A wireless charging attachment, wireless power transmitting and receiving device

Abstract

The embodiment of the present invention discloses a wireless charging attachment device, a wireless power transmitting and receiving device, wherein the wireless charging attachment device comprises a first planar coil, a second planar coil and a connecting portion, wherein the first planar coil and the second planar coil respectively comprise a plurality of coil turns, and the connecting portion connects the lead-out ends of the first planar coil and the second planar coil, wherein the three are connected in series with each other, the first planar coil is arranged inside the second planar coil, and the current directions in the first planar coil and the second planar coil are opposite. The wireless power transmitting device and the wireless power receiving device are provided with a wireless charging attachment device. Therefore, the technical solution of the embodiment of the present invention can improve the efficiency of wireless charging and reduce losses by setting the winding method of the coil.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of wireless power, and in particular to a wireless charging attachment device, and a wireless power transmitting and receiving device. Background Art

[0002] Wireless charging technology can transmit power between electronic devices wirelessly, and is therefore widely used in consumer electronics and other types of electronic products. Wireless charging technology usually achieves wireless transmission of power through the mutual electromagnetic coupling of the transmitting coil and the receiving coil. The transmitting end converts the DC voltage into an alternating current, and the alternating current generates an alternating magnetic field through the transmitting coil. The receiving end couples the alternating magnetic field to induce a corresponding alternating voltage, and then converts the alternating voltage into a DC voltage through a rectifier circuit to charge the electronic device.

[0003] like Figure 1 As shown, in the prior art, in order to increase the magnetic field strength, a wireless charging attachment can be set between the wireless power transmitting coil and the wireless power receiving coil, and by connecting multiple turns of the coil in parallel, a magnetic field in the same direction as the wireless power transmitting coil is generated inside the coil, further improving the coupling between the wireless power receiving coil and the wireless power transmitting coil. However, if the number of parallel turns increases, the winding connecting the inner and outer circles in the circle area shown in the figure also needs to be increased accordingly, and this part of the area cannot provide an effective magnetic field. At the same time, the high-frequency alternating current flowing inside it will also cause additional losses. Summary of the invention

[0004] In view of this, an embodiment of the present invention provides a wireless charging attachment device, a wireless power transmitting and receiving device, which can improve the coil area utilization and improve the charging efficiency.

[0005] In a first aspect, a wireless charging attachment according to an embodiment of the present invention includes:

[0006] A first planar coil including a plurality of coil turns;

[0007] A second planar coil including a plurality of coil turns;

[0008] A connecting portion, connecting the lead-out ends of the first planar coil and the second planar coil;

[0009] The first planar coil, the second planar coil and the connecting portion are connected in series, the first planar coil is arranged inside the second planar coil, and the current directions in the first planar coil and the second planar coil are opposite.

[0010] Optionally, one or more compensation capacitors are connected in series or in parallel in the wireless charging attachment.

[0011] Optionally, the first planar coil and the second planar coil are arranged concentrically.

[0012] Optionally, the number of turns of the first planar coil is greater than the number of turns of the second planar coil.

[0013] Optionally, the spacing between coil turns of the first planar coil is a first spacing, the spacing between coil turns of the second planar coil is a second spacing, and the first spacing is different from the second spacing.

[0014] Optionally, the first spacing is smaller than the second spacing.

[0015] Optionally, the wireless charging attachment further includes a third planar coil, the third planar coil is arranged outside the second planar coil, and the current direction of the third planar coil is the same as that of the second planar coil;

[0016] The lead-out ends of the third planar coil are respectively connected to the lead-out ends of the first planar coil and the lead-out ends of the second planar coil through the connecting parts; or

[0017] The lead-out end of the third planar coil is connected to the lead-out end of the first planar coil through the connecting portion.

[0018] Optionally, the wireless charging attachment further includes a first magnetic sheet, wherein the first magnetic sheet has a hollow area, and a size of the hollow area is larger than a size of the first planar coil.

