A method and computer device for constructing dipole sources based on finding the minimum impedance path.

Abstract

The present invention relates to the field of dipole source construction, and more specifically to a dipole source construction method and computer device based on finding a minimum impedance path. The method includes: determining the composition of a dipole model based on the radiation of a PCB noise source based on multi-level expansion theory, calculating the dipole magnetic field based on the mirror principle and superposition theorem; calculating the initial value of a uniformly distributed dipole array based on the relationship between the distance between the observation point and the radiation source and the magnetic field intensity, and the near-field scanning result; calculating the impedance of the dipole array based on the negative correlation between impedance and current and the positive correlation between dipole moment and current magnitude, and finding the dipole minimum impedance path based on the average distance norm and an improved minimum path algorithm; using a differential evolution algorithm to optimize the amplitude of the dipoles that constitute the minimum impedance path, and evaluating the accuracy of the dipole equivalent source construction. The present invention is suitable for constructing a simplified equivalent radiation source model for a PCB.

Description

Technical Field

[0001] This invention relates to the field of dipole source construction, and more specifically to a method and computer device for constructing dipole sources based on finding the path of minimum impedance. Background Technology

[0002] In modern electronic system design, the types and numbers of electronic devices are constantly increasing, while the size of the devices themselves and the distance between them are constantly decreasing. Therefore, electromagnetic interference has become an increasingly important problem. Electromagnetic radiation obtained through measurement or full-wave simulation includes interference from all emission sources, but it is impossible to determine the radiation amount from a specific source.

[0003] Currently, methods for constructing equivalent dipole sources based on near-field scanning technology are being applied to predict electromagnetic interference effects, and source reconstruction methods based on phaseless near-field scanning have attracted industry attention. Global optimization algorithms can search for optimal solutions across the entire range, and due to their strong versatility, they are more widely used in source modeling problems. Existing iterative source reconstruction methods, when simultaneously searching for dipole position and amplitude, suffer from low efficiency due to the multi-dimensional solution space, requiring long iteration times and potentially yielding inaccurate results. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and computer device for constructing a dipole source based on finding the minimum impedance path, which reduces the computational dimension of the dipole model and improves efficiency and accuracy.

[0005] The present invention achieves the above-mentioned objective by adopting the following technical solution: Firstly, the present invention provides a method for constructing a dipole source based on finding the minimum impedance path, comprising:

[0006] Based on the multi-level expansion theory, the composition of the dipole model is determined according to the noise source radiation of PCB (Printed Circuit Board), and the phaseless magnetic field of the dipole is calculated according to the mirror principle and the superposition theorem.

[0007] The initial values ​​are calculated based on the relationship between the distance between the observation point and the radiation source and the magnetic field strength, and the fact that the near-field scanning results are a uniformly distributed dipole array.

[0008] The impedance of the dipole array is calculated by the negative correlation between impedance and current and the positive correlation between dipole moment and current magnitude. Based on the average distance norm and the improved minimum path algorithm, the minimum impedance path of the dipole is found.

[0009] The amplitude of the dipole that forms the minimum impedance path is optimized using the differential evolution algorithm, and the accuracy of the dipole equivalent source construction is evaluated.

[0010] Furthermore, the calculation of the dipole magnetic field based on the mirror principle and the superposition theorem specifically includes:

[0011] A calculation model for the magnetic field of a single dipole is established. Based on the mirror principle, the amplitude at height h is... The system consisting of a dipole and the ground plane is equivalent to a pair of dipoles at height ±h. The magnetic field of each pair of dipoles at the observation point is expressed as... Where T is the transformation matrix, which can be written as

[0012] A magnetic field calculation model for a dipole array is established, and the magnetic field generated by the equivalent dipole source at the observation point is calculated as follows: Let H be the magnetic field generated by the nth dipole at the sampling point. x,n and H y,n According to the superposition theorem, the magnetic field at the observation point is equal to the sum of the effects of all N dipoles on that observation point, i.e.

