Method for evaluating radiation emission level of power electronic equipment based on reverberation chamber

Abstract

The invention discloses a power electronic equipment radiation emission level evaluation method and device based on a reverberation chamber, a medium and equipment. The method comprises the following steps: acquiring a reverberation chamber radiation receiving power sample and a transmission coefficient sample; obtaining a radiation power calculation model of the to-be-tested power electronic equipment, constructing a radiation power function of the to-be-tested power electronic equipment, and obtaining a probability density function of a radiation power estimation value and an uncertainty model based on the radiation power function of the to-be-tested power electronic equipment; evaluating a first radiation emission level of the to-be-tested power electronic equipment based on the radiation power calculation model and the uncertainty model; the second radiation emission level is determined according to the radiation power function of the power electronic equipment to be measured, so that the statistical distribution characteristics of the electromagnetic field in the reverberation chamber can be accurately described, and the influence of the independent sampling number on the measurement uncertainty can be quantitatively analyzed; effective evaluation of statistical characteristics and measurement uncertainty of radiation emission of power electronic equipment is realized.

Description

Technical Field

[0001] The present application relates to the technical fields of electromagnetic compatibility testing and reverberation chamber technology, and particularly relates to a method, device, medium, and equipment for evaluating the radiation emission level of power electronic equipment based on a reverberation chamber. Background Art

[0002] With the rapid development of power electronics technology, power electronic equipment is increasingly widely used in various fields such as industry, transportation, energy, and household appliances. During the actual working process, due to the combined effects of multiple factors such as the frequent switching actions of power devices, the parasitic effects of internal circuits, and the coupling paths between magnetic components, rich high-frequency harmonic components are usually generated in the circuit. These high-frequency harmonic components will radiate outward in the form of electromagnetic waves through various channels such as current loops, long wires, and radiators in the circuit, interfering with surrounding electronic equipment, affecting its normal operation, and even threatening the reliability and safety of the entire power electronic system. Therefore, accurate and effective radiation emission testing of power electronic equipment to evaluate its electromagnetic radiation characteristics is a necessary prerequisite for ensuring the stable and reliable operation of electronic equipment.

[0003] Currently, domestic reverberation chamber-related standards for the radiation emission testing of electronic equipment, such as GB / T 9254.1, usually only set fixed limits for the radiation emission in specific frequency bands, while ignoring the inherent statistical characteristics of reverberation chamber testing and their impact on test results. In reverberation chamber electromagnetic compatibility testing, the test results of radiation emission have specific statistical characteristics and are not a single fixed value. In addition, the size of the independent sample number has a significant impact on the measurement uncertainty of statistical measurements. Therefore, simply comparing one or several measurement values with fixed limits is difficult to accurately evaluate the actual radiation emission level of the equipment and cannot effectively predict its electromagnetic compatibility performance in the actual working electromagnetic environment.

[0004] The existing radiation emission reverberation chamber testing and risk assessment methods have at least the following deficiencies:

[0005] The current reverberation chamber testing method for radiation emission lacks an accurate statistical theory model, so it is impossible to conduct a systematic analysis of the uncertainty of measurement results and it is difficult to effectively evaluate the reliability of measurement results. At the same time, the existing testing methods ignore the inherent statistical characteristics of reverberation chamber testing and the influence of the independent sample number on measurement uncertainty, resulting in a significant increase in the risk of misjudgment of whether the radiation emission meets the limits. Therefore, when using the existing methods to evaluate the radiation emission of power electronic equipment, the accuracy and reliability of the test results are significantly insufficient, which may lead to misjudgment of the electromagnetic compatibility performance of the equipment and is not conducive to product quality control and design optimization. Summary of the Invention

[0006] The main purpose of this application is to provide a method, device, medium and equipment for evaluating the radiation emission level of power electronic equipment based on a reverberation chamber, aiming to solve the technical problems of lacking an accurate statistical theory model, being unable to conduct a systematic analysis of the uncertainty of measurement results, and being difficult to effectively evaluate the reliability of measurement results.

[0007] To achieve the above object, this application provides a method for evaluating the radiation emission level of power electronic equipment based on a reverberation chamber, including: obtaining a reverberation chamber radiation reception power sample and a transmission coefficient sample; obtaining a radiation power calculation model of the power electronic equipment to be measured, wherein the power radiation function has a quadratic parameter of the absolute value of the transmission coefficient and a reception power parameter, and the quadratic parameter of the absolute value of the transmission coefficient follows an exponential distribution of a first parameter, and the reception power parameter follows an exponential distribution of a second parameter; using the transmission coefficient sample, the reception power sample and their respective sample numbers to construct a first random variable and a second random variable respectively, constructing a radiation power function of the power electronic equipment to be measured according to the first random variable, the second random variable, the first parameter and the second parameter, obtaining a probability density function of a radiation power estimate value based on the radiation power function of the power electronic equipment to be measured, and determining a relative uncertainty model based on the probability density function of the radiation power estimate value, and evaluating a first radiation emission level of the power electronic equipment to be measured based on the radiation power calculation model and the uncertainty model; determining a confidence upper limit of the radiation emission of the power electronic equipment to be measured according to the radiation power function of the power electronic equipment to be measured, and evaluating a second radiation emission level of the power electronic equipment to be measured according to the confidence upper limit.

