Magnetic attraction positioning magnetic sheet and wireless charging module

Abstract

The present invention belongs to the technical field of wireless charging, and discloses a magnetic attraction positioning magnetic sheet and a wireless charging module. The magnetic attraction positioning magnetic sheet comprises hard magnetic material sheets and soft magnetic material sheets, wherein the hard magnetic material sheets and the soft magnetic material sheets are arranged in an alternating manner to form an annular positioning magnetic sheet. The hard magnetic material sheets may be selected as magnet sheets (e.g., samarium-cobalt magnet sheets, neodymium-iron-boron magnet sheets, ferrite magnet sheets, aluminum-nickel-cobalt magnet sheets and iron-chromium-cobalt magnet sheets); and the soft magnetic material sheets are at least one of amorphous and / or nanocrystalline magnetic sheets, soft magnetic ferrite sheets and soft magnetic alloy sheets. The magnetic attraction positioning magnetic sheet of the present invention can weaken or even completely avoid the interference of the magnetic attraction positioning magnetic sheet on a WPC coil while ensuring the magnetic attraction alignment between a receiver and a transmitter, thereby reducing loss and improving the charging efficiency. In addition, the magnetic attraction positioning magnetic sheet has a lower cost, and the structure and assembly thereof are more convenient, thereby facilitating the popularization of magnetic attraction.

Description

A magnetic positioning magnetic sheet and a wireless charging module Technical Field

[0001] This invention belongs to the field of wireless charging technology, specifically relating to a magnetic positioning sheet and a wireless charging module. Background Technology

[0002] Wireless charging is now a standard feature on high-end flagship phones. The convenience of charging without cables—simply place the phone on the ground to charge—has made this feature increasingly popular. Driven by domestic Chinese phone brands, wireless charging speeds can now reach up to 100W, surpassing the wired charging speeds of many phones.

[0003] Currently, there is an increasing variety of supporting products such as wireless power banks, wireless charging docks, and wireless car chargers. Meanwhile, the ecosystem of mobile phone peripherals that support wireless charging, such as TWS Bluetooth earphones, smartwatches, and smart bracelets, is becoming more and more complete. There is no doubt that wireless charging technology will be further developed and popularized.

[0004] The main technical indicators for wireless charging of consumer electronics are threefold: charging power, efficiency, and heat generation (temperature rise). A common problem when wirelessly charging consumer electronics is misalignment. In this case, wireless charging efficiency and power decrease significantly, and heat generation becomes severe. This is because: severe misalignment causes a large number of magnetic lines of force at the transmitting end to fail to effectively pass through the receiving coil, resulting in low charging efficiency; simultaneously, misalignment causes a large number of magnetic lines of force to pass through a localized (non-central) area of ​​the coil, causing an excessively strong magnetic field in that area or even saturation, leading to a sharp increase in losses, insufficient heat dissipation, and a high temperature rise.

[0005] The low charging efficiency and severe overheating caused by severe misalignment can be addressed by increasing the size and thickness of the charging pad, adding a cooling fan, or reducing the charging power, but these methods incur higher costs or extend charging time. Therefore, a better solution is to ensure proper alignment and fundamentally avoid the misalignment problem. Apple, a leading mobile phone manufacturer, has introduced magnetic wireless charging, which uses ring-shaped magnets at both the transmitter and receiver ends to ensure precise coil alignment through magnetic attraction. With the Wireless Power Consortium (WPC) officially announcing the new wireless charging standard—Qi 2.0—in 2022, which incorporates Apple's MagSafe magnetic charging protocol, magnetic wireless charging is poised for further widespread adoption.

[0006] However, the presence of the magnet also introduces new problems. First, the magnet has an impact on the coil module's saturation current. When the magnet's magnetic field direction is the same as the coil's magnetic field direction, a false increase in saturation current may occur. The size of the additional bias current that reduces the inductance of the coil to a certain proportion is the saturation current. If the magnetic field generated by the coil's additional bias current and the magnet's magnetic field are in the same direction, the nanocrystalline magnetic lines will cancel each other out, resulting in an increase in the coil module's saturation current (as shown in Figures 1 and 2). If the magnetic field generated by the coil's additional bias current and the magnet's magnetic field are in opposite directions, the nanocrystalline is more likely to be saturated, resulting in a decrease in the coil module's saturation current (as shown in Figures 3 and 4). That is, the presence of the magnet is equivalent to the coil being pre-charged with an additional constant bias current. Second, the magnets used in magnetic attraction are generally ferromagnetic alloys such as neodymium iron boron or Fe3O4, which are prone to eddy current loss in an alternating magnetic field. The magnet should be at a sufficient distance from the coil. However, the space for consumer electronics wireless charging is often limited, which often brings the magnet and the coil closer together, causing the magnet to consume part of the energy and reducing the efficiency of wireless charging. Therefore, the problems introduced by the magnet in the magnetic attraction type wireless charging need to be solved.

