A method for measuring and modeling magnetic variables and losses of a magnetic core of arbitrary shape

Abstract

The application discloses a kind of measurement and modeling method of magnetic variable and loss of arbitrary shape magnetic core, belong to magnetic element magnetic variable measurement and loss modeling technical field.This method needs to measure the magnetic variable of standard sample same or equivalent with target magnetic core material under different frequency, magnetic flux density first, identify magnetic hysteresis angle and effective conductivity based on vector magnetic circuit theory;Establish three-dimensional electromagnetic field model including target magnetic core, winding and air domain and carry out grid division, solve each area local magnetic flux density, accordingly configure corresponding parameter, model magnetic hysteresis loss and eddy current loss under sinusoidal excitation, and through the conversion relationship of sinusoidal wave and rectangular wave loss, model the loss of magnetic core under rectangular wave excitation.This application does not need to measure magnetic variable to different shape magnetic core one by one, just by measuring the magnetic variable of standard sample, the accurate modeling of local loss and overall loss of arbitrary shape magnetic core can be realized, suitable for the design, analysis and optimization of magnetic element.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic measurement and core loss modeling of magnetic components, and in particular to a method for identifying vector magnetic circuit parameters using sinusoidal excitation loss data of standard samples, and transferring the vector magnetic circuit parameters to a three-dimensional electromagnetic field model of a target magnetic core with different geometries, so as to calculate the sinusoidal excitation loss and the rectangular wave excitation loss of the same frequency of the target magnetic core. Background Technology

[0002] Core loss is a crucial factor affecting the efficiency, temperature rise, and reliability of high-frequency magnetic components. As power electronic devices evolve towards higher frequencies and higher power densities, the magnetic flux density within the core typically exhibits a significant non-uniform distribution. The core's geometry, winding distribution, corner structure, cylindrical structure, air gap, and edge regions can all cause localized flux concentrations, resulting in differences in hysteresis and eddy current losses across different areas.

[0003] Standard samples, characterized by regular magnetic circuits, ease of testing, and relatively well-defined magnetic flux paths, are commonly used to obtain core loss data of magnetic materials under different frequencies and magnetic flux densities. However, the core loss data measured by standard samples typically reflects the overall or average loss characteristics under regular magnetic circuits and cannot directly reflect the local magnetic flux density distribution and local loss distribution within target cores with different geometries.

[0004] Among the existing methods for calculating magnetic core losses, one type of method directly uses empirical formulas or loss fitting curves to calculate the loss per unit volume, which is difficult to fully reflect the local electromagnetic field differences inside the target magnetic core; another type of method establishes magnetic circuit parameters or finite element models for the magnetic core to be calculated, which usually requires re-acquiring parameters or conducting loss tests for different magnetic core structures, making the calculation process complex and limiting its applicability.

[0005] Vector magnetic circuit theory can describe energy storage, hysteresis dissipation, and eddy current dissipation in magnetic cores using vector magnetic circuit elements such as reluctance, magnetic induction, and magnetocapacitance, and can further obtain parameters such as hysteresis angle and effective conductivity. However, existing techniques mainly calculate or identify relevant parameters in the model of the magnetic core under study itself, without solving the problem of how to use measured loss data of standard samples to transfer hysteresis angle and effective conductivity to three-dimensional electromagnetic field models of target magnetic cores with different geometries.

[0006] Furthermore, practical magnetic components often operate under rectangular wave or other non-sinusoidal excitation. Directly using a rectangular wave as the three-dimensional electromagnetic field input for a complex target magnetic core would increase computational complexity. Therefore, it is necessary to first calculate the three-dimensional electromagnetic field loss of the target magnetic core under sinusoidal excitation, and then obtain the core loss under rectangular wave excitation based on the loss relationship between sinusoidal excitation and rectangular wave excitation at the same frequency. Summary of the Invention

[0007] Technical Problem: The purpose of this invention is to provide a method for measuring and modeling the magnetic variables and losses of magnetic cores of arbitrary shapes, solving the following problems: 1. Identify physically meaningful hysteresis angle and effective conductivity from the sinusoidal excitation loss data of standard samples; 2. Apply the hysteresis angle and effective conductivity to target magnetic cores of arbitrary shapes with different geometries; 3. Based on the local magnetic flux density of each region of the target magnetic core, the parameters after migration are configured in a regionalized manner; 4. Solve for the three-dimensional magnetic field, hysteresis loss, and eddy current loss of the target magnetic core under sinusoidal excitation; 5. Based on the calculation results under sinusoidal excitation, the magnetic core loss magnetic variable under rectangular wave excitation of the same frequency is obtained.

