Coupling coil based on minkowski structure, coupling mechanism and wireless energy transmission system

Abstract

The application discloses a coupling coil based on Minkowski structure, comprising: a single-turn coupling coil composed of a wire; the single-turn coupling coil is routed along the outline of a novel first-order Minkowski fractal structure from a wire input end, and a wire output end is led out when a loop is followed, and the single-turn coupling coil is jointly formed; the outline of the novel first-order Minkowski fractal structure is a novel outline formed by recessing the outline of the first-order Minkowski fractal structure by a depth of a preset proportion of the side length of a square block at four square block concave parts; the preset proportion is less than 100%; and the single-turn coupling coil is used for a coupling mechanism of a wireless energy transmission system. The application designs a wireless power transmission system coupling coil based on Minkowski structure based on fractal geometry theory, improves the situation that mutual inductance and coupling coefficient of a traditional coupling mechanism are low when transmission distance is increased and the coupling coil is offset, and improves the energy transmission efficiency of the wireless power transmission system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless power transmission, and more particularly to a coupling coil based on Minkowski structure, a coupling mechanism and a wireless power transmission system. BACKGROUND

[0002] Wireless power transmission technology (WPT) has been increasingly widely applied in the fields of electric vehicles, intelligent electronic devices and implantable medical devices, and has a good development prospect.

[0003] The coupling mechanism is an extremely important component of the WPT system (wireless power transmission system or wireless power transmission system), which realizes wireless transmission and reception of energy. With the rapid development of WPT technology, the design requirements for the coupling mechanism are also getting higher and higher. The research on the coupling mechanism can be divided into three angles: transmission coil structure, compensation network structure and electromagnetic shielding structure, among which the transmission coil has the most significant influence on the transmission performance of the coupling mechanism.

[0004] However, the traditional coupling mechanism often adopts a simple coil (for example: a rectangular coil) design, thereby limiting the energy transmission distance and transmission efficiency, especially when the transmission distance increases and the coil is offset, the energy transmission efficiency will be greatly reduced. Therefore, it is urgent to optimize the structure of the existing coupling coil to improve the energy transmission distance, energy transmission efficiency and anti-offset capability of the WPT system. SUMMARY

[0005] In view of at least one defect or improvement demand of the prior art, the present application provides a coupling coil based on Minkowski structure, a coupling mechanism and a wireless power transmission system, which are used to improve the energy transmission distance, energy transmission efficiency and anti-offset capability of the existing WPT system.

[0006] To achieve the above-mentioned purpose, in a first aspect, the present application provides a coupling coil based on Minkowski structure, comprising: a single-turn coupling coil composed of a wire;

[0007] The single-turn coupling coil starts from the wire input end, follows the new 1st-order Minkowski fractal structure contour line, and leads out the wire output end when looping the wire one turn, to jointly constitute the single-turn coupling coil;

[0008] The new 1st-order Minkowski fractal structure contour line is a new contour line formed by recessing the 1st-order Minkowski fractal structure contour line at four square concave parts by a depth of a preset proportion of the square side length; the preset proportion is less than 100%.

[0009] The single-turn coupling coil is used for a coupling mechanism of a wireless power transmission system.

[0010] Further, it further comprises a bearing mechanism for bearing the single-turn coupling coil.

[0011] A surface of the bearing mechanism is pre-provided with an embedded wire groove.

[0012] The embedded wire groove follows the wire direction of the single-turn coupling coil.

[0013] The single-turn coupling coil is fixed in the embedded wire groove by means of clamping or sticking.

[0014] Further, the preset proportion is 25% to 75%.

[0015] Further, the end of the wire input end and the wire output end is provided with a joint.

[0016] In the second aspect, the application provides a coupling coil based on Minkowski structure, comprising: a multi-turn coupling coil composed of wires.

[0017] The outermost layer of the multi-turn coupling coil starts from the wire input end, follows the outer contour line of the new 1st-order Minkowski fractal structure, and after one loop, continues to follow the outer contour line of the new 1st-order Minkowski fractal structure with a preset equal proportion scaling inward, and so on, until the wire output end is led out after multiple loops, which together constitute the multi-turn coupling coil.

