An on-board wireless charging device and a charging method of an overhead line inspection unmanned aerial vehicle

Abstract

The application relates to the technical field of wireless charging, in particular to an airborne wireless charging device and a charging method for an overhead line inspection unmanned aerial vehicle, which comprises a battery state monitoring module, a data analysis module, a control module, a data exchange module, a communication module, a receiving coil, a compensation module, a rectifier, a step-down converter, a protection module and an external interface. The data analysis module is used for data analysis on the received battery state parameter data and the charging unit. The control module is internally provided with a PID controller, which is used for adaptive setting of parameters in the PID controller according to real-time data analysis indexes of the data analysis module, dynamic adjustment of a phase-shifting angle of an inverter based on a control signal generated by the PID, and adjustment of charging power of each charging unit when charging the airborne battery of the unmanned aerial vehicle. The application aims to realize dynamic adjustment of charging power in a closed-loop charging process from a constant-current charging stage to a constant-voltage charging stage mode.

Description

Technical Field

[0001] This application relates to the field of wireless charging technology, specifically to an airborne wireless charging device and charging method for an overhead power line inspection drone. Background Technology

[0002] Line inspection is an important means to ensure the normal operation of overhead lines. In order to control the flexibility of drone inspection, the current inspection is mainly carried out by small multi-rotor models, with a flight time of 30 to 60 minutes. Overhead line inspection is usually carried out over a large area and long distance, which requires frequent battery replacement, seriously affecting the inspection efficiency.

[0003] To address the issue of short battery life, the mainstream approach is to deploy fixed or mobile drone nests along the route and reduce range anxiety through wireless charging management. Mobile drone nests have been piloted in many parts of the country: they can plan routes in advance, and after completing inspections along the trajectory, the drones autonomously return to the nest, receiving energy using the electromagnetic coupling coil inside the nest, recharging without the need for cables, and then continuing their mission.

[0004] However, during multi-aircraft collaborative inspections, the remaining power and battery temperature of each aircraft vary greatly. If only a general restriction is placed on "the total power of the wireless charging system during charging does not exceed the threshold", the nesting end cannot adjust the coil coupling gap and power transmission curve in real time. Furthermore, the transmission efficiency of the wireless charging system is prone to drop and heats up during charging, making it difficult for some aircraft to be fully charged and resume flight on time. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides an airborne wireless charging device and charging method for an overhead power line inspection drone. The specific technical solution adopted is as follows:

[0006] In a first aspect, embodiments of this application provide an airborne wireless charging device for an overhead power line inspection drone, the device comprising:

[0007] The battery status monitoring module is used to collect real-time status parameter data of the drone's onboard battery;

[0008] Data analysis module; used to analyze the received battery status parameter data and charging unit data;

[0009] The control module has a built-in PID controller, which is used to adaptively adjust the parameters in the PID controller based on the real-time data analysis indicators of the data analysis module. Based on the control signal generated by the PID, the inverter phase shift angle is dynamically adjusted to adjust the charging power of each charging unit when charging the drone's onboard battery.

[0010] The data exchange module is used to synchronize the monitoring data of this device with the monitoring data of the mobile charging unit on the cell side to the control module;

[0011] The communication module is used for bidirectional transmission of control commands and status parameter data with the mobile housing;

[0012] The receiving coil, loosely coupled to the transmitting coil of the cell, is used to convert the high-frequency magnetic field into alternating current.

[0013] The compensation module adopts a series-parallel hybrid topology for reactive power compensation and to improve the power factor.

[0014] A rectifier is used to convert AC power, after compensation by a compensation module, into DC power.

[0015] A buck converter is used to regulate and adjust the voltage of the rectified output to meet battery charging specifications.

[0016] The protection module is used to actively disconnect the charging circuit when the temperature exceeds the limit, the duration exceeds the limit, or abnormal parameters occur.

[0017] External interface for exporting inspection data, firmware upgrades, and function expansion.

[0018] Secondly, this application also provides an airborne wireless charging method for an overhead power line inspection drone. This method is used to implement the adaptive adjustment of parameters in the PID controller within the data analysis module and control module of the aforementioned airborne wireless charging device. The method includes:

[0019] By analyzing the difference between the initial charging power of the drone to be charged and the preset charging value, the DC power of the power source in the mobile drone housing is used to allocate DC power to the charging unit of the drone to be charged, so as to obtain the transmission efficiency during the charging process of the drone's onboard battery.

