Design method of non-discrete shim coil and related device

Abstract

The invention discloses a design method of a non-discrete shim coil and a related device. The method comprises the following steps: determining a polar angle and a starting point radius of each track point of each layer of spiral line according to the number of track point sequences of each layer of spiral line and design parameters of a planar spiral coil, and calculating polar coordinates of each track point of the current layer of spiral line; according to the polar coordinates of the track points of all layers of spiral lines, splicing to obtain an initial planar spiral coil; generating another initial plane spiral coil in mirror symmetry with the same shape to form a double-plane shimming coil; carrying out electromagnetic simulation on the biplanar shim coil, and carrying out iterative optimization by using a preset optimization algorithm and taking the design parameters of the planar spiral coil as variables according to the difference between the magnetic field intensity data of a simulation magnetic field generated by the shim coil in a preset space and the magnetic field intensity data of a target magnetic field, and obtaining the non-discrete shim coil until a preset iteration stop condition is reached.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic field shimming, and in particular to a design method for a non-discrete shimming coil and a related device. Background Art

[0002] Highly uniform magnetic fields have important applications in many fields. For example, in quantum computing, the efficiency and stability of qubit operations and quantum information processing are highly dependent on highly uniform magnetic fields. Furthermore, in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI), highly uniform magnetic fields are crucial for producing accurate and clear images. Furthermore, highly uniform magnetic fields play a vital role in particle physics experiments, materials science research, and biology and chemistry.

[0003] Achieving a highly uniform magnetic field requires shimming technology to improve the nonuniformity of the main magnetic field and offset the effects of external magnetic fields. Shimming refers to the process of making the magnetic field distribution in space more uniform. Common shimming methods are divided into passive shimming and active shimming. Passive shimming is a coarse adjustment, while active shimming is a fine adjustment.

[0004] Passive shimming improves the uniformity of the magnetic field in the target area by adjusting the spatial angle of the magnet. The principle is to place magnetic material gaskets at various locations in the magnetic field space to improve the uniformity of the magnetic field. This method is very cumbersome and highly dependent on the operator's accumulated experience. Active shimming uses shim coils to generate additional compensation magnetic fields to compensate for the main magnetic field, thereby improving the uniformity of the magnetic field in the target area. The principle is to use the magnetic effect of current to generate a compensation magnetic field to offset the uneven components in the main magnetic field. This method is more flexible, easier to automate, and more accurate than passive shimming.

[0005] The cornerstone of active shimming technology is the design of efficient shim coils. The shape of the shim coils determines the spatial distribution and intensity of the compensation magnetic field. The main challenge in shim coil design is how to design the coil shape that generates the magnetic field.

[0006] The current mainstream design method for shim coils is the target field method. This method performs a spherical harmonic expansion on the target magnetic field value in the target area to obtain multiple orthogonal magnetic field components. Each shim coil corresponds to a magnetic field component, so that the magnetic field in the target spatial area can be made uniform by compensating for each component. Next, the Biot-Savart law is used to establish the relationship between the current density of the shim coil and the magnetic field it generates. The target field method is then used to inversely determine the planar current density distribution of the shim coil corresponding to each magnetic field component. Finally, the stream function is used to discretize the current density distribution according to the equal current criterion to obtain the current direction (i.e., coil shape) layout of the discrete shim coils. Summary of the Invention

[0007] In view of the above problems, the present invention is proposed to provide a design method and related devices for a non-discrete shim coil that overcomes the above problems or at least partially solves the above problems.

[0008] In a first aspect, an embodiment of the present invention provides a design method for a non-discrete shim coil, comprising:

[0009] Obtaining set design parameters of the planar spiral coil; the design parameters include the number of layers of the spiral coil, the maximum radius and the minimum radius of the spiral coil, the shape parameters of each layer of spirals, the starting angle and the ending angle of each layer of spirals, the normalized maximum spiral angle, and the spacing between adjacent spirals;

[0010] Determining the polar angle and starting point radius of each trajectory point of each spiral layer according to the number of trajectory point sequences of each spiral layer and the design parameters;

[0011] Calculating the polar coordinates of each trajectory point of the current layer helix according to the polar angle, starting point radius and shape parameters of each trajectory point of the current layer helix, and the normalized maximum helix angle;

[0012] According to the polar coordinates of each trajectory point of all layers of spiral lines, the initial planar spiral coil is spliced ​​together;

[0013] Generate another initial plane spiral coil with the same shape and mirror symmetry to form a double-plane shim coil;

[0014] Performing electromagnetic simulation on the dual-plane shim coil, and calculating magnetic field strength data of a simulated magnetic field generated by the shim coil in a preset space after the simulation is completed;

[0015] According to the difference between the magnetic field intensity data of the simulated magnetic field and the magnetic field intensity data of the target magnetic field, a preset optimization algorithm is used, with the design parameters of the planar spiral coil as variables, to perform iterative optimization until the preset iteration stop condition is reached, thereby obtaining a non-discrete shim coil.

[0016] In one embodiment, determining the polar angle and starting point radius of each trajectory point of each spiral layer according to the number of trajectory point sequences of each spiral layer and the design parameters includes:

[0017] Determine the polar angle of each trajectory point of each spiral layer according to the number of trajectory point sequences, the starting angle and the ending angle of each spiral layer;

[0018] The maximum radius of the spiral coil is used as the starting radius of the outermost spiral line, and for the non-outermost spiral line, based on the angle change relationship and spacing between the current layer spiral line and the previous layer spiral line, the starting radius of the current layer spiral line is calculated according to the normalized maximum spiral line angle, the shape parameters of the current layer spiral line, and the end point radius of the previous layer spiral line.

