Method and apparatus for designing a low leakage excitation coil for generating a high uniform magnetic field

Abstract

The application provides a low magnetic leakage excitation coil design method and device capable of generating a high uniform magnetic field, and belongs to the technical field of magnetic field control. The method comprises the following steps: determining a target magnetic induction intensity and a target uniform region length; based on a pre-constructed two-dimensional distribution function of the uniform region length and the central magnetic field intensity, the size parameters of the low magnetic leakage excitation coil corresponding to the target magnetic induction intensity and the target uniform region length are determined by using an interpolation method or a table lookup method; based on the size parameters and the condition that the magnetic moment of the low magnetic leakage excitation coil is zero, the ratio of the inner and outer turns of the low magnetic leakage excitation coil is determined; and based on the required target magnetic induction intensity and the target uniform region length, the designed low magnetic leakage excitation coil is in a low magnetic leakage state to the outside of the system, the magnetic interference on the surrounding equipment is reduced, and the measurement accuracy is effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of magnetic field control technology, and in particular to a method and device for designing a low-leakage magnetic excitation coil capable of generating a highly uniform magnetic field. Background Art

[0002] As magnetic field sensors develop increasingly towards high-precision and advanced technology, they are widely used in magnetic target detection, geomagnetic navigation, attitude measurement, ballistic magnetic correction, ship demagnetization and other fields. At the same time, they also play a huge role in space science, geophysics, resource exploration, environmental protection, biomedicine, aviation and navigation, composition detection and other fields closely related to national economic activities. The research on various ultra-high performance magnetic sensors based on different physical mechanisms is currently the most popular research direction in magnetic testing technology.

[0003] The generation of artificially controllable magnetic fields generally requires coils. For reproducing extremely weak magnetic fields, due to the presence of the Earth's magnetic field and environmental interference fields, active and passive shielding are currently used to establish the required magnetic field conditions using coils. The most common method is to directly use coils to reproduce the magnetic field within the shielding device. When combining ordinary coils with shielding systems, the high magnetic permeability of the shielding layer alters the magnetic field lines of the ordinary magnetic field coil, often leading to a series of problems such as changes in coil constants, changes in the magnetic field uniformity zone, magnetic field nonlinearity, and magnetization of the shielding tube. With the surge in spacecraft missions, magnetic field measurements have placed stringent requirements on time, space, accuracy, equipment, and instrumentation, and the aforementioned methods are no longer able to meet these requirements.

[0004] Therefore, how to design a low-leakage magnetic excitation coil that can generate a highly uniform magnetic field to meet the needs of high-precision magnetic measurement and control of spacecraft has become a technical problem that technicians in this field urgently need to solve. Summary of the Invention

[0005] The present invention provides a method and device for designing a low-leakage magnetic excitation coil that can generate a highly uniform magnetic field, so as to solve the defect in the prior art that coils cannot meet the requirements of high-precision magnetic measurement and control of spacecraft.

[0006] In a first aspect, the present invention provides a method for designing a low-leakage magnetic field coil capable of generating a highly uniform magnetic field, comprising:

[0007] Determine the target magnetic induction intensity and the target uniform area length;

[0008] Based on a pre-constructed two-dimensional distribution function of the uniform zone length and the central magnetic field intensity, the dimension parameters of the low leakage magnetic excitation coil corresponding to the target magnetic induction intensity and the target uniform zone length are determined by using an interpolation method or a table lookup method;

[0009] determine a ratio of inner and outer turns of the low leakage flux excitation coil based on the size parameter and a condition that a magnetic moment of the low leakage flux excitation coil is zero;

[0010] The low leakage flux excitation coil comprises a first group 1, 2 and a second group 3, 4, and the condition that the magnetic moment is zero is:

[0011] N 34 = k r N 12 ;

[0012]

[0013] wherein N 12 and N 34 are the number of turns of the first group of coils 1, 2 and the second group of coils 3, 4, respectively, r 12 and r 34 are the radii of the first group of coils 1, 2 and the second group of coils 3, 4, respectively; d 12 and d 34 are the thicknesses of the first group of coils 1, 2 and the second group of coils 3, 4, respectively; the radial integral variable h is the height of the coil inner diameter to the integration point along the radial direction; d 12 and d 34 are equal to the number of coil winding layers multiplied by the diameter of the enameled wire.

[0014] The design method of the low leakage flux excitation coil capable of generating a high uniform magnetic field provided by the application further comprises, before the determination of the target magnetic induction intensity and the target uniform zone length:

[0015] determining a first functional relationship between the low leakage flux excitation coil constant and the number of turns, the size and the position of the coil based on a steady-state magnetic induction intensity formula;

[0016] determining a second functional relationship between the uniformity length and the number of turns, the size and the position of the coil based on the uniformity length;

[0017] constructing a two-dimensional distribution function of the uniform zone length and the central magnetic field intensity based on the first functional relationship and the second functional relationship.