[0020] By utilizing the deviation angle between the attitude angle of the drone during charging and the optimal attitude angle, as well as the alignment and coupling of the transmitting coil of the charging unit and the receiving coil on the drone's onboard wireless charging device, the first constraint index A during drone onboard battery charging is determined.

[0021] The second constraint index B during drone onboard battery charging is determined by using the number of charging units involved in battery charging and the battery health at the initial moment of drone charging.

[0022] The adjustment step size at each charging moment is set by using the average of the first and second constraint indices. Combined with the trend characteristics of the transmission efficiency change during the charging process of the UAV's onboard battery, the parameter adjustment rules in the PID controller at each charging moment are constructed. The difference between the transmission efficiency and the rated transmission efficiency at each charging moment is used as input, and the control signal is dynamically generated by the PID controller.

[0023] Preferably, the method for allocating DC power to each charging unit participating in battery charging is as follows:

[0024] Calculate the proportion of the difference in power between the initial charging power of the drone to be charged and the preset charging value to the total power difference of all drones to be charged.

[0025] The product of the ratio and the DC power of the power source in the mobile nest is used as the DC power allocated to the charging unit for the drone to be charged.

[0026] Preferably, the preset charging amount is used as a power indicator during mode switching between the constant current charging stage and the constant voltage charging stage, and is obtained through a preset ratio of the target charging amount.

[0027] Preferably, the expression for the first constraint index A is:

[0028]

[0029] In the formula, This indicates the drone's attitude angle at the initial moment of charging. Indicates the optimal attitude angle; This represents the coupling coefficient corresponding to the vertical distance between the transmitting coil and the receiving coil at the initial moment of charging. This represents the theoretical maximum value of the coupling coefficient.

[0030] Preferably, the method for determining the coupling coefficient corresponding to the vertical distance between the transmitting coil and the receiving coil at the initial charging moment is as follows:

[0031] The vertical distance between the transmitting and receiving coils during the drone's hovering process is collected and curve fitting is performed.

[0032] Obtain the coupling coefficient corresponding to the vertical distance between the transmitting coil and the receiving coil at the initial charging moment on the fitted curve.

[0033] Preferably, the expression for the second constraint index is:

[0034]

[0035] In the formula, This represents an exponential function with the natural constant as the base, where N represents the number of charging units involved in battery charging. This indicates the maximum battery health level. The battery health of the drone at the initial moment of charging.

[0036] Preferably, the step of constructing parameter adjustment rules in the PID controller for each charging moment, based on the trend characteristics of transmission efficiency changes during the charging process of the UAV's onboard battery, includes:

[0037] A linear fit is performed on the transmission efficiency at the current charging moment and the M preset historical charging moments before it;

[0038] When the slope of the fitted line is less than 1, the integral term is adjusted;

[0039] When the slope of the fitted line is greater than 1, the proportional and differential terms are adjusted sequentially.

[0040] When the slope of the fitted line is equal to 1, no adjustment is made.

[0041] Preferably, the setting expression for the adjustment step size at each charging moment is:

[0042]

[0043] In the formula, This represents the adjustment step size at time t during the charging process of the a-th charging unit. t represents the start time of the charging of the drone's onboard battery by the a-th charging unit, and t represents the current time. It is the normalized value of the sum of the first constraint index and the second constraint index when the a-th charging unit charges the onboard battery of the drone.

[0044] Preferably, the proportional, integral, and differential terms adjusted at time t during the charging process of the a-th charging unit for the UAV's onboard battery are respectively expressed as: , , :

[0045]

[0046]

[0047]

[0048] In the formula, This represents the slope of the fitted straight line at time t during the charging process of the a-th charging unit; , , Let represent the proportional term, integral term, and differential term at time t-1 during the charging process of the a-th charging unit, respectively.

