networks, normalize the calibration process, and reduce calibration uncertainty, introducing 17.9% less uncertainty than conventional methods. This invention also discloses an automatic calibration method that optimizes the conducted immunity calibration process. It can set the initial level through an algorithm, reduce the target level addressing time, decrease calibration time, and increase the effective detection time ratio. By embedding various parameters of the measured product into each stage of the calibration process, it can better simulate the actual product testing process, improving calibration accuracy and applicability.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic compatibility conducted immunity testing technology, and in particular to an electromagnetic compatibility conducted immunity calibration system and calibration method. Background Technology

[0002] Conducted immunity testing is an important electromagnetic compatibility (EMC) test widely used in multimedia equipment, medical devices, rail transportation, new energy vehicles, robots, and other fields. This test is the mainstream test item for power line immunity testing in the field of EMC testing in various industries, and it plays a decisive role in the power line immunity performance of related products.

[0003] Electromagnetic compatibility laboratories often need to invest a lot of time and resources when calibrating conducted immunity. The calibration system has poor stability and repeatability, the calibration time is long, and the experience requirements of the personnel are also very high. However, the accuracy is generally not high, which introduces a large degree of uncertainty into conducted immunity testing. There is room for improvement in both efficiency and accuracy. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing an electromagnetic compatibility conducted immunity calibration system and method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An electromagnetic compatibility conducted immunity calibration system includes a signal generation module, a coupling-decoupling network adaptive assembly system, a calibration load path system, and an auxiliary equipment termination system.

[0007] The signal generation module, connected to the coupling-decoupling network adaptive assembly system, is used to generate calibrated radio frequency signals to the coupling-decoupling network adaptive assembly system.

[0008] The coupling-decoupling network adaptive assembly system connects the calibration load path system and the auxiliary equipment termination system respectively, coupling the RF signal to the calibration load path system in common mode and performing RF shielding decoupling on the auxiliary equipment termination system;

[0009] The calibration load path system is used to simulate the test sample and complete the impedance matching function to obtain the calibrated RF power.

[0010] Auxiliary equipment termination system, used to simulate the auxiliary equipment environment of the product during testing.

[0011] As a further preferred embodiment, the signal generation module includes an RF signal source, a power amplifier, an attenuator, an RF switch, and a network analyzer; the RF signal source, power amplifier, attenuator, and RF switch are sequentially connected in circuit; the RF switch is also selectively connected to the network analyzer and the coupling / decoupling network adaptive assembly system.

[0012] The adaptive assembly system with coupling and decoupling network includes a coupling and decoupling network. The coupling and decoupling network can be replaced with an applicable model according to the test product. The coupling and decoupling network is connected to the RF switch in a circuit.

[0013] The calibration load path system includes a common-mode port merging device, an impedance converter, an RF switch, a power meter, an adaptive matching load, and a network analyzer. The common-mode port merging device, impedance converter, and RF switch are connected in sequence. The RF switch is also optionally connected to the probes of the network analyzer and the power meter. The adaptive matching load is located on the probe.

[0014] The power meter probe measures and records the radio frequency power during the calibration process, and the adaptive matching load matches the radio frequency impedance during the calibration process.

[0015] The auxiliary equipment termination system includes a common-mode port merging device II, an impedance converter II, an RF switch III, and a load impedance connected in sequence. The RF switch III controls the connection between the impedance converter II and the load impedance.

[0016] As a further preferred embodiment, the calibration system also includes a grounding protection system, which includes a metal grounding plate. The coupling-decoupling network adaptive assembly system, the calibration load path system, and the auxiliary equipment termination system are all located on the metal grounding plate. A digital multimeter is arranged on the metal grounding plate, and the probes of the digital multimeter are respectively connected to the ground and the housing of the coupling-decoupling network.

[0017] A calibration method for an electromagnetic compatibility conducted immunity calibration system includes the following steps:

[0018] Step 1: Based on the actual target voltage being tested, select a calibration target voltage U0 of the same magnitude, with a frequency variation step k, where k ≤ 1%, and a calibration starting frequency f. min and calibration termination frequency f max Set the current calibration frequency f = f min Select the matching coupling / decoupling network, i.e., CDN-M1 to M5, based on the actual power cord type of the product being tested.

