CN-122021289-A - Method and device for optimizing uniformity of central magnetic field of annular segmented iron yoke

CN122021289ACN 122021289 ACN122021289 ACN 122021289ACN-122021289-A

Abstract

The application provides a method and a device for optimizing the uniformity of a central magnetic field of an annular segmented iron yoke, relates to the technical field of superconducting electrical iron yokes, and solves the technical problem that the uniformity of the central magnetic field of a superconducting magnet is difficult to improve in the prior art. The method comprises the steps of obtaining physical basic parameters of a superconducting magnet, establishing a two-dimensional axisymmetric calculation model, determining radial and axial calculation ranges, generating a two-dimensional grid coordinate matrix, calculating an initial static magnetic field by utilizing the two-dimensional grid coordinate matrix based on the Biaose-Saval law and axisymmetric characteristics, constructing an annular iron yoke multiparameter optimization problem, carrying out global parameter search by adopting a genetic algorithm to obtain iron yoke optimization parameters, establishing a correction model of an iron yoke on a magnetic field by combining the magnetic dipole theory and ferromagnetic material saturation characteristics based on the iron yoke optimization parameters, calculating an additional magnetic field generated by the iron yoke, and superposing the additional magnetic field and the initial static magnetic field to obtain the total magnetic field intensity. The application is used for optimizing the uniformity of the central magnetic field of the iron yoke.

Inventors

Weng Yike
DING PING
ZHANG LIAN
XU HUI
Liao Jinyao
Ge Chuangwei
ZHU RONGTIAN
WANG DONGHU

Assignees

合肥曦合超导科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260126

Claims (10)

