Composite electromagnetic shielding mechanism for wireless power transmission

Abstract

The invention discloses a composite electromagnetic shielding mechanism for wireless power transmission. The composite electromagnetic shielding mechanism comprises a primary side shielding assembly and a secondary side shielding assembly, each of the primary side shielding assembly and the secondary side shielding assembly comprises a coil, an integrated shielding plate, a heat dissipation plate and an aluminum plate which are sequentially arranged from inside to outside, and the primary side shielding assembly and the secondary side shielding assembly are symmetrically arranged; the integrated shielding plate is formed by compounding ferrite blocks and nanocrystalline strips, wherein the ferrite blocks are distributed in a contact area of a coil winding path and the integrated shielding plate in a matrix arrangement mode; the nanocrystalline strips are distributed in the area, except the ferrite blocks, of the integrated shielding plate to form nanocrystalline plates distributed in double rows; the heat dissipation plate is arranged between the integrated shielding plate and the aluminum plate; the aluminum plate is of an outermost shielding structure.

Description

Technical Field

[0001] The present invention relates to the field of wireless power transmission, and particularly to a composite electromagnetic shielding mechanism for wireless power transmission. Background Art

[0002] Since the high-frequency electromagnetic field generated by a wireless power transmission system can cause varying degrees of damage to organisms, leading to safety problems of organisms, and the heat generation phenomenon generated by the high-frequency electromagnetic field in the shielding mechanism, resulting in a decrease in power transmission efficiency. In addition, the high-frequency electromagnetic field can also interfere with electromagnetic waves, thus affecting normal communication and interfering with human production and life.

[0003] Most existing products use ferrite as electromagnetic shielding. However, due to its low magnetic permeability and easy magnetic saturation, the shielding effect of ferrite is not good. There is also research using nanocrystals to replace ferrite. However, due to its high electrical conductivity, the nanocrystal material has large eddy current losses, so it also has a great adverse impact on the transmission efficiency of the wireless power transmission system. In addition, some research uses a shielding structure with an added aluminum plate. The high electrical conductivity of the aluminum plate results in large eddy current losses at high frequencies. Therefore, there is currently no perfect solution to the problem of maintaining high efficiency and good electromagnetic shielding in the research of electromagnetic shielding for wireless power transmission. Summary of the Invention

[0004] To achieve the above and other related objectives, the present invention discloses a composite electromagnetic shielding mechanism for wireless power transmission, including: A primary side shielding component and a secondary side shielding component; Both the primary side shielding component and the secondary side shielding component include a coil, an integrated shielding plate, a heat dissipation plate, and an aluminum plate arranged in sequence from the inside out. The primary side shielding component and the secondary side shielding component are symmetrically arranged; The integrated shielding plate is composed of a ferrite block and a nanocrystal strip composite, wherein: The ferrite blocks are distributed in the area where the coil winding path contacts the integrated shielding plate in a matrix arrangement; The nanocrystal strips are distributed in the area of the integrated shielding plate except for the ferrite blocks, forming a double-row distributed nanocrystal plate; The heat dissipation plate is arranged between the integrated shielding plate and the aluminum plate; The aluminum plate is the outermost shielding structure.

[0005] Further, the size of the integrated shielding plate is 400mm×400mm.

[0006] Further, the coil is wound into a hollow square, the outer side length of the coil is 300mm, and the inner side length of the hollow square is 200mm.

[0007] Further, the width of the nanocrystalline strip is 50 mm and the thickness is 18 μm.

[0008] Further, heat dissipation holes are formed in the heat dissipation plate.

[0009] Further, the integrated shielding plate is fixed by gluing.

[0010] Further, the aluminum plate, the heat dissipation plate, and the integrated shielding plate have the same size.

[0011] By adopting the above technical solution, when the coil is energized, a high magnetic field region is generated by the coil. After the magnetic field passes through the ferrite shielding layer, at this time, a part of the magnetic focusing effect will be generated on the magnetic field generated by the coil, so that a large amount of magnetic fields are concentrated on the magnetic circuit and reflected back to the magnetic circuit by the ferrite, enhancing the magnetic effect on the coil. In the low magnetic field region, that is, the central and edge regions, nanocrystals with high saturation magnetic flux density and high relative magnetic permeability are placed, which can minimize the shielding thickness of the weak magnetic field region and attract the leakage magnetic flux. The aluminum alloy heat sink is placed between the ferrite nanocrystal single-layer integrated shielding plate and the shielding aluminum plate to prevent the temperature from rising and reducing the saturation magnetic flux, and also prevent the coupling mechanism from overheating. The outermost aluminum plate ensures that the magnetic field is completely shielded. When the magnetic field reaches the outermost aluminum plate, there is basically no leakage magnetic flux outside the shielding layer at this time, achieving a good shielding effect and a high transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In combination with the accompanying drawings and with reference to the following detailed description, the above and other features, advantages, and aspects of the embodiments of the present disclosure will become more apparent. The drawings are used to better understand the solution and do not constitute a limitation to the present disclosure. In the drawings, the same or similar reference numerals represent the same or similar elements, where: Figure 1 is an exploded structural schematic diagram of the present invention; Figure 2 is a schematic diagram of the integrated shielding plate and the coil of the present invention; Figure 3 is a schematic diagram of the heat dissipation plate and the aluminum plate of the present invention.

