Cross coil for wireless power transmission

Abstract

The invention discloses a cross-shaped coil for wireless power transmission, belongs to the technical field of cross-shaped coils, and can adjust the values and the number of compensation capacitors and inductors for impedance matching according to actual needs, flexibly adjust the working frequency of the coil or optimize the performance of the coil. The purpose of being suitable for each frequency band or improving the transmission efficiency is achieved without redesigning a new receiving and transmitting coil. The shapes of the transmitting coil and the receiving coil can be modified to a certain extent according to actual requirements or aesthetic requirements. Materials used by the coil are all the most common materials, and high power transmission efficiency can be achieved with lower cost.

Description

Technical Field

[0001] The invention relates to a cross-shaped coil, in particular to a cross-shaped coil used for wireless power transmission, and belongs to the technical field of cross-shaped coils. Background Art

[0002] In order to achieve high-efficiency transmission, most studies choose to use a coupler structure with multiple orthogonal coils.

[0003] Dai's team studied a WPT system in which both the transmitter and receiver are three-dimensional structures, a regular tetrahedron receiver, which has good power receiving capability and relatively high system efficiency at any angle.

[0004] Tianjin University proposed a coil with an orthogonal topology structure, which is a new structure assembled from three vertical coils to compensate for the huge fluctuations in power transmission and realize an omnidirectional wireless charging system that is insensitive to angle misalignment.

[0005] The University of Hong Kong proposed and implemented a new wireless power and drive transmission system using orthogonal bipolar coupler and split excitation modulation.

[0006] Specifically, the two bipolar coils are orthogonally integrated and naturally decoupled to form a compact magnetic coupler for transmitter and receiver respectively.

[0007] It can be achieved that the system transmission efficiency reaches 89.5% when the resistance load is 40Ω and the transmission distance is 100mm.

[0008] The magnetic structure in the prior art includes a target-shaped transmitter and two orthogonal receivers, and the transmitter consists of four toroidal coils magnetized in a bipolar mode so that a magnetic field with complementary distribution of parallel and perpendicular magnetic fluxes can be formed. Then, by integrating two orthogonal receiving coils into one receiver, only a small-sized receiver is required to provide a stable total output current for the drone's onboard load.

[0009] In wireless power transmission systems, the use of a two-dimensional coupling structure will result in a limited anti-offset capability. However, in actual applications, the transmitting coil and the receiving coil cannot be perfectly aligned without the help of external forces, and there will be a problem of offset in spatial position, resulting in a rapid decrease in transmission efficiency. In existing studies, in order to solve the problem of decreased efficiency, the two-dimensional coil is optimized, including optimizing the coil line width, line spacing, number of turns, or using multiple coils for stacking. Although this method improves the anti-offset effect of the two-dimensional coil to a certain extent, whether increasing the coil structure or using multiple coils will use more materials and increase the size or cost, and may also increase the complexity of the system. For this reason, a cross coil for wireless power transmission is designed to solve the above problems. Summary of the invention

[0010] The main object of the present invention is to provide a cross coil for wireless power transmission.

[0011] The purpose of the present invention can be achieved by adopting the following technical solutions:

[0012] A cross-shaped coil for wireless power transmission, comprising a first transmitting coil and a second transmitting coil;

[0013] The first transmitting coil and the second transmitting coil are orthogonally connected, and the first transmitting coil and the second transmitting coil are connected in series;

[0014] Each turn of the first transmitting coil and the second transmitting coil are crossed at equal intervals to form orthogonality.

[0015] Preferably, the first transmitting coil is mounted on the first substrate, the second transmitting coil is mounted on the second substrate, and a second slot penetrated by the first transmitting coil is provided on the second substrate;

[0016] A third slot is also provided on the second substrate.

[0017] Preferably, the first transmitting coil and the first substrate are formed by clamping an upper disassembled coil group and a lower disassembled coil group;

[0018] The upper disassembled coil assembly passes through the second slot and the third slot and is clamped with the lower disassembled coil assembly through the first clamping assembly and the second clamping assembly.

[0019] Preferably, the upper disassembled coil assembly comprises an upper transmitting coil, an upper substrate and a first slot;

[0020] An upper transmitting coil is installed on the top of the upper substrate, and a first slot for accommodating a second transmitting coil is opened on one side of the upper substrate. The upper transmitting coil passes through the second slot and is clamped with the lower disassembled coil group.

