Dome-shaped coupling mechanism and wireless charging system for UAVs and on-demand switching method

Abstract

This application provides a dome-shaped coupling mechanism and a wireless charging system for drones, along with an on-demand switching method, to address the problems of poor anti-offset capability and transmission stability in drone wireless charging systems. The coupling mechanism includes a three-dimensional transmitting coil array and a U-shaped receiving coil. The three-dimensional transmitting coil array includes a first transmitting coil of regular N-sided shape and N second transmitting coils arranged in a ring array outside the first transmitting coil. The second transmitting coils are regular M-sided coils, and their planes are set at an obtuse angle to the plane of the first transmitting coils. The first transmitting coil and the N first transmitting coils form a near-dome structure, wherein: and... This application relies on the magnetic coupling mechanism of the three-dimensional transmitting coil array and the U-shaped receiving coil, combined with a coarse coil positioning and PT-symmetric adaptive coil switching control method, to achieve efficient energy transfer under positional offset during drone charging.

Description

Technical Field

[0001] This invention relates to the field of wireless charging for drones, and in particular to a dome-shaped coupling mechanism, a wireless charging system for drones, and an on-demand switching method. Background Technology

[0002] With the increasingly widespread application of drones, efficient and convenient wireless power transfer technology has become crucial for continuously improving their endurance. The MC-WPT system uses coils as the core structure for power transfer, where the transmitting and receiving coils achieve energy transfer through electromagnetic field coupling. This transmission method has attracted widespread attention due to its high efficiency, convenience, and reliability. The MC-WPT system exhibits high transmission efficiency when the transmitting and receiving coils are directly aligned or only slightly offset; however, as the offset distance increases, the system's energy efficiency significantly degrades.

[0003] Currently, the design methods for offset-resistant wireless power transfer (WPT) systems are showing a diversified development trend. At the magnetic coupling mechanism design level, novel coil structures can be mainly classified into two categories: First, planar coil structures, such as DD-type, DDQ-type, and BP-type planar coils, have been widely used in the field of wireless charging for electric vehicles. However, these structures have high precision requirements, and their performance degrades significantly in application scenarios with large positional deviations, thus limiting their applicability. Second, multi-directional / omnidirectional three-dimensional coil structures, such as multi-dimensional orthogonal structures, polyhedral structures, and bowl-shaped structures, possess advantages such as uniform magnetic field spatial distribution and high transmission efficiency. However, their multi-coil time-division conduction control methods are complex, and their structural volume is large, making it difficult to meet the needs of lightweight applications such as wireless charging for drones. In terms of circuit topology and working mechanism, researchers mainly improve the system's anti-offset characteristics through the following approaches: First, a multi-transmitter coil timing control strategy, which uses control algorithms to achieve time-division conduction of multiple transmitter coils, constructing a directionally independent and controllable magnetic field distribution, thereby achieving precise energy transfer and optimizing energy efficiency while extending the offset tolerance. However, this relies on complex timing control algorithms for time-division drive, increasing the difficulty of system control. Second, a complex resonant network topology design, using compensation networks such as LCC and LCCL, and introducing additional inductor and capacitor elements to achieve constant current or constant voltage output characteristics, reducing the dependence on real-time control algorithms and simplifying control complexity. Third, a parity-time (PT) symmetric system design, which uses the critical coupling coefficient to define the effective transmission distance. When the actual coupling coefficient is greater than the critical value, the system transmission characteristics no longer fluctuate with changes in coupling state, exhibiting excellent parameter stability and achieving constant power and constant efficiency transmission.

[0004] A patent publication with announcement number CN118677127A discloses a wireless charging and positioning device and method for unmanned aerial vehicles (UAVs) based on a passive beacon array. This solution uses a multi-transmitter-to-single-receiver strategy as its core, combining passive beacon positioning technology to achieve group switching and intelligent opening and closing of a hexagonal polygonal transmitting coil planar array. The device integrates modules such as DC excitation, high-frequency inverter, compensation circuit, array transmitting coils, receiving coils, bidirectional rectifier-inverter, filtering, and load. A beacon detection module is placed at the center of each hexagonal transmitting coil in the planar array. The voltage sensing characteristics of the module complete the positioning of the receiving coil, and then the corresponding transmitting coil is switched based on the positioning result, thereby reducing ineffective energy loss and improving the energy transmission efficiency of the multi-transmitter-to-single-receiver wireless power transmission system. However, the coil design of this solution only revolves around a fixed planar array composed of seven hexagons. The adaptability to the positional offset of the receiving coil is limited to a preset range in the XY plane direction, and the coil occupies a large area, resulting in significant limitations in actual spatial adaptability.

