A system and method for measuring remanent magnetism of ferromagnetic body

Abstract

The present invention discloses a system and method for measuring the remanent magnetism of ferromagnetic materials, belonging to the field of electromagnetic parameter measurement technology. The system includes a fluxgate sensor array, a data integrator, and a host computer; the fluxgate sensor is used to measure the magnetic induction intensity and transmit it to the host computer; the host computer is used to obtain the residual magnetization intensity matrix and the magnetic induction intensity matrix, thereby calculating the conversion matrix, and combining the uniqueness of the conversion matrix to verify the uniqueness of the remanent magnetization intensity of the desired ferromagnetic material; under the premise that the geomagnetic field can be ignored, according to the constitutive relationship B=μ0(H+M), the magnitude and direction of the remanent magnetization component of the material can be obtained and displayed in real time from the remanent magnetization intensity. The measurement system and measurement method proposed in the present invention measure the remanent magnetism of ferromagnetic materials by combining a magnetic field sensor with a COMSOL Multiphysics model, and have the advantages of simple operation, real-time display, reliable results, applicability to measuring the remanent magnetism of ferromagnetic materials with irregular shapes or uneven remanent magnetism distribution, and clear and novel principles.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic parameter measurement, and more specifically, relates to a system and method for measuring the residual magnetism of a ferromagnetic body. Background Art

[0002] In power systems, when a newly built substation's main transformer is put into operation, closing the no-load transformer generates a large inrush current, significantly impacting the power grid. When the current flowing through inductive devices with iron cores, such as transformers, reactors, and current transformers, is interrupted, residual magnetism forms within the core. This residual magnetism shifts the starting operating point of the current transformer's excitation curve, accelerating the core's magnetic saturation. This results in excessive inrush currents, approximately 6 to 8 times the rated current, when closing the circuit without load. This compromises the mechanical stability and insulation strength of the transformer windings, seriously impacting the transformer's safety and stability in power grid applications. Furthermore, the residual magnetism of current transformers in power systems can affect transformer errors, thereby affecting their metering and protection performance, and leading to discrepancies in energy metering and trade settlement. To prevent damage to transformer windings and insulation in power systems and the impact of residual magnetism on power transformer metering accuracy, research is needed to measure the residual magnetism of ferromagnetic materials and facilitate residual magnetism measurement and demagnetization of inductive devices with iron cores.

[0003] In actual engineering, there is no clear and mature method for measuring the residual magnetism of iron cores at home and abroad, and various theories and models need further research. The existing residual magnetism measurement methods mainly include the following:

[0004] 1) Empirical estimation method. In engineering, it is generally believed that the residual magnetism of a transformer after testing or operation is generally in the range of 20% to 80% of the saturation flux. This method relies solely on engineering experience and cannot accurately determine the value and direction of the core residual magnetism;

[0005] 2) Residual magnetism measurement based on transformer leakage flux. This method uses a fluxgate sensor to measure the transformer's leakage flux. The residual magnetism of the core is then measured by establishing a transfer function between the magnitude of the transformer's leakage flux and the magnitude of the core's residual magnetism. Inaccuracies in current measurement with this method can lead to inaccuracies in the transfer function, ultimately affecting the determination of the core's residual magnetism. Furthermore, for three-phase power transformers, establishing the transfer function is even more difficult because the residual magnetism of each phase varies.

[0006] 3) Residual magnetization measurement based on inrush current. By comparing the differences in inrush current under different remanent magnetization conditions, a relationship between remanent magnetization and inrush current is established, and the remanent magnetization of the core is obtained. This method requires winding a coil to measure the current flow, which is relatively inconvenient. The relationship between inrush current and remanent magnetization obtained through data fitting is not physically meaningful, and this method is only applicable to ferromagnetic materials with regular shapes. Summary of the Invention

[0007] In view of the defects of the prior art, the purpose of the present invention is to provide a measurement system and method for the remanent magnetism of ferromagnetic materials, aiming to solve the problems of the existing ferromagnetic remanent magnetism measurement operation being complicated, the inability to determine the remanent magnetism direction, and the inability to measure non-uniform remanent magnetism.

