Sheet printing wireless power supply coil

Abstract

The invention discloses a sheet printing wireless power supply coil, which belongs to the technical field of magnetic coupling resonant wireless power transmission, and comprises two layers of coils which are arranged in parallel, and each layer of coil comprises a plurality of strands of wires which are spirally arranged in a plane, each strand of wire is connected in series with a split impedance tuning capacitor used for compensating inductive reactance difference between the wires and realizing optimal inter-strand current; wherein the parameter of the split impedance tuning capacitor is configured based on the minimum reference voltage between the wires; the minimum reference voltage between the wires is determined based on the minimum value of the voltage of each strand of wire in the optimal current distribution state; the optimal current distribution state means that the current distributed to each strand of wire enables the loss of the printed wireless power supply coil to be minimum. The sheet printing wireless power supply coil can solve the problem of resistance increase caused by uneven current distribution.

Description

Technical Field

[0001] The invention relates to a thin-plate printed wireless power supply coil, belonging to the technical field of magnetic coupling resonant wireless power transmission. Background Art

[0002] With advances in power electronics integration technology, printed circuit boards (PCBs) have become an important manufacturing method for coupling coils in wireless power transfer systems, particularly for mobile devices, drones, and other smart devices requiring lightweight receiver designs. This is due to their ease of production, high reliability, and light weight. However, at higher operating frequencies, skin and proximity effects significantly increase the AC resistance, posing a challenge to the application of printed wireless power transfer coils. Mitigating these effects is crucial for optimizing the AC resistance of printed wireless power transfer coils.

[0003] Existing methods for optimizing the AC internal resistance of printed wireless power supply coils mainly include structural parameter optimization, Litz structure, equally divided inductor design, and self-resonance. Structural parameter optimization optimizes structural parameters such as line width, line spacing, and number of strands, but the parameter design is complex and the internal resistance optimization effect is not obvious. The Litz structure uses the Litz structure of twisting technology to achieve the equivalence of the length of each strand and minimize the total magnetic flux between the strands, but it is difficult to apply to small-sized wireless power transmission systems. The equally divided inductor design ensures the consistency of the length of the stranded wires by regularly rotating the wires from the top layer to the bottom layer, solving the problem of inductance reduction caused by the different path lengths of the inner and outer strands, but it is only suitable for low-power wireless power transmission systems. Self-resonance achieves autonomous resonance through the distributed capacitance between the winding layers and the coil inductance, reducing the use of additional capacitance, but the system operating frequency is generally high, which is not conducive to practical application.

[0004] In summary, existing research focuses on optimizing the windings of printed circuit boards (PCBs), but does not consider the uneven current distribution caused by differences in the inductance and resistance of each branch line, which in turn increases the equivalent resistance of the winding. Summary of the Invention

[0005] The object of the present invention is to provide a thin-plate printed wireless power supply coil capable of solving the problem of resistance increase caused by uneven current distribution.

[0006] In order to achieve the above object, the present invention provides the following technical solutions: In a first aspect, the present invention provides a thin-plate printed wireless power supply coil comprising two layers of coils arranged in parallel, each layer of coil comprising a plurality of conductors arranged in a planar spiral, each conductor being connected in series with a split impedance tuning capacitor for compensating for inductive reactance differences between the conductors and achieving optimal current flow between the conductors; Among them, the parameters of the split impedance tuning capacitor are configured based on the minimum reference voltage between the conductors; the minimum reference voltage between the conductors is determined by the minimum voltage of each conductor under the optimal current distribution state; the optimal current distribution state means that the current distributed to each conductor minimizes the loss of the printed wireless power supply coil.

[0007] In combination with the first aspect, further, each strand of wire in each layer of coil is wound along a concentric path to form an equally spaced spiral wiring grid; each strand of wire in each layer of coil has internal resistance and self-inductance, and there is a mutual inductance and mutual resistance coupling relationship between the strands of wire, forming a mutually coupled inductive reactance network.

[0008] In combination with the first aspect, further, the number of strands of the wire in each layer of coil is the same, and the number of strands is greater than or equal to 3; the number of turns, line width and spacing of each strand of wire are consistent.