[0005] In summary, existing research on wireless charging for drones faces the following key challenges: First, most anti-offset designs only consider two-dimensional planar motion, making it difficult to adapt to the free flight attitude changes of drones in three-dimensional space. Second, while traditional planar coils possess anti-offset performance, their space utilization is low, and while three-dimensional structures can achieve omnidirectional transmission, their complex design and high control costs limit their widespread application. Finally, the receiver positioning technology required for accurate power transmission is often complex and costly, providing positioning accuracy far exceeding the system's group control requirements, making it difficult to balance simplicity, reliability, and practicality. Summary of the Invention

[0006] The purpose of this invention is to provide a dome-shaped coupling mechanism, a wireless charging system for drones, and an on-demand switching method. This addresses the technical problems of poor anti-offset capability and transmission stability in drone wireless charging systems.

[0007] First, this application provides a dome-shaped coupling mechanism, including a transmitter and a receiver. The transmitter includes a three-dimensional transmitting coil array, and the receiver includes a U-shaped receiving coil.

[0008] The three-dimensional transmitting coil array includes a first transmitting coil of regular N-gon shape, and N second transmitting coils arranged in a ring array outside the first transmitting coil. The second transmitting coils are regular M-gon coils, and their planes are set at an obtuse angle to the plane of the first transmitting coil. The first transmitting coil and the N second transmitting coils form a near-dome structure, wherein: and .

[0009] Optionally, N can be 5 and M can be 6.

[0010] Secondly, this application provides a wireless charging system for unmanned aerial vehicles, including the aforementioned dome-shaped coupling mechanism. The transmitting end also includes a primary-side circuit, which includes a DC power supply, a high-frequency inverter, and N+1 switching compensation circuits.

[0011] The input terminals of the N+1 switching compensation circuits are all connected to the output terminals of the high-frequency inverter, and the output terminals of the N+1 switching compensation circuits are respectively connected to the first transmitting coil and the N second transmitting coils.

[0012] Optionally, each of the switching compensation circuits includes an anti-series MOSFET switch and a primary-side compensation capacitor;

[0013] One end of the anti-series MOSFET switch and the primary-side compensation capacitor is connected to one output terminal of the high-frequency inverter, the other end of the primary-side compensation capacitor is connected to one end of the transmitting coil, and the other end of the anti-series MOSFET switch and the transmitting coil is connected to the other output terminal of the high-frequency inverter. The anti-series MOSFET switch is used to control the transmitting coil to engage or disengage from the wireless charging system.

[0014] Optionally, the receiving end further includes a secondary circuit, which includes a secondary compensation capacitor and a load connected at one end to each other, and the other ends of the secondary compensation capacitor and the load are respectively connected to the two ends of the U-shaped receiving coil.

[0015] Optionally, it also includes a control circuit, which includes a current sampling module, a coil switching control module, a zero-crossing detection module, a dead zone generation module, and a drive circuit module;

[0016] The current sampling module is used to collect the inverter output current, the coil switching control module is used to control the anti-series MOSFET switch according to the inverter output current, the zero-crossing detection module is used to detect the zero crossing of the inverter output current, and the dead-time generation module is used to generate a PWM wave with a dead time according to the zero-crossing signal and send it to the drive circuit module to work, thereby forming a closed-loop control.

[0017] Finally, this application provides an on-demand switching method for a drone wireless charging system, used for switching control of the aforementioned drone wireless charging system, the specific steps of which are as follows:

[0018] S1: Obtain the circuit parameters of the wireless charging system and the desired power of wireless charging. ;

[0019] S2: Critical coupling coefficient of the computational system Initialize the number of currently active transmitting coils to 0;

[0020] S3: After the UAV docks, each transmitting coil is individually engaged in sequence, and the input voltage matched to the current transmitting coil is calculated; the transmitting end outputs according to the input voltage, and the primary current and operating frequency are collected; the system switches off all transmitting coils;

[0021] S4: Select the transmitting coil with the lowest operating current among the currently unused transmitting coils as the working coil, and update the total number of working coils. ;

[0022] S5: If Then proceed to step S7; if Proceed to step S6; if If the current location cannot meet the charging requirements, the gating process will stop, and the drone will try again after changing its location.

[0023] S6: Turn on the working coil selected in step S4, so that the number of working coils reaches [number missing]. 1, calculate the current The input voltage is matched to each transmitting coil, and the corresponding primary current and operating frequency are collected;

[0024] S7: Calculate the current actual coupling coefficient based on the collected data and circuit parameters. ,like If the control system completes charging, then charging will begin; if Return to step S4 to add the next optimal transmitting coil.

