Three-dimensional omnidirectional wireless power transmission system based on three frequencies

Abstract

The invention discloses a three-frequency-based three-dimensional omnidirectional wireless electric energy transmission system, which relates to the technical field of wireless electric energy transmission and comprises a direct-current power supply, three high-frequency inverters, three transmitting coils, three planar single-pole receiving coils, a planar single-pole load coil, a rectifier and a load. The three transmitting coils are orthogonally arranged and have different resonant frequencies, the three receiving coils and the load coil are located on the same plane, and the load coil surrounds the three receiving coils and is inductively coupled with the three receiving coils; each high-frequency inverter is connected with a direct-current power supply and a corresponding transmitting coil, the three receiving coils are respectively in resonant coupling with the three transmitting coils through three frequencies, the input end of the rectifier is connected with a load coil, and the output end of the rectifier is connected with a load. The device is suitable for simultaneous charging of multiple devices, transmission is stable, and practicability is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless power transmission, in particular to a three-dimensional omnidirectional wireless power transmission system based on three frequencies. BACKGROUND

[0002] With the popularity of consumer electronics and the development of Internet of Things technology, the demand for wireless charging that can simultaneously charge multiple devices and in a random moving state of the devices is increasing. Currently, the mainstream wireless charging technology is mostly based on inductive coupling or magnetic coupling resonance principle, and its typical working mode is one-to-one directional transmission. This mode requires the transmitting end and the receiving end coils to be closely adjacent and strictly aligned, which greatly limits the freedom of device placement and use convenience, making it difficult to adapt to future multi-device collaborative and dynamic charging application scenarios. In order to overcome the limitations of directional transmission, three-dimensional omnidirectional wireless power transmission technology has emerged, which aims to form a three-dimensional, uniform energy transmission area around the transmitting end, allowing the receiving end to stably obtain power at any position and direction within the area.

[0003] In the prior art, in order to achieve omnidirectional power transmission, researchers have proposed various schemes. Among them, using three orthogonal coils to form a transmitter is a relatively typical structure. For example, some existing invention patents generate a combined magnetic field through three sets of orthogonally arranged transmitting coils in order to achieve energy coverage in the entire space. However, such a three-coil orthogonal system based on single-frequency driving will form a ring-shaped magnetic field distribution inside. This ring-shaped magnetic field characteristic causes the magnetic flux to not be able to effectively pass through the receiving coil in certain spatial poses when it is coupled with a planar monopole receiving coil that is simple in structure and easy to integrate into a thin device, thereby forming an energy transmission blind area, making wireless power transmission impossible. To address this problem, two main improvement paths have emerged in the prior art: one is to introduce complex control circuits and real-time algorithms to dynamically adjust system parameters to track the optimal transmission state, but this significantly increases the complexity and cost of system design; the other is to design special transmitting or receiving coils with non-planar, three-dimensional structures, but this occupies too much internal space of the device, which is not conducive to application in space-sensitive consumer electronics.

[0004] In summary, the three-dimensional omnidirectional wireless power transmission system in the prior art, especially the scheme based on three orthogonal coils, generally has the problem of energy transmission blind area caused by ring-shaped magnetic field when facing the widely used planar monopole receiving coil. The current solutions to this blind area problem either introduce complex control and algorithms, increasing the system complexity and cost, or use special coil structures that occupy too much space, reducing the practicality and universality of the technology. This has become a key obstacle to the large-scale commercial application of omnidirectional wireless power transmission technology. SUMMARY

[0005] The present application aims at solving the problems of the prior art, and provides a three-dimensional omnidirectional wireless power transmission system based on three frequencies, which comprises a direct-current power supply, three high-frequency inverters, three transmitting coils, three planar monopole receiving coils, a planar monopole load coil, a rectifier and a load.

[0006] The present application aims at solving the problems of the prior art, and provides a three-dimensional omnidirectional wireless power transmission system based on three frequencies, which comprises a direct-current power supply, three high-frequency inverters, three transmitting coils, three planar monopole receiving coils, a planar monopole load coil, a rectifier and a load. The three transmitting coils are arranged orthogonally, and the resonant frequencies of the three transmitting coils are different from each other. The three receiving coils are mutually decoupled, the load coil surrounds the three receiving coils, and the three are in the same plane with the load coil, and the load coil is inductively coupled with the three receiving coils. The input end of each high-frequency inverter is connected with the direct-current power supply, and the output end of each high-frequency inverter is connected with one transmitting coil. The three receiving coils and the three transmitting coils are resonantly coupled through three frequencies, respectively. The input end of the rectifier is connected with one load coil, and the output end of the rectifier is connected with the load.

[0007] Further, the transmitting coil is a square coil, and the orthogonal arrangement of the three square transmitting coils makes the mutual inductance effect between adjacent transmitting coils negligible. The receiving coil is a square coil, and the structure of the three square receiving coils is adapted to that of the three square transmitting coils, and the winding directions of the three square receiving coils are consistent.

[0008] Further, the size ratio of each receiving coil to each transmitting coil is in the range of 0.1 to 0.43, and the size ratio between any two receiving coils is less than 0.82, so as to realize the overlapping decoupling of the three receiving coils.

[0009] Further, the mutual inductance coefficient between the transmitting coil and the receiving coil is calculated by the following formula:

[0010] wherein, represents the vacuum permeability, represents the wire length microelement of the transmitting coil, The infinitesimal element representing the length of the wire in the receiving coil. Indicates the infinitesimal element of the wire length With the infinitesimal element of the wire length The spacing between them Indicates the number of coil turns. This represents the total length of the wire path leading to the transmitting coil. This indicates the total length of the wire path for the receiving coil.

[0011] Furthermore, each transmitting coil is connected to its corresponding high-frequency inverter via an LCC-S compensation network; The LCC-S compensation network is used to enable the system to resonate at the resonant frequency of the corresponding transmitting coil, and the input voltage and input current have zero phase angle at the resonant frequency. In the system resonant state, the parasitic resistance of the transmitting and receiving coils has a negligible effect on the input impedance calculation, and the load coil is not in a resonant state.

[0012] Furthermore, the high-frequency inverter is of the type of full-bridge inverter, half-bridge inverter, or Class E inverter; The rectifier is either a diode rectifier or a synchronous rectifier. The output voltages of the three high-frequency inverters are the excitation voltages of their respective transmitting coils, and the output voltage of the rectifier is the supply voltage of the load.

