Testing device for high and low temperature magnetic conductivity of annular magnetic core

Abstract

The invention relates to the field of magnetic conductivity simulation calculation, in particular to a device for testing high and low temperature magnetic conductivity of an annular magnetic core. Comprising a simulation module which establishes a short-circuit coaxial cavity model through three-dimensional simulation software, puts a magnetic core with known magnetic conductivity into the established short-circuit coaxial cavity, obtains a port reflection coefficient of the short-circuit coaxial cavity model with the magnetic core, and verifies a calculation process of the magnetic conductivity; the magnetic conductivity acquisition module is used for embedding a magnetic core to be measured into the verified short-circuit coaxial cavity model and calculating the magnetic conductivity of the magnetic core to be measured; and the calculation module obtains a reflection coefficient of the port of the short-circuit coaxial cavity model embedded into the magnetic core to be measured, and solves a real part and an imaginary part of the magnetic conductivity of the magnetic core to be measured according to the reflection coefficient. According to the method, three-dimensional simulation software is applied, a short-circuit coaxial cavity model is constructed, the magnetic core with the known magnetic conductivity is adopted for verification, then the magnetic conductivity of the unknown magnetic core is calculated, and the calculation efficiency of the magnetic conductivity is improved. The method is suitable for obtaining the magnetic permeability of the magnetic core.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of magnetic permeability simulation calculation, and particularly relates to a testing device for high and low temperature magnetic permeability of ring-shaped magnetic core. BACKGROUND

[0002] In the field of electronic information, magnetic permeability testing has become an indispensable means for evaluating the performance and quality control of magnetic materials, electromagnetic shielding effectiveness, and microwave components. In the field of energy, magnetic permeability testing helps to explore the performance of magnetic materials in energy conversion and storage. In the field of electromagnetic compatibility, electromagnetic compatibility refers to the ability of a device or system to function properly in a specified electromagnetic environment without causing unacceptable electromagnetic interference to other devices or systems. As a key parameter for measuring the magnetic properties of materials, the accuracy of the measurement results directly affects the evaluation and optimization of electromagnetic compatibility. By accurately measuring the magnetic permeability of materials, the potential impact of electromagnetic interference can be more effectively predicted and evaluated, so that appropriate measures can be taken to reduce or eliminate interference and ensure the electromagnetic compatibility of devices or systems, providing strong support for the safe, stable, and efficient operation of information technology.

[0003] The measurement technology of electromagnetic parameters of materials can be divided into three categories: lumped parameter circuit method, network parameter method, and resonator method, according to different measurement principles. The lumped parameter circuit method analyzes the internal relationship between device impedance and material electromagnetic parameters by constructing a lumped parameter equivalent circuit model of components, and then deduces the electromagnetic parameters of the measured material. However, this method requires the introduction of stray capacitance, the constructed finite element model lacks universality, and each replacement of inductor coil requires re-modeling, and the solution accuracy of stray capacitance is difficult to ensure.

[0004] The network parameter method solves the dielectric constant and magnetic permeability of the material according to the simultaneous equations of scattering parameters and measured material electromagnetic parameters. The short-circuit reflection method requires numerical methods to solve complex transcendental equations, thereby limiting the lower limit of the use frequency; and the transmission / reflection method needs to pay attention to the air gap problem between the sample and the transmission line conductor, and needs to calibrate the measuring instrument, both of which may adversely affect the measurement results.

[0005] The resonator method uses a resonant cavity to calculate the electromagnetic parameters of the measured material by observing the changes in the resonant characteristics of the resonant cavity. However, this method is only suitable for point frequency or extremely narrow frequency band measurement, and has certain limitations. SUMMARY

[0006] The purpose of the present application is to overcome the shortcomings of the prior art and provide a testing device for high and low temperature magnetic permeability of ring-shaped magnetic core, which improves the efficiency and accuracy of magnetic permeability measurement.

[0007] The application achieves the above-mentioned purpose by adopting the following technical scheme, and provides a device for testing high-low temperature magnetic permeability of a ring-shaped magnetic core, comprising:

[0008] The simulation module is configured to establish a short-circuit coaxial cavity model by using a three-dimensional simulation software, put a magnetic core with known magnetic permeability into the established short-circuit coaxial cavity, and acquire a port reflection coefficient of the short-circuit coaxial cavity model with the magnetic core, so as to verify a calculation process of the magnetic permeability.

[0009] The magnetic permeability acquisition module is configured to embed a to-be-tested magnetic core into the short-circuit coaxial cavity model after verification, and calculate the magnetic permeability of the to-be-tested magnetic core.

[0010] The calculation module is configured to acquire a reflection coefficient of a port of the short-circuit coaxial cavity model with the to-be-tested magnetic core embedded, and solve a real part and an imaginary part of the magnetic permeability of the to-be-tested magnetic core according to the reflection coefficient.