[0025] Optionally, the circuit parameters of the wireless charging system in step S1 include the self-inductance of the transmitting coil. Receiver coil self-inductance Parasitic resistance of transmitting coil Parasitic resistance of the receiving coil Load resistance Primary-side compensation capacitor and secondary side compensation capacitor ,in: .

[0026] Optionally, the input voltage matched to the transmitting coil is calculated as follows:

[0027] ;

[0028] in, This is the equivalent resistance of the receiving end. , The total resistance of the transmitting coil in the currently deployed system is [value missing]. This is the total self-inductance of the transmitting coil currently in the system.

[0029] Optionally, calculate the current actual coupling coefficient. for:

[0030] ;

[0031] in, The current primary-side current, This is the current input voltage of the transmitting coil. The current equivalent reactance of the transmitter. , The equivalent reactance of the receiving end. , This represents the current operating frequency of the system.

[0032] Because of the adoption of the above technical solution, the present invention has the following advantages:

[0033] 1. This application improves space utilization by constructing a three-dimensional transmitting and receiving coil, and introduces a PT symmetrical circuit mechanism to maintain stable power transmission efficiency during positional shifts, achieving three-dimensional spatial offset adaptation. Simultaneously, the time-division control strategy enhances transmission efficiency while integrating the coarse positioning function of the receiving coil, reducing the complexity of the control system.

[0034] 2. This application performs coarse positioning of the receiving coil and control of the transmitting coil's activation by comparing the coupling coefficients of the transmitting and receiving coils with the system's critical coupling coefficient. Compared with existing wireless power transfer systems, this application improves the system's positional robustness from both magnetic coupling mechanism and circuit mechanism aspects, possessing stronger engineering practicality and can be widely applied to wireless charging scenarios with a wide range and multiple degrees of freedom, such as drones.

[0035] 3. The transmitting coil of this application adopts a three-dimensional array layout, which makes more flexible use of space compared with planar coils. Through the coordinated arrangement of the center and the outer hexagons, the magnetic field coverage is uniform and the spatial coupling range is wide. The U-shaped receiving coil is designed according to the magnetic field contour lines. Compared with traditional circular coils, it can maintain a larger effective coupling area when offset, ensuring stable coupling strength under offset conditions. The three-dimensional transmitting coil and the U-shaped receiving coil form a precise energy transmission magnetic field with independent and controllable direction, uniform distribution, and high transmission efficiency, which can realize multi-degree-of-freedom power transmission.

[0036] 4. The PT-symmetric circuit construction mechanism of this application ensures that even if the transmitting and receiving coils are offset, the system transmission characteristics will not fluctuate with the change of coupling state when the actual coupling coefficient is greater than the critical coupling coefficient of the system, thereby improving the positional robustness of the wireless power transmission system.

[0037] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0038] The accompanying drawings of this invention are described below.

[0039] Figure 1 This is a schematic diagram of the magnetic coupling mechanism of the present invention.

[0040] Figure 2 This is a vector diagram showing the magnetic induction intensity when different transmitting coils are activated according to the present invention.

[0041] Figure 3 This is a magnetic induction intensity distribution diagram when different transmitting coils are turned on according to the present invention.

[0042] Figure 4 This is a circuit diagram of the wireless charging system for drones according to the present invention.

[0043] Figure 5 This is the equivalent circuit diagram of the wireless charging system for drones of the present invention.

[0044] Figure 6 This is a flowchart of the on-demand switching method for the drone wireless charging system of the present invention.

[0045] Figure 7 This is an unfolded view of the three-dimensional transmitting coil array of the present invention.

[0046] Figure 8 This is a spherical coordinate schematic diagram of the three-dimensional transmitting coil array of the present invention.

[0047] Figure 9 This is a comparison diagram of the traditional receiving coil and the U-shaped receiving coil under three different models of the present invention.

[0048] Figure 10 This is a graph showing the change in system energy efficiency as a function of the radial distance of the U-shaped receiving coil.

[0049] Figure 11 This is a graph showing the change in system energy efficiency as a function of the U-shaped receiving coil position and polar angle.

[0050] Figure 12 This is a graph showing the change in system energy efficiency as a function of the azimuth angle of the U-shaped receiving coil.

[0051] In the diagram: 1 is the first transmitting coil; 2-6 are the second transmitting coils; 7 is the U-shaped receiving coil. Detailed Implementation

[0052] The present invention will be further described below with reference to the accompanying drawings and embodiments. The terms "inner," "outer," etc., indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the embodiments of the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified and limited, the terms "connected" and "linked" should be interpreted broadly, for example, as a fixed connection, a detachable connection, an integral connection, an electrical connection, or a signal connection; it can be a direct connection or an indirect connection through an intermediate medium.