[0018] The design method of the low leakage flux excitation coil capable of generating a high uniform magnetic field provided by the application, wherein the constructing of the two-dimensional distribution function of the uniform zone length and the central magnetic field intensity based on the first functional relationship and the second functional relationship comprises:

[0019] determining the constraint conditions that the magnetic moment is zero and the center is symmetrical, respectively;

[0020] constructing the two-dimensional distribution function of the uniform zone length and the central magnetic field intensity based on the constraint conditions, the first functional relationship and the second functional relationship.

[0021] According to a method for designing a low-leakage magnetic excitation coil capable of generating a highly uniform magnetic field provided by the present invention, the constraint condition for the magnetic moment to be zero is:

[0022] N1r1 2 +N2 2 r2 2 =N3 2 r3 2 +N4 2 r4 2 ;

[0023] The central symmetry constraint is:

[0024] r1=r2; r3=r4; N1=N2; N3=N4;

[0025] x1=-x2=-r1 / 2; x3=-x4=-r3 / 2;

[0026] Where r1 and r2 represent the radius of the coils of the first group 1 and 2 respectively, r3 and r4 represent the radius of the coils of the second group 3 and 4 respectively, N1 and N2 represent the number of turns of the coils of the first group 1 and 2 respectively, N3 and N4 represent the number of turns of the coils of the second group 3 and 4 respectively, x1 and x2 represent the positions of the coils of the first group 1 and 2 on the x-axis respectively, and x3 and x4 represent the positions of the coils of the second group 3 and 4 on the x-axis respectively.

[0027] According to a method for designing a low-leakage magnetic excitation coil capable of generating a highly uniform magnetic field, the method comprises: constructing a two-dimensional distribution function of uniform region length and central magnetic field intensity based on the constraint conditions and in combination with the first functional relationship and the second functional relationship, including:

[0028] Based on the constraint conditions, combining the first functional relationship and the second functional relationship, a coil constant constraint function and a uniform region length constraint function are obtained;

[0029] Based on the preset number of turns, the coil constant constraint function and the uniform region length constraint function are optimized to obtain a two-dimensional distribution function of the uniform region length and the central magnetic field intensity.

[0030] According to a design method for a low-leakage magnetic excitation coil capable of generating a highly uniform magnetic field provided by the present invention, the coil constant constraint function is:

[0031] K B =f1(N 12 , N 34 , r 12 , r 34 );

[0032] The uniform region length constraint function is:

[0033] X L =f2(N 12 , N 34 , r 12 , r 34 );

[0034] Among them, K B Indicates the low leakage magnetic field coil constant, X L represents the length of the uniform area; r 12 and r 34 are the radii of the coils numbered 1 and 2 in the first group and 3 and 4 in the second group respectively; 12 and N 34 are the numbers of turns of the first group 1, 2 and the second group 3, 4 coils respectively, f1 represents the first functional relationship, and f2 represents the second functional relationship.

[0035] According to a design method for a low-leakage magnetic excitation coil capable of generating a highly uniform magnetic field provided by the present invention, the two-dimensional distribution function of the uniform zone length and the central magnetic field intensity is:

[0036] (K B , X L )=f12(r 12 , r 34 );

[0037] (r 12 , r 34 )=f12 -1 (K B , X L );

[0038] Among them, f12 -1 It is the inverse function of f12.

[0039] According to a design method for a low-leakage magnetic excitation coil capable of generating a highly uniform magnetic field provided by the present invention, the formula for the steady-state magnetic induction intensity is:

[0040] B=Σ i＝1 4 Σ j＝1 NiL [μ0I / 2(N i / N iL L i )][(x i +L i / 2-x) / (R ij 2 +(x i +L i / 2-x) 2 ) 3 / 2 +

[0041] (-x i +Li / 2+x) / (R ij 2 +(-x i +L i / 2+x) 2 ) 3 / 2 ];

[0042] Where μ0 is the vacuum permeability, xi is the x-axis coordinate of point i on the axis, x1, x2, x3, x4 are the x-axis positions of the first coil 1, 2 and the second coil 3, 4 respectively, r1, r2, r3, r4 are the radii of the first coil 1, 2 and the second coil 3, 4 respectively, R ij is the radius of the jth layer of the ith coil, N iL is the total number of layers of the i-th coil, N i is the number of turns of the i-th coil, I represents the current, L i represents the spacing of the i-th coil.