[0013] Furthermore, the calculation of initial values ​​based on the uniformly distributed dipole array in the near-field scanning results specifically includes:

[0014] The PCB trace layer plane is divided, and the position (x, y), number M×N and spacing delta of the dipoles are set. Each dipole is located directly below the observation point.

[0015] A near-field probe is used to perform a near-field scan of the PCB circuit board at a set height to obtain the magnetic field data H at that height. x and H y ;

[0016] Based on near-field scanning magnetic field data H x and H y By setting a proportionality coefficient k, the magnitudes M of the x and y components of each dipole are calculated. x M y .

[0017] Furthermore, calculating the impedance of the dipole array through the negative correlation between impedance and current, and the positive correlation between dipole moment and current magnitude, specifically includes:

[0018] By establishing the relationship between the magnitude of a dipole and the impedance between adjacent dipoles, and assuming that there are current paths between all adjacent dipoles, the magnitudes of the currents between dipoles distributed in the x and y directions can be obtained, respectively, along with their amplitudes M. x M y The impedance between adjacent dipoles is positively correlated with the reciprocal of the dipole amplitude.

[0019] Establish the equivalent concept of relative impedance of a dipole array, define the distance norm between adjacent dipoles, and define the distance norm between adjacent dipoles along the x-direction as M. y The reciprocal mean, the distance norm between adjacent dipoles along the y-direction is M. x The mean of the inverses, the total distance norm is defined as the sum of all distance norms on the path connecting two dipoles, and the mean distance norm is defined as the ratio of the total distance norm of the path connecting dipoles to the number of distance norms on the path;

[0020] Establish the relationship between the distance norm and the relative impedance of the dipole array path. According to the definition of the distance norm, the smaller the distance norm, the larger the current between the dipoles. Use the average distance norm of the entire path to evaluate the relative impedance of the path.

[0021] Furthermore, based on the average distance norm and the improved minimum path algorithm, the minimum impedance path for the dipole is found specifically including:

[0022] A method for calculating the minimum impedance path is established. The positions of the input and output ports are set, and the dipole closest to the excitation port is set as the starting point and the dipole closest to the output port is set as the ending point. The path with the minimum total distance norm is found and recorded as the initial minimum path of the average distance norm. The average distance norm of the path is calculated and recorded as the initial minimum value of the average distance norm. Subsequently, the path with the minimum total distance norm is found again, and the average distance norm of this path is calculated. When the new minimum value is less than the recorded minimum value, the recorded minimum value is updated. This process is repeated until convergence, and the minimum impedance path of the dipole is obtained.

[0023] Furthermore, the amplitude optimization of the dipoles forming the minimum impedance path using the differential evolution algorithm specifically includes:

[0024] A differential evolution algorithm is established to pre-optimize the population. The population size is defined as NP. All populations are initialized, and each population is set as a dipole array. Each dipole can be represented by a six-dimensional vector.

[0025] in, Let represent the d-th dipole of the t-th population, and Re(·) and Im(·) represent taking the real and imaginary parts of the complex number, respectively. and The coordinates of the dipole's position are represented. The initial path of the population is the optimized result of the minimum impedance path. The initial amplitude of the population is the initial value of the dipole. First, the first population is set to the dipole distribution after path optimization. Then, the range of values ​​for the size of each dipole in several populations is set, and values ​​are randomly selected within this range.

[0026] The optimization process of the differential evolution algorithm is determined. After initializing the dipole model, the objective function is set as the correlation coefficient based on the accuracy evaluation method of the dipole equivalent source, and the convergence objective is 1. In each iteration, mutation, crossover, and selection operations are performed on NP populations to make the objective function meet the requirements. After the iteration ends, all dipoles are scaled up or down proportionally, and the solution with the smallest mean square error is found as the final result.

