An apparatus and method for predicting common mode disturbance occupancy in a conducted disturbance voltage test

Abstract

The application provides a device and a method for predicting a common-mode disturbance proportion in a disturbance voltage test, the device comprising a high-voltage probe, a damped oscillation wave generator, a cable, an oscilloscope, a current probe and a controller; when the common-mode transfer impedance is determined, the high-voltage probe is connected with the damped oscillation wave generator; when the disturbance voltage of the measured port is measured, the measured port is connected with the high-voltage probe and the damped oscillation wave generator respectively; the controller is connected with the oscilloscope, and is used for calculating the common-mode disturbance proportion based on the measurement result of the oscilloscope. The common-mode voltage and the common-mode current in the measurement circuit are used to obtain the common-mode transfer impedance, and then the common-mode voltage proportion in the disturbance voltage of the measured port is obtained. The method can eliminate the common-mode disturbance voltage component in the port voltage, has the advantages of simple operation, easy implementation, good economy, high safety and the like, and can be widely applied to transient electromagnetic disturbance tests of power system on-site secondary equipment.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic compatibility (EMC) technology for predicting the common-mode interference ratio in transient disturbance voltage measurement at the ports of localized secondary equipment in power systems, specifically to an apparatus and method for predicting the common-mode interference ratio in disturbance voltage testing. Background Technology

[0002] Switching operations in substations, the opening and closing of primary and secondary integrated pole-mounted switches, and the switching on and off of IGBTs in converter stations all induce transient electromagnetic interference (EMI) in power systems. Currently, many secondary devices are located near primary equipment, and electromagnetic transients generate fast-damped oscillating waves with dominant frequencies (oscillation frequencies) ranging from several megahertz to tens of megahertz at the ports of these secondary devices. Numerous experimental results have shown that fast-damped oscillating waves are the primary EMI waveform experienced by localized equipment in power systems during switching operations. Therefore, for EMI immunity testing of nearby secondary equipment under switching operation conditions in power systems, fast-damped oscillating wave tests at oscillation frequencies of 3MHz, 10MHz, and 30MHz are necessary. These three frequencies, as typical points, can essentially cover the oscillation frequency range from several MHz to tens of MHz.

[0003] Electromagnetic interference can be conducted from the primary side to the secondary side cable through voltage and current transformers, and then coupled to the ports of secondary equipment.

[0004] On the other hand, electromagnetic interference can also couple to the ports of secondary equipment through field line coupling in the spatial field. Electromagnetic interference can cause abnormal operation or even damage to electronic and electrical equipment. In real-world scenarios, the electromagnetic environment is complex and harsh, making it difficult and time-consuming to obtain electromagnetic interference characteristics solely through simulation calculations.

[0005] Therefore, it is often necessary to obtain the transient interference voltage generated at the secondary equipment port by the switching operation through on-site measurement. In actual testing, there is an issue that affects the accuracy of the measurement results: spatial electromagnetic interference, ground loop interference, etc., can also affect the measurement system.

[0006] For example, a spatial electromagnetic field induces a common-mode current in a coaxial cable, which is then converted into a differential-mode voltage on the oscilloscope input channel based on transfer impedance, and superimposed on the voltage of the port under test. Ground loop interference refers to the circulating current caused by the spatial field or ground potential difference in the loop formed by the coaxial cable shield-ground-grounding wire or parasitic circuit parameters to ground. In comparison, the common-mode current mainly flows along the shield and returns through an external path of the cable (such as the earth or grounding grid), while the differential-mode current flows along the loop between the coaxial cable core and the shield. To accurately determine the actual voltage of the port under test, it is necessary to eliminate the common-mode interference voltage component caused by the common-mode current in the cable shield during testing.

[0007] However, it is currently impossible to accurately predict the common-mode interference ratio of a circuit under the action of fast damped oscillating waves. Summary of the Invention

[0008] To address the problem of predicting the common-mode voltage ratio in transient disturbance voltages generated at secondary equipment ports in power systems, this invention proposes a measurement device for predicting the common-mode disturbance ratio in disturbance voltage testing, comprising: a high-voltage probe, a damped oscillating wave generator, a cable, an oscilloscope, a current probe, and a controller.