[0021] Preferably, the lower disassembled coil assembly includes a lower transmitting coil and a lower substrate;

[0022] A lower transmitting coil is installed on the top of the lower substrate, and the cross sections of the upper transmitting coil and the lower transmitting coil are in contact and fit with each other.

[0023] Preferably, the first clamping group includes a clamping slot, an L-shaped clamping piece, a first side limiting groove, a second side limiting groove, a first conical clamping piece, and a second conical clamping piece;

[0024] Card slots are installed on both sides of the end of the upper transmitting coil, and L-shaped clamps that are inserted into the card slots are installed on the ends of both sides of the lower transmitting coil. Second side limiting grooves are opened on both sides of the L-shaped clamp and a first conical clamp is installed. The inner side of the card slot is opened with a first side limiting groove and a second conical clamp is installed.

[0025] Preferably, the second clamping assembly includes a plug, a side plug, a built-in slot, a built-in spring, a through inner hole and an arc-shaped clamp;

[0026] A plug is installed on the top edge of the upper base plate, and a side plug-in is installed on the top edge of the lower base plate. A through inner hole is opened on the inner end of the plug, and a built-in groove is opened on the inner side of the side plug-in. A built-in spring is installed on the inner wall of the built-in groove, and an arc-shaped clip is installed on the outer end of the built-in spring. The arc-shaped clip is inserted into the through inner hole and cooperates with the plug.

[0027] Preferably, the first transmitting coil and the second transmitting coil cooperate orthogonally and cooperate with the receiving coil;

[0028] The receiving coil is placed between the first transmitting coil and the second transmitting coil at an angle of 45° to the first transmitting coil and the second transmitting coil.

[0029] Beneficial technical effects of the present invention:

[0030] The cross-shaped coil for wireless power transmission provided by the present invention can generate a wider and more uniform magnetic field in both the XOY plane and the YOZ plane compared with the traditional two-dimensional coil.

[0031] From the perspective of the three-dimensional coil as a whole, the magnetic field distribution range after the magnetic fields generated by the two planes are synthesized can cover a larger space, achieving good all-round (horizontal direction, vertical direction, angular rotation) anti-offset performance independent of the position of the receiving coil.

[0032] The coil structure of the present invention is a three-dimensional coil structure formed by fully utilizing the space where the coil is located on the basis of the two-dimensional coil structure, and can make up for the shortcomings of the two-dimensional coil while retaining the advantages of the two-dimensional coil.

[0033] The three-dimensional coil of this design has a simple and compact structure, is easy to manufacture, has a low production cost, a wide range of applications, and its operating frequency meets the requirements of the operating frequency range specified by international standards.

[0034] According to actual needs, the value and quantity of the compensation capacitor and inductor used for impedance matching can be adjusted, the coil operating frequency can be flexibly adjusted or the coil performance can be optimized, so as to achieve the purpose of being suitable for various frequency bands or improving transmission efficiency without redesigning new transceiver coils. The shapes of the transmitting coil and the receiving coil can also be modified according to actual needs or aesthetic requirements. The materials used in the coils are the most commonly used materials, which can achieve higher power transmission efficiency at a lower cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the overall three-dimensional structure of a cross-shaped coil for wireless power transmission according to a preferred embodiment of the present invention from a first viewing angle;

[0036] Figure 2 A schematic diagram of the overall stereoscopic structure of a cross-shaped coil for wireless power transmission according to a preferred embodiment of the present invention from a second viewing angle;

[0037] Figure 3 A schematic diagram of a three-dimensional structure of a cross-shaped coil for wireless power transmission according to a preferred embodiment of the present invention, in which the coil is disassembled from above from a first viewing angle;

[0038] Figure 4 It is a schematic diagram of a three-dimensional structure of an upper disassembled coil and a lower disassembled coil combined according to a preferred embodiment of a cross-shaped coil for wireless power transmission of the present invention;

[0039] Figure 5 A schematic diagram of a three-dimensional structure of a disassembled coil according to a preferred embodiment of a cross-shaped coil for wireless power transmission of the present invention;

[0040] Figure 6 A schematic diagram of a three-dimensional structure of a fixed coil and a substrate assembly according to a preferred embodiment of a cross-shaped coil for wireless power transmission of the present invention;

[0041] Figure 7 A schematic diagram of the combined structure of an upper disassembled coil and a lower disassembled coil according to a preferred embodiment of a cross-shaped coil for wireless power transmission of the present invention;

[0042] Figure 8 A schematic diagram of the structure of a coil clamping assembly according to a preferred embodiment of a cross-shaped coil for wireless power transmission of the present invention;

[0043] Fig. 9 A schematic diagram of the combined structure of a plug and a side plug-in unit according to a preferred embodiment of a cross-shaped coil for wireless power transmission of the present invention;

[0044] Fig.10 For the present invention Fig. 9Enlarged view of the structure at point a in the figure.