[0019] Step 2: Calculate the initial level setting value U of the corresponding RF signal source. S0 Set the frequency of the radio frequency signal source to f and the level value to U. S=U S0 ;

[0020] Step 3: Connect the RF output port of the RF signal source to the RF input port of the power amplifier, and connect the RF output port of the power amplifier to the input port of the attenuator. Switch RF switch one to network analyzer one and test the VSWR of the attenuator output port. If the VSWR is <2dB, continue to step 4.

[0021] Step 4: Determine the electrical parameters of the power cord of the actual test product: Resistance R pl Inductor L pl Capacitor C pl Determine the electrical parameters of the output port of the coupling / decoupling network that match the actual product type being tested: resistance R 201 Inductor L 201 Capacitor C 201 Through the formula:

[0022]

[0023] Calculate the RF impedance of the calibration output port, switch RF switch one to connect the coupling decoupling network, switch RF switch two to connect the network analyzer two, test the RF impedance corresponding to the frequency f of the output port of impedance converter one, if the deviation from the RF impedance of the calibration output port is less than 20%, then complete the automatic impedance matching through the subsequent adaptive matching load, and continue to step five.

[0024] Step 5: Switch RF switch 2 to connect probe. The output port of common mode port merging device 2 is connected to the input port of RF switch 3 through impedance converter 2. RF switch 3 is connected to the load impedance to realize the RF performance of the simulated power supply. Then, the first level value U1 is obtained by testing with the probe of the power meter.

[0025] Step Six: If the first level value U1 meets the requirements... If the scope requirements are met, proceed to step seven;

[0026] Step 7: Disconnect RF switch three from the load impedance and use the power meter probe to obtain the second level value U2; if |U1-U2|≤1.6dB, select the larger result between U1 and U2 and record it as the test level U, and record the corresponding calibration frequency f, test level U, calibration target voltage U0, and signal source level U. S And continue to step eight;

[0027] Step 8: Adjust the calibration frequency f to f×(1+k), and check if the adjustment result is ≤f max If yes, repeat steps two through seven; if no, end the calibration task.

[0028] Step 9: Export the calibration frequency f, test level U, calibration target voltage U0, and signal source level U for all calibration points. S This forms the calibration database.

[0029] As a further preferred option, before step one, measure the resistance between the metal casing of the coupling-decoupling network and the grounding point using a digital multimeter. If it is ≤4Ω, proceed to step two. If it is >4Ω, check the grounding protection system until it meets the requirements, then proceed to step one.

[0030] In step three, if the VSWR is ≥2dB, shut down the system and check whether the connections of each port of the signal generation module are normal, and repeat step two.

[0031] In step four, if the deviation exceeds 20%, shut down the system to check the RF connections between the signal generation system, coupling / decoupling network, common-mode port merging device, and impedance converter, and then repeat step four until the requirements are met.

[0032] In step six, if the first level value U1 does not meet the requirements... If the signal source level U exceeds the specified range requirement, then the signal source level will be adjusted accordingly. S Lower the voltage by 1.5dB and repeat step five. If the voltage is still below the required range, then adjust the signal source level U. S Increase the value by 1.5 dB and repeat step five until the result meets the range requirements;

[0033] In step seven, if |U1-U2|>1.6dB, it indicates that the decoupling function of the coupling-decoupling network has degraded, and the calibration needs to be terminated to check the coupling-decoupling network.

[0034] As a further preferred solution, the calibration parameters and layout need to be adjusted according to the performance parameters of the test product. During the calibration process, the power line phase type (including single-phase single wire, single-phase two wire, single-phase three wire, three-phase four wire, and three-phase five wire), power line shielding type (including shielded and unshielded wire), and power line electrical parameters (including resistance, inductance, and capacitance) are adjusted to optimize the calibration process, more accurately simulate the actual test scenario, and improve the accuracy of the calibration results.

[0035] If it is an unshielded cable, the calibration load path system is in an unshielded state during calibration. If it is a shielded cable, the calibration load path system needs to be covered with a metal shielding mesh during calibration and connected to the metal shell of the coupling / decoupling network and the metal grounding plate. The power meter and network analyzer are connected to the metal shielding mesh outside the metal shielding mesh through shielded cables. To avoid short circuits, a thin layer of shielding material is added between the calibration load path system and the metal shielding mesh.