[0053] Example 1:

[0054] like Figure 1 The dome-shaped coupling mechanism shown includes a transmitter and a receiver. The transmitter includes a three-dimensional transmitting coil array, and the receiver includes a U-shaped receiving coil.

[0055] The three-dimensional transmitting coil array includes a first transmitting coil of regular N-gon shape, and N second transmitting coils arranged in a ring array outside the first transmitting coil. The second transmitting coils are regular M-gon coils, and their planes are set at an obtuse angle to the plane of the first transmitting coil. The first transmitting coil and the N second transmitting coils form a near-dome structure, wherein: and .

[0056] In this embodiment, N is 5, M is 6, and the U-shaped receiving coil, the first transmitting coil, and the N second transmitting coils all have 16 turns. The first transmitting coil is a regular pentagonal planar coil with a side length of 50mm; the five second transmitting coils are regular hexagonal planar coils with a side length of 50mm, and are folded downwards at 52° so that the planes fit tightly together to form a near-dome structure.

[0057] The U-shaped receiving coil has a symmetrical "U"-shaped frame structure, formed by folding the left and right sides of a rectangular coil upwards at 90° to create a three-dimensional frame structure with a length of 90mm, a width of 90mm, and a height of 50mm. Its overall dimensions match those of the transmitting coil. Designed based on magnetic field contour lines, the U-shaped receiving coil, compared to traditional circular coils, maintains a larger effective coupling area during offset, ensuring stable coupling strength under offset conditions.

[0058] Figure 1 In the diagram: 1 is the first transmitting coil, 2-6 are five second transmitting coils respectively, and 7 is a U-shaped receiving coil. Analysis of the coupling system follows:

[0059] like Figure 2 (a) and Figure 3 As shown in (a), when only the first transmitting coil 1 is activated, the primary side self-inductance is minimized, resulting in low system input power loss. If the U-shaped receiving coil 7 is precisely aligned, the transmission efficiency of a single coil is high. This adapts to the ideal charging condition where the U-shaped receiving coil 7 is perfectly aligned without offset, making it one of the optimal charging modes for precise drone alignment.

[0060] like Figure 2 (b) and Figure 3 As shown in (b), when only the second transmitting coil 2 is activated, although its primary-side self-inductance and parasitic resistance are slightly greater than those of the first transmitting coil 1, the mutual inductance coefficient is higher due to the high matching between the side-folded structure of the U-shaped receiving coil 7 and the magnetic induction intensity vector line of the transmitting coil. This results in high transmission power and efficiency. This configuration is suitable for the charging condition where the U-shaped receiving coil 7 is directly opposite the surrounding hexagonal coil, and is also one of the optimal communication modes for precise drone positioning.

[0061] like Figure 2 (c) and Figure 3 As shown in (c), when the first transmitting coil 1 and the second transmitting coil 2 are turned on, the total reactance of the circuit increases slightly compared to a single coil. However, due to the increase in mutual inductance M caused by the superposition of magnetic fields, the coupling strength is improved, and the overall transmission efficiency of the system remains high, balancing efficiency and positional robustness. This optimal balance mode between efficiency and fault tolerance is a practically valuable selection method for UAV charging, suitable for slight offset conditions.

[0062] like Figure 2 (d) and Figure 3 As shown in (d), when the second transmitting coil 2 and the second transmitting coil 3 are turned on, and the U-shaped receiving coil 7 is located on the vertical line of the two surrounding coils, the mutual inductance coupling is complex and the transmission efficiency is lower than that of the center participation mode. It is mainly aimed at the extreme offset problem of the UAV landing on the edge of the outer coil and is an important supplement to the array robustness.

[0063] like Figure 2 (e) and Figure 3 As shown in (e), when the first transmitting coil 1, the second transmitting coil 2, and the second transmitting coil 3 are turned on, the coupling coefficient is... While achieving the highest stability, the total circuit reactance and parasitic losses increase compared to single / dual coils, resulting in a decrease in overall system transmission efficiency. This configuration has the highest energy consumption and is only suitable for extreme conditions involving significant UAV positional shifts, representing the system's maximum preset selection number. With more than three coils, losses become extremely high, transmission efficiency drops drastically, and the system loses its practical engineering value.

[0064] In summary, the dome-shaped coupling mechanism of this application employs a three-dimensional array layout for the transmitting coil array, which offers greater space utilization compared to planar coils. Furthermore, the coordinated arrangement of the central and peripheral hexagons ensures uniform magnetic field coverage and a wide spatial coupling range, overcoming the directional limitations of planar coil arrays. The U-shaped receiving coil, designed based on magnetic field contour lines, maintains a larger effective coupling area during offset compared to traditional circular coils, ensuring stable coupling strength under offset conditions. Compared to traditional magnetic coupling structures, it exhibits significant advantages in magnetic field distribution, positional robustness, coupling efficiency, and engineering practicality.