[0008] Optionally, before using the transmission coefficient sample, the reception power sample and their respective sample numbers to construct a first random variable and a second random variable respectively, the method further includes: judging the independence of the transmission coefficient sample and the reception power sample according to the magnitude of the first-order autocorrelation coefficient of each of the transmission coefficient sample / reception power sample.

[0009] Optionally, judging the independence of the transmission coefficient sample and the reception power sample according to the magnitude of the first-order autocorrelation coefficient of each of the transmission coefficient sample / reception power sample includes: calculating the first-order autocorrelation coefficient of the transmission coefficient sample generated by the turntable; calculating the first-order autocorrelation coefficient of the transmission coefficient sample generated by the mechanical stirrer; judging whether the sample is independent according to the magnitude relationship between the first-order autocorrelation coefficient and a preset threshold, wherein judging whether the sample is independent means that if the first-order autocorrelation coefficient is less than the preset threshold, the sample is considered independent, and conversely, if the first-order autocorrelation coefficient is greater than the preset threshold, the sample is considered not independent.

[0010] Optionally, constructing a first random variable and a second random variable respectively by using the transmission coefficient samples, the received power samples, and their respective sample numbers, and constructing a radiation power function of the power electronic device under test according to the first random variable, the second random variable, the first parameter, and the second parameter includes: obtaining the first random variable based on the product of the sum of the squares of the transmission coefficient samples and the number of the transmission coefficient samples; obtaining the second random variable based on the product of the sum of the received power samples and the number of the received power samples; obtaining a first chi-square distribution based on the product of the first random variable and the first parameter; obtaining a second chi-square distribution based on the product of the second random variable and the second parameter; and rewriting a radiation power calculation model based on the first chi-square distribution and the second chi-square distribution to obtain the radiation power function of the power electronic device under test.

[0011] Optionally, determining a relative uncertainty model based on the probability density function of the radiation power estimate includes: determining the expectation of the radiation power and the variance of the radiation power according to the probability density function of the radiation power estimate; and determining the relative uncertainty model based on the expectation of the radiation power and the variance of the radiation power.

[0012] Optionally, determining the upper confidence limit of the radiation emission of the power electronic device under test according to the radiation power function of the power electronic device under test includes: obtaining the confidence interval of the radiation power function of the power electronic device under test based on the radiation power function of the power electronic device under test, and determining the upper confidence limit; and if the upper confidence limit is less than the recommended limit, determining that the electromagnetic radiation of the power electronic device under test does not exceed the normal level.

[0013] Optionally, the method further includes: if the upper confidence limit is greater than the recommended limit, determining that the electromagnetic radiation of the power electronic device under test exceeds the normal level.

[0014] To achieve the above object, the present application further provides an evaluation device for the radiation emission level of power electronic devices based on a reverberation chamber, including: a sample acquisition module for acquiring samples of the radiation reception power and transmission coefficient of the reverberation chamber; a model acquisition module for acquiring a radiation power calculation model of the power electronic device to be measured, wherein the power radiation function has a quadratic parameter of the absolute value of the transmission coefficient and a reception power parameter, and the quadratic parameter of the absolute value of the transmission coefficient follows an exponential distribution of a first parameter, and the reception power parameter follows an exponential distribution of a second parameter; a first evaluation module for respectively constructing a first random variable and a second random variable by using the transmission coefficient sample and the reception power sample and their respective maximum sample numbers, constructing a radiation power function of the power electronic device to be measured according to the first random variable, the second random variable, the first parameter and the second parameter, obtaining a probability density function of the radiation power estimated value based on the radiation power function of the power electronic device to be measured, and determining a relative uncertainty model based on the probability density function of the radiation power estimated value, and evaluating the first radiation emission level of the power electronic device to be measured based on the radiation power calculation model and the uncertainty model; a second evaluation module for determining a confidence upper limit of the radiation emission of the power electronic device to be measured according to the radiation power function of the power electronic device to be measured, and evaluating the second radiation emission level of the power electronic device to be measured according to the confidence upper limit.

[0015] To achieve the above object, the present application further provides a computer-readable storage medium, which includes instructions that, when running on a computer, cause the computer to execute the method for evaluating the radiation emission level of power electronic devices based on a reverberation chamber provided in the above embodiment.

[0016] To achieve the above object, the present application further provides an electronic device, which includes: at least one processor, a memory, and an input / output unit; wherein, the memory is used for storing a computer program, and the processor is used for calling the computer program stored in the memory to execute the method for evaluating the radiation emission level of power electronic devices based on a reverberation chamber provided in the above embodiment.