[0009] When the common-mode transfer impedance is determined, one end of the high-voltage probe is connected to the damped oscillating wave generator, and the other end is connected to channel 1 of the oscilloscope through the cable.

[0010] One end of the current probe is connected to the cable, and the other end is connected to channel 2 of the oscilloscope; at the same time, the oscilloscope is connected to the damped oscillating wave generator; channel 1 and channel 2 of the oscilloscope are used to measure the common-mode voltage and common-mode current in the circuit, respectively.

[0011] When measuring the interference voltage of the port under test, the port under test is connected to one end of the high voltage probe and the damped oscillation wave generator respectively; the other end of the high voltage probe is connected to channel 1 of the oscilloscope through a cable;

[0012] One end of the current probe is connected to the cable, and the other end is connected to channel 2 of the oscilloscope; at the same time, the oscilloscope is connected to the damped oscillation wave generator; channel 1 and channel 2 of the oscilloscope are used to measure the port voltage and actual common-mode current of the port under test, respectively.

[0013] The controller is connected to the oscilloscope and is used to calculate the common-mode interference ratio based on the common-mode voltage, common-mode current, port voltage, and actual common-mode current.

[0014] Preferably, when the common-mode transfer impedance is determined, the positive and negative terminals of the primary side of the high-voltage probe are short-circuited and connected to the positive terminal of the damped oscillating wave generator, and the secondary side of the high-voltage probe is connected to one end of the cable.

[0015] The other end of the cable is connected to channel 1 of the oscilloscope;

[0016] The clamp of the current probe is connected to the cable, and the clamp is close to the connection between the cable and channel 1 of the oscilloscope. The output end of the current probe is connected to channel 2 of the oscilloscope. At the same time, the housing of the oscilloscope is connected to the negative terminal of the damped oscillation wave generator, and the housing is grounded.

[0017] Preferably, when measuring the interference voltage of the port under test, the positive and negative terminals of the port under test are connected to the positive and negative terminals of the primary side of the high voltage probe and the positive and negative terminals of the damped oscillation wave generator, respectively.

[0018] The secondary side of the high-voltage probe is connected to one end of the cable; the other end of the cable is connected to channel 1 of the oscilloscope.

[0019] The clamp of the current probe is connected to the cable, and the clamp is close to the connection between the cable and channel 1 of the oscilloscope. The output end of the current probe is connected to channel 2 of the oscilloscope. At the same time, the housing of the oscilloscope is connected to the negative terminal of the damped oscillation wave generator, and the housing is grounded.

[0020] Preferably, it also includes a metal plate and wires, wherein the negative terminal of the damped oscillating wave generator and the housing of the oscilloscope are respectively connected to the metal plate through the wires, and the metal plate is grounded.

[0021] Preferably, the metal plate comprises an aluminum plate.

[0022] Preferably, it also includes a protective resistor, one end of which is connected to the housing of the oscilloscope and the other end of which is connected to the metal plate.

[0023] Based on the same inventive concept, this invention also proposes a method for predicting the common-mode interference ratio in interference voltage testing, utilizing the controller in the measuring device provided by this invention. The method includes:

[0024] The common-mode voltage and common-mode current in the common-mode transfer impedance test circuit are measured using the aforementioned measuring device;

[0025] The port voltage and actual common-mode current of the port under test are measured using the measuring device.

[0026] The common-mode interference ratio is calculated based on the common-mode voltage, common-mode current, port voltage, and actual common-mode current.

[0027] Preferably, the calculation of the common-mode interference ratio based on the common-mode voltage, common-mode current, port voltage, and actual common-mode current includes:

[0028] The common-mode transfer impedance is obtained from the ratio of the common-mode voltage to the common-mode current. The common-mode interference voltage of the port under test is obtained from the product of the common-mode transfer impedance and the actual common-mode current. The common-mode interference ratio is obtained from the ratio of the common-mode interference voltage to the port voltage.

[0029] Preferably, the method further includes:

[0030] Based on the common-mode interference ratio, the common-mode interference voltage component caused by the common-mode current in the cable shield is removed to obtain the actual voltage of the port under test.

[0031] Based on the same inventive concept, this invention also proposes a prediction system for the common-mode voltage ratio in interference voltage testing. Using the measuring device provided by this invention, the prediction system includes:

[0032] A common-mode transfer impedance module is used to obtain common-mode voltage and common-mode current using the measuring device.