[0008] Technical Solution: To solve the above-mentioned technical problems, the present invention provides a method for measuring and modeling the magnetic variables and losses of magnetic cores of arbitrary shapes, which adopts the following technical solution: S1: Measure the magnetic core loss magnetic variable data of a standard sample under multiple sinusoidal excitation frequencies and multiple magnetic flux densities. The standard sample and the magnetic core to be measured or modeled use the same or equivalent magnetic core material. S2: Based on the vector magnetic circuit theory, the hysteresis angle and effective conductivity of the standard sample are identified according to the core loss data of the standard sample, and the correspondence between the hysteresis angle and the effective conductivity and the magnetic variable parameters of the sinusoidal excitation frequency and magnetic flux density is established. S3: Establish a three-dimensional electromagnetic field model including the target magnetic core, winding region and air region, wherein the geometry of the target magnetic core is different from that of the standard sample; S4: Mesh the three-dimensional electromagnetic field model and solve the three-dimensional electromagnetic field of the target magnetic core under sinusoidal excitation to obtain the local magnetic flux density of each mesh region of the target magnetic core. S5: Based on the local magnetic flux density and sinusoidal excitation frequency of each grid region, determine the hysteresis angle and effective conductivity of each grid region from the parameter correspondence between the hysteresis angle and the effective conductivity and the sinusoidal excitation frequency and magnetic flux density, and configure the hysteresis angle and effective conductivity into the three-dimensional electromagnetic field equation of the corresponding grid region; S6: Based on the three-dimensional electromagnetic field equation configured with the hysteresis angle and the effective conductivity, the hysteresis loss density and eddy current loss density of each grid region of the target magnetic core are modeled, the loss density of each grid region is integrated, and the core loss data of the target magnetic core under sinusoidal excitation is modeled and compared with the measured magnetic core loss magnetic variable. S7: Based on the hysteresis loss and eddy current loss of the target magnetic core under sinusoidal excitation, and the loss conversion relationship between sinusoidal excitation and rectangular wave excitation at the same frequency, the magnetic core loss magnetic variable of the target magnetic core under rectangular wave excitation is modeled and compared with the measured magnetic core loss magnetic variable.

[0009] The standard sample and the target magnetic core have at least one of the same material grade, material composition, manufacturing process, magnetic permeability characteristics, or electrical conductivity characteristics. The standard sample has a simple shape and is convenient for measurement.

[0010] The core loss data includes at least one of the following: active power data, reactive power data, excitation current data, excitation voltage data, or magnetic flux density data of the standard sample under different sinusoidal excitation frequencies and different magnetic flux densities.

[0011] Step S2 includes: determining hysteresis-related parameters based on core loss data under low-frequency or quasi-static sinusoidal excitation, and determining eddy current-related parameters based on the remaining losses after deducting hysteresis loss from the total core loss at the target frequency, so as to obtain the hysteresis angle and the effective conductivity.

[0012] The hysteresis angle is used to characterize the influence of the magnetic core hysteresis effect on the magnetic field response, and the effective conductivity is used to characterize the influence of the magnetic core eddy current effect on the magnetic field response; the hysteresis angle and effective conductivity are obtained by identifying the magnetic core loss data of the standard sample through a vector magnetic circuit equivalent model.

[0013] In step S5, the target magnetic core is divided into multiple calculation regions, and the corresponding hysteresis angle and effective conductivity of each calculation region are determined according to its local magnetic flux density and sinusoidal excitation frequency.

[0014] In step S6, the three-dimensional electromagnetic field equation configured with the hysteresis angle and the effective conductivity is updated with the corresponding hysteresis angle and effective conductivity based on the local magnetic flux density of each calculation region obtained from the current solution result, and the iterative solution continues until the preset convergence condition is met.

[0015] In step S7, the loss conversion relationship is used to convert hysteresis loss and eddy current loss respectively. Hysteresis loss and eddy current loss adopt different waveform conversion relationships. The loss conversion relationship is related to at least one of the following: the duty cycle of the rectangular wave, the magnetic flux density amplitude, the magnetic flux density change rate, the frequency, and the characteristics of the magnetic core material.