[0017] A method, device, medium, and equipment for evaluating the radiation emission level of power electronic equipment based on a reverberation chamber proposed in an embodiment of the present application include obtaining a reverberation chamber radiation reception power sample and a transmission coefficient sample; obtaining a radiation power calculation model for the power electronic equipment to be measured, where the power radiation function has a quadratic parameter of the absolute value of the transmission coefficient and a reception power parameter, and the quadratic parameter of the absolute value of the transmission coefficient follows an exponential distribution of a first parameter, and the reception power parameter follows an exponential distribution of a second parameter; using the transmission coefficient sample and the reception power sample and their respective sample numbers to construct a first random variable and a second random variable respectively, constructing a radiation power function for the power electronic equipment to be measured according to the first random variable, the second random variable, the first parameter, and the second parameter, obtaining a probability density function of a radiation power estimated value based on the radiation power function of the power electronic equipment to be measured, and determining a relative uncertainty model based on the probability density function of the radiation power estimated value, and evaluating a first radiation emission level of the power electronic equipment to be measured based on the radiation power calculation model and the uncertainty model; determining a confidence upper limit of the radiation emission of the power electronic equipment to be measured according to the radiation power function of the power electronic equipment to be measured, and evaluating a second radiation emission level of the power electronic equipment to be measured according to the confidence upper limit, realizing that the statistical distribution characteristics of the electromagnetic field inside the reverberation chamber can be accurately described, and the influence of independent sampling data on the measurement uncertainty can be quantitatively analyzed, so as to effectively evaluate the statistical characteristics and measurement uncertainty of the radiation emission of power electronic equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 FIG. 6 is a schematic flow chart provided by an embodiment of the method for evaluating the radiation emission level of power electronic equipment based on a reverberation chamber of the present application;

[0019] Figure 2 FIG. 7 is a schematic diagram of a reverberation chamber test environment for radiation emission in an embodiment of the present invention;

[0020] Figure 3 FIG. 8 is the magnitude of the first-order autocorrelation coefficient of a set of turntable and mechanical stirrer samples in an embodiment of the present invention;

[0021] Figure 4 FIG. 9 is the measured total radiation power of two types of switching power supplies used in an embodiment of the present invention;

[0022] Figure 5 FIG. 10 is the relationship between the theoretical and empirical relative uncertainties of the radiation power measurement values of two types of switching power supplies used in an embodiment of the present invention at 3 GHz with the number of independent samples;

[0023] FIG. 11(a) is a comparison result of the radiation emission measurement values of two types of switching power supplies used in an embodiment of the present invention with the recommended limit when the number of independent samples is 10;

[0024] Figure 6(b) shows the comparison results between the measured values of the radiated emissions of two switching power supplies used in the embodiment of the present invention when the number of independent samples is 100 and the recommended limits.

[0025] Figure 7 FIG. 1 is a structural block diagram provided by an embodiment of an apparatus for evaluating the radiated emission level of a power electronic device based on a reverberation chamber according to the present application.

[0026] The realization of the purpose, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. Detailed Embodiment

[0027] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0028] The first object of the present invention is to provide a reverberation chamber test method for radiated emissions. This method can determine the power transfer function in the reverberation chamber and the received power of the receiving antenna when the power electronic device under test is operating based on the reference test and the test of the power electronic device under test, and then achieve accurate measurement of the radiated emissions of the power electronic device under test. In addition, by analyzing the distribution characteristics of the electromagnetic field in the reverberation chamber, this method establishes a theoretical model for the measured value of the total radiated power of the device based on statistical electromagnetic theory, more accurately evaluates the radiated emission level of the device, and thus provides guidance for the electromagnetic compatibility design of power electronic devices.

[0029] The second object of the present invention is to provide a statistical model for measuring radiated emissions by the reverberation chamber method. This model can accurately describe the statistical distribution characteristics of the electromagnetic field inside the reverberation chamber and can quantitatively analyze the influence of independent sampling data on the measurement uncertainty, so as to effectively evaluate the statistical characteristics and measurement uncertainty of the radiated emissions of the device.

[0030] The third object of the present invention is to provide a risk assessment method for the radiated emissions of power electronic devices based on the confidence interval. This method can effectively solve the problem of misjudgment caused by insufficient number of independent samples in the existing test methods, and can intuitively reflect the uncertainty of the radiated emissions of the power electronic device under test according to the size of the confidence interval range, providing a more reliable basis for the electromagnetic compatibility design and risk control of power electronic devices.