[0033] The measured port module is used to measure the port voltage and actual common-mode current of the measured port using the measuring device.

[0034] The prediction module is used to calculate the common-mode interference ratio based on the common-mode voltage, common-mode current, port voltage, and actual common-mode current.

[0035] Preferably, the prediction module includes a common-mode transfer impedance calculation unit, a common-mode interference voltage calculation unit, and a percentage calculation unit;

[0036] The common-mode transfer impedance unit is used to calculate the common-mode transfer impedance based on the common-mode voltage and common-mode current. The common-mode interference voltage calculation unit is used to calculate the common-mode interference voltage based on the common-mode transfer impedance and the actual common-mode current. The proportion calculation unit is used to calculate the common-mode interference proportion based on the common-mode interference voltage and the port voltage.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] (1) The present invention provides a measuring device for predicting the common-mode interference ratio in interference voltage testing, comprising a high-voltage probe, a damped oscillating wave generator, a cable, an oscilloscope, and a current probe. When determining the common-mode transfer impedance, the high-voltage probe is connected to the damped oscillating wave generator, and the common-mode voltage and common-mode current in the circuit are measured through channels 1 and 2 of the oscilloscope, respectively, to obtain the common-mode transfer impedance. When measuring the interference voltage of the port under test, the port under test is connected to both the high-voltage probe and the damped oscillating wave generator, and the port voltage and actual common-mode current of the port under test are measured through channels 1 and 2 of the oscilloscope, respectively, to obtain the common-mode interference voltage and its ratio. This measuring device is simple to operate and easy to implement, and can accurately measure the port voltage and common-mode current of the port under test, thereby obtaining the common-mode interference voltage in the port voltage.

[0039] (2) The present invention provides a method for predicting the common-mode interference ratio in disturbance voltage testing. This method uses a common-mode voltage measuring device to obtain the common-mode transfer impedance and measures the port voltage and actual common-mode current of the port under test, thereby obtaining the common-mode disturbance voltage and the common-mode voltage ratio within the port voltage. This prediction method can eliminate common-mode disturbance voltage in disturbance voltage testing, accurately determine the actual voltage of the port under test, and is simple to operate and easy to implement. It can be widely applied to transient electromagnetic interference testing of local secondary equipment in power systems. Attached Figure Description

[0040] Figure 1 The present invention provides a method for obtaining common-mode current i c 'and common-mode voltage U c A wiring diagram illustrating the transformation relationship of ';

[0041] Figure 2 A wiring diagram for obtaining the port voltage U and common-mode current i of the measured port provided by the present invention;

[0042] Figure 3 This is a flowchart illustrating the method for predicting the common-mode voltage ratio in disturbance voltage testing provided by the present invention. Detailed Implementation

[0043] Example 1:

[0044] This invention discloses a measuring device for measuring the common-mode voltage ratio in disturbance voltage testing, comprising: a high-voltage probe, a damped oscillating wave generator, a cable, an oscilloscope, a current probe, and a controller.

[0045] like Figure 1 As shown, the damped oscillating wave generator is used to simulate interference sources. When the common-mode transfer impedance, which represents the conversion relationship between common-mode voltage and common-mode current, is determined, the positive and negative terminals of the primary side of the high-voltage probe are short-circuited and connected to the positive terminal of the damped oscillating wave generator. The secondary side of the high-voltage probe is connected to channel 1 of the oscilloscope via a cable. The clamp of the current probe is connected to the lead at the connection between the cable and channel 1 of the oscilloscope, and the output terminal of the current probe is connected to channel 2 of the oscilloscope. At the same time, the casing of the oscilloscope is connected to the negative terminal of the damped oscillating wave generator, and the casing of the oscilloscope is grounded.

[0046] At this point, the primary side of the high-voltage probe can be considered entirely common-mode voltage. Considering that the high-voltage wall impedance of the high-voltage probe is much greater than the low-voltage wall impedance, and the oscilloscope input impedance is also very large, approximately 1 MΩ, the current in the cable mainly occurs in the shielding layer, while the core wire current can be ignored. Therefore, the voltage measured by oscilloscope channel 1 is mainly the common-mode voltage U caused by the common-mode current in the shielding layer. cSimultaneously, the output signal of the current probe serves as the input signal for oscilloscope channel 2, allowing oscilloscope channel 2 to measure the common-mode current i. c The common-mode transfer impedance can be calculated using the following formula, and the common-mode transfer impedance can represent the conversion relationship between common-mode voltage and common-mode current.