[0043] In a second aspect, the present invention provides a low-leakage magnetic field coil design device capable of generating a highly uniform magnetic field, comprising:

[0044] A first determination module is used to determine the target magnetic induction intensity and the target uniform area length;

[0045] A second determination module is configured to determine, based on a pre-constructed two-dimensional distribution function of the uniform zone length and the central magnetic field intensity, the size parameters of the low leakage magnetic excitation coil corresponding to the target magnetic induction intensity and the target uniform zone length by using an interpolation method or a table lookup method;

[0046] a third determining module, configured to determine a ratio of inner and outer turns of the low-leakage magnetic excitation coil based on the size parameter and a condition that the magnetic moment of the low-leakage magnetic excitation coil is zero;

[0047] The low leakage magnetic excitation coils include a first group 1, 2 and a second group 3, 4, and the condition for the magnetic moment to be zero is:

[0048] N 34 =k r N 12 ;

[0049]

[0050] Among them, N 12 and N 34 The number of turns of the first coil 1, 2 and the second coil 3, 4, respectively, r 12 and r 34 are the radii of the first set of coils 1 and 2 and the second set of coils 3 and 4 respectively; d 12 and d 34The thicknesses of the first set of coils 1, 2 and the second set of coils 3, 4, respectively; the radial integration variable h is the height of the coil inner diameter to the integration point along the radial direction; d 12 and d 34 is equal to the number of coil winding layers multiplied by the diameter of the enameled wire.

[0051] In a third aspect, the present application also provides an electronic device, comprising 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 low-leakage magnetic excitation coil capable of generating a high-uniform magnetic field according to any one of the above aspects when executing the program.

[0052] In a fourth aspect, the present application also provides a non-transitory computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the method for designing a low-leakage magnetic excitation coil capable of generating a high-uniform magnetic field according to any one of the above aspects.

[0053] In a fifth aspect, the present application also provides a computer program product comprising a computer program, wherein the computer program, when executed by a processor, implements the method for designing a low-leakage magnetic excitation coil capable of generating a high-uniform magnetic field according to any one of the above aspects.

[0054] The method and device for designing a low-leakage magnetic excitation coil capable of generating a high-uniform magnetic field provided by the present application comprise determining a target magnetic induction intensity and a target uniform zone length; based on a pre-constructed two-dimensional distribution function of the uniform zone length and the central magnetic field intensity, the size parameters of the low-leakage magnetic excitation coil corresponding to the target magnetic induction intensity and the target uniform zone length are determined by using an interpolation method or a table lookup method; based on the size parameters and the condition that the magnetic moment of the low-leakage magnetic excitation coil is zero, the ratio of the inner and outer turns of the low-leakage magnetic excitation coil is determined; based on the required target magnetic induction intensity and target uniform zone length, the designed low-leakage magnetic excitation coil has a low-leakage state to the outside, reduces the magnetic interference on the surrounding equipment, and effectively improves the measurement accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0055] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0056] Figure 1 is a flowchart of the method for designing a low-leakage magnetic excitation coil capable of generating a high-uniform magnetic field provided by the present embodiment;

[0057] Figure 2 is a schematic diagram of the assembly structure of the low-leakage magnetic excitation coil provided by the present embodiment;

[0058] Figure 3 Schematic diagram of the structure of a low-leakage magnetic excitation coil design device capable of generating a highly uniform magnetic field provided in this embodiment;

[0059] Figure 4 It is a structural diagram of the electronic device provided in this embodiment. DETAILED DESCRIPTION

[0060] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0061] Figure 1 FIG. 1 is a flow chart of a method for designing a low-leakage magnetic excitation coil capable of generating a highly uniform magnetic field, provided in this embodiment. Figure 2 Schematic diagram of the assembly structure of the low-leakage magnetic excitation coil provided in this embodiment.

[0062] like Figure 1 As shown, the embodiment of the present invention provides a method for designing a low-leakage magnetic excitation coil that can generate a highly uniform magnetic field. The method mainly includes the following steps:

[0063] 101. Determine the target magnetic induction intensity and the length of the target uniform area.

[0064] In a specific implementation, the low-leakage magnetic excitation coil consists of two sets of coaxial coils, one inside and one outside. The low-leakage magnetic excitation coils come in various forms, with each set of coils being a single coil (solenoid), a double coil (Helmholtz coil), or a quad coil (Wedrich coil). The two sets of coils are connected in series, with the currents reversed. By adjusting the parameters of the two sets of coils (size, number of turns, and relative position), the total magnetic moment of the low-leakage magnetic excitation coil is zero, and the magnetic induction intensity within the coil's working area is the difference between the magnetic induction intensities generated by the two sets of coils. This significantly reduces magnetic leakage while ensuring a certain excitation area. Therefore, the low-leakage magnetic excitation coil is defined as a low-leakage magnetic excitation coil.

[0065] When designing a low leakage magnetic excitation coil, two important indicators must be considered, namely the uniformity of the working area and the magnetic induction intensity of the working area. The quantitative indicator is the uniform area length X that meets a certain uniformity. L The maximum magnetic induction intensity B in normal operation at the center of the uniform area maxDue to space limitations, optimized low-magnetic leakage excitation coil design parameters are required to meet design specifications while also saving cost and space. Therefore, the two key indicators in this embodiment are the target magnetic induction intensity and the target uniform zone length. Due to the variety of low-magnetic leakage excitation coils, this embodiment uses a Helmholtz coil as an example to design low-magnetic leakage excitation coil parameters.