[0019] In one embodiment, for a non-outermost helix, based on the angle change relationship and spacing between the current helix and the previous helix, the starting radius of the current helix is ​​calculated according to the normalized maximum helix angle, the shape parameters of the current helix, and the end radius of the previous helix, including:

[0020] Determine whether the angle of the current layer's spiral is decreasing;

[0021] If so, if the angle of the previous layer of spirals also decreases, the starting point radius of the current layer of spirals is calculated based on the end point radius of the previous layer of spirals, the normalized maximum spiral angle, the polar angle and shape parameters of the starting point of the current layer of spirals; otherwise, the starting point radius of the current layer of spirals is calculated based on the end point radius of the previous layer of spirals, the normalized maximum spiral angle, the spacing between the current layer of spirals and the previous layer of spirals, the polar angle and shape parameters of the starting point of the current layer of spirals;

[0022] If not, if the angle of the previous layer of spiral increases, the starting point radius of the current layer of spiral is calculated based on the end point radius of the previous layer of spiral, the normalized maximum spiral angle, the polar angle and shape parameters of the starting point of the current layer of spiral; otherwise, the starting point radius of the current layer of spiral is calculated based on the end point radius of the previous layer of spiral, the normalized maximum spiral angle, the spacing between the current layer of spiral and the previous layer of spiral, the polar angle and shape parameters of the starting point of the current layer of spiral.

[0023] In one embodiment, the polar coordinates of each trajectory point of the current layer helix are calculated based on the polar angle, starting point radius and shape parameters of each trajectory point of the current layer helix, and the normalized maximum helix angle, including:

[0024] Calculating the radius of each trajectory point of the current layer helix according to the polar angle, starting point radius and shape parameters of each trajectory point of the current layer helix, and the normalized maximum helix angle;

[0025] According to the polar angle and radius of each track point of the current layer spiral line, the polar coordinates of each track point of the current layer spiral line are obtained.

[0026] In one embodiment, before splicing the initial planar spiral coil according to the polar coordinates of the trajectory points of all the spiral layers, the method further includes:

[0027] The trajectory points whose radius in all the spiral layers is smaller than the minimum radius of the spiral coil are filtered out.

[0028] In one embodiment, the step of splicing the initial planar spiral coil according to the polar coordinates of the trajectory points of all the spiral lines comprises:

[0029] Convert the polar coordinates of each trajectory point of all layers of the spiral into Cartesian coordinates;

[0030] The initial planar spiral coil is obtained by splicing the trajectory points of all the spiral layers according to the Cartesian coordinates of each trajectory point of all the spiral layers.

[0031] In one embodiment, the method of obtaining a non-discrete shim coil by iteratively optimizing the design parameters of the planar spiral coil as variables using a preset optimization algorithm based on the difference between the magnetic field strength data of the simulated magnetic field and the magnetic field strength data of the target magnetic field until a preset iterative stop condition is reached includes:

[0032] Calculating a value of a preset loss function based on the magnetic field strength data of the simulated magnetic field, wherein the loss function represents a difference between the magnetic field strength data of the simulated magnetic field and the magnetic field strength data of the target magnetic field;

[0033] Resetting the design parameters of the planar spiral coil using a preset optimization algorithm according to the value of the loss function;

[0034] Using the newly set design parameters, an optimized planar spiral coil is generated;

[0035] An optimized dual-plane shim coil is obtained according to the optimized planar spiral coil, an electromagnetic simulation is performed on the optimized dual-plane shim coil, and magnetic field strength data of the optimized dual-plane shim coil obtained after the simulation is completed in a preset space is calculated;

[0036] Repeat the above steps until the number of iterations reaches a preset upper limit or the value of the loss function converges;

[0037] The non-discrete shim coil is designed according to the value of the design parameter obtained when the iteration stops.

[0038] In one embodiment, performing electromagnetic simulation on the dual-plane shim coil and calculating magnetic field strength data of a simulated magnetic field generated by the shim coil in a preset space after the simulation is completed includes:

[0039] Performing electromagnetic simulations on the dual-plane shim coils under each error condition according to the set trace width, trace thickness, trace width error, and trace thickness error, and calculating magnetic field strength data of a simulated magnetic field generated by the shim coils in a preset space after each simulation is completed;

[0040] The calculating of the value of the preset loss function according to the magnetic field strength data of the simulated magnetic field includes:

[0041] The value of the preset loss function is calculated based on the magnetic field strength data of the simulated magnetic field under each error condition.

[0042] In a second aspect, an embodiment of the present invention provides a design device for a non-discrete shim coil, comprising:

[0043] an acquisition module for acquiring set design parameters of the planar spiral coil; the design parameters include the number of layers of the spiral coil, the maximum radius and the minimum radius of the spiral coil, the shape parameters of each layer of spirals, the starting angle and the ending angle of each layer of spirals, the normalized maximum spiral angle, and the spacing between adjacent spirals;

[0044] A first calculation module is used to determine the polar angle and starting point radius of each trajectory point of each spiral layer according to the number of trajectory point sequences of each spiral layer and the design parameters;

[0045] A second calculation module is used to calculate the polar coordinates of each trajectory point of the current layer helix according to the polar angle, starting point radius and shape parameters of each trajectory point of the current layer helix and the normalized maximum helix angle;

[0046] A splicing module is used to splice the initial planar spiral coil according to the polar coordinates of each trajectory point of all layers of spiral lines;

[0047] A shim coil module is used to generate another initial planar spiral coil with the same shape and mirror symmetry to form a dual-plane shim coil;

[0048] A simulation module is used to perform electromagnetic simulation on the dual-plane shim coil and calculate magnetic field strength data of a simulated magnetic field generated by the shim coil in a preset space after the simulation is completed;

[0049] The optimization module is used to perform iterative optimization based on the difference between the magnetic field intensity data of the simulated magnetic field and the magnetic field intensity data of the target magnetic field, using a preset optimization algorithm and the design parameters of the planar spiral coil as variables until a preset iteration stop condition is reached to obtain a non-discrete shim coil.

[0050] In a third aspect, an embodiment of the present invention provides a computing device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method for designing a non-discrete shim coil as described above is implemented.

[0051] In a fourth aspect, an embodiment of the present invention provides a computer program product, including a computer program / instruction, which implements the aforementioned method for designing a non-discrete shim coil when executed by a processor.

[0052] In a fifth aspect, an embodiment of the present invention provides a computer-readable storage medium storing a computer program, which implements the aforementioned method for designing a non-discrete shim coil when executed by a processor.

