Multi-mode wireless power transmission system and adaptive optimization method thereof

Abstract

The invention provides a multi-mode wireless electric energy transmission system and an adaptive optimization method thereof, the wireless electric energy transmission system comprises a plurality of variable capacitors, an array device and a power supply, the array device is provided with a plurality of adjacent parallel coils, the coils are mutually independent and are connected in series with at least one variable capacitor, and the power supply is electrically connected with the array device; the wireless electric energy transmission system is provided with a plurality of working modes including a transmitter, a repeater and a receiver, and the wireless electric energy transmission system adapts to different working modes by powering on / powering off each coil and adjusting each variable capacitor, so that the wireless electric energy transmission of the equivalent closed-loop coil of the array device is in an optimal state in the current working mode. The wireless power transmission system has the beneficial effects that the power transmission efficiency of the wireless power transmission system is improved, and efficient integration and tuning of the transmitter, the receiver and the repeater are realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless power transmission, and in particular relates to a multi-mode wireless power transmission system and an adaptive optimization method thereof. Background Art

[0002] Wireless power transfer (WPT) is a promising power technology that can provide efficient and safe power supply in a variety of power applications. Compared with traditional wires and cables, the application of WPT technology can eliminate the need for these physical connections, thereby improving the waterproof and dustproof performance of electronic devices. Therefore, WPT technology is expected to become an ideal power solution for IoT devices in various environments. Due to these significant advantages, the standardization, legislation, and research and development of WPT technology have attracted widespread attention, and it is expected to be widely used in many electronic devices. However, despite the great potential of WPT technology, there are still some challenges that need to be addressed in its practical application, one of which is the lack of effective design methods for transmitters, receivers, and repeaters. The geometry of the coil is crucial to the performance of the WPT system because it directly affects the power transfer efficiency (PTE) and magnetic field leakage. During high-power transmission, reducing magnetic field leakage is key to avoid radiation exposure to the human body and electromagnetic compatibility (EMC) issues. Therefore, how to optimize the coil design of transmitters, receivers, and repeaters to meet the needs of different devices has become the key to promoting the widespread application of WPT technology. Summary of the invention

[0003] In view of this, the present invention aims to propose a multi-mode wireless power transmission system and its adaptive optimization method, so as to improve the power transmission efficiency of the wireless power transmission system through multi-mode coil design and optimization algorithm, and realize efficient integration and tuning of transmitters, receivers and repeaters to meet the needs of different electronic devices.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0005] Multimode wireless power transfer system.

[0006] Furthermore, the wireless power transmission system includes a plurality of variable capacitors, an array device, and a power supply, wherein the array device is provided with a plurality of adjacent parallel coils, each coil being independently connected in series with at least one of the variable capacitors, and the power supply is electrically connected to the array device;

[0007] The wireless power transmission system has several working modes, including transmitter, repeater, and receiver. By energizing / de-energizing each coil and adjusting each variable capacitor to adapt to different working modes, the array device's equivalent closed-loop coil is in the optimal wireless power transmission state under the current working mode.

[0008] Furthermore, a method for adaptively optimizing a wireless power transmission system is provided, based on the multi-mode wireless power transmission system, wherein when the wireless power transmission system is in a receiver mode, the shape of the array receiving coil is optimized according to the shape of the corresponding transmitting coil, and the necessary induced voltage and magnetic field strength for receiving electric energy are ensured;

[0009] When the wireless power transmission system is in transmitter mode, the input power of each coil is changed to optimize the magnetic dipole moment distribution of the array device to obtain the best transmitter equivalent coil;

[0010] When the wireless power transmission system is in the repeater mode, the variable capacitors of each coil are adjusted according to the resonant frequency to form a tunable relay array to focus the magnetic field on the receiver.

[0011] Furthermore, when the wireless power transmission system is in the receiver mode, the shape of the array receiving coil is optimized according to the following objective function F:

[0012]

[0013] Where, Min m total To minimize the weight of the coil, e total (t) is the total induced voltage of the coil at time t, V0 is the reference voltage, ε is the allowable induced voltage deviation range, H P (t) is the magnetic field intensity at point P at time t, H o is the critical magnetic field strength.