[0066] The target magnetic induction intensity and the target uniform zone length are the required magnetic induction intensity and the required uniform zone length, thereby ensuring that the designed low leakage magnetic excitation coil can meet the requirements for the magnetic induction intensity and the uniform zone length.

[0067] 102. Based on the pre-constructed two-dimensional distribution function of the uniform zone length and the central magnetic field intensity, the interpolation method or the table lookup method is used to determine the size parameters of the low leakage magnetic excitation coil corresponding to the target magnetic induction intensity and the target uniform zone length.

[0068] The design of low leakage magnetic field coil parameters is realized in two steps. The first step is to design the size of the low leakage magnetic field coil, and the second step is to design the number of turns of the low leakage magnetic field coil. Figure 2 The figure shows the assembly diagram of the low leakage magnetic excitation coil. C1 and C2 are the first group of coils 1 and 2, and C3 and C4 are the second group of coils 3 and 4. The radial dimensions of each pair of coils C1:C2 and C3:C4 are the same, and each pair is centrally symmetrical.

[0069] The design index of low leakage magnetic excitation coil (K) can be known through the pre-constructed two-dimensional distribution function of uniform area length and central magnetic field intensity. B , X L ) and low leakage magnetic field coil (r 12 , r 34 ) are mapped to each other with respect to the function f12, one to one correspondence. Given a set (r 12 , r 34 ) value can be solved to obtain a set of coil indexes (K B , X L ); Give N uniformly and discretely within a certain range x *N y Coil radius parameter (r 12 , r 34 ), we can get N x *N y Coil index (K B , X L ). Below is (B0, X L ) as the coil index, where B0 = K B I0, I0 is the unit current intensity, and (K B , X L ) are completely equivalent.

[0070] Solve the radius r of the two sets of coils inside and outside the low leakage magnetic excitation coil respectively 12 With r 34 With the coil uniform area length X L The two-dimensional distribution function of the central magnetic field intensity B0 is used to calculate a set of low leakage excitation coil design parameters (K B , X L ) to find the corresponding low leakage excitation coil size parameters, that is, the radius of the inner and outer coils (r 12 , r 34 ).

[0071] 103. Based on the size parameters and the condition that the magnetic moment of the low leakage magnetic excitation coil is zero, determine the ratio of the inner and outer turns of the low leakage magnetic excitation coil.

[0072] The magnetic moment of the low leakage excitation coil is zero, and the condition N is satisfied. 12 r 12 2 =N 34 r 34 2 , we can calculate the ratio of the number of turns of the inner and outer coils. Since the size effect of the coils is not taken into account, in fact, each set of coils has a certain thickness and length. Especially when the wire diameter is thick and the number of turns is large, the size effect of the coils cannot be ignored. Therefore, the condition of zero magnetic moment is adopted as shown in formula (1):

[0073]

[0074] Among them, N 12 and N 34 The number of turns of the first coil 1, 2 and the second coil 3, 4, respectively, r 12 and r 34 are the radii of the first set of coils 1 and 2 and the second set of coils 3 and 4 respectively; d 12 and d 34 are the thicknesses of the first set of coils 1 and 2 and the second set of coils 3 and 4 respectively; the radial integral variable h is the height from the inner diameter of the coil to the integration point along the radial direction; d 12 and d 34 Equal to the number of coil winding layers multiplied by the diameter of the enameled wire. Φ d The number of turns of the low leakage magnetic excitation coil should be kept as even as possible to eliminate the magnetic moment deviation caused by the helical current.

[0075] Calculate the uniform length X of the low leakage excitation coil L The central magnetic field strength B0 changes with the radius r of the inner and outer coils. 12 With r 34 The two-dimensional distribution function satisfies the condition of zero magnetic moment, as shown in formulas (2) and (3):

[0076] N34 =k r N 12 (2)

[0077]

[0078] The number of coil turns N is obtained using formula (2) 34 It is not an integer or an even number, so it needs to be rounded up or evened and then r 12 and r 34 Make corrections. 34 Take smaller value, k r Too small; when N 34 Taking a larger value, kr tends to be larger. Considering the distribution of design indicators with the inner and outer diameters of the coil, the coil parameters corresponding to point B are generally taken.

[0079] For example, given a set of low leakage magnetic field coil design indicators: X L =12cm, B0=2Gs, through the calculation of the above embodiment, the parameter r can be obtained 12 =29cm, r 34 =40cm.

[0080] Furthermore, based on the above embodiment, this embodiment also includes constructing a two-dimensional distribution function of the uniform area length and the central magnetic field intensity, as follows:

[0081] One of the design indicators of low leakage magnetic excitation coils, the calculation formula for the steady-state magnetic induction intensity generated by the coil is as follows:

[0082] B=K B I (4)

[0083] B is the magnetic induction intensity generated by the coil, in Tesla (T); K B is the low leakage magnetic field coil constant, in Tesla per ampere (T / A); I is the current flowing through the coil, in amperes (A). B is the number of coil turns N i0 、Size r i and position x i The first functional relationship f1, where i=1,2,3,4.