[0019] Optionally, the wireless charging attachment further includes a second magnetic sheet, which is disposed on another surface of the wireless charging attachment other than the surface on which the first magnetic sheet is disposed, and the second magnetic sheet has a size matching the first planar coil.

[0020] Optionally, the compensation capacitor is arranged at a position outside the first magnetic sheet and the second magnetic sheet.

[0021] Optionally, the wireless charging attachment is arranged on a circuit board, the circuit board has a via hole, and the first planar coil, the second planar coil and the connecting part are arranged on two sides of the circuit board through the via hole.

[0022] Optionally, the wireless charging attachment further comprises a shell, and the wireless charging attachment is arranged inside the shell.

[0023] In a second aspect, a wireless power transmitting device according to an embodiment of the present invention includes:

[0024] Wireless power transmitting coil;

[0025] The wireless charging attachment is arranged on a side of the wireless power transmitting coil facing the corresponding wireless power receiving coil and is separated from the wireless power transmitting coil by a predetermined distance.

[0026] In a third aspect, a wireless power receiving device according to an embodiment of the present invention includes:

[0027] Wireless power receiving coil;

[0028] The wireless charging attachment is arranged on a side of the wireless power receiving coil facing the corresponding wireless power transmitting coil and is separated from the wireless power receiving coil by a predetermined distance.

[0029] The wireless charging attachment device of the embodiment of the present invention includes a first planar coil, a second planar coil and a connecting portion, wherein the first planar coil and the second planar coil respectively include a plurality of coil turns, and the connecting portion connects the lead-out ends of the first planar coil and the second planar coil, wherein the three are connected in series with each other, the first planar coil is arranged inside the second planar coil, and the current directions in the first planar coil and the second planar coil are opposite. The wireless power transmitting device and the wireless power receiving device are provided with a wireless charging attachment device. Therefore, the technical solution of the embodiment of the present invention can improve the efficiency of wireless charging and reduce losses by setting the winding method of the coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other objects, features and advantages of the embodiments of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0031] Figure 1 It is a schematic diagram of the structure of a wireless charging attachment device in the prior art;

[0032] Figure 2 is a schematic diagram of a first embodiment of a wireless charging attachment according to an embodiment of the present invention;

[0033] Figure 3 is a schematic diagram of a second embodiment of a wireless charging attachment according to an embodiment of the present invention;

[0034] Figure 4 is a schematic diagram of a third embodiment of a wireless charging attachment according to an embodiment of the present invention;

[0035] Figure 5 is a schematic diagram of a fourth embodiment of a wireless charging attachment according to an embodiment of the present invention;

[0036] Figure 6 is a schematic diagram of a fifth embodiment of a wireless charging attachment according to an embodiment of the present invention;

[0037] Figure 7is a comparative schematic diagram of the sixth embodiment and the seventh embodiment of the wireless charging attachment device according to the embodiment of the present invention;

[0038] Figure 8 is a schematic diagram of an eighth embodiment of a wireless charging attachment according to an embodiment of the present invention;

[0039] Fig. 9 is a schematic diagram of a ninth embodiment of a wireless charging attachment according to an embodiment of the present invention;

[0040] Fig.10 is a schematic diagram of a wireless charging attachment according to an embodiment of the present invention being arranged on a circuit board;

[0041] Description of reference numerals:

[0042] 1-first planar coil; 2-second planar coil; 3-connecting portion; 4-third planar coil; 51-first magnetic sheet; 52-second magnetic sheet; 6-circuit board; 61-via; Cr-compensation capacitor;

[0043] X-first direction; Y-second direction. DETAILED DESCRIPTION

[0044] The present invention is described below based on embodiments, but the present invention is not limited to these embodiments. In the detailed description of the present invention below, some specific details are described in detail. It is possible for a person skilled in the art to fully understand the present invention without the description of these details. In order to avoid confusing the essence of the present invention, known methods, processes, flows, components and circuits are not described in detail.