[0013] Furthermore, the three receiving coils are wound in the same direction, and the length of the overlapping part of the three receiving coils is 0.01 times the side length of the receiving coil; The total area of ​​the three receiving coils is slightly smaller than the area of ​​a single transmitting coil; The total length of the load coil and the three receiving coils is the same as the side length of the transmitting coil to ensure consistent coupling between the load coil and the three receiving coils.

[0014] Furthermore, the system's output power is calculated using the following formula:

[0015] in, Indicates the first The first transmitting coil and the second Mutual inductance between the receiving coils Indicates the first The angular frequency corresponding to the resonant frequency of each transmitting coil Indicates the first The capacitance parameters of the LCC-S compensation network corresponding to each transmitting coil. Indicates the first The internal resistance of each receiving coil This indicates the resistance value of the load. The values ​​of 1, 2, and 3 correspond to the transmitting and receiving coils at three different resonant frequencies.

[0016] Furthermore, the system's transmission efficiency is calculated using the following formula:

[0017] in, This indicates the resistance value of the load. This indicates the internal resistance of the load coil. Indicates the first The angular frequency corresponding to the resonant frequency of each transmitting coil The values ​​of 1, 2, and 3 correspond to three different resonant frequencies of the transmitting coil.

[0018] Furthermore, the three transmitting coils can operate individually or in any combination simultaneously; As the receiving coil moves with the load, the coupling coefficient between the receiving coil and the transmitting coil increases as the edges of the receiving coil and the transmitting coil get closer together. By coordinating three orthogonally arranged transmitting coils with three decoupled receiving coils, the system achieves three-dimensional omnidirectional wireless power transmission without charging blind spots in three-dimensional space.

[0019] Compared with existing technologies, this three-dimensional omnidirectional wireless power transfer system based on three frequencies has the following advantages: I. This invention constructs a three-frequency independent energy transmission channel by setting up three orthogonally arranged transmitting coils with different resonant frequencies, three decoupled receiving coils that resonate with each transmitting coil at corresponding frequencies, and a load coil surrounding the three receiving coils and lying on the same plane. This avoids the problem of the toroidal magnetic field in a single-frequency orthogonal system preventing the magnetic flux of the planar unipolar receiving coil from effectively passing through. At the same time, the coplanar arrangement of the three receiving coils and the load coil can greatly simplify the mechanical design and integration process of the receiver, making it more suitable for the internal space constraints of thin and light consumer electronics products and reducing the installation error of non-coplanar structures. It eliminates the need for complex control circuits and real-time adjustment algorithms, as well as the need for non-planar special coil structures, thereby realizing wireless power transmission without charging blind spots in three-dimensional space. This solves the problems of increasing system complexity, design costs, or occupying too much internal space in the prior art to eliminate transmission blind spots, ensuring that the receiver can stably obtain power regardless of the load's position.

[0020] Secondly, the application sets an LCC-S compensation network between each transmitting coil and the corresponding high-frequency inverter, so that the system realizes zero-phase-angle resonance at the corresponding resonance frequency, the influence of the transmitting coil and the receiving coil parasitic resistance on the input impedance calculation can be ignored, the structure adaptability and size ratio relationship of the receiving coil and the transmitting coil are optimized, and the coupling efficiency between the coils is improved; the rectifier input end is connected with the load coil instead of being directly connected with the three receiving coils, so that the rectifier input wiring complexity can be reduced, mutual interference of the multi-frequency signals before rectification can be avoided, and circuit loss is further reduced; in addition, the three transmitting coils can work independently or work simultaneously in any combination, which can adapt to the simultaneous charging demand of multiple different types of consumer electronic products, without the need to adjust the system core structure for different devices, the application threshold in the multi-device dynamic charging scene is reduced, the practicability and energy transmission efficiency of the system are further improved, and the large-scale application demand in the consumer electronics and Internet of Things fields can be better met.

[0021] Additional advantages, objects, and features of the application will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following specification or can be learned by practice of the application. The objects and advantages of the application can be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating laborious work on the basis of these drawings.

[0023] Figure 1 It is a system structure schematic diagram of the present application; Figure 2 It is an operation flow schematic diagram of the present application; Figure 3 It is a coupling coil schematic diagram of the present application; Figure 4 It is a circuit schematic diagram of the present application; Figure 5 It is an equivalent circuit schematic diagram of the present application; Figure 6 It is a simplified equivalent circuit schematic diagram of the present application; Figure 7 It is a mutual inductance coefficient calculation result schematic diagram of the present application; Figure 8 It is a mutual inductance coefficient calculation result schematic diagram of the present application; Figure 9 It is a mutual inductance coefficient schematic diagram of different coupling coils under varying coupling distances of the present application; Figure 10 This is a schematic diagram of the a-frequency coupler structure of the present invention; Figure 11 This is a schematic diagram of the b-band three-frequency coupler structure of the present invention; Figure 12 This is a schematic diagram illustrating how the performance of the present invention changes with variable load; Figure 13 This is a schematic diagram illustrating the transmission performance of different coupling coils in two tracks according to the present invention; Figure 14 This is a schematic diagram illustrating the transmission performance of different coupled coils in two tracks according to the present invention. Detailed Implementation

[0024] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0025] Example 1 like Figure 1 As shown, this embodiment is based on a three-dimensional omnidirectional wireless power transmission system based on three frequencies disclosed in this invention. Through specific structural design, parameter matching and performance verification, it fully presents the implementation process of the system, ensuring that those skilled in the art can reproduce the technical solution of this invention based on this embodiment.

[0026] This embodiment of the three-frequency-based three-dimensional omnidirectional wireless power transfer system mainly consists of a DC power supply, three high-frequency inverters, three transmitting coils, three planar monopole receiving coils, one planar monopole load coil, a rectifier, and a load. The connections and functional divisions of each component are clearly defined, working together to achieve omnidirectional and stable wireless power transfer in three-dimensional space, as detailed below: The DC power supply serves as the energy input source for the system, providing a stable DC voltage for the entire system. Its output is simultaneously connected to the input of three high-frequency inverters, ensuring that all three inverters can obtain a continuous power supply. Each high-frequency inverter's output terminal is connected to a corresponding transmitting coil. The core function of the inverter is to convert the DC power input into a high-frequency AC power of a specific frequency. The high-frequency AC power output by the three inverters is different from each other, and is matched with the resonant frequency of the three transmitting coils respectively. The three transmitting coils are arranged orthogonally to form a three-dimensional energy radiation structure. The three receiving coils and the three transmitting coils achieve resonant coupling through three different frequencies. The load coil surrounds the three receiving coils and forms inductive coupling with them. The input end of the rectifier is connected with a load coil, which is used to convert the high-frequency alternating current transmitted by the load coil into direct current. The output end of the rectifier is connected with the load, and finally provides stable direct current power supply for the load.