[0009] In combination with the first aspect, further, each split impedance tuning capacitor is symmetrically arranged in parallel around the periphery of the coil using a surface-mount capacitor packaging component of the same size.

[0010] In combination with the first aspect, further, each split impedance tuning capacitor is a multilayer chip ceramic capacitor.

[0011] In a second aspect, the present invention provides a method for configuring parameters of a split impedance tuning capacitor in a thin-plate printed wireless power supply coil as described in any one of the first aspects, comprising: Based on the structural parameters of the two-layer coil, the internal resistance and self-inductance of each strand of wire are measured, as well as the mutual inductance and mutual resistance between the strands of wire, to obtain the equivalent resistance and equivalent inductance of each strand of wire; Construct the Lagrangian function based on the equivalent resistance and equivalent inductance of each wire; Based on the Lagrangian function, the optimal current distribution function is solved; Based on the optimal current distribution function, the minimum voltage of each conductor under the optimal current distribution state is obtained, and the minimum reference voltage between the conductors is determined; Calculate the parameters of the split impedance tuning capacitor based on the minimum reference voltage between the conductors.

[0012] In combination with the second aspect, further, the structural parameters include the size of the coil, the number of turns, the number of strands, and the width and thickness of a single-strand conductor.

[0013] In combination with the second aspect, further, the internal resistance and self-inductance of each strand of wire, as well as the mutual inductance and mutual resistance between strands of wire are measured by an impedance analyzer.

[0014] In combination with the second aspect, further, the equivalent resistance of each strand of wire is: ; in, represents the equivalent resistance, Indicates the The internal resistance of the stranded conductor, Indicates the Strand conductor and Mutual resistance between strands of conductors, Indicates the number of wire strands in each layer of coil; The equivalent inductance of each wire is: ; in, represents the equivalent resistance, Indicates the The self-inductance of the strands of wire, Indicates the Strand conductor and Mutual inductance between strands of conductor; Lagrangian function for: ; in, represents the current matrix flowing through each wire, , 、 、…、 Indicates that the flow passes through 1, 2, ..., The current in the strands, represents the Lagrange multiplier, represents the transpose operation, represents the conjugate operation, Indicates flow Total current of the strands; Optimal current distribution function for: ; in, Indicated by A column vector consisting of 1s in each row; Minimum reference voltage between conductors The calculation formula is:

[0015] in, represents the angular frequency, Indicates the minimum voltage of each conductor under the optimal current distribution state; The calculation formula for the capacitance value of the split impedance tuning capacitor is: ; in, Indicates the capacitance value of the split impedance tuning capacitor.

[0016] In a third aspect, the present invention provides a dynamic wireless power supply system, comprising a thin-film printed wireless power supply coil as described in any one of the first aspects, wherein one layer of coil serves as a transmitting coil and another layer of coil serves as a receiving coil; the transmitting coil is sequentially connected to a first compensation capacitor and an inverter unit, and the receiving coil is sequentially connected to a second compensation capacitor and a rectifier.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The thin-printed wireless power supply coil provided by this invention uses split impedance tuning capacitors to compensate for the impedance of each conductor. Optimal current distribution is achieved through parameter configuration of the split impedance tuning capacitors, optimizing the resistance of the printed circuit board windings. This not only optimizes the resistance of the printed circuit board windings but also eliminates the need for very high operating frequencies. It also increases the power density of the wireless power supply system during operation, thereby improving the overall efficiency of the wireless power supply system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic cross-sectional view of a printed circuit board winding provided by an embodiment of the present invention; Figure 2 This is a diagram of an equivalent model of a multi-strand winding of a printed circuit board provided by an embodiment of the present invention; Figure 3 is a schematic diagram of the minimum reference voltage provided by an embodiment of the present invention; Figure 4 is a schematic diagram of an impedance splitting resonant circuit provided by an embodiment of the present invention; Figure 5 This is a schematic diagram of the winding routing of a printed circuit board provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The technical solution of the present application will be further described in detail below in conjunction with specific implementation methods.

[0020] The embodiments of the present application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application. The embodiments of the present application and the technical features in the embodiments may be combined with each other unless there is a conflict.