[0045] In addition, persons of ordinary skill in the art will appreciate that the drawings provided herein are for illustration purposes and are not necessarily drawn to scale.

[0046] Unless the context clearly requires otherwise, the words "include", "comprising" and similar words throughout the application should be interpreted as including rather than exclusive or exhaustive; that is, the meaning is "including but not limited to".

[0047] In the description of the present invention, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0048] Unless otherwise clearly defined and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0049] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0050] Figure 2 Schematic diagram of the first embodiment of the wireless charging attachment of the present invention. Figure 2 As shown, the wireless charging attachment includes a first planar coil 1, a second planar coil 2 and a connecting portion 3. The first planar coil 1 and the second planar coil 2 respectively include a plurality of coil turns, and the connecting portion 3 connects the lead ends of the first planar coil 1 and the second planar coil 2. Among them, the first planar coil 1, the second planar coil 2 and the connecting portion 3 are connected in series with each other, the first planar coil 1 is arranged inside the second planar coil 2, and the current directions in the first planar coil 1 and the second planar coil 2 are opposite. In other words, the first planar coil 1 and the second planar coil 2 are formed into two independent coil groups, and the connecting portion 3 connects the lead ends of the two to each other, so as to form a closed loop, so that the current has different directions when flowing through the first planar coil 1 and the second planar coil 2.

[0051] Furthermore, the first planar coil 1 and the second planar coil 2 are arranged concentrically. According to the law of electromagnetic induction, when a magnetic field passes through a closed coil, an induced electromotive force will be generated inside the coil, thereby further generating a corresponding induced magnetic field according to the winding direction of the coil. In this embodiment, the first planar coil 1 and the second planar coil 2 are wound in opposite directions, and the connecting portion 3 respectively connects the outer lead end of the first planar coil 1 and the inner lead end of the second planar coil 2, and the inner lead end of the first planar coil 1 and the outer lead end of the second planar coil 2, so that the current flows through the first planar coil 1 along the first direction X, and flows through the second planar coil 2 along the second direction Y, wherein the first direction X is opposite to the second direction Y. Therefore, when an external magnetic field passes through the wireless charging attachment, an induced magnetic field corresponding to the direction of the internal induced current will be generated in the first planar coil 1 and the second planar coil 2. That is to say, during the use of the wireless charging attachment, it is placed between the wireless power transmitting coil and the wireless power receiving coil, so that the positions of the first planar coil 1 and the wireless power receiving coil correspond to each other, and the magnetic field directed from the wireless power transmitting coil to the wireless power receiving coil will pass through it, thereby generating an induced magnetic field in the first planar coil 1 and the second planar coil 2 in the same or opposite direction as the magnetic field.

[0052] At this time, if the induced magnetic field generated in the first planar coil 1 is in the same direction as the magnetic field emitted by the wireless power transmitting coil, the magnetic field received by the wireless power receiving coil can be enhanced, thereby improving the receiving efficiency of the wireless power receiving coil. In addition, an induced magnetic field in the opposite direction to the magnetic field emitted by the wireless power transmitting coil will be generated in the portion between the first planar coil 1 and the second planar coil 2, thereby reducing the eddy current loss caused by the magnetic field emitted by the wireless power transmitting coil acting on other metal materials, thereby further improving the transmission efficiency of wireless power.

[0053] Among them, the size of the first planar coil 1 should match the size of the wireless power receiving coil, that is, the first planar coil 1 should have a size similar to that of the wireless power receiving coil, so that when an induced magnetic field is generated in the same direction as the wireless power magnetic field, the wireless power receiving coil can have a better coupling degree.

[0054] Optionally, the first planar coil 1 and the second planar coil 2 can also be wound in the same direction. In this case, the connecting part 3 connects the inner lead end of the first planar coil 1 with the inner lead end of the second planar coil 2, and the outer lead end of the first planar coil 1 with the outer lead end of the second planar coil 2 respectively.