[0011] Further, the simulation module is specifically configured to simulate setting, perform simulation solving by using a frequency domain solver, set a background material as a normal mode, set boundary conditions of each direction of the short-circuit coaxial cavity model as an electric boundary with a tangential electric field of 0, import a real part and an imaginary part of the magnetic permeability changing with frequency when setting the magnetic permeability of the to-be-tested magnetic core, perform N-order fitting on the imported real part and imaginary part of the magnetic permeability by using the three-dimensional simulation software, realize import of the magnetic permeability, set a port as a wave port during simulation, select discrete point sweeping during wideband sweeping simulation, and set frequency samples as equidistant sweeping.

[0012] Further, an impedance of an N-head part of the short-circuit coaxial cavity model is calculated by using a coaxial calculation tool, a concentric positioning ring of the short-circuit coaxial cavity model is placed between the magnetic core and the short-circuit coaxial cavity, the magnetic core is fixed, the magnetic core is in the center of the cavity, and the concentric positioning ring is made of polytetrafluoroethylene material.

[0013] Further, if a cavity height of the coaxial cavity is h, a cavity radius is r0, an inner conductor radius is r i , a height of the magnetic core is h0, an inner radius of the magnetic core is r1, and an outer radius of the magnetic core is r2, a magnetic permeability calculation process of the magnetic core is as follows:

[0014] μ represents the magnetic permeability of the to-be-tested magnetic core, L air is a cavity inductance,

[0015] An impedance of a single-turn coil is a complex value, that is, then the self-inductance L is a complex value, and the magnetic permeability of the to-be-tested magnetic core is:

[0016] ω is an angular frequency, ω=2πf, and μ0 is a vacuum magnetic permeability.

[0017] Furthermore, the calculation module is specifically used to calculate the input impedance of the port, and the calculation method is as follows:

[0018] Where Z0 is the matching impedance, S11 represents the reflection coefficient, and Z in Indicates the input impedance of the port;

[0019] according to but R = real(Z) in ), where imag(Z in () represents the input impedance Z in The imaginary part, real(Z) in () represents the input impedance Z in The real part;

[0020] Substitute the obtained L and R into the permeability The calculation formula is used to solve for the real and imaginary parts of the permeability of the magnetic core under test.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention utilizes 3D simulation software to construct a short-circuited coaxial cavity model. First, the core performance of this model was meticulously calculated and verified to ensure that all parameters met the established stringent requirements. After confirming the short-circuited coaxial cavity's performance met the standards, the magnetic core to be tested was cleverly embedded within the cavity. Again, leveraging the powerful capabilities of the 3D simulation software, the reflection coefficient at the input end was accurately calculated. Based on the reflection coefficient, the permeability information of the magnetic core under test was obtained. This method eliminates the need for complex hardware support or cumbersome experimental procedures; accurate calculation of permeability can be achieved solely through simple 3D simulation design. This significantly expands the application scope of permeability measurement. Attached Figure Description

[0023] Figure 1 This is a structural block diagram of a testing device for the high and low temperature permeability of a toroidal magnetic core provided in an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of a short-circuited coaxial cavity model with an embedded magnetic core under test provided in an embodiment of the present invention;

[0025] Figure 3 This is a reflection coefficient characteristic curve of a high and low temperature short-circuit coaxial cavity provided in an embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of the reflection coefficient of the magnetic core at different temperatures during short-circuit coaxial cavity testing provided in an embodiment of the present invention;

[0027] Figure 5This is a schematic diagram of the real part of the magnetic permeability of a magnetic core at different temperatures, derived from the reflection coefficient of the magnetic core at different temperatures, provided by an embodiment of the present invention.

[0028] Figure 6 This is a schematic diagram of the imaginary part of the magnetic permeability of a magnetic core at different temperatures, derived from the reflection coefficient of the magnetic core at different temperatures, provided by an embodiment of the present invention.

[0029] Figure 7 This is a schematic diagram comparing the real part of the magnetic permeability actually used in the three-dimensional simulation software provided in this embodiment of the invention with the given real part of the magnetic permeability;

[0030] Figure 8 This is a schematic diagram comparing the imaginary part of the magnetic permeability actually used in the three-dimensional simulation software provided in this embodiment of the invention with the given imaginary part of the magnetic permeability. Detailed Implementation

[0031] 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.

[0032] This invention provides a testing device for the high and low temperature permeability of a toroidal magnetic core, such as... Figure 1 As shown, it includes:

[0033] The simulation module is used to build a short-circuited coaxial cavity model using 3D simulation software, insert a magnetic core with known permeability into the built short-circuited coaxial cavity, and obtain the port reflection coefficient of the short-circuited coaxial cavity model with the magnetic core to verify the calculation process of the permeability.