[0027] Transmit coil design: In this embodiment, the transmit coil adopts a square coil structure. The reason for choosing a square coil is that, through comparison of the mutual inductance variation law of circular coils and square coils, it is found that the mutual inductance stability and effective value of square coil combination are better than those of circular coil combination, especially in the commonly used transmission distance range of 1 to 1.5 times the coil radius, the mutual inductance value of square coil combination is obviously higher than that of circular coil combination, and the square coil can accommodate more magnetic lines through the coil interior, which is conducive to improving the coupling efficiency.

[0028] The three square transmit coils are arranged in an orthogonal manner, i.e., the three coils are arranged along the X-axis, Y-axis and Z-axis directions of the three-dimensional space respectively, and the spatial positional relationship between adjacent coils satisfies the condition that the mutual inductance effect can be ignored. This orthogonal arrangement design can cover all directions of the three-dimensional space on the one hand, laying a structural foundation for omnidirectional energy transmission; on the other hand, the weakening of the mutual inductance effect between adjacent coils can avoid frequency crosstalk caused by magnetic field interference between different transmit coils, ensuring that each transmit coil can work stably at its own resonant frequency.

[0029] The resonant frequencies of the three transmit coils are different, which are determined by the inductance of the coils and the parameters of the compensation network. Since the three transmit coils have the same structure and size, their inductances are basically the same, so the difference in resonant frequencies of the three transmit coils is mainly realized by adjusting the capacitance parameters in the LCC-S compensation network described later. The selection of the three frequencies should avoid mutual interference to ensure that each frequency corresponds to an independent and stable energy transmission channel.

[0030] Receive coil design: The three receive coils and a load coil all adopt square coil structures, and the three mutually decoupled receive coils and the load coil are in the same plane, which is adapted to the square structure of the transmit coil, ensuring higher magnetic field matching degree in the coupling process and reducing energy loss caused by structural mismatch; the load coil surrounds the three receive coils and is inductively coupled with the three receive coils.

[0031] The design of the three receiving coils needs to meet two core requirements: one is to achieve mutual decoupling, and the other is to form efficient resonant coupling with the corresponding transmitting coil. To achieve mutual decoupling, the size ratio of each receiving coil to each transmitting coil needs to be strictly controlled: the size ratio of each receiving coil to each transmitting coil is within the range of 0.1 to 0.43, and the size ratio between any two receiving coils is less than 0.82. Experimental verification shows that when the size ratio of the receiving coil to the transmitting coil exceeds the range of 0.1 to 0.43, the magnetic field strength induced by the receiving coil will be significantly reduced, resulting in a decrease in transmission power; when the size ratio of two receiving coils is higher than 0.82, the positive mutual inductance generated by the horizontal double side will cancel out the negative mutual inductance generated by the vertical double side adjacent to it, which cannot achieve overlapping decoupling, and further causes signal interference between coils.

[0032] In addition, the three receiving coils are wound in the same direction, and the length of the overlapping part accounts for 0.01 times the side length of the receiving coil. The same direction winding can ensure that the induced current directions of the three receiving coils are consistent when they are in the magnetic field, avoiding the cancellation of induced electromotive force due to opposite winding directions; controlling the length of the overlapping part can not only reduce the occupied space of the receiving coil in the plane, but also further weaken the mutual inductance interference between coils. At the same time, the total area of the three receiving coils is slightly smaller than the area of a single transmitting coil, and this size design can ensure that the magnetic field radiated by the transmitting coil can fully cover the three receiving coils, improving the coupling efficiency.

[0033] The design of the load coil needs to match the layout of the three receiving coils: the load coil is arranged around the three receiving coils, and the total length of the load coil combined with the three receiving coils is consistent with the side length of the transmitting coil. The purpose of this design is to ensure that the coupling distance between the load coil and the three receiving coils is uniform, avoiding uneven energy distribution caused by differences in coupling distance, and ensuring that the energy induced by the three receiving coils can be efficiently transmitted to the load coil.

[0034] High-frequency inverter and rectifier design: In this embodiment, the high-frequency inverter uses an E-class inverter. Compared with full-bridge inverters and half-bridge inverters, the E-class inverter has higher conversion efficiency, especially in high-frequency working scenarios, its switching loss is lower, which can reduce the loss of electrical energy in the inverter process and improve the overall energy efficiency of the system. The circuit structure of the three E-class inverters is consistent, and only by adjusting the control signal frequency of the internal switch tube, the difference of the output high-frequency alternating current frequency is realized, which respectively matches the resonant frequencies of the three transmitting coils, and the output voltages of the three inverters are used as the excitation voltages of the corresponding transmitting coils, and their amplitudes can be adjusted according to the power demand of the load.

[0035] The rectifier is a synchronous rectifier. Compared with a diode rectifier, the synchronous rectifier has a lower conduction voltage drop, which can reduce the loss in the process of converting alternating current into direct current. The input end of the synchronous rectifier is connected to three receiving coils through wires. The control circuit inside the synchronous rectifier can dynamically adjust the conduction and turn-off timing of the rectifier tube according to the phase and amplitude of the alternating current output by the three receiving coils, so as to efficiently convert the high-frequency alternating current output by the three receiving coils into direct current. The output voltage of the rectifier is the power supply voltage of the load, and the stability of the output voltage is further optimized by the filter circuit inside the rectifier.

[0036] LCC-S compensation network design: An LCC-S compensation network is arranged between each transmitting coil and the corresponding high-frequency inverter. The core function of the compensation network is to make the system resonate at the resonant frequency of the corresponding transmitting coil, and the input voltage and input current present a zero phase angle in the resonant state, thereby improving the transmission performance of the system.

[0037] The LCC-S compensation network is composed of inductors and capacitors, and the specific parameters are determined according to the resonant frequency of the corresponding transmitting coil. By adjusting the capacitance and inductance values in the compensation network, the loop formed by the compensation network, the transmitting coil and the receiving coil satisfies the resonance condition at the target frequency. When the system is in the resonant state, the influence of the parasitic resistance of the transmitting coil and the receiving coil on the input impedance calculation can be ignored, and at this time the input impedance of the loop is mainly determined by the inherent parameters of the compensation network and the coil, which is beneficial to reduce the influence of parasitic parameters on the transmission efficiency.