[0055] Figure 3 is a schematic diagram of a second embodiment of a wireless charging attachment according to an embodiment of the present invention. Figure 3As shown, one or more compensation capacitors Cr are connected in series or in parallel in the wireless charging attachment.

[0056] For the convenience of description, when the magnetic field directed from the wireless power transmitting coil to the wireless power receiving coil passes through it, the induced voltage generated in the first planar coil 1 is set to U1, and the induced voltage generated in the second planar coil 2 is set to U2, then the induced current generated in the coil can be obtained:

[0057]

[0058] Among them, L is the coil inductance and R is the coil impedance.

[0059] In order to further improve the transmission efficiency of wireless power, increasing the induced magnetic field generated in the first planar coil 1 and increasing the number of turns of the first planar coil 1 can be a feasible method. At this time, the induced voltage U1 increases accordingly, but the induced current I decreases. At the same time, if the number of turns of the second planar coil 2 is increased, although the difference between the induced voltage U2 and U1 can be increased, the increased impedance R still causes the induced current I to remain unchanged or decrease. Therefore, in this embodiment, the compensation capacitor Cr is connected in series in the loop formed, and the induced current I generated in the coil can be obtained:

[0060]

[0061] when When the induced current reaches the maximum, the induced magnetic field provided by the first planar coil 1 can be maximized. In other words, the compensation capacitor Cr can play a role in increasing the induced magnetic field in the circuit. In this embodiment, the compensation capacitor Cr is connected in series to the connecting portion 3. Optionally, the compensation capacitor Cr can also be set at any position of the coil.

[0062] Furthermore, the compensation capacitor Cr can adopt a method of connecting multiple capacitors in series to reduce the instantaneous voltage borne by a single capacitor, or adopt a method of connecting multiple small-capacitance capacitors in parallel to reduce capacitor losses, or adopt a method of connecting multiple capacitors in series and in parallel, which is not limited in the present application.

[0063] Figure 4 is a schematic diagram of a third embodiment of a wireless charging attachment according to an embodiment of the present invention. Figure 4 As shown, in order to enable the first planar coil 1 to provide more induced magnetic fields in the same direction as the magnetic field emitted by the wireless power transmitting coil and increase the coupling degree of the wireless power receiving coil, the number of turns of the first planar coil 1 should be greater than the number of turns of the second planar coil 2. For example, in this embodiment, the number of turns of the first planar coil 1 and the second planar coil 2 is changed, the number of turns of the first planar coil 1 is eight, and the number of turns of the second planar coil 2 is five. Optionally, it can also be set to other numbers of turns.

[0064] Furthermore, the spacing between the coil turns of the first planar coil 1 is a first spacing, and the spacing between the coil turns of the second planar coil 2 is a second spacing, and the first spacing is different from the second spacing. That is to say, the coil turns of the first planar coil 1 can be wound in a different tightness than the coil turns of the second planar coil 2, thereby changing the relationship between the induced current U of the coil and the impedance R inside the coil, and further changing the induced current I. In this embodiment, the first spacing is smaller than the second spacing, that is, the first planar coil 1 is tightly wound, while the second planar coil 2 is loosely wound. In this case, although the induced voltage U1 of the first planar coil 1 increases, and the induced voltage U2 of the second planar coil 2 decreases, the impedance R inside the coil can be reduced, thereby increasing the induced current I, so that a stronger induced magnetic field can be generated in the first planar coil 1.

[0065] Furthermore, the first spacings between the coil turns of the first planar coil 1 may be different from each other, and the second spacings between the coil turns of the second planar coil 2 may be different from each other, which is not limited in the present application.

[0066] Figure 5 2 is a schematic diagram of a fourth embodiment of a wireless charging attachment according to an embodiment of the present invention. Figure 6 is a schematic diagram of a fifth embodiment of a wireless charging attachment according to an embodiment of the present invention. Figure 5 as well as Figure 6 As shown, the coil turns of the first planar coil 1 and the second planar coil 2 may also have other arrangements.