[0031] Referring to Figure 1 , the method for evaluating the radiated emission level of a power electronic device based on a reverberation chamber provided by the first embodiment of the present application may include:

[0032] S10. Obtain samples of the received power of the reverberation chamber radiation and samples of the transmission coefficient;

[0033] S20. Obtain the radiation power calculation model of the power electronic device to be tested. Among them, the power radiation function has the quadratic parameter of the absolute value of the transmission coefficient and the received power parameter, and the quadratic parameter of the absolute value of the transmission coefficient follows the exponential distribution of the first parameter, and the received power parameter follows the exponential distribution of the second parameter;

[0034] Specifically, steps S10 - S20 may include the following execution processes:

[0035] Step 1: Connect the reference antenna and the receiving antenna to two ports of the network analyzer respectively, and change the in - field boundary conditions through the mode stirring technique;

[0036] Step 2: At each mode stirring position, the network analyzer collects all transmission coefficient samples;

[0037] Step 3: Use all the collected transmission coefficient samples to estimate the transmission power value G REF , and complete the reference test according to the following formula:

[0038]

[0039] In the formula, η M and η R are the radiation efficiencies of the receiving antenna and the reference antenna respectively, Γ M and Γ R are the reflection coefficients of the receiving antenna and the reference antenna respectively. S 21,REF is the transmission coefficient, N REF is the number of samples in the reference test, and <·> is the sample average operator;

[0040] Step 4: Connect the receiving antenna to the spectrum analyzer and turn on the power electronic device to be tested;

[0041] Step 5: At each mode stirring position, the spectrum analyzer collects the received power samples P M of the power electronic device to be tested;

[0042] Step 6: Use all the collected P M samples to estimate the received power value P REC of the power electronic device to be tested, and complete the test of the power electronic device to be tested according to the following formula;

[0043]

[0044] In the formula, N M is the number of samples in the test of the power electronic device to be tested;

[0045] Step 7: Calculate the total radiation power value of the power electronic device to be tested according to the transmission power value, the received power value and the following formula.

[0046]

[0047] Among them, Equation (3) is the radiation power calculation model of the power electronic device to be measured in this application.

[0048] S30. Use the transmission coefficient samples, received power samples, and their respective maximum sample numbers to construct the first random variable and the second random variable respectively. Construct the radiation power function of the power electronic device to be measured according to the first random variable, the second random variable, the first parameter, and the second parameter. Obtain the probability density function of the radiation power estimate based on the radiation power function of the power electronic device to be measured, and determine the relative uncertainty model based on the probability density function of the radiation power estimate. Evaluate the first radiation emission level of the power electronic device to be measured based on the radiation power calculation model and the uncertainty model.

[0049] It should be noted that in the embodiments of this application, before using the transmission coefficient samples, received power samples, and their respective sample numbers to construct the first random variable and the second random variable respectively, the method for evaluating the radiation emission level of power electronic devices based on a reverberation chamber proposed in this application may further include the following execution process:

[0050] Judge the independence of the transmission coefficient samples and the received power samples according to the magnitudes of the first-order autocorrelation coefficients of the transmission coefficient samples / received power samples respectively.

[0051] Specifically, in the embodiments of this application, the step of judging the independence of the transmission coefficient samples and the received power samples according to the magnitudes of the first-order autocorrelation coefficients of the transmission coefficient samples / received power samples respectively may include the following execution process:

[0052] Obtain the transmission coefficient samples / radiation received power samples of the turntable or the stirrer respectively;

[0053] Calculate the first-order autocorrelation coefficient of the transmission coefficient samples / radiation received power samples generated by the turntable or the stirrer;

[0054] Judge whether the samples are independent according to the magnitude relationship between the first-order autocorrelation coefficient and a preset threshold. Among them, if the autocorrelation coefficient is less than the preset threshold, the samples are independent; otherwise, the samples are not independent.

[0055] Exemplarily, the above steps may include:

[0056] Calculate the first-order autocorrelation coefficient of the turntable or mechanical stirrer samples

[0057]

[0058] In the formula, S 21(i) is the i-th turntable or agitator sample, S 21 (i + 1) is S 21 The sample that moves one position of (i);

[0059] Compare the magnitude of the first-order autocorrelation coefficient of the sample with the threshold value to verify that the samples collected at different mode agitation positions are independent of each other;

[0060] In view of the fact that the statistical model of the power electronic device to be tested is a function of the number of independent samples, it is necessary to test the independence between samples before analyzing the statistical characteristics of the power supply radiation emission.

[0061] S40. Determine the confidence upper limit of the radiation emission of the power electronic device to be tested according to the radiation power function of the power electronic device to be tested, and evaluate the second radiation emission level of the power electronic device to be tested according to the confidence upper limit.