[0016] The target magnetic core is at least one of the following: E-type magnetic core, EE-type magnetic core, EI-type magnetic core, U-type magnetic core, UU-type magnetic core, PQ-type magnetic core, pot-type magnetic core, columnar magnetic core, composite magnetic core, or magnetic core with a non-uniform cross-section.

[0017] Beneficial effects: Compared with the prior art, the present invention has at least the following beneficial effects: 1. The standard sample is only used as a source sample for magnetic variable parameters; the target magnetic core can adopt a different geometry than the standard sample. 2. Instead of directly applying the measured total loss or average unit volume loss of the standard sample to the target magnetic core, the magnetic variables of hysteresis angle and effective conductivity identified by the loss data of the standard sample are transferred to the target magnetic core. 3. Magnetic variable parameters are configured according to the local magnetic flux density of each grid region of the target magnetic core, which can reflect the local loss differences caused by the non-uniformity of magnetic flux inside the target magnetic core; 4. By simultaneously coupling the hysteresis effect and the eddy current effect into the three-dimensional electromagnetic field solution process, it is possible to obtain the local loss distribution and the overall loss. 5. The actual three-dimensional field solution uses sinusoidal excitation, and the rectangular wave loss is obtained by conversion of waveforms of the same frequency, which can reduce the computational complexity of directly solving complex non-sinusoidal fields; 6. By measuring the magnetic variable data of standard samples, loss modeling of target magnetic cores with various geometries can be supported, reducing the workload of carrying out complete magnetic variable measurements again for each magnetic core structure. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the overall process of the method of the present invention.

[0019] Figure 2 The parameters are the sinusoidal excitation vector magnetic circuit parameters of the standard sample at the target frequency. Figure 2 In the figure, (a) represents the relationship between permeability and magnetic flux density. Figure 2 In the figure (b), the imaginary part of the permeability converted from hysteresis angle varies with magnetic flux density. Figure 2 (c) represents the relationship between finite conductivity and magnetic flux density.

[0020] Figure 3 A schematic diagram of a three-dimensional model of the target magnetic core 1, winding region 2, and air region 3.

[0021] Figure 4 This is a schematic diagram of the mesh division of a 3D model. Figure 4 (a) in the diagram is a schematic diagram of the grid partitioning of the target magnetic core. Figure 4 (b) in the diagram is a schematic diagram of the mesh partitioning of the winding region. Figure 4 (c) in the diagram is a schematic diagram of the mesh division of the air region.

[0022] Figure 5 A schematic diagram of the three-dimensional electromagnetic field modeling results of the target magnetic core under sinusoidal excitation.

[0023] Figure 6 A schematic diagram of the modeling results of the total loss of the target magnetic core under sinusoidal excitation.

[0024] Figure 7 This is a comparison chart of the calculated and experimental losses of the EE-type magnetic core under actual sinusoidal conditions in Example 1.

[0025] Figure 8 This is a comparison chart of the calculated and experimental losses of the PQ-type magnetic core under actual sinusoidal conditions in Example 2.

[0026] Figure 9 This is a simulation result distribution of hysteresis loss and eddy current loss of the PQ-type magnetic core under actual sinusoidal operating conditions in Example 2. Figure 9 (a) in the diagram is the hysteresis loss density distribution. Figure 9 (b) in the diagram is the eddy current loss density distribution. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. For those skilled in the art, any equivalent substitutions or modifications made without departing from the concept of the present invention should fall within the scope of protection of the present invention.

[0028] First, a standard sample with the same or equivalent core material as the target magnetic core is selected. Sinusoidal excitation is applied to the standard sample under multiple frequencies and multiple magnetic flux densities. The magnetic core loss data and magnetic variables of the standard sample can be measured.

[0029] Secondly, the core loss data of the standard sample is processed based on vector magnetic circuit theory to identify the hysteresis angle and effective conductivity. The hysteresis angle describes the phase change of the magnetic field response caused by the hysteresis effect of the core, while the effective conductivity describes the influence of the eddy current effect on the magnetic field response and loss. Based on the identification results under multiple frequencies and multiple magnetic flux densities, the correspondence between the hysteresis angle, effective conductivity, frequency, and magnetic flux density is established.

[0030] Then, a three-dimensional electromagnetic field model consisting of the target magnetic core, winding region, and air region is established, and the target magnetic core is divided into multiple grid regions. The geometry of the target magnetic core differs from that of the standard sample and can be E-type, EE-type, EI-type, U-type, UU-type, PQ-type, columnar, composite, or other irregular shaped magnetic cores.