[0036] As a further preferred option, in step two, the initial level setting value of the RF signal source is:

[0037]

[0038] Among them, U s0 This is the initial level setting value of the RF signal source, U0 is the calibration target voltage, and G... A R is the voltage gain of the power amplifier, T is the voltage attenuation factor of the attenuator, and R is the voltage gain of the power amplifier. 103 R is the output impedance of the attenuator. 201 It is the common-mode impedance of the coupling-decoupling network, R 302 R is the conversion resistance value of impedance converter one. 306 It is the resistance value for adaptive matching load.

[0039] Beneficial effects: The electromagnetic compatibility conducted immunity calibration system and method disclosed in this invention optimizes the calibration process of conducted immunity. It can set the initial level through an algorithm, reduce the target level addressing time, reduce calibration time, and increase the proportion of effective detection time. By embedding various parameters of the measured product into each stage of the calibration process, it can better simulate the test process of the measured product, improve the calibration accuracy and applicability, and reduce calibration uncertainty. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the connection structure of the various components of the calibration system of the present invention;

[0041] Figure 2 This is a flowchart of the calibration method of the present invention;

[0042] Figure 3 This is the circuit equivalent diagram of the present invention;

[0043] In the diagram: 101, RF signal source; 102, power amplifier; 103, attenuator; 104, RF switch one; 105, network analyzer one; 201, coupling / decoupling network; 301, common-mode port merging device one; 302, impedance converter one; 303, RF switch two; 304, probe; 305, power meter; 306, adaptive matching load; 307, network analyzer two; 401, common-mode port merging device two; 402, impedance converter two; 403, RF switch three; 404, load impedance; 5, grounding protection system; 501, grounding bolt; 502, insulated moving handle; 503, grounding copper strip; 504, digital multimeter; 505, metal grounding plate. Detailed Implementation

[0044] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0045] like Figure 1 As shown, the electromagnetic compatibility conducted immunity calibration system of the present invention includes a signal generation module, a coupling-decoupling network adaptive assembly system, a calibration load path system, and an auxiliary equipment termination system.

[0046] The signal generation module, connected to the coupling-decoupling network adaptive assembly system, is used to generate a calibrated RF signal to the coupling-decoupling network adaptive assembly system, which is used to generate an RF power signal and ensure that the VSWR at the signal end meets the requirements.

[0047] The signal generation module includes an RF signal source 101, a power amplifier 102, an attenuator 103, an RF switch 104, and a network analyzer 105; the RF signal source 101, the power amplifier 102, the attenuator 103, and the RF switch 104 are connected in sequence; the RF switch 104 is also connected to the network analyzer 105 and the coupling / decoupling network adaptive assembly system.

[0048] When RF switch 104 is connected to network analyzer 105, it is used to monitor the VSWR of the RF signal output port; when RF switch 104 is connected to coupling / decoupling network 201, it is used to output RF signal.

[0049] The RF signal source 101 has a sweep frequency range of 150kHz-80MHz (this frequency range is the frequency range for conducted immunity testing; normally, the frequency ranges of both the RF signal source 101 and the network analyzer exceed this band, but generally only this band needs to be calibrated according to test requirements). Attention should be paid to the RF energy at the input port of the network analyzer 105; an attenuator should be added.

[0050] The Network Analyzer 105 can provide standing wave ratio (SWR) warnings. The presence of RF SWR can lead to significant power loss in RF lines and cause impedance mismatch. The formula for SWR testing is as follows: This represents the ratio of the maximum voltage to the minimum voltage in the system circuit. In this scheme, the standing wave ratio (VSWR) is required to be less than 2.

[0051] The signal generation module works by transmitting a stable signal source with controllable impedance and a VSWR that meets requirements through a combination of radio frequency components, ensuring the stable transfer of radio frequency energy to the radio frequency input of the coupling / decoupling network.

[0052] The coupling-decoupling network adaptive assembly system connects the calibration load path system and the auxiliary equipment termination system respectively. It couples the RF signal to the calibration load path system in common mode and performs RF shielding decoupling on the auxiliary equipment termination system to ensure that the RF path only passes through the load end and does not leak to the auxiliary equipment end.