[0062] This application provides a method for evaluating the radiation emission level of a power electronic device based on a reverberation chamber. Through a method, device, medium and equipment for evaluating the radiation emission level of a power electronic device based on a reverberation chamber, by obtaining the radiation reception power sample and the transmission coefficient sample of the reverberation chamber; obtaining the radiation power calculation model of the power electronic device to be tested, wherein the power radiation function has a quadratic parameter of the absolute value of the transmission coefficient and a reception power parameter, and the quadratic parameter of the absolute value of the transmission coefficient follows an exponential distribution of a first parameter, and the reception power parameter follows an exponential distribution of a second parameter; using the transmission coefficient sample and the reception power sample and their respective maximum sample numbers to construct a first random variable and a second random variable respectively, constructing the radiation power function of the power electronic device to be tested according to the first random variable, the second random variable, the first parameter and the second parameter, obtaining the probability density function of the radiation power estimated value based on the radiation power function of the power electronic device to be tested, and determining the relative uncertainty model based on the probability density function of the radiation power estimated value, and evaluating the first radiation emission level of the power electronic device to be tested based on the radiation power calculation model and the uncertainty model; determining the confidence upper limit of the radiation emission of the power electronic device to be tested according to the radiation power function of the power electronic device to be tested, and evaluating the second radiation emission level of the power electronic device to be tested according to the confidence upper limit. It realizes that the statistical distribution characteristics of the electromagnetic field inside the reverberation chamber can be accurately described, and the influence of the independent sampling number on the measurement uncertainty can be quantitatively analyzed, so as to effectively evaluate the statistical characteristics and measurement uncertainty of the radiation emission of the power electronic device.

[0063] In the embodiment of this application, step S30 may include the following execution process:

[0064] S301. Obtain a first random variable based on the product of the sum of the squares of the transmission coefficient samples and the number of samples of the transmission coefficient samples;

[0065] S302. Determine a second random variable based on the product of the sum of received power samples and the number of the received power samples;

[0066] S303. Obtain a first chi-square distribution based on the product of the first random variable and a first parameter;

[0067] S304. Obtain a second chi-square distribution based on the product of the second random variable and a second parameter;

[0068] S305. Rewrite the radiation power calculation model based on the first chi-square distribution and the second chi-square distribution to obtain the radiation power function of the power electronic device under test.

[0069] Specifically, the above steps may include the following execution processes:

[0070] According to Hill's plane wave integration theory, the variable X = |S 21,REF | 2 and the variable Y = P M follow an exponential distribution, denoted as X ~ E(λ REF ) and Y ~ E(λ M );

[0071] Define the first random variable R = ∑N REF X i , the second random variable G = ∑N M Y i , λ REF R and λ M G follow a chi-square distribution with degrees of freedom 2N REF and 2N M respectively, denoted as the first chi-square distribution λ REF R ~ χ 2 (2N REF ) and the second chi-square distribution λ M G ~ χ 2 (2N M ). Rewrite the radiation power calculation model P RE of the power electronic device under test into a form containing variables R and G

[0072]

[0073] Define the random variable Z = P RE , a = λ M / [λ REF η R (1 - |Γ R | 2 )], aZ should follow a central F distribution with degrees of freedom 2N M and 2N REF respectively, denoted as aZ ~ F(2NM , 2N REF ), derive P RE The probability density function of

[0074]

[0075] Based on the radiation power function of the power electronic device under test, obtaining the probability density function of the radiation power estimate value, and determining the relative uncertainty model based on the probability density function of the radiation power estimate value may include the following execution processes:

[0076] Determine the expectation of the radiation power and the variance of the radiation power according to the probability density function of the radiation power estimate value;

[0077] Determine the relative uncertainty model based on the expectation of the radiation power and the variance of the radiation power.

[0078] Exemplarily, the above steps may include:

[0079] Calculate the expectation and variance according to the probability density function

[0080]

[0081] Obtain the relative uncertainty model according to the expectation and variance

[0082]

[0083] In the embodiments of the present application, step S40 may include the following execution processes:

[0084] S401. Based on the radiation power function of the power electronic device under test, obtain the upper confidence limit of the radiation power function of the power electronic device under test;

[0085] S402. If the upper confidence limit is less than the recommended limit, it is determined that the electromagnetic radiation of the power electronic device under test does not exceed the normal level.

[0086] Exemplarily, the above steps may include the following steps:

[0087] According to the reverberation chamber test part of the electromagnetic compatibility standard GB / T 9254.1, the conversion relationship between the radiation power measurement value P RE and the free space electric field strength at an equivalent distance of 3m

[0088] E rad = P RE + 97.53 dB(11)

[0089] Obtain the free space electric field strength E rad ;

[0090] Using a statistical model, calculate the confidence interval of the radiated emissions of the power electronic equipment to be tested;

[0091] Search for the electromagnetic compatibility standard GB / T 9254.1 to obtain the recommended limit value of radiated emissions in this frequency range;

[0092] Compare the upper limit of the 95% confidence interval of the calculated radiated power or electric field strength with the standard limit value. If the upper limit of the confidence interval is lower than the standard limit value, it is considered that the radiated emissions of the power electronic equipment to be tested meet the standard requirements; otherwise, there is a risk of exceeding the standard.