[0045] Fig.11 Magnetic field distribution diagrams of different planes of a three-dimensional coil designed for a preferred embodiment of a cross-shaped coil for wireless power transmission according to the present invention;

[0046] (a) Coil magnetic field distribution in the XOY plane;

[0047] (b) Coil magnetic field distribution in the YOZ plane;

[0048] Fig.12 A graph showing a reflection coefficient S11 of a transmitting coil according to a preferred embodiment of a cross coil for wireless power transmission of the present invention;

[0049] Fig.13 FIG. 1 is a graph showing a reflection coefficient S11 of a receiving coil according to a preferred embodiment of a cross coil for wireless power transmission according to the present invention.

[0050] In the figure: 1-first transmitting coil, 2-first substrate, 3-side plug-in, 4-plug, 5-second substrate, 6-second transmitting coil, 7-first slot, 8-upper substrate, 9-upper transmitting coil, 10-lower transmitting coil, 11-lower substrate, 12-second slot, 13-third slot, 14-positioning slot, 15-L-shaped clamp, 16-first side limiting groove, 17-second side limiting groove, 18-first conical clamp, 19-second conical clamp, 20-through inner hole, 21-built-in groove, 22-built-in spring, 23-arc-shaped clamp. DETAILED DESCRIPTION

[0051] In order to make the technical solution of the present invention more clear and specific to those skilled in the art, the present invention is further described in detail below in conjunction with embodiments and drawings, but the implementation manner of the present invention is not limited thereto.

[0052] like Figure 1-Figure 10 As shown, the cross-shaped coil for wireless power transmission provided in this embodiment includes a first transmitting coil 1 and a second transmitting coil 6;

[0053] The first transmitting coil 1 and the second transmitting coil 6 are orthogonally formed, and the first transmitting coil 1 and the second transmitting coil 6 are connected in series;

[0054] The turns of the first transmitting coil 1 and the second transmitting coil 6 are crossed at equal intervals to form an orthogonal connection.

[0055] In this embodiment, the first transmitting coil 1 is mounted on the first substrate 2, the second transmitting coil 6 is mounted on the second substrate 5, and a second slot 12 penetrating the first transmitting coil 1 is provided on the second substrate 5;

[0056] A third slot 13 is also provided on the second substrate 5 .

[0057] like Fig.11 As shown in the figure, the magnetic field distribution of different planar coils is simulated and analyzed.

[0058] The display shows the coil magnetic field distribution in the XOY plane;

[0059] The figure shows the coil magnetic field distribution in the YOZ plane. It can be seen that a highly uniform magnetic field can be generated around the coil in each plane.

[0060] Since the designed coil is a three-dimensional structure, the magnetic fields generated by the two coils combined will radiate the magnetic field into three-dimensional space, which can obtain a wider and more uniform magnetic field than a single planar coil, and the magnetic field distribution range will cover a larger space, achieving good all-round (horizontal direction, vertical direction, angular rotation) anti-offset performance independent of the position of the receiving coil.

[0061] In this embodiment, the first transmitting coil 1 and the first substrate 2 are formed by clamping an upper disassembled coil group and a lower disassembled coil group;

[0062] The upper disassembled coil assembly passes through the second slot 12 and the third slot 13 and is connected to the lower disassembled coil assembly through the first clamping assembly and the second clamping assembly.

[0063] In this embodiment, the upper disassembled coil assembly includes an upper transmitting coil 9, an upper substrate 8 and a first slot 7;

[0064] An upper transmitting coil 9 is installed on the top of the upper substrate 8, and a first slot 7 for accommodating the second transmitting coil 6 is opened on one side of the upper substrate 8. The upper transmitting coil 9 passes through the second slot 12 and is clamped with the lower disassembled coil group.