1. The method for optimizing the uniformity of the central magnetic field of the annular segmented iron yoke is characterized by comprising the following steps of: Obtaining physical basic parameters of the superconducting magnet, wherein the physical basic parameters comprise geometric parameters, electromagnetic parameters, material parameters and iron yoke constraints; establishing a two-dimensional axisymmetric calculation model based on the physical basic parameters, determining radial and axial calculation ranges of the coverage coil, the iron yoke and the magnetic field attenuation region, and generating a two-dimensional grid coordinate matrix; Calculating an initial static magnetic field generated by the superconducting coil in space by utilizing the two-dimensional grid coordinate matrix based on the Biaor-savart law and the axisymmetric characteristic; Constructing a ring-shaped yoke multi-parameter optimization problem, and carrying out global parameter search by adopting a genetic algorithm to obtain yoke optimization parameters; Based on a magnetic dipole theory and the saturation characteristic of ferromagnetic materials, a correction model of the magnetic field of the iron yoke is established by combining the iron yoke optimization parameters, an additional magnetic field generated by the iron yoke is calculated, and the additional magnetic field is overlapped with the initial static magnetic field to obtain the total magnetic field intensity.
2. The method of claim 1, wherein the geometric parameters include an inner diameter, an outer diameter, a height of the coil, the electromagnetic parameters include current density and vacuum permeability, the material parameters include electrical pure iron saturation induction, relative permeability, and material density, and the yoke constraints include a single-sided yoke number, a yoke maximum width, a yoke maximum depth, and a yoke coil gap range.
3. The method of claim 1, wherein after establishing a correction model of the magnetic field by the yoke based on the magnetic dipole theory and the saturation characteristics of the ferromagnetic material in combination with the yoke optimization parameters, calculating an additional magnetic field generated by the yoke, and superimposing the additional magnetic field with the initial static magnetic field to obtain a total magnetic field distribution, the method further comprises: calculating a uniformity improvement ratio based on the unevenness of the initial static magnetic field and the unevenness of the total magnetic field; verifying whether the position distribution and the distance between the iron yokes and the coil meet the preset constraint requirements.
4. The method of claim 2, wherein establishing a two-dimensional axisymmetric calculation model based on the physical base parameters, determining radial and axial calculation ranges of the coverage coil, the iron yoke, and the magnetic field attenuation region, and generating a two-dimensional grid coordinate matrix, comprises: determining radial and axial calculation boundaries of a coverage coil, an iron yoke and a magnetic field attenuation region based on the geometric parameters and the iron yoke constraint; Setting radial grid points and axial grid points, and calculating grid intervals; And generating coordinates of each grid point based on the grid spacing, and constructing a two-dimensional grid coordinate matrix.
5. The method of claim 2, wherein the calculating an initial static magnetic field generated in space by the superconducting coil using the two-dimensional grid coordinate matrix based on the biot-savart law and the axisymmetric characteristic comprises: calculating the magnetic field distribution on the shaft by adopting an analytic method based on the inner diameter and outer diameter contributions of the coil; The method comprises the steps of calculating an off-axis magnetic field approximately through an exponential decay model, wherein the exponential decay model characterizes the axial decay and radial growth saturation characteristics of the magnetic field through an axial decay function and a radial growth function; Introducing an end effect correction factor to correct magnetic field deviation at the end of the coil; And calculating an average magnetic field in a central area based on the two-dimensional grid coordinate matrix to obtain the initial static magnetic field.
6. The method of claim 2, wherein constructing the ring yoke multiparameter optimization problem, performing global parameter search using genetic algorithm to obtain yoke optimization parameters, comprises: Setting the position, width, depth and gap of each iron yoke as optimization variables; Constructing an objective function containing magnetic field non-uniformity, maximum relative deviation, central field change rate and constraint violation penalty; Setting the sequence constraint, the interval constraint and the boundary constraint of the iron yoke; And configuring population size, maximum algebra, crossover probability, mutation probability and convergence tolerance of a genetic algorithm, and performing global search through the genetic algorithm to output iron yoke optimization parameters.
7. The method of claim 2, wherein the establishing a correction model of the magnetic field by the yoke based on the magnetic dipole theory and the saturation characteristics of the ferromagnetic material in combination with the yoke optimization parameters, calculating an additional magnetic field generated by the yoke, and superimposing the additional magnetic field with the initial static magnetic field to obtain a total magnetic field strength comprises: calculating effective magnetization and volume of the iron yoke based on the iron yoke optimization parameters; Calculating the magnetic moment of an iron yoke based on the effective magnetization and the volume, and obtaining an additional magnetic field by combining a magnetic dipole theory; and introducing a geometric attenuation factor, and superposing the additional magnetic field of each iron yoke and the initial static magnetic field to obtain the total magnetic field intensity.
8. The method of claim 7, wherein calculating the magnetic moment of the iron yoke based on the effective magnetization and volume, in combination with magnetic dipole theory, obtains an additional magnetic field, comprising: Calculating the space distance between the coordinate of the observation point and the center coordinate of the iron yoke; Calculating a direction cosine according to the axial difference value and the radial difference value of the observation point and the center of the iron yoke and the space distance; Based on the magnetic moment, the spatial distance, and the directional cosine, an additional magnetic field at an observation point is calculated.
9. The method of claim 8, wherein calculating an additional magnetic field at an observation point based on the magnetic moment, the spatial distance, and the directional cosine satisfies the following formula: Wherein, the For the purpose of the additional magnetic field, For the vacuum permeability, m is the magnetic moment, For the direction cosine, dist is the spatial distance.
10. The device for optimizing the uniformity of the central magnetic field of the annular segmented yoke is characterized by comprising a communication unit and a processing unit; The communication unit is used for acquiring physical basic parameters of the superconducting magnet, wherein the physical basic parameters comprise geometric parameters, electromagnetic parameters, material parameters and iron yoke constraints; The processing unit is used for establishing a two-dimensional axisymmetric calculation model based on the physical basic parameters, determining radial and axial calculation ranges of a covered coil, an iron yoke and a magnetic field attenuation region, generating a two-dimensional grid coordinate matrix, calculating an initial static magnetic field generated by a superconducting coil in space by utilizing the two-dimensional grid coordinate matrix based on the Biaor-Saval law and axisymmetric characteristics, establishing an annular iron yoke multiparameter optimization problem, carrying out global parameter search by adopting a genetic algorithm to obtain iron yoke optimization parameters, establishing a correction model of the iron yoke on a magnetic field by combining the iron yoke optimization parameters based on a magnetic dipole theory and ferromagnetic material saturation characteristics, calculating an additional magnetic field generated by the iron yoke, and superposing the additional magnetic field and the initial static magnetic field to obtain total magnetic field intensity.