[0047] Z c =U c ' / i c '

[0048] Among them, Z c For common-mode transfer impedance, U c ' is the common-mode voltage, i c 'This represents the common-mode current.

[0049] The current probe should be placed on the cable near the oscilloscope channel 1 input, and not arbitrarily anywhere on the cable. This is because it allows for the full impact of all common-mode effects along the cable on the common-mode current at the port. Furthermore, in real-world environments, due to the high frequency of fast-damped oscillating waves, cable lengths can sometimes exceed one-tenth of the wavelength, such as cables typically 1 to 3 meters long. In such cases, the distributed parameters or transmission line effects along the cable are significant, and the common-mode current is not uniformly distributed. Testing the common-mode current near the oscilloscope channel 1 input avoids the common-mode transfer impedance Z caused by this unknown current non-uniform distribution. c Uncertainty.

[0050] like Figure 2 As shown, when measuring the voltage of the port under test, the positive and negative terminals of the port under test are connected to the positive and negative terminals of the primary side of the high-voltage probe, respectively. Simultaneously, the positive and negative terminals of the port under test are also connected to the positive and negative terminals of the damped oscillating wave generator, respectively. The secondary side of the high-voltage probe is connected to channel 1 of the oscilloscope via a cable. The clamp of the current probe is connected to the lead at the connection point between the cable and channel 1 of the oscilloscope, and the output terminal of the current probe is connected to channel 2 of the oscilloscope. At the same time, the oscilloscope casing is connected to the negative terminal of the damped oscillating wave generator, and the oscilloscope casing is grounded. At this time, the port voltage and actual common-mode current of the port under test can be measured using channels 1 and 2 of the oscilloscope, respectively.

[0051] The controller is connected to the oscilloscope, and the data measured by the oscilloscope can be transmitted to the controller. The controller can then be used to calculate the common-mode interference ratio of the port under test. Specifically, the common-mode transfer impedance is calculated from the ratio of the common-mode voltage to the common-mode current. The common-mode interference voltage of the port under test is calculated from the product of the common-mode transfer impedance and the actual common-mode current. Finally, the common-mode interference ratio is obtained from the ratio of the common-mode interference voltage to the port voltage.

[0052] This measuring device can ground the oscilloscope's casing via a grounded metal plate. Specifically, the negative terminal of the damped oscillator generator and the oscilloscope's casing are connected to the metal plate via wires, and the metal plate is grounded. The metal plate can be made of steel, aluminum, etc. A protective resistor can also be connected in series in the measuring device. For example, one end of the protective resistor can be connected to the oscilloscope's casing via a wire, and the other end can be connected to the metal plate via a wire. The protective resistor can improve the safety of the measuring device.

[0053] This measuring device can simultaneously acquire the common-mode transfer impedance and the actual common-mode current of the port under test, thereby obtaining the common-mode interference voltage in the port voltage and accurately determining the proportion of common-mode interference voltage at the port under test. The device only requires connecting a current probe capable of measuring transient current to one channel input of the oscilloscope in the measurement system. Simultaneously, it utilizes two channels of the oscilloscope to measure the common-mode voltage and common-mode current respectively. It is simple to operate, low in cost, and highly safe, making it suitable for widespread application in measurement scenarios for localized equipment such as substations.

[0054] Example 2:

[0055] This invention discloses a method for predicting the common-mode voltage ratio in interference voltage testing. It utilizes the conversion relationship between common-mode current and common-mode voltage to evaluate the common-mode interference voltage experienced by the test system, such as... Figure 3 As shown, the common-mode transfer impedance is first obtained using a common-mode voltage measurement device. Then, the common-mode interference voltage at the port under test is determined using the common-mode voltage measurement device and the common-mode transfer impedance. Finally, the common-mode voltage ratio at the port under test is obtained based on the common-mode interference voltage and the port voltage. The following is a detailed explanation of this prediction method.

[0056] This causes the fast damped oscillating wave generator OCS 00N6FX to output voltage U s The common-mode interference ratio was calculated at 1350V, 3MHz, 10MHz and 30MHz respectively.