[0038] It should be particularly noted that the load coil is not in the resonant state. Since the load coil needs to form inductive coupling with three receiving coils at the same time, if the load coil is tuned to a certain frequency, it will cause the coupling efficiency with other frequency receiving coils to decrease, so the load coil is not tuned to the resonant state during design, but energy transmission is realized through inductive coupling to ensure the coupling compatibility of the three receiving coils.

[0039] System workflow: The three-frequency-based three-dimensional omnidirectional wireless power transmission system of the embodiment has a working process that can be divided into four stages: energy conversion, energy radiation, energy coupling and energy rectification, which are as follows: Energy conversion stage: The direct current output stable direct current is input to three high-frequency inverters respectively. The three high-frequency inverters convert the input direct current into high-frequency alternating current of three different frequencies according to the preset control signal. Among them, the first inverter outputs high-frequency alternating current of frequency f1, matching the resonance frequency of the first transmitting coil; the second inverter outputs high-frequency alternating current of frequency f2, matching the resonance frequency of the second transmitting coil; the third inverter outputs high-frequency alternating current of frequency f3, matching the resonance frequency of the third transmitting coil. The conversion process of the three inverters is synchronous, and the amplitude of the output high-frequency alternating current remains stable, ensuring the stability of the subsequent energy radiation.

[0040] Energy radiation stage: The high-frequency alternating current output by the three high-frequency inverters is input to the corresponding LCC-S compensation network, and the compensation network adjusts the phase and amplitude of the high-frequency alternating current, so that the current and voltage input to the transmitting coil meet the resonance condition. The three transmitting coils generate alternating magnetic fields under the excitation of high-frequency alternating current. Since the three transmitting coils are arranged orthogonally, the alternating magnetic fields generated by them superimpose in three-dimensional space to form an omnidirectional magnetic field radiation area covering the X-axis, Y-axis and Z-axis directions, realizing energy distribution in three-dimensional space.

[0041] Energy coupling stage: When the receiving coil moves with the load in three-dimensional space, the three receiving coils respectively resonate with the three transmitting coils through corresponding frequencies: the first receiving coil only resonates with the transmitting coil of frequency f1 to induce high-frequency alternating current of frequency f1; the second receiving coil only resonates with the transmitting coil of frequency f2 to induce high-frequency alternating current of frequency f2; the third receiving coil only resonates with the transmitting coil of frequency f3 to induce high-frequency alternating current of frequency f3. Since the three receiving coils are decoupled from each other, they will not interfere due to frequency differences.

[0042] At the same time, the load coil forms an inductive coupling with the three receiving coils, and the high-frequency alternating current induced by the three receiving coils is transmitted to the load coil through inductive action. The load coil combines the energy of the three receiving coils to form a unified energy output. It should be noted that when the receiving coil moves with the load, the coupling coefficient of the receiving coil and the transmitting coil will increase as the edges of the receiving coil and the transmitting coil approach: when the edges are closest, the coupling coefficient reaches a maximum value, at which point the energy transmission efficiency is highest; when the edges are far apart, the coupling coefficient decreases, but due to the orthogonal arrangement of the three transmitting coils and the frequency matching of the three receiving coils, at least one receiving coil can still maintain effective coupling with the corresponding transmitting coil, avoiding the occurrence of an energy transmission blind area.

[0043] Energy rectification stage: Three receiving coils transmit energy to the load coil in the same plane by inductive coupling, the high-frequency alternating current output by the load coil is input to the rectifier, and the rectifier converts the high-frequency alternating current into stable direct current through the internal switch tube and filter circuit. The direct current output by the rectifier directly supplies the load, providing continuous and stable power for the load, completing the entire wireless power transmission process.

[0044] Mutual inductance calculation: The mutual inductance between the transmitting coil and the receiving coil is a key parameter that affects the transmission performance of the system. The mutual inductance between the transmitting coil and the receiving coil is calculated by the following formula:

[0045] Wherein, represents the vacuum permeability, represents the wire length microelement of the transmitting coil, represents the wire length microelement of the receiving coil, represents the wire length microelement and the distance between the wire length microelement , represents the number of turns, represents the total wire length path of the transmitting coil, represents the total wire length path of the receiving coil.

[0046] In the actual calculation process, since the transmitting coil and the receiving coil in the embodiment are both square, the calculation can be simplified by combining the parameter equation of the square coil: the total wire length path of the square coil and can be determined according to the side length of the square coil, the wire length microelement and are distributed along the edges of the square coil, and the distance is determined according to the spatial position of the transmitting coil and the receiving coil. At the same time, experimental verification shows that the number of turns only changes the size of the mutual inductance, but does not affect the change trend of the mutual inductance. Therefore, the transmitting coil and the receiving coil in the embodiment are designed as single turns, which simplifies the calculation process while ensuring stable transmission performance.

[0047] Optimization of coil parameters: Based on the above mutual inductance calculation formula, the size parameters of the receiving coil are optimized, and the size ratio of the three receiving coils to the transmitting coil is finally determined as 0.4, 0.32 and 0.256. The basis for selecting the ratio is as follows: Firstly, the ratio range is within the design requirement of 0.1 to 0.43, ensuring the coupling efficiency of the receiving coil and the transmitting coil; Secondly, the ratio between any two receiving coils is less than 0.82, which satisfies the condition for overlap decoupling; Finally, through experimental testing, it was found that the mutual inductance coefficients of the three receiving coils changed smoothly at this ratio, and the fluctuation amplitude of the mutual inductance coefficients was less than 5% when rotating in three-dimensional space, ensuring the stability of the transmitted power.

[0048] Furthermore, the overlap length of the three receiving coils is 0.01 times the side length. This design has been experimentally verified: when the overlap length exceeds 0.01 times the side length, the mutual inductance interference between the receiving coils increases significantly; when the overlap length is less than 0.01 times the side length, the planar space occupied by the receiving coils increases significantly, which is not conducive to integration into small consumer electronics products. Therefore, an overlap length of 0.01 times the side length is the optimal balance between space occupation and mutual inductance interference.

[0049] Transmission performance calculation formula: The system output power and transmission efficiency in this embodiment are calculated using the following formulas to ensure the objectivity and accuracy of the performance analysis: Output power calculation formula:

[0050] in, Indicates the first The first transmitting coil and the second Mutual inductance between the receiving coils Indicates the first The angular frequency corresponding to the resonant frequency of each transmitting coil Indicates the first The capacitance parameters of the LCC-S compensation network corresponding to each transmitting coil. Indicates the first The internal resistance of each receiving coil This indicates the resistance value of the load. The values ​​of 1, 2, and 3 correspond to the transmitting and receiving coils at three different resonant frequencies.