[0053] The beneficial effects of the above technical solutions provided by the embodiments of the present invention include at least:

[0054] The design method for a non-discrete shim coil provided in an embodiment of the present invention determines the polar angle and starting radius of each trajectory point of each spiral layer using the set design parameters of the planar spiral coil. This determines the polar coordinates of all trajectory points of each coil layer, and then splices the initial planar spiral coil to form a dual-plane shim coil. Modeling and electromagnetic simulation are then performed. The magnetic field intensity data of the dual-plane shim coil within a preset space after the simulation is completed is calculated, and the difference between the magnetic field intensity data and the target magnetic field intensity data is calculated. Using a preset optimization algorithm, the design parameters used as variables are iteratively optimized until the iteration stops, resulting in the planar spiral coil. The planar spiral coil can be directly designed into a continuous, conductive shape, eliminating the need for interconnecting discrete ring structures and significantly reducing layout and production difficulties. Furthermore, because the actual layout and production can be performed directly based on the obtained planar spiral coil that meets the target requirements, the shimming effect of the planar spiral coil after the actual layout is connected is consistent with the theoretical design effect during the simulation, avoiding the effect deviation caused by subsequent additional interconnection operations, and significantly improving the reliability of the shim coil after engineering.

[0055] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purposes and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0056] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0058] Figure 1 is a flow chart of a design method for a non-discrete shim coil in an embodiment of the present invention;

[0059] Figure 2 A schematic diagram of the layout of an initial planar spiral coil provided in an embodiment of the present invention;

[0060] Figure 3 This is a structural block diagram of a device for designing non-discrete shim coils provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0061] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0062] The inventor of the present application has found that although the prior art can obtain current routing that satisfies the target set by the shim coil, what it obtains is a theoretical structure, i.e., several independent and mutually separated annular structures, without connection between adjacent structures. In actual engineering use, it is impossible to supply power to each discrete annular structure separately, firstly because the complexity of the structure is increased, and secondly, it is difficult to satisfy the equal current size flowing through all the annular structures. Discrete shim coils cannot be used, and it is necessary to connect discrete coils in series to realize the conduction of current. However, it is found in the electromagnetic field simulation process that the different openings and connection modes between adjacent annular structures have a great impact on the performance of the shim coil. That is to say, the shimming effect of the discrete coils after the actual layout (layout) is turned on will be very different from the simulation design, and the actual effect deviates from the theoretical design effect, causing great inconvenience to the design of the shim coil.

[0063] Based on the above-mentioned problems existing in the prior art, the inventors of this application have proposed a new design method for non-discrete shim coils, which can directly design the shim coils into a continuous and conductive shape, eliminating the trouble of connecting discrete ring structures and avoiding the effect deviation caused by subsequent additional connection operations.

[0064] The inventors of this application proposed a design method for non-discrete shim coils, referring to Figure 1 As shown, the following steps are included:

[0065] S101: Obtaining set design parameters of the planar spiral coil; the design parameters include the number of layers of the spiral coil, the maximum radius and the minimum radius of the spiral coil, the shape parameters of each layer of spirals, the starting angle and the ending angle of each layer of spirals, the normalized maximum spiral angle, and the spacing between adjacent spirals;

[0066] S102: determining the polar angle and starting point radius of each trajectory point of each spiral layer according to the number of trajectory point sequences of each spiral layer and the design parameters;

[0067] S103: Calculating the polar coordinates of each trajectory point of the current layer helix according to the polar angle, starting point radius and shape parameters of each trajectory point of the current layer helix, and the normalized maximum helix angle;

[0068] S104: splicing the polar coordinates of the trajectory points of all the spiral lines to obtain an initial planar spiral coil;

[0069] S105: Generate another initial planar spiral coil with the same shape and mirror symmetry to form a dual-plane shim coil;

[0070] S106: performing electromagnetic simulation on the dual-plane shim coil, and calculating magnetic field strength data of a simulated magnetic field generated by the shim coil in a preset space after the simulation is completed;

[0071] S107: Based on the difference between the magnetic field strength data of the simulated magnetic field and the magnetic field strength data of the target magnetic field, a preset optimization algorithm is used, with the design parameters of the planar spiral coil as variables, to perform iterative optimization until a preset iteration stop condition is reached, thereby obtaining a non-discrete shim coil.

[0072] In the embodiment of the present invention, the set design parameters of the planar spiral coil obtained in the above step S101 can be a set of pre-set parameters to be optimized, wherein the initially set design parameters can be parameter values ​​designed by the designer based on the actual design objectives of the shim coil. The initially set design parameters include the number of layers N of the spiral coil, the maximum radius parameter R of the spiral coil, and the initial value of ... m And the minimum radius parameter R0, the shape parameters of each layer of spiral line p[p1,p2,…,p N ], the starting angle and ending angle of each layer of spiral [θ1,θ2,…,θ (N+1) ], normalized maximum helix angle θ max =max(θ i), the wiregap between adjacent spirals. Of course, the design parameters for the planar spiral coils in the embodiments of the present invention can also be determined based on the wiring layout implementation methods of other shim coils in the prior art, and no specific limitation is imposed on this. To facilitate subsequent modeling and simulation calculations, the initially set design parameters can also include the wire width and wire thickness of the planar spiral coils.

[0073] In an embodiment of the present invention, for two adjacent layers of spirals, the ending angle of the previous layer of spirals is the same as the starting angle of the current layer of spirals. Since the directions of the two adjacent layers of spirals can be the same or different, for two adjacent layers of spirals with the same direction, the directions of the two adjacent layers of spirals are both clockwise or counterclockwise, then the ending radius of the previous layer of spirals is the same as the starting radius of the current layer of spirals. In other words, the previous layer of spirals and the current layer of spirals are continuous and have no spacing. For two adjacent layers of spirals with different directions, one of the two adjacent layers of spirals is clockwise and the other is counterclockwise, then the difference between the ending radius of the previous layer of spirals and the starting radius of the current layer of spirals is equal to the spacing between the two adjacent layers of spirals.

[0074] In one embodiment, in the above step S102, determining the polar angle and starting radius of each trajectory point of each spiral layer according to the number of trajectory point sequences of each spiral layer and the design parameters specifically includes the following steps:

[0075] S1021: Determine the polar angle of each trajectory point of each spiral layer according to the number of trajectory point sequences, the starting angle, and the ending angle of each spiral layer;

[0076] S1022: The maximum radius of the spiral coil is used as the starting radius of the outermost spiral line, and for the non-outermost spiral line, based on the angle change relationship and spacing between the current layer spiral line and the previous layer spiral line, the starting radius of the current layer spiral line is calculated according to the normalized maximum spiral line angle, the shape parameters of the current layer spiral line, and the end point radius of the previous layer spiral line.