[0057] Step 1: Obtain the conversion relationship between common-mode current and common-mode voltage at the oscilloscope port under the action of a fast damped oscillating wave in the laboratory.

[0058] like Figure 1 As shown, a fast damped oscillator is used to simulate an actual interference source. The positive and negative terminals of the primary side of the high-voltage probe are short-circuited and connected to the positive terminal of the fast damped oscillator. The negative terminal of the fast damped oscillator and the oscilloscope casing are both connected to a metal plate and grounded through short wires. The secondary side of the high-voltage probe is connected to channel 1 of the oscilloscope via a coaxial cable. The common-mode voltage U can be measured. cThe current probe's clamp is attached to the lead of the coaxial cable on the secondary side of the high-voltage probe. This lead is located near the input port of oscilloscope channel 1, and the output of the current probe is connected to oscilloscope channel 2. In this embodiment, the high-voltage probe is a Pinzhi P6010A, the coaxial cable is a 2m long BNC coaxial cable, the oscilloscope is a RIGOL MSO5204 digital oscilloscope, the current probe is a Pearson clamp-type current probe, and the metal plate is a 1mm thick aluminum plate.

[0059] The peak value displayed on the oscilloscope was recorded, and the measurement data is shown in Table 1.

[0060] Table 1. Common-mode voltage and common-mode current measurement data

[0061]

[0062] The measured common-mode voltage and common-mode current are transmitted to the controller, which then calculates the common-mode transfer impedance Z using the following formula. c Common-mode transfer impedance Z c It is used to represent the conversion relationship between common-mode current and common-mode voltage.

[0063] Z c =U c ' / i c '

[0064] Among them, Z c For common-mode transfer impedance, U c ' is the common-mode voltage, taken as the peak-to-peak value, i c 'This represents the common-mode current, and the peak-to-peak value is taken. The calculation results of the common-mode transfer impedance are shown in Table 2.

[0065] Table 2 Calculation results of common-mode transfer impedance

[0066]

[0067] The test results show that the common-mode transfer impedance is relatively stable and has good repeatability.

[0068] Step 2: Measure the port voltage U and the actual common-mode current i of the port under test on site.

[0069] like Figure 2 As shown, the primary side of the high-voltage probe and the fast-damped oscillator are connected to the port under test, respectively. The secondary side of the high-voltage probe is connected to channel 1 of the oscilloscope via a coaxial cable. The clamp of the current probe is clamped on the lead of the coaxial cable near channel 1 of the oscilloscope. The output end of the current probe is connected to channel 2 of the oscilloscope.

[0070] After applying an interference source using a fast-damped oscillating wave generator, the oscilloscope displays a waveform. At this time, the displayed voltage of channel 1 of the oscilloscope is the port voltage U of the measured port. The output signal of the current probe serves as the input signal of channel 2 of the oscilloscope. Therefore, channel 2 of the oscilloscope can measure the actual common-mode current i. The peak value displayed by the oscilloscope is recorded, and the measurement data is shown in Table 3.

[0071] Table 3. Measurement data of port voltage U and actual common-mode current i

[0072]

[0073] Step 3: Obtain the common-mode interference voltage U in the port voltage U. c And calculate the common-mode voltage percentage.

[0074] The measured port voltage and actual common-mode current are transmitted to the controller, which then calculates the common-mode interference voltage using the following formula:

[0075] U c =i×Z c

[0076] Among them, U c Z represents the common-mode interference voltage, i represents the actual common-mode current, and Z represents the common-mode current. c This is the common-mode transfer impedance. U c The calculation results are shown in Table 4.

[0077] Table 4 Calculation results of common-mode interference voltage

[0078]

[0079] The common-mode voltage percentage in the port voltage is calculated using the following formula:

[0080] R = (U c / U)×100%

[0081] Where R is the percentage of common-mode voltage in the port voltage, U c Let U be the common-mode interference voltage, and U be the port voltage of the port under test. The calculated common-mode voltage percentage data are shown in Table 5.

