Radiated electromagnetic interference prediction method distinguishing between vertical and horizontal polarization components

Abstract

The application relates to a radiation electromagnetic interference prediction method for distinguishing vertical polarization and horizontal polarization components, first, according to the actual structure of a converter and an external connecting cable, a vertical polarization reference direction and a horizontal polarization reference plane are determined, the cable is divided into a plurality of radiation units, and vertical polarization radiation function and horizontal polarization radiation function vectors are established; then, vertical polarization radiation electromagnetic interference field strength models and horizontal polarization radiation electromagnetic interference field strength models are constructed, and dual-polarization radiation field strength prediction is realized; finally, a dual-polarization radiation electromagnetic interference prediction result sequence is established, dual-polarization field strength difference is calculated, the dominant polarization direction under each frequency is judged, and the polarization conversion frequency between the vertical polarization and the horizontal polarization is determined; the application can realize independent radiation electromagnetic interference spectrum prediction, dual-polarization radiation characteristic prediction under a specified frequency and dominant polarization change rule prediction in a target prediction frequency range, and can effectively represent the polarization characteristics in the radiation electromagnetic interference of the power electronic converter.

Description

Technical Field

[0001] This invention belongs to the field of power electronic electromagnetic interference prediction technology, specifically involving a method for predicting radiated electromagnetic interference that distinguishes between vertical and horizontal polarization components. Background Technology

[0002] As power electronic converters develop towards higher frequencies, higher power densities, and higher integration, the high-frequency voltage and current changes generated during the high-speed switching of power devices are continuously increasing. This leads to more pronounced high-frequency common-mode excitation in the internal conductor structure, power circuit, and external connecting cables of the converter. When this high-frequency common-mode current propagates along the internal conductive structure and external connecting cables, it generates corresponding radiated electromagnetic interference, which propagates to the surrounding environment in the form of spatial electromagnetic fields.

[0003] Radiated electromagnetic interference exhibits distinct electromagnetic polarization characteristics during its propagation through space. Its radiation field can typically be decomposed into mutually orthogonal vertical and horizontal polarization components. For power electronic converters, due to the strong non-uniformity of internal conductor structure, external cable arrangement, and high-frequency common-mode current distribution, the contributions of vertical and horizontal polarization radiation generated under different structures and frequencies differ significantly. Therefore, predicting radiation solely using the total amplitude of the radiation field is insufficient to reveal the sources and variation patterns of radiation corresponding to different polarization directions.

[0004] However, existing methods for predicting radiated electromagnetic interference typically establish the relationship between the excitation source, current distribution, and radiated field strength directly, focusing on the overall amplitude of the radiated field strength without independently modeling and analyzing the different polarization components in the radiated field. When the converter structure or the direction of the connecting cables changes, the radiated contribution corresponding to different polarization directions may change, making it difficult for traditional methods to further determine the main radiated polarization directions within a certain frequency range and the variation of polarization characteristics with frequency.

[0005] Therefore, it is necessary to establish a method that can independently describe and predict the vertical and horizontal polarization components in the radiated electromagnetic interference of power electronic converters, realize the analysis of dual-polarization radiation results, and provide a basis for the structural optimization and electromagnetic compatibility design of power electronic equipment. Summary of the Invention