[0077] In one specific embodiment, the number n of trajectory point sequences for each spiral layer in step S1021 can be pre-set. A technician can determine the size of n based on actual design requirements. The larger n, the smoother the resulting spiral. In the embodiment of the present invention, the number of trajectory point sequences for each spiral layer is the same. The polar angles of each trajectory point in each spiral layer are calculated, thereby generating a polar angle sequence for each spiral layer. When generating the polar angle sequence for each spiral layer, each spiral layer can be processed separately from the outside to the inside. For each spiral, a linearly spaced numerical sequence is generated based on the starting and ending angles of the current spiral layer and the number of trajectory point sequences in the spiral layer in a descending order (i.e., a clockwise division). This sequence of linearly spaced values ​​is used to obtain the polar angles of each trajectory point in the current spiral layer. Since the polar angle sequence for each spiral is generated in a descending order, for a clockwise spiral, the starting angle is the polar angle ranked first among the generated polar angles of each trajectory point, i.e., the polar angle of the spiral's starting point. For a counterclockwise spiral, in the subsequent calculation process, the polar angles of all generated trajectory points need to be sorted in reverse order. The starting angle is then the polar angle ranked last among the polar angles of the generated trajectory points, i.e., the polar angle of the starting point of the spiral. In other words, in this embodiment of the present invention, for a spiral with decreasing angles (clockwise), the polar angle of the starting point of the spiral is the polar angle ranked first among the polar angles of the generated trajectory points. For a spiral with increasing angles (counterclockwise), the polar angle of the starting point of the spiral is the polar angle ranked last among the polar angles of the generated trajectory points.

[0078] In one embodiment, in the above step S1022 , the starting radius of the outermost spiral line is set to the maximum radius of the spiral coil in the set design parameters.

[0079] In one embodiment, in step S1022, for a non-outermost helix, the starting radius of the current helix is ​​calculated based on the angle change relationship and spacing between the current helix and the previous helix, the normalized maximum helix angle, the shape parameters of the current helix, and the end radius of the previous helix. This can be achieved in the following manner:

[0080] Determine whether the angle of the current layer's spiral is decreasing;

[0081] If so, if the angle of the previous layer of spirals also decreases, the starting point radius of the current layer of spirals is calculated based on the end point radius of the previous layer of spirals, the normalized maximum spiral angle, the polar angle and shape parameters of the starting point of the current layer of spirals; otherwise, the starting point radius of the current layer of spirals is calculated based on the end point radius of the previous layer of spirals, the normalized maximum spiral angle, the spacing between the current layer of spirals and the previous layer of spirals, the polar angle and shape parameters of the starting point of the current layer of spirals;

[0082] If not, if the angle of the previous layer of spiral increases, the starting point radius of the current layer of spiral is calculated based on the end point radius of the previous layer of spiral, the normalized maximum spiral angle, the polar angle and shape parameters of the starting point of the current layer of spiral; otherwise, the starting point radius of the current layer of spiral is calculated based on the end point radius of the previous layer of spiral, the normalized maximum spiral angle, the spacing between the current layer of spiral and the previous layer of spiral, the polar angle and shape parameters of the starting point of the current layer of spiral.

[0083] When processing a non-outermost spiral, that is, an inner spiral, first determine whether the angle of the current spiral is decreasing:

[0084] (1) If the angle of the current spiral layer decreases, then further determine whether the angle of the previous spiral layer also decreases:

[0085] If the angles of both the previous and current helices decrease, the starting radius of the current helices is calculated based on the following formula 1, according to the end radius of the previous helices, the normalized maximum helical angle, the polar angle of the starting point of the current helices, and the shape parameters:

[0086]

[0087] Among them, R i Indicates the starting radius of the i-th layer spiral, r (i+1)(end) Indicates the end point radius of the i+1th layer spiral, θ i(1) represents the polar angle of the starting point of the i-th layer spiral, p i represents the shape parameter of the i-th layer spiral, θ max represents the normalized maximum helix angle;

[0088] If the angle of the current helix decreases and the angle of the previous helix increases, the starting radius of the current helix is ​​calculated based on the following formula 2 according to the end radius of the previous helix, the normalized maximum helix angle, the spacing between the current helix and the previous helix, the polar angle of the starting point of the current helix, and the shape parameters:

[0089]

[0090] Among them, Ri Indicates the starting radius of the i-th layer spiral, r (i+1)(end) Indicates the end point radius of the i+1 layer spiral, wiregap i represents the distance between the i-th layer spiral and the i+1-th layer spiral, θ i(1) represents the polar angle of the starting point of the i-th layer spiral, p i represents the shape parameter of the i-th layer spiral, θ max represents the normalized maximum helix angle;

[0091] (2) If the angle of the current spiral increases, then further determine whether the angle of the previous spiral also increases:

[0092] If the angles of the current layer helix and the previous layer helix are both increasing, then the starting point radius of the current layer helix is ​​calculated based on the following formula 3 according to the end point radius of the previous layer helix, the normalized maximum helix angle, the polar angle of the starting point of the current layer helix, and the shape parameters;

[0093]

[0094] Among them, R i Indicates the starting radius of the i-th layer spiral, r (i+1)(end) Indicates the end point radius of the i+1th layer spiral, θ i(end) represents the polar angle of the starting point of the i-th layer spiral, p i represents the shape parameter of the i-th layer spiral, θ max represents the normalized maximum helix angle;

[0095] If the angle of the current helix increases while the angle of the previous helix decreases, the starting radius of the current helix is ​​calculated based on the following formula 4 according to the end radius of the previous helix, the normalized maximum helix angle, the spacing between the current helix and the previous helix, the polar angle of the starting point of the current helix, and the shape parameters:

[0096]

[0097] Among them, R i Indicates the starting radius of the i-th layer spiral, r (i+1)(end) Indicates the end point radius of the i+1 layer spiral, wiregap i represents the distance between the i-th layer spiral and the i+1-th layer spiral, θ i(end) represents the polar angle of the starting point of the i-th layer spiral, p i represents the shape parameter of the i-th layer spiral, θ max Represents the normalized maximum helix angle.