[0013] Reference numerals: 1, aluminum plate; 2, heat dissipation plate; 3, integrated shielding plate; 4, coil. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of the present invention.

[0015] Refer to Figure 1, an embodiment of the present invention provides a composite electromagnetic shielding mechanism for wireless power transmission, including: a primary side shielding component and a secondary side shielding component; Both the primary side shielding component and the secondary side shielding component include a coil 4, an integrated shielding plate 3, a heat dissipation plate 2, and an aluminum plate 1 arranged in sequence from the inside to the outside. The primary side shielding component and the secondary side shielding component are symmetrically arranged; Referring to Figure 2 , the integrated shielding plate 3 is composed of a composite of ferrite blocks and nanocrystalline tapes, where: The ferrite blocks are distributed in the area where the winding path of the coil 4 contacts the integrated shielding plate 3 in a matrix arrangement; The nanocrystalline tapes are distributed in the area of the integrated shielding plate 3 except for the ferrite blocks, forming a double-row distributed nanocrystalline plate; The heat dissipation plate 2 is arranged between the integrated shielding plate 3 and the aluminum plate 1; The aluminum plate 1 is the outermost shielding structure.

[0016] Among them, the integrated shielding plate 3 is composed of a square nanocrystalline plate, a plate composed of ferrite blocks in a zigzag shape, and a zigzag nanocrystalline plate from the inside to the outside. The outer side length specification of the integrated shielding plate 3 is 400 mm × 400 mm.

[0017] The nanocrystalline plate in this embodiment is composed of nanocrystalline tapes. The nanocrystalline tapes are 1K107, with a width of 50 mm and a thickness of 18 μm. The size of the square nanocrystalline plate is 200 mm × 200 mm. The shielding plate composed of ferrite blocks is located on the periphery of the square nanocrystalline plate. The shielding plate composed of ferrite blocks has a zigzag annular square structure, with an outer side length of 300 mm × 300 mm and an inner side length of the hollow part inside of 200 mm × 200 mm. The size of the ferrite blocks in this embodiment is a matrix block of 50 mm × 50 mm, with a thickness of 1 mm.

[0018] The shape and size of the winding of the coil 4 are the same as those of the shielding plate composed of ferrite blocks, with an outer side length of 300 mm and an inner side length of 200 mm, and the coil 4 is in contact with the shielding plate composed of ferrite blocks.

[0019] Referring to Figure 3 , the sizes of both the heat dissipation plate 2 and the aluminum plate 1 are squares of 400 mm × 400 mm, and the heat dissipation plate 2 is provided with heat dissipation holes.

[0020] The following makes a detailed description of the electromagnetic shielding of the laminated shielding structure for wireless power transmission in this embodiment.

[0021] When the coil 4 is energized, a high magnetic field region is generated by the coil 4. After the magnetic field passes through the ferrite shielding layer, at this time, a part of the magnetic field concentration effect is generated on the magnetic field generated by the coil 4, causing a large amount of magnetic fields to gather on the magnetic path and be reflected back to the magnetic path by the ferrite, enhancing the magnetic field effect on the coil 4. In the low magnetic field regions, that is, the central and edge regions, nanocrystals with high saturation magnetic flux density and high relative magnetic permeability are placed, which can minimize the shielding thickness of the weak magnetic field regions and attract the leakage magnetic flux. The aluminum alloy heat sink is placed between the ferrite nanocrystal single-layer integrated shielding plate 3 and the shielding aluminum plate 1 to prevent the temperature from rising and reducing the saturation magnetic flux, and also to prevent the coupling mechanism from overheating. The outermost aluminum plate 1 ensures that the magnetic field is completely shielded. When the magnetic field reaches the outermost aluminum plate 1, there is basically no leakage magnetic field outside the shielding layer at this time, achieving a good shielding effect and a high transmission efficiency.

[0022] The magnetic field coupling strength between the coils 4 and the spatial leakage magnetic field are two key factors reflecting the system performance, while the self-inductance L and mutual inductance M of the coil 4 are the main parameters used to calculate the coupling coefficient k. Therefore, the calculation of L and M is helpful for analyzing the coupling performance of the system. For a planar spiral coil 4 in free space, the calculation method of its self-inductance is as follows: In the formula, D avg =r in +r out , µ0 is the magnetic permeability of vacuum, n is the number of turns of the coil, r in and r out are the inner radius and outer radius of the coil respectively, c 1 , c 2 , c 3 , c 4 are distribution coefficients, which can be obtained by fitting, and different coils with different shapes have different distribution coefficients.

[0023] When both the transmitting coil and the receiving coil are planar spiral and coaxially placed, the approximate value of the mutual inductance between the two coils is calculated as: In the formula, n 1 , n 2 are the number of turns of the transmitting coil and the receiving coil respectively, r 1 , r 2 are the radii of the transmitting coil and the receiving coil respectively, D is the distance between the transmitting coil and the receiving coil, and F 1 is the hypergeometric function.