[0051] As shown in the formula, the system output power is directly proportional to the sum of the mutual inductance coefficients of the three transmitting and receiving coils. Therefore, ensuring the stability of the sum of the three mutual inductance coefficients is crucial for achieving stable output power. In this embodiment, the orthogonal arrangement of the three transmitting coils and frequency matching with the three receiving coils ensure that the fluctuation amplitude of the sum of the three mutual inductance coefficients is less than 8% when the receiving coil moves to any position in three-dimensional space, thus guaranteeing the stability of the output power.

[0052] Transmission efficiency calculation formula:

[0053] in, a resistance value of the load, an internal resistance of the load coil, an angular frequency corresponding to the resonant frequency of the first transmitting coil, The value of k is 1, 2, 3, respectively corresponding to the transmitting coil of three different resonant frequencies.

[0054] It can be seen from the formula that the system transmission efficiency is proportional to the load resistance and inversely proportional to the internal resistance of the load coil and the angular frequency. Therefore, the transmission efficiency can be improved in two ways: one is to increase the load resistance, and the other is to reduce the internal resistance of the load coil. In this embodiment, the load resistance is selected as 50Ω, and the experimental verification shows that the system transmission efficiency can reach more than 85% under this load resistance; at the same time, the load coil uses high-conductivity copper wire to reduce the internal resistance of the load coil and further improve the transmission efficiency.

[0055] Experimental verification results: To verify the transmission performance of the system in this embodiment, an experimental platform is built to test the no-charging blind area characteristics, transmission power stability and transmission efficiency of the system, and the specific results are as follows: No-charging blind area verification: Two typical trajectories are selected for moving test of the receiving coil: trajectory Z is rotating around the transmitting coil along the Z-axis direction, and trajectory X is rotating around the transmitting coil along the X-axis direction. The experiment shows that on the trajectory Z, the system allows two transmitting coils to work at the same time, the transmission performance has an extreme point, but the transmission power at the extreme point remains more than 92% of the rated power; on the trajectory X, three transmitting coils supply power at the same time, the transmission performance curve is smoother, and the power fluctuation amplitude is less than 5%. The test results of the two trajectories show that there is no transmission power drop in any position in the three-dimensional space, proving that the system realizes true three-dimensional omnidirectional wireless power transmission without charging blind area.

[0056] Transmission power stability verification: Ten different positions are selected in the three-dimensional space to test the output power of the system at each position. The experimental results show that the difference between the maximum and minimum output power of the 10 positions is 7.5% of the rated power, which meets the requirements of power stability in the multi-device random movement scene, proving that the transmission power stability of the system is excellent.

[0057] Transmission efficiency verification: Under the conditions of a load resistance of 50Ω and a coupling distance of 1 times the coil radius, the transmission efficiency of the system under different rotation angles is tested. The experimental results show that the maximum transmission efficiency of the system is 87.2%, the minimum transmission efficiency is 82.3%, and the average transmission efficiency is 84.8%. Compared with the traditional single-frequency orthogonal system, the transmission efficiency of the system in this embodiment is obviously improved.

[0058] Other variant embodiments are described as follows: In addition to the above embodiments, the application can also be designed as follows, and all belong to the protection scope of the application: The high-frequency inverter can be replaced by a full-bridge inverter or a half-bridge inverter, which has slightly lower conversion efficiency than the E-class inverter, but can still meet the power supply requirements of medium and low power loads; The rectifier can be replaced by a diode rectifier, which has slightly higher conduction loss, but simpler circuit structure and lower cost, suitable for cost-sensitive application scenarios; The size ratio of the transmitting coil and the receiving coil can be adjusted within the range of 0.1 to 0.43 according to the actual load requirements, as long as the size ratio of any two receiving coils is less than 0.82, which can realize overlapping decoupling.

[0059] In summary, through clear structural design, parameter matching and experimental verification, the implementation process of the three-dimensional omnidirectional wireless power transmission system based on three frequencies is fully presented, the problems of poor universality, existence of charging blind area and high system complexity of the traditional wireless power transmission system are solved, and the demand for simultaneous three-dimensional omnidirectional wireless power transmission of multiple different size consumer electronic products can be met, which has significant practicality and advancement.

[0060] Embodiment two This embodiment optimizes the defects of the traditional single-frequency orthogonal three-dimensional omnidirectional wireless power transmission system. The traditional system has a transmission blind area due to the annular magnetic field of the planar monopole receiving coil, and the existing solution requires complex control circuit or large volume coil, which increases the cost and system complexity. The system of this embodiment includes a DC power supply, three high-frequency inverters, three orthogonally arranged square transmitting coils, three planar square receiving coils, one square load coil and one rectifier. The three mutually decoupled receiving coils and the load coil are in the same plane, the load coil surrounds the three receiving coils and is inductively coupled with them, and the input end of the rectifier is connected to the load coil. Through the LCC-S compensation network, zero phase angle resonance is realized under each frequency, the size ratio of the receiving coil to the transmitting coil is controlled to be 0.4, 0.32 and 0.256, and the size ratio between the receiving coils is less than 0.82 to realize decoupling, so that three-dimensional wireless power transmission without blind area can be realized without the need for control circuit, and the stability of transmission power and efficiency is guaranteed.

[0061] As Figure 4As shown, the system includes a DC power supply, a class-E inverter, a LCC-S compensation network, a coupling coil, a full-bridge rectifier and a load. The coupling coil is composed of a transmitting coil, three mutually decoupled receiving coils and a load coil. The load coil is inductively coupled with the three receiving coils. The input of the rectifier is connected to the load coil, realizing the energy transfer from the load coil to the rectifier. The inductance of the load coil, the three receiving coils and the rectifier are denoted as LTi, LRi and LL, respectively. Udc, UIni, IIni, ITi, IRi and IL represent the DC bus voltage, the inverter output voltage, the transmitting coil current, the receiving coil current and the relay coil current, respectively. RTi, RRi and RL represent the transmitting coil resistance, the receiving coil resistance and the relay coil resistance, respectively.