[0006] This invention provides the following technical solution: a method for predicting radiated electromagnetic interference that distinguishes between vertical and horizontal polarization components, comprising the following steps: Step 1: Construct a dual-polarization effective radiation length model: Taking the power electronic converter and its external connecting cables as the objects of radiated electromagnetic interference prediction, determine the vertical polarization reference direction and the horizontal polarization reference plane based on the actual installation status of the equipment and the actual ground direction. Define the unit vector perpendicular to the actual ground upward as the vertical polarization unit vector. Divide the external connection cables into The segment of the radiation unit, according to the first directional length vector of cable segment Determine the vertically polarized effective radiation length vector corresponding to each segment of the cable. and horizontally polarized effective radiation length vector To characterize the geometric effect of cable structure on vertical and horizontal polarization radiation; Step 2: Construct a common-mode current model for external connection cables: based on the common-mode noise voltage at the power electronic converter port. Propagation path impedance between common-mode noise source and external connection cable port and the port impedance presented by external connection cables at the power electronic converter ports. Determine the common-mode excitation current flowing into the external connection cable. Further combining the common-mode current propagation constant Common-mode current reflection coefficient of cable terminals Total cable path length and the external connection cable starting point to the first Path length at the center of the cable segment Determine the first Common-mode current at the center of the cable segment ; Step 3: Construct the vertical and horizontal polarization radiation function models: based on the common-mode current corresponding to each radiation element. Determine the normalized common-mode current coefficient According to the first Center position of cable segment With predicted location The spatial relationship between them determines the propagation distance. Propagation direction unit vector and prediction frequency Corresponding wave number Combined with the effective radiation length vector of vertical polarization Horizontal polarization effective radiation length vector The propagation phase is then used to coherently superimpose the radiation contributions of each segment, yielding the predicted locations. Vertical polarization radiation function at and horizontal polarization radiation function vector ; Step 4: Construct electromagnetic interference field strength models for vertical and horizontal polarization radiation: Based on the vertical polarization radiation function and horizontal polarization radiation function vector Determine the vertically polarized normalized radiation intensity respectively and horizontal polarization normalized radiation intensity The vertical polarization directional gain was obtained based on the same total radiation normalization criterion. and horizontal polarization directional gain ; Further increase the common-mode excitation current Propagation medium wave impedance External connection cable radiation efficiency Port radiation resistance Correlate the corresponding polarization directional gain to obtain the predicted position. Vertical polarization radiated electromagnetic interference field strength at the location and horizontal polarized radiated electromagnetic interference field strength ; Step 5: Construct a dual-polarization spectrum and dominant polarization determination model: Set within the target prediction frequency band Frequency sampling points Based on the vertical polarization radiated electromagnetic interference field strength corresponding to each frequency sampling point and horizontal polarized radiated electromagnetic interference field strength Each of these forms a predicted spectrum of vertically polarized radiated electromagnetic interference. Predicted spectrum of horizontally polarized radiated electromagnetic interference Further calculations were performed on the difference in dual-polarization field strength at each frequency sampling point. and according to The positive and negative relationship determines the dominant polarization at the corresponding frequency sampling point. ; Step 6: Construct a sequence of prediction results for dual-polarized radiated electromagnetic interference: This involves sampling points at each frequency within the target prediction frequency band. Corresponding vertically polarized radiated electromagnetic interference field strength Horizontal polarized radiated electromagnetic interference field strength Difference in polarization field strength and dominant polarization The prediction results of dual-polarized radiated electromagnetic interference are uniformly correlated and sequentially organized according to the frequency sampling order to form a sequence. Based on the difference in dual-polarization field strength corresponding to adjacent frequency sampling points Changes in the polarization transition frequency that indicate a shift in the dominance of vertical and horizontal polarization. And form a set of polarization conversion frequencies. .

[0007] Based on the predicted sequence of dual-polarization radiated electromagnetic interference results and polarization conversion frequency set It enables independent prediction of electromagnetic interference spectra of vertical and horizontal polarization radiation, prediction of dual-polarization radiation characteristics at a specified frequency, and prediction of the dominant polarization change law within the target prediction frequency band.

[0008] Preferably, in step 1, the first Vertical polarization effective radiation length vector corresponding to the cable segment for: (1) Horizontal polarization effective radiation length vector for: (2) In the formula, Represents the vertically polarized unit vector pointing upwards from the real ground; Indicates the first The directional length vector of the external connecting cable segment; and They represent the first The effective radiation length vector of the vertical polarization and the effective radiation length vector of the horizontal polarization of the cable segment.

[0009] Preferably, in step 2, the common-mode excitation current for: (3) No. Common-mode current at the center of the cable segment for: (4) In the formula, Indicates the predicted frequency; This represents the common-mode noise voltage at the port of the power electronic converter; This represents the propagation path impedance between the common-mode noise source and the external connection cable port. This indicates the port impedance presented by the external connection cable at the power electronic converter port; Indicates the connection cable from the start end to the... The path length at the center of the cable segment; Indicates the total path length of the external connection cable; Represents the common-mode current propagation constant; This represents the common-mode current reflection coefficient of the cable termination.

[0010] Preferably, in step 3, the first Normalized common-mode current coefficient corresponding to the cable segment for: (7) No. Center position of cable segment To the predicted position propagation distance for: (9) Propagation direction unit vector for: (10) Prediction frequency Corresponding wave number for: (11) Vertical polarization radiation function for: (12) Horizontal polarization radiation function vector for: (14) In the formula, Indicates the total number of segments in the external connection cable; and These are the magnetic permeability and dielectric constant of the propagation medium, respectively. It represents the imaginary unit.

[0011] Preferably, in step 4, the vertically polarized normalized radiation intensity and horizontal polarization normalized radiation intensity They are respectively: (16) (18) Vertical polarization directional gain for: (20) Horizontal polarization directional gain for: (twenty two) Vertical polarized radiated electromagnetic interference field strength for: (twenty four) Horizontal polarized radiated electromagnetic interference field strength for: (27) In the formula, Ω represents the closed far-field directional domain surrounding the power electronic converter and its external connecting cables; dΩ′ represents the solid angle element. Indicates the wave impedance of the propagation medium; Indicates the frequency of the external connection cable. Radiation efficiency at the lower level; This indicates the radiation resistance of the external connection cable port.

[0012] Preferably, in step 5, frequency sampling points are set in the target predicted frequency band. , and according to and Construct the predicted spectrum of vertically polarized radiated electromagnetic interference respectively Predicted spectrum of horizontally polarized radiated electromagnetic interference .

[0013] Dual-polarization field intensity difference at each frequency sampling point for: (32) Based on the difference in bipolar field strength The positive and negative relationship determines the dominant polarization at the corresponding frequency sampling point. : (33) In the formula, v represents that vertical polarization radiation is dominant, h represents that horizontal polarization radiation is dominant, and e represents that the field strengths of vertical and horizontal polarization radiation are equal.