[0031] The three-dimensional electromagnetic field model is solved under sinusoidal excitation to obtain the local magnetic flux density of each grid region of the target magnetic core. Based on the local magnetic flux density of each grid region and the sinusoidal excitation frequency, the aforementioned correspondence of magnetic variable parameters is used to determine the hysteresis angle and effective conductivity of each grid region, and these are introduced as local material field parameters into the three-dimensional electromagnetic field governing equations.

[0032] The three-dimensional electromagnetic field control equations, configured with local hysteresis angles and effective conductivity, are solved to obtain the magnetic field quantity, magnetic flux density, and eddy current density of each computational region of the target magnetic core. Furthermore, the hysteresis loss density and eddy current loss density of each computational region are calculated. By integrating the loss density of each computational region, the hysteresis loss, eddy current loss, and total loss magnetic variables of the target magnetic core under sinusoidal excitation can be modeled and compared with the measured magnetic core loss magnetic variables.

[0033] When calculating rectangular wave loss, a sinusoidal excitation frequency identical to the target rectangular wave excitation reference frequency is selected. The sinusoidal excitation loss of the target magnetic core is obtained using the method described above. Then, based on the frequency, duty cycle, and magnetic flux density amplitude of the rectangular wave, combined with Fourier decomposition and the different effects of harmonics on magnetic induction and magnetocapacitance, the magnetic core loss magnetic variable under rectangular wave excitation at the same frequency can be modeled and compared with the measured magnetic core loss magnetic variable through nonlinear superposition. The specific steps are as follows: S1: Measure the magnetic core loss magnetic variable data of the standard sample under multiple sinusoidal excitation frequencies and multiple magnetic flux densities. The standard sample and the magnetic core to be calculated use the same or equivalent magnetic core material. S2: Based on the vector magnetic circuit theory, the hysteresis angle and effective conductivity of the standard sample are identified according to the core loss data of the standard sample, and the correspondence between the hysteresis angle and the effective conductivity and the magnetic variable parameters of the sinusoidal excitation frequency and magnetic flux density is established. S3: Establish a three-dimensional electromagnetic field model including the target magnetic core, winding region and air region, wherein the geometry of the target magnetic core is different from that of the standard sample; S4: Mesh the three-dimensional electromagnetic field model and solve the three-dimensional electromagnetic field of the target magnetic core under sinusoidal excitation to obtain the local magnetic flux density of each calculation region of the target magnetic core; S5: Based on the local magnetic flux density and sinusoidal excitation frequency of each calculation region, determine the hysteresis angle and effective conductivity corresponding to each calculation region from the parameter correspondence between the hysteresis angle and the effective conductivity and the sinusoidal excitation frequency and magnetic flux density, and configure the hysteresis angle and effective conductivity into the three-dimensional electromagnetic field equation of the corresponding calculation region; S6: Based on the three-dimensional electromagnetic field equation configured with the hysteresis angle and the effective conductivity, calculate the hysteresis loss density and eddy current loss density of each calculation region of the target magnetic core, and integrate the loss density of each calculation region. The core loss of the target magnetic core under sinusoidal excitation can be modeled and compared with the measured magnetic core loss magnetic variable. S7: Based on the hysteresis loss and eddy current loss of the target magnetic core under sinusoidal excitation, and the loss conversion relationship between sinusoidal excitation and rectangular wave excitation at the same frequency, the magnetic core loss magnetic variable of the target magnetic core under rectangular wave excitation is modeled and compared with the measured magnetic core loss magnetic variable.

[0034] (I) General Methods

[0035] like Figure 1 As shown, the method for calculating the loss of an arbitrary-shaped magnetic core according to the present invention includes the following stages: 1. Measurement of magnetic variables in the loss data of standard sample sinusoidal excitation; 2. Identification of hysteresis angle and effective conductivity based on vector magnetic circuit theory; 3. Establish a three-dimensional electromagnetic field model of the target magnetic core; 4. Transfer the magnetic variable parameters obtained from the standard sample to each calculation region of the target magnetic core; 5. Solve the three-dimensional electromagnetic field of the target magnetic core under sinusoidal excitation to obtain the local magnetic flux density and local loss; 6. Based on the loss results under sinusoidal excitation, calculate the loss under rectangular wave excitation of the same frequency.

[0036] In this invention, the "standard sample" is a source of magnetic variable parameters used to measure material-related loss data and vector magnetic circuit parameters; the "target magnetic core" is the actual magnetic core that requires three-dimensional electromagnetic field modeling and loss prediction. The target magnetic core uses the same or equivalent magnetic material as the standard sample, but its geometry differs from that of the standard sample.