[0049] This application has at least the following beneficial effects:

[0050] This application first determines the preset values ​​for charging each onboard battery based on the UAV's inspection in the previous and next phases, and sets up a redundancy mechanism to ensure the completion of subsequent inspection tasks. Secondly, it adaptively allocates DC power based on the required power of the battery connected to each charging unit. Then, it sets first and second constraint indicators using onboard wireless charging device and battery monitoring data, and adaptively adjusts the parameters of the PID controller based on the stability of transmission efficiency at continuous intervals for each charging unit. This generates the inverter's target heading angle. By using the current heading angle and the target heading angle, a PWM drive signal is generated to dynamically adjust the DC voltage and current at the transmitter, achieving dynamic adjustment of charging power. The charging power adjustment is performed on the mobile UAV side. Combined with the protection module of the onboard wireless charging device, the safety of wireless charging is sufficiently high, achieving a closed-loop charging mode of constant current charging stage – constant voltage charging stage. Attached Figure Description

[0051] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0052] Figure 1 This is a flowchart illustrating the steps of an airborne wireless charging method for an overhead power line inspection drone according to this application. Detailed Implementation

[0053] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of an airborne wireless charging device and charging method for an overhead power line inspection drone proposed in this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0055] The following description, in conjunction with the accompanying drawings, details the specific scheme of the airborne wireless charging device and charging method for an overhead power line inspection drone provided in this application.

[0056] One embodiment of this application provides an airborne wireless charging device for an overhead power line inspection drone, which includes a battery status monitoring module, a data analysis module, a control module, a data exchange module, a communication module, a receiving coil, a compensation module, a rectifier, a step-down converter, a protection module, and an external interface.

[0057] Among them, the battery status monitoring module is used to collect the status parameter data of the drone's onboard battery in real time;

[0058] Data analysis module; used to analyze the received battery status parameter data and charging unit data;

[0059] The control module has a built-in PID controller, which is used to adaptively tune the parameters in the PID controller based on the real-time data analysis indicators of the data analysis module. Based on the control signal generated by the PID, the inverter phase shift angle is dynamically adjusted to adjust the charging power of each charging unit when charging the drone's onboard battery.

[0060] The data exchange module is used to synchronize the monitoring data of this device with the monitoring data of the charging unit on the cell side to the control module;

[0061] The communication module is used for bidirectional transmission of control commands and status parameter data with the mobile nest. It can adopt Bluetooth Low Energy (BLE) or Narrowband Internet of Things (NB-IoT) technology to reduce energy consumption while meeting communication requirements.

[0062] The receiving coil is used to magnetically couple and charge the wireless charging coil on the mobile device, thereby converting magnetic field energy into electrical energy.

[0063] Compensation modules are used for reactive power compensation to improve the power factor. This is because the loose coupling between coils during magnetic induction coupling results in high leakage inductance and low coupling rate, leading to a relatively large proportion of reactive power in the circuit. There are two main types of compensation modules: series compensation and parallel compensation.

[0064] A rectifier is used to convert AC power, after compensation by a compensation module, into DC power.

[0065] A step-down converter is used to stabilize and regulate the DC output of the rectifier to ensure that the output voltage meets the battery charging standards.

[0066] The protection module is used to disconnect the charging connection with the mobile battery cell to protect the safety of the equipment. When abnormal parameters are detected, it will actively disconnect the connection with the mobile battery cell, such as the battery temperature exceeding the rated temperature range for 30 seconds or the charging time exceeding the maximum charging time.

[0067] External modules are used for exporting inspection data and updating firmware, as well as connecting external devices (such as servos and sensors) to expand the drone's functionality according to the inspection task requirements.

[0068] Another embodiment of this application provides an airborne wireless charging method for an overhead power line inspection drone, the steps of which are shown in the attached flowchart. Figure 1 As shown, this method is used to implement the adaptive adjustment of parameters in the PID controller of the data analysis module and control module in the airborne wireless charging device. The specific steps of this method are as follows:

[0069] Step 1: Based on the inspection requirements of overhead lines, pre-set inspection tasks for several drones and obtain the status parameter data of the onboard battery of each drone in real time during the inspection process.

[0070] The typical working method of a mobile drone nest is to pre-set the inspection tasks of each drone and generate flight paths for each time period according to the inspection needs of overhead lines. The drones take off automatically, complete the inspection work according to the predetermined route, and then return automatically to the nest for charging or manual battery replacement.

[0071] In this application, the duration of each time period is set to 30-60 minutes, and the number of drones inspected in each time period is denoted as M. Before the drones take off automatically, the operator or other personnel will import the flight trajectory generated by the inspection task of each drone into each drone. After the drones take off, they will perform the inspection task according to the received flight trajectory and return automatically.

[0072] For any given drone, during each drone's inspection process, the drone's location information is obtained in real time through the drone's onboard positioning module. This information is then used in conjunction with the drone's ultrasonic obstacle avoidance system to guide the drone to automatically land at a designated charging location in the mobile drone nest upon return. Each charging location has a charging unit that, in conjunction with the onboard wireless charging device, charges the battery.