[0034] Selection of short-circuited coaxial cavity:

[0035] Using 3D simulation software according to Figure 2 Establish a short-circuited coaxial cavity model;

[0036] The input impedance of the N-connector is 50 ohms. Therefore, during simulation, it is necessary to use a coaxial calculation tool to calculate the impedance of the N-connector to ensure impedance matching.

[0037] A concentric positioning ring is placed between the magnetic core under test and the short-circuited coaxial cavity to fix the magnetic core under test in the center of the cavity.

[0038] The concentric positioning rings are made of polytetrafluoroethylene (PTFE), which is resistant to high temperatures.

[0039] When choosing an N-type probe, it is necessary to select one that is resistant to high temperatures and has a larger probe diameter, as this will increase its service life.

[0040] Simulation settings for 3D simulation software:

[0041] When using a frequency domain solver for simulation, accuracy and efficiency need to be considered when selecting a solver. Frequency domain solvers are more efficient when solving electrically small devices.

[0042] The permeability acquisition module is used to calculate the permeability of the magnetic core under test after embedding it into a short-circuited coaxial cavity model.

[0043] The coaxial cavity has a cavity height of h, a cavity radius of r0, and an inner conductor radius of r. i The height of the magnetic core to be tested is h0, the inner radius is r1, and the outer radius is r2. Then the permeability of the magnetic core to be tested is:

[0044] L represents the permeability of the magnetic core being tested. air It is a cavity inductor.

[0045] The impedance of a single-turn coil is a complex value, namely... Then the self-inductance is a complex value. The permeability of the magnetic core under test is:

[0046] ω is the angular frequency, ω = 2πf, and μ0 is the free permeability, a constant value of 4π × 10⁻⁶. -7 H / m.

[0047] The calculation module is used to obtain the reflection coefficient of the port of the short-circuited coaxial cavity model embedded in the magnetic core under test, and to solve for the real and imaginary parts of the magnetic permeability of the magnetic core under test based on the reflection coefficient.

[0048] After modeling the short-circuited coaxial cavity and setting up the 3D simulation software, the port reflection coefficient S11 of the short-circuited coaxial cavity with a magnetic core can be obtained. Using the obtained port reflection coefficient, the input impedance of the port can be solved as follows:

[0049] Where Z0 is the matching impedance of 50 ohms, S11 represents the reflection coefficient, and Z in Indicates the input impedance of the port;

[0050] because but:

[0051] R = real(Z) in ), where imag(Z in () represents the input impedance Z in The imaginary part, real(Z) in () represents the input impedance Z in The real part.

[0052] Substitute the obtained L and R into the permeability of the magnetic core to be tested in step S2. The calculation formula is used to solve for the real and imaginary parts of the permeability of the magnetic core under test.

[0053] The invention will be further described in detail below with reference to specific implementation examples.

[0054] Design of short-circuited coaxial cavity:

[0055] Based on the dimensions and specifications of the magnetic core, this invention designs a short-circuit coaxial cavity structure, whose reflection coefficient characteristics are as follows: Figure 3 As shown. Before the magnetic core is installed, the reflection coefficient of the input port of the cavity is almost zero. This phenomenon reveals the perfect matching state between the characteristic impedance of the transmission line and the short-circuit impedance of the coaxial cavity, ensuring the integrity, losslessness, and high stability of signal transmission. The structural dimensions of the short-circuit coaxial cavity closely fit the overall contour of the magnetic core. To ensure the stable placement of the magnetic core, a concentric positioning ring is added around the magnetic core. The inner diameter of this positioning ring precisely matches the outer diameter of the magnetic core, while its outer diameter matches the inner diameter of the short-circuit coaxial cavity. This ingenious design ensures that the magnetic core can be accurately positioned in the core position of the short-circuit coaxial cavity, thereby optimizing the overall performance. In addition, to facilitate the installation and removal of the magnetic core, the height of the concentric positioning ring is deliberately designed to be 1 mm lower than that of the magnetic core. The positioning ring is made of polytetrafluoroethylene (PTFE), which is economical, practical, and has high hardness and high temperature resistance, thus effectively fulfilling its precise positioning function while controlling costs.

[0056] Regarding the N-type connector, this invention employs a 50-ohm matched impedance N-type connector input configuration and connects to a vector network analyzer to achieve accurate signal input and measurement. Specifically, the magnetic core dimensions in this design are an outer diameter of 86 mm, an inner diameter of 56 mm, and a height of 25 mm. Accordingly, the inner diameter of the coaxial cavity is set to 89 mm, and the height is 42 mm.