[0027] Furthermore, assessing the accuracy of dipole equivalent source construction specifically includes:

[0028] Establish a comparison relationship between the reconstructed phase-free magnetic field and the measured phase-free magnetic field, where M is the number of observation points. and The actual magnetic field obtained by measurement is represented by A, SD represents the variance, and MSE is defined as follows: total This is the total mean square error. and ρ and y are the mean square errors of the magnetic fields in the x and y directions, respectively, where m = 1, 2, ..., M; total Defined as the total correlation coefficient, and Let MSE be the correlation coefficients of the magnetic fields in the x and y directions, respectively. Then, the formula for comparing the reconstructed phase-free magnetic field with the measured phase-free magnetic field is MSE. total =MSE x +MSE y ,

[0029] In a second aspect, the present invention provides a computer device including a memory storing program instructions, wherein when the program instructions are executed, the above-described method for constructing a dipole source based on finding the minimum impedance path is performed.

[0030] The beneficial effects of this invention are as follows:

[0031] This invention can determine the PCB emission structure and rapidly construct a simplified equivalent radiation source model. It can not only construct a dipole equivalent model of the PCB emission structure based on single-layer phaseless near-field scanning, but also the constructed equivalent radiation source model can reflect a more complete emission structure path. By decoupling the calculation of dipole amplitude and position, the computational dimension of the dipole model is reduced. This allows the method to construct an equivalent model using more dipoles while achieving the same accuracy in a shorter time compared to traditional global optimization algorithms, and achieving higher equivalent source accuracy within the same timeframe. Attached Figure Description

[0032] Figure 1 A flow chart of the dipole source construction method based on finding the minimum impedance path provided in the embodiments of the present invention;

[0033] Figure 2 This is a flowchart of the process for finding the path with the smaller average distance norm provided in an embodiment of the present invention;

[0034] Figure 3 This is a flowchart of the truncation operation provided in an embodiment of the present invention;

[0035] Figure 4 A flow chart of a dipole source construction method provided in an embodiment of the present invention;

[0036] Figure 5 A schematic diagram of the W-shaped microstrip line and scanning plane provided in an embodiment of the present invention;

[0037] Figure 6 The distribution diagram of the dipole array after initialization of the W-type microstrip line provided in the embodiment of the present invention;

[0038] Figure 7 The distribution diagram of the dipole array after path optimization of the W-type microstrip line provided in the embodiment of the present invention;

[0039] Figure 8 The final distribution diagram of the dipole array provided in the embodiment of the present invention;

[0040] Figure 9 This is a schematic diagram illustrating the distance norm calculation of a dipole array provided in an embodiment of the present invention;

[0041] Figure 10 This is a schematic diagram illustrating the distance norm calculation of another dipole array provided in an embodiment of the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0043] This invention provides a method for constructing a dipole source based on finding the path of minimum impedance, such as... Figure 1 As shown, it includes:

[0044] Based on the multi-level expansion theory, the composition of the dipole model is determined according to the radiation of PCB noise sources, and the phaseless magnetic field of the dipole is calculated according to the mirror principle and the superposition theorem.

[0045] The initial values ​​are calculated based on the relationship between the distance between the observation point and the radiation source and the magnetic field strength, and the fact that the near-field scanning results are a uniformly distributed dipole array.

[0046] The impedance of the dipole array is calculated by the negative correlation between impedance and current and the positive correlation between dipole moment and current magnitude. Based on the average distance norm and the improved minimum path algorithm, the minimum impedance path of the dipole is found.

[0047] The amplitude of the dipole that forms the minimum impedance path is optimized using the differential evolution algorithm, and the accuracy of the dipole equivalent source construction is evaluated.