[0021] The embodiment of the present application provides a thin-plate printed wireless power supply coil, such as Figure 1 As shown, it includes two layers of coils arranged in parallel, each layer of coil includes several strands of wire arranged in a planar spiral, and each strand of wire is connected in series with a split impedance tuning capacitor for compensating for the inductive reactance difference between the wires and achieving optimal current between the strands.

[0022] In this embodiment, the parameters of the split impedance tuning capacitor are configured based on the minimum reference voltage between the conductors; the minimum reference voltage between the conductors is determined based on the minimum voltage of each conductor under the optimal current distribution state; the optimal current distribution state means that the current distributed to each conductor minimizes the loss of the printed wireless power supply coil.

[0023] The thin-plate printed wireless power supply coil provided in the embodiment of the present application has a split impedance tuning capacitor connected in series on each strand of conductor to compensate for the difference in inductive reactance between the conductors. The parameters of the split impedance tuning capacitor are configured to achieve optimal current between strands. The split-line impedance tuning optimizes the current distribution and reduces winding losses, which can solve the problem of increased resistance caused by uneven current distribution and improve the efficiency of the wireless power supply system.

[0024] In one possible embodiment, each strand of wire in each layer of coils is wound along a concentric path to form a spiral wiring grid with equal spacing; each strand of wire in each layer of coils has internal resistance and self-inductance, and there is a mutual inductance and mutual resistance coupling relationship between the strands of wires, forming a mutually coupled inductive reactance network.

[0025] In this embodiment, the number of strands of the conductors in each layer of coils is the same, and the number of strands is greater than or equal to 3; the number of turns, line width, and spacing of each strand of conductor are consistent.

[0026] Specifically, such as Figure 1 As shown, the thin-plate printed wireless power supply coil includes a top layer coil and a bottom layer coil, the top layer coil and the bottom layer coil are arranged in parallel, and each layer coil includes Strand conductor, each layer of coil The strands of conductor are arranged in a plane spiral and wound together The width of each conductor is , thickness is , the spacing is The total height of the thin-plate printed wireless power supply coil composed of the top coil and the bottom coil is .

[0027] Each layer of coils consists of The wires are arranged in parallel, which can reduce the skin effect. However, each wire still affects the other, which is called the proximity effect.

[0028] In a possible embodiment, the split impedance tuning capacitors are chip capacitor packaging components of the same size and are symmetrically arranged in parallel around the periphery of the coil.

[0029] In this embodiment, each split impedance tuning capacitor is a multilayer chip ceramic capacitor.

[0030] Specifically, such as Figure 5 As shown, the outer diameter of the printed circuit board winding is 76 mm and the inner diameter is 19 mm. Figure 1The structure shown is identical, consisting of a two-layer printed circuit board with a thickness of 1.6 mm. Each layer contains eight parallel spirally arranged conductors, each with a width of 0.44 mm, a thickness of 0.07 mm, and a spacing of 0.16 mm. Each conductor is connected in series with a split impedance tuning capacitor. The eight split impedance tuning capacitors are all arranged in parallel around the perimeter of the coil using surface-mounted capacitors of the same size, with the surface-mounted capacitors on both coil layers being symmetrical.

[0031] The thin-plate printed wireless power supply coil provided in the embodiment of the present application can be extended to other situations not limited to circular windings.

[0032] An embodiment of the present application provides a method for configuring parameters of a split impedance tuning capacitor in a thin-plate printed wireless power supply coil as provided in any embodiment of the present application, including: Based on the structural parameters of the two-layer coil, the internal resistance and self-inductance of each strand of wire are measured, as well as the mutual inductance and mutual resistance between the strands of wire, to obtain the equivalent resistance and equivalent inductance of each strand of wire; Construct the Lagrangian function based on the equivalent resistance and equivalent inductance of each wire; Based on the Lagrangian function, the optimal current distribution function is solved; Based on the optimal current distribution function, the minimum voltage of each conductor under the optimal current distribution state is obtained, and the minimum reference voltage between the conductors is determined; Calculate the parameters of the split impedance tuning capacitor based on the minimum reference voltage between the conductors.