[0065] Example 2:

[0066] like Figure 4 The drone wireless charging system shown includes the dome-shaped coupling mechanism described in Embodiment 1, and also includes a primary side circuit, a secondary side circuit, and a control circuit.

[0067] The primary circuit includes a DC power supply. The system includes a high-frequency inverter and N+1 switching compensation circuits. The input terminals of the N+1 switching compensation circuits are all connected to the output terminals of the high-frequency inverter, and the output terminals of the N+1 switching compensation circuits are respectively connected to the first transmitting coil and N second transmitting coils.

[0068] The switching compensation circuits all include anti-series MOSFET switches and primary-side compensation capacitors. (in: The anti-series MOSFET switch and primary-side compensation capacitor); One end of the primary-side compensation capacitor is connected to one output terminal of the high-frequency inverter. The other end is connected to the transmitting coil One end is connected to the anti-series MOSFET switch and the emitter coil. The other end is connected to the other output terminal of the high-frequency inverter, and the anti-series MOSFET switch is used to control the transmitting coil. To engage or disengage the wireless charging system.

[0069] In this embodiment, the high-frequency inverter is a full-bridge inverter, including... Four MOSFETs, DC power supply Together with a high-frequency inverter, they form an inverter power supply; the transmitting coil It includes a first transmitting coil 1 and five second transmitting coils (2~6); the anti-series MOSFET switch includes two MOSFETs connected in reverse series. and transmitting coil Together with the switching compensation circuit, it forms the transmitting coil circuit.

[0070] The secondary circuit includes secondary compensation capacitors connected at one end to each other. and load The secondary-side compensation capacitor and load The other end is connected to both ends of the U-shaped receiving coil 7, and the secondary circuit and the U-shaped receiving coil 7 constitute the receiving coil circuit.

[0071] The control circuit includes a current sampling module, a coil switching control module, a zero-crossing detection module, a dead-time generation module, and a drive circuit module. The current sampling module is used to collect the inverter output current. The coil switching control module is used to control the anti-series MOSFET switch according to the inverter output current. The zero-crossing detection module is used to detect the zero-crossing of the inverter output current. The dead-time generation module is used to generate a PWM wave with a dead time according to the zero-crossing signal and send it to the drive circuit module to work, thereby forming a closed-loop control.

[0072] In this embodiment, the control circuit's control of the high-frequency inverter is prior art and will not be described in detail here. During actual circuit operation, regardless of the number of transmitting coils connected, they will always be in series; therefore, it can be viewed as an SS topology circuit structure with a single transmitting coil to a single receiving coil. The system equivalent circuit diagram is as follows: Figure 5 As shown.

[0073] Figure 5 middle, The inverter input voltage for the transmitting coil. and These are the self-inductances of the transmitting coil and the receiving coil, respectively. and These are the primary and secondary currents, respectively. and These are the parasitic resistances of the transmitting coil and the receiving coil, respectively. For load resistance, and These are the primary transformer and secondary side compensation capacitors, respectively. Let the transmitting and receiving coils be mutually inductant. Let the equivalent resistance at the receiving end be... Transmitter equivalent reactance Receiver equivalent reactance The corresponding KVL equation is:

[0074] (1)

[0075] Given the primary current and input voltage of the system, substituting the coupling coefficient and mutual inductance relationship into equation (1), the coupling coefficient of the system at different locations can be obtained as follows:

[0076] (2)

[0077] According to the above formula, it can be seen that when the input voltage remains constant, the primary current is negatively correlated with the coupling coefficient, that is, the smaller the primary current, the higher the coupling degree between the current transmitting coil and the receiving coil.

[0078] The natural oscillation frequencies of the primary and secondary sides of the system are both We can obtain:

[0079] (3)

[0080] Solving equation (3) yields the parameter criteria for the compensation capacitor:

[0081] (4)

[0082] set up Given the resistance of the power supply element, the total resistance at the transmitting end is... for Substituting the above equation into equation (1) and separating the real and imaginary parts, we get:

[0083] (5)

[0084] When the system satisfies the PT symmetry condition and ensures that the system angular frequency is a real solution, the critical coupling coefficient that needs to be satisfied is:

[0085] (6)

[0086] At this time, the transmission efficiency and power of the system are shown in Equation (7). It can be seen that when the system is working in PT state, the efficiency and power are not related to the mutual inductance, that is, the power efficiency is basically unaffected by the position offset.