[0057] Figure 4 The test results of the short-circuited coaxial cavity based on this design are presented, demonstrating the reflection coefficient of the magnetic core under different temperature conditions. It can be clearly observed from the figures that the measured reflection coefficient of the magnetic core exhibits different dynamic changes under different temperature environments. Specifically, the reflection coefficient of the magnetic core decreases as the temperature increases.

[0058] and Figure 5 and Figure 6 The focus is on the real and imaginary parts of the magnetic core permeability, derived from measured core reflection coefficient data using formulas. These data reveal that the core permeability decreases with increasing temperature. This trend closely matches and is consistent with the change in the core reflection coefficient with temperature.

[0059] The permeability characteristics of a magnetic core consist of its real and imaginary parts. In this invention, these permeability data and corresponding frequency information are imported into three-dimensional simulation software for fitting. Figure 7 and Figure 8 The comparison between the imported magnetic permeability data (real and imaginary parts) and the actual data used is presented. The results show that the two have good consistency in the frequency bands used, which fully verifies the consistency between the magnetic permeability data used by the 3D simulation software and the actual application requirements, and also proves the high effectiveness of the simulation.

[0060] This invention innovatively designs a short-circuit coaxial cavity device. By simply placing the magnetic core to be tested inside this device and measuring its reflection coefficient, the permeability of the core can be accurately calculated based on the reflection coefficient value. Experimental results show a high degree of agreement between the permeability data calculated using the reflection coefficient and the permeability data actually used in the 3D simulation software. This finding fully verifies the reliability and effectiveness of this method. For magnetic materials whose permeability data is not yet clearly defined, this method provides a practical approach to accurately determine their permeability, thus providing strong support for the research and application of magnetic materials.

[0061] 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 testing device for the high and low temperature permeability of a toroidal magnetic core, characterized in that, include: The simulation module uses 3D simulation software to build a short-circuited coaxial cavity model. A magnetic core with known permeability is placed into the built short-circuited coaxial cavity, and the port reflection coefficient of the short-circuited coaxial cavity model with the magnetic core is obtained to verify the calculation process of the permeability. The permeability acquisition module embeds the magnetic core under test into the short-circuited coaxial cavity model after verification and calculates the permeability of the magnetic core under test. The calculation module obtains the reflection coefficient of the short-circuited coaxial cavity model port embedded in the magnetic core under test, and solves for the real and imaginary parts of the magnetic permeability of the magnetic core under test based on the reflection coefficient.

2. The testing device for high and low temperature magnetic permeability of a toroidal magnetic core according to claim 1, characterized in that, The simulation module is specifically used for simulation settings. It uses a frequency domain solver for simulation solutions, sets the background material to normal mode, and sets the boundary conditions of the short-circuited coaxial cavity model to electric boundaries with zero tangential electric field in each direction. When setting the permeability of the magnetic core to be tested, the real and imaginary parts of the permeability as a function of frequency are imported. The imported real and imaginary parts of the permeability are fitted to an Nth order using 3D simulation software to achieve the import of the permeability. During simulation, the port is set to a wave port, and the broadband frequency sweep is selected to be a discrete point sweep, while the frequency samples are set to be equally spaced sweeps.

3. The testing device for high and low temperature magnetic permeability of a toroidal magnetic core according to claim 1, characterized in that, The impedance of the N-head portion of the short-circuited coaxial cavity model is calculated using a coaxial calculation tool. The concentric positioning ring of the short-circuited coaxial cavity model is placed between the core under test and the short-circuited coaxial cavity to fix the core under test, so that the core under test is in the center of the cavity. The concentric positioning ring is made of polytetrafluoroethylene.

4. The testing device for high and low temperature magnetic permeability of a toroidal magnetic core according to claim 1, characterized in that, If the cavity height of the short-circuited coaxial cavity is h, the cavity radius is r0, and the inner conductor radius is r... i The core height is h0, the inner radius is r1, and the outer radius is r2. The calculation process for the core permeability is as follows: L represents the permeability of the magnetic core. air It is a cavity inductor. The impedance of a single-turn coil is a complex value, namely... Then the self-inductance L is a complex value. The permeability of the magnetic core is: ω is the angular frequency, ω = 2πf, and μ0 is the permeability of free space.

5. The testing device for high and low temperature magnetic permeability of a toroidal magnetic core according to claim 4, characterized in that, The calculation module is specifically used to calculate the input impedance of the port, and the calculation method is as follows: Where Z0 is the matching impedance, S11 represents the reflection coefficient, and Z in Indicates the input impedance of the port; according to but R = real(Z) in ), where imag(Z in () represents the input impedance Z in The imaginary part, real(Z) in () represents the input impedance Z in The real part; Substitute the obtained L and R into the permeability The calculation formula is used to solve for the real and imaginary parts of the permeability of the magnetic core under test.

Images