[0018] The outer contour line of the new 1st-order Minkowski fractal structure with a preset equal proportion scaling comprises that the bottom edge segments of the four concave parts of the outer contour line of the new 1st-order Minkowski fractal structure are gradually lengthened by a preset first proportion, and other edge segments except the bottom edge segments of the four concave parts are gradually shortened by a preset second proportion.

[0019] The outer contour line of the new 1st-order Minkowski fractal structure is a new outer contour line formed by the depth of the four square concave parts of the 1st-order Minkowski fractal structure being recessed by a preset proportion of the square edge length; the preset proportion is less than 100%.

[0020] The multi-turn coupling coil is used for a coupling mechanism of a wireless power transmission system.

[0021] Further, it further comprises a bearing mechanism for bearing the multi-turn coupling coil.

[0022] A surface of the bearing mechanism is pre-provided with an embedded wire groove.

[0023] The slotting direction of the embedded wire slot follows the wire direction of the multi-turn coupling coil;

[0024] The multi-turn coupling coil is fixed to the embedded wire slot by means of clamping or sticking.

[0025] Further, the preset ratio is 25% to 75%.

[0026] Further, the end of the wire input end and the wire output end is provided with a joint.

[0027] In a third aspect, the application provides a coupling mechanism based on Minkowski structure, wherein the single-turn coupling coil of any one of the preceding aspects is arranged at the transmitting end and the receiving end of the coupling mechanism, or the multi-turn coupling coil of any one of the preceding aspects is arranged at the transmitting end and the receiving end of the coupling mechanism.

[0028] In a fourth aspect, the application provides a wireless energy transmission system based on Minkowski structure, wherein the wireless energy transmission system is based on the coupling mechanism of the preceding aspect.

[0029] Overall, compared with the prior art, the above technical solutions conceived by the application can achieve the following beneficial effects:

[0030] The application designs a wireless energy transmission system coupling coil based on Minkowski structure based on fractal geometry theory, improves the low mutual inductance and coupling coefficient of the traditional coupling mechanism when the transmission distance increases and the coupling coil deviates, and improves the energy transmission efficiency of the wireless energy transmission system. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings required to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0032] Figure 1 The coupling mechanism equivalent model diagram provided for the embodiments of the application;

[0033] Figure 2 The step-by-step evolution diagram of the Minkowski fractal structure provided for the embodiments of the application;

[0034] Figure 3 The curve evolution diagram from the outer contour line of the first-order Minkowski fractal structure to the outer contour line of the new first-order Minkowski fractal structure provided for the embodiments of the application;

[0035] Figure 4 A planar structure view of the multi-turn coupling coil based on the Minkowski structure is provided for the embodiments of the present application;

[0036] Figure 5 A three-dimensional structure view of the coupling mechanism (coupling device) composed of the multi-turn coupling coil based on the Minkowski structure is provided for the embodiments of the present application;

[0037] Figure 6 A structural schematic diagram of the wireless energy transmission system based on the Minkowski structure is provided for the embodiments of the present application;

[0038] Figure 7 A group of simulation curve diagrams of the performance of the multi-turn coupling coil based on the Minkowski structure changing with the transmission distance is provided for the embodiments of the present application;

[0039] Figure 8 A simulation drawing of the multi-turn coupling coil based on the Minkowski structure in the offset state is provided for the embodiments of the present application;

[0040] Figure 9 A group of simulation curve diagrams of the performance of the multi-turn coupling coil based on the Minkowski structure changing with the offset distance is provided for the embodiments of the present application;

[0041] Figure 10 A planar structure view of a traditional multi-turn rectangular coil matched with the parameters of the multi-turn coupling coil based on the Minkowski structure is provided for the embodiments of the present application; Figure 4

[0042] Figure 11 A group of experimental curve diagrams of the performance of the multi-turn coupling coil based on the Minkowski structure changing with the transmission distance is provided for the embodiments of the present application;

[0043] Figure 12 A group of experimental curve diagrams of the performance of the multi-turn coupling coil based on the Minkowski structure changing with the offset distance is provided for the embodiments of the present application. DETAILED DESCRIPTION

[0044] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0045] ​The terms "comprising" or "having," and any variations thereof, in the specification, claims, or drawings of this application are intended to cover a non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such processes, methods, products, or apparatus.