[0048] Specifically, the calculation of the phaseless magnetic field of a dipole based on the mirror principle and the superposition theorem includes:

[0049] A calculation model for the magnetic field of a single dipole is established. Based on the mirror principle, the amplitude at height h is... The system consisting of a dipole and the ground plane is equivalent to a pair of dipoles at height ±h. The magnetic field of each pair of dipoles at the observation point is expressed as... Where T is the transformation matrix, which can be written as

[0050] A magnetic field calculation model for a dipole array is established, and the magnetic field generated by the equivalent dipole source at the observation point is calculated as follows: Let H be the magnetic field generated by the nth dipole at the sampling point. x,n and H y,n According to the superposition theorem, the magnetic field at the observation point is equal to the sum of the effects of all N dipoles on that observation point, i.e.

[0051] Specifically, the initial value calculation based on the uniformly distributed dipole array obtained from the near-field scanning results includes:

[0052] The PCB trace layer plane is divided, and the position (x, y), number M×N and spacing delta of the dipoles are set. Each dipole is located directly below the observation point.

[0053] A near-field probe is used to perform a near-field scan of the PCB circuit board at a set height to obtain the magnetic field data H at that height. x and H y ;

[0054] Based on near-field scanning magnetic field data H x and H y By setting a proportionality coefficient k, the magnitudes M of the x and y components of each dipole are calculated. x M y .

[0055] Specifically, calculating the impedance of a dipole array through the negative correlation between impedance and current, and the positive correlation between dipole moment and current magnitude, includes:

[0056] By establishing the relationship between the magnitude of a dipole and the impedance between adjacent dipoles, and assuming that there are current paths between all adjacent dipoles, the magnitudes of the currents between dipoles distributed in the x and y directions can be obtained, respectively, along with their amplitudes M. x M yThe impedance between adjacent dipoles is positively correlated with the reciprocal of the dipole amplitude.

[0057] Establish the equivalent concept of relative impedance of a dipole array, and define the distance norm as the distance norm between adjacent dipoles along the x-direction, and define M as the distance norm between them. y The reciprocal mean, the distance norm between adjacent dipoles along the y-direction is M. x The mean of the inverses, the total distance norm is defined as the sum of all distance norms on the path connecting two dipoles, and the mean distance norm is defined as the ratio of the total distance norm of the path connecting dipoles to the number of distance norms on the path;

[0058] Establish the relationship between the distance norm and the relative impedance of the dipole array path. According to the definition of the distance norm, the smaller the distance norm, the larger the current between the dipoles. Use the average distance norm of the entire path to evaluate the relative impedance of the path.

[0059] Specifically, finding the dipole minimum impedance path based on the average distance norm and the improved minimum path algorithm includes:

[0060] A method for calculating the minimum impedance path is established. The positions of the input and output ports are defined, with the dipole closest to the excitation port as the starting point and the dipole closest to the output port as the ending point. The path with the minimum total distance norm is found and recorded as the initial minimum path for the average distance norm. The average distance norm of this path is calculated and recorded as its initial minimum value. This process is repeated to find the path with the minimum total distance norm and calculate its average distance norm. When the new minimum value is less than the recorded minimum value, the recorded minimum value is updated. This cycle continues until convergence, yielding the minimum impedance path for the dipole. The specific calculation flow is as follows: Figure 2 , Figure 3 As shown, the truncation operation refers to a segment of the original path that is not a passable path.

[0061] Specifically, the amplitude optimization of the dipoles forming the minimum impedance path using the differential evolution algorithm includes:

[0062] A differential evolution algorithm is established to pre-optimize the population. The population size is defined as NP. All populations are initialized, and each population is set as a dipole array. Each dipole can be represented by a six-dimensional vector.

[0063] in, Let represent the d-th dipole of the t-th population, and Re(·) and Im(·) represent taking the real and imaginary parts of the complex number, respectively. and The coordinates of the dipole's position are represented. The initial path of the population is the optimized result of the minimum impedance path. The initial amplitude of the population is the initial value of the dipole. First, the first population is set to the dipole distribution after path optimization. Then, the range of values ​​for the size of each dipole in several populations is set, and values ​​are randomly selected within this range.