[0067] In the fourth embodiment, the second planar coil 2 is wound with a wire having a larger diameter. In the fifth embodiment, the first planar coil 1 and the second planar coil 2 are wound with two strands connected in parallel. That is to say, the internal impedance R of the coil can be further reduced by increasing the wire diameter or connecting multiple strands of wire in parallel, thereby increasing the induced current I, so that the first planar coil 1 can provide a stronger induced magnetic field and improve the transmission efficiency of wireless power.

[0068] In the third embodiment, the fourth embodiment and the fifth embodiment, the winding pitch, the wire diameter and the parallel wires are changed to reduce the coil impedance R, thereby increasing the induced current I inside the coil. Optionally, the wireless charging attachment can also reduce the coil impedance R in other ways, thereby increasing the induced magnetic field in the first planar coil 1.

[0069] Figure 7 1 is a schematic diagram comparing the sixth embodiment and the seventh embodiment of the wireless charging attachment according to the present invention. Figure 7As shown, the wireless charging attachment further includes a third planar coil 4, which is arranged outside the second planar coil 2. That is to say, the third planar coil 4 has the same current direction as the second planar coil 2, and the induced current I flows through the third planar coil 4 along the second direction Y. Among them, the lead-out ends of the third planar coil 4 are respectively connected to the lead-out ends of the first planar coil 1 and the lead-out ends of the second planar coil 2 through the connecting portion 3, or are connected to the lead-out ends of the first planar coil 1 through the connecting portion 3. That is to say, the third planar coil 4 can be connected in series or in parallel with the second planar coil 2. In the case of series connection, the third planar coil 4 can provide a larger induced voltage U2; in the case of parallel connection, the third planar coil 4 can reduce the coil impedance R, thereby further increasing the induced current I.

[0070] In the sixth and seventh embodiments, the third planar coil 4 is formed as a three-turn coil outside the second planar coil 2 in the same winding direction as the second planar coil 2. Further, the spacing between the coil turns of the third planar coil 4 can be a third spacing, and the third spacing can be equal to or greater than the second spacing, and for the same reason as the second spacing, the third spacing should be greater than the first spacing. That is to say, the relationship between the three should be that the first spacing is less than the second spacing and less than or equal to the third spacing. In addition, the third spacings of the coil turns of the third planar coil 4 can also be different from each other.

[0071] Figure 8 is a schematic diagram of an eighth embodiment of a wireless charging attachment according to an embodiment of the present invention. Fig. 9 is a schematic diagram of a ninth embodiment of a wireless charging attachment according to an embodiment of the present invention. Figure 8 as well as Fig. 9 As shown, the wireless charging attachment may further include a magnetic sheet.

[0072] In the eighth embodiment, the wireless charging attachment includes a first magnetic sheet 51, the first magnetic sheet 51 has a hollow area, and the size of the hollow area is larger than the size of the first planar coil 1. That is to say, the first magnetic sheet 51 covers the second planar coil 2 and is configured to increase the induced voltage U2 of the second planar coil 2, thereby increasing the induced current I, so that a stronger induced magnetic field is generated in the first planar coil 1, and further shielding unnecessary interference. In this embodiment, the hollow area is formed into a circle matching the first planar coil 1, and optionally, the hollow area can also be designed into other shapes, such as an ellipse.

[0073] In the ninth embodiment, the wireless charging attachment device further includes a second magnetic sheet 52 in addition to the first magnetic sheet 51. The second magnetic sheet 52 is disposed below the first planar coil 1 and has a size matching that of the first planar coil 1. That is, the second planar coil 2 generates an induced voltage U2 in response to the magnetic field directed from the wireless power transmitting coil to the wireless power receiving coil. The first magnetic sheet 51 covered thereon has the effect of increasing the induced voltage U2. The corresponding induced current I further flows through the first planar coil 1, so that the induced voltage U1 is also generated in the first planar coil 1. The second magnetic sheet 52 below the first planar coil 1 has the effect of increasing the induced voltage U1, thereby enhancing the induced magnetic field in the first planar coil 1. Therefore, the second magnetic sheet 52 below the first planar coil 1 enables the wireless charging attachment device to better couple with the wireless power receiving coil, and the first magnetic sheet 51 covered on the second planar coil 2 enables the wireless charging attachment device to better couple with the wireless power transmitting coil.