[0082] Table 5 Common-mode voltage percentage results

[0083]

[0084] It can be seen that the actual common-mode current i measured on-site is significantly different from the common-mode current i measured during interference testing in the laboratory. c 'Smaller, i is in the milliampere range, i cThe magnitude of the common-mode voltage is in the ampere range, and it can be seen that the percentage of common-mode interference that may be converted into differential-mode voltage is relatively small. This indicates that the proportion of common-mode interference at the voltage port under test is very small, and the error introduced by the measurement system can be ignored. The experimental results mainly depend on the test environment and the test sample. The data in Table 5 also show that the proportion of common-mode voltage increases with the increase of the oscillation frequency of the fast damped oscillator. When the oscillation frequency is 30MHz, the proportion of common-mode voltage is 2.56%, which is equivalent to 18 times the proportion of common-mode voltage when the oscillation frequency is 3MHz.

[0085] Based on the calculated common-mode interference ratio, the common-mode interference voltage component caused by the common-mode current in the cable shield can be eliminated, thereby obtaining the actual voltage of the port under test.

[0086] The output voltage U of the fast damped oscillating wave generator OCS 00N6FX s Set the voltage to 1800V and repeat the above test process to obtain U. s The common-mode interference percentages at 1800V and frequencies of 3MHz, 10MHz, and 30MHz are respectively.

[0087] Output voltage U s After the voltage increase, the measured data of common-mode voltage and common-mode current are shown in Table 6, and the measured data of port voltage and actual common-mode current are shown in Table 8. The measured common-mode voltage, common-mode current, port voltage, and actual common-mode current are transmitted to the controller, which calculates the common-mode transfer impedance, common-mode interference voltage, and common-mode interference voltage percentage. The calculation results of the common-mode transfer impedance are shown in Table 7, the calculation results of the common-mode interference voltage are shown in Table 9, and the calculation results of the common-mode voltage percentage are shown in Table 10.

[0088] Table 6. Common-mode voltage and common-mode current measurement data

[0089]

[0090] Table 7 Calculation results of common-mode transfer impedance

[0091]

[0092] Table 8. Measurement data of port voltage and actual common-mode current.

[0093]

[0094] Table 9 Calculation results of common-mode interference voltage

[0095]

[0096] Table 10 Calculation results of common-mode voltage percentage

[0097]

[0098] Similarly, based on the calculated common-mode interference ratio, the output voltage U of the fast damped oscillator OCS00N6FX can be excluded. s The common-mode interference voltage component caused by the common-mode current in the cable shield at 1800V is used to obtain the actual voltage of the port under test.

[0099] The predicted results of the two common-mode voltage ratios show good repeatability. Further analysis reveals that the magnitude of the source's output voltage has a relatively small impact on the common-mode interference ratio, while the source's output frequency has a significant impact. The stray capacitance and inductance between the coaxial cable shield and the ground loop are functions of frequency, not voltage, which also explains this phenomenon.

[0100] This prediction method uses the measuring device provided in Example 1 to obtain the conversion relationship between common-mode voltage and common-mode current, as well as the port voltage and actual common-mode current of the port under test. It then obtains the common-mode voltage component and its proportion of the port under test. This method can be used to remove the common-mode interference component in the port voltage measurement results. It has the advantages of simple operation, easy implementation, and good economy. It can be widely used in transient electromagnetic interference testing of local secondary equipment in power systems.

[0101] It should be noted that the common-mode component accounts for a relatively small proportion in the above test results because the electromagnetic environment in laboratory tests is relatively simple and clean. In test sites such as substations, strong transient electromagnetic fields caused by high voltage and high current exist, and the proportion of common-mode interference voltage may be significantly greater than the results shown above.

[0102] Furthermore, the oscillation frequency of the damped oscillation wave in actual field conditions cannot be exactly 3MHz, 10MHz, or 30MHz. One approach is to generate a damped oscillation wave with the same frequency as the field oscillation in the laboratory using a programmable signal generator and then test the common-mode current and common-mode transfer impedance. An alternative approach is to obtain the common-mode transfer impedance at other oscillation frequencies by linearly fitting the results of the common-mode transfer impedance at 3MHz, 10MHz, or 30MHz.

[0103] Example 3:

[0104] This invention discloses a prediction system for the common-mode voltage ratio in interference voltage testing. The system includes: a common-mode transfer impedance module for measuring the common-mode voltage and common-mode current in a circuit that determines the common-mode transfer impedance using a measuring device; a measured port module for measuring the port voltage and actual common-mode current of the measured port in the interference voltage testing circuit using a measuring device; and a prediction module for calculating the common-mode interference ratio based on the common-mode voltage, common-mode current, port voltage, and actual common-mode current.