[0064] The optimization process of the differential evolution algorithm is determined. After initializing the dipole model, the objective function is set as the correlation coefficient based on the accuracy evaluation method of the dipole equivalent source, and the convergence objective is 1. In each iteration, mutation, crossover, and selection operations are performed on NP populations to make the objective function meet the requirements. After the iteration ends, all dipoles are scaled up or down proportionally, and the solution with the smallest mean square error is found as the final result.

[0065] Specifically, assessing the accuracy of dipole equivalent source construction includes:

[0066] Establish a comparison relationship between the reconstructed phase-free magnetic field and the measured phase-free magnetic field, where M is the number of observation points. and The actual magnetic field obtained by measurement is represented by A, SD represents the variance, and MSE is defined as follows: total This is the total mean square error. and ρ and y are the mean square errors of the magnetic fields in the x and y directions, respectively, where m = 1, 2, ..., M; total Defined as the total correlation coefficient, and Let MSE be the correlation coefficients of the magnetic fields in the x and y directions, respectively. Then, the formula for comparing the reconstructed phase-free magnetic field with the measured phase-free magnetic field is MSE. total =MSE x +MSE y ,

[0067] The present invention will be further described below with reference to specific embodiments.

[0068] like Figure 4 As shown, the embodiments of the present invention relate to a dipole source construction method based on finding the minimum impedance path, used to construct a simplified equivalent radiation source model of a PCB, specifically including the following steps:

[0069] Step 1: Build the PCB working circuit. The PCB model is as follows: Figure 5 As shown, set the PCB operating frequency and adjust the input signal amplitude of the signal source to ensure that the PCB radiated emission intensity is at an appropriate level;

[0070] Step 2: Determine the near-field scanning frequency based on the PCB's operating frequency, define the appropriate near-field scanning area, scanning step size, and scanning height, and use a near-field probe to perform a near-field scan of the PCB to obtain the magnetic field distribution H in a certain area above the PCB. x H y ;

[0071] Step 3: Divide the PCB trace layer plane according to the near-field scanning step size, and set the position (x, y), number M×N and spacing delta of the dipoles. Each dipole is located directly below the observation point.

[0072] Step 4: Using near-field scanning magnetic field data H x H y By arbitrarily setting the proportionality coefficient k, it can be obtained through M = kH ref The magnitudes M of the x and y components of each dipole were calculated. x M y The resulting dipole array is as follows Figure 6 As shown;

[0073] Step 5: Based on the input / output port positions, perform a path finding operation with the smaller average distance norm on the dipole array from Step 4, retaining only the dipoles on this path to obtain the optimized dipole distribution diagram, as shown below. Figure 7 As shown;

[0074] Step 6: Determine the number N of the population to be optimized by the differential evolution algorithm. First, set the first population to the dipole distribution after path optimization. Then, set the range of values ​​for the size of each dipole in the next N-1 populations and randomly select values ​​within this range. Since we know the position distribution of the dipoles, set the last two dimensions of each dipole to constant values ​​and do not participate in iterative optimization.

[0075] Step 7: After model initialization, set the objective function to the correlation coefficient based on the correlation coefficient formula in the accuracy evaluation method for dipole equivalent sources, with a convergence target of 1. After iteration, scale up or down all dipoles proportionally and find the solution with the minimum mean square error as the final result. Figure 8 As shown.

[0076] Specifically, the distance norm mentioned in step five is calculated based on the initial amplitude of the dipole array. A simplified 4-dipole array is shown below. Figure 9 , Figure 10 As shown, the four red dots represent four dipoles numbered 1-4.

[0077] Wherein, the distance norm between 1 and 2 is

[0078] 1 / (2M x1 )+1 / (2M x2 )

[0079] If Figure 9 The yellow path is defined as the connection path between 1 and 2. Therefore, the total distance norm and the average distance norm of this path are both [missing information].