[0037] Instead of directly assigning the overall loss or average unit volume loss magnetic variables of the standard sample to the target magnetic core, this invention configures the hysteresis angle and effective conductivity magnetic variables identified based on the loss data of the standard sample into the three-dimensional electromagnetic field model of the target magnetic core according to the local magnetic flux density and excitation frequency of each calculation region of the target magnetic core.

[0038] (II) Acquisition of standard sample loss data and parameter identification

[0039] First, select a standard sample made of the same or equivalent material as the target magnetic core. Except for geometry, the standard sample and the target magnetic core should have the same material grade, material composition, manufacturing process, and main electromagnetic properties. Furthermore, the standard sample should have a simple shape and be easy to measure, such as a standard magnetic ring.

[0040] The magnetic core loss and magnetic variables of the standard sample are measured under multiple sinusoidal excitation frequencies and multiple magnetic flux densities. The measurement data may include magnetic variables such as excitation voltage, excitation current, active power, reactive power, excitation frequency, magnetic flux density amplitude, and magnetic core loss. In addition, the effective magnetic path length and effective magnetic path cross-sectional area of ​​the standard sample should also be measured.

[0041] To reduce measurement errors, multiple measurements under the same operating conditions can be performed and averaged. The measurement data should be screened according to the operating conditions, selecting low-frequency or quasi-static data that characterizes hysteresis loss, and high-frequency data for the target calculation frequency. Data at different frequencies should have corresponding magnetic flux density sampling points.

[0042] The purpose of the above data processing is to form a standard sample dataset for vector magnetic circuit parameter identification, rather than directly converting the total loss of the standard sample into the target core loss proportionally.

[0043] Based on vector magnetic circuit theory, the standard sample is equivalent to a vector magnetic circuit model containing magnetic reluctance, magnetic induction, and magnetocapacitance. Magnetic reluctance is used to characterize the magnetic circuit's opposition to magnetic flux, magnetocapacitance is used to characterize the hysteresis effect of the magnetic core, and magnetic induction is used to characterize the eddy current effect.

[0044] Based on the sinusoidal excitation loss data of standard samples at different frequencies and magnetic flux densities, the hysteresis angle and effective conductivity are identified. Specifically, hysteresis-related magnetic variable parameters can be obtained using data from low-frequency or quasi-static operating conditions, and then the eddy current-related magnetic variable parameters can be determined using the difference between the total loss data at the target frequency and the hysteresis loss.

[0045] Based on vector magnetic circuit theory, under quasi-static conditions, the hysteresis angle Represented as: , In the formula, Permeability, The effective magnetic circuit cross-sectional area of ​​the standard sample. The effective magnetic circuit length of the standard sample. For magnetic capacitance, Given the angular frequency, the formula for calculating the magnetron capacitance is: , In the formula, The magnitude of the magnetic flux. For the core loss under quasi-static conditions, the quasi-static condition is determined by: at a certain low frequency Within a certain range, the core loss is almost linear with frequency, and the loss is not only too small to be measured accurately.

[0046] At the target frequency Below, eddy current loss Represented as: , In the formula, This represents the total loss measured at the target frequency.

[0047] Effective conductivity The relationship with eddy current loss can be expressed as: , In one implementation, and This can be further expressed as a function of the magnetic flux density amplitude, and substituted into subsequent electromagnetic field equations for iterative calculation, such as... Figure 2 The figure shows the final standard sample vector magnetic circuit parameters.

[0048] (III) Establishment of a three-dimensional electromagnetic field model of the target magnetic core

[0049] like Figure 3 As shown, a three-dimensional geometric model was established based on the actual structure of the target magnetic core. The three-dimensional geometric model includes at least the target magnetic core 1, the winding region 2, and the air region 3. If necessary, the model may also include an air gap.

[0050] The target magnetic core 1 has a different geometry from the standard sample and can be a UU type, PQ type, EE type, E type, U type, columnar, combined type or magnetic core with non-uniform cross section.

[0051] like Figure 4 As shown, a three-dimensional geometric model mesh is generated for the target magnetic core 1, winding region 2, and air region 3. The target magnetic core 1 is divided into multiple computational regions. Each computational region can record its spatial location, volume, material properties, and local field variables. A sinusoidal excitation boundary is set for the winding region 2, and the sinusoidal excitation can be a sinusoidal current excitation.