[0014] Preferably, in step 6, the frequencies of each frequency sampling point within the target prediction frequency band are... Vertical polarization radiated electromagnetic interference field strength Horizontal polarized radiated electromagnetic interference field strength Difference in polarization field strength and dominant polarization The prediction results of dual-polarized radiated electromagnetic interference are generated by correlating the results according to the frequency sampling order. : (36) Further, all polarization conversion frequencies identified within the target prediction frequency band will be... By combining them, a set of polarization switching frequencies is formed. : (37) In the formula, Indicates the predicted location The sequence of predicted results for dual-polarized radiated electromagnetic interference at the location; Indicates the first frequency band within the target prediction band The frequency at which the dominant relationship between vertical and horizontal polarization shifts; Indicates the total number of polarization conversion frequencies; Indicates the predicted location The set of polarization conversion frequencies within the target prediction frequency band.

[0015] More preferably, based on the output of step 6, the radiated electromagnetic interference prediction method achieves at least one of the following functions: a. Output independent prediction results of the electromagnetic interference spectrum of vertically polarized and horizontally polarized radiation.

[0016] b. Output the predicted results of dual-polarization radiation characteristics at the specified frequency.

[0017] c. Output the prediction results of the dominant polarization change law within the target prediction frequency band.

[0018] The beneficial effects of this invention are: 1. This invention achieves decoupled prediction of dual-polarization components of radiated electromagnetic interference (EMI) in power electronic converters. By constructing a prediction result sequence of dual-polarization EMI, independent prediction and analysis of the radiation spectra of vertical and horizontal polarization can be completed separately. This overcomes the limitations of traditional overall amplitude analysis methods, which suffer from single-dimensionality and lack of information. It can comprehensively and precisely characterize the spectral distribution features of radiated interference in different polarization directions and accurately distinguish the differences in radiation contribution of the two types of polarization components across the entire frequency band.

[0019] 2. This invention supports multi-scenario and multi-dimensional polarization characteristic analysis. It can quantitatively predict the radiation characteristics of vertical and horizontal polarization at a specified single frequency, accurately obtain the polarization radiation intensity and distribution characteristics at a specific frequency point, and dynamically identify the dominant polarization type within the target prediction frequency band. It can effectively capture the switching rules of the dominant radiation polarization direction and the evolution trend of polarization characteristics in different frequency intervals, solving the industry pain point that traditional methods cannot determine the dominant polarization of a frequency band and cannot characterize the polarization variation with frequency.

[0020] 3. This invention provides reliable data support and theoretical basis for the refined electromagnetic compatibility (EMC) design and structural optimization of power electronic converters. Based on the independent prediction results of dual-polarization components, engineers can accurately locate the sources of polarization radiation interference corresponding to different structures and cable layouts, and carry out targeted EMC improvements such as converter body structure optimization, external cable layout rectification, and high-frequency circuit layout optimization. This effectively improves the EMC suppression effect of power electronic equipment, reduces the risk of equipment radiation exceeding standards, and ensures the stable and reliable operation of power electronic systems under high-frequency, high-integration, and high-density operating conditions, demonstrating good engineering practicality and promising prospects for widespread application. Attached Figure Description

[0021] Figure 1 This is a flowchart of the radiated electromagnetic interference prediction method that distinguishes between vertical and horizontal polarization components according to the present invention. Detailed Implementation

[0022] The relevant technologies of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0023] like Figure 1 As shown, the radiated electromagnetic interference prediction method of this embodiment includes the following steps: Step 1: Taking the power electronic converter and its external connecting cables as the objects of radiated electromagnetic interference prediction, determine the vertical polarization reference direction and the horizontal polarization reference plane based on the actual installation status of the power electronic converter and the actual ground orientation. Define the unit vector perpendicular to the actual ground upwards as the vertical polarization unit vector. .

[0024] Based on the directional length vector of the nth segment of the external connection cable Calculate the effective radiation length vector of this cable segment in the vertical polarization direction and in the horizontal polarization reference plane, respectively: (1) (2) in, Let be the effective vertical polarization radiation length vector of the nth cable segment. Let be the effective radiation length vector of the horizontal polarization of the nth cable segment.

[0025] Corresponding to each segment of external connection cable and These parameters characterize the geometric effects of the cable structure on vertical and horizontal polarization radiation, and are used as geometric parameters for subsequent calculations of the vertical and horizontal polarization radiation function vectors.

[0026] Step 2: Determine the common-mode excitation current flowing into the external connection cable. and the common-mode current at the center of each cable segment : (3) in, To predict frequency, This refers to the common-mode noise voltage at the port of the power electronic converter. The propagation path impedance between the common-mode noise source and the external connection cable port. This refers to the port impedance presented by the external connection cable at the power electronic converter port. This refers to the common-mode excitation current flowing into the external connection cable.

[0027] Further considering the amplitude attenuation, phase delay, and terminal reflection of the common-mode current as it propagates along the external connecting cable, the common-mode current at the center of the nth cable segment is obtained as follows: (4) in, Let be the common-mode current at the center of the nth cable segment. Let L be the path length from the starting point of the external connection cable to the center of the nth cable segment, and L be the total path length of the external connection cable. Let be the common-mode current propagation constant. This is the common-mode current reflection coefficient of the cable terminal.