[0074] Optionally, the material of the first magnetic sheet 51 and the second magnetic sheet 52 can be a common soft magnetic material, such as a nickel-zinc ferrite magnetic sheet and a manganese-zinc ferrite magnetic sheet, or an amorphous material and a nanocrystalline material.

[0075] Furthermore, in order to prevent the magnetic sheet from affecting the properties of the compensation capacitor Cr, when the compensation capacitor Cr is provided in the wireless charging attachment, the compensation capacitor Cr should be provided at a position other than the first magnetic sheet 51 and the second magnetic sheet 52. In other words, the compensation capacitor Cr should be provided in a hollow area of ​​the coil that does not pass through the first magnetic sheet 51 and the second magnetic sheet 52, or a local hollow area may be provided at other positions of the first magnetic sheet 51 and the second magnetic sheet 52 to place the compensation capacitor Cr. This design can reduce the thickness of the wireless charging attachment, making the product smaller and more usable.

[0076] In the sixth embodiment, the seventh embodiment, the eighth embodiment and the ninth embodiment, the manner of adding a third planar coil 4 connected in series or in parallel and adding a magnetic sheet are adopted respectively to increase the induced voltage U2 of the second planar coil 2, so that the induced current I inside the coil is increased. Optionally, the wireless charging attachment can also increase the induced voltage U2 by other means, thereby enhancing the induced magnetic field in the first planar coil 1.

[0077] Fig. 9 Schematic diagram of a wireless charging attachment according to an embodiment of the present invention disposed on a circuit board. Fig. 9As shown, the wireless charging attachment can be wound with copper wire or Litz wire or other similar wires to form a coil, or it can be arranged on the circuit board 6. In the case where the circuit board 6 has a via 61, the first planar coil 1, the second planar coil 2 and the connecting portion 3 can be arranged on both sides of the circuit board 6 through the via 61. That is to say, during the winding process of the coil, it can form a connected loop on the front and back sides of the circuit board 6 through the via 61 once or multiple times, thereby forming the first planar coil 1 and the second planar coil 2 on the front and back sides of the circuit board 6. Optionally, the via 61 can have a different arrangement from that of the present embodiment.

[0078] Furthermore, the wireless charging attachment also includes a shell, and the wireless charging attachment is arranged inside the shell. In this embodiment, the shell is a mobile phone shell. That is to say, in actual application scenarios, the wireless charging attachment is arranged inside the mobile phone shell. When the mobile phone shell is installed on the mobile phone, when the mobile phone is wirelessly charged in conjunction with an external wireless power transmitting coil, the wireless charging attachment is located between the wireless power transmitting coil and the wireless power receiving coil in the mobile phone, which can increase the coupling degree of the wireless power receiving coil of the mobile phone and improve the charging efficiency. This design makes the wireless charging attachment have good usability, easy to carry and convenient to use. Optionally, the shell can also be a protective shell for other products with wireless power transmitting coils arranged inside.

[0079] Furthermore, the wireless charging attachment can be used as a product alone, or it can be configured in other wireless power equipment as a component to improve the transmission efficiency of wireless power. For example, it can be applied to a wireless power transmitting device including a wireless power transmitting coil, and is arranged on the side of the wireless power transmitting coil facing the corresponding wireless power receiving coil, and is separated from the wireless power transmitting coil by a predetermined distance. Alternatively, it can be arranged in a wireless power receiving device including a wireless power receiving coil, and is arranged on the side of the wireless power receiving coil facing the corresponding wireless power transmitting coil, and is separated from the wireless power receiving coil by a predetermined distance. Or in other wireless power systems, the present application is not limited here.