[0087] (7)

[0088] Based on the derivation of the circuit model above, the following conclusions can be drawn: 1. As the number of transmitting coils connected increases, the total self-inductance and total parasitic resistance of the primary coil increase, resulting in a decrease in the secondary load power; 2. Under the condition of constant input voltage, the smaller the current value of the transmitting coil, the higher the coupling degree between the transmitting coil and the receiving coil at the current position. In order to reduce the number of transmitting coils connected, the control strategy prioritizes the selection of transmitting coils with small current values ​​when connected alone.

[0089] Example 3:

[0090] like Figure 6 The method for on-demand switching of a drone wireless charging system, as shown in Embodiment 2, is used to control the drone wireless charging system. The specific steps are as follows:

[0091] S1: Obtain the circuit parameters of the wireless charging system and the desired power of wireless charging. ;

[0092] In this embodiment, the circuit parameters of the wireless charging system include the self-inductance of the transmitting coil. Receiver coil self-inductance Parasitic resistance of transmitting coil Parasitic resistance of the receiving coil Load resistance Primary-side compensation capacitor and secondary side compensation capacitor ,in: .

[0093] S2: Critical coupling coefficient of the computational system Initialize the number of currently active transmitting coils to 0;

[0094] In this embodiment, the critical coupling coefficient of the system is calculated using equation (6). Define the states of the 6 transmitting coils as "state[j]=0 or 1". When "state[j]=0", it means that the j-th transmitting coil is cut off from the system, and when "state[j]=1", it means that the j-th transmitting coil is put into the system.

[0095] S3: After the UAV docks, each transmitting coil is individually engaged in sequence, and the input voltage matched to the current transmitting coil is calculated; the transmitting end outputs according to the input voltage, and the primary current and operating frequency are collected; the system switches off all transmitting coils ("state[j]=0").

[0096] (8)

[0097] in, This is the equivalent resistance of the receiving end. , The total resistance of the transmitting coil in the currently deployed system is [value missing]. This is the total self-inductance of the transmitting coil currently in the system.

[0098] S4: Select the transmitting coil with the lowest operating current among the currently unconnected transmitting coils. As a working coil, the state of the transmitting coil is updated to "state [ "]=1" updates the total number of currently active coils. ;

[0099] S5: If Then proceed to step S7; if Proceed to step S6; if If the current location cannot meet the charging requirements, the gating process will stop, and the drone will try again after changing its location.

[0100] S6: Connect the working coil selected in step S4 This makes the number of working coils reach One, by calculating the current The input voltage is matched to each transmitting coil, and the corresponding primary current and operating frequency are collected;

[0101] S7: Calculate the current actual coupling coefficient based on the collected data and circuit parameters. ,like If the control system completes charging, it will start charging and output the current coil connection status; if Return to step S4 to add the next optimal transmitting coil.

[0102] In this embodiment, the current actual coupling coefficient is calculated using equation (2). ,in, The current primary-side current, This is the current input voltage of the transmitting coil. The current equivalent reactance of the transmitter. , The equivalent reactance of the receiving end. , This represents the current operating frequency of the system.

[0103] S8: Analysis and Experiment:

[0104] S8.1: Spatial attitude modeling based on spherical coordinates:

[0105] Based on previous analysis, this study aims to study and analyze the arbitrary posture of wireless power transmission systems in three-dimensional space, such as... Figure 7 and Figure 8 As shown, this application adopts a spherical coordinate system structure design, from radial distance Polar angle and azimuth A systematic analysis of the coil's energy efficiency characteristics is conducted across three dimensions. This structure enables spatial offset of the receiving coil in the X, Y, and Z directions, thereby simulating the spatial attitude changes of a UAV in practical applications and creating a test environment that more closely resembles real-world engineering applications for system performance evaluation. The structure of the spherical coordinate system is as follows: Figure 8 As shown, the origin position, radial distance and offset polar angle and other related parameters are obtained by equation (10).

[0106] (10)

[0107] S8.2: Comparison and Performance Analysis of Receiver Coil Structures:

[0108] To achieve transmission stability and adaptability of the wireless power transmission system under three-dimensional spatial attitude changes, this application is based on the PT working mechanism, through coupling coefficients... With critical coupling coefficient Evaluation of the U-shaped receiving coil of this application ( Figure 9 The performance difference between the novel coil and the traditional circular receiving coil is shown in the experimental results. Figure 9 As shown.

[0109] Figure 9 (a), (b), and (c) show the experimental results of the system switching sequentially to three operating modes: first transmitting coil 1, first transmitting coil 1 and second transmitting coil 2, and second transmitting coil 2, respectively. The experimental results show that as the angular offset increases, in these three cases, the coupling coefficient of the traditional circular coil decreases when the angular offset is small. Rapidly dropped to the critical coupling coefficient The system then enters the PT breakage zone; however, the U-shaped receiving coil of this application operates within a wider angular offset range. The value is always higher than This ensures that the system continues to operate in a high-efficiency transmission state. This result demonstrates that the U-shaped receiving coil of this application significantly improves the robustness of the PT symmetrical wireless charging system to angular shifts.