[0073] Step 2: Based on the remaining power of each drone during charging, the power required for the next inspection task, and the battery status parameter data, dynamically adjust the output power of the charging unit at each charging position in the mobile drone nest to achieve closed-loop charging in the constant current charging stage and constant voltage charging stage mode.

[0074] The common charging mode for mobile drones is constant current in the early stage and constant voltage at the end. When a drone completes an inspection mission and returns to base within a certain timeframe, it consumes a significant amount of power. Therefore, in the initial charging phase, a constant current is used to quickly charge the battery until the battery voltage approaches a preset value. This constant current charging phase rapidly replenishes the battery's power, shortening the charging time. Once the battery voltage reaches the preset value, the charging unit switches to constant voltage charging mode, at which point the current gradually decreases until charging is complete. This constant voltage charging phase helps to finely adjust the battery's state, ensuring the battery is not overcharged. However, as the battery gradually charges, its impedance to the current changes continuously. During wireless charging, especially during the mode transition, this change in load impedance, combined with the slight changes in the drone's flight attitude and altitude during the charging docking process, which cause changes in the coil coupling coefficient, can lead to impedance mismatch in the charging system. This not only significantly reduces charging efficiency but may also cause voltage fluctuations and potentially damage the equipment.

[0075] Accordingly, this application first determines the preset charging amount of each airborne battery when charging based on the inspection task of the UAV in the next stage; then, the charging parameters are dynamically adjusted based on real-time monitoring data.

[0076] First, the remaining battery power of each drone at the moment it completes the previous stage of inspection and returns to land at the designated location of the mobile nest is used as the starting charge power.

[0077] Secondly, based on the inspection tasks assigned to each drone in the next time period, after determining the starting point and set flight trajectory, the energy consumption of the drone is assessed to determine the power required for inspection in the next time period. Considering the matching degree between power consumption and energy consumption during actual flight, a 5%-10% redundancy mechanism is set to ensure that the drone can complete the inspection task in the next time period after charging. Here, taking 5% redundancy as an example, the power required for inspection in the next time period is increased by 5% as the target charging amount.

[0078] It should be noted that when the adjusted result exceeds the maximum battery capacity, the maximum battery capacity will be used as the target charging amount; 80%-85% of the target charging amount will be used as the preset charging amount during charging.

[0079] Next, based on the DC voltage and current output from the power source in the mobile nest, the DC power of the power source in the mobile nest is calculated as the DC power that can be provided to all charging sources at each moment. Then, based on the number of all charging units connected to the onboard wireless charging device and the difference between the preset charging amount and the initial charging amount, the DC power allocated to the charging units for the drone to be charged is determined. The DC power allocated to the charging units for the drone to be charged is expressed as... :

[0080]

[0081] In the formula, This indicates the preset charging amount of the onboard battery of the drone to be charged; This indicates the initial charging charge level of the onboard battery of the drone to be charged. This represents the preset charging amount of the drone's battery connected to the a-th charging unit. This represents the initial charging capacity of the drone's battery connected to the a-th charging unit, N represents the number of charging units participating in battery charging, and W is the DC power of the power source in the mobile drone nest.

[0082] Finally, at each charging moment, the ratio of the DC power received by the receiving coil to the DC power of the charging unit where the transmitting coil, which is electromagnetically coupled to the receiving coil, is located is used as the transmission efficiency at each charging moment during the charging process of the UAV's onboard battery.

[0083] On the one hand, when a drone lands or hovers to charge, the slight fluctuations in its flight altitude will change the coil spacing, resulting in real-time changes in mutual inductance and coupling coefficient; on the other hand, the drone's attitude angle during charging will also affect the alignment of the transmitting coil of the charging unit and the receiving coil on the drone's onboard wireless charging device.

[0084] Therefore, in this application, the vertical distance between the transmitting coil and the receiving coil is obtained by using a barometer or ultrasonic radar on the UAV. The coupling coefficient at the vertical height is determined based on the fitting curve of the vertical distance and the coupling coefficient. The larger the vertical distance, the smaller the coupling coefficient. The fitting curve can be obtained by fitting the vertical distance between the transmitting coil and the receiving coil during the hovering process of the UAV multiple times. This is a well-known technology, and the specific process will not be described in detail.