[0098] In one embodiment, after the starting radius of each helix layer is calculated according to step S102, the polar coordinates of each trajectory point of the helix layer in the current layer are calculated based on the polar angle, starting radius, and shape parameters of each trajectory point of the helix layer in the current layer, as well as the normalized maximum helix angle, as described in step S103. Specifically, the following steps are included:

[0099] S1031: Calculating the radius of each trajectory point of the current layer helix according to the polar angle, starting point radius and shape parameters of each trajectory point of the current layer helix, and the normalized maximum helix angle;

[0100] S1032: Obtain polar coordinates of each track point of the current layer of spiral line according to the polar angle and radius of each track point of the current layer of spiral line.

[0101] In a specific embodiment, the radius of each trajectory point of the current layer helix is ​​calculated in step S1031 based on the polar angle, starting radius and shape parameters of each trajectory point of the current layer helix, and the normalized maximum helix angle, and is specifically achieved by:

[0102] If the angle of the current helix decreases, the radius of each trajectory point of the current helix is ​​calculated based on the polar angle, starting point radius and shape parameters of each trajectory point of the current helix, as well as the normalized maximum helix angle, based on the following formula 5:

[0103]

[0104] Among them, r i Represents the radius of the trajectory point of the i-th layer spiral, R i Indicates the starting radius of the i-th layer spiral, θ i Represents the polar angle of the trajectory point of the i-th layer spiral, p i represents the shape parameter of the i-th layer spiral, θ max represents the normalized maximum helix angle;

[0105] If the angle of the current helix increases, the radius of each trajectory point of the current helix is ​​calculated based on the polar angle, starting radius and shape parameters of each trajectory point of the current helix, as well as the normalized maximum helix angle, based on the following formula 6:

[0106]

[0107] Among them, r i Represents the radius of the trajectory point of the i-th layer spiral, R i Indicates the starting radius of the i-th layer spiral, θ i Represents the polar angle of the trajectory point of the i-th layer spiral, pi represents the shape parameter of the i-th layer spiral, θ max represents the normalized maximum helix angle, and flip represents the flip sequence function.

[0108] In a specific embodiment, before executing the above step S104 to splice the initial planar spiral coil according to the polar coordinates of the trajectory points of all the spiral layers, the method may further include the following steps:

[0109] S103 ′: Filter out the trajectory points in all spiral layers whose radius is smaller than the minimum radius of the spiral coil.

[0110] In this way, redundant trajectory points in the inner region of the planar spiral coil are filtered out, so that a planar spiral coil that better meets the target requirements can be obtained during the subsequent spiral coil splicing.

[0111] In one embodiment, after filtering the trajectory points of all the spiral layers obtained in step S103 based on the above step S103′, the above step S104 splices the initial planar spiral coil according to the polar coordinates of the trajectory points of all the spiral layers, which specifically includes the following steps:

[0112] S1041: converting the polar coordinates of each trajectory point of all layers of the spiral into Cartesian coordinates;

[0113] S1042: According to the Cartesian coordinates of each trajectory point of all the spiral layers, the trajectory points of all the spiral layers are spliced ​​together to obtain the initial planar spiral coil.

[0114] In an embodiment of the present invention, in the above step S1041, the polar coordinates of each trajectory point of all layers of spiral lines are known, and the horizontal coordinate and vertical coordinate of the corresponding trajectory point in the Cartesian coordinate system can be calculated respectively according to the cosine function formula x=rcos(θ) and the sine function formula y=rsin(θ), so as to obtain the Cartesian coordinates of the corresponding trajectory point.

[0115] In the embodiment of the present invention, in the above step S1042, the Cartesian coordinates of each track point of all layers of spiral lines are known, and all track points can be connected in sequence from outside to inside to obtain the initial planar spiral coil.

[0116] In the embodiment of the present invention, in the above step S105, taking the construction of the Z shim coil as an example, assuming that the dual-plane shim coil is in the target spatial region and z=±a, then taking the xy plane in the target spatial region as the mirror plane, another initial planar spiral coil is generated with the same shape and mirror symmetry to form the dual-plane shim coil.

[0117] In one embodiment, in the above-mentioned step S106, the step of performing electromagnetic simulation on the dual-plane shim coil and calculating the magnetic field strength data of the simulated magnetic field generated by the shim coil in a preset space after the simulation is completed can be implemented in electromagnetic simulation software, and the electromagnetic simulation software can adopt the electromagnetic simulation software already available in the prior art.

[0118] The simulation process in step S106 is implemented by controlling the electromagnetic simulation software through programming software. Specifically, the following steps may be included:

[0119] Obtain the plane coordinate information of each point on the dual-plane shim coil, and build a shim coil model based on the set trace width and trace thickness;

[0120] According to the set simulation conditions, the shim coil model is simulated and calculated to obtain the theoretical magnetic field value at each position in the spatial magnetic field;

[0121] Within a set spatial area in the spatial magnetic field, the point coordinates of multiple positions and the corresponding theoretical magnetic field values ​​are obtained in a discrete point manner according to the set sampling interval, as the magnetic field intensity data in the preset space between the shim coils.

[0122] The following is Figure 2 The planar spiral coil shown in the figure is modeled and simulated, and the process of obtaining the simulation results is described in detail as an example:

[0123] First, according to Figure 2 The spiral planar coil is shown, and the Z-axis distance z=±a of the dual-plane shim coil is set, and the point coordinates of each position in the dual-plane shim coil are obtained.

[0124] Next, use the programming software to open the electromagnetic simulation software.

[0125] Next, the obtained point coordinates of each position in the dual-plane shim coil are imported into electromagnetic simulation software to reproduce the theoretical line shape of the dual-plane shim coil with no thickness and no width.

[0126] Next, the trace width and thickness of the conductor are added to the theoretical line shape to obtain a theoretical 3D model, completing the modeling. The trace width and thickness of the conductor can be set according to actual needs.

[0127] Next, set up the simulation conditions, including but not limited to: the simulation space size and space material (Background), the electromagnetic conditions of the space boundaries (Boundaries), the current size of the dual-plane shim coils (Current Ports), the mesh size (Mesh Type), and the solver settings (Setup Solver). Once the settings are complete, start the software to perform the simulation. After the calculation is complete, the theoretical magnetic field values ​​at all locations in the entire space are obtained.