[0110] S8.3: Simulation Verification of Wireless Power Transfer System:

[0111] In the simulation model, the coil structure and positioning strategy described in step S8.2 above are adopted. The first and second transmitting coils, as well as the U-shaped receiving coil, are all set to 16 turns, with the desired power set to 20W. The U-shaped receiving coil is set to a passive state (no current or voltage excitation is applied). Considering that this application involves three-dimensional variables and the number of simulation case combinations is too large to verify individually, this application analyzes the radial distance of the U-shaped receiving coil under typical conditions. Polar angle and azimuth The offsets in three directions and their corresponding energy efficiency characteristics were simulated using multiple sets of coil offsets.

[0112] like Figure 10 As shown, this application conducts radial distance offset tests in two typical regions of the transmitting end (the center of the first transmitting coil 1 and the center of the second transmitting coil 2) to analyze the radial distance offset of the U-shaped receiving coil. The directional shift and the corresponding changes in load power and transmission efficiency.

[0113] Experimental results show that: Within the PT symmetry region, the first transmitting coil 1 is transmitted. Figure 10 (middle connecting coil 1) and second transmitting coil 2) Figure 10 Both the intermediate switching coil 2) exhibited excellent stability, with power outputs around 20W, and both maintained a relatively high transmission efficiency of 70%. After the PT breakage zone, the system's energy efficiency characteristics show significant differentiation. The load power increases dramatically with increasing radial distance, while the transmission efficiency continuously decreases. Among them, the efficiency of the second transmitting coil 2 decreases at a slower rate and still maintains a relative advantage under large offsets. This verifies the performance advantage of this transmitting coil in different application scenarios.

[0114] To verify the robustness of the localization strategy and PT symmetry, Figure 11 For a U-shaped receiving coil with a radial offset of 4 cm, the system load power and transmission efficiency vary with the polar angle of the receiving coil. Changes in offset. For example... Figure 11 As shown, within the deflection range of 0° to 10°, the system operates in conjunction with the first transmitting coil 1; when the angle increases to 20°, the system switches to the combined operating mode of the first transmitting coil 1 and the second transmitting coil 2; within a wide angle range of 30° to 50°, the system switches to the second transmitting coil 2. Within these deflection ranges, the system remains in the PT symmetry region, with the load power consistently between 19.46W and 20.04W, and the efficiency consistently between 69.45% and 70.82%, exhibiting excellent attitude robustness. When the angle reaches 60°, the system enters the PT symmetry fragmentation region and has departed from the stable transmission state. In summary, under a radial deflection of 4 cm, this system possesses efficient and stable power transmission capabilities within the deflection range of 0° to 50°.

[0115] Because the transmitting coil structure is symmetrical, the energy efficiency characteristics of the verification system vary with the azimuth angle of the U-shaped receiving coil. When considering the variation law of offset, only the spherical coordinate system needs to be considered. The range of 0° to 36° is acceptable. Figure 12 Typical working conditions Below, the azimuth angle of the U-shaped receiving coil The curves showing the change in load power versus transmission efficiency under varying load conditions. Experimental results show that as the load power changes... As the system increases, it gradually approaches the PT-symmetric region. At this point, the system enters the PT symmetric state, with the load power stabilizing at around 20W and the efficiency stabilizing at around 70%. This clearly demonstrates that the transmitting coil can achieve efficient and stable energy transmission over a relatively large range.

[0116] In summary, this application combines a PT-symmetric circuit mechanism with a precise energy transfer magnetic coupling mechanism. The PT-symmetric mechanism solves the problem of sensitivity to coupling state in traditional systems, maintaining stable transmission characteristics and significantly improving position robustness and transmission stability. The three-dimensional dome-shaped transmitting coil improves the magnetic field distribution, enabling multi-degree-of-freedom energy transfer and overcoming the directional limitations of planar coil arrays. The time-division control strategy improves transmission efficiency while integrating the coarse positioning function of the receiving coil. Through adaptive gating of the coil, it reduces control complexity and additional positioning hardware, achieving a dual optimization of efficient energy transfer and system simplification.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A dome-shaped coupling mechanism, comprising a transmitter and a receiver, characterized in that, The transmitting end includes a three-dimensional transmitting coil array, and the receiving end includes a U-shaped receiving coil; The three-dimensional transmitting coil array includes a first transmitting coil of regular N-gon shape, and N second transmitting coils arranged in a ring array outside the first transmitting coil. The second transmitting coils are regular M-gon coils, and their planes are set at an obtuse angle to the plane of the first transmitting coil. The first transmitting coil and the N second transmitting coils form a near-dome structure, wherein: and .