[0024] Calculate the magnetic induction intensity generated by different turns of the coil at this point, and after vector superposition, the magnetic induction intensity generated by the multi-turn coil at this point can be obtained. According to the Biot-Savart law, the magnetic induction intensity generated by a current-carrying straight wire at a certain point in space is calculated as: Wherein, I is the current flowing through the wire, s is the distance from the calculation point to the current-carrying wire, and θ 1 and θ 2 are respectively the angles between the connecting lines from both ends of the wire to the calculation point and the wire.

[0025] In the magnetic coupling structure simulation model, the nanocrystalline magnetic core is made by laminating nanocrystalline tapes. The thickness of a single-layer nanocrystalline tape is only 18 μm, and it is impossible to perform layer-by-layer modeling according to the actual situation. A homogenization simulation model of the nanocrystalline magnetic core is established, and the laminated nanocrystalline magnetic core is equivalent to a uniform solid structure with anisotropic permeability and conductivity.

[0026] The calculation formulas for the permeability and conductivity in each direction in the equivalent homogenization model are as follows: Wherein, μ x and μ y and μ z are respectively the permeability of the homogenization model in the tangential direction, rolling direction, and stacking direction; µ is the material permeability; F is the nanocrystalline lamination coefficient; σ x and σ y and σ z are respectively the conductivity of the homogenization model in the tangential direction, rolling direction, and stacking direction; σ is the material conductivity; d and D are respectively the thickness and width of the nanocrystalline tape; µ 0 is the vacuum permeability.

[0027] By establishing a COMSOL model of the electromagnetic shielding structure for wireless power transmission, it can be seen that the ferrite has strong magnetic assistance ability but its shielding effect is not good and the magnetic leakage is large, while the nanocrystalline tape can effectively enhance the magnetic leakage shielding ability, but its eddy current will reduce the transmission efficiency. When using the electromagnetic shielding structure established by this patent, it is possible to enhance the magnetic field coupling while reducing the spatial magnetic leakage, ensuring the safe, reliable, and efficient transmission of electric energy for wireless power transmission. In addition, the composite magnetic shielding structure has relatively good parameter stability, which brings convenience to the numerical analysis and calculation of the electromagnetic field, and is convenient to adjust the winding thickness of the nanocrystalline tape, the thickness of the ferrite, and the transmission distance according to different application scenarios during the actual operation process to ensure its shielding effect and achieve the best transmission performance.

[0028] Those skilled in the art can understand that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the field to which the present invention pertains. It should also be understood that terms such as those defined in a general dictionary should be construed to have a meaning consistent with the meaning in the context of the prior art, and will not be interpreted in an idealized or overly formal sense unless specifically defined.

[0029] For method embodiments, for the sake of simplicity of description, they are all described as a series of combinations of actions. However, those skilled in the art should be aware that the embodiments of the present invention are not limited by the described order of actions, because according to the embodiments of the present invention, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily essential to the embodiments of the present invention.

[0030] From the description of the above embodiments, it can be clearly understood by those skilled in the art that the present application can be implemented by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of the present application.

[0031] 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 them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite electromagnetic shielding mechanism for wireless power transmission, characterized in that: include: Primary side shielding assembly, secondary side shielding assembly; The primary shielding assembly and the secondary shielding assembly both comprise a coil (4), an integrated shielding plate (3), a heat sink (2) and an aluminum plate (1) which are arranged in sequence from the inside to the outside, and the primary shielding assembly and the secondary shielding assembly are symmetrically arranged; The integrated shielding plate (3) is composed of a composite of ferrite blocks and nanocrystalline strips, wherein: The ferrite blocks are distributed in a matrix arrangement in the area where the winding path of the coil (4) contacts the integrated shielding plate (3); The nanocrystalline strips are distributed on the integrated shielding plate (3) in an area other than the ferrite blocks, forming a double-row distributed nanocrystalline plate; The heat dissipation plate (2) is arranged between the integrated shielding plate (3) and the aluminum plate (1); The aluminum plate (1) is the outermost shielding structure.

2. A composite electromagnetic shielding mechanism for wireless power transmission according to claim 1, characterized in that: The integrated shielding plate (3) has a size of 400 mm×400 mm.

3. A composite electromagnetic shielding mechanism for wireless power transmission according to claim 1, characterized in that: The coil (4) is wound into a hollow square, the outer side length of the coil (4) is 300 mm, and the inner side length of the hollow square is 200 mm.

4. A composite electromagnetic shielding mechanism for wireless power transmission according to claim 1, characterized in that: The nanocrystalline ribbon has a width of 50 mm and a thickness of 18 um.

5. The composite electromagnetic shielding mechanism for wireless power transmission according to claim 1, characterized in that: The heat dissipation plate (2) is provided with heat dissipation holes.

6. A composite electromagnetic shielding mechanism for wireless power transmission according to claim 1, characterized in that: The integrated shielding plate (3) is fixed by gluing.

7. A composite electromagnetic shielding mechanism for wireless power transmission according to claim 1, characterized in that: The aluminum plate (1), the heat dissipation plate (2), and the integrated shielding plate (3) have the same size.

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