[0128] Since theoretical magnetic field values ​​are generally not required for the entire space, a portion of the preset space can be selected from the simulation results as discrete points. For example, to facilitate obtaining theoretical magnetic field values, the selected space can be a circumscribed cube of the magnetic field center sphere, and the theoretical magnetic field values ​​of this preset space can be derived as the data source for verification. For example, sampling can be performed at a sampling interval of 0.6 mm, and theoretical magnetic field values ​​at multiple locations within the cube space with an X range of -3 to 3 mm, a Y range of -3 to 3 mm, and a Z range of -3 to 3 mm can be selected to obtain the magnetic field strength data of the dual-plane shim coil within the preset space.

[0129] In one embodiment, in step S107, based on the difference between the magnetic field intensity data of the simulated magnetic field and the magnetic field intensity data of the target magnetic field, a preset optimization algorithm is used, with the design parameters of the planar spiral coil as variables, to perform iterative optimization until a preset iterative stop condition is reached, thereby obtaining a non-discrete shim coil. Specifically, the following steps are included:

[0130] S1071: Calculating a value of a preset loss function based on the magnetic field strength data of the simulated magnetic field, where the loss function represents a difference between the magnetic field strength data of the simulated magnetic field and the magnetic field strength data of the target magnetic field;

[0131] S1072: Resetting the design parameters of the planar spiral coil using a preset optimization algorithm according to the value of the loss function;

[0132] S1073: Resetting the design parameters of the planar spiral coil using a preset optimization algorithm according to the value of the loss function;

[0133] S1074: Using the newly set design parameters, based on the above steps S102 to S106, an optimized planar spiral coil is generated;

[0134] S1075: Obtain an optimized dual-plane shim coil based on the optimized planar spiral coil, perform electromagnetic simulation on the optimized dual-plane shim coil, and calculate magnetic field strength data of the optimized dual-plane shim coil obtained after the simulation in a preset space;

[0135] S1076: Repeat steps S1071 to S1075 until the number of iterations reaches a preset upper limit or the value of the loss function converges;

[0136] S1077: Design the non-discrete shim coil according to the value of the design parameter obtained when the iteration stops.

[0137] In an embodiment of the present invention, when performing electromagnetic simulation on the dual-plane shim coil in step S106, the routing error is taken into account. Then, in step S106, performing electromagnetic simulation on the dual-plane shim coil and calculating magnetic field strength data of a simulated magnetic field generated by the shim coil in a preset space after the simulation is completed specifically includes:

[0138] Performing electromagnetic simulations on the dual-plane shim coils under each error condition according to the set trace width, trace thickness, trace width error, and trace thickness error, and calculating magnetic field strength data of a simulated magnetic field generated by the shim coils in a preset space after each simulation is completed;

[0139] Correspondingly, in the above step S1071, the value of the preset loss function is calculated according to the magnetic field strength data of the simulated magnetic field, specifically including:

[0140] The value of the preset loss function is calculated based on the magnetic field strength data of the simulated magnetic field under each error condition.

[0141] In the embodiment of the present invention, the above loss function can be selected according to the actual calculation target. For example, the residual between the magnetic field intensity data of the target magnetic field and the magnetic field intensity data of the simulated magnetic field can be used as the loss function.

[0142] If, in the above step S106, the routing error is not considered when performing electromagnetic simulation on the dual-plane shim coil, taking the dual-plane shim coil as a Z shim coil as an example, the electromagnetic simulation of the dual-plane shim coil is performed according to the set routing width width and routing thickness routing thickness, and the magnetic field strength data of the simulated magnetic field generated by the shim coil in the preset space after the simulation is completed is calculated. In the above step S1071, the residual of the magnetic field intensity data of the target magnetic field and the magnetic field intensity data of the simulated magnetic field is used as the loss function, that is, the magnetic field intensity data of the theoretical spatial distribution of each order magnetic field in the Z direction to be generated is converted into the loss function. Magnetic field strength data corresponding to the simulated magnetic field Make the residual and use it as the loss function The spatial coordinates (x, y, z) traverse the target's uniform field space area in the form of discrete points.

[0143] If, in the above step S106, the routing error is considered when performing electromagnetic simulation on the dual-plane shim coil, and the dual-plane shim coil is taken as a Z shim coil as an example, then according to the set routing width width, routing thickness thickness, routing width error Δw and routing thickness error Δt, electromagnetic simulation is performed on the dual-plane shim coil under each error condition, and the magnetic field strength data of the simulated magnetic field generated by the shim coil in the preset space after the simulation is completed is calculated. There are 9 simulation results of shim coils in total. In the above step S1071, the residual of the magnetic field strength data of the target magnetic field and the magnetic field strength data of the simulated magnetic field is used as the loss function, that is, the mean of the residual of the magnetic field strength data of the simulated magnetic field and the magnetic field strength data of the target magnetic field under each error condition is used as the loss function, that is, the loss function in, That is, it shows the simulation results of the above 9 shim coils.

[0144] In an embodiment of the present invention, in the subsequent iterative optimization process of the design parameters, the steps of constructing an optimized dual-plane shim coil for electromagnetic simulation based on the optimized design parameters, and calculating the magnetic field strength data of the shim coil in a preset space obtained after the simulation are also implemented in the above-mentioned electromagnetic simulation software, and the implementation method is similar to that in the above-mentioned step S106.

[0145] In the embodiment of the present invention, the preset optimization algorithm may be a single optimization algorithm, such as a genetic algorithm, or the preset optimization algorithm may be a combination of multiple optimization algorithms.

[0146] In the process of optimizing design parameters using multiple optimization algorithms, the execution order of the multiple optimization algorithms can be predetermined, and then the corresponding steps of the optimization are executed in sequence according to the preset order.

[0147] In one embodiment, the above-mentioned preset optimization algorithm may include, for example: at least one global optimization algorithm and at least one local optimization algorithm;

[0148] At least one global optimization algorithm and at least one local optimization algorithm are executed in sequence according to a preset order; the global optimization algorithm is executed earlier than the local optimization algorithm.

[0149] In one embodiment, the above-mentioned calculation process of splicing the initial planar spiral coil according to the set design parameters, performing data analysis on the calculated magnetic field strength data of the dual-plane shim coil, calculating the loss function, and iteratively optimizing the design parameters using the optimization algorithm can be implemented by some programming software modules through pre-compiled program codes, such as programming in the programming software to write various module codes such as design of non-discrete shim coils, iterative optimization, and control of electromagnetic simulation software simulation.