[0028] The common-mode current propagation constant is: (5) in, Let be the attenuation constant for common-mode current propagation. Let be the phase constant for common-mode current propagation, and j be the imaginary unit.

[0029] The common-mode current reflection coefficient of the cable terminal is: (6) in, This refers to the common-mode load impedance at the termination of the external connection cable. This is the common-mode characteristic impedance of the external connection cable.

[0030] This allows us to obtain the common-mode current for each segment of the external connection cable. This is used for subsequent combination with the vertically polarized effective radiation length vector. and horizontally polarized effective radiation length vector Calculate the vertical polarization radiation function and the horizontal polarization radiation function vector, respectively.

[0031] Step 3: Determine the normalized common-mode current coefficient for each cable segment. The propagation distance from the center of each cable segment to the predicted location. Propagation direction unit vector and the wavenumber corresponding to the predicted frequency : (7) in, is the normalized common-mode current coefficient of the nth cable segment, used to characterize the amplitude and phase relationship of the common-mode current of this cable segment relative to the common-mode excitation current at the cable's starting end.

[0032] Determine the predicted location of radiated electromagnetic interference And the center position of the nth cable segment is denoted as The propagation distance vector from the center position of the nth cable segment to the predicted position is obtained: (8) Furthermore, the corresponding propagation distance is obtained: (9) Therefore, the first The propagation direction unit vector from the center position of the cable segment to the predicted position: (10) in, For the propagation distance vector, For transmission distance, The propagation direction is the unit vector. , and These are unit vectors in the x-axis, y-axis, and z-axis directions, respectively.

[0033] Determine the corresponding wavenumber based on the predicted frequency and propagation medium parameters: (11) in, For frequency The corresponding wave number, and These are the magnetic permeability and dielectric constant of the propagation medium, respectively.

[0034] Step 4, Determine the predicted location Vertical polarization radiation function at and horizontal polarization radiation function vector .

[0035] Based on the normalized common-mode current coefficient, effective vertical polarization radiation length vector, propagation direction unit vector, propagation distance, and propagation phase of each external connection cable segment, the vertical polarization radiation contribution generated by each cable segment is coherently superimposed to obtain the vertical polarization radiation function: (12) in, For predicting location frequency The corresponding vertical polarization radiation function, where N is the total number of segments in the external connection cable.

[0036] Furthermore, by expanding the normalized common-mode current coefficient and the vertically polarized effective radiation length vector, we obtain: (13) Based on the normalized common-mode current coefficient, effective horizontal polarization radiation length vector, propagation direction unit vector, propagation distance, and propagation phase of each external connection cable segment, the horizontal polarization radiation contribution generated by each cable segment is coherently superimposed, and the radiation component parallel to the actual ground direction is extracted to obtain the horizontal polarization radiation function vector: (14) in, For predicting location frequency The corresponding horizontal polarization radiation function vector.

[0037] Furthermore, expanding the normalized common-mode current coefficient and the horizontally polarized effective radiation length vector, we obtain: (15) This yields the vertical polarization radiation function. and horizontal polarization radiation function vector This is used to subsequently calculate the vertically polarized radiation intensity and the horizontally polarized radiation intensity, respectively.

[0038] Step 5, Determine the predicted location Vertical polarization normalized radiation intensity at the location and horizontal polarization normalized radiation intensity .

[0039] Based on the distance from the predicted location to the origin and the vertical polarization radiation function, the normalized vertical polarization radiation intensity is obtained: (16) in, For predicting location frequency The corresponding vertically polarized normalized radiation intensity.

[0040] Furthermore, expanding the vertical polarization radiation function, we obtain: (17) Based on the distance from the predicted location to the origin and the horizontal polarization radiation function vector, the normalized horizontal polarization radiation intensity is obtained: (18) in, For predicting location frequency The corresponding horizontally polarized normalized radiation intensity.

[0041] Furthermore, expanding the horizontal polarization radiation function vector, we obtain: (19) This yields the vertically polarized normalized radiation intensity. and horizontal polarization normalized radiation intensity This is used to subsequently calculate the vertical polarization directional gain and the horizontal polarization directional gain, respectively.

[0042] Step 6, Determine the predicted location Vertical polarization directional gain at the location and horizontal polarization directional gain .

[0043] The vertical polarization normalized radiation intensity at the predicted location is correlated with the sum of the vertical and horizontal polarization normalized radiation intensities within the closed far-field directional domain to obtain the vertical polarization directivity gain: (20) in, For predicting location frequency The corresponding vertical polarization directional gain, To define a closed far-field directional domain that surrounds the power electronic converter and its external connecting cables. The integral position within the closed far-field direction domain. It is a solid angle infinitesimal element.

[0044] Furthermore, expanding the normalized radiation intensity of vertical polarization and the normalized radiation intensity of horizontal polarization, we obtain: (twenty one) The horizontal polarization normalized radiation intensity at the predicted location is correlated with the sum of the vertical and horizontal polarization normalized radiation intensities within the closed far-field directional domain to obtain the horizontal polarization directivity gain: (twenty two) in, For predicting location frequency The corresponding horizontal polarization directional gain.