[0105] The prediction module includes a common-mode transfer impedance calculation unit, a common-mode interference voltage calculation unit, and a percentage calculation unit;

[0106] The common-mode transfer impedance calculation unit is used to obtain the common-mode transfer impedance from the ratio of the measured common-mode voltage to the common-mode current. The common-mode disturbance voltage calculation unit is used to obtain the common-mode disturbance voltage from the product of the common-mode transfer impedance and the actual common-mode current. The proportion calculation unit is used to obtain the common-mode disturbance proportion in the disturbance voltage test circuit from the ratio of the common-mode disturbance voltage to the port voltage.

[0107] The measuring devices used in this system include: a high-voltage probe, a damped oscillating wave generator, cables, an oscilloscope, a current probe, and a controller. For example... Figure 1 As shown, the damped oscillator is used to simulate an interference source. When the common-mode transfer impedance, used to represent the conversion relationship between common-mode voltage and common-mode current, is determined, the primary side of the high-voltage probe is short-circuited between its positive and negative terminals and connected to the positive terminal of the damped oscillator. The secondary side of the high-voltage probe is connected to channel 1 of the oscilloscope via a cable. The clamp of the current probe is connected to the lead at the connection point between the cable and channel 1 of the oscilloscope, and the output terminal of the current probe is connected to channel 2 of the oscilloscope. Simultaneously, the oscilloscope casing is connected to the negative terminal of the damped oscillator, and the oscilloscope casing is grounded. At this time, the common-mode voltage and common-mode current can be measured from channels 1 and 2 of the oscilloscope, respectively. Figure 2 As shown, when measuring the voltage of the port under test, the positive and negative terminals of the port under test are connected to the positive and negative terminals of the primary side of the high-voltage probe, respectively. Simultaneously, the positive and negative terminals of the port under test are also connected to the positive and negative terminals of the damped oscillating wave generator, respectively. The secondary side of the high-voltage probe is connected to channel 1 of the oscilloscope via a cable. The clamp of the current probe is connected to the lead at the connection point between the cable and channel 1 of the oscilloscope, and the output terminal of the current probe is connected to channel 2 of the oscilloscope. Simultaneously, the oscilloscope casing is connected to the negative terminal of the damped oscillating wave generator, and the oscilloscope casing is grounded. At this time, the port voltage and actual common-mode current of the port under test can be measured using channels 1 and 2 of the oscilloscope, respectively. The controller is connected to the oscilloscope to read the measurement results and calculate the common-mode interference ratio from the common-mode voltage, common-mode current, port voltage, and actual common-mode current measured by the oscilloscope. Specifically, the common-mode transfer impedance is calculated from the ratio of common-mode voltage to common-mode current. The common-mode interference voltage at the port under test is calculated from the product of the common-mode transfer impedance and the actual common-mode current. The common-mode interference ratio is then obtained from the ratio of the common-mode interference voltage to the port voltage.

[0108] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0109] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0110] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0111] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0112] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A measuring device for predicting the proportion of common-mode interference in interference voltage testing, characterized in that, include: High voltage probe, damped oscillating wave generator, cable, oscilloscope, current probe and controller; When the common-mode transfer impedance is determined, one end of the high-voltage probe is connected to the damped oscillating wave generator, and the other end is connected to channel 1 of the oscilloscope through the cable. One end of the current probe is connected to the cable, and the other end is connected to channel 2 of the oscilloscope; at the same time, the oscilloscope is connected to the damped oscillating wave generator; channel 1 and channel 2 of the oscilloscope are used to measure the common-mode voltage and common-mode current in the circuit, respectively. When measuring the interference voltage of the port under test, the port under test is connected to one end of the high voltage probe and the damped oscillation wave generator respectively; the other end of the high voltage probe is connected to channel 1 of the oscilloscope through a cable; One end of the current probe is connected to the cable, and the other end is connected to channel 2 of the oscilloscope; at the same time, the oscilloscope is connected to the damped oscillation wave generator; channel 1 and channel 2 of the oscilloscope are used to measure the port voltage and actual common-mode current of the port under test, respectively. The controller is connected to the oscilloscope and is used to calculate the common-mode interference ratio based on the common-mode voltage, common-mode current, port voltage, and actual common-mode current.