[0150] For example, taking the initial planar spiral coil obtained by splicing according to the set design parameters in the programming software as an example, it is assumed that the design parameters are the number of layers N of the spiral line, the shape parameters p[p1, p2, ..., p N ], the minimum radius parameter R0 of all helices, the maximum radius parameter R m 、The starting and ending angles of each layer of spiral [θ1,θ2,…,θ (N+1) ], normalized helix angle θ max =max(θ i ), the spacing wiregap between adjacent spirals. Furthermore, the spiral coil gradually generates spirals one by one from the outermost layer inward. The code for implementing the above steps S102 to S104 is expressed as follows:

[0151]

[0152]

[0153]

[0154] The design method for a non-discrete shim coil provided in an embodiment of the present invention determines the polar angle and starting radius of each trajectory point of each spiral layer using the set design parameters of the planar spiral coil. This determines the polar coordinates of all trajectory points of each coil layer, and then splices the initial planar spiral coil to form a dual-plane shim coil. Modeling and electromagnetic simulation are then performed. The magnetic field intensity data of the dual-plane shim coil within a preset space after the simulation is completed is calculated, and the difference between the magnetic field intensity data and the target magnetic field intensity data is calculated. Using a preset optimization algorithm, the design parameters used as variables are iteratively optimized until the iteration stops, resulting in the planar spiral coil. The planar spiral coil can be directly designed into a continuous, conductive shape, eliminating the need for interconnecting discrete ring structures and significantly reducing layout and production difficulties. Furthermore, because the actual layout and production can be performed directly based on the obtained planar spiral coil that meets the target requirements, the shimming effect of the planar spiral coil after the actual layout is connected is consistent with the theoretical design effect during the simulation, avoiding the effect deviation caused by subsequent additional interconnection operations, and significantly improving the reliability of the shim coil after engineering.

[0155] Based on the same inventive concept, an embodiment of the present invention further provides a design device for non-discrete shim coils. Since the principles of the problems solved by these devices are similar to those of the aforementioned design method for non-discrete shim coils, the implementation of the device can refer to the implementation of the aforementioned method, and the repeated parts will not be repeated.

[0156] An embodiment of the present invention provides a design device for a non-discrete shim coil, referring to Figure 3 Shown, including:

[0157] An acquisition module 101 is configured to acquire set design parameters of a planar spiral coil; the design parameters include the number of layers of the spiral coil, the maximum and minimum radii of the spiral coil, shape parameters of each spiral layer, the starting and ending angles of each spiral layer, a normalized maximum spiral angle, and the spacing between adjacent spirals;

[0158] A first calculation module 102 is configured to determine the polar angle and starting point radius of each trajectory point of each spiral layer according to the number of trajectory point sequences of each spiral layer and the design parameters;

[0159] A second calculation module 103 is configured to calculate the polar coordinates of each trajectory point of the current helix according to the polar angle, starting point radius and shape parameters of each trajectory point of the current helix, and the normalized maximum helix angle;

[0160] A splicing module 104 is used to splice the initial planar spiral coil according to the polar coordinates of each trajectory point of all layers of spiral lines;

[0161] The shim coil module 105 is used to generate another initial planar spiral coil with the same shape and mirror symmetry to form a dual-plane shim coil;

[0162] A simulation module 106 is configured to perform electromagnetic simulation on the dual-plane shim coil and calculate magnetic field strength data of a simulated magnetic field generated by the shim coil in a preset space after the simulation is completed;

[0163] The optimization module 107 is used to use a preset optimization algorithm to perform iterative optimization based on the difference between the magnetic field strength data of the simulated magnetic field and the magnetic field strength data of the target magnetic field, using the design parameters of the planar spiral coil as variables, until a preset iterative stop condition is reached, thereby obtaining a non-discrete shim coil.

[0164] In one embodiment, the present invention further provides a computing device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the aforementioned method for designing non-discrete shim coils when executing the program.

[0165] In one embodiment, the present invention further provides a computer program product, including a computer program / instruction, wherein the computer program / instruction implements the aforementioned method for designing non-discrete shim coils when executed by a processor.

[0166] In one embodiment, the present invention further provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the method for designing a non-discrete shim coil as described above is implemented.

[0167] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage and optical storage, etc.) containing computer-usable program code.

[0168] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0169] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0170] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0171] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A design method for a non-discrete shim coil, characterized in that: include: Obtaining set design parameters of the planar spiral coil; the design parameters include the number of layers of the spiral coil, the maximum radius and the minimum radius of the spiral coil, the shape parameters of each layer of spirals, the starting angle and the ending angle of each layer of spirals, the normalized maximum spiral angle, and the spacing between adjacent spirals; Determining the polar angle and starting point radius of each trajectory point of each spiral layer according to the number of trajectory point sequences of each spiral layer and the design parameters; Calculating the polar coordinates of each trajectory point of the current layer helix according to the polar angle, starting point radius and shape parameters of each trajectory point of the current layer helix, and the normalized maximum helix angle; According to the polar coordinates of each trajectory point of all layers of spiral lines, the initial planar spiral coil is spliced ​​together; Generate another initial plane spiral coil with the same shape and mirror symmetry to form a double-plane shim coil; Performing electromagnetic simulation on the dual-plane shim coil, and calculating magnetic field strength data of a simulated magnetic field generated by the shim coil in a preset space after the simulation is completed; According to the difference between the magnetic field intensity data of the simulated magnetic field and the magnetic field intensity data of the target magnetic field, a preset optimization algorithm is used, with the design parameters of the planar spiral coil as variables, to perform iterative optimization until the preset iteration stop condition is reached, thereby obtaining a non-discrete shim coil.

2. The method according to claim 1, wherein The step of determining the polar angle and starting point radius of each trajectory point of each spiral layer according to the number of trajectory point sequences of each spiral layer and the design parameters includes: Determine the polar angle of each trajectory point of each spiral layer according to the number of trajectory point sequences, the starting angle and the ending angle of each spiral layer; The maximum radius of the spiral coil is used as the starting radius of the outermost spiral line, and for the non-outermost spiral line, based on the angle change relationship and spacing between the current layer spiral line and the previous layer spiral line, the starting radius of the current layer spiral line is calculated according to the normalized maximum spiral line angle, the shape parameters of the current layer spiral line, and the end point radius of the previous layer spiral line.