[0085] The larger the deviation angle between the attitude angle (obtained by the drone's inertial sensors) and the optimal attitude angle (the attitude angle when the two coils are perfectly aligned, i.e., when the magnetic field coupling is aligned), the lower the magnetic field coupling efficiency.

[0086] Here, a first constraint index A is constructed for charging the drone's onboard battery, reflecting the degree of influence of the drone itself on the wireless charging process. The larger the first constraint index, the greater the influence. The expression is as follows:

[0087]

[0088] In the formula, This indicates the drone's attitude angle at the initial moment of charging. Indicates the optimal attitude angle; This represents the coupling coefficient corresponding to the vertical distance between the transmitting coil and the receiving coil at the initial moment of charging. This represents the theoretical maximum value of the coupling coefficient. The value is 1.

[0089] Furthermore, while the high current during the constant current charging phase increases charging speed, maintaining it for an extended period accelerates the depletion of electrode active materials. Therefore, the more battery charging cycles there are, the greater the cumulative effect of electrode active material depletion caused by prolonged constant current charging. In other words, the more battery cycles there are, the shorter the duration of the constant current charging phase should be, switching to the constant voltage charging phase earlier to reduce the current in a short time and ensure charging efficiency.

[0090] Here, a second constraint index B is constructed for charging the drone's onboard battery to reflect the degree of influence of the battery itself on the wireless charging process. The larger the second constraint index, the greater the influence. The expression is as follows:

[0091]

[0092] In the formula, This represents an exponential function with the natural constant as the base, where N represents the number of charging units involved in battery charging. This indicates the maximum battery health level. 100%, The battery health of the drone at the initial moment of charging.

[0093] The purpose of using an exponential function is to avoid the number of charging cycles having too much influence on the calculation results. Since the number of cycles is a positive integer, the larger N is, the greater the influence from the other charging units becomes when powering multiple units simultaneously. The value range of is (0,1], and a negative mapping is performed through the exponential function, making The range of values ​​for is (0,1), and the range of values ​​for B is also (0,1), consistent with that for A.

[0094] Furthermore, a control signal is dynamically generated using a PID controller by combining transmission efficiency, the first constraint index, the second constraint index, and real-time monitoring data. Higher transmission efficiency indicates higher battery charging efficiency and stronger system resistance to interference. Larger values ​​for the first and second constraint indices indicate a greater impact from the initial charging moment on the drone and battery's electromagnetic coupling during subsequent charging, resulting in greater system oscillations.

[0095] Secondly, by combining the transmission efficiency change trend characteristics of each charging moment and several previous historical charging moments during the charging process, the parameters in the PID controller at each charging moment are adaptively determined.

[0096] In this application, M preset historical charging times are obtained for each charging moment, where M is the preset number of historical charging times, and the value is set to 5. The transmission efficiency of the current charging moment and the M previous historical charging moments are arranged in chronological order. The arrangement results are fitted with a straight line. The closer the slope of the fitted line is to 1, the more stable the charging efficiency is. If the slope is less than 1, it indicates that the transmission efficiency is gradually decreasing. At this time, the integral term should be reduced to eliminate accumulated charging interference. If the slope is greater than 1, it indicates that the transmission efficiency is gradually increasing, and the possibility of being in the constant current charging stage is greater. At this time, the proportional and derivative terms should be increased to improve the system response speed and avoid oscillation.

[0097] To ensure the speed of dynamic adjustment of charging power, this application determines the parameter adjustment rules for each charging moment during the charging process based on the magnitude of the slope: when the slope is less than 1, only the integral term is adjusted; when the slope is greater than 1, the proportional term and the derivative term are adjusted in sequence; when the slope is equal to 1, no adjustment is made.

[0098] Specifically, taking time t as an example, the proportional, integral, and differential terms adjusted at time t during the charging process of the a-th charging unit for the drone's onboard battery are respectively expressed as follows: , , :

[0099]

[0100]

[0101]

[0102]

[0103] In the formula, This represents the adjustment step size at time t during the charging process of the a-th charging unit. t represents the start time of the charging of the drone's onboard battery by the a-th charging unit, and t represents the current time.

[0104] This represents the slope of the fitted straight line at time t during the charging process of the a-th charging unit; It is the normalized value of the sum of the first constraint index and the second constraint index when the a-th charging unit charges the onboard battery of the drone, wherein the normalized value is calculated by the ratio of the sum to the sum in N charging units. , , Let represent the proportional term, integral term, and differential term at time t-1 during the charging process of the a-th charging unit, respectively. In this application, the empirical ranges for the initial values ​​of the proportional term, integral term, and differential term are 0.1-10, 0.01-0.1, and 0-0.1, respectively; here, the values ​​are taken as 0.1, 0.6, and 0, respectively.