[0080] The wireless charging attachment device of the embodiment of the present invention includes a first planar coil, a second planar coil and a connecting portion, wherein the first planar coil and the second planar coil respectively include a plurality of coil turns, and the connecting portion connects the lead-out ends of the first planar coil and the second planar coil, wherein the three are connected in series with each other, the first planar coil is arranged inside the second planar coil, and the current directions in the first planar coil and the second planar coil are opposite. The wireless power transmitting device and the wireless power receiving device are provided with a wireless charging attachment device. Therefore, the technical solution of the embodiment of the present invention can improve the efficiency of wireless charging and reduce losses by setting the winding method of the coil.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A wireless charging attachment, characterized in that: include: A first planar coil (1) comprising a plurality of coil turns; A second planar coil (2) comprising a plurality of coil turns; A connecting portion (3) connecting the lead-out ends of the first planar coil (1) and the second planar coil (2); The first planar coil (1), the second planar coil (2) and the connecting portion (3) are connected in series, the first planar coil (1) is arranged inside the second planar coil (2), and the current directions in the first planar coil (1) and the second planar coil (2) are opposite; The wireless charging attachment further comprises a third planar coil (4), the third planar coil (4) being arranged outside the second planar coil (2), and the current direction of the third planar coil (4) and the second planar coil (2) being the same; The lead-out end of the third planar coil (4) is connected to the lead-out end of the first planar coil (1) via the connecting portion (3).

2. The wireless charging attachment according to claim 1, characterized in that: One or more compensation capacitors are connected in series or in parallel in the wireless charging attachment.

3. The wireless charging attachment according to claim 1, characterized in that: The first planar coil (1) and the second planar coil (2) are arranged concentrically.

4. The wireless charging attachment according to claim 1, characterized in that: The number of turns of the first planar coil (1) is greater than the number of turns of the second planar coil (2).

5. The wireless charging attachment according to claim 1, characterized in that: The spacing between coil turns of the first planar coil (1) is a first spacing, and the spacing between coil turns of the second planar coil (2) is a second spacing, and the first spacing is different from the second spacing.

6. The wireless charging attachment according to claim 5, characterized in that: The first spacing is smaller than the second spacing.

7. The wireless charging attachment according to claim 2, characterized in that: The wireless charging attachment further comprises a first magnetic sheet (51), wherein the first magnetic sheet (51) has a hollow area, and the size of the hollow area is greater than the size of the first planar coil (1).

8. The wireless charging attachment according to claim 7, characterized in that: The wireless charging attachment further comprises a second magnetic sheet (52), the second magnetic sheet (52) being arranged on the other side of the wireless charging attachment other than the side on which the first magnetic sheet (51) is arranged, and the second magnetic sheet (52) has a size matching that of the first planar coil (1).

9. The wireless charging attachment according to claim 8, characterized in that: The compensation capacitor is arranged at a position outside the first magnetic sheet (51) and the second magnetic sheet (52).

10. The wireless charging attachment according to claim 1, characterized in that: The wireless charging attachment is arranged on a circuit board (6), the circuit board (6) has a via hole (61), and the first planar coil (1), the second planar coil (2) and the connecting portion (3) are arranged on two sides of the circuit board through the via hole (61).

11. The wireless charging attachment according to claim 1, characterized in that: The wireless charging attachment also includes a shell, and the wireless charging attachment is arranged inside the shell.

12. A wireless power transmitting device, characterized in that: include: Wireless power transmitting coil; The wireless charging attachment according to any one of claims 1 to 11 is arranged on a side of the wireless power transmitting coil facing the corresponding wireless power receiving coil and is separated from the wireless power transmitting coil by a predetermined distance.

13. A wireless power receiving device, characterized in that: include: Wireless power receiving coil; The wireless charging attachment according to any one of claims 1 to 11 is arranged on a side of the wireless power receiving coil facing the corresponding wireless power transmitting coil and is separated from the wireless power receiving coil by a predetermined distance.

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