[0084] K B =f1(N i0 , r i , x i )(5)

[0085] The second design index of low leakage magnetic excitation coil is the uniform area length X L , meeting the uniformity requirement (e.g. 0.3%). L is the number of coil turns N i0、Size r i and position x i The second functional relationship f2, where i = 1, 2, 3, 4.

[0086] X L =f2(N i0 , r i , x i ) (6)

[0087] Finally, based on the first functional relationship and the second functional relationship, a two-dimensional distribution function of the uniform area length and the central magnetic field intensity is constructed.

[0088] Among them, the constraint condition for the total magnetic moment of the low leakage magnetic excitation coil to be zero requires:

[0089] N1r1 2 +N2 2 r2 2 =N3 2 r3 2 +N4 2 r4 2 (7)

[0090] The low leakage magnetic excitation coil meets the requirements of central symmetry and the structure meets the following relationships:

[0091] r1=r2; r3=r4; N1=N2; N3=N4(8)

[0092] x1=-x2=-r1 / 2; x3=-x4=-r3 / 2(9)

[0093] For the low leakage magnetic excitation coil composed of two pairs of Helmholtz coils, considering the constraints of symmetry and zero total magnetic moment, the coil constant K B and uniform zone length X L It can be simplified into the following constraint function:

[0094] K B =f1(N 12 , N 34 , r 12 , r 34 ) (10)

[0095] X L =f2(N 12 , N 34 , r 12 , r 34 ) (11)

[0096] N 12 r 12 2 =N 34 r 342 (12)

[0097] Among them, r1 and r2 represent the radius of the coils of the first group 1 and 2 respectively, r3 and r4 represent the radius of the coils of the second group 3 and 4 respectively, N1 and N2 represent the number of turns of the coils of the first group 1 and 2 respectively, N3 and N4 represent the number of turns of the coils of the second group 3 and 4 respectively, x1 and x2 represent the positions of the coils of the first group 1 and 2 on the x-axis respectively, x3 and x4 represent the positions of the coils of the second group 3 and 4 on the x-axis respectively, and the x-axis can be Figure 2 The dotted line shown, the center symmetry point of the first group 1, 2 coils and the second group 3, 4 coils is the coordinate origin. B Indicates the low leakage magnetic field coil constant, X L represents the length of the uniform area; r 12 and r 34 are the radii of the coils numbered 1 and 2 in the first group and 3 and 4 in the second group respectively; 12 and N 34 are the numbers of turns of the first group 1, 2 and the second group 3, 4 coils respectively, f1 represents the first functional relationship, and f2 represents the second functional relationship.

[0098] Given a design indicator X L , K B , the size r of each coil in the low leakage excitation coil can be optimized and calculated i , position x i and the number of coil turns N i0 For example, setting N 12 = 100 turns, then adjust the coefficient k and take the integer operation, and finally, the coil constant K B and uniform zone length X L It can be simplified to the following function:

[0099] (K B , X L )=f12(r 12 , r 34 ) (13)

[0100] (r 12 , r 34 )=f12 -1 (K B , X L ) (14)

[0101] It can be seen that the design index (K B , X L ) and the size of the low leakage magnetic field coil (r 12 , r 34 ) are mapped to each other with respect to the function f12, and the two-dimensional distribution function of the uniform region length and the central magnetic field intensity is obtained. -1is the inverse function of f12, so given a set (r 12 , r 34 ) value, a set of coil indexes (K B , X L ).

[0102] Use function f12 to calculate the design index of low leakage excitation coil (K B , X L ). Given a set of parameters r 12 , r 34 , N 12 , N 34 and current I0, solve the magnetic field intensity B0 at the center of the low leakage magnetic excitation coil, and get K B =B0 / I0; calculate the magnetic field intensity distribution B along the center axis of the low leakage magnetic excitation coil i , the uniform area length X of the low leakage magnetic excitation coil L Is to satisfy the magnetic field uniformity ε i The length of the interval is less than 0.3%. The expression of magnetic field uniformity is:

[0103] ε i =(B0-B i ) / B0(15)

[0104] Based on the above embodiment, in this embodiment, it is assumed that the current flowing through the circular coil with a radius r is I, and the magnetic induction intensity at point P on its axis at a distance x from the center of the circle is:

[0105] B=μ0Ir 2 / 2(r 2 +x 2 ) 3 / 2 (16)

[0106] Considering the coil as an ideal current loop and ignoring the size of the enameled wire, the magnetic field generated by the low-leakage magnetic excitation coil at a certain position P on the central axis is the superposition of the magnetic induction intensities generated by the four circular coils:

[0107] B=μ0 / 2[Ir1 2 / (r1 2 +(x i -x1) 2 ) 3 / 2 +

[0108] Ir2 2 / (r2 2 +(x i -x2) 2 ) 3 / 2 +Ir3 2 / (r3 2 +(x i -x3) 2) 3 / 2 +Ir4 2 / (r4 2 +(x i -x4) 2 ) 3 / 2 ](17)

[0109] Each coil is composed of a spiral coil wound on a circular ring. Assuming the wire is thin and the turns are tightly wound, each turn can be considered a circular coil. According to the principle of magnetic field superposition, the magnetic field at a point on the axis of a low-leakage magnetic excitation coil is the sum of the magnetic fields generated by the currents in each turn. The formula for the magnetic field generated by a single-coil, single-layer solenoid at point i on the axis is as follows:

[0110] B=Σ i＝1 4 Σ j＝1 NiL [μ0I / 2(N i / N iL L i )][(x i +L i / 2-x) / (R ij 2 +(x i +L i / 2-x) 2 ) 3 / 2 +

[0111] (-x i +L i / 2+x) / (R ij 2 +(-x i +L i / 2+x) 2 ) 3 / 2 ](18);

[0112] Where μ0 is the vacuum permeability, xi is the x-axis coordinate of point i on the axis, x1, x2, x3, x4 are the x-axis positions of the first coil 1, 2 and the second coil 3, 4 respectively, r1, r2, r3, r4 are the radii of the first coil 1, 2 and the second coil 3, 4 respectively, R ij is the radius of the jth layer of the ith coil, N iL is the total number of layers of the i-th coil, N i is the number of turns of the i-th coil, I represents the current, L i represents the spacing of the i-th coil.

[0113] First, the number of layers of a single coil is summed, and then the number of coils is summed to obtain the total magnetic field intensity at point i. In practice, the analytical form of function f12 is solved numerically in the space outside the centerline of the low-leakage excitation coil.

[0114] By adopting the design method of a low-leakage magnetic excitation coil that can generate a highly uniform magnetic field of the present invention, the magnetic induction intensity at any point in the low-leakage magnetic excitation system can be calculated, and then the magnetic field distribution of the entire coil system can be obtained. The magnetic field distribution law can be found to obtain a magnetic field area that meets the design requirements. The coil system is in a low-leakage magnetic state to the outside, reducing magnetic interference to surrounding equipment and effectively improving measurement accuracy. The coil system has a simple structure and high excitation efficiency, and can achieve high-precision magnetic field measurement and control in a limited space. The coil magnetic field intensity is controllable, and the magnetic field uniformity area is controllable, and can be adjusted and adapted according to different test requirements. The magnetic induction intensity at a certain position of the coil system achieves extremely low leakage magnetic field of the coil system, minimizing interference to surrounding equipment.

[0115] Based on the same general inventive concept, the present invention also protects a low leakage magnetic excitation coil design device that can generate a high uniform magnetic field. The low leakage magnetic excitation coil design device that can generate a high uniform magnetic field described below and the low leakage magnetic excitation coil design method that can generate a high uniform magnetic field described above can refer to each other.

[0116] Figure 3 Schematic diagram of the structure of the low leakage magnetic field coil design device that can generate a highly uniform magnetic field provided by this embodiment.

[0117] like Figure 3 As shown, this embodiment provides a low-leakage magnetic field coil design device that can generate a highly uniform magnetic field, including:

[0118] A first determination module 301 is used to determine a target magnetic induction intensity and a target uniform area length;

[0119] The second determination module 302 is configured to determine the size parameters of the low leakage magnetic field excitation coil corresponding to the target magnetic induction intensity and the target uniform area length by using an interpolation method or a table lookup method based on a pre-constructed two-dimensional distribution function of the uniform area length and the central magnetic field intensity;

[0120] A third determining module 303 is configured to determine a ratio of inner and outer turns of the low-leakage magnetic excitation coil based on the size parameter and the condition that the magnetic moment of the low-leakage magnetic excitation coil is zero;

[0121] The low leakage magnetic excitation coils include the first group 1, 2 and the second group 3, 4. The condition for the magnetic moment to be zero is:

[0122] N 34 =k r N 12 ;

[0123]

[0124] Among them, N 12 and N 34The number of turns of the first coil 1, 2 and the second coil 3, 4, respectively, r 12 and r 34 are the radii of the first set of coils 1 and 2 and the second set of coils 3 and 4 respectively; d 12 and d 34 are the thicknesses of the first set of coils 1 and 2 and the second set of coils 3 and 4 respectively; the radial integral variable h is the height from the inner diameter of the coil to the integration point along the radial direction; d 12 and d 34 It is equal to the number of coil winding layers multiplied by the diameter of the enameled wire.

[0125] Figure 4 It is a structural diagram of the electronic device provided in this embodiment.