[0053] The adaptive assembly system for coupling / decoupling networks includes a coupling / decoupling network 201, a 90° metal grounding fixing device, and M8 fixing screws. The coupling / decoupling network 201 can be replaced with an applicable model according to the test product, that is, the type of coupling / decoupling network 201 (M1 to M5) can be changed according to the type of test power line. The coupling / decoupling network 201 is connected to the RF switch-104 circuit. The electrical parameters of the coupling / decoupling network 201 are generally different from those of the test product. In the subsequent formula calculation, the two are added together to simulate the RF impedance in the actual test environment. Therefore, a judgment criterion is set: if the RF impedance corresponding to the output port of the impedance converter-302 deviates from the RF impedance in the actual test environment by no more than 20%, it is considered that the actual test environment can be simulated and the requirements are met, and the next step can be continued.

[0054] The 90° metal grounding fixing device has an L-shaped structure, with its vertical side clamped to the side of the coupling and decoupling network 201, and its horizontal side fixed to the metal grounding plate 505 by M8 fixing screws.

[0055] To enhance grounding requirements, increase the grounding area, improve conductivity, and reduce grounding impedance, copper screws and nuts are required. The contact surfaces of the screws and nuts need to be polished smooth to increase the contact area. The reinforcement torque is 7 N·m to 10 N·m.

[0056] The casing of the coupling / decoupling network 201 forms a common-mode path reference ground through multiple grounding methods; the coupling / decoupling network 201 includes (CDN-Mx, x = 1-5), where x represents the total number of testable phase wires, neutral wires and protective ground wires. For example, M3 can perform single-phase three-wire product testing with protective ground.

[0057] Specifically, the calibration parameters and setup need to be adjusted according to the performance parameters of the test product. During the calibration process, the power line phase type M1-M5 (single-phase single wire, single-phase two wire, single-phase three wire, three-phase four wire, three-phase five wire), power line shielding type (shielded wire, unshielded wire), and power line electrical parameters (resistance, inductance, capacitance) are adjusted to more accurately simulate the actual test scenario and improve the accuracy of the calibration results.

[0058] If it is an unshielded cable, the calibration load path system is in an unshielded state during calibration. If it is a shielded cable, the calibration load path system needs to be covered with a metal shielding mesh during calibration and connected to the metal shell of the coupling / decoupling network 201 and the metal grounding plate 505. The power meter 305 and the network analyzer 307 are outside the metal shielding mesh and connected to the metal shielding mesh through shielded cables. To avoid short circuits, a thin layer of shielding material is added between the calibration load path system and the metal shielding mesh.

[0059] Specifically, the common-mode path of the coupling-decoupling network 201 can be adapted to different power line specifications through impedance design to connect to the common-mode port merging device 301. For CDN-Mx, x = 1-5, the design value of the resistance on each power line is R = 100*x, ensuring that the bus-to-ground impedance is 100Ω in common-mode mode. Due to the influence of parasitic inductance and capacitive reactance parameters, it is difficult to achieve a completely ideal impedance throughout the entire test frequency band of 0.15-80MHz. A generally feasible design target is 100Ω ± 20Ω.

[0060] The calibration load path system is used to simulate an ideal test sample, perform impedance matching, and obtain the calibrated RF power. The working principle of calibration load path system 3 is to perform impedance matching, thereby obtaining the calibrated RF power according to... Figure 3 The initial level calculation of the signal source is derived, see the derivation process of Formula 1 below;

[0061] The calibration load path system includes a common-mode port merging device 301, an impedance converter 302, an RF switch 303, a power meter 305, an adaptive matching load 306, and a network analyzer 307. The common-mode port merging device 301, impedance converter 302, and RF switch 303 are connected in sequence. The RF switch 303 is also optionally connected to the probe 304 of the network analyzer 307 and the power meter 305. The adaptive matching load 306 is located on the probe 304.

[0062] Common-mode port merging device 301 is a device that combines different phase lines into a single phase line. To adapt to different coupling / decoupling networks, different common-mode port merging devices 301 are used for M1 to M5 to accommodate impedance converters 302 of the same specifications. RF switch 303 switches the connectivity analyzer 307 for impedance testing; when switched to probe 304, calibration is performed using the calibration load path.

[0063] The probe 304 of the power meter 305 measures and records the radio frequency power during the calibration process, and the adaptive matching load 306 performs the matching work for the radio frequency impedance during the calibration process.

[0064] The auxiliary equipment termination system is used to simulate the auxiliary equipment environment of the product during testing. Its working principle is to simulate the auxiliary equipment environment of the product during testing. Generally, it is required that the influence of the auxiliary equipment terminal on the result should not exceed 1.6dB. In this invention, two working conditions, no-load and loaded, were tested using the RF switch 3403, which can complete the verification task of whether the influence of the auxiliary equipment terminal is controllable.