[0008] In order to improve the deficiencies in the above-mentioned existing residual magnetism measurement technology, the present invention proposes a measurement system and method for the residual magnetism of a ferromagnetic body. The initial magnetic field matrix B0 generated by a ferromagnet placed at a spatial point A at a spatial point B is measured by a fluxgate sensor array and transmitted to a host computer via a data integrator. A finite element model of the same size as the measurement experiment is established in the COMSOL Multiphysics software in the host computer, the residual magnetization intensity of the ferromagnetic material in the model is set, and the magnetic induction intensity data of the measuring point at the sensor is read to obtain the residual magnetization intensity matrix M and the spatial magnetic induction intensity matrix B. By substituting the obtained residual magnetization intensity matrix M and the spatial magnetic induction intensity matrix B into the MATLAB program, the conversion matrix A from the residual magnetization intensity to the magnetic induction intensity is calculated and its full rank is verified. Since the conversion matrix A is unique after the geometric shape and geometric relationship are determined, there is a one-to-one correspondence between the residual magnetization intensity and the magnetic induction intensity. After inverting it and combining it with the initial magnetic field matrix B0 transmitted to the host computer, the magnitudes of the three components of the residual magnetization intensity X, Y, and Z can be obtained. Combined with the constitutive relationship B=μ0(H+M), where H is the magnetic field intensity, M is the magnetization intensity, μ0 is the vacuum magnetic permeability, and B is the magnetic induction intensity, under the premise that the geomagnetic field can be ignored, the magnitudes and directions of the three components of the material's remanent magnetism can be obtained and displayed on the host computer.

[0009] The ferromagnetic remanence measurement system provided by the present invention comprises a fluxgate sensor array, a data integrator, and a host computer;

[0010] The fluxgate sensor array measures the three components of the magnetic induction intensity X, Y, and Z for a specified spatial point and transmits them to the host computer through a data integrator;

[0011] The host computer is used to receive magnetic field data from the fluxgate sensor array, obtain the initial magnetic field matrix B0, combine the conversion matrix A calculated by the residual magnetization matrix M and the spatial magnetic induction intensity B, calculate the residual magnetization matrix M0 of the ferromagnetic material, and finally obtain the remanence of the material by combining the constitutive relationship.

[0012] Furthermore, the host computer includes a data receiving module, a COMSOL Multiphysics finite element software module and a MATLAB calculation module; the data receiving module is used to receive the magnetic induction intensity measured by the fluxgate sensor array; the COMSOL Multiphysics finite element software module is used to establish a proportional finite element model, divide the corresponding domains according to actual conditions, wherein the number of domains is the number of uniform remanent magnetization segments n, and the size of the remanent magnetization intensity matrix M and the spatial magnetic induction intensity matrix B is determined by the number of domains n, and by modifying the initial magnetization intensity in three directions of different domains, a full-rank remanent magnetization intensity matrix M and a corresponding spatial magnetic induction intensity matrix B are obtained; the MATLAB calculation module is used to combine the remanent magnetization intensity matrix M and the spatial magnetic induction intensity matrix B to calculate a full-rank conversion matrix A, combine the initial magnetic field matrix B0 and the conversion matrix A to calculate the remanent magnetization matrix M0 of the ferromagnetic material, and calculate the remanence of the material in combination with the constitutive relationship.

[0013] Furthermore, the number of sensors in the fluxgate sensor array is equal to the number n of uniform residual magnetization segments.

[0014] The present invention also provides a method for measuring the remanence of a ferromagnetic body, comprising the following steps:

[0015] (1) Place the ferromagnetic object at the far end of the measurement point, and record the measured magnetic field matrix as B 01 , then place the ferromagnetic object near the measuring point, and record the measured magnetic field matrix as B 02 , then the initial magnetic field matrix generated by the ferromagnetic remanence is B0=B 02 -B 01 ;

[0016] (2) Establish a proportional finite element model and divide the corresponding domains according to the actual situation. The number of domains is the number of uniform remanent magnetization segments n. The size of the remanent magnetization matrix M and the spatial magnetic induction matrix B is determined by the number of domains n. By modifying the initial magnetization in three directions of different domains, the full-rank remanent magnetization matrix M and the spatial magnetic induction matrix B are obtained.