[0007] Patent CN 202110665207.0 discloses a wireless charging magnetic positioning structure, which includes a first magnet and a second magnet; the first magnet and the second magnet are arranged alternately around the wireless charging coil to form a ring shape; and the magnetization directions of the first magnet and the second magnet are opposite. By arranging the first magnet and the second magnet alternately around the wireless charging coil to form a ring shape, and making the magnetization directions of the first magnet and the second magnet opposite, the first magnet of the transmitting end and the first magnet of the receiving end, and the second magnet of the transmitting end and the second magnet of the receiving end form a closed loop of magnetic lines of force, thereby improving the magnetic attraction force between the transmitting end and the receiving end. The magnetization directions of the adjacent first magnet and second magnet are opposite, so that the magnetic attraction force generated by the magnets of the transmitting end and the receiving end is greater, and the influence of the magnetic lines of force on the module is smaller. However, this structure requires a large number of magnetized small magnets, which is complex to assemble, and a large gap between the magnets and the magnetic shielding sheet is required, thereby reducing the interference of the closed loop magnetic lines of force formed between the first magnet and the second magnet on the magnetic flux of the wireless charging coil.

[0008] In our previous patent CN 202310740011.2, by arranging nanocrystalline layer magnetic shielding strips perpendicular to the plane of the ring-shaped positioning magnet on the inner side and the outer side of the ring-shaped positioning magnet, the interference of the magnetic attraction positioning magnetic sheet on the coil can be shielded or weakened, the loss is reduced, and the charging efficiency is improved. However, the arrangement of the magnetic shielding strips still increases the structure and assembly complexity of the wireless charging module to some extent.

[0009] SUMMARY

[0010] In view of the defects and shortcomings of the prior art, the primary object of the present application is to provide a magnetic positioning magnetic sheet. The magnetic positioning magnetic sheet can ensure that the receiving end and the transmitting end are magnetically attracted and positioned at the same time, and can weaken or even completely avoid the interference of the magnetic positioning magnetic sheet on the WPC coil, reduce the loss and improve the charging efficiency. In addition, the scheme has lower cost, more convenient structure and assembly, and is conducive to the popularization and promotion of magnetic attraction.

[0011] Another object of the present application is to provide a wireless charging module comprising the above-mentioned magnetic positioning magnetic sheet.

[0012] The object of the present application is achieved by the following technical solutions:

[0013] A magnetic positioning magnetic sheet comprises a hard magnetic material sheet and a soft magnetic material sheet, and the hard magnetic material sheet and the soft magnetic material sheet are arranged in a spaced manner to form a ring-shaped positioning magnetic sheet.

[0014] Preferably, the hard magnetic material sheet is a magnet sheet (such as a samarium-cobalt magnet sheet, a neodymium-iron-boron magnet sheet, a ferrite magnet sheet, an aluminum-nickel-cobalt magnet sheet, an iron-chromium-cobalt magnet sheet, etc.); and the soft magnetic material sheet is at least one of an amorphous and / or nanocrystalline magnetic sheet, a soft magnetic ferrite magnetic sheet, and a soft magnetic alloy sheet.

[0015] Preferably, the number of hard magnetic material sheets is greater than or equal to 2, and the number of soft magnetic material sheets is greater than or equal to 2; and the soft magnetic material sheets are arranged symmetrically based on the center of the ring-shaped positioning magnetic sheet. By symmetrically arranging the soft magnetic material sheets to replace part of the hard magnetic material sheets, the interference of the magnet on the coil module is reduced, and the loss is reduced.

[0016] Further preferably, the vertical projection area ratio of the soft magnetic material sheet in the ring-shaped positioning magnetic sheet is 10% to 90%. In the present application, the hard magnetic material sheet has low magnetic permeability and high coercive force, can maintain magnetism for a long time after magnetization, and can ensure good magnetic positioning capability; the soft magnetic material sheet has low coercive force and high magnetic permeability characteristics, can be magnetized by adjacent magnet sheets to generate magnetic force, ensure magnetic positioning capability, and can attract the magnetic force lines of the magnet sheet, reduce the interference of the magnet sheet on the WPC coil, and the soft magnetic material sheet has lower hysteresis loss and eddy current loss due to its high magnetic permeability characteristics. Compared with a conventional ring-shaped magnetic positioning magnet sheet (structure schematic diagram as shown in FIG. 5), the wireless charging efficiency can be improved to a certain extent while ensuring good magnetic positioning capability.