[0014] Furthermore, when the wireless power transmission system is in receiver mode, a compensation capacitor C1 is connected in series between the power supply and the array device, and a compensation capacitor C2 is connected in series to the main circuit of the transmitter corresponding to the wireless power transmission system to achieve resonant matching.

[0015] Furthermore, when the wireless power transmission system is in the transmitter mode, the optimal current distribution is obtained by calculating the loop current values ​​of all the array coils, and a closed loop area is formed as a transmitting coil by winding a wire along the outer contour boundary of the coils with the same magnetic dipole moment to maximize the power transmission efficiency;

[0016] The array grid coil conversion circulation current is as follows:

[0017]

[0018] In the formula, I Mesh ,I Loop They are the array grid coil current and loop current respectively.

[0019] Furthermore, when the direction of the magnetic dipole moment of the closed-loop region is the same as the emission direction, the outer contour boundary is wound in a forward winding manner;

[0020] When the direction of the magnetic dipole moment of the closed-loop region is opposite to the emission direction, the outer contour boundary is wound in a reverse winding manner.

[0021] Furthermore, when the wireless power transmission system is in repeater mode, the negative refractive index of the array coil close to the receiving coil is reduced and the negative refractive index of the array coil far from the receiving coil is increased by adjusting the variable capacitor, so that the resonant frequency of the wireless power transmission system is matched with the WPT system configured therewith.

[0022] Furthermore, an electronic device includes a processor and a memory that is communicatively connected to the processor and is used to store executable instructions of the processor, and the processor is used to execute the adaptive optimization method of the wireless power transmission system.

[0023] Furthermore, a computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for adaptively optimizing the wireless power transmission system is implemented.

[0024] Compared with the prior art, the multi-mode wireless power transmission system and the adaptive optimization method thereof described in the present invention have the following beneficial effects:

[0025] (1) The wireless power transmission system adaptive optimization method described in the present invention realizes multi-mode adaptive optimization, improves the wireless power transmission efficiency, magnetic field focusing accuracy and system compatibility.

[0026] (2) The multi-mode wireless power transmission system of the present invention, in the receiver mode, designs the shape of the receiving coil based on the gradient optimization algorithm, combines the equivalent closed-loop induced voltage optimization method, makes the coil shape adapt to the transmitting coil, and realizes resonance matching through the series compensation capacitor, ensures that the induced voltage is within the reference range, optimizes the magnetic field strength, minimizes the coil mass, and realizes compact design and high resolution;

[0027] (3) The multi-mode wireless power transmission system of the present invention, in the transmitter mode, calculates the magnetic dipole moment by using the distribution of the loop current of the mesh conductor, winds the wire along the contour line direction to form a closed loop area as a transmitting coil, optimizes the magnetic field distribution by adjusting the input power, reduces energy loss and enhances power transmission efficiency;

[0028] (4) The multi-mode wireless power transmission system described in the present invention, in the repeater mode, achieves precise control of the negative refractive index by adjusting the variable capacitor, thereby focusing the magnetic field to the receiver position, while ensuring matching with the resonant frequency of the WPT system, thereby improving the magnetic field concentration and transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0030] Figure 1 A schematic diagram of the planar structure of an array device according to an embodiment of the present invention;

[0031] Figure 2 A schematic diagram of the magnetic field induction intensity of the coil according to an embodiment of the present invention;

[0032] Figure 3 A schematic diagram of an equivalent coil of a transmitter according to an embodiment of the present invention;

[0033] Figure 4 A schematic diagram of an equivalent coil of a transmitter according to an embodiment of the present invention;

[0034] Figure 5 A schematic diagram of a resonant matching circuit principle diagram of a wireless power transmission system according to an embodiment of the present invention;

[0035] Figure 6 A schematic diagram of mesh current and loop current of a 2×2 grid conductor according to an embodiment of the present invention;

[0036] Figure 7 A schematic diagram of a magnetic dipole moment generated by a loop current according to an embodiment of the present invention;

[0037] Figure 8 A schematic diagram of magnetic dipole moments generated by a plurality of equal loop currents according to an embodiment of the present invention;