[0017] (3) Combining the residual magnetization matrix M and the spatial magnetic induction matrix B, the full-rank conversion matrix A is calculated; combining the initial magnetic field matrix B0 and the conversion matrix A, the residual magnetization matrix M0 of the ferromagnetic material is calculated, and combined with the constitutive relationship, the remanence of the material is calculated.

[0018] The spatial magnetic field generated by the ferromagnet is measured by a fluxgate sensor array and transmitted to the host computer. Combining the proportional COMSOL Multiphysics finite element model with the conversion matrix calculated by the MATLAB program and the initial magnetic field measured experimentally, the components of the ferromagnetic residual magnetization intensity in the X, Y, and Z directions are calculated. Combined with the constitutive relationship, the components of the remanent magnetization in the X, Y, and Z directions are obtained, thereby obtaining the magnitude and direction of the ferromagnetic remanent magnetization component and displaying them on the host computer.

[0019] For a uniform ferromagnetic body divided into n segments, the size of the initial magnetization intensity matrix M0 to be solved is 3n×1. n three-phase sensors are required to measure the spatial magnetic field. At this time, the size of the conversion matrix A is 3n×3n. Therefore, a full-rank magnetization intensity matrix M of 3n×3n and a corresponding 3n×3n spatial magnetic induction intensity matrix B need to be obtained in the COMSOL Multiphysics model.

[0020] Preferably, the steps for measuring the initial magnetic field generated by a ferromagnet placed at a spatial point A at an arbitrary spatial point B are as follows: the ferromagnet is placed at a point C far away from the spatial point B. Since the spatial points B and C are far apart, the residual magnetism of the ferromagnet on B can be ignored. x0 、B y0 and B z0 The fluxgate sensor is used to measure the magnetic induction intensity B at the space point B at this time. x1 、B y1 and B z1 , then place the ferromagnetic body at point A in space, and measure the magnetic induction intensity B at point B in space at this time x2 、B y2 and B z2 , then the initial magnetic field B generated by the ferromagnetic body at point A at point B in space is x0 =B x2 -B x1 , B y0 =B y2 -B y1 , B z0 =B z2 -B z1 , which can be written as the initial magnetic field matrix B0.

[0021] Preferably, the origin of the spatial coordinate system is specified, the geometric dimensions of the ferromagnetic body and the coordinates of the spatial points are measured, and a proportional model is established in COMSOL Multiphysics software.

[0022] Preferably, the remanence is linearly related to the initial magnetization intensity, the initial magnetization intensity is linearly related to the initial magnetization current, the initial magnetization current is linearly related to the initial magnetic field size, and therefore the remanence is linearly related to the initial magnetic field.

[0023] Preferably, for the following linear equations:

[0024] B = AM + CB is the spatial magnetic induction matrix, M is the residual magnetization matrix, A is the conversion matrix, and C is the bias matrix. For the model that calculates the residual magnetization, the bias matrix C is a zero matrix. It is known that the conversion matrix A is unique. If the conversion matrix A is full rank, then the residual magnetization M and the spatial magnetic induction B are one-to-one corresponding. For a ferromagnetic material with uniform residual magnetization, the number of unknown variables is 3, which are the components of the residual magnetization in the X direction M x , the component M in the Y direction y and the component M in the Z direction z , so at this time the size of the residual magnetization intensity matrix M is 3×1, and only the size of the spatial magnetic induction intensity matrix B needs to be 3×1 to make the conversion matrix A full rank. Therefore, at this time, only one fluxgate sensor is needed to measure the magnetic induction intensity in the X, Y, and Z directions of the spatial point.

[0025] Preferably, the residual magnetization intensity components of the ferromagnetic material in the X, Y, and Z directions are modified in the established finite element model, and the magnetic induction intensity components in the X, Y, and Z directions at the fluxgate sensor in the model are read.

[0026] Preferably, the size of B is 3×1, the size of M is 3×1, and the size of the transformation matrix A is 3×3, which can be expressed as:

[0027]

[0028] To obtain the transformation matrix A, we need to take A 11 To A 33 For these nine values, each set of initial remanent magnetization and corresponding spatial magnetic induction has three sets of values. Therefore, in the COMSOL Multiphysics finite element model, three sets of initial remanent magnetization and corresponding spatial magnetic induction need to be calculated, resulting in a total of nine sets of values. Substituting these into the MATLAB program for solving the linear equations, the nine values ​​in the transformation matrix A can be calculated.