[0017] Preferably, the thickness of the hard magnetic material sheet and the soft magnetic material sheet is 0.2 to 1.0 mm, and the thickness of the hard magnetic material sheet and the soft magnetic material sheet is the same.

[0018] Further preferably, the soft magnetic material sheet is an amorphous and / or nanocrystalline magnetic sheet.

[0019] Further preferably, the non-crystalline and / or nanocrystalline magnetic sheet is composed of multiple layers of non-crystalline and / or nanocrystalline material layers pasted together by double-sided adhesive film or bonding resin. It can be obtained by punching processing of multiple layers of non-crystalline and / or nanocrystalline strips pasted by double-sided adhesive or cured by bonding resin impregnation.

[0020] Further preferably, the single layer thickness of the non-crystalline and / or nanocrystalline material layer is 5-35 μm.

[0021] Further preferably, the non-crystalline and / or nanocrystalline material layer is non-crystalline and / or nanocrystalline with a composition system of FeSiB, FeSiBC, FeCoSiBPC, FeCuNbSiB, FeCuMoSiB, FeSiBPCu.

[0022] Further preferably, the relative magnetic permeability of the non-crystalline and / or nanocrystalline magnetic sheet is 100-10000. If the magnetic permeability is too low, the magnetic attraction of the magnetic sheet may be insufficient, reducing the improvement effect; if the magnetic permeability is too high, the magnetic field of the WPC coil is easily attracted, causing loss.

[0023] Further preferably, a layer of annular non-crystalline and / or nanocrystalline magnetic shielding sheet is further provided below the annular positioning magnetic sheet to serve as a carrier and shield the magnetic field.

[0024] Further preferably, the thickness of the annular non-crystalline and / or nanocrystalline magnetic shielding sheet is 0.02-0.1 mm, and the width is 0-0.5 mm wider than the annular positioning magnetic sheet.

[0025] A wireless charging module comprising the above-mentioned magnetic attraction positioning magnetic sheet, comprising a magnetic shielding sheet, a coil provided on the magnetic shielding sheet, and a magnetic attraction positioning magnetic sheet, wherein the magnetic attraction positioning magnetic sheet surrounds the periphery of the magnetic shielding sheet and the coil.

[0026] Compared with the prior art, the present application has the following advantages:

[0027] (1) Compared with the prior art annular magnetic positioning magnetic sheet, the soft magnetic material sheet with low coercivity and high magnetic permeability is used to replace the magnetic sheet, which can be magnetized by the adjacent magnetic sheet to generate magnetic force, ensuring the magnetic attraction positioning capability, and can attract the magnetic field lines of the magnetic sheet, reducing the interference of the magnetic sheet on the WPC coil. At the same time, the soft magnetic material sheet has lower hysteresis loss and eddy current loss due to its high magnetic permeability, which can reduce the loss and improve the wireless charging efficiency while ensuring good magnetic attraction positioning capability.

[0028] (2) The soft magnetic material sheet used in the positioning magnetic sheet of the present application does not need to be magnetized, and the number of small magnetic sheets used to form the annular positioning magnetic sheet can be smaller, and the assembly is more convenient.

[0029] (3) Increase the receiving end compatibility, due to less hard magnetic material, regardless of the transmitting end has no magnetic function, more easily through the wireless charging work before the foreign object detection. BRIEF DESCRIPTION OF DRAWINGS

[0030] Fig. 1 and Fig. 2 are schematic diagrams of magnetic induction lines of the same direction of the magnetic field of the coil plus bias current and the magnetic field of the magnetic positioning magnet in the magnetic type wireless charging module.

[0031] Fig. 3 and Fig. 4 are schematic diagrams of magnetic induction lines of the opposite direction of the magnetic field of the coil plus bias current and the magnetic field of the magnetic positioning magnet in the magnetic type wireless charging module.

[0032] Fig. 5 is a schematic diagram of the structure of a conventional annular magnetic positioning magnet sheet.

[0033] Fig. 6 is a schematic diagram of the structure of a magnetic positioning magnet sheet in Example 1.

[0034] Fig. 7 is a schematic diagram of the structure of a magnetic positioning magnet sheet in Example 2.

[0035] Fig. 8 is a schematic diagram of the structure of a magnetic positioning magnet sheet in Example 3.

[0036] Fig. 9 and Fig. 10 are schematic diagrams of the overall structure and the cross-sectional view of A of a magnetic type wireless charging module in Example 5.