[0105] in, The larger the value, the closer the charging time of the a-th charging unit is to the preset charging time required. This indicates that the closer time t is to the charging mode switching time, the more the parameters should be adjusted slightly to ensure the stability of the PID controller; further reduce oscillation and ensure the reliability of the determined target phase shift angle value.

[0106] Furthermore, the difference between the transmission efficiency and the rated transmission efficiency of each charging unit at each charging moment is calculated, and the controller parameters of each charging unit at each moment are input. The PID controller outputs the target phase shift angle value. Based on the target phase shift angle value, the phase shift angle of the transmitter inverter of each charging unit in the mobile battery cell is adjusted, and the charging power of each charging unit when charging the onboard battery is dynamically adjusted to achieve closed-loop charging in constant current charging stage—constant voltage charging stage mode.

[0107] When the drone reaches its designated charging location, the inverter in the mobile drone housing converts the DC power supply into high-frequency AC power, driving the transmitting coil to generate an alternating magnetic field. The receiving coil generates AC power through magnetic coupling. This AC power then passes through a rectifier and a step-down converter to efficiently transfer electrical energy and charge the battery. The process of dynamically adjusting the inverter's phase shift angle based on the PID control signal is as follows:

[0108] S1, the inverter built into the mobile unit converts the DC power output into AC power, and uses Fourier transform to obtain the DC voltage. With inverter output voltage Expressions between:

[0109]

[0110] In the formula, This represents the phase shift angle of the inverter.

[0111] S2, according to Kirchhoff's laws, describes the circuit model between the transmitting coil and the receiving coil:

[0112]

[0113]

[0114] In the formula, This indicates the equivalent load of the circuit containing the receiving coil; , These are the inductances of the circuits containing the transmitting coil and the receiving coil, respectively. , These are the compensation capacitors for the circuits containing the transmitting coil and the receiving coil, respectively. , These are the effective values ​​of the currents in the circuits containing the transmitting and receiving coils, respectively; M represents the mutual inductance between the transmitting and receiving coils. Indicates angular frequency;

[0115] Furthermore, based on the circuit calculation relationships described above, the phase shift angle... The relationship between the output charging current and the output charging current is:

[0116]

[0117] Phase shift angle The relationship between the output charging voltage and the output charging voltage is as follows:

[0118]

[0119] In the formula, This represents the equivalent resistance of the battery during charging.

[0120] S3, Substitute the target phase shift angle value output by the PID controller into the relationship between the output charging current and the output charging voltage to obtain the corresponding target current and target voltage; compare the target phase shift angle with the phase shift angle at the current moment. The difference is calculated to obtain the adjustment amount. Based on the adjustment of the phase shift angle, the PWM drive signal of the inverter is generated, which changes the on and off time of the switching transistor, thereby changing the amplitude of the output voltage or current to the target voltage and target current, respectively.

[0121] The various embodiments in this application are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0122] It should be noted that, unless otherwise specified and limited, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a circuit structure, article, or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such article or device. Without further limitations, an element defined by the phrase “comprising one…” does not exclude the presence of other identical elements in the article or device that includes said element. Furthermore, the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0123] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not invented in this application.

[0124] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. An airborne wireless charging method for an overhead power line inspection drone, characterized in that, The method includes: By analyzing the difference between the initial charging power of the drone to be charged and the preset charging value, the DC power of the power source in the mobile drone housing is used to allocate DC power to the charging unit of the drone to be charged, so as to obtain the transmission efficiency during the charging process of the drone's onboard battery. By utilizing the deviation angle between the attitude angle of the drone during charging and the optimal attitude angle, as well as the alignment and coupling of the transmitting coil of the charging unit and the receiving coil on the drone's onboard wireless charging device, the first constraint index A during drone onboard battery charging is determined. The second constraint index B during drone onboard battery charging is determined by using the number of charging units involved in battery charging and the battery health at the initial moment of drone charging. The adjustment step size at each charging moment is set by using the average of the first and second constraint indices. Combined with the trend characteristics of the transmission efficiency change during the charging process of the UAV's onboard battery, the parameter adjustment rules in the PID controller at each charging moment are constructed. The difference between the transmission efficiency and the rated transmission efficiency at each charging moment is used as input, and the control signal is dynamically generated by the PID controller. The expression for the first constraint index A is: In the formula, This indicates the drone's attitude angle at the initial moment of charging. Indicates the optimal attitude angle; This represents the coupling coefficient corresponding to the vertical distance between the transmitting coil and the receiving coil at the initial moment of charging. This represents the theoretical maximum value of the coupling coefficient. The expression for the second constraint index is as follows: In the formula, This represents an exponential function with the natural constant as the base, where N represents the number of charging units participating in battery charging. This indicates the maximum battery health level. The battery health of the drone at the initial charging moment; The parameter adjustment rules include: A linear fit is performed on the transmission efficiency at the current charging moment and the M preset historical charging moments before it; When the slope of the fitted line is less than 1, the integral term is adjusted; When the slope of the fitted line is greater than 1, the proportional and differential terms are adjusted sequentially. When the slope of the fitted line is equal to 1, no adjustment is made.