[0062] The three transmitters operate at three different frequencies: f1, f2 and f3, respectively. Correspondingly, the receiver contains voltage components of fi, but the resonance frequency of each Rxi is fi. Since the tightly wound Rxs-Lx produces detuning when resonating, the inductor Lx is not tuned to the resonant state. In addition, Lx needs to be coupled with the three Rxs simultaneously, so it cannot maintain the resonant state, and therefore they are connected through inductive coupling. Through this design, a single Lx can be coupled with three Rxs arranged in the plane, while eliminating the mutual inductance between overlapping Rxs. The three transmitters are arranged orthogonally, and their mutual inductive effect can also be ignored.

[0063] As shown in Figure 5 , the equivalent circuit of the system is shown, where MTiRj and MRiL represent the mutual inductance between the transmitter-receiver and the receiver-Lx, respectively. The size of the transmitter is comparable to Lx, but larger than the receiver.

[0064] (1) where, Udc, UIni, IIni, ITi, IRi and IL represent the DC bus voltage, the inverter output voltage, the transmitting coil current, the receiving coil current and the relay coil current, respectively. RTi, RRi and RL represent the transmitting coil resistance, the receiving coil resistance and the relay coil resistance, respectively. , , , , , , , , , , , , , These represent the mutual inductance coefficients between the transmitter and the load, and between the receiver and the load, respectively. For the angular frequency of each coil, The equivalent impedance is given. The compensation network is designed to achieve resonance, that is, to make the input voltage Vin and the input current Iin have zero phase angle at the fi frequency, thereby improving the system's transmission performance. When the system resonates, the effect of parasitic resistance on the input impedance calculation is negligible. and However, the Lx branch did not resonate, therefore Therefore, it is possible to make Based on the assumptions made, a simplified equivalent circuit for this system is obtained.

[0065] like Figure 6 As shown, equation (1) can be simplified to: (2) in, , This represents the mutual inductance between the transmitting and receiving coils. This indicates the impedance of the receiving coil. and These represent the mutual inductance coefficients between the receiving coil and the load, respectively. The subscripts i=k=1,2,3 are used to distinguish different coils. All other parameters in the formula remain consistent with equation (1). Based on equation (2), the following can be derived: , , The expression is as follows: (3) (4) (5) (6) The current is proportional to several parameters, such as the operating frequency, mutual inductance coefficient, and compensation network parameters. However, the main focus of this system is on output power and transmission efficiency, so only equations (3) and (6) need to be calculated.

[0066] Transmission performance: The transmission performance of the tri-band WPT system is calculated using formulas (3) and (6). Its output power can be expressed as: (7) From equation (7), it can be concluded that: when the system is running, only It is changing, and the output power is... The sum is directly proportional. Therefore, it is necessary to maintain... The sum of the three is stable to obtain stable output power. But as described in Section III, in the single-frequency quadrature system, when the planar monopole receiver moves around the transmitter, The sum of the three is not stable, but the three-frequency system proposed in this embodiment can avoid related problems. Next, the transmission efficiency can be obtained: (8) As can be seen from equation (8), the efficiency is only related to the impedance of Lx and the load, and the system frequency is inversely proportional to the transmission efficiency. If the load is increased, the transmission efficiency will be improved.

[0067] In summary, only the in equation (7) is related to the stability of the transmission power, and the remaining parameters are used to adjust the size of the output power. In addition, equation (8) indicates that improving the transmission efficiency can be achieved by increasing the load or reducing the high-frequency inductance Lx. Both can be adjusted. But the change of is unpredictable. As can be seen from the above analysis, the is the key requirement for transmission performance, which means that the mutual inductance between the transmitting end and the receiving end must be stable and high.

[0068] The mutual inductance coefficient of the transmitting coil and the receiving coil: Since there are many forms of mutual inductance coefficients, and in order to reflect the rotation characteristics of the system in three-dimensional space, the mutual inductance coefficient is calculated according to the physical structure and spatial position of the coupled coils: (9) where, is the vacuum permeability, is the length element of the wire, is the distance between the two length elements, and Ni represents the number of turns of the coil. As can be seen from equation (9), the mutual inductance of Rx coils with different structures and positions is different, which affects the transmission performance. The commonly used coil structures at present are mainly circular and square, because of their simple structure, easy to process, and convenient to install inside the space sensitive device. Therefore, this embodiment focuses on the analysis of the above two structures.

[0069] The parametric equation expression of the circular coil in three-dimensional space is: (10) where (x, y, z) represents the coordinates of the center of the coil, R represents the radius of the coil, and δ and ζ represent the parameters of the coil. According to equation (10), the position of any circular coil in three-dimensional space can be calculated as follows: And the parametric expression of the square coil in three-dimensional space is: (11) where the line vector represents the wire starting point coordinates (x, y, z) and t is the wire parameter variable. The mutual inductance coefficient changes due to the change of the coupling coil physical structure and spatial position. Equations (10) and (11) have completed the modeling of the coil structure, while the rotation formula can describe the spatial pose change. The rotation matrix around the x-axis, y-axis, and z-axis can be represented as: (12) where, , and represent the rotation angle around the x-axis, y-axis, and z-axis, respectively. We selected two regular coils and calculated their mutual inductance coefficients when they rotated in three-dimensional space. Mathematical models were established for two common coil structures, and the variation law of mutual inductance coefficients during three-dimensional space rotation was calculated using equations (9)–(12). The relevant formulas include: mutual inductance between circular coils, mutual inductance between circular coils and square coils, mutual inductance between square coils.

[0070] (13) where,

[0071]

[0072]

[0073] Subscript 0 represents Tx, and subscript 1 represents Rx.

[0074] (14)

[0075]

[0076]

[0077] Subscript 0 represents Tx, and subscript 1 represents Rx.

[0078] (15) where,

[0079]

[0080]

[0081] Subscript 0 represents Tx, and subscript 1 represents Rx.

[0082] like Figure 7 and Figure 8 As shown, a represents a large square coil and a circular coil, and b represents a small square coil and a circular coil. Except for the large square coil (cs), the mutual inductance curves for the other eight types all exhibit a valley shape. The mutual inductance value should gradually decrease during rotation from 0° to 90°, but as the coil edges approach each other, the circular magnetic field gradually participates in coupling. The formation of the two peaks is the result of the combined effect of the linear magnetic field and the circular magnetic field. In summary, the stability and effective value of the mutual inductance between square coils are superior to those involving circular coils. Therefore, in this embodiment, a square coil is ultimately chosen as the coupling coil.