3. The method according to claim 2, wherein For a non-outermost helix, based on the angle change relationship and spacing between the current helix and the previous helix, the normalized maximum helix angle, the shape parameters of the current helix, and the end point radius of the previous helix, the starting point radius of the current helix is ​​calculated, including: Determine whether the angle of the current layer's spiral is decreasing; If so, if the angle of the previous layer of spirals also decreases, the starting point radius of the current layer of spirals is calculated based on the end point radius of the previous layer of spirals, the normalized maximum spiral angle, the polar angle and shape parameters of the starting point of the current layer of spirals; otherwise, the starting point radius of the current layer of spirals is calculated based on the end point radius of the previous layer of spirals, the normalized maximum spiral angle, the spacing between the current layer of spirals and the previous layer of spirals, the polar angle and shape parameters of the starting point of the current layer of spirals; If not, if the angle of the previous layer of spiral increases, the starting point radius of the current layer of spiral is calculated based on the end point radius of the previous layer of spiral, the normalized maximum spiral angle, the polar angle and shape parameters of the starting point of the current layer of spiral; otherwise, the starting point radius of the current layer of spiral is calculated based on the end point radius of the previous layer of spiral, the normalized maximum spiral angle, the spacing between the current layer of spiral and the previous layer of spiral, the polar angle and shape parameters of the starting point of the current layer of spiral.

4. The method according to any one of claims 1 to 3, wherein The polar coordinates of each trajectory point of the current layer helix are calculated based on the polar angle, starting point radius and shape parameters of each trajectory point of the current layer helix, and the normalized maximum helix angle, including: Calculating the radius of each trajectory point of the current layer helix according to the polar angle, starting point radius and shape parameters of each trajectory point of the current layer helix, and the normalized maximum helix angle; According to the polar angle and radius of each track point of the current layer spiral line, the polar coordinates of each track point of the current layer spiral line are obtained.

5. The method according to claim 4, wherein Before the initial planar spiral coil is obtained by splicing the polar coordinates of the trajectory points of all the spiral lines, the following steps are also included: The trajectory points whose radius in all the spiral layers is smaller than the minimum radius of the spiral coil are filtered out.

6. The method according to claim 5, wherein The initial planar spiral coil is obtained by splicing the polar coordinates of the trajectory points of all the spiral lines, including: Convert the polar coordinates of each trajectory point of all layers of the spiral into Cartesian coordinates; The initial planar spiral coil is obtained by splicing the trajectory points of all the spiral layers according to the Cartesian coordinates of each trajectory point of all the spiral layers.

7. The method according to claim 1, wherein The method comprises: using a preset optimization algorithm based on the difference between the magnetic field strength data of the simulated magnetic field and the magnetic field strength data of the target magnetic field, and using the design parameters of the planar spiral coil as variables to perform iterative optimization until a preset iterative stop condition is reached to obtain a non-discrete shimming coil, including: Calculating a value of a preset loss function based on the magnetic field strength data of the simulated magnetic field, wherein the loss function represents a difference between the magnetic field strength data of the simulated magnetic field and the magnetic field strength data of the target magnetic field; Resetting the design parameters of the planar spiral coil using a preset optimization algorithm according to the value of the loss function; Using the newly set design parameters, an optimized planar spiral coil is generated; An optimized dual-plane shim coil is obtained according to the optimized planar spiral coil, an electromagnetic simulation is performed on the optimized dual-plane shim coil, and magnetic field strength data of the optimized dual-plane shim coil obtained after the simulation is completed in a preset space is calculated; Repeat the above steps until the number of iterations reaches a preset upper limit or the value of the loss function converges; The non-discrete shim coil is designed according to the value of the design parameter obtained when the iteration stops.

8. The method according to claim 7, wherein The performing electromagnetic simulation on the dual-plane shim coil and calculating magnetic field strength data of a simulated magnetic field generated by the shim coil in a preset space after the simulation is completed includes: Performing electromagnetic simulations on the dual-plane shim coils under each error condition according to the set trace width, trace thickness, trace width error, and trace thickness error, and calculating magnetic field strength data of a simulated magnetic field generated by the shim coils in a preset space after each simulation is completed; The calculating of the value of the preset loss function according to the magnetic field strength data of the simulated magnetic field includes: The value of the preset loss function is calculated based on the magnetic field strength data of the simulated magnetic field under each error condition.

9. A design device for non-discrete shim coils, characterized in that: include: an acquisition module for acquiring set design parameters of the planar spiral coil; the design parameters include the number of layers of the spiral coil, the maximum radius and the minimum radius of the spiral coil, the shape parameters of each layer of spirals, the starting angle and the ending angle of each layer of spirals, the normalized maximum spiral angle, and the spacing between adjacent spirals; A first calculation module is used to determine the polar angle and starting point radius of each trajectory point of each spiral layer according to the number of trajectory point sequences of each spiral layer and the design parameters; A second calculation module is used to calculate the polar coordinates of each trajectory point of the current layer helix according to the polar angle, starting point radius and shape parameters of each trajectory point of the current layer helix and the normalized maximum helix angle; A splicing module is used to splice the initial planar spiral coil according to the polar coordinates of each trajectory point of all layers of spiral lines; A shim coil module is used to generate another initial planar spiral coil with the same shape and mirror symmetry to form a dual-plane shim coil; A simulation module is used to perform electromagnetic simulation on the dual-plane shim coil and calculate magnetic field strength data of a simulated magnetic field generated by the shim coil in a preset space after the simulation is completed; The optimization module is used to perform iterative optimization based on the difference between the magnetic field intensity data of the simulated magnetic field and the magnetic field intensity data of the target magnetic field, using a preset optimization algorithm and the design parameters of the planar spiral coil as variables until a preset iteration stop condition is reached to obtain a non-discrete shim coil.

10. A computing device, characterized in that include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method for designing a non-discrete shim coil according to any one of claims 1 to 8 when executing the program.

11. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instruction is executed by a processor, the method for designing a non-discrete shim coil according to any one of claims 1 to 8 is implemented.

12. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for designing a non-discrete shim coil according to any one of claims 1 to 8 is implemented.

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