[0046] As described in the background section of this specification, traditional coupling mechanisms often employ simple coil designs (e.g., rectangular coils), which limits energy transmission distance and efficiency. This is especially true when dealing with increased transmission distance and coil misalignment, where energy transmission efficiency often drops significantly. Therefore, this application provides a coupling coil, coupling mechanism, and wireless power transfer system based on a Minkowski structure to improve the energy transmission distance, energy transmission efficiency, and misalignment resistance of existing WPT systems.

[0047] This application first conducts a theoretical analysis and study on the basic structural composition and principle of coupling coils and coupling mechanisms based on the Minkowski structure; secondly, it constructs the model in the Comsol multiphysics finite element tool and verifies it through experiments; finally, it summarizes the experimental conclusions and analyzes the advantages of coupling coils and coupling mechanisms based on the Minkowski structure compared with traditional coupling coils and coupling mechanisms, as well as their application scenarios.

[0048] like Figure 1 The diagram shown is an equivalent model of the coupling mechanism of a wireless power transmission system. Figure 1 As can be seen, the coupling mechanism of a wireless power transmission system consists of two basic parts: the power transmitting end (…). Figure 1 (left side) and power receiving end ( Figure 1 (Right side). Among them The magnetic flux of the primary and secondary coils in the magnetic core; The leakage flux generated by the primary and secondary coils; L1 is the equivalent magnetic flux after the primary and secondary coil turns are linked; L1, L2, and M are the self-inductance of the primary side, the self-inductance of the secondary side, and the mutual inductance between the two, respectively; the number of turns on both sides are denoted as N1 and N2, respectively.

[0049] Establish Figure 1 The mutual inductance model of the wireless power transfer system shown can be represented as follows:

[0050]

[0051] Therefore, the mutual inductance in the formula can be expressed as:

[0052]

[0053] In subsequent experimental studies, one embodiment of this application uses the coupling coefficient k to characterize the magnetic coupling performance between the Minkowski structure coupled coil and the conventional coil:

[0054]

[0055] During coil design, it's important to note that changes in coil size, turn spacing, and wire diameter can alter coil performance. These parameters require careful consideration when selecting the operating frequency for experimental research. The coil resistance R can be calculated as follows:

[0056]

[0057] The self-inductance of the coil can also be approximately calculated using the following formula:

[0058]

[0059] Where ρ represents the resistivity of the conductor, r represents the radius of the conductor, l represents the length of the coil, A represents the cross-sectional area of ​​the conductor, μ0 represents the permeability of free space, and μ r The value represents the relative permeability of the coil material, l represents the average length of the coil, and N represents the number of turns.

[0060] Based on the above formula derivation and combined with the actual equipment of the experimental platform, the operating frequency f of the experimental system can be determined. s =85kHz.

[0061] Figure 2 This is a diagram showing the step-by-step evolution of the Minkowski fractal structure. The Minkowski fractal structure is a typical fractal geometry; its construction involves creating a large square (…). Figure 2 The 0th-order Minkowski fractal structure on the left is divided into nine identical small squares (a nine-square grid division operation), with five small squares retained on the two diagonals. Figure 2 The centrally located first-order Minkowski fractal structure (consisting of five small black-filled squares along the two diagonals shown) is iterated and truncated according to this pattern to form Minkowski fractal structures of various orders. For example, Figure 2 The second-order Minkowski fractal structure on the right is based on the first-order Minkowski fractal structure. Each of the five black-filled small squares in the first-order Minkowski fractal structure is divided into a nine-square grid, and the smaller squares on the two diagonals are retained.

[0062] The core features of Minkowski fractal structure are in two aspects of self-similarity and fractal dimension. For a fractal geometry F, its Hausdorff dimension can be calculated by the following formula:

[0063]

[0064] Where, n s is the number of self-similar copies under the similar change, r s is the shrinkage ratio of the similar transformation.

[0065] According to the fractal geometry theory, the similar ratio r s of the Minkowski fractal structure is 1 / 3, and the number of copies n s =5 after each iteration.