[0083] like Figure 9 As shown, the SS(B) type coil has the highest mutual inductance, followed by the CC type and the SS(S) type. With increasing coupling distance, especially within a transmission distance range of 1 to 1.5 times the radius, the mutual inductance of the SS(B) and SS(B45) combinations is significantly better than other coupled coils, and the mutual inductance values ​​of these two combinations are roughly equivalent. Therefore, under conditions of increasing transmission distance, the square coil remains the best choice for coupled coils. This is because, at the same coupling distance, the area of ​​a square coil is larger than that of a circular coil, allowing more magnetic lines of force to pass through the coil's interior. Through a comprehensive analysis of the changes in coupling angle and coupling distance, this embodiment concludes that, in terms of the mutual inductance variation law, the mutual inductance coefficient performance of the square coil is superior to that of the circular coil.

[0084] In some implementations, overlapping decoupling cannot be achieved when the ratio of the coupling coils is between 1 and 0.82. This is because the reverse mutual inductance generated by adjacent vertical sides is canceled out by the positive mutual inductance of the horizontal sides. As the ratio decreases, the spacing between the horizontal sides gradually increases, resulting in insufficient positive mutual inductance to cancel out the reverse mutual inductance. Therefore, the prerequisite for achieving overlapping decoupling is that the ratio of the coupling coils must be below 0.82.

[0085] The ratio of the receiving coil to the transmitting coil needs to be controlled within the range of 0.1 to 0.43, and the ratio between the receiving coils needs to be lower than 0.82 to achieve overlapping decoupling. Measurements showed that the ratios of the three receiving coils to the transmitting coil were 0.4, 0.32, and 0.256, respectively. These three receiving coils must be wound in the same direction, and the overlapping portion must occupy 0.01 times the side length under single-conductor conditions. The transmitting coil consists of three orthogonal square coils. After overlapping, the total area of ​​the three receiving coils is slightly smaller than that of the transmitting coil. The load coil needs to be combined with the three receiving coils to ensure consistent length. The structure of this three-frequency coupler is as follows: Figure 10 and Figure 11 As shown, where, Figure 10For the transmitting end, Figure 11 For the receiving end.

[0086] As Figure 12 shown, although there are individual extreme points in transmission performance as the resistance value increases, the overall trend shows a gradual improvement, which is consistent with the theoretical analysis results.

[0087] As Figure 13 and Figure 14 shown, Figure 13 Z trajectory, Figure 14 X trajectory, the trajectory Z allows at most two transmitting coils to work simultaneously, which leads to the transmission performance of the system showing extreme points when rotating around the transmitting coils. When the edges of the coupled coils are closest to each other, the system coupling coefficient reaches a maximum - at this time the edges of the square coils are close to each other, thereby improving the transmission performance. The trajectory X uses three transmitting coils to supply power simultaneously, and only one main transmitting coil works in the initial position. Since the number of coils participating in energy transmission is more than that of the trajectory Z, its transmission performance curve is relatively smoother. This performance fluctuation is mainly due to the change in the number of coupled transmitting coils. Based on the characteristics of the three-coil system, if the transmission performance needs to be improved, it can be achieved by increasing the load.

[0088] The embodiment is developed for the pain points of existing wireless energy transmission technology. The mainstream directional wireless energy transmission is in 1-to-1 mode, which has poor universality. The single-frequency orthogonal omnidirectional energy transmission system has a blind area for planar receiving coils due to the annular magnetic field. The scheme of increasing the control circuit or using complex coils will increase the design difficulty, space occupation and cost. The embodiment relies on three-frequency resonance and orthogonal coil structure. On the hardware side, it is powered by a direct current power supply, and three high-frequency inverters are connected to the transmitting coils with LCC-S compensation network. The three square transmitting coils are arranged orthogonally and have negligible mutual inductance. The three decoupling receiving coils are respectively resonantly coupled with the corresponding frequency transmitting coils. The load coil surrounds the receiving coil and is inductively coupled. The rectifier connects the receiving coil and the load to complete the energy conversion, and adapts to the simultaneous energy transmission demand of multiple consumer electronic products.

[0089] From the transmission performance, the output power is proportional to the sum of the mutual inductance coefficients of the three groups of transmitting-receiving coils. The three-frequency design avoids the fluctuation problem of the sum of the mutual inductance of the single-frequency system, ensuring power stability. The transmission efficiency is proportional to the load resistance and inversely proportional to the load coil resistance and angular frequency. Increasing the load can improve the efficiency. Experimental verification shows that the mutual inductance characteristics of the square coil are better, and the transmission performance of the trajectory Z and the trajectory X has no sudden drop point. The efficiency is optimal at a load of 50Ω, proving that the system has no charging blind area. In addition, the system does not require control circuit and algorithm, greatly reducing the design and control difficulty. The transmitting coil is simple to wind, and the receiving coil is a planar structure, reducing the manufacturing cost and the space occupation of the receiving end, and meeting the demand of wireless energy transmission of multiple devices simultaneously and randomly in different directions, and has strong practicality.

[0090] Embodiment three As Figure 2 shown, this embodiment describes the working process of the three-frequency-based three-dimensional omnidirectional wireless power transmission system in detail, and shows the complete process from energy input to load power supply through specific steps. The system realizes omnidirectional energy coverage in three-dimensional space through three independent transmission channels of different frequencies, ensuring that the receiving end can stably receive power in any position and direction.

[0091] 1. System power-on and initialization: The DC power supply is turned on, and a stable DC voltage is output to provide input power for the three high-frequency inverters.

[0092] The system self-checking is completed, and each component enters the standby state.

[0093] 2. High-frequency inverter converts power: The three high-frequency inverters are started synchronously, and respectively convert DC into high-frequency AC.

[0094] The output frequency of each inverter is different, and is respectively set as f1, f2 and f3, corresponding to the resonance frequency of the three transmitting coils.

[0095] 3. Compensation network tuning: The output end of each high-frequency inverter is connected with an LCC-S compensation network to adjust the phase and amplitude of the high-frequency AC.

[0096] The compensation network ensures that the system is in resonance state at its respective resonance frequency, and the input voltage and input current present zero phase angle, to optimize the transmission performance.

[0097] 4. Transmitting coil radiates magnetic field: The three transmitting coils generate alternating magnetic fields under the excitation of high-frequency AC.

[0098] Since the transmitting coils are arranged orthogonally, the magnetic fields superimpose in three-dimensional space to form a uniform omnidirectional radiation area.

[0099] 5. Receiving coil couples energy: The three receiving coils move with the load in three-dimensional space, and respectively receive energy through magnetic coupling resonance with the corresponding frequency transmitting coils.

[0100] Receiving coil 1 is coupled with transmitting coil 1, receiving coil 2 is coupled with transmitting coil 2, and receiving coil 3 is coupled with transmitting coil 3.