[0045] Furthermore, expanding the normalized radiation intensity of vertical polarization and the normalized radiation intensity of horizontal polarization, we obtain: (twenty three) This yields the vertical polarization directional gain. and horizontal polarization directional gain Both polarization directional gains use the same total radiation normalization reference to characterize the ability of external connecting cables to convert high-frequency common-mode current into vertically polarized radiation and horizontally polarized radiation, respectively, for subsequent calculation of the electromagnetic interference field strength of vertically polarized radiation and horizontally polarized radiation.

[0046] Step 7, Determine the predicted location Vertical polarization radiated electromagnetic interference field strength at the location and horizontal polarized radiated electromagnetic interference field strength The aforementioned steps have yielded two types of polarization directional gains, which are then used as calculation parameters for the two polarization field strengths.

[0047] By correlating the common-mode excitation current flowing into the external connection cable, the radiation efficiency of the external connection cable, the port radiation resistance, and the vertical polarization directivity gain, the vertical polarization radiated electromagnetic interference field strength is obtained: (twenty four) in, For predicting location frequency The corresponding vertically polarized radiated electromagnetic interference field strength amplitude. The wave impedance of the propagation medium, For external connection cables at frequency Radiation efficiency at the lower level This refers to the radiation resistance of the external connection cable port.

[0048] Furthermore, expanding the common-mode excitation current, we obtain: (25) Furthermore, expanding the vertical polarization directional gain, we obtain: (26) By correlating the common-mode excitation current flowing into the external connection cable, the radiation efficiency of the external connection cable, the port radiation resistance, and the horizontal polarization directivity gain, the horizontal polarization radiated electromagnetic interference field strength is obtained: (27) in, For predicting location frequency The corresponding amplitude of the horizontally polarized radiated electromagnetic interference field.

[0049] Furthermore, expanding the common-mode excitation current, we obtain: (28) Furthermore, expanding the horizontal polarization directional gain, we obtain: (29) This yields the electromagnetic interference field strength of vertically polarized radiation. and horizontal polarized radiated electromagnetic interference field strength These two polarization radiation results, representing the power electronic converter and its external connecting cables at the same predicted location and frequency, respectively, provide field strength data for the subsequent formation of vertical polarization prediction spectrum, horizontal polarization prediction spectrum, and determination of dominant polarization.

[0050] Step 8: Determine the predicted spectrum of vertically polarized radiated electromagnetic interference within the target predicted frequency band. Predicted spectrum of horizontally polarized radiated electromagnetic interference .

[0051] Set m frequency sampling points within the target prediction frequency band. , , ..., Based on the vertically polarized radiated electromagnetic interference field strength corresponding to each frequency sampling point, the predicted spectrum of vertically polarized radiated electromagnetic interference is obtained: (30) in, For predicting location Predicted spectrum of vertically polarized radiated electromagnetic interference at [location]. Let j be the j-th frequency sampling point, and m be the total number of frequency sampling points; each group of results consists of the frequency sampling point and the vertically polarized radiated electromagnetic interference field strength at that frequency.

[0052] Based on the horizontally polarized radiated electromagnetic interference field strength corresponding to each frequency sampling point, the predicted spectrum of horizontally polarized radiated electromagnetic interference is obtained: (31) in, For predicting location The predicted spectrum of horizontally polarized radiated electromagnetic interference at a given frequency; each set of results consists of the frequency sampling point and the horizontally polarized radiated electromagnetic interference field strength at that frequency.

[0053] The predicted spectra of vertically polarized radiated electromagnetic interference and the predicted spectra of horizontally polarized radiated electromagnetic interference respectively characterize the relationship between the vertical and horizontal polarization field strengths generated by the power electronic converter and its external connecting cables and the frequency, and serve as the basis for subsequent comparison of the strength of the two polarization radiations, determination of the dominant polarization and identification of the polarization conversion frequency.

[0054] Step 9: Determine the difference between the vertical and horizontal polarization field strengths at each frequency sampling point. Dominant polarization and polarization conversion frequency .

[0055] Based on the vertical and horizontal polarization field strengths corresponding to the same predicted location and the same frequency sampling point, the field strength difference between the two polarizations is obtained: (32) in, For frequency The decibel difference between the vertical polarization field strength and the horizontal polarization field strength.

[0056] Based on the positive and negative relationship between the two polarization field strength differences, the dominant polarization at the corresponding frequency sampling point is determined: (33) in, For frequency The corresponding dominant polarizations are: v indicates that vertical polarization radiation is dominant, h indicates that horizontal polarization radiation is dominant, and e indicates that the field strengths of vertical and horizontal polarization radiation are equal.

[0057] When the signs of the field strength difference between two adjacent frequency sampling points are opposite, the dominant relationship between vertical polarization and horizontal polarization changes between the two frequency sampling points. The determination condition is as follows: (34) Based on the difference in field strength between two adjacent frequency sampling points, the q-th polarization transition frequency is determined using linear interpolation: (35) in, The frequency at which the q-th vertical polarization and horizontal polarization dominance switch occurs within the target frequency band is predicted. , This represents the total number of polarization switching frequencies.