[0037] Fig. 11 is a schematic diagram of the structure of a magnetic positioning magnet sheet in Comparative Example 2. DETAILED DESCRIPTION

[0038] The application will be further described in conjunction with the embodiments and the accompanying drawings, but the embodiments of the application are not limited thereto.

[0039] Example 1

[0040] A magnetic positioning magnet sheet, the schematic diagram of the structure of which is shown in Fig. 6. It comprises a neodymium iron boron magnet sheet 3-1 and a FeCuNbSiB nanocrystalline sheet 3-2, and the magnet sheet 3-1 and the nanocrystalline sheet 3-2 are arranged in a spaced manner to form an annular positioning magnet sheet. The thickness of the magnet sheet 3-1 and the nanocrystalline sheet 3-2 is 0.3 mm; the size of the magnet sheet 3-1 and the nanocrystalline sheet 3-2 is the same, and they are arranged in a spaced manner in an alternating form of one magnet sheet and one nanocrystalline sheet.

[0041] The nanocrystalline sheet is prepared by the following method:

[0042] The nanocrystalline strip with a single layer thickness of 18-20 μm is selected, a first glue layer is formed on the upper surface of the uppermost nanocrystalline strip, a second glue layer is formed on the lower surface of the lowermost nanocrystalline strip, and a third glue layer is formed between adjacent nanocrystalline strips to cover the magnetic single-layer structure containing two layers of nanocrystals, so that the initial permeability of the magnetic single-layer structure is 1000 at a test frequency of 100 kHz according to the total thickness of the nanocrystals after fragmentation treatment. The magnetic single-layer structure is stacked multiple times to obtain a magnetic composite layer structure with a total thickness of about 0.3 mm. Then it is punched into a design shape and combined with a small magnet piece.

[0043] Example 2

[0044] A magnetic positioning magnetic sheet, the structural schematic diagram of which is shown in Figure 7. It comprises samarium-cobalt magnetic pieces 3-1 and FeCuNbSiB nanocrystalline pieces 3-2, which are arranged in a ring-shaped positioning magnetic sheet. The thickness of the magnetic pieces 3-1 and the nanocrystalline pieces 3-2 is 0.4 mm; the size of the nanocrystalline pieces 3-2 is the same as that of two magnetic pieces 3-1, and they are arranged in an alternating form of two magnetic pieces and one nanocrystalline piece.

[0045] Example 3

[0046] A magnetic positioning magnetic sheet, the structural schematic diagram of which is shown in Figure 8. It comprises neodymium-iron-boron magnetic pieces 3-1 and FeSiB amorphous pieces 3-2, which are arranged in a ring-shaped positioning magnetic sheet. The thickness of the magnetic pieces 3-1 and the nanocrystalline pieces 3-2 is 0.5 mm. The nanocrystalline pieces are combined in different sizes, wherein the size of the large nanocrystalline piece is the same as that of two magnetic pieces; the size of the small nanocrystalline piece is the same as that of one magnetic piece; and they are arranged in an alternating form of one magnetic piece, one small nanocrystalline piece, one magnetic piece and one large nanocrystalline piece.

[0047] Example 4

[0048] A magnetic positioning magnetic sheet, compared with Example 1, a ring-shaped nanocrystalline magnetic separation piece is further arranged below the ring-shaped positioning magnetic sheet to play a role of bearing and shielding the magnetic field. The thickness of the ring-shaped nanocrystalline magnetic separation piece is 0.05 mm, and the width is 0.2 mm wider than that of the ring-shaped positioning magnetic piece.

[0049] Example 5

[0050] A magnetic wireless charging module, the overall structure schematic diagram and A cross-sectional schematic diagram are shown in Figures 9 and 10 respectively. It includes a magnetic separation sheet 1, a coil 2 arranged on the magnetic separation sheet, and a magnetic positioning magnetic sheet, which surrounds the periphery of the magnetic separation sheet 1 and the coil 2. The magnetic positioning magnetic sheet adopts the magnetic positioning magnetic sheet of embodiment 4, which is composed of an annular positioning magnetic sheet 3 and a nanocrystalline magnetic separation sheet 4 below.

[0051] Comparative example 1

[0052] A magnetic positioning magnetic sheet, compared with embodiment 1, the annular positioning magnetic sheet is replaced by a conventional annular magnetic positioning magnet sheet (structure schematic diagram as shown in Figure 5), and the rest is the same.

[0053] Comparative example 2

[0054] A magnetic positioning magnetic sheet, the structure schematic diagram is shown in Figure 11. Compared with embodiment 1, the nanocrystalline sheet in the annular positioning magnetic sheet is cancelled, and only the magnetic sheet 3-1 part is reserved.