[0066] Therefore, its Hausdorff dimension is:

[0067]

[0068] According to the above results, it can be judged that the Hausdorff dimension of the Minkowski fractal structure is 1.465, which means that it has good space filling characteristics. The growth rate of the Minkowski fractal structure in the mutually orthogonal directions is the same, and it has the same scaling factor, and each part is similar to the whole. The Minkowski fractal structure is used in many fields due to its isotropy and self-similarity, especially in the design of radar antennas. The radar antenna designed with Minkowski fractal structure has high transmission efficiency.

[0069] Referring to Figure 3 , one embodiment of the present application provides a coupling coil based on Minkowski structure, comprising: a single-turn coupling coil composed of a wire.

[0070] The single-turn coupling coil starts from the wire input end, follows the new 1st-order Minkowski fractal structure contour line, and leads out the wire output end when looping the wire, to jointly constitute the single-turn coupling coil of the coupling mechanism for the wireless energy transmission system.

[0071] The new 1st-order Minkowski fractal structure contour line is a new contour line presented by the depth of the 1st-order Minkowski fractal structure contour line in the four square concave parts, which is recessed by a preset proportion of the square side length; the preset proportion is less than 100%.

[0072] Figure 3 The five black filled small squares of the 1st-order Minkowski fractal structure constitute the 1st-order Minkowski fractal structure, and the external contour line of the 1st-order Minkowski fractal structure is the 1st-order Minkowski fractal structure contour line, for referenceFigure 3 The outline is formed by the green dashed line and the green solid line. The new first-order Minkowski fractal structure outline is a new outline (a closed frame line composed of the green thick solid line and the black thick solid line) formed by moving the bottom edge of the four concave squares (i.e., the four small squares at the top, bottom, left and right) outward by a predetermined distance (i.e., the bottom edge of the green dashed line moves outward to the black solid line).

[0073] The outline of a first-order Minkowski fractal structure is formed by slightly shallower concavity at the four concave squares (the concavity depth does not reach the side length of the small square). However, in reality, deeper concavity affects transmission efficiency, while shallower concavity affects anti-misalignment capability. Therefore, after extensive experimentation, it has been found that the optimal ratio of 25% to 75% (i.e., a concavity depth of 25% to 75% of the side length of the small square) achieves the maximum combined performance in terms of transmission efficiency and anti-misalignment capability.

[0074] Figure 3 The input and output ends of the conductor are not shown in the paper. The key point of this application is that the conductor follows the outline of the so-called novel first-order Minkowski fractal structure in a loop. As for which two points on the outline of the novel first-order Minkowski fractal structure the input and output ends of the conductor are led out, there is no strict limitation.

[0075] Similarly, refer to Figure 4 Another embodiment of this application provides a coupling coil based on a Minkowski structure, comprising: a multi-turn coupling coil composed of wires.

[0076] The outermost turn of the multi-turn coupling coil starts from the wire input end and follows the outline of the aforementioned novel first-order Minkowski fractal structure. After one turn, the outermost turn continues to follow the outline of the novel first-order Minkowski fractal structure scaled in a preset proportion. This process is repeated inwards turn by turn until the wire output end is led out after multiple turns, together forming a multi-turn coupling coil for the coupling mechanism of a wireless power transmission system.

[0077] The new first-order Minkowski fractal structure outline is a new outline presented by the depth of the four square concave parts of the first-order Minkowski fractal structure concave to a predetermined proportion of the square side length. The predetermined proportion is less than 100%, preferably 25% to 75%, as discussed previously and will not be repeated here.

[0078] The new 1st order Minkowski fractal structure outline with preset equal scaling includes the bottom edge segments of the four concave places of the new 1st order Minkowski fractal structure outline gradually lengthened in preset first proportion in each circle (see the dotted line in the figure Figure 4 The bottom edge segments of the four concave places are gradually lengthened in each circle, and the other segments of the new 1st order Minkowski fractal structure outline except the bottom edge segments of the four concave places are gradually shortened in preset second proportion in each circle.