[0052] In one implementation, the three-dimensional geometric model is created using modeling software. The magnetic core region, winding region, and air region are exported separately and then meshed. Boundary conditions are set for the excitation inlet and outlet of the winding. The meshing software, model file format, and data file format are not essential limitations of this invention.

[0053] (iv) Magnetic variable parameter transfer and solution of three-dimensional electromagnetic field with sinusoidal excitation

[0054] Under sinusoidal excitation at the target frequency, an initial solution is obtained for the three-dimensional electromagnetic field model of the target magnetic core, yielding the local magnetic flux density for each computational region. For example... Figure 5 As shown, the local magnetic flux density may differ at different locations within the target magnetic core. For example, the central pillar, side pillars, corners, areas near windows, and areas near air gaps may have different local magnetic flux densities. Therefore, the losses or parameters obtained from a standard sample under a single average magnetic flux density cannot be directly applied to the entire target magnetic core. For the first... A computational region, based on its local magnetic flux density The permeability, hysteresis angle, and effective conductivity are determined from the parameter relationships of the standard sample. After updating the parameters, the solution is iteratively solved until final convergence. Finally, different regions of the target magnetic core obtain their corresponding parameters based on their respective local magnetic flux densities, thereby realizing the transfer of standard sample parameters to different computational regions of the target magnetic core.

[0055] The hysteresis angle and effective conductivity of each computational region are incorporated into the three-dimensional electromagnetic field equations of the corresponding region. The magnetic vector potential is used as the basis for this calculation. When the unknown quantity is , the three-dimensional electromagnetic field equations can be summarized as follows: , in, Permeability, It is the hysteresis angle. For effective conductivity, For scalar potential, For source current density, Angular frequency, The imaginary unit, It is a vector differential operator.

[0056] In one implementation, the hysteresis angle is used to correct the phase relationship between the magnetic field strength and the magnetic flux density, and the effective conductivity is used to characterize the reaction of eddy currents on the magnetic field. By configuring both in each computational domain, the hysteresis effect and the eddy current effect can participate in the solution of the three-dimensional magnetic field, rather than just serving as empirical loss correction terms after the field solution.

[0057] Since the permeability, hysteresis angle, and effective conductivity of the magnetic core material may vary with local magnetic flux density, iterative methods are preferred for solving these parameters. 1. Set the initial permeability, hysteresis angle, and effective conductivity; 2. Solving for the three-dimensional electromagnetic field under sinusoidal excitation; 3. Obtain the local magnetic flux density of each computational region; 4. Update the corresponding permeability, hysteresis angle, and effective conductivity based on the local magnetic flux density; 5. Resolve the three-dimensional electromagnetic field; 6. Determine whether the changes in magnetic flux density or loss in adjacent iteration steps satisfy the convergence condition.

[0058] When the preset convergence conditions are met, a stable magnetic field distribution and loss distribution of the target magnetic core are obtained.

[0059] (V) Calculation of core loss under sinusoidal excitation

[0060] The local magnetic flux density, magnetic field strength, and eddy current density of each calculation region of the target magnetic core are obtained based on the three-dimensional electromagnetic field solution results.

[0061] No. The local core loss density of the computational region is expressed as: , in, Indicates the first Hysteresis loss density of each computational region Indicates the first Eddy current loss density in the computational region. For example... Figure 7 The figure shows the total loss distribution of the target magnetic core under sinusoidal excitation.

[0062] The total loss of the target magnetic core under sinusoidal excitation is: , in, Calculate the number of regions for the target magnetic core. For the first The volume of each computational region.

[0063] This allows us to obtain the hysteresis loss, eddy current loss, and total loss of the target magnetic core, and also to obtain the loss distribution in each computational region, such as... Figure 6 As shown.

[0064] (vi) Loss conversion for rectangular waves of the same frequency

[0065] In this invention, the rectangular wave loss calculation is based on the three-dimensional field calculation results under sinusoidal excitation. In actual three-dimensional electromagnetic field solutions, sinusoidal excitation is used, and the rectangular wave need not be directly used as the input excitation for the three-dimensional field model of the target magnetic core.