[0065] The auxiliary equipment termination system includes a common-mode port merging device 2 401, an impedance converter 2 402, an RF switch 3 403, and a load impedance 404 connected in sequence. The common-mode port merging device 2 401 is used to realize the common-mode merging function of the auxiliary equipment end RF path of the coupling and decoupling network 201. The impedance converter 2 402 is used to realize impedance matching. A feasible embodiment is a 150-50Ω converter. The RF switch 3 403 controls the connection between the impedance converter 2 402 and the load impedance 404.

[0066] The calibration system also includes a grounding protection system for strengthening the grounding of the calibration system and monitoring leakage current. The grounding protection system includes a metal grounding plate 505, and the coupling-decoupling network adaptive assembly system, calibration load path system, and auxiliary equipment termination system are all located on the metal grounding plate 505.

[0067] A digital multimeter 504 is arranged on the metal grounding plate 505. The probes of the digital multimeter 504 are connected to the ground and the outer shell of the coupling decoupling network 201 respectively. In this invention, when the impedance exceeds 0.5 ohms, it indicates that the grounding effect is not ideal, and calibration is stopped.

[0068] The metal grounding plate 505 is also provided with grounding bolts 501 for fixing to the ground, insulating movable handles 502 for changing the placement area, and grounding copper strips 503 for connecting to the ground.

[0069] During the calibration process, leakage current is monitored using a digital multimeter 504. The entire calibration system is protected by an insulating acrylic shell (not shown in the structural diagram) to ensure the stability and safety of the calibration system.

[0070] A calibration method for an electromagnetic compatibility conducted immunity calibration system allows for full-process control via testing software, enabling efficient and automated calibration. During the entire automated conducted immunity calibration process, the power meter, network analyzer, and signal source are frequency synchronized. The automated calibration method includes the following steps:

[0071] Before step one, use a digital multimeter 504 to measure the resistance between the metal casing of the coupling-decoupling network 201 and the grounding point. If it is ≤4Ω, proceed to step two. If it is >4Ω, check the grounding protection system until it meets the requirements, then proceed to step one.

[0072] Step 1: Based on the actual target voltage being tested, select a calibration target voltage U0 of the same magnitude, with a frequency change step k (the calibration process cannot traverse all frequency points, so it is completed through a selected subset of frequency points; the frequency of the next point in these frequency points is equal to the previous frequency point * (1 + k)), k ≤ 1%, and the calibration starting frequency f. min and calibration termination frequency f maxSet the current calibration frequency f = f min Select the matching coupling / decoupling network 201, i.e., CDN-M1 to M5, based on the actual power cord type of the product being tested.

[0073] Step 2: Calculate the initial level setting value U of the corresponding RF signal source 101. S0 Set the frequency of the radio frequency signal source 101 to f and the level value to U. S =U S0 ;

[0074] Step 3: Connect the RF output port of RF signal source 101 to the RF input port of power amplifier 102, and connect the RF output port of power amplifier 102 to the input port of attenuator 103. Switch RF switch 104 to network analyzer 105. The formula for the VSWR test of network analyzer 105 is as follows: The standing wave ratio (SWR) represents the ratio of the maximum voltage to the minimum voltage in the system circuit. The SWR is required to be less than 2. Test the SWR at the output port of attenuator 103. If the SWR is < 2dB, continue to step four. If the SWR is ≥ 2dB, shut down the system and check whether the connections of each port of the signal generation module are normal, and repeat step two.

[0075] Step 4: Assume the actual electrical parameters of the product's power cord for testing: Resistance R pl Inductor L pl Capacitor C pl Determine the electrical parameters of the output port of the coupling / decoupling network (201) that matches the actual test product type: resistance R 201 Inductor L 201 Capacitor C 201 Through the formula:

[0076]

[0077] Calculate the RF impedance of the calibration output port, switch RF switch 104 to connect to the coupling decoupling network 201, and switch RF switch 303 to connect to the network analyzer 307. Test the RF impedance corresponding to the frequency f of the output port of impedance converter 302. If the deviation from the RF impedance of the calibration output port is less than 20%, automatic impedance matching is completed through the subsequent adaptive matching load 306, and step five continues. However, the larger the difference, the greater the uncertainty. Therefore, it is still necessary to minimize the impact of the difference. Thus, it is necessary to adjust through the adaptive matching load 306 to achieve better matching.