[0079] The reason why the outermost circle of the new 1st order Minkowski fractal structure outline is not gradually reduced in each circle in preset proportion is that the concave places of the inner circle of the reduced new 1st order Minkowski fractal structure outline cannot cover the concave places of the outer circle of the new 1st order Minkowski fractal structure outline, that is, if they are reduced in equal proportion, a multi-turn structure cannot be formed in engineering. The multi-turn coupling coil is actually an approximately shaped multi-turn mode formed by further winding the aforementioned single-turn coupling coil inward, and the inventive concept is similar in nature.

[0080] In some embodiments, the wire is a Litz wire. A Litz wire is a wire composed of multiple individually insulated conductors twisted or braided together. This structure allows the electromagnetic field to be evenly distributed, thereby reducing the effects of skin effect and proximity effect on current distribution. Litz wire is widely used in high-frequency inductors, transformers, frequency converters, fuel cells, motors, communication and IT equipment, and other applications due to its good flexibility and high-frequency performance.

[0081] The single-turn coupling coil and the multi-turn coupling coil of the present application are both composed of a coil wound by a Litz wire with a wire diameter of 2 mm and a rectangular acrylic base plate with a pre-embedded wire slot. They can be fixed by using glue or a hoop.

[0082] A slot is opened on a 200mm*200mm acrylic plate. The cross section of the opened slot is a circumscribed square of the cross section of the aforementioned Litz wire (i.e., the circumscribed square of the new 1st order Minkowski fractal structure outline), and the slot direction is the winding direction of the wire of the coupling coil. Then, a hole is drilled at the end of the wire near the center of the acrylic plate, with a diameter slightly larger than the wire diameter, for leading out the wire.

[0083] In some embodiments, the specific manufacturing method of the aforementioned multi-turn coupling coil comprises: making a new 1st-order Minkowski fractal structure outline slightly smaller than a 200mm*200mm square, winding a fixed length of wire (the length of the wire should meet the length of the rectangular inner spiral coil with equivalent manufacturing cost or equivalent economic benefit) along the outermost contour of the fractal structure, folding the wire inward by about 90° at an appropriate position on the fourth side of the circumscribed square, then continuing to wind along the contour scaled by the center of the square, and repeating the operation until the fixed length of wire is used up, and then connecting another piece of wire at the end of the wire and leading it out in a direction perpendicular to the plane. Figure 4 , starting from the wire input end, winding along the new 1st-order Minkowski fractal structure outline, continuing to wind inward along the contour of the outermost wire after winding nearly one turn, until the fixed length of wire is used up at the wire output end, then connecting another piece of wire at the end of the wire and leading it out in a direction perpendicular to the plane of the acrylic plate. The two final ends of the Litz wire (the aforementioned wire output end and wire input end) are placed in a tin furnace to melt and install a connector for connection to other equipment.

[0084] Reference Figure 5 One embodiment of the present application also provides a coupling mechanism based on Minkowski structure, wherein the transmitting end and the receiving end of the coupling mechanism are provided with the single-turn coupling coil according to any one of the preceding embodiments, or the transmitting end and the receiving end of the coupling mechanism are provided with the multi-turn coupling coil according to any one of the preceding embodiments. Figure 5 The three-dimensional structure view of the coupling mechanism (coupling device) composed of the multi-turn coupling coil based on Minkowski structure provided by the embodiment of the present application is shown in Figure 5 It can be seen that the two multi-turn coupling coils are placed oppositely and together equivalent to Figure 1 the equivalent model of the coupling mechanism shown in the figure. In Figure 1 , the wire input end and the wire output end of the multi-turn coupling coil on one side correspond to the positive and negative electrodes on the side, and the multi-turn coupling coil on the other side corresponds accordingly. The three-dimensional structure view of the coupling mechanism (coupling device) composed of the single-turn coupling coil is not shown in the figure, but it is the same as the coupling mechanism composed of the multi-turn coupling coil, which will not be described here.

[0085] One embodiment of the present application also provides a wireless energy transmission system based on Minkowski structure, wherein the wireless energy transmission system is based on the coupling mechanism according to the preceding embodiments. Reference Figure 6 , the coupling mechanism composed of the single-turn coupling coil or the coupling mechanism composed of the multi-turn coupling coil is placed in the coupling device Figure 6 , and together with other components, it constitutes the wireless energy transmission system based on Minkowski structure.