[0029] Preferably, it is verified in the MATLAB program that the conversion matrix A is full rank. Combined with the uniqueness of the conversion matrix A, it can be shown that the residual magnetization intensity corresponds one-to-one to the spatial magnetic induction intensity, and A is reversible.

[0030] Preferably, for the following formula:

[0031] B=AM

[0032] Multiply both sides of the equal sign by A -1 , we can get the expression of residual magnetization M.

[0033] M=A-1 B

[0034] Preferably, the experimentally measured initial magnetic field matrix B0 at point B is substituted into the above formula to calculate the residual magnetization matrix M0 of the ferromagnetic material. Substituting the three components of the residual magnetization into the constitutive relationship, the three components of the remanent magnetization and the direction of the remanent magnetization can be obtained.

[0035] Preferably, the above is a method for measuring the uniform remanence of a ferromagnetic body, and the following is a method for measuring the segmented uniform remanence of a ferromagnetic body.

[0036] Preferably, for ferromagnetic materials with uniform remanent magnetization, the remanent magnetization measurement method is as follows: Based on the actual remanent magnetization segmentation, the model geometry is divided into corresponding domains in a COMSOL Multiphysics finite element model. Assuming the actual number of segments of the ferromagnet is n, the finite element model is also geometrically divided into n corresponding domains. In this case, the remanent magnetization matrix M is 3n×1 in size. Therefore, to convert the matrix A to full rank, the spatial magnetic induction matrix B must also be 3n×1 in size. In the measurement experiment, n fluxgate sensors are arranged to measure 3n initial magnetic field component values, obtaining an initial magnetic field matrix B0 of 3n×1 in size. In the finite element model, magnetic field data points are also set at each fluxgate sensor to read data, obtaining a spatial magnetic induction matrix B of 3n×1 in size.

[0037] Preferably, let N = 3n, then the conversion matrix A can be expressed as:

[0038]

[0039] To obtain the transformation matrix A, we need to take A 11 To A NN This 9n 2 There are 3n sets of values ​​for each set of initial remanent magnetization and the corresponding spatial magnetic induction. Therefore, in the COMSOL Multiphysics finite element model, 3n sets of initial remanent magnetization and the corresponding spatial magnetic induction need to be calculated, and a total of 9n values ​​are obtained. 2 By substituting the values ​​of the group into the MATLAB program for solving the linear equations, the 9n in the transformation matrix A can be calculated. 2 values.

[0040] Preferably, the conversion matrix A is verified to be full rank in a MATLAB program. Combined with the uniqueness of the conversion matrix A, it is shown that the residual magnetization intensity corresponds one-to-one to the spatial magnetic induction intensity, and A is reversible.

[0041] Preferably, for the following formula:

[0042] B=AM

[0043] Multiply both sides of the equal sign by A-1 , we can get

[0044] M=A -1 B

[0045] Preferably, the experimentally measured initial magnetic field matrix B0 of size 3n×1 is substituted into the above formula to calculate the residual magnetization matrix M0 of the ferromagnetic material. Substituting the 3n components of the residual magnetization into the constitutive relationship, the 3n components of the remanent magnetization and the direction of the remanent magnetization can be obtained.

[0046] Compared with the prior art, the above technical solutions proposed by the present invention can achieve the following:

[0047] Beneficial effects:

[0048] 1. The measurement system and method for the remanent magnetism of ferromagnets provided by the present invention are suitable for measuring non-uniformly distributed remanent magnetism. Compared with the measurement method for uniformly distributed remanent magnetism of ferromagnets, there are three differences: ① the number of sensors is increased from 1 to n, ② the size of the remanent magnetization intensity matrix M and the spatial magnetic induction intensity matrix B in the COMSOL Multiphysics finite element model is changed from 3×1 to 3n×1, and ③ the corresponding conversion matrix is ​​recalculated in the already written MATLAB program. This method provides a new method and idea for measuring non-uniformly distributed remanent magnetism.