[0126] like Figure 4 As shown, the electronic device may include: a processor 410, a communications interface 420, a memory 430, and a communications bus 440, wherein the processor 410, the communications interface 420, and the memory 430 communicate with each other via the communications bus 440. The processor 410 may call logic instructions in the memory 430 to execute a method for designing a low-leakage magnetic excitation coil capable of generating a highly uniform magnetic field. The method includes: determining a target magnetic induction intensity and a target uniform zone length; determining, based on a pre-constructed two-dimensional distribution function of the uniform zone length and the central magnetic field intensity, the size parameters of the low-leakage magnetic excitation coil corresponding to the target magnetic induction intensity and the target uniform zone length by using an interpolation method or a table lookup method; and determining, based on the size parameters and the condition that the magnetic moment of the low-leakage magnetic excitation coil is zero, the ratio of the number of inner and outer turns of the low-leakage magnetic excitation coil.

[0127] In addition, the logic instructions in the above-mentioned memory 430 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0128] On the other hand, the present invention also provides a computer program product, which includes a computer program, which can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the low leakage magnetic excitation coil design method that can generate a high uniform magnetic field provided by the above methods. The method includes: determining the target magnetic induction intensity and the target uniform zone length; based on a pre-constructed two-dimensional distribution function of the uniform zone length and the central magnetic field intensity, using an interpolation method or a table lookup method, determining the size parameters of the low leakage magnetic excitation coil corresponding to the target magnetic induction intensity and the target uniform zone length; based on the size parameters and the condition that the magnetic moment of the low leakage magnetic excitation coil is zero, determining the ratio of the inner and outer turns of the low leakage magnetic excitation coil.

[0129] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to execute the low leakage magnetic excitation coil design method for generating a high uniform magnetic field provided by the above-mentioned methods, the method comprising: determining the target magnetic induction intensity and the target uniform zone length; based on a pre-constructed two-dimensional distribution function of the uniform zone length and the central magnetic field intensity, using an interpolation method or a table lookup method, determining the size parameters of the low leakage magnetic excitation coil corresponding to the target magnetic induction intensity and the target uniform zone length; based on the size parameters and the condition that the magnetic moment of the low leakage magnetic excitation coil is zero, determining the ratio of the inner and outer turns of the low leakage magnetic excitation coil.

[0130] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0131] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, or of course, by hardware. Based on this understanding, the essence of the above technical solution or the part that contributes to the existing technology can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or certain parts of the embodiments.

[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for designing a low-leakage magnetic field coil capable of generating a highly uniform magnetic field, characterized in that: include: Determine the target magnetic induction intensity and the target uniform area length; Based on a pre-constructed two-dimensional distribution function of the uniform zone length and the central magnetic field intensity, the dimension parameters of the low leakage magnetic excitation coil corresponding to the target magnetic induction intensity and the target uniform zone length are determined by using an interpolation method or a table lookup method; Determining the ratio of the number of inner and outer turns of the low-leakage magnetic excitation coil based on the size parameters and the condition that the magnetic moment of the low-leakage magnetic excitation coil is zero; The low leakage magnetic excitation coils include a first group 1, 2 and a second group 3, 4, and the condition for the magnetic moment to be zero is: N 34 =k r N 12 ; Among them, N 12 and N 34 The number of turns of the first coil 1, 2 and the second coil 3, 4, respectively, r 12 and r 34 are the radii of the first set of coils 1 and 2 and the second set of coils 3 and 4 respectively; d 12 and d 34 are the thicknesses of the first set of coils 1 and 2 and the second set of coils 3 and 4 respectively; the radial integral variable h is the height from the inner diameter of the coil to the integration point along the radial direction; d 12 and d 34 It is equal to the number of coil winding layers multiplied by the diameter of the enameled wire.

2. The method for designing a low leakage magnetic excitation coil capable of generating a highly uniform magnetic field according to claim 1, characterized in that: Before determining the target magnetic induction intensity and the target uniform area length, the method further includes: Based on the steady-state magnetic induction intensity formula, the first functional relationship between the low leakage magnetic excitation coil constant and the number of coil turns, size and position is determined; Based on the uniformity length, determining a second functional relationship between the uniformity length and the number of coil turns, the size, and the position; Based on the first functional relationship and the second functional relationship, a two-dimensional distribution function of the uniform area length and the central magnetic field intensity is constructed.

3. The method for designing a low-leakage magnetic excitation coil capable of generating a highly uniform magnetic field according to claim 2, characterized in that: The constructing of a two-dimensional distribution function of the uniform area length and the central magnetic field intensity based on the first functional relationship and the second functional relationship includes: Determine the constraints of zero magnetic moment and centrosymmetry respectively; Based on the constraint conditions and in combination with the first functional relationship and the second functional relationship, a two-dimensional distribution function of the uniform area length and the central magnetic field intensity is constructed.