[0086] Figure 5 Also the model of the coupling mechanism based on the serially wound Minkowski coil (i.e. the low-density multi-turn coupling coil based on the Minkowski structure, i.e. the multi-turn coupling coil with fewer turns wound for three or four turns) established in the Comsol simulation tool, in this embodiment, the specific size parameters of the model are shown in Table 1 below.

[0087] Table 1 Size parameter table of serially wound Minkowski coil

[0088]

[0089] For the serially wound Minkowski coil, the traditional rectangular coil is used as the reference object in this embodiment, and due to the inherent difference between the two types of coil shapes, it is not possible to construct a rectangular coil with completely consistent parameters. Therefore, this embodiment adopts a systematic modeling and analysis method, by fixing the area and turn spacing of the coil, respectively changing the length and number of turns of the rectangular coil, which are two variables that have a more significant impact on the coupling performance, to construct two traditional rectangular coil models.

[0090] The parameter settings of the three coils are shown in Table 2, and the material type, physical field selection, mesh division method and research method of each coil are the same. Through this method, a comprehensive and reliable comparison benchmark is provided to comprehensively evaluate the performance of the fractal coil.

[0091] Table 2 Parameter setting table of three coils

[0092]

[0093] Define the coupling coefficient decay rate: when the coil position changes, the ratio of the difference between the initial coupling coefficient and the current coupling coefficient to the initial coupling coefficient, and its expression is:

[0094]

[0095] First, in this embodiment, the transmission distance of 3 different types of coils is studied, and the characteristic curves of mutual inductance and coupling coefficient with the change of transmission distance are obtained. According to the simulation results shown in Figure 7 According to the simulation results shown in

[0096] According to the simulation results shown in Figure 7(d) It can be seen that when the transmission distance is less than 3.5 cm, the mutual inductance of the series-wound Minkowski coil is higher than that of the rectangular coil I and lower than that of the rectangular coil II; in the range of 3.5 cm to 20 cm, the mutual inductance of the series-wound Minkowski coil is similar to that of the rectangular coil I, while the mutual inductance of the rectangular coil II is always higher than that of the other two coils. This shows that the number of turns of the coil has a significant impact on mutual inductance. In the case of the same number of turns, the series-wound Minkowski coil can maintain a high mutual inductance value as the transmission distance increases. In the case of equal coil length, due to the existence of more inflection points in the structure of the series-wound Minkowski coil, local magnetic field interference occurs, resulting in a mutual inductance value lower than that of the rectangular coil II.

[0097] From Figure 7 (e) and Figure 7 (f), it can be seen that the coupling coefficient of the series-wound Minkowski coil is always lower than that of the traditional rectangular coil, and its coupling coefficient decay rate is always higher than that of the traditional rectangular coil. Analysis shows that this is also due to the existence of more inflection points in the fractal structure of the series-wound Minkowski coil, which increases the interaction between coils. Due to the inherent characteristics of its structure, the turn spacing changes at local positions, affecting the uniform distribution of the magnetic field, resulting in a large fluctuation in the coupling coefficient when the position changes. This characteristic can bring advantages in certain specific applications, such as in situations that require a specific magnetic field distribution, but at the same time it also brings challenges to application scenarios that require a stable coupling coefficient.

[0098] In summary, when the number of turns is the same, the so-called series-wound Minkowski coil has certain advantages when the transmission distance increases slightly, but its coupling coefficient is relatively low, and the coupling coefficient decay rate is also relatively high. In addition, increasing the number of turns of the coil is an important method to improve the coupling coefficient and mutual inductance. In further optimization, improving the coupling effect of the series-wound Minkowski coil should be the research direction. The coupling effect can be improved through structure optimization and dynamic adjustment design, etc., so as to expand the application scenarios.

[0099] Then, as Figure 8 shown, the anti-offset performance of three different types of coils was studied in this embodiment, and the characteristic curves of the mutual inductance and coupling coefficient with the offset distance were obtained.