2. The dome-shaped coupling mechanism according to claim 1, characterized in that, The value of N is 5, and the value of M is 6.

3. A wireless charging system for unmanned aerial vehicles, characterized in that, The transmitter includes the dome-shaped coupling mechanism as described in claim 1 or 2, and the primary side circuit includes a DC power supply, a high-frequency inverter, and N+1 switching compensation circuits. The input terminals of the N+1 switching compensation circuits are all connected to the output terminals of the high-frequency inverter, and the output terminals of the N+1 switching compensation circuits are respectively connected to the first transmitting coil and the N second transmitting coils.

4. The wireless charging system for unmanned aerial vehicles according to claim 3, characterized in that, The switching compensation circuits all include anti-series MOSFET switches and primary-side compensation capacitors; One end of the anti-series MOSFET switch and the primary-side compensation capacitor is connected to one output terminal of the high-frequency inverter, the other end of the primary-side compensation capacitor is connected to one end of the transmitting coil, and the other end of the anti-series MOSFET switch and the transmitting coil is connected to the other output terminal of the high-frequency inverter. The anti-series MOSFET switch is used to control the transmitting coil to engage or disengage from the wireless charging system.

5. A wireless charging system for unmanned aerial vehicles according to claim 3, characterized in that, The receiving end also includes a secondary circuit, which includes a secondary compensation capacitor and a load connected at one end to each other, and the other ends of the secondary compensation capacitor and the load are respectively connected to the two ends of the U-shaped receiving coil.

6. A wireless charging system for unmanned aerial vehicles according to claim 4, characterized in that, It also includes a control circuit, which includes a current sampling module, a coil switching control module, a zero-crossing detection module, a dead-zone generation module, and a drive circuit module; The current sampling module is used to collect the inverter output current, the coil switching control module is used to control the anti-series MOSFET switch according to the inverter output current, the zero-crossing detection module is used to detect the zero crossing of the inverter output current, and the dead-time generation module is used to generate a PWM wave with a dead time according to the zero-crossing signal and send it to the drive circuit module to work, thereby forming a closed-loop control.

7. A method for on-demand switching of a wireless charging system for unmanned aerial vehicles, characterized in that, The wireless charging system for drones according to any one of claims 3-6, used for control of switching, comprises the following steps: S1: Obtain the circuit parameters of the wireless charging system and the desired power of wireless charging. ; S2: Critical coupling coefficient of the computational system Initialize the number of currently active transmitting coils to 0; S3: After the UAV docks, each transmitting coil is individually engaged in sequence, and the input voltage matched to the current transmitting coil is calculated; the transmitting end outputs according to the input voltage, and the primary current and operating frequency are collected; the system switches off all transmitting coils; S4: Select the transmitting coil with the lowest operating current among the currently unused transmitting coils as the working coil, and update the total number of working coils. ; S5: If Then proceed to step S7; if Proceed to step S6; if If the current location cannot meet the charging requirements, the gating process will stop, and the drone will try again after changing its location. S6: Turn on the working coil selected in step S4, so that the number of working coils reaches [number missing]. 1, calculate the current The input voltage is matched to each transmitting coil, and the corresponding primary current and operating frequency are collected; S7: Calculate the current actual coupling coefficient based on the collected data and circuit parameters. ,like If the control system completes charging, then charging will begin; if Return to step S4 to add the next optimal transmitting coil.

8. The on-demand switching method for a drone wireless charging system according to claim 7, characterized in that, The circuit parameters of the wireless charging system in step S1 include the self-inductance of the transmitting coil. Receiver coil self-inductance Parasitic resistance of transmitting coil Parasitic resistance of the receiving coil Load resistance Primary-side compensation capacitor and secondary side compensation capacitor ,in: .

9. The on-demand switching method for a drone wireless charging system according to claim 8, characterized in that, The input voltage for matching the transmitting coil is calculated as follows: ； in, This is the equivalent resistance of the receiving end. , The total resistance of the transmitting coil in the currently deployed system is [value missing]. This is the total self-inductance of the transmitting coil currently in the system.

10. The on-demand switching method for a drone wireless charging system according to claim 9, characterized in that, Calculate the current actual coupling coefficient for: ； in, The current primary-side current, This is the current input voltage of the transmitting coil. The current equivalent reactance of the transmitter. , The equivalent reactance of the receiving end. , This represents the current operating frequency of the system.

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