[0055] The test effect comparison of different embodiments is shown in Table 1 below. After replacing part of the magnet with amorphous nanocrystalline, the positioning magnetic force size and the maximum horizontal correction displacement are similar to those of comparative example 1, and the charging efficiency η is equal or slightly improved, which shows that it is feasible to replace part of the magnet with amorphous nanocrystalline in function. Compared with the assembly efficiency and cost, embodiments 1-4 have significant advantages over comparative examples.

[0056] Table 1 Comparison of test effects of different embodiments Note: The above test transmitting end is a market mainstream magnetic wireless charger, and the receiving end is a certain model of iPhone charging module supporting magnetic wireless charging and its embodiment magnet replacement improvement;

[0057] *The positioning magnetic force size: after the transmitting end and the receiving end magnet are positioned and attached, the minimum force required for the two to vertically separate along the magnetic ring center axis, the greater the force, the stronger the magnetic positioning attraction force;

[0058] **The maximum horizontal correction displacement: after the transmitting end and the receiving end magnet are positioned and attached, the transmitting end (about 100g) moves horizontally perpendicular to its magnetic ring center axis, and the minimum displacement after the transmitting end cannot automatically reset, the greater the value, the stronger the magnetic positioning correction ability;

[0059] ***Charging efficiency η: η = receiving end power / transmitting end power × 100%, the higher the η, the smaller the charging loss.

[0060] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications, etc. made without departing from the spirit and principles of the present application should be equivalent replacement manners and should be included in the protection scope of the present application.

Claims

1. A magnetic positioning magnetic sheet, characterized by, The annular positioning magnetic sheet comprises hard magnetic material sheets and soft magnetic material sheets, which are arranged at intervals.

2. The magnetic positioning magnetic sheet according to claim 1, wherein, The hard magnetic material sheets are magnet sheets; the soft magnetic material sheets are at least one of amorphous and / or nanocrystalline magnetic sheets, soft magnetic ferrite magnetic sheets and soft magnetic alloy sheets.

3. The magnetic positioning magnetic sheet according to claim 1, wherein, The number of the hard magnetic material sheets is greater than or equal to 2, and the number of the soft magnetic material sheets is greater than or equal to 2; the soft magnetic material sheets are arranged symmetrically based on the center of the annular positioning magnetic sheet.

4. The magnetic positioning magnetic sheet according to claim 1, wherein, The area ratio of the vertical projection of the soft magnetic material sheet in the annular positioning magnetic sheet is 10% to 90%.

5. The magnetic positioning magnetic sheet according to claim 1, wherein, The thickness of the hard magnetic material sheet and the soft magnetic material sheet is 0.2 to 1.0 mm, and the thickness of the hard magnetic material sheet and the soft magnetic material sheet is the same.

6. The magnetic positioning magnetic sheet of claim 1, wherein, The soft magnetic material sheet is an amorphous and / or nanocrystalline magnetic sheet.

7. The magnetic positioning magnetic sheet according to claim 6, characterized in that, The amorphous and / or nanocrystalline magnetic sheet is composed of multiple layers of amorphous and / or nanocrystalline material layers pasted and combined by double-sided adhesive film or adhesive resin.

8. The magnetic positioning magnetic sheet according to claim 7, characterized in that, The thickness of the single layer of the amorphous and / or nanocrystalline material layer is 5 to 35 μm.

9. The magnetic positioning magnetic sheet of claim 7, wherein, The amorphous and / or nanocrystalline material layer is amorphous and / or nanocrystalline with a composition system of FeSiB, FeSiBC, FeCoSiBPC, FeCuNbSiB, FeCuMoSiB and FeSiBPCu.

10. The magnetic positioning magnetic sheet of claim 6, wherein, The relative magnetic permeability of the amorphous and / or nanocrystalline magnetic sheet is 100 to 10,000.

11. The magnetic positioning magnetic sheet according to claim 1, characterized in that, A layer of annular amorphous and / or nanocrystalline magnetic sheet is further arranged below the annular positioning magnetic sheet to bear and shield the magnetic field.

12. The magnetic positioning magnetic sheet of claim 11, wherein, The thickness of the annular amorphous and / or nanocrystalline magnetic sheet is 0.02 to 0.1 mm, and the width is 0 to 0.5 mm wider than the annular positioning magnetic sheet.

13. A wireless charging module comprising the magnetic positioning magnetic sheet of any one of claims 1-12. The magnetic attraction positioning magnetic sheet of any one of claims 1 to 12 is arranged around the periphery of the magnetic sheet and the coil.

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