[0100] From Figure 9(d) It can be seen that when the offset distance is less than 3 cm, the mutual inductance of the series-wound Minkowski coil is higher than that of the rectangular coil I, but lower than that of the rectangular coil II; in the offset distance range of 3 cm to 10 cm, the mutual inductance of the series-wound Minkowski coil is lower than that of the traditional rectangular coil. In the whole offset process, the mutual inductance of the rectangular coil II is always greater than that of the series-wound Minkowski coil and the rectangular coil I. This shows that under the condition of the same number of turns, the series-wound Minkowski coil can still maintain better characteristics than the traditional rectangular coil when the offset distance is small, and once the offset exceeds this threshold, its mutual inductance is lower than that of the traditional rectangular coil.

[0101] By Figure 9 (e), Figure 9 (f) It can be seen that the coupling coefficient of the series-wound Minkowski coil is always lower than that of the traditional rectangular coil, and its coupling coefficient decay rate is always higher than that of the traditional rectangular coil. The reason is the same as before, the more inflection points of the series-wound Minkowski coil increase the interaction between the coils, affecting the uniform distribution of the magnetic field, resulting in a larger fluctuation of the coupling coefficient when the coil is offset.

[0102] In combination with the experimental results, when the number of turns is the same, the series-wound Minkowski coil has certain advantages at a small offset, but its coupling coefficient is relatively low, and the coupling coefficient decay rate is also relatively high. In addition, increasing the number of turns of the coil is an important method to enhance the anti-offset performance of the coil.

[0103] In summary, the series-wound Minkowski coil has certain advantages in coupling effect when the transmission distance increases slightly, but its coupling coefficient is relatively low and the coupling coefficient decay rate is also relatively high when the transmission distance exceeds the threshold. The series-wound Minkowski coil maintains better characteristics than the traditional rectangular coil at a small offset, but its mutual inductance will be lower than that of the traditional rectangular coil when the offset distance exceeds a certain threshold. The improvement scheme is to increase the number of turns, and to improve the coupling effect through structure optimization and dynamic parameter adjustment.

[0104] The series-wound Minkowski coil and the traditional rectangular coil with parameters matched therewith as shown in Table 1 data are actually made, as shown in Figure 4 and Figure 10 In this embodiment, the TH2832 LCR bridge is used to measure mutual inductance and self-inductance. The wireless power transmission system is as shown in Figure 6As shown, the transmitting end outputs direct current from a direct current power supply, which is converted into alternating current of a specific frequency by a high-frequency inverter module and sent to the primary coupling coil. Based on the principle of electromagnetic induction, the coil converts the current into an alternating electromagnetic field, which induces an alternating electromotive force in the secondary coupling coil. The secondary coupling coil of the receiving end captures these electromagnetic fields, and the alternating current is rectified into direct current by a high-frequency rectifier module to supply the load.

[0105] In this embodiment, after the measurement is completed, the mutual inductance, coupling coefficient and its decay rate between the coils are first calculated. Then, the data is grouped and a curve is drawn to visually observe the trend of each parameter. Next, the performance difference between the series-wound Minkowski coil and the traditional rectangular coil will be compared. The actual experimental data of the transmission distance obtained are as follows Figure 11 As shown, the actual experimental data of the anti-offset performance are as follows Figure 12

[0106] In the research experiment of the transmission distance of the series-wound Minkowski coil, it can be known from Figure 11 (a) that, when the transmission distance is in the range of 3cm to 9cm, the mutual inductance value and the coupling coefficient of the series-wound Minkowski coil are lower than the corresponding values of the traditional rectangular coil; and when the transmission distance is greater than 9cm, the mutual inductance values of the two kinds of coils are similar, and the coupling coefficient of the series-wound Minkowski coil is slightly higher than that of the traditional rectangular coil.

[0107] It can be known from Figure 11 (b) that, when the transmission distance changes, the coupling coefficient decay rate of the series-wound Minkowski coil is low, which indicates that the decay of its coupling performance is small.

[0108] In the anti-offset research experiment of the series-wound Minkowski coil, it can be known from Figure 12 (a) that, when the offset distance is less than 3cm and greater than 6.5cm, the mutual inductance value and the coupling coefficient of the series-wound Minkowski coil are slightly higher than the corresponding values of the rectangular coil, and in other cases, the parameters of the two kinds of coils are similar.