[0065] In this embodiment, the lower disassembled coil assembly includes a lower transmitting coil 10 and a lower substrate 11;

[0066] A lower transmitting coil 10 is installed on the top of the lower substrate 11, and the cross sections of the upper transmitting coil 9 and the lower transmitting coil 10 are in contact and fit with each other.

[0067] In this embodiment, the first clamping assembly includes a clamping slot 14, an L-shaped clamping member 15, a first side limiting groove 16, a second side limiting groove 17, a first tapered clamping member 18 and a second tapered clamping member 19;

[0068] A locking slot 14 is installed on both sides of the end of the upper transmitting coil 9, and an L-shaped clamp 15 inserted into the locking slot 14 is installed on the ends of both sides of the lower transmitting coil 10. Second side limiting grooves 17 are opened on both sides of the L-shaped clamp 15 and a first conical clamp 18 is installed. A first side limiting groove 16 is opened on the inner side of the locking slot 14 and a second conical clamp 19 is installed.

[0069] In this embodiment, the second clamping assembly includes a plug 4, a side plug 3, a built-in groove 21, a built-in spring 22, a through inner hole 20 and an arc-shaped clamp 23;

[0070] A plug 4 is installed on the top edge of the upper base plate 8, and a side plug-in unit 3 is installed on the top edge of the lower base plate 11. A through inner hole 20 is provided at the inner end of the plug 4, and a built-in groove 21 is provided on the inner side of the side plug-in unit 3. A built-in spring 22 is installed on the inner wall of the built-in groove 21, and an arc-shaped clamp 23 is installed on the outer end of the built-in spring 22. The arc-shaped clamp 23 is inserted into the through inner hole 20 and cooperates with the plug 4.

[0071] In this embodiment, the first transmitting coil 1 and the second transmitting coil 6 cooperate orthogonally and cooperate with the receiving coil;

[0072] The receiving coil is placed between the first transmitting coil 1 and the second transmitting coil 6 at an angle of 45° to the first transmitting coil 1 and the second transmitting coil 6 .

[0073] Next, let's introduce the receiving coil. The designed receiving coil is a double-sided planar square spiral coil. Its structure is as follows Figure 4 As shown. The designed receiving coil must meet the requirements of simple structure, suitable size, easy to study, and size and shape suitable for embedding in electrical equipment, so a smaller traditional square planar spiral coil is chosen. The reason for designing the receiving coil as a double-sided coil is to increase the self-inductance of the receiving coil, and the winding method, line width, and spacing of the coils on both sides are the same.

[0074] Then, the coils on both sides are connected in series by vias to form a complete double-sided square spiral coil. The size of the designed receiving coil is 60×60mm 2 The PCB substrate material is FR-4, the substrate thickness is 1.6 mm, the copper layer thickness of each coil is 1 ounce, the number of turns of the coil is 8, the width of each turn of the coil is 2 mm, and the spacing between the lines is 1 mm. The following Table I shows the specific physical dimensions of the coil and the receiving coil.

[0075] Since the electromagnetic simulation software used cannot produce overlapping parts between the substrate and the coil, the intersection of the two square coils is isolated during the simulation design, and then the two planar square spiral coils are connected according to the designed three-dimensional coil shape through routing and vias to form a complete three-dimensional coupler, such as Figure 1As shown. The feed line mode of the transmitting coil and the receiving coil selects side feeding to introduce excitation. The determined coil operating frequency is 13.56MHz. In order to make the transmitting coil and the receiving coil both at the set operating frequency, it is selected to tune by adding compensation capacitors and inductors. A pair of capacitors and inductors are added to the transmitting coil and the receiving coil. C1 and L1 are the compensation capacitors and inductors of the transmitting coil, and CR and LR are the compensation capacitors and inductors of the receiving coil.

[0076] The operating frequency is expressed as: Table 2 shows the values ​​of compensation capacitor and inductor of each coil.