[0038] Fig. 9 A schematic diagram of current cancellation of a mesh conductor according to an embodiment of the present invention;

[0039] Fig.10 It is a schematic diagram of the magnetic dipole moment contour lines according to an embodiment of the present invention;

[0040] Fig.11 This is a schematic diagram of an optimized transmitting coil according to an embodiment of the present invention;

[0041] Fig.12 The figure is a schematic diagram of the structure of the tunable coil of the repeater according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0043] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0044] Multi-mode wireless power transfer systems, such as Figure 1 As shown, the wireless power transmission system includes a plurality of variable capacitors, an array device, and a power supply. The array device is provided with a plurality of adjacent parallel coils and placed one by one in a mesh conductor. Each coil is independently connected in series with at least one of the variable capacitors. The power supply is electrically connected to the array device. Optionally, the array device substrate is made of flexible polyethylene, and the coil is in a square spiral shape.

[0045] The wireless power transmission system is provided with several working modes, including a transmitter, a repeater, and a receiver. Based on the multi-mode wireless power transmission system, the adaptive optimization method of the wireless power transmission system makes the array equivalent closed-loop coil in the optimal state of wireless power transmission in the current working mode by energizing / de-energizing each coil and adjusting each variable capacitor to adapt to different working modes. Specifically, when used as a receiver, a gradient-based optimization algorithm is used to determine the optimal receiving coil shape for this wireless power transmission system when the transmitting coil is predetermined; when used as a transmitter, the mesh conductor is regarded as a transmitter array, and a coil design method based on current distribution is established by calculating the magnetic dipole moment generated by the current distribution of the mesh conductor; when used as a repeater, there are two types of unit cells, which can be independently tuned to have an appropriate negative refractive index. When the transmitting coil and the receiving coil are predetermined, the magnetic field is focused to the location of the Rx coil to reduce electromagnetic field leakage and improve the efficiency of the wireless power transmission system.

[0046] Embodiment 1: When the wireless power transmission system is in receiver mode.

[0047] When the transmitting coil is predetermined, the performance of the wireless power transmission system depends largely on the coil structure design of the receiver module. The shape of the array receiving coil is optimized according to the corresponding transmitting coil shape, and the necessary induced voltage and magnetic field strength for receiving electric energy are guaranteed. The shape of the array receiving coil is optimized according to the following objective function F:

[0048]

[0049] Where, Min m total To minimize the weight of the coil, e total (t) is the total induced voltage of the coil at time t, V0 is the reference voltage, ε is the allowable induced voltage deviation range, H P (t) is the magnetic field intensity at point P at time t, H o is the critical magnetic field strength. Figure 2 As shown, considering that any shape of coil can be approximated as a set of line segments, assuming that the transmitting coil is decomposed into a straight conductor, and then according to the Biot-Savart law, the magnetic field strength induced by the current in the line segment AB at a point P of the receiving coil is:

[0050]

[0051] In the formula, I peak is the peak current; ω is the angular frequency of the current. Using the superposition principle, the total magnetic field strength induced by the entire transmitter coil is the sum of the magnetic field strengths induced by each part of the transmitting coil, as shown below:

[0052]

[0053] like Figure 3 As shown, the grid induced voltage e at (i, j) (i,j) (t) The theoretical derivation is as follows:

[0054]

[0055] Where A is the surface area of ​​a grid; μ0 is the permeability of free space; and ds is the surface vector of an infinitesimal region. (i,j) (t) The computational burden of solving the problem is that the entire design domain of the receiving coil is finely discretized into each grid, and the magnetic field strength inside each grid changes linearly. (i,j) (t) can be approximated as:

[0056] e total (t) = ∑ i ∑ j e (i,j) (t);

[0057] Further, such as Figure 3 As shown in the figure, the black area of ​​the cell indicates that the received magnetic induction intensity is strong, and the white area indicates that the magnetic induction intensity is very low, and the current in the loop can be almost ignored. From the perspective of the magnetic field, if the parts of the adjacent loops with the same number of turns have equal currents and opposite directions, the magnetic fields induced on the adjacent sides of the two loops will cancel each other out. The remaining line segments form an equivalent closed loop. Figure 4 As shown, the induced voltage of the array coil composed of all independent cells is the same as the induced voltage of the equivalent closed loop, thereby obtaining the optimal receiving coil shape and minimizing the total mass of the coil. Usually, the size of the array coil is small enough so that the designed coil shape has a high resolution and a smooth coil shape.