[0093] If there is a risk of exceeding the standard, quantify the risk level according to the range of the confidence interval of the exceeded part. The larger the range of the confidence interval of the exceeded part, the higher the risk of exceeding the standard; conversely, the lower the risk of exceeding the standard.

[0094] Specifically, the steps of using the statistical model to calculate the confidence interval of the radiated emissions of the power electronic equipment to be tested may include:

[0095] Determine the confidence level 1-α according to the requirements;

[0096] Calculate the radiated power P RE The upper limit a of the confidence interval at the confidence level of 1-α -1 F 1-0.5α (2N M , 2N REF ) and the lower limit a - 1 F 0.5α (2N M , 2N REF );

[0097] According to the F-distribution critical value table, query the upper and lower limits of the confidence interval to determine the confidence interval range.

[0098] Compared with the prior art, the present invention has at least the following beneficial effects:

[0099] 1. The present invention provides a reverberation chamber test model for radiated emissions based on statistical electromagnetic theory, which can accurately describe the statistical distribution characteristics of the electromagnetic field inside the reverberation chamber and can quantitatively analyze the influence of the independent sampling number on the measurement uncertainty, so as to effectively evaluate the statistical characteristics and measurement uncertainty of the radiated emissions of power electronic equipment.

[0100] 2. The present invention provides a risk assessment method for radiated emissions based on the confidence interval, which can judge whether the radiated emissions of the equipment meet the standard requirements according to the calculated confidence interval of the radiated emissions, effectively reduce the misjudgment caused by insufficient independent sample numbers, and provide a more scientific decision-making basis for the electromagnetic compatibility design and risk control of power electronic equipment.

[0101] 3. The present invention applies the statistical electromagnetic theory to the reverberation chamber test of the radiation emission of power electronic devices, realizes the quantitative evaluation of the statistical characteristics and measurement uncertainty of the test results, provides a theoretical basis for the analysis of the reverberation chamber test results, and helps to promote the application and popularization of the statistical electromagnetic theory in other reverberation chamber tests.

[0102] The following further describes the present invention in detail with reference to the drawings and embodiments.

[0103] The schematic diagram of the reverberation chamber used in the embodiment of the present invention is as Figure 2 shown. The size of the reverberation chamber is 1.50 m × 1.44 m × 0.92 m, and there are two mechanical stirrers and a turntable inside. An antenna support with adjustable height is equipped on the turntable. The reference antenna is a discone antenna, and the receiving antenna is a standard horn antenna. The receiving antenna is installed on the support at the bottom surface of the reverberation chamber, and the reference antenna is installed on the support of the turntable and is 20 cm away from the center of the turntable (the diameter of the turntable is 60 cm). The power electronic device to be tested is connected to the load and placed on another support of the turntable, also 20 cm away from the center of the turntable. During the reference test, the reference antenna and the receiving antenna are respectively connected to the two ports of the network analyzer. When testing the power electronic device to be tested, the receiving antenna is connected to the port of the spectrum analyzer. The power electronic device to be tested selects a common switch power supply on the market; the load is a pure resistive heating resistor with a resistance value of 25.

[0104] The test frequency band of the embodiment of the present invention is from 1 GHz to 4 GHz. The stirrer and the turntable rotate independently, and there are 10 different stopping positions in one rotation, so there are 100 stirring positions in one test. During the whole test process, the spatial position of the receiving antenna remains unchanged. In view of the fact that calculating the relative uncertainty of the radiation emission requires multiple independent radiation emission measurement samples, the 9-point test method is adopted in this paper to repeat the above experiment multiple times. The 9-point test method refers to adjusting the supports for the power electronic device to be tested and the reference antenna, so that the power electronic device to be tested and the reference antenna are distributed at three different vertical heights, and the distance between each height is greater than half of the wavelength of the lowest test frequency. And at each height, the power electronic device to be tested and the reference antenna are respectively oriented in three mutually perpendicular directions.

[0105] For the radiation emission of two types of switch power supplies in the embodiment of the present invention, the calculation results of the amplitude of the first-order autocorrelation coefficient of power supply A and power supply B are as Figure 3As shown, the threshold value is taken as... It can be found that, throughout the entire frequency band, it is basically lower than the threshold value. Therefore, it can be considered that the 100 samples obtained within the range of 1 GHz - 2 GHz are independent of each other. The power supply A is of Mean Well brand, with an input of 220V ~ 50Hz alternating current, an output of 24V direct current, and a rated power of 76.8W; the power supply B is of Hetian Shengming brand, with an input of 220V ~ 50Hz alternating current, an output of 12V direct current, and a rated power of 50.4W.

[0106] The radiation emission test results of the two switching power supplies in the embodiments of the present invention are as Figure 4 shown. Since the output voltage of power supply A is twice that of power supply B, under the same load, the output power of power supply A is four times that of power supply B. The results show that the radiation power of power supply A is significantly higher than that of power supply B, indicating that equipment with a larger output power usually generates stronger electromagnetic radiation during operation.