[0101] The three receiving coils are decoupled from each other to avoid mutual interference during energy transmission.

[0102] 6. Load coil aggregates energy: The load coil surrounds the three receiving coils and aggregates the energy of the three receiving coils through inductive coupling.

[0103] The load coil combines multiple frequencies of high-frequency alternating current into a unified output, which is transmitted to the rectifier.

[0104] 7. The rectifier converts electrical energy: The rectifier receives the high-frequency alternating current output by the load coil and converts it into stable direct current through internal switching tubes and filter circuits.

[0105] The rectifier output voltage is adjusted according to the load demand to ensure power supply stability.

[0106] 8. Load power supply and system operation: The direct current output by the rectifier is directly supplied to the load to achieve wireless power supply.

[0107] The system monitors the load state and coupling conditions in real time, and the three transmitting coils can work independently or in combination to maintain transmission efficiency and power stability.

[0108] 9. Dynamic adjustment and blind area avoidance: When the receiving coil position changes, the system automatically adapts to the coupling state through independent channels of three frequencies.

[0109] In three-dimensional space, at least one transmitting coil and the corresponding receiving coil maintain effective coupling, ensuring no charging blind area.

[0110] The entire workflow achieves efficient and stable three-dimensional omnidirectional wireless power transmission through multi-frequency coordination and orthogonal magnetic field design, suitable for charging scenarios with multiple devices moving randomly.

[0111] The above is only the preferred embodiment of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed as above with the preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, and any equivalent embodiments with equivalent changes and modifications made to the above embodiments based on the technical essence of the present application are still within the scope of the technical solution of the present application.

Claims

1. A three-dimensional omnidirectional wireless power transfer system based on three frequencies, characterized in that, It includes a DC power supply, three high-frequency inverters, three transmitting coils, three planar unipolar receiving coils, one planar unipolar load coil, a rectifier, and a load; The three transmitting coils are arranged orthogonally, and the resonant frequencies of the three transmitting coils are different from each other; The three receiving coils are decoupled from each other, the load coil surrounds the three receiving coils, and the three are on the same plane as the load coil. The load coil is inductively coupled to the three receiving coils. Each high-frequency inverter has a DC power supply connected to its input terminal and a transmitting coil connected to its output terminal. The three receiving coils are coupled to the three transmitting coils via three different frequency resonant couplings; The input terminal of the rectifier is connected to a load coil, and the output terminal of the rectifier is connected to the load.

2. The three-dimensional omnidirectional wireless power transfer system based on three frequencies according to claim 1, characterized in that, The transmitting coil is a square coil, and the orthogonal arrangement of the three square transmitting coils makes the mutual inductance effect between adjacent transmitting coils negligible; The receiving coil is a square coil, and the three square receiving coils are structurally compatible with the three square transmitting coils, and the winding directions of the three square receiving coils are consistent.

3. The three-dimensional omnidirectional wireless power transfer system based on three frequencies according to claim 1, characterized in that, The size ratio of each receiving coil to each transmitting coil is in the range of 0.1 to 0.43, while the size ratio between any two receiving coils is less than 0.

82.

4. The three-dimensional omnidirectional wireless power transfer system based on three frequencies according to any one of claims 1 to 3, characterized in that, The mutual inductance coefficient between the transmitting coil and the receiving coil is calculated using the following formula: in, Represents the permeability of free space. The infinitesimal element representing the length of the conductor in the transmitting coil. The infinitesimal element representing the length of the wire in the receiving coil. Indicates the infinitesimal element of the wire length With the infinitesimal element of the wire length The spacing between them Indicates the number of coil turns. This represents the total length of the wire path leading to the transmitting coil. This indicates the total length of the wire path for the receiving coil.

5. The three-dimensional omnidirectional wireless power transfer system based on three frequencies according to any one of claims 1 to 4, characterized in that, Each transmitting coil is connected to its corresponding high-frequency inverter via an LCC-S compensation network. The LCC-S compensation network is used to enable the system to resonate at the resonant frequency of the corresponding transmitting coil, and the input voltage and input current have zero phase angle at the resonant frequency. In the system resonant state, the parasitic resistance of the transmitting and receiving coils has a negligible effect on the input impedance calculation, and the load coil is not in a resonant state.

6. The three-dimensional omnidirectional wireless power transfer system based on three frequencies according to any one of claims 1 to 5, characterized in that, The high-frequency inverter is of the type of full-bridge inverter, half-bridge inverter, or Class E inverter. The rectifier is either a diode rectifier or a synchronous rectifier. The output voltages of the three high-frequency inverters are the excitation voltages of their respective transmitting coils, and the output voltage of the rectifier is the supply voltage of the load.

7. The three-dimensional omnidirectional wireless power transfer system based on three frequencies according to any one of claims 1 to 6, characterized in that, The three receiving coils are wound in the same direction, and the length of the overlapping part of the three receiving coils is 0.01 times the side length of the receiving coil; The total area of ​​the three receiving coils is slightly smaller than the area of ​​a single transmitting coil; The total length of the load coil and the three receiving coils is the same as the side length of the transmitting coil.

8. The three-dimensional omnidirectional wireless power transfer system based on three frequencies according to any one of claims 1 to 7, characterized in that, The system's output power is calculated using the following formula: in, Indicates the first The first transmitting coil and the second Mutual inductance between the receiving coils Indicates the first The angular frequency corresponding to the resonant frequency of each transmitting coil Indicates the first The capacitance parameters of the LCC-S compensation network corresponding to each transmitting coil. Indicates the first The internal resistance of each receiving coil This indicates the resistance value of the load. The values ​​of 1, 2, and 3 correspond to the transmitting and receiving coils at three different resonant frequencies.

9. The three-dimensional omnidirectional wireless power transfer system based on three frequencies according to any one of claims 1 to 8, characterized in that, The system's transmission efficiency is calculated using the following formula: in, This indicates the resistance value of the load. This indicates the internal resistance of the load coil. Indicates the first The angular frequency corresponding to the resonant frequency of each transmitting coil The values ​​of 1, 2, and 3 correspond to three different resonant frequencies of the transmitting coil.

10. The three-dimensional omnidirectional wireless power transfer system based on three frequencies according to any one of claims 1 to 9, characterized in that, The three transmitting coils can work individually or in any combination simultaneously; As the receiving coil moves with the load, the coupling coefficient between the receiving coil and the transmitting coil increases as the edges of the receiving coil and the transmitting coil get closer together.

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