[0033] In this embodiment, the structural parameters include the size of the coil, the number of turns, the number of strands, and the width and thickness of a single-strand conductor.

[0034] Specifically, the internal resistance and self-inductance of each strand of wire, as well as the mutual inductance and mutual resistance between strands of wire, are measured using an impedance analyzer.

[0035] The equivalent model of the multi-strand winding of the printed circuit board is as follows Figure 2 shown. Figure 2 middle, 、 、…、 Indicates that the flow passes through 1, 2, ..., The current in the strands, Indicates the The self-inductance of the strands of wire, Indicates the Strand conductor and Mutual inductance between the strands, Indicates the The internal resistance of the stranded conductor, Indicates the Strand conductor and Mutual resistance between strands of conductors, The angular frequency of the system is expressed as express, and operating frequency The relationship is .

[0036] In this embodiment, the equivalent resistance of each strand of wire is: ; in, represents the equivalent resistance, Indicates the The internal resistance of the stranded conductor, Indicates the Strand conductor and Mutual resistance between strands of conductors, Indicates the number of wire strands per layer of coils.

[0037] The equivalent inductance of each wire is: ; in, represents the equivalent resistance, Indicates the The self-inductance of the strands of wire, Indicates the Strand conductor and Mutual inductance between the conductor strands.

[0038] Lagrangian function for: ; in, represents the current matrix flowing through each wire, , 、 、…、 Indicates that the flow passes through 1, 2, ..., The current in the strands, represents the Lagrange multiplier, represents the transpose operation, represents the conjugate operation, Indicates flow The total current of the conductor strands.

[0039] By calculating the partial derivative of the Lagrangian function with respect to each variable and setting it to zero, we can get the mathematical expression: ; in, Express Ask about gradient.

[0040] Solving the mathematical expression, we can get the optimal current distribution function for: ; in, Indicated by A column vector consisting of rows of 1.

[0041] Based on the optimal current distribution function, the voltage across each conductor under the optimal current distribution state can be obtained through the existing derivation and calculation results. for: ; in, Represents an imaginary unit.

[0042] Minimum reference voltage between conductors The calculation formula is: ; in, represents the angular frequency, It indicates the minimum voltage of each conductor under the optimal current distribution state.

[0043] The calculation formula for the capacitance value of the split impedance tuning capacitor is: ; in, Indicates the capacitance value of the split impedance tuning capacitor.

[0044] The optimal current distribution phasor is Figure 3 As shown, the principle of the impedance splitting resonant circuit is as follows Figure 4 shown. Figure 3 and Figure 4 middle, 、 、 Indicates the flow through 、 、 The current in the strands, 、 、 Indicates the 、 、 The self-inductance of the strands of wire, 、 、 Indicates the 、 、 The internal resistance of the stranded conductor, 、 、 Indicates that the 、 、 The capacitance value of the split impedance tuning capacitor on the stranded conductor, 、 、 Indicates the 、 、 The voltage across the conductor, Re represents the real part and Im represents the imaginary part.

[0045] The parameter configuration method of the split impedance tuning capacitor in the thin-plate printed wireless power supply coil provided in the embodiment of the present application has the beneficial effects of the thin-plate printed wireless power supply coil provided in any embodiment of the present application.

[0046] An embodiment of the present application provides a dynamic wireless power supply system, including a thin-plate printed wireless power supply coil as provided in any embodiment of the present application, wherein one layer of coil serves as a transmitting coil and another layer of coil serves as a receiving coil; the transmitting coil is sequentially connected to a first compensation capacitor and an inverter unit, and the receiving coil is sequentially connected to a second compensation capacitor and a rectifier.

[0047] The dynamic wireless power supply system provided in the embodiment of the present application has the beneficial effects of the thin-plate printed wireless power supply coil provided in any embodiment of the present application.

[0048] The above is only a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A thin-plate printed wireless power supply coil, characterized in that: The invention comprises two layers of coils arranged in parallel, each layer of coils comprising a plurality of strands of conductors arranged in a plane spiral, each strand of conductor being connected in series with a split impedance tuning capacitor for compensating for the difference in inductive reactance between the conductors and achieving the optimal current between the strands; Among them, the parameters of the split impedance tuning capacitor are configured based on the minimum reference voltage between the conductors; the minimum reference voltage between the conductors is determined by the minimum voltage of each conductor under the optimal current distribution state; the optimal current distribution state means that the current distributed to each conductor minimizes the loss of the printed wireless power supply coil.