[0049] 2. The conversion matrix is ​​automatically calculated using COMSOL Multiphysics finite element software. Under certain geometric relationships and other conditions, the relationship between remanence and magnetic induction intensity at a field point is unique and physically meaningful. However, due to the irregular physical properties of ferromagnetic materials, the conversion matrix is ​​not easy to directly integrate. Using finite element software can effectively circumvent this shortcoming. Since only the geometric shape, geometric relationships, and remanence need to be considered, finite element software has low degrees of freedom, fast calculation speed, and high accuracy.

[0050] 3. The measurement experiment of the remanent magnetism of ferromagnetic materials provided by the present invention is simple and easy. It only needs to use a specified number of sensors to measure the magnetic field components at the field point, without the need for complex operations such as winding coils and changing the current. This avoids the inconvenience of winding coils caused by the complex shape of ferromagnetic materials.

[0051] 4. For the same ferromagnetic body and a certain field point, the conversion relationship is fixed, which also means that the conversion matrix is ​​unique. After calculating it in MATLAB, the same conversion matrix can always be used to solve the ferromagnetic body. Before solving, it is only necessary to measure the magnetic field at the field point with a sensor to obtain the initial magnetic field matrix. In other words, this method has the advantages of being fast, convenient, and displaying in real time.

[0052] 5. The method for measuring the remanence of a ferromagnetic body provided by the present invention can obtain the components of the remanence in the three directions of X, Y, and Z, so the accurate direction of the remanence can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 Schematic diagram of the system for measuring the remanent magnetism of ferromagnetic objects according to the present invention;

[0054] Figure 2 It is a flow chart of the method for measuring the remanent magnetism of a ferromagnetic body according to the present invention;

[0055] Figure 3 Schematic diagram of an experiment for measuring uniform remanence of a ferromagnetic body according to the present invention;

[0056] Figure 4 It is a schematic diagram of the experiment of measuring the segmented uniform remanence of a ferromagnetic body according to the present invention. DETAILED DESCRIPTION

[0057] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0058] The ferromagnetic remanence measurement system provided by the present invention comprises a fluxgate sensor array, a data integrator, and a host computer;

[0059] The fluxgate sensor array measures the three components of the magnetic induction intensity X, Y, and Z for a specified spatial point and transmits them to the host computer through a data integrator;

[0060] The host computer is used to receive magnetic field data from the fluxgate sensor array, obtain the initial magnetic field matrix B0, combine the conversion matrix A calculated by the residual magnetization matrix M and the spatial magnetic induction intensity B, calculate the residual magnetization matrix M0 of the ferromagnetic material, and finally obtain the remanence of the material by combining the constitutive relationship.

[0061] Furthermore, the host computer includes a data receiving module, a COMSOL Multiphysics finite element software module and a MATLAB calculation module; the data receiving module is used to receive the magnetic induction intensity measured by the fluxgate sensor array; the COMSOL Multiphysics finite element software module is used to establish a proportional finite element model, divide the corresponding domains according to actual conditions, wherein the number of domains is the number of uniform remanent magnetization segments n, and the size of the remanent magnetization intensity matrix M and the spatial magnetic induction intensity matrix B is determined by the number of domains n, and by modifying the initial magnetization intensity in three directions of different domains, a full-rank remanent magnetization intensity matrix M and a corresponding spatial magnetic induction intensity matrix B are obtained; the MATLAB calculation module is used to combine the remanent magnetization intensity matrix M and the spatial magnetic induction intensity matrix B to calculate a full-rank conversion matrix A, combine the initial magnetic field matrix B0 and the conversion matrix A to calculate the remanent magnetization matrix M0 of the ferromagnetic material, and calculate the remanence of the material in combination with the constitutive relationship.

[0062] Furthermore, the number of sensors in the fluxgate sensor array is equal to the number n of uniform residual magnetization segments.