[0058] Step 10: Constructing the prediction result sequence of dual-polarized radiated electromagnetic interference and the set of polarization transition frequencies: Forming predicted location Prediction results sequence of dual-polarized radiated electromagnetic interference at the location and polarization conversion frequency set .

[0059] The vertical polarization prediction spectrum and horizontal polarization prediction spectrum obtained in step 8, as well as the dual-polarization field strength difference and dominant polarization results determined in step 9, are correlated to form a sequence of dual-polarization radiated electromagnetic interference prediction results: (36) in, For predicting location The sequence of prediction results for dual-polarized radiated electromagnetic interference at a given location; each set of prediction results includes the frequency in sequence. Vertical polarization radiated electromagnetic interference field strength Horizontal polarized radiated electromagnetic interference field strength Difference in polarization field strength and dominant polarization .

[0060] Furthermore, all polarization transition frequencies identified within the target prediction frequency band are combined to obtain a set of polarization transition frequencies: (37) in, For predicting location The set of polarization conversion frequencies within the target prediction frequency band.

[0061] The following functions can be achieved using the predicted sequence of dual-polarized radiated electromagnetic interference and the set of polarization conversion frequencies: (1) Independent prediction of the electromagnetic interference spectrum of vertically polarized and horizontally polarized radiation: Based on the vertically polarized field strength corresponding to different frequency sampling points, the predicted spectrum of vertically polarized radiated electromagnetic interference is output: (38) Based on the horizontal polarization field strength corresponding to different frequency sampling points, the predicted spectrum of horizontally polarized radiated electromagnetic interference is output: (39) The two predicted spectra represent the relationship between the vertical polarization field strength and the horizontal polarization field strength as a function of frequency, respectively, and are used to identify the main radiation frequency bands and field strength variation characteristics corresponding to the two polarizations.

[0062] (2) Prediction of dual-polarization radiation characteristics at a specified frequency: For any specified frequency within the target prediction frequency band Output the corresponding dual-polarization radiation characteristics: (40) in, For predicting location Specified frequency The corresponding dual-polarization radiation characteristics include vertical polarization field strength, horizontal polarization field strength, dual-polarization field strength difference, and dominant polarization.

[0063] The difference in dual-polarization field strength at the specified frequency is: (41) The dominant polarization at a specified frequency is determined based on the difference in dual polarization field strength. (42) This determines the relative strength of vertical and horizontal polarization radiation and the main radiation polarization direction at a given frequency.

[0064] (3) Prediction of the dominant polarization variation pattern within the target prediction frequency band: Based on the dominant polarization corresponding to different frequency sampling points, a relationship between the dominant polarization and frequency is established: (43) in, For predicting location Results of dominant polarization changes within the target predicted frequency band.

[0065] When the difference in dual-polarization field intensity at two adjacent frequency sampling points satisfies: (44) The dominance of vertical and horizontal polarization shifts between two adjacent frequency sampling points, with the corresponding polarization transition frequencies being: (45) By combining all polarization conversion frequencies within the target predicted frequency band, we obtain: (46) Based on the correspondence between dominant polarization and frequency and the set of polarization transition frequencies, the frequency ranges in which vertical polarization and horizontal polarization dominate within the target predicted frequency band can be determined, and the frequency locations and corresponding frequency bands where dominant polarization transitions can be identified.

[0066] This method first determines the vertical polarization reference direction and horizontal polarization reference plane based on the actual structure of the power electronic converter and its external connecting cables. The external connecting cables are then divided into several radiating units. Combining the common-mode excitation current, the spatial location of the radiating units, and their propagation characteristics, vertical and horizontal polarization radiation function vectors are established respectively. Then, based on the actual excitation current, cable radiation efficiency, port radiation resistance, and the spatial radiation gain of vertical and horizontal polarization, vertical and horizontal polarization radiated electromagnetic interference (EMI) field strength models are constructed respectively, enabling dual-polarization radiated field strength prediction. Based on the vertical and horizontal polarization field strengths corresponding to sampling points at different frequencies, this method establishes a sequence of dual-polarization radiated EMI prediction results, calculates the dual-polarization field strength difference, determines the dominant polarization direction at each frequency, and identifies the polarization transition frequency between vertical and horizontal polarization. Therefore, this method can independently predict the electromagnetic interference spectrum of vertical and horizontal polarization, predict the dual-polarization radiation characteristics at a specified frequency, and predict the dominant polarization change law within the target prediction frequency band. It can effectively characterize the polarization characteristics in the electromagnetic interference radiated by power electronic converters and provide a basis for electromagnetic compatibility optimization design.

[0067] In summary, this invention addresses the radiated interference characteristics of power electronic converters under high-frequency operating conditions by achieving independent modeling and accurate prediction of the vertical and horizontal polarization components of radiated electromagnetic interference. It effectively overcomes the technical shortcomings of traditional methods, which can only obtain the total amplitude of the radiation field, cannot distinguish polarization components, and are difficult to characterize the evolution law of radiated polarization. It has significant technical advantages and engineering application value.