2. The thin-plate printed wireless power supply coil according to claim 1, characterized in that: The wires of each layer of coil are wound along concentric paths to form a spiral wiring grid with equal spacing. Each strand of wire in each layer of coil has internal resistance and self-inductance. There is a mutual inductance and mutual resistance coupling relationship between the strands of wire, forming a mutually coupled inductive reactance network.

3. The thin-plate printed wireless power supply coil according to claim 1, characterized in that: The number of strands of the wire in each layer of coil is the same and is greater than or equal to 3; the number of turns, wire width and spacing of each strand of wire are consistent.

4. The thin-plate printed wireless power supply coil according to claim 1, characterized in that: The split impedance tuning capacitors are symmetrically arranged on the periphery of the coil using chip capacitor packaging components of the same size.

5. The thin-plate printed wireless power supply coil according to claim 1, characterized in that: Each split impedance tuning capacitor is a multilayer chip ceramic capacitor.

6. A method for configuring parameters of a split impedance tuning capacitor in a thin-plate printed wireless power supply coil according to any one of claims 1 to 5, characterized in that: include: Based on the structural parameters of the two-layer coil, the internal resistance and self-inductance of each strand of wire are measured, as well as the mutual inductance and mutual resistance between the strands of wire, to obtain the equivalent resistance and equivalent inductance of each strand of wire; Construct the Lagrangian function based on the equivalent resistance and equivalent inductance of each wire; Based on the Lagrangian function, the optimal current distribution function is solved; Based on the optimal current distribution function, the minimum voltage of each conductor under the optimal current distribution state is obtained, and the minimum reference voltage between the conductors is determined; Calculate the parameters of the split impedance tuning capacitor based on the minimum reference voltage between the conductors.

7. The method for configuring parameters of a split impedance tuning capacitor in a thin-plate printed wireless power supply coil according to claim 6, characterized in that: Structural parameters include coil size, number of turns, number of strands, width and thickness of single-strand wire.

8. The method for configuring parameters of a split impedance tuning capacitor in a thin-plate printed wireless power supply coil according to claim 6, wherein: The internal resistance and self-inductance of each strand of wire, as well as the mutual inductance and mutual resistance between the strands of wire, are measured using an impedance analyzer.

9. The method for configuring parameters of a split impedance tuning capacitor in a thin-plate printed wireless power supply coil according to claim 6, wherein: The equivalent resistance of each wire is: ； in, represents the equivalent resistance, Indicates the The internal resistance of the stranded conductor, Indicates the Strand conductor and Mutual resistance between conductor strands, Indicates the number of wire strands in each layer of coil; The equivalent inductance of each wire is: ； in, represents the equivalent resistance, Indicates the The self-inductance of the strands of wire, Indicates the Strand conductor and Mutual inductance between strands of conductor; Lagrangian function for: ； in, represents the current matrix flowing through each wire, , 、 、…、 Indicates that the flow passes through 1, 2, ..., The current in the strands, represents the Lagrange multiplier, represents the transpose operation, represents the conjugate operation, Indicates flow Total current of the strands; Optimal current distribution function for: ； in, Indicated by A column vector consisting of 1s in each row; Minimum reference voltage between conductors The calculation formula is: ； in, represents the angular frequency, Indicates the minimum voltage of each conductor under the optimal current distribution state; The calculation formula for the capacitance value of the split impedance tuning capacitor is: ； in, Indicates the capacitance value of the split impedance tuning capacitor.

10. A dynamic wireless power supply system, characterized in that: It comprises a thin-plate printed wireless power supply coil as described in any one of claims 1 to 5, wherein one layer of coil serves as a transmitting coil and another layer of coil serves as a receiving coil; the transmitting coil is sequentially connected to a first compensation capacitor and an inverter unit, and the receiving coil is sequentially connected to a second compensation capacitor and a rectifier.

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