[0066] The specific steps are as follows: 1. Determine the reference frequency and magnetic flux density amplitude of the target rectangular wave excitation; 2. Select a sinusoidal excitation frequency that is the same as the reference frequency; 3. Calculate the sinusoidal excitation loss of the target magnetic core according to implementation methods four to six; 4. Determine the loss conversion relationship from sinusoidal wave to rectangular wave based on at least one of the following: duty cycle, magnetic flux density amplitude, magnetic flux density change rate, and material properties. 5. Convert the hysteresis loss and eddy current loss under sinusoidal excitation to the hysteresis loss and eddy current loss under rectangular wave excitation respectively; 6. The two converted losses are added together, and the total core loss magnetic variable under rectangular wave excitation is modeled and compared with the measured core loss magnetic variable.

[0067] In one implementation, steps 4-6 specifically involve performing Fourier decomposition on the given rectangular wave, combining magnetic domain theory and Maxwell's equations, considering the different generation mechanisms of hysteresis loss and eddy current loss, and taking into account the different effects of harmonics on magnetocapacitance and magnetic induction, further converting the calculated hysteresis loss and eddy current loss under sinusoidal excitation into fundamental magnetocapacitive reactance and... The magnetic reactance of the subharmonic wave, and the loss under the final rectangular wave excitation. It can be calculated as: , in, for Angular frequency under subharmonics for Magnetic reactance under subharmonics This represents the magnetocapacitive reactance value corresponding to the fundamental frequency. for The effective value of the subharmonic flux. The solution results for the rectangular wave excitation loss are shown in Table 1 below.

[0068] Table 1. Results of rectangular wave excitation loss calculation under 1MHz high-frequency conditions: .

[0069] Example: The following embodiments all employ the aforementioned method; the specific modeling, parameter identification, parameter migration, and loss calculation steps will not be repeated. The purpose of these embodiments is to illustrate that the present invention is applicable to target magnetic cores of different shapes, and to verify its effectiveness through calculation result diagrams or calculation-experiment comparison diagrams.

[0070] Example 1: EE type target magnetic core

[0071] Ferrite EE-type magnetic cores were selected as the target magnetic cores, and standard samples with the same or equivalent materials as EE-type magnetic cores were selected as the source of magnetic variable parameters.

[0072] Following the aforementioned method, the hysteresis angle and effective conductivity magnetic variables identified from the standard sample loss data are transferred to the central column, side column, corner, and other calculation regions of the EE-type target magnetic core to complete the three-dimensional loss calculation under sinusoidal excitation and convert it to obtain the loss under rectangular wave excitation.

[0073] Figure 7 This is a comparison chart of the calculated and experimental losses of the EE-type target magnetic core under actual sinusoidal operating conditions.

[0074] Example 2: PQ type target magnetic core

[0075] PQ-type magnetic cores with magnetic powder were selected as the target magnetic cores, and standard samples with the same or equivalent materials as PQ-type magnetic cores were selected as the source of magnetic variable parameters.

[0076] Following the aforementioned method, the hysteresis angle and effective conductivity identified from the standard sample loss data are transferred to the central column, side column, corner, and other calculation regions of the PQ-type target magnetic core to complete the three-dimensional loss calculation under sinusoidal excitation and convert it to obtain the loss under rectangular wave excitation.

[0077] Figure 8 This is a comparison chart of the calculated and experimental losses of the PQ type target magnetic core under actual sinusoidal operating conditions.

[0078] Figure 9 The simulation results of hysteresis loss and eddy current loss of PQ type target magnetic core under actual sinusoidal operating conditions are shown in the figure.

[0079] As can be seen from the above examples, the present invention uses standard samples as the source of material magnetic variable parameters, and uses the sinusoidal excitation loss data of the standard samples to identify the hysteresis angle and effective conductivity; then, the hysteresis angle and effective conductivity are transferred to the three-dimensional electromagnetic field model of the target magnetic core with different geometric shapes according to the local magnetic flux density and excitation frequency of each calculation region of the target magnetic core.