[0107] The relationship between the theoretical and empirical relative uncertainties of the measured radiation power values of the two switching power supplies used in the embodiments of the present invention at 3 GHz as a function of the number of independent samples is as Figure 5 shown. It can be seen that regardless of the number of independent samples and the output power of the power electronic equipment under test, the theoretically calculated values of the relative uncertainty are in good agreement with the empirically measured values. This phenomenon strongly corroborates the accuracy and reliability of the theoretical uncertainty model.

[0108] In the embodiments of the present invention, when the number of independent samples is 10 and 100 respectively, the radiation emission measurement values of the two switching power supplies are compared, and the corresponding 95% confidence intervals are shown. The results are as shown in Figure 6. When the number of independent samples is 10, the 95% confidence interval is relatively wide, indicating a large measurement uncertainty; when the number of independent samples increases to 100, the confidence interval significantly narrows, indicating that the measured values are more stable and reliable. Thus, a smaller number of independent samples is likely to cause the measured values to deviate from the true values. Therefore, when evaluating the radiation emission of power electronic equipment, the influence of the number of independent samples must be considered. The present invention innovatively uses the upper limit of the 95% confidence interval to compare with the reference limit, which can more reliably judge the radiation emission, thereby reducing the risk of misjudgment caused by insufficient independent samples.

[0109] Reference Figure 7 , based on the above embodiments, the present application further provides a device for evaluating the radiation emission level of power electronic equipment based on a reverberation chamber. The device 1000 for evaluating the radiation emission level of power electronic equipment includes:

[0110] The model acquisition module 1001 is used to acquire the radiation power calculation model of the power electronic device to be measured. Among them, the power radiation function has the quadratic parameter of the absolute value of the transmission coefficient and the received power parameter, and the quadratic parameter of the absolute value of the transmission coefficient follows the exponential distribution of the first parameter, and the received power parameter follows the exponential distribution of the second parameter;

[0111] The first evaluation module 1002 is used to respectively construct the first random variable and the second random variable by using the transmission coefficient sample and the received power sample and their respective maximum sample numbers, construct the radiation power function of the power electronic device to be measured according to the first random variable, the second random variable, the first parameter and the second parameter, obtain the probability density function of the radiation power estimated value based on the radiation power function of the power electronic device to be measured, and determine the relative uncertainty model based on the probability density function of the radiation power estimated value, and evaluate the first radiation emission level of the power electronic device to be measured based on the radiation power calculation model and the uncertainty model;

[0112] The second evaluation module 1003 is used to determine the upper confidence limit of the radiation emission of the power electronic device to be measured according to the radiation power function of the power electronic device to be measured, and evaluate the second radiation emission level of the power electronic device to be measured according to the upper confidence limit.

[0113] Based on the above embodiments, the present application also provides a computer-readable storage medium, which includes instructions that, when running on a computer, cause the computer to execute the method for evaluating the radiation emission level of a power electronic device based on a reverberation chamber provided in any one of the above embodiments.

[0114] Based on the above embodiments, the present application also provides an electronic device, which includes: at least one processor, a memory, and an input / output unit; wherein, the memory is used to store a computer program, and the processor is used to call the computer program stored in the memory to execute the method for evaluating the radiation emission level of a power electronic device based on a reverberation chamber provided in any one of the above embodiments.

[0115] The above are only the preferred embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, are equally included in the patent protection scope of the present application.

Claims

1. A method for evaluating the radiated emission level of power electronic equipment based on a reverberation chamber, characterized in that: include: Obtaining the radiated received power samples and transmission coefficient samples of the reverberation chamber; Acquire a radiation power calculation model of the power electronic device to be tested, wherein the power radiation function has a quadratic parameter of the absolute value of the transmission coefficient and a received power parameter, and the quadratic parameter of the absolute value of the transmission coefficient obeys an exponential distribution of a first parameter, and the received power parameter obeys an exponential distribution of a second parameter; Using the transmission coefficient samples and the received power samples and their respective sample numbers, respectively constructing a first random variable and a second random variable, constructing a radiation power function of the power electronic device to be tested according to the first random variable and the second random variable and the first parameter and the second parameter, obtaining a probability density function of a radiation power estimation value based on the radiation power function of the power electronic device to be tested, determining a relative uncertainty model based on the probability density function of the radiation power estimation value, and evaluating a first radiation emission level of the power electronic device to be tested based on the radiation power calculation model and the uncertainty model; An upper confidence limit of the radiation emission of the power electronic device to be tested is determined according to the radiation power function of the power electronic device to be tested, and a second radiation emission level of the power electronic device to be tested is evaluated according to the upper confidence limit.