[0063] The present invention also provides a method for measuring the remanence of a ferromagnetic body, comprising the following steps:

[0064] (1) Place the ferromagnetic object at the far end of the measurement point, and record the measured magnetic field matrix as B 01 , then place the ferromagnetic object near the measuring point, and record the measured magnetic field matrix as B 02 , then the initial magnetic field matrix generated by the ferromagnetic remanence is B0=B 02 -B 01 ;

[0065] (2) Establish a proportional finite element model and divide the corresponding domains according to the actual situation. The number of domains is the number of uniform remanent magnetization segments n. The size of the remanent magnetization matrix M and the spatial magnetic induction matrix B is determined by the number of domains n. By modifying the initial magnetization in three directions of different domains, the full-rank remanent magnetization matrix M and the spatial magnetic induction matrix B are obtained.

[0066] (3) Combining the residual magnetization matrix M and the spatial magnetic induction matrix B, the full-rank conversion matrix A is calculated; combining the initial magnetic field matrix B0 and the conversion matrix A, the residual magnetization matrix M0 of the ferromagnetic material is calculated, and combined with the constitutive relationship, the remanence of the material is calculated.

[0067] The present invention will be further described below by taking the measurement of the uniform remanence of a ferromagnetic body in three sections as an example.

[0068] like Figure 1 Shown with Figure 2As shown in the figure, after determining the number of segments n of the ferromagnet, the geometric dimensions of the ferromagnet are measured and measurement points are selected to obtain the initial magnetic field. This is then transmitted to the host computer via a data integrator to obtain the initial magnetic field matrix B0. A proportional finite element model is established in the COMSOL Multiphysics finite element module on the host computer and the corresponding domains are divided to obtain the remanent magnetization matrix M and the spatial magnetic induction matrix B. After verifying the full rank of M, the transformation matrix A is obtained. The remanent magnetization matrix M0 is then derived from the initial magnetic field matrix B0 and the transformation matrix A. Finally, the remanent magnetization of the ferromagnet is obtained by combining the constitutive relations and given conditions.

[0069] Figure 3 Here n=1, which is only applicable to the measurement of remanent magnetism of uniform ferromagnetic materials.

[0070] for Figure 4 ferromagnet, n=3.

[0071] Define the origin of the spatial coordinate system so that the three spatial field points B, B', and B" are asymmetrically distributed to avoid the situation where the transformation matrix A is not full of rank due to symmetry. Measure the geometric dimensions of the ferromagnetic body and the coordinates of the spatial points A, B, B', and B". Place sensors 1 to 3 at B, B', and B", respectively. First, place the ferromagnetic body at point C far away and measure the magnetic field components of B, B', and B", and obtain a magnetic field matrix B of size 9×1. 01 , then place the ferromagnetic body at point A, measure the magnetic field components of B, B', and B", and obtain the magnetic field matrix B of size 9×1 02 , then the initial magnetic field matrix B0=B 02 -B 01 , and transmitted to the host computer via the data transmission line.

[0072] In COMSOL Multiphysics, a proportional model was created and the corresponding domains were divided. For this example, n = 3. Each uniform segment of remanent magnetization has three unknown components: X, Y, and Z. Therefore, the number of unknown variables is 9, the same as the number of magnetic field components acquired by the sensor. The relationship between the initial magnetic field matrix B0, the transformation matrix A, and the remanent magnetization matrix M0 of the ferromagnetic material is as follows:

[0073] B0=AM0

[0074] The size of the transformation matrix A is 9×9, that is, the transformation matrix A can be expressed as:

[0075]

[0076] To obtain the transformation matrix A, we need to take A 11 To A 99 These 81 values.

[0077] In COMSOL Multiphysics, the remanent magnetization of each domain is changed and the magnetic induction intensity values ​​of the data points are read. After obtaining 9 sets of remanent magnetization and magnetic induction intensity data, the remanent magnetization matrix M and the spatial magnetic induction matrix B are obtained, both of size 9×9. The remanent magnetization matrix M and the spatial magnetic induction matrix B satisfy the following relationship:

[0078] B=AM

[0079] Substitute the residual magnetization matrix M and the spatial magnetic induction matrix B, and use the MATLAB program to determine whether M is full rank. If not, continue to calculate the data in the finite element model until M is full rank, and then multiply M on both sides of the equal sign. -1 , we can get:

[0080] A=BM -1

[0081] The transformation matrix A is verified to be full rank by MATLAB. Substituting its expression into the expression for the residual magnetization matrix M0 of the ferromagnetic material, we can obtain:

[0082] M0=A -1 B0

[0083] The size of the residual magnetization matrix M0 of the ferromagnetic material is 9×1. Substituting the obtained residual magnetization into the constitutive relationship B=μ0(H+M) and ignoring the geomagnetic field, the 9 residual magnetization components of the material can be obtained, thereby obtaining the size and direction of the uniformly distributed residual magnetization of the 3-segment ferromagnetic material and displaying it on the host computer.

