CN-122021538-A - Modularized reconfigurable active compensation system and planar coil segmentation design method based on flow function superposition and optimization

CN122021538ACN 122021538 ACN122021538 ACN 122021538ACN-122021538-A

Abstract

The invention provides a modularized reconfigurable active compensation system and a planar coil segmentation design method based on flow function superposition and optimization, relates to the field of electromagnetic compensation, and solves the problems of low space utilization rate, large weight, weak installation suitability, complex manual winding process and poor consistency caused by dependence on a whole plate substrate, small effective compensation area caused by insufficient consideration of magnetic shielding room boundary mirror image effect and insufficient magnetic field uniformity caused by the fact that a traditional integral flow function compensation coil is inseparable and has poor flexibility. According to the invention, through an algorithmic design flow, the integral flow function coil pattern which is difficult to divide conventionally is decomposed into a plurality of discrete sub-coil modules which can be independently manufactured and flexibly arranged and electrically connected, so that the goals of light system, high space utilization and reconfigurability are achieved while high-performance magnetic field compensation is realized.

Inventors

DAI XINPING
PAN DONGHUA
Lin Jiuge
CHEN YITAO
Jin Chongyu
LI LIYI

Assignees

哈尔滨工业大学

Dates

Publication Date: 20260512
Application Date: 20260205

Claims (10)

1. A modularized reconfigurable active compensation system is characterized by comprising a modularized coil assembly which is adapted to a magnetic shielding room and is formed by splicing a plurality of square sub-coil modules which are consistent in structural dimension and can be independently and electrically connected, The modularized coil assembly is a square sub-coil module formed by dividing a regularized grid, the dividing mode is 2n×2n or (2n+1) × (2n+1), n is more than or equal to 1, all the sub-coil modules are planar coils made of printed circuit boards, the modularized coil assembly is of a double-parallel planar coil structure, the two planar coils are symmetrically arranged on the upper inner side and the lower inner side of the magnetic shielding chamber, the sub-coil modules are prepared through a flexible circuit process, and are flexibly arranged and spliced according to the inner size of the magnetic shielding chamber.
2. The modular reconfigurable active compensation system of claim 1, wherein when the split mode is 2nx2n, the center of the sub-coil module in the upper right corner of the regularized grid is taken as the origin of the two-dimensional planar coordinate system; when the segmentation mode is (2n+1) × (2n+1), the center of the regularized grid is taken as the origin of the two-dimensional plane coordinate system.
3. The modular reconfigurable active compensation system of claim 2, wherein the sub-coil modules are assembled and fixed by a detachable electrical connection structure, the arranged and spliced modular coil assembly has no whole board substrate support, and the outer boundary dimension of the modular coil assembly is adapted to the inner space of the magnetic shielding chamber.
4. The modular reconfigurable active compensation system of claim 3, wherein the printed circuit board of the sub-coil module is a flexible substrate, the wires of the sub-coil module are printed conductive traces, and the wire routing of a single sub-coil module is a closed loop structure.
5. A planar coil segmentation design method based on flow function superposition and optimization, based on any one of claims 1-4, characterized by comprising the following steps: S1, carrying out regularized grid segmentation on a target plane coil region, wherein the segmentation mode is 2n×2n or (2n+1) × (2n+1), and n is more than or equal to 1; s2, establishing a corresponding two-dimensional plane coordinate system according to the segmentation mode, and determining current source point coordinates of the sub-coil module based on a mirror image method by combining boundary parameters of the magnetic shielding chamber; S3, pushing a magnetic field expression generated by the sub-coil module at a field point based on the Biaote-savart law; S4, setting target compensation magnetic field distribution, and enabling the combined magnetic fields of all the sub-coil modules to be consistent with the target compensation magnetic field through a flow function superposition optimization algorithm; S5, outputting the wire routing pattern of each sub-coil module.
6. The planar coil segmentation design method based on flow function superposition and optimization according to claim 5, wherein in S2, comprising the steps of: S21, boundary parameters of the magnetic shielding chamber comprise distances between the whole plane of the coil and the top wall, the bottom wall, the front wall, the rear wall, the left wall and the right wall of the magnetic shielding chamber, h 1 ,h 2 ,w 1 ,w 2 ,l 1 ,l 2 are respectively arranged, the distance between the coils of the double parallel planes is 2D, the half side length of each square sub-coil module is L, the mirror image effect of the boundary of the magnetic shielding chamber on a current source is considered according to a mirror image method in an electromagnetic field theory, and equivalent source point coordinates corresponding to current micro-elements in a calculation space in the nth sub-coil module are determined, wherein the x coordinates are determined according to the distribution positions of the sub-coil modules and are distributed as follows: x 11 =L+h 1 ,x 12 =(4n-1)L+h 2 , x 21 =3L+h 1 ,x 22 =(4n-3)L+h 2 , x 31 =5L+h 1 ,x 32 =(4n-5)L+h 2 , ... x n1 =(2n-1)L+h1,x n2 =(2n+1)L+h 2 , The y-coordinate and z-coordinate distribution is the following: y 11 =L+w 1 ,y 12 =(4n-1)L+w 2 , y 21 =3L+w 1 ,y 22 =(4n-3)L+w 2 , y 31 =5L+w 1 ,y 32 =(4n-5)L+w 2 , ... y n1 =(2n-1)L+w1,y n2 =(2n+1)L+w 2 , z 1 =D+l 1 ; z 2 =D+l 2 ; s22, obtaining field point coordinates on the coil under the mirror image method, wherein the field point coordinates are respectively as follows: wherein D is half of the distance between the coils in the double parallel planes, and i, j and k are mirror indexes.
7. The planar coil segmentation design method based on flow function superposition and optimization according to claim 6, wherein in S3, taking a B x shim coil as an example for initial flow function generation, the magnetic field generated by the coil field point is deduced by using the biot-savart law and expressed as follows: Wherein P nm is a coefficient to be solved, and n and m are harmonic order numbers; U mn =U 11 +U 12 +U 21 +U 22 +…+U num1 +U num2 , num is less than or equal to n, and the size of num is determined according to the distribution condition of the sub-coil modules.
8. The flow function superposition and optimization based planar coil segmentation design method according to claim 7, wherein expressions of U num1 and U num2 are respectively: Mu 1 and mu 2 are permalloy magnetic permeability and air magnetic permeability respectively, mu 0 is vacuum magnetic permeability, the coordinates of a target area, namely a field point are x, y and z, 、、 And Is the mirror lower field point coordinates.
9. The planar coil split design method based on flow function superposition and optimization according to claim 8, wherein in S4, target field setting is performed, an ideal magnetic field distribution b_target to be generated in the compensation region is clarified, and superposition and optimization of magnetic fields are performed according to the distribution of coils, so that the resultant magnetic field generated by all sub-coil modules at the field point is the same as the target magnetic field, i.e. b_target=b x .
10. The planar coil segmentation design method based on flow function superposition and optimization according to claim 9, wherein in S5, the wire routing pattern is composed of equal flow function wires, and is directly used for plate making of a printed circuit board.