Description

Method and device for optimizing uniformity of central magnetic field of annular segmented iron yoke Technical Field The application relates to the technical field of superconducting electrical yokes, in particular to a method and a device for optimizing the uniformity of a central magnetic field of an annular segmented yoke. Background The improvement of the magnetic field uniformity of the central region of the superconducting magnet is a key for guaranteeing the reliable application of the superconducting magnet in the fields of precise measurement, medical imaging and the like, in the prior art, a symmetrically distributed fixed boss structure is mostly adopted to improve the magnetic field uniformity, specifically, bosses with fixed positions and sizes are designed in advance, the bosses are arranged based on symmetry principles, the magnetic field distribution is verified by means of finite element analysis, and boss parameters are manually adjusted to achieve the target magnetic field uniformity, but the method relies on manual experience or local parameter scanning, the design period is long, global optimal solution is difficult to find, the magnetic coupling effect between the bosses and the stability of the central magnetic field are not fully considered, and parameters such as the positions, the sizes and gaps of the bosses are independently adjusted, so that a systematic collaborative optimization model is lacked, and the technical problem that the uniformity of the central magnetic field of the superconducting magnet is difficult to improve exists in the prior art. Disclosure of Invention The application provides a method and a device for optimizing the uniformity of a central magnetic field of an annular segmented iron yoke, which solve the technical problem that the uniformity of the central magnetic field of a superconducting magnet is difficult to improve in the prior art. In order to achieve the above purpose, the application adopts the following technical scheme: The method comprises the steps of obtaining physical basic parameters of a superconducting magnet, wherein the physical basic parameters comprise geometric parameters, electromagnetic parameters, material parameters and iron yoke constraints, establishing a two-dimensional axisymmetric calculation model based on the physical basic parameters, determining radial and axial calculation ranges of a covered coil, an iron yoke and a magnetic field attenuation region to generate a two-dimensional grid coordinate matrix, calculating an initial static magnetic field generated by the superconducting coil in space by using the two-dimensional grid coordinate matrix based on the Piaor-Saval law and axisymmetric characteristics, constructing a ring-shaped iron yoke multiparameter optimization problem, performing global parameter search by using a genetic algorithm to obtain iron yoke optimization parameters, establishing a correction model of an iron yoke to a magnetic field based on a magnetic dipole theory and ferromagnetic material saturation characteristics in combination with the iron yoke optimization parameters, calculating an additional magnetic field generated by the iron yoke, and superposing the additional magnetic field and the initial static magnetic field to obtain total magnetic field intensity. Based on the technical scheme, in the annular segmented yoke central magnetic field uniformity optimization method provided by the application, through multi-parameter collaborative optimization and genetic algorithm global search, the global optimal improvement of the central magnetic field uniformity can be effectively realized by combining ferromagnetic material saturation characteristic modeling and central field stability control, and meanwhile, the magnetic field stability is ensured. With reference to the first aspect, in one possible implementation manner, the geometric parameters include an inner diameter, an outer diameter and a height of the coil, the electromagnetic parameters include current density and vacuum magnetic permeability, the material parameters include electrical pure iron saturation magnetic induction intensity, relative magnetic permeability and material density, and the iron yoke constraint includes a single-side iron yoke number, an iron yoke maximum width, an iron yoke maximum depth and an iron yoke coil gap range. With reference to the first aspect, in one possible implementation manner, after establishing a correction model of the magnetic field by the iron yoke based on the magnetic dipole theory and the saturation characteristic of the ferromagnetic material and combining the iron yoke optimization parameters, calculating an additional magnetic field generated by the iron yoke, and overlapping the additional magnetic field with the initial static magnetic field to obtain the total magnetic field distribution, the method further includes calculating a uniformity improvement rate based on the non-uniformi