[0080] The key to this invention lies not in directly calculating the target core loss from the total loss of the standard sample, but in converting the standard sample loss data into vector magnetic circuit parameters that can participate in the solution of the three-dimensional electromagnetic field, and achieving regional parameter transfer across geometric shapes according to the local magnetic field state of the target core. After obtaining the hysteresis loss and eddy current loss of the target core under sinusoidal excitation, the loss conversion relationship between sinusoidal excitation and rectangular wave excitation at the same frequency is further used. The loss magnetic variable of the target core under rectangular wave excitation can be modeled and compared with the measured core loss magnetic variable.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, or combinations made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for measuring and modeling magnetic variables and losses in a magnetic core of arbitrary shape, characterized in that, include: S1: Measure the magnetic core loss magnetic variable data of a standard sample under multiple sinusoidal excitation frequencies and multiple magnetic flux densities. The standard sample and the magnetic core to be measured or modeled use the same or equivalent magnetic core material. S2: Based on the vector magnetic circuit theory, the hysteresis angle and effective conductivity of the standard sample are identified according to the core loss data of the standard sample, and the correspondence between the hysteresis angle and the effective conductivity and the magnetic variable parameters of the sinusoidal excitation frequency and magnetic flux density is established. S3: Establish a three-dimensional electromagnetic field model including the target magnetic core, winding region and air region, wherein the geometry of the target magnetic core is different from that of the standard sample; S4: Mesh the three-dimensional electromagnetic field model and solve the three-dimensional electromagnetic field of the target magnetic core under sinusoidal excitation to obtain the local magnetic flux density of each mesh region of the target magnetic core. S5: Based on the local magnetic flux density and sinusoidal excitation frequency of each grid region, determine the hysteresis angle and effective conductivity of each grid region from the parameter correspondence between the hysteresis angle and the effective conductivity and the sinusoidal excitation frequency and magnetic flux density, and configure the hysteresis angle and effective conductivity into the three-dimensional electromagnetic field equation of the corresponding grid region; S6: Based on the three-dimensional electromagnetic field equation configured with the hysteresis angle and the effective conductivity, the hysteresis loss density and eddy current loss density of each grid region of the target magnetic core are modeled, the loss density of each grid region is integrated, and the magnetic core loss magnetic variable of the target magnetic core under sinusoidal excitation is modeled and compared with the measured magnetic core loss magnetic variable. S7: Based on the hysteresis loss and eddy current loss of the target magnetic core under sinusoidal excitation, and the loss conversion relationship between sinusoidal excitation and rectangular wave excitation at the same frequency, the magnetic core loss magnetic variable of the target magnetic core under rectangular wave excitation is modeled and compared with the measured magnetic core loss magnetic variable.

2. The method according to claim 1, characterized in that, The standard sample and the target magnetic core have at least one of the same material grade, material composition, manufacturing process, magnetic permeability characteristics, or electrical conductivity characteristics.

3. The method according to claim 2, characterized in that, The core loss data includes at least one of the following: active power data, reactive power data, excitation current data, excitation voltage data, or magnetic flux density data of the standard sample under different sinusoidal excitation frequencies and different magnetic flux densities.

4. The method according to claim 3, characterized in that, Step S2 includes: determining hysteresis-related parameters based on core loss data under low-frequency or quasi-static sinusoidal excitation, and determining eddy current-related parameters based on the remaining losses after deducting hysteresis loss from the total core loss at the target frequency, so as to obtain the hysteresis angle and the effective conductivity.

5. The method according to claim 4, characterized in that, The hysteresis angle is used to characterize the influence of the magnetic core hysteresis effect on the magnetic field response, and the effective conductivity is used to characterize the influence of the magnetic core eddy current effect on the magnetic field response; the hysteresis angle and effective conductivity are obtained by identifying the magnetic core loss data of the standard sample through a vector magnetic circuit equivalent model.

6. The method according to claim 1, characterized in that, In step S5, the target magnetic core is divided into multiple calculation regions, and the corresponding hysteresis angle and effective conductivity of each calculation region are determined according to its local magnetic flux density and sinusoidal excitation frequency.

7. The method according to claim 1, characterized in that, In step S6, the three-dimensional electromagnetic field equation configured with the hysteresis angle and the effective conductivity is updated with the corresponding hysteresis angle and effective conductivity based on the local magnetic flux density of each calculation region obtained from the current solution result, and the iterative solution continues until the preset convergence condition is met.

8. The method according to claim 1, characterized in that, In step S7, the loss conversion relationship is used to convert hysteresis loss and eddy current loss respectively. Hysteresis loss and eddy current loss adopt different waveform conversion relationships. The loss conversion relationship is related to at least one of the following: the duty cycle of the rectangular wave, the magnetic flux density amplitude, the magnetic flux density change rate, the frequency, and the characteristics of the magnetic core material.

9. The method according to claim 1, characterized in that, The target magnetic core is at least one of the following: E-type magnetic core, EE-type magnetic core, EI-type magnetic core, U-type magnetic core, UU-type magnetic core, PQ-type magnetic core, pot-type magnetic core, columnar magnetic core, composite magnetic core, or magnetic core with a non-uniform cross-section.

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