Description

Modularized reconfigurable active compensation system and planar coil segmentation design method based on flow function superposition and optimization Technical Field The invention relates to the technical field of electromagnetic compensation, in particular to a modularized reconfigurable active compensation system and a planar coil segmentation design method based on flow function superposition and optimization. Background Magnetoencephalography (Magnetoencephalography, MEG) is a non-invasive neuroimaging technique that detects the magnetic field of electrically active neuronal populations in the human brain. Since the neuron-generated magnetic field amplitude is very small, the magnitude of the signal strength is on the order of tens to hundreds of femtoliters, which is one of the earth's magnetic fields 109, and is also several orders of magnitude smaller than other magnetic field environments. Therefore, a near-zero magnetic shielding room formed by high magnetic permeability materials is an essential experimental condition for measuring MEG, the shielding room is generally built by high magnetic permeability permalloy, and due to holes in the shielding room and reserved shielding doors, a certain residual magnetic field exists in the shielding room, often the residual magnetic field is different from tens to tens nT, the magnetic field in the shielding room changes along with time, and a certain difficulty is increased for measuring brain magnetic signals. In order to enable the self-free exchange relaxation (Spin-Exchange Relaxation Free, SERF) atomic magnetometer for measuring MEG to work with higher sensitivity, the magnetic field of the working environment needs to be less than a few nT, a coil is arranged in the SERF atomic magnetometer to compensate a certain magnetic field, however, the compensation cannot be changed in real time according to the magnetic field environment, once the SERF atomic magnetometer changes along with the head position of a tested person, vector projection generated by the change of the magnetic field can enable the sensor to exceed the dynamic working range, and the sensor cannot work in the linear working range, so that the sensor data cannot be used. The existing research adopts an active compensation mode to reduce the residual magnetic field in the shielding room, and the method reduces the cost and creates conditions for measuring the brain magnetic signals. However, the current compensation coil is often designed by adopting a flow function, the planar coil design of the compensation system obtained by the method usually depends on a whole plate (such as a wood plate or an acrylic plate) as a winding substrate, and a series of obvious defects exist in practical application, namely, firstly, the limitation of the structural design is prominent. The coil size is often severely limited by the size of the magnetic shield Room (MAGNETICALLY SHIELDED Room, MSR) door frame due to the reliance on a single integral plate structure, which is difficult to flexibly access during installation. This not only restricts the maximization of coil bore, also leads to MSR inner space not being fully utilized, especially the direction of height and corner area are often wasted, influence whole magnetic field compensation efficiency. The whole plate type planar coil is generally made of plates with larger thickness so as to ensure structural rigidity, and the manual winding process is complex, so that the whole weight of the coil is large, and the manufacturing cost is high. In addition, the processes of cutting the plate, positioning the winding and fixing the winding depend on manpower, consistency and precision are difficult to ensure, manufacturing cost and production period are further increased, and large-scale popularization and application of the compensation system are not facilitated. Furthermore, with the popularization of light and small MSR, the conventional large-sized planar coil is difficult to adapt to the limited internal space and compact layout thereof. The whole plate structure cannot flexibly adjust the shape and the size, is difficult to effectively deploy in various emerging application scenes, and limits the applicability of the whole plate structure in an advanced magnetic shielding environment. Therefore, the existing whole-plate planar coil based on the flow function design has obvious defects in space utilization, economy, light weight and adaptability, and a novel coil structure is needed to overcome the defects so as to promote wider application of the high-performance magnetic compensation system. Disclosure of Invention The invention provides a modularized reconfigurable active compensation system and a planar coil segmentation design method based on flow function superposition and optimization, which decompose a traditional integral flow function coil pattern which is difficult to segment into a plurality of discretized sub-coil modules which can be i