[0058] Optional such as Figure 5 As shown, when the wireless power transmission system is in the receiver mode, a compensation capacitor C1 is connected in series between the power supply and the array device, and a compensation capacitor C2 is connected in series to the main loop of the transmitter corresponding to the wireless power transmission system to achieve resonant matching.

[0059] Embodiment 2: When the wireless power transmission system is in transmitter mode.

[0060] The WPT between the mesh conductor and the receiving coil is considered as a multiple-input single-output (MISO) system. The input power of each coil is changed to optimize the magnetic dipole moment distribution of the array device and obtain the best transmitter equivalent coil. Specifically, the loop current values ​​of all array coils are calculated to obtain the optimal current distribution, and the wire is wound along the outer contour boundary of the coil with the same magnetic dipole moment to form a closed loop area as the transmitting coil to maximize the power transmission efficiency. The principle is as follows:

[0061] like Figure 6 As shown, with 2×2 mesh conductors as columns, the mesh current is converted into loop current. According to Kirchhoff's current law, the relationship between the mesh current and loop current of each mesh can be derived as follows:

[0062]

[0063] When extended to the n×n grid conductor of this embodiment, the array grid coil conversion circulation current is as follows:

[0064]

[0065] In the formula, I Mesh ,I Loop are the array grid coil current and loop current respectively. Figure 7 As shown, it is assumed that the current flows along the loop C, where I represents the current at position r on the loop C. By using the area of ​​the loop C and the vector n perpendicular to the loop C, the equation for the magnetic dipole moment can be derived:

[0066] m=Isn;

[0067] In a mesh conductor, since the area of ​​each mesh is the same, the S of each mesh is equal. Therefore, the magnitude of the magnetic dipole moment is proportional to the magnitude of the loop current, and the magnetic dipole moment is a vector perpendicular to the mesh conductor. Figure 8 As shown in , consider a region with the same magnetic dipole moment in the mesh conductor. Since the area of ​​each mesh is constant, the magnitude of the magnetic dipole moment is only proportional to the magnitude of the loop current. Therefore, the same magnitude of the magnetic dipole moment means the same magnitude of the loop current. Fig. 9 As shown, the currents in adjacent grids cancel each other out, leaving only the current flowing to the outside. Therefore, when a coil is wound around the outer contour of a mesh conductor area with the same magnetic dipole moment and current is passed through it, it is equivalent to reproducing all the loop currents in the area.

[0068] Further, such as Fig.10 As shown in the figure, there are 5 contour lines. When a coil is created along the contour line direction and current flows through it, a magnetic dipole moment is generated. This process can approximately reflect the distribution of magnetic dipole moments in a mesh conductor. Fig.11As shown, in the above analysis, the magnetic dipole moment generated by the mesh conductor is assumed to be positive and monotonically increases from the outside of the coil to the center. However, depending on the sign of the loop current, the value of the magnetic dipole moment may be negative, or in some cases decrease. In this case, the reduction of the magnetic dipole moment can be represented by winding the coil in the opposite direction around the contour line. The solid line represents clockwise winding, and the dotted line represents counterclockwise winding, that is: when the direction of the magnetic dipole moment of the closed loop area is the same as the emission direction, the outer contour boundary is wound in a positive winding manner; when the direction of the magnetic dipole moment of the closed loop area is the same as the emission direction, the outer contour boundary is wound in a reverse winding manner.

[0069] Embodiment 3: When the wireless power transmission system is in repeater mode.

[0070] The variable capacitors of each coil are adjusted according to the resonant frequency to form a tunable relay array to focus the magnetic field on the receiver. Specifically, the negative refractive index of the array coil close to the receiving coil is reduced by adjusting the variable capacitor, and the negative refractive index of the array coil far from the receiving coil is increased, so that the resonant frequency of the wireless power transmission system and the WPT system configured with it is matched.