2. The measuring device as described in claim 1, characterized in that, When the common-mode transfer impedance is determined, the positive and negative terminals of the primary side of the high-voltage probe are short-circuited and connected to the positive terminal of the damped oscillating wave generator, and the secondary side of the high-voltage probe is connected to one end of the cable. The other end of the cable is connected to channel 1 of the oscilloscope; The clamp of the current probe is connected to the cable, and the clamp is close to the connection between the cable and channel 1 of the oscilloscope. The output end of the current probe is connected to channel 2 of the oscilloscope. At the same time, the housing of the oscilloscope is connected to the negative terminal of the damped oscillation wave generator, and the housing is grounded.

3. The measuring device as described in claim 2, characterized in that, When measuring the interference voltage of the port under test, the positive and negative terminals of the port under test are connected to the positive and negative terminals of the primary side of the high voltage probe and the positive and negative terminals of the damped oscillation wave generator, respectively. The secondary side of the high-voltage probe is connected to one end of the cable; the other end of the cable is connected to channel 1 of the oscilloscope. The clamp of the current probe is connected to the cable, and the clamp is close to the connection between the cable and channel 1 of the oscilloscope. The output end of the current probe is connected to channel 2 of the oscilloscope. At the same time, the housing of the oscilloscope is connected to the negative terminal of the damped oscillation wave generator, and the housing is grounded.

4. The measuring device as described in claim 2 or claim 3, characterized in that, It also includes a metal plate and wires, the negative terminal of the damped oscillating wave generator and the housing of the oscilloscope are respectively connected to the metal plate through the wires, and the metal plate is grounded.

5. The measuring device as described in claim 4, characterized in that, The metal plate includes an aluminum plate.

6. The measuring device as described in claim 4, characterized in that, It also includes a protective resistor, one end of which is connected to the casing of the oscilloscope and the other end of which is connected to the metal plate.

7. A method for predicting the proportion of common-mode interference in interference voltage testing, characterized in that, The method, applied to the controller included in the measuring device according to any one of claims 1-6, comprises: The common-mode voltage and common-mode current in the circuit that determines the common-mode transfer impedance are measured using the aforementioned measuring device; The measuring device is used to measure the port voltage and actual common-mode current of the port under test in the interference voltage test circuit. The common-mode interference ratio is calculated based on the common-mode voltage, common-mode current, port voltage, and actual common-mode current.

8. The prediction method as described in claim 7, characterized in that, The common-mode interference ratio calculated based on the common-mode voltage, common-mode current, port voltage, and actual common-mode current includes: The common-mode transfer impedance is obtained from the ratio of the common-mode voltage to the common-mode current. The common-mode interference voltage in the interference voltage test circuit is obtained from the product of the common-mode transfer impedance and the actual common-mode current. The common-mode interference ratio is obtained from the ratio of the common-mode interference voltage to the port voltage.

9. The prediction method as described in claim 7, characterized in that, The method further includes: Based on the common-mode interference ratio, the common-mode interference voltage component caused by the common-mode current in the cable shield is removed to obtain the actual voltage of the port under test.

10. A prediction system for the common-mode voltage ratio in disturbance voltage testing, characterized in that, The prediction system, using the measuring apparatus according to any one of claims 1-6, comprises: A common-mode transfer impedance module is used to measure the common-mode voltage and common-mode current in the circuit that determines the common-mode transfer impedance using the measuring device. The measured port module is used to measure the port voltage and actual common-mode current of the measured port in the interference voltage test circuit using the measuring device. The prediction module is used to calculate the common-mode interference ratio based on the common-mode voltage, common-mode current, port voltage, and actual common-mode current.

11. The prediction system as described in claim 10, characterized in that, The prediction module includes a common-mode transfer impedance calculation unit, a common-mode disturbance voltage calculation unit, and a percentage calculation unit. The common-mode transfer impedance calculation unit is used to calculate the common-mode transfer impedance based on the common-mode voltage and common-mode current. The common-mode interference voltage calculation unit is used to calculate the common-mode interference voltage based on the common-mode transfer impedance and the actual common-mode current. The proportion calculation unit is used to calculate the common-mode interference proportion based on the common-mode interference voltage and the port voltage.

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