[0080] 1 / (2M x1 )+1 / (2M x2 )

[0081] Similarly, if we take Figure 10 The yellow path is defined as the connecting path between 1 and 2. Therefore, the total distance norm of this path is...

[0082] 1 / (2M x1 )+1 / (2M x3 )+1 / (2M y3 )+1 / (2M y4 )+1 / (2M x4 )+1 / (2M x2 )

[0083] The mean distance norm is:

[0084] [1 / (2M x1 )+1 / (2M x3 )+1 / (2M y3 )+1 / (2M y4 )+1 / (2M x4 )+1 / (2M x2 )] / 3.

[0085] According to the definition of the distance norm, the smaller the distance norm, the larger the current between dipoles. The distance norm has properties similar to impedance. Therefore, this invention uses the average distance norm of the entire path to evaluate the relative impedance of the path. This invention assumes that the positions of the input and output ports are known, setting the dipole closest to the excitation port as the starting point and the dipole closest to the output port as the ending point. Due to the undirected nature of the distance norm definition, interchangeing the starting and ending points does not affect the result. Since current always flows along the path of lowest impedance, this patent argues that among all paths connecting the starting and ending points, the path with the smallest average distance norm is more likely to be the actual path of the current. Therefore, the problem can be transformed into: finding the path between two points where the average distance norm can only be small.

[0086] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method for constructing a dipole source based on finding the minimum impedance path, characterized in that, include: Based on the multi-level expansion theory, the composition of the dipole model is determined according to the radiation of PCB noise sources, and the phaseless magnetic field of the dipole is calculated according to the mirror principle and the superposition theorem. The initial values ​​are calculated based on the relationship between the distance between the observation point and the radiation source and the magnetic field strength, and the fact that the near-field scanning results are a uniformly distributed dipole array. The impedance of the dipole array is calculated by the negative correlation between impedance and current and the positive correlation between dipole moment and current magnitude. Based on the average distance norm and the improved minimum path algorithm, the minimum impedance path of the dipole is found. The amplitude of the dipole that makes up the minimum impedance path is optimized using the differential evolution algorithm, and the accuracy of the dipole equivalent source construction is evaluated. The calculation of the dipole array impedance through the negative correlation between impedance and current, and the positive correlation between dipole moment and current magnitude, specifically includes: By establishing the relationship between the magnitude of a dipole and the impedance between adjacent dipoles, and assuming that there are current paths between all adjacent dipoles, the magnitudes of the currents between dipoles distributed in the x and y directions can be obtained, respectively, along with their amplitudes M. x 、M y The impedance between adjacent dipoles is positively correlated with the reciprocal of the dipole amplitude. Establish the equivalent concept of relative impedance of a dipole array, define the distance norm between adjacent dipoles, and define the distance norm between adjacent dipoles along the x-direction as M. y The reciprocal mean, the distance norm between adjacent dipoles along the y-direction is M. x The mean of the inverses, the total distance norm is defined as the sum of all distance norms on the path connecting two dipoles, and the mean distance norm is defined as the ratio of the total distance norm of the path connecting dipoles to the number of distance norms on the path; Establish the relationship between the distance norm and the relative impedance of the dipole array path. According to the definition of the distance norm, the smaller the distance norm, the larger the current between the dipoles. Use the average distance norm of the entire path to evaluate the relative impedance of the path. Based on the average distance norm and an improved minimum path algorithm, the minimum impedance path for a dipole is found specifically by: A method for calculating the minimum impedance path is established. The positions of the input and output ports are set, and the dipole closest to the excitation port is set as the starting point and the dipole closest to the output port is set as the ending point. The path with the minimum total distance norm is found and recorded as the initial minimum path of the average distance norm. The average distance norm of the path is calculated and recorded as the initial minimum value of the average distance norm. Subsequently, the path with the minimum total distance norm is found again, and the average distance norm of this path is calculated. When the new minimum value is less than the recorded minimum value, the recorded minimum value is updated. This process is repeated until convergence, and the minimum impedance path of the dipole is obtained.