[0071] like Fig.12 As shown in the figure, taking a 5×5 tunable plate as an example, the 9 cells closer to the receiving coil are defined as type 1 cells with a negative refractive index of -1; the remaining 16 cells are adjusted to type 2 cells with a negative refractive index of -3. In order to facilitate the adjustment of the cell type, the refractive index of each cell can be easily changed by mechanically adjusting the variable capacitor.

[0072] Those of ordinary skill in the art will appreciate that the units and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0073] In the several embodiments provided in the present application, it should be understood that the disclosed methods and systems can be implemented in other ways. For example, the division of the units described above is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. The above-mentioned units may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiments of the present invention.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A multi-mode wireless power transmission system, characterized in that: The wireless power transmission system includes a plurality of variable capacitors, an array device, and a power supply. The array device is provided with a plurality of adjacent parallel coils, each coil is independently connected in series with at least one of the variable capacitors, and the power supply is electrically connected to the array device. The wireless power transmission system has several working modes, including transmitter, repeater, and receiver. By energizing / de-energizing each coil and adjusting each variable capacitor to adapt to different working modes, the array device's equivalent closed-loop coil is in the optimal wireless power transmission state under the current working mode.

2. A method for adaptive optimization of a wireless power transmission system, based on the multi-mode wireless power transmission system of claim 1, characterized in that: When the wireless power transmission system is in the receiver mode, the shape of the array receiving coil is optimized according to the shape of the corresponding transmitting coil, and the necessary induced voltage and magnetic field strength for receiving electric energy are ensured; When the wireless power transmission system is in transmitter mode, the input power of each coil is changed to optimize the magnetic dipole moment distribution of the array device to obtain the best transmitter equivalent coil; When the wireless power transmission system is in the repeater mode, the variable capacitors of each coil are adjusted according to the resonant frequency to form a tunable relay array to focus the magnetic field on the receiver.

3. The method for adaptive optimization of a wireless power transmission system according to claim 2, characterized in that: When the wireless power transmission system is in the receiver mode, the array receiving coil shape is optimized according to the following objective function F: Where, Min m total To minimize the weight of the coil, e total (t) is the total induced voltage of the coil at time t, V0 is the reference voltage, ε is the allowable induced voltage deviation range, H P (t) is the magnetic field intensity at point P at time t, H o is the critical magnetic field strength.

4. The method for adaptive optimization of a wireless power transmission system according to claim 2, characterized in that: When the wireless power transmission system is in receiver mode, a compensation capacitor C1 is connected in series between the power supply and the array device, and a compensation capacitor C2 is connected in series to the main circuit of the transmitter corresponding to the wireless power transmission system to achieve resonant matching.

5. The method for adaptive optimization of a wireless power transmission system according to claim 2, characterized in that: When the wireless power transmission system is in the transmitter mode, the optimal current distribution is obtained by calculating the loop current values ​​of all the array coils, and the wire is wound along the outer contour boundary of the coils with the same magnetic dipole moment to form a closed loop area as the transmitting coil to maximize the power transmission efficiency; The array grid coil conversion circulation current is as follows: In the formula, I Mesh ,I Loop They are the array grid coil current and loop current respectively.

6. The method for adaptive optimization of a wireless power transmission system according to claim 5, characterized in that: When the direction of the magnetic dipole moment of the closed-loop region is the same as the emission direction, a positive winding method is used to wind the outer contour boundary; When the direction of the magnetic dipole moment of the closed-loop region is opposite to the emission direction, the outer contour boundary is wound in a reverse winding manner.

7. The method for adaptive optimization of a wireless power transmission system according to claim 2, characterized in that: When the wireless power transmission system is in repeater mode, the negative refractive index of the array coil close to the receiving coil is reduced by adjusting the variable capacitor, and the negative refractive index of the array coil far away from the receiving coil is increased, so that the wireless power transmission system matches the resonant frequency of the WPT system configured with it.

8. An electronic device, comprising a processor and a memory connected to the processor for storing instructions executable by the processor, characterized in that: The processor is used to execute the wireless power transmission system adaptive optimization method described in any one of claims 2-7.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for adaptively optimizing a wireless power transmission system according to any one of claims 2 to 7 is implemented.

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