[0109] It can be known from Figure 12 (b) that, when the offset distance is less than 4cm, the coupling coefficient decay rate of the series-wound Minkowski coil is lower than that of the traditional rectangular coil; and when the offset distance is greater than 4cm, the parameters of the two kinds of coils are similar, which is consistent with the simulation results.

[0110] ​It can be seen that the coupling performance of the series wound Minkowski coil is slightly better than that of the traditional rectangular coil when transmitting at a long distance, and the coupling coefficient decay rate is lower. In the case of small and large distance offset, its coupling performance is better than that of the traditional rectangular coil; while in the case of medium distance offset, its performance is slightly worse than that of the rectangular coil. But with the increase of the offset distance, its coupling coefficient decay rate is always lower than that of the traditional rectangular coil, so its anti-offset performance is better in certain cases, and it is suitable for specific WPT systems prone to offset. The design also shows that tight winding has an important influence on improving the coupling characteristics of the coil.

[0111] The present application uses fractal geometry theory and experimental verification to prove the potential advantages of Minkowski structure coupling coil in improving the performance of the coil, designs a wireless power transmission system coupling mechanism based on Minkowski structure, improves the low mutual inductance and coupling coefficient of the traditional coupling mechanism when the transmission distance increases and the coupling coil is offset, and improves the energy transmission efficiency of the wireless power transmission system.

[0112] Those skilled in the art can understand that the technical features described in various embodiments and / or claims of the present application can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present application. In particular, the technical features described in various embodiments and / or claims of the present application can be combined and / or combined in various ways without departing from the spirit and teachings of the present application, and all such combinations and / or combinations fall within the scope of the present application.

[0113] Although the present application has been shown and described with reference to certain exemplary embodiments thereof, it should be understood by those skilled in the art that various changes in form and detail can be made therein without departing from the spirit and scope of the present application as defined by the appended claims and their equivalents. Therefore, the scope of the present application should not be limited to the above-described embodiments, but should be determined only by the appended claims, and should be defined by the appended claims and their equivalents.

Claims

1. A Minkowski structure based coupling coil, characterized in that, The application relates to a multi-turn coupling coil formed by a wire. The outermost layer of the multi-turn coupling coil is routed along an adjusted type 1 Minkowski fractal structure contour line from a wire input end, and after one turn, the wire is routed along the adjusted type 1 Minkowski fractal structure contour line with a preset equal proportion scaling from the outermost layer to the inside, and the wire is gradually routed from the inside to the outside in turns until a wire output end is led out after multiple turns, so as to form the multi-turn coupling coil. The adjusted type 1 Minkowski fractal structure contour line comprises a bottom edge segment of four concave parts of an adjusted type 1 Minkowski fractal structure contour line which is gradually lengthened in turns at a preset first proportion, and other edge segments of the adjusted type 1 Minkowski fractal structure contour line except the bottom edge segment of the four concave parts are gradually shortened in turns at a preset second proportion. The adjusted type 1 Minkowski fractal structure contour line is an adjusted contour line formed by recessing a preset proportion block edge length of a 1 Minkowski fractal structure contour line at four block concave parts. The preset proportion is less than 100%. The multi-turn coupling coil is used for a coupling mechanism of a wireless energy transmission system. The application further comprises a bearing mechanism for bearing the multi-turn coupling coil.

2. The coupling coil of claim 1, wherein, A surface of the bearing mechanism is provided with a wire embedding groove. The wire embedding groove is routed along the wire of the multi-turn coupling coil. The multi-turn coupling coil is fixed to the wire embedding groove by means of clamping or sticking. The preset proportion is 25%-75%.

3. The coupling coil of claim 1, wherein, The wire input end and the wire output end are provided with joints.

4. The coupling coil of claim 1, wherein, The multi-turn coupling coil of any one of claims 1-4 is arranged at a transmitting end and a receiving end of the coupling mechanism.

5. A coupling mechanism based on Minkowski structure, characterized by, The wireless energy transmission system is based on the coupling mechanism of claim 5.

6. A wireless energy transfer system based on Minkowski structures, characterized in that, ​

Images