2. The dipole source construction method based on finding the minimum impedance path according to claim 1, characterized in that, The calculation of the phaseless magnetic field of a dipole based on the mirror principle and the superposition theorem specifically includes: A calculation model for the magnetic field of a single dipole is established. Based on the mirror principle, the amplitude at height h is... The system consisting of a dipole and the ground plane is equivalent to a pair of dipoles at height ±h. The magnetic field of each pair of dipoles at the observation point is expressed as... Where T is the transformation matrix, A magnetic field calculation model for a dipole array is established, and the magnetic field generated by the equivalent dipole source at the observation point is calculated as follows: Let H be the magnetic field generated by the nth dipole at the sampling point. x,n and H y,n According to the superposition theorem, the magnetic field at the observation point is equal to the sum of the effects of all N dipoles on that observation point, i.e.

3. The dipole source construction method based on finding the minimum impedance path according to claim 1, characterized in that, The calculation of initial values ​​based on a uniformly distributed dipole array in the near-field scanning results specifically includes: The PCB trace layer plane is divided, and the position (x, y), number M×N and spacing delta of the dipoles are set. Each dipole is located directly below the observation point. A near-field probe is used to perform a near-field scan of the PCB circuit board at a set height to obtain the magnetic field data H at that height. x and H y ; Based on near-field scanning magnetic field data H x and H y By setting a proportionality coefficient k, the magnitudes M of the x and y components of each dipole are calculated. x 、M y .

4. The dipole source construction method based on finding the minimum impedance path according to claim 1, characterized in that, The specific steps of using the differential evolution algorithm to optimize the amplitude of dipoles forming the minimum impedance path include: A differential evolution algorithm is established to pre-optimize the population. The population size is defined as NP. All populations are initialized, and each population is set as a dipole array, with each dipole represented by a six-dimensional vector. in, Let represent the d-th dipole of the t-th population, and Re(·) and Im(·) represent taking the real and imaginary parts of the complex number, respectively. and The coordinates of the dipole's position are represented. The initial path of the population is the optimized result of the minimum impedance path. The initial amplitude of the population is the initial value of the dipole. First, the first population is set to the dipole distribution after path optimization. Then, the range of values ​​for the size of each dipole in several populations is set, and values ​​are randomly selected within this range. The optimization process of the differential evolution algorithm is determined. After initializing the dipole model, the objective function is set as the correlation coefficient based on the accuracy evaluation method of the dipole equivalent source, and the convergence objective is 1. In each iteration, mutation, crossover, and selection operations are performed on NP populations to make the objective function meet the requirements. After the iteration ends, all dipoles are scaled up or down proportionally, and the solution with the smallest mean square error is found as the final result.

5. The dipole source construction method based on finding the minimum impedance path according to claim 1, characterized in that, The assessment of the accuracy of dipole equivalent source construction specifically includes: Establish a comparison relationship between the reconstructed phase-free magnetic field and the measured phase-free magnetic field, where M is the number of observation points. and The actual magnetic field obtained by measurement is represented by A, SD represents the variance, and MSE is defined as follows: total This is the total mean square error. and ρ and y are the mean square errors of the magnetic fields in the x and y directions, respectively, where m = 1, 2, ..., M; total Defined as the total correlation coefficient, and Let MSE be the correlation coefficients of the magnetic fields in the x and y directions, respectively. Then, the formula for comparing the reconstructed phase-free magnetic field with the measured phase-free magnetic field is MSE. total =MSE x +MSE y , 6. A computer device comprising a memory storing program instructions, characterized in that, When the program instructions are executed, the dipole source construction method based on finding the minimum impedance path as described in any one of claims 1-5 is performed.

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