4. The method for designing a low-leakage magnetic field coil capable of generating a highly uniform magnetic field according to claim 3, wherein: The constraint condition for the magnetic moment to be zero is: N1r1 2 +N2 2 r2 2 =N3 2 r3 2 +N4 2 r4 2 ; The central symmetry constraint is: r1=r2; r3=r4; N1=N2; N3=N4; x1=-x2=-r1 / 2; x3=-x4=-r3 / 2; Where r1 and r2 represent the radius of the coils of the first group 1 and 2 respectively, r3 and r4 represent the radius of the coils of the second group 3 and 4 respectively, N1 and N2 represent the number of turns of the coils of the first group 1 and 2 respectively, N3 and N4 represent the number of turns of the coils of the second group 3 and 4 respectively, x1 and x2 represent the positions of the coils of the first group 1 and 2 on the x-axis respectively, and x3 and x4 represent the positions of the coils of the second group 3 and 4 on the x-axis respectively.

5. The method for designing a low-leakage magnetic field coil capable of generating a highly uniform magnetic field according to claim 4, wherein: The constructing of a two-dimensional distribution function of the uniform region length and the central magnetic field intensity based on the constraint condition and in combination with the first functional relationship and the second functional relationship includes: Based on the constraint conditions, combining the first functional relationship and the second functional relationship, a coil constant constraint function and a uniform region length constraint function are obtained; Based on the preset number of turns, the coil constant constraint function and the uniform region length constraint function are optimized to obtain a two-dimensional distribution function of the uniform region length and the central magnetic field intensity.

6. The method for designing a low-leakage magnetic field coil capable of generating a highly uniform magnetic field according to claim 5, characterized in that: The coil constant constraint function is: K B =f1(N 12 ,N 34 ,r 12 ,r 34 ); The uniform region length constraint function is: X L =f2(N 12 ,N 34 ,r 12 ,r 34 ); Among them, K B Indicates the low leakage magnetic field coil constant, X L represents the length of the uniform area; r 12 and r 34 are the radii of the coils numbered 1 and 2 in the first group and 3 and 4 in the second group respectively; 12 and N 34 are the numbers of turns of the first group 1, 2 and the second group 3, 4 coils respectively, f1 represents the first functional relationship, and f2 represents the second functional relationship.

7. The method for designing a low-leakage magnetic excitation coil capable of generating a highly uniform magnetic field according to claim 6, wherein: The two-dimensional distribution function of the uniform area length and the central magnetic field intensity is: (K B ,X L )=f12(r 12 ,r 34 ); (r 12 ,r 34 )=f12 -1 (K B ,X L ); Among them, f12 -1 It is the inverse function of f12.

8. The method for designing a low-leakage magnetic field coil capable of generating a highly uniform magnetic field according to any one of claims 2 to 7, wherein: The steady-state magnetic induction intensity formula is: B=S i＝1 4 S j＝1 NiL [μ0I / 2(N i / N iL L i )][(x i +L i / 2-x) / (R ij 2 +(x i +L i / 2-x) 2 ) 3 / 2 + (-x i +L i / 2+x) / (R ij 2 +(-x i +L i / 2+x) 2 ) 3 / 2 ]; Where μ0 is the vacuum permeability, xi is the x-axis coordinate of point i on the axis, x1, x2, x3, x4 are the x-axis positions of the first coil 1, 2 and the second coil 3, 4 respectively, r1, r2, r3, r4 are the radii of the first coil 1, 2 and the second coil 3, 4 respectively, R ij is the radius of the jth layer of the ith coil, N iL is the total number of layers of the i-th coil, N i is the number of turns of the i-th coil, I represents the current, L i represents the spacing of the i-th coil.

9. A low leakage magnetic field coil design device capable of generating a highly uniform magnetic field, characterized in that: include: A first determination module is used to determine the target magnetic induction intensity and the target uniform area length; A second determination module is configured to determine, based on a pre-constructed two-dimensional distribution function of the uniform zone length and the central magnetic field intensity, the size parameters of the low leakage magnetic excitation coil corresponding to the target magnetic induction intensity and the target uniform zone length by using an interpolation method or a table lookup method; a third determining module, configured to determine a ratio of inner and outer turns of the low-leakage magnetic excitation coil based on the size parameter and a condition that the magnetic moment of the low-leakage magnetic excitation coil is zero; The low leakage magnetic excitation coils include a first group 1, 2 and a second group 3, 4, and the condition for the magnetic moment to be zero is: N 34 =k r N 12 ; Among them, N 12 and N 34 The number of turns of the first coil 1, 2 and the second coil 3, 4, respectively, r 12 and r 34 are the radii of the first set of coils 1 and 2 and the second set of coils 3 and 4 respectively; d 12 and d 34 are the thicknesses of the first set of coils 1 and 2 and the second set of coils 3 and 4 respectively; the radial integral variable h is the height from the inner diameter of the coil to the integration point along the radial direction; d 12 and d 34 It is equal to the number of coil winding layers multiplied by the diameter of the enameled wire.

10. An electronic 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 low-leakage magnetic excitation coil capable of generating a highly uniform magnetic field as claimed in any one of claims 1 to 8 is implemented.

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