[0078] If the deviation exceeds 20%, shut down the system and check the RF connection between the signal generation system, coupling / decoupling network 201, common-mode port merging device 301 and impedance converter 302, and then repeat step four until the requirements are met.

[0079] Step 5: Switch RF switch 2 303 to connect probe 304. The output port of common mode port merging device 2 401 is connected to the input port of RF switch 3 403 through impedance converter 2 402. RF switch 3 403 is connected to load impedance 404 to realize the RF performance of the simulated power supply. Then, the first level value U1 is obtained by testing with probe 304 of power meter 305.

[0080] Step Six: If the first level value U1 meets the requirements... If the range requirement is not met, continue to step seven; if the result of the first level value U1 does not meet the requirement... If the signal source level U exceeds the specified range requirement, then the signal source level will be adjusted accordingly. S Lower the voltage by 1.5dB and repeat step five. If the voltage is still below the required range, then adjust the signal source level U. S Increase the value by 1.5 dB and repeat step five until the result meets the range requirements;

[0081] Step 7: Disconnect RF switch 403 from load impedance 404, and use probe 304 of power meter 305 to obtain the second level value U2; if |U1-U2|≤1.6dB, select the larger result between U1 and U2 and record it as the test level U, and record the corresponding calibration frequency f, test level U, calibration target voltage U0, and signal source level U. S Continue to step eight; if |U1-U2|>1.6dB, it indicates that the decoupling function of the coupling-decoupling network 201 has decreased, and the calibration check of the coupling-decoupling network 201 needs to be terminated.

[0082] Step 8: Adjust the calibration frequency f to f×(1+k), and check if the adjustment result is ≤f max If yes, repeat steps two through seven; if no, end the calibration task.

[0083] Step 9: Export the calibration frequency f, test level U, calibration target voltage U0, and signal source level U for all calibration points. S The calibration database for this test is shown in Table 1.

[0084] Table 1 Example of calibration data results

[0085]

[0086] Conventional calibration processes gradually increase the signal source level from a low initial value, stopping when the requirement is met. This adjustment process increases calibration time and reduces calibration efficiency. This invention improves the accuracy of the initial calibration value through Formula 1. The derivation of Formula 1 is as follows: First, draw the equivalent circuit diagram based on the schematic diagram, as shown below. Figure 3 As shown, the attenuator output voltage U1 = Us0 ×G A / T, according to the voltage divider principle of circuits Therefore, we can obtain Formula 1 in step two, which is the initial level setting value of the RF signal source 101:

[0087]

[0088] Among them, U s0 This is the initial level setting value of the RF signal source 101, U0 is the calibration target voltage, and G... A R is the voltage gain of power amplifier 102, T is the voltage attenuation factor of attenuator 103, and R is the voltage gain of power amplifier 102. 103 R is the output impedance of attenuator 103. 201 It is the common-mode impedance of the coupling / decoupling network 201, R. 302 This is the conversion resistance value of the impedance converter 302, R. 306 It is the resistance value of an adaptive matching load 306.

[0089] The following data is for illustrative purposes only. In real-world scenarios, it is necessary to obtain a data array of parameters varying with frequency from a measurement report. For ease of demonstration, some parameters are simplified, with U0 = 10V and G... A =105dB, T=6dB, R 103 =50Ω, R 302 =100Ω, R 306 =50Ω.

[0090] Table 2 Typical common-mode impedances of coupling / decoupling networks (excluding termination impedance)

[0091]

[0092]

[0093] The signal source level U at this time can be calculated using Formula 1. s0 The setting parameters are shown in Table 3:

[0094] Table 3: U s0 Initial settings

[0095]

[0096] In one embodiment of the present invention, the radio frequency impedance of the calibration system can be tested using a network analyzer, with a test frequency range of 150kHz-80MHz. Through adaptive impedance compensation, the calibration uncertainty can be reduced.

[0097] Let the mathematical model of the calibration process be:

[0098] V = V RMS +VLAW +P D +P AN +M VC +M AC +R S +R EUT

[0099] The symbols used are explained in Table 4 below:

[0100] Table 4: Explanation of Symbols for Calibration Digital Model

[0101]

[0102]

[0103] Formula 2 for calculating the combined standard uncertainty is as follows:

[0104]

[0105] The uncertainty can be analyzed and evaluated based on its source, as shown in Tables 5 and 6 below.