[0068] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for predicting radiated electromagnetic interference by distinguishing between vertical and horizontal polarization components, characterized in that, Includes the following steps: Step 1: Construct a dual-polarization effective radiation length model: Taking the power electronic converter and its external connecting cables as the objects of radiated electromagnetic interference prediction, determine the vertical polarization reference direction and the horizontal polarization reference plane based on the actual installation status of the equipment and the actual ground direction. Define the unit vector perpendicular to the actual ground upward as the vertical polarization unit vector. Divide the external connection cables into The segment of the radiation unit, according to the first directional length vector of cable segment Determine the vertically polarized effective radiation length vector corresponding to each segment of the cable. and horizontally polarized effective radiation length vector To characterize the geometric effect of cable structure on vertical and horizontal polarization radiation; Step 2: Construct a common-mode current model for external connection cables: based on the common-mode noise voltage at the power electronic converter port. Propagation path impedance between common-mode noise source and external connection cable port and the port impedance presented by external connection cables at the power electronic converter ports. Determine the common-mode excitation current flowing into the external connection cable. Further combining the common-mode current propagation constant Common-mode current reflection coefficient of cable terminals Total cable path length and the external connection cable starting point to the first Path length at the center of the cable segment Determine the first Common-mode current at the center of the cable segment ; Step 3: Construct the vertical and horizontal polarization radiation function models: based on the common-mode current corresponding to each radiation element. Determine the normalized common-mode current coefficient According to the first Center position of cable segment With predicted location The spatial relationship between them determines the propagation distance. Propagation direction unit vector and prediction frequency Corresponding wave number Combined with the effective radiation length vector of vertical polarization Horizontal polarization effective radiation length vector The propagation phase is then used to coherently superimpose the radiation contributions of each segment, yielding the predicted locations. Vertical polarization radiation function at and horizontal polarization radiation function vector ; Step 4: Construct electromagnetic interference field strength models for vertical and horizontal polarization radiation: Based on the vertical polarization radiation function and horizontal polarization radiation function vector Determine the vertically polarized normalized radiation intensity respectively and horizontal polarization normalized radiation intensity The vertical polarization directional gain was obtained based on the same total radiation normalization criterion. and horizontal polarization directional gain ; Further increase the common-mode excitation current Propagation medium wave impedance External connection cable radiation efficiency Port radiation resistance Correlate the corresponding polarization directional gain to obtain the predicted position. Vertical polarization radiated electromagnetic interference field strength at the location and horizontal polarized radiated electromagnetic interference field strength ; Step 5: Construct a dual-polarization spectrum and dominant polarization determination model: Set within the target prediction frequency band Frequency sampling points Based on the vertical polarization radiated electromagnetic interference field strength corresponding to each frequency sampling point and horizontal polarized radiated electromagnetic interference field strength Each of these forms a predicted spectrum of vertically polarized radiated electromagnetic interference. Predicted spectrum of horizontally polarized radiated electromagnetic interference Further calculations were performed on the difference in dual-polarization field strength at each frequency sampling point. and according to The positive and negative relationship determines the dominant polarization at the corresponding frequency sampling point. ; Step 6: Construct a sequence of prediction results for dual-polarized radiated electromagnetic interference: This involves sampling points at each frequency within the target prediction frequency band. Corresponding vertically polarized radiated electromagnetic interference field strength Horizontal polarized radiated electromagnetic interference field strength Difference in polarization field strength and dominant polarization The prediction results of dual-polarized radiated electromagnetic interference are uniformly correlated and sequentially organized according to the frequency sampling order to form a sequence. ; Based on the difference in dual polarization field strength corresponding to adjacent frequency sampling points Changes in the polarization transition frequency that indicate a shift in the dominance of vertical and horizontal polarization. And form a set of polarization conversion frequencies. ; Based on the predicted sequence of dual-polarization radiated electromagnetic interference results and polarization conversion frequency set It enables independent prediction of electromagnetic interference spectra of vertical and horizontal polarization radiation, prediction of dual-polarization radiation characteristics at a specified frequency, and prediction of the dominant polarization change law within the target prediction frequency band.

2. The method for predicting radiated electromagnetic interference by distinguishing between vertical and horizontal polarization components according to claim 1, characterized in that, In step 1, the first Vertical polarization effective radiation length vector corresponding to the cable segment for: （1） Horizontal polarization effective radiation length vector for: （2） In the formula, Represents the vertically polarized unit vector pointing upwards from the real ground; Indicates the first The directional length vector of the external connecting cable segment; and They represent the first The effective radiation length vector of the vertical polarization and the effective radiation length vector of the horizontal polarization of the cable segment.

3. The method for predicting radiated electromagnetic interference by distinguishing between vertical and horizontal polarization components according to claim 1, characterized in that, In step 2, the common-mode excitation current for: （3） No. Common-mode current at the center of the cable segment for: （4） In the formula, Indicates the predicted frequency; This represents the common-mode noise voltage at the port of the power electronic converter; This represents the propagation path impedance between the common-mode noise source and the external connection cable port. This indicates the port impedance presented by the external connection cable at the power electronic converter port; Indicates the connection cable from the start end to the... The path length at the center of the cable segment; Indicates the total path length of the external connection cable; Represents the common-mode current propagation constant; This represents the common-mode current reflection coefficient of the cable termination.