2. The method for evaluating the radiation emission level of power electronic equipment based on a reverberation chamber according to claim 1, characterized in that: Before constructing the first random variable and the second random variable respectively by using the transmission coefficient samples and the received power samples and the number of samples thereof, the method further includes: The independence of the transmission coefficient sample and the reception power sample is determined according to the amplitude of the first-order autocorrelation coefficient of each transmission coefficient sample / reception power sample.

3. The method for evaluating the radiation emission level of power electronic equipment based on a reverberation chamber as claimed in claim 2, characterized in that: The step of judging the independence of the transmission coefficient sample and the reception power sample according to the amplitude of the first-order autocorrelation coefficient of each of the transmission coefficient sample and the reception power sample comprises: Obtaining transmission coefficient samples / radiation received power samples of the turntable or stirrer; Calculate the first-order autocorrelation coefficient of the transmission coefficient sample / radiation received power sample generated by the turntable or stirrer; Whether the samples are independent is determined based on the magnitude relationship between the first-order autocorrelation coefficient and a preset threshold, wherein if the autocorrelation coefficient is less than the preset threshold, the samples are independent, otherwise, the samples are not independent.

4. The method for evaluating the radiation emission level of power electronic equipment based on a reverberation chamber according to claim 1, characterized in that: The method uses the transmission coefficient samples and the received power samples and their respective sample numbers to construct the first random variable and the second random variable respectively, and constructs the radiation power function of the power electronic device to be tested according to the first random variable and the second random variable and the first parameter and the second parameter, including: Obtaining a first random variable based on a product of a sum of squares of transmission coefficient samples and the number of samples of the transmission coefficient samples; Obtaining a second random variable based on the sum of the received power samples and the product of the number of samples of the received power samples; A first chi-square distribution is obtained based on the product of the first random variable and the first parameter; A second chi-square distribution is obtained based on the product of the second random variable and the second parameter; A radiation power calculation model is rewritten based on the first chi-square distribution and the second chi-square distribution to obtain a radiation power function of the power electronic device to be tested.

5. The method for evaluating the radiation emission level of power electronic equipment based on a reverberation chamber according to claim 1, characterized in that: The determining of the relative uncertainty model based on the probability density function of the radiation power estimation value comprises: Determine the expected value of the radiated power and the variance of the radiated power according to the probability density function of the radiated power estimate; A relative uncertainty model is determined based on the expectation of the radiated power and the variance of the radiated power.

6. The method for evaluating the radiation emission level of power electronic equipment based on a reverberation chamber according to claim 4, characterized in that: Determining the confidence upper limit of the radiation emission of the power electronic device to be tested according to the radiation power function of the power electronic device to be tested includes: Based on the radiation power function of the power electronic device to be tested, obtaining a confidence interval of the radiation power function of the power electronic device to be tested; If the upper confidence limit is less than the recommended limit, it is judged that the electromagnetic radiation of the power electronic equipment under test does not exceed the normal level.

7. The method for evaluating the radiation emission level of power electronic equipment based on a reverberation chamber according to claim 1, characterized in that: The method further comprises: If the upper confidence limit is greater than the recommended limit, it is judged that the electromagnetic radiation of the power electronic equipment under test exceeds the normal level.

8. A device for evaluating the radiation emission level of power electronic equipment based on a reverberation chamber, characterized in that: include: A sample acquisition module is used to acquire the radiation receiving power sample and the transmission coefficient sample of the reverberation chamber; A model acquisition module, used to acquire a radiation power calculation model of the power electronic device to be tested, wherein the power radiation function has a quadratic parameter of the absolute value of the transmission coefficient and a received power parameter, and the quadratic parameter of the absolute value of the transmission coefficient obeys an exponential distribution of a first parameter, and the received power parameter obeys an exponential distribution of a second parameter; A first evaluation module is used to construct a first random variable and a second random variable respectively by using the transmission coefficient sample and the received power sample and the number of samples thereof, construct a radiation power function of the power electronic device to be tested according to the first random variable and the second random variable and the first parameter and the second parameter, obtain a probability density function of a radiation power estimation value based on the radiation power function of the power electronic device to be tested, determine a relative uncertainty model based on the probability density function of the radiation power estimation value, and evaluate a first radiation emission level of the power electronic device to be tested based on the radiation power calculation model and the uncertainty model; The second evaluation module is used to determine the upper confidence limit of the radiation emission of the power electronic device to be tested according to the radiation power function of the power electronic device to be tested, and evaluate the second radiation emission level of the power electronic device to be tested according to the upper confidence limit.

9. A computer-readable storage medium, characterized in that: The method comprises instructions, which, when executed on a computer, enable the computer to execute the method for evaluating the radiation emission level of power electronic equipment based on a reverberation chamber as claimed in any one of claims 1 to 7.

10. An electronic device, characterized in that: The electronic device comprises: at least one processor, memory, and input-output unit; The memory is used to store a computer program, and the processor is used to call the computer program stored in the memory to execute the method for evaluating the radiation emission level of power electronic equipment based on a reverberation chamber according to any one of claims 1 to 7.

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