[0106] Table 5. Uncertainty assessment of pre-calibrated conducted immunity (without adaptive impedance compensation)

[0107]

[0108]

[0109] Through impedance compensation, M VC Significant improvements can be achieved, especially with impedance matching, M VC This can reduce the testing error of the network analyzer. According to the product manual, the testing error is 0.1dB.

[0110] Table 6: Uncertainty assessment of pre-calibrated conducted immunity (including adaptive impedance compensation)

[0111]

[0112] In summary, the uncertainty was reduced by 17.9% through adaptive impedance compensation.

[0113] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An electromagnetic compatibility conducted immunity calibration system, characterized by: The calibration system comprises a signal generating module, a coupled decoupling network adaptive assembly system, a calibration load passage system, and an auxiliary equipment termination system. The signal generating module is connected to the coupled decoupling network adaptive assembly system and is configured to generate a calibrated radio frequency signal to the coupled decoupling network adaptive assembly system. The coupled decoupling network adaptive assembly system is connected to the calibration load passage system and the auxiliary equipment termination system respectively, and is configured to couple the radio frequency signal to the calibration load passage system in common mode and to shield and decouple the auxiliary equipment termination system from radio frequency. The calibration load passage system is configured to simulate a test sample and complete impedance matching to obtain a calibrated radio frequency power. The auxiliary equipment termination system is configured to simulate an auxiliary equipment environment of a product during testing. The signal generating module comprises a radio frequency signal source (101), a power amplifier (102), an attenuator (103), a radio frequency switch one (104), and a network analyzer one (105). The radio frequency signal source (101), the power amplifier (102), the attenuator (103), and the radio frequency switch one (104) are connected in sequence. The radio frequency switch one (104) is further connected to the network analyzer one (105) and the coupled decoupling network adaptive assembly system. The coupled decoupling network adaptive assembly system comprises a coupled decoupling network (201). The coupled decoupling network (201) is replaceable according to a type of a test product. The coupled decoupling network (201) is connected to the radio frequency switch one (104). The calibration load passage system comprises a common mode port merging device one (301), an impedance converter one (302), a radio frequency switch two (303), a power meter (305), an adaptive matching load (306), and a network analyzer two (307). The common mode port merging device one (301), the impedance converter one (302), and the radio frequency switch two (303) are connected in sequence. The radio frequency switch two (303) is further connected to the network analyzer two (307) and a probe (304) of the power meter (305). The adaptive matching load (306) is located on the probe (304). The probe (304) of the power meter (305) measures and records radio frequency power during calibration. The adaptive matching load (306) matches radio frequency impedance during calibration. The auxiliary equipment termination system comprises a common mode port merging device two (401), an impedance converter two (402), a radio frequency switch three (403), and a load impedance (404), which are connected in sequence. The radio frequency switch three (403) is configured to control the communication between the impedance converter two (402) and the load impedance (404).

2. An electromagnetic compatibility conducted immunity calibration system as claimed in claim 1, characterized in that: The calibration system further comprises a grounding protection system. The grounding protection system comprises a metal grounding plate (505). The coupled decoupling network adaptive assembly system, the calibration load passage system, and the auxiliary equipment termination system are located on the metal grounding plate (505). A digital multimeter (504) is arranged on the metal grounding plate (505). Probes of the digital multimeter (504) are connected to the ground and a shell of the coupled decoupling network (201) respectively.