4. The method for predicting radiated electromagnetic interference by distinguishing between vertical and horizontal polarization components according to claim 1, characterized in that, In step 3, the first Normalized common-mode current coefficient corresponding to the cable segment for: （7） No. Center position of cable segment To the predicted position propagation distance for: （9） Propagation direction unit vector for: （10） Prediction frequency Corresponding wave number for: （11） Vertical polarization radiation function for: （12） Horizontal polarization radiation function vector for: （14） In the formula, Indicates the total number of segments in the external connection cable; and These are the magnetic permeability and dielectric constant of the propagation medium, respectively. It represents the imaginary unit.

5. The method for predicting radiated electromagnetic interference by distinguishing between vertical and horizontal polarization components according to claim 1, characterized in that, In step 4, the vertical polarization normalized radiation intensity and horizontal polarization normalized radiation intensity They are respectively: （16） （18） Vertical polarization directional gain for: （20） Horizontal polarization directional gain for: （22） Vertical polarized radiated electromagnetic interference field strength for: （24） Horizontal polarized radiated electromagnetic interference field strength for: （27） In the formula, Ω represents the closed far-field directional domain surrounding the power electronic converter and its external connecting cables; dΩ′ represents the solid angle element; Indicates the wave impedance of the propagation medium; Indicates the frequency of the external connection cable. Radiation efficiency at the lower level; This indicates the radiation resistance of the external connection cable port.

6. The method for predicting radiated electromagnetic interference by distinguishing between vertical and horizontal polarization components according to claim 1, characterized in that, In step 5, frequency sampling points are set in the target predicted frequency band. , and according to and Construct the predicted spectrum of vertically polarized radiated electromagnetic interference respectively Predicted spectrum of horizontally polarized radiated electromagnetic interference ; Dual-polarization field intensity difference at each frequency sampling point for: （32） Based on the difference in bipolar field strength The positive and negative relationship determines the dominant polarization at the corresponding frequency sampling point. : （33） In the formula, v represents that vertical polarization radiation is dominant, h represents that horizontal polarization radiation is dominant, and e represents that the field strengths of vertical and horizontal polarization radiation are equal.

7. The method for predicting radiated electromagnetic interference by distinguishing between vertical and horizontal polarization components according to claim 1, characterized in that, In step 6, the frequencies of each frequency sampling point within the target prediction frequency band are... Vertical polarization radiated electromagnetic interference field strength Horizontal polarized radiated electromagnetic interference field strength Difference in polarization field strength and dominant polarization The prediction results of dual-polarized radiated electromagnetic interference are generated by correlating the results according to the frequency sampling order. : （36） Further, all polarization conversion frequencies identified within the target prediction frequency band will be... By combining them, a set of polarization switching frequencies is formed. : （37） In the formula, Indicates the predicted location The sequence of predicted results for dual-polarized radiated electromagnetic interference at the location; Indicates the first frequency band within the target prediction band The frequency at which the dominant relationship between vertical and horizontal polarization shifts; Indicates the total number of polarization conversion frequencies; Indicates the predicted location The set of polarization conversion frequencies within the target prediction frequency band.

8. The method for predicting radiated electromagnetic interference by distinguishing between vertical and horizontal polarization components according to claim 1, characterized in that, Based on the prediction result sequence of dual-polarized radiated electromagnetic interference According to frequency sampling points Extracting the vertically polarized radiated electromagnetic interference field strength according to the order of change and horizontal polarized radiated electromagnetic interference field strength Forming a predicted spectrum of vertically polarized radiated electromagnetic interference. Predicted spectrum of horizontally polarized radiated electromagnetic interference This enables independent prediction of the electromagnetic interference spectrum of vertically polarized and horizontally polarized radiation.

9. The method for predicting radiated electromagnetic interference by distinguishing between vertical and horizontal polarization components according to claim 1, characterized in that, Based on the prediction result sequence of dual-polarized radiated electromagnetic interference For any specified frequency within the target prediction frequency band Extract the vertically polarized radiated electromagnetic interference field strength corresponding to this frequency. Horizontal polarized radiated electromagnetic interference field strength Difference in polarization field strength and dominant polarization To form a specified frequency The corresponding prediction results of dual-polarization radiation characteristics enable the prediction of the relative strength of vertical and horizontal polarization radiation and the dominant polarization direction at a specified frequency.

10. The method for predicting radiated electromagnetic interference by distinguishing between vertical and horizontal polarization components according to claim 1, characterized in that, Based on the prediction result sequence of dual-polarized radiated electromagnetic interference Sampling points at different frequencies Corresponding dominant polarization Combined with polarization conversion frequency set The method determines the frequency ranges in which vertical and horizontal polarizations dominate within the target prediction frequency band, identifies the frequency locations where the dominant polarizations switch, and realizes the prediction of the dominant polarization change pattern within the target prediction frequency band.

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