[0077] Table 2 Parameters of model compensation capacitor and inductor

[0078]

[0079] The 3D diagram of the simulation model is as follows Figure 5 The HFSS electromagnetic simulation software is used to simulate and analyze the designed WPT system based on three-dimensional coupling coils, and the transmitting coil and the receiving coil are connected to the compensation capacitor and inductor for tuning, as shown below Fig.12 , 13 As shown, after adjusting the values ​​of the compensation capacitor and inductor, the resonant frequencies of the transmitting coil and the receiving coil are adjusted to f=13.56MHz, so that the transmitting and receiving coils resonate and transmit energy. Combining the magnetic field distribution characteristics of the two orthogonal planar square spiral coils, the receiving coil is rotated 45° and placed 40mm away from the center of the three-dimensional transmitting coil. Fig.12 , 13 As shown, at this time, the resonant frequencies of the transmitting coil and the receiving coil are both at 13.56MHz, which can generate resonant transmission energy. And the reflection coefficients S11 of the two coils are very small, which proves that the impedance matching between the two is very good and the energy loss is also very small.

[0080] The above description is only a further embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the scope disclosed by the present invention, which belong to the protection scope of the present invention.

Claims

1. A cross coil for wireless power transmission, characterized in that: It comprises a first transmitting coil (1) and a second transmitting coil (6); The first transmitting coil (1) and the second transmitting coil (6) are orthogonally formed, and the first transmitting coil (1) and the second transmitting coil (6) are connected in series; Each turn of the first transmitting coil (1) and the second transmitting coil (6) are crossed at equal intervals to form an orthogonal connection.

2. The cross coil for wireless power transmission according to claim 1, characterized in that: The first transmitting coil (1) is mounted on a first substrate (2), the second transmitting coil (6) is mounted on a second substrate (5), and a second slot (12) is provided on the second substrate (5) and is penetrated by the first transmitting coil (1); A third slot (13) is also provided on the second base plate (5).

3. The cross coil for wireless power transmission according to claim 2, characterized in that: The first transmitting coil (1) and the first substrate (2) are formed by clamping an upper disassembled coil group and a lower disassembled coil group; The upper disassembled coil assembly passes through the second slot (12) and the third slot (13) and is clamped with the lower disassembled coil assembly through the first clamping assembly and the second clamping assembly.

4. The cross coil for wireless power transmission according to claim 3, characterized in that: The upper disassembled coil assembly comprises an upper transmitting coil (9), an upper base plate (8) and a first slot (7); An upper transmitting coil (9) is installed on the top of the upper substrate (8), and a first slot (7) for accommodating a second transmitting coil (6) is provided on one side of the upper substrate (8). The upper transmitting coil (9) passes through the second slot (12) and is clamped with the lower disassembled coil assembly.

5. The cross coil for wireless power transmission according to claim 4, characterized in that: The lower disassembled coil assembly comprises a lower transmitting coil (10) and a lower substrate (11); A lower transmitting coil (10) is installed on the top of the lower substrate (11), and the cross sections of the upper transmitting coil (9) and the lower transmitting coil (10) are in contact and fit with each other.

6. The cross coil for wireless power transmission according to claim 5, characterized in that: The first clamping assembly comprises a clamping slot (14), an L-shaped clamping piece (15), a first side limiting slot (16), a second side limiting slot (17), a first conical clamping piece (18) and a second conical clamping piece (19); The ends of the upper transmitting coil (9) are provided with latching slots (14) on both sides, the ends of the lower transmitting coil (10) are provided with L-shaped latches (15) which are inserted into and matched with the latching slots (14), the two sides of the L-shaped latches (15) are provided with second side limiting slots (17) and are provided with first conical latches (18), and the inner side of the latching slots (14) is provided with a first side limiting slot (16) and is provided with a second conical latch (19).

7. The cross coil for wireless power transmission according to claim 6, characterized in that: The second clamping assembly comprises a plug (4), a side plug (3), a built-in groove (21), a built-in spring (22), a through inner hole (20) and an arc-shaped clamp (23); A plug (4) is installed on the top edge of the upper base plate (8), a side plug (3) is installed on the top edge of the lower base plate (11), a through inner hole (20) is provided at the inner end of the plug (4), a built-in groove (21) is provided on the inner side of the side plug (3), a built-in spring (22) is installed on the inner wall of the built-in groove (21), an arc-shaped clamp (23) is installed on the outer end of the built-in spring (22), and the arc-shaped clamp (23) is inserted into the through inner hole (20) and cooperates with the plug (4).

8. The cross coil for wireless power transmission according to claim 7, characterized in that: The first transmitting coil (1) and the second transmitting coil (6) cooperate orthogonally and cooperate with the receiving coil; The receiving coil is placed between the first transmitting coil (1) and the second transmitting coil (6) at an angle of 45° to the first transmitting coil (1) and the second transmitting coil (6).

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