3. A calibration method of an electromagnetic compatibility conducted immunity calibration system according to claim 2, characterized in that, It comprises the following steps: Step 1: According to the actual test target voltage, select the same size of calibration target voltage , frequency change step , ≤1%, calibration start frequency and calibration end frequency , set the current calibration frequency ; According to the actual test product power line type, select the matching coupling decoupling network (201); Step two: calculate the initial level setting value corresponding to the radio frequency signal source (101) , set the frequency of the radio frequency signal source (101) to , and the level value to ; Step three: the radio frequency signal source (101) radio frequency output port is connected to the radio frequency input port of the power amplifier (102), the radio frequency output port of the power amplifier (102) is connected to the input port of the attenuator (103), the radio frequency switch one (104) is switched to connect the network analyzer one (105), the standing wave ratio of the attenuator (103) output port is tested, if the standing wave ratio is less than 2dB, continue step four; Step four: Determine actual test product power cord electrical parameters: resistance , inductance , capacitance , Determine the electrical parameters of the output port of the coupling-decoupling network (201) that matches the type of actual test product: resistance , inductance , capacitance , by the formula: Calculate the calibrated output port RF impedance, switch RF switch one (104) to connect the coupled decoupling network (201), switch RF switch two (303) to connect network analyzer two (307), test the frequency The corresponding RF impedance, if it deviates from the calibrated output port RF impedance by less than 20%, automatic impedance matching is completed through the subsequent adaptive matching load (306), and step five continues. Step five: switch the radio frequency switch two (303) to connect the probe (304), the output port of the common mode port merging device two (401) is connected to the input port of the radio frequency switch three (403) through the impedance converter two (402), the radio frequency switch three (403) is connected to the load impedance (404), the radio frequency performance of the analog power supply is realized, and the first level value is obtained by testing the probe (304) of the power meter (305) ; Step six: If the first level value The results are in line with the range requirements, continue step seven; Step seven: disconnect the RF switch three (403) from the load impedance (404), and use the probe (304) of the power meter (305) to test the second level value ; if , select the larger result of and as the test level , record the corresponding calibration frequency , test level , calibration target voltage , signal source level , and continue to step eight; Step 8: Set the calibration frequency Adjusted to Check if the adjustment result is ≤ If yes, repeat steps two through seven; if no, end the calibration task. Step nine: Derive calibration frequencies for all calibration frequencies , test level , calibration target voltage , signal source level Form the calibration database for this calibration.

4. A calibration method of an electromagnetic compatibility conducted immunity calibration system according to claim 3, characterized in that: Before the step one, the resistance between the metal shell of the coupling decoupling network (201) and the grounding point is measured by the digital multimeter (504), if it is less than or equal to 4Ω, continue step two, if it is greater than 4Ω, check the grounding protection system until it meets the requirements, continue step one; In the step three, if the standing wave ratio is greater than or equal to 2dB, turn off the system and check whether the connection of each port of the signal generation module is normal, and repeat step two; In the step four, if the deviation is more than 20%, turn off the system to check the radio frequency connection between the signal generation system, the coupling decoupling network (201), the common mode port merging device one (301) and the impedance converter one (302), and then repeat step four until the requirements are met; If the first level value is not within the range requirement , if greater than the range requirement, the signal source level is adjusted down by 1.5dB, step five is repeated, if less than the range requirement, the signal source level is adjusted up by 1.5dB, step five is repeated, until the result meets the range requirement; In step seven, if , it is explained that the decoupling function of the coupled decoupling network (201) is degraded and the calibration check of the coupled decoupling network (201) needs to be terminated.

5. A method of calibration of an electromagnetic compatibility conducted immunity calibration system according to claim 3 or 4, characterized in that: According to the performance parameters of the tested product, the parameters and arrangement of the calibration are adjusted, and during the calibration process, the phase type of the power line is respectively adjusted, including single-phase single line, single-phase two line, single-phase three line, three-phase four line, three-phase five line, the shielding category of the power line, including shielded line and unshielded line, and the electrical parameters of the power line, including resistance, inductance and capacitance, so as to more accurately simulate the actual test scene and improve the accuracy of the calibration result; If it is an unshielded line, during the calibration process, the calibration load access system is in an unshielded state; If it is a shielded line, during the calibration process, the calibration load access system needs to be covered with a metal shielding net and connected with the metal shell of the coupling decoupling network (201) and the metal grounding plate (505), and the power meter (305) and the network analyzer two (307) are outside the metal shielding net and connected with the metal shielding net cover through the shielded line, in order to avoid short circuit, a thin layer of shielding material is added between the calibration load access system and the metal shielding net cover.

6. A calibration method of an electromagnetic compatibility conducted immunity calibration system according to claim 3 or 4, characterized in that: In the step two, the initial level setting value of the radio frequency signal source (101) is: wherein, is the initial level setting value of the radio frequency signal source (101), is the calibration target voltage, is the voltage gain of the power amplifier (102), is the voltage attenuation factor of the attenuator (103), is the output impedance of the attenuator (103), is the common mode impedance of the coupling decoupling network (201), is the conversion impedance of the impedance converter one (302), is the impedance of the adaptive matching load (306).

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