[0084] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A system for measuring the remanence of a ferromagnetic body, characterized in that: Including fluxgate sensor array, data integrator, and host computer; The fluxgate sensor array is used to measure the three components of the magnetic induction intensity X, Y, and Z at a specified spatial point and transmit them to the host computer through a data integrator; The host computer is used to receive magnetic field data from the fluxgate sensor array, obtain an initial magnetic field matrix B0 after processing, combine the conversion matrix A obtained by calculating the residual magnetization matrix M and the spatial magnetic induction intensity B, calculate the residual magnetization matrix M0 of the ferromagnetic material, and finally obtain the remanence of the material by combining the constitutive relationship; The host computer includes a data receiving module, a COMSOL Multiphysics finite element software module and a MATLAB calculation module; the data receiving module is used to receive the magnetic induction intensity measured by the fluxgate sensor array; the COMSOL Multiphysics finite element software module is used to establish a proportional finite element model, divide the corresponding domains according to actual conditions, wherein the number of domains is the number of uniform remanent magnetization segments n, and the size of the remanent magnetization intensity matrix M and the spatial magnetic induction intensity matrix B is determined by the number of domains n, and the full-rank remanent magnetization intensity matrix M and the corresponding spatial magnetic induction intensity matrix B are obtained by modifying the initial magnetization intensity in three directions of different domains; the MATLAB calculation module is used to combine the remanent magnetization intensity matrix M and the spatial magnetic induction intensity matrix B to calculate the full-rank conversion matrix A, combine the initial magnetic field matrix B0 and the conversion matrix A, calculate the remanent magnetization matrix M0 of the ferromagnetic material, and calculate the remanence of the material in combination with the constitutive relationship.

2. The measurement system according to claim 1, characterized in that The number of sensors in the fluxgate sensor array is equal to the number n of uniform residual magnetization segments.

3. A measuring method based on the ferromagnetic remanence measuring system according to claim 1 or 2, characterized in that: The following steps are involved: (1) Place the ferromagnetic object at the far end of the measurement point, and record the measured magnetic field matrix as B 01 , then place the ferromagnetic object near the measuring point, and record the measured magnetic field matrix as B 02 , then the initial magnetic field matrix generated by the ferromagnetic remanence is B0=B 02 -B 01 ; (2) Establish a proportional finite element model and divide the corresponding domains according to the actual situation. The number of domains is the number of uniform remanent magnetization segments n. The size of the remanent magnetization matrix M and the spatial magnetic induction matrix B is determined by the number of domains n. By modifying the initial magnetization in three directions of different domains, the full-rank remanent magnetization matrix M and the spatial magnetic induction matrix B are obtained. (3) Combining the residual magnetization matrix M and the spatial magnetic induction matrix B, the full-rank transformation matrix A is calculated; Combined with the initial magnetic field matrix B0 and the conversion matrix A, the residual magnetization matrix M0 of the ferromagnetic material is calculated, and combined with the constitutive relationship, the remanence of the material is calculated; The calculation formula of the residual magnetization matrix M0 of ferromagnetic materials is: M0=A -1 B0 The constitutive relationship is B=μ0(H+M), where H is the magnetic field intensity, M is the magnetization intensity, μ0 is the vacuum magnetic permeability, and B is the magnetic induction intensity.

4. The measuring method according to claim 3, characterized in that The residual magnetization matrix M must be full rank to ensure its reversibility. Therefore, if M is not full rank after calculation, data needs to be calculated again until M is full rank.

5. The measuring method according to claim 3, characterized in that For a ferromagnet that is usually placed in a fixed background magnetic field for a long time, the remanent magnetism of the ferromagnet is considered to be uniform, and n=1.

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