2. The airborne wireless charging method for an overhead power line inspection drone as described in claim 1, characterized in that, The method for allocating DC power to the charging unit for charging the drone to be charged is as follows: Calculate the proportion of the difference in power between the initial charging power of the drone to be charged and the preset charging value to the total power difference of all drones to be charged. The product of the ratio and the DC power of the power source in the mobile nest is used as the DC power allocated to the charging unit for the drone to be charged.

3. The airborne wireless charging method for an overhead power line inspection drone as described in claim 2, characterized in that, The preset charging amount is used as a power indicator during mode switching between the constant current charging stage and the constant voltage charging stage, and is obtained through a preset ratio of the target charging amount.

4. The airborne wireless charging method for an overhead power line inspection drone as described in claim 1, characterized in that, The method for determining the coupling coefficient corresponding to the vertical distance between the transmitting coil and the receiving coil at the initial charging moment is as follows: Collect the vertical distance between the transmitting and receiving coils during the drone's hovering process and perform curve fitting; Obtain the coupling coefficient corresponding to the vertical distance between the transmitting coil and the receiving coil at the initial charging moment on the fitted curve.

5. The airborne wireless charging method for an overhead power line inspection drone as described in claim 1, characterized in that, The setting expression for the adjustment step size at each charging moment is: In the formula, This represents the adjustment step size at time t during the charging process of the a-th charging unit. t represents the start time of the charging of the drone's onboard battery by the a-th charging unit, and t represents the current time. It is the normalized value of the sum of the first constraint index and the second constraint index when the a-th charging unit charges the onboard battery of the drone.

6. The airborne wireless charging method for an overhead power line inspection drone as described in claim 1, characterized in that, The proportional, integral, and differential terms adjusted at time t during the charging process of the a-th charging unit for the drone's onboard battery are respectively expressed as follows: , , : In the formula, This represents the slope of the fitted straight line at time t during the charging process of the a-th charging unit; , , Let represent the proportional term, integral term, and differential term at time t-1 during the charging process of the a-th charging unit, respectively.

7. An airborne wireless charging device for an overhead power line inspection drone, characterized in that, For implementing the airborne wireless charging method for an overhead power line inspection drone as described in any one of claims 1-6, the device comprises: The battery status monitoring module is used to collect real-time status parameter data of the drone's onboard battery; Data analysis module; used to analyze the received battery status parameter data and charging unit data; The control module has a built-in PID controller, which is used to adaptively adjust the parameters in the PID controller based on the real-time data analysis indicators of the data analysis module. Based on the control signal generated by the PID, the inverter phase shift angle is dynamically adjusted to adjust the charging power of each charging unit when charging the drone's onboard battery. The data exchange module is used to synchronize the monitoring data of this device with the monitoring data of the mobile charging unit on the cell side to the control module; The communication module is used for bidirectional transmission of control commands and status parameter data with the mobile housing; The receiving coil, loosely coupled to the transmitting coil of the cell, is used to convert the high-frequency magnetic field into alternating current. The compensation module adopts a series-parallel hybrid topology for reactive power compensation and to improve the power factor. A rectifier is used to convert AC power, after compensation by a compensation module, into DC power. A buck converter is used to regulate and adjust the voltage of the rectified output to meet battery charging specifications. The protection module is used to actively disconnect the charging circuit when the temperature exceeds the limit, the duration exceeds the limit, or abnormal parameters occur. External interface for exporting inspection data, firmware upgrades, and function expansion.

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