Unmanned aerial vehicle stratosphere wireless charging method

Abstract

The invention relates to the technical field of wireless energy transmission, and discloses an unmanned aerial vehicle stratosphere wireless charging method, which comprises the following steps: before the method is implemented, carrying out microwave energy transmission tests under various environmental conditions, arranging a microwave signal transmitting device on the ground or a floating platform, and generating a microwave signal for transmitting energy to a target unmanned aerial vehicle, and controlling the propagation direction of the microwave signal, enabling the microwave signal to be focused on the target unmanned aerial vehicle in a directional manner, receiving the microwave signal by a microwave receiving device on the unmanned aerial vehicle, rectifying and converting the microwave signal into direct-current electric energy, and inputting the direct-current electric energy into an energy storage system of the unmanned aerial vehicle through a battery management module. According to the invention, a microwave and solar energy dual-energy power supply cooperative scheduling mechanism is adopted, intelligent switching and dynamic balance of energy paths are realized, the energy utilization efficiency is improved, and the bottleneck of continuous charging stability dependence is relieved.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless energy transmission, and particularly to a method for wireless charging of an unmanned aerial vehicle (UAV) in the stratosphere. Background Art

[0002] In the fields of high-altitude long-endurance flight platforms, communication relay systems, meteorological detection, etc., UAVs are gradually extending to the stratosphere. The traditional energy replenishment method relying on returning for charging at low altitudes is no longer applicable at this altitude. Energy acquisition has become the core problem restricting mission sustainability. Especially for aircraft that need to hover for a long time or cruise slowly, how to achieve remote energy replenishment without interrupting the mission directly determines its practicality.

[0003] In the prior art, some solutions have utilized microwave wireless energy transmission for remote power supply. The transmitting system can complete energy transfer within a specific distance through a fixed beam method. The technical route using phased array antennas can achieve medium and long-distance transmission and has good direction control capabilities. Some other studies have explored deploying solar panels on the surface of the aircraft to achieve passive energy collection for extending flight time.

[0004] However, when facing the continuous energy replenishment requirements in the high-altitude environment, the above methods expose various unavoidable shortcomings. Microwave transmission schemes generally lack dynamic tracking capabilities. When the target deviates, the energy reception significantly decreases, and the risk of system failure increases. Most control logics ignore the actual impact of flight states and environmental factors on power output, with a rough adjustment mechanism and poor adaptability. Some technologies use solar power supply, but it is disconnected from the main energy module, and the switching mechanism is rigid, unable to achieve true collaborative work. More critically, existing solutions usually set parameters in static or near-ground tests. After entering the stratosphere, they lack real-time feedback and closed-loop adjustment capabilities, with poor power stability, resulting in a decline in energy efficiency. For this reason, those skilled in the art have proposed a method for wireless charging of UAVs in the stratosphere to solve the above problems. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a method for wireless charging of UAVs in the stratosphere, which solves the problems of the lack of dynamic tracking and regulation mechanisms in the process of microwave energy transmission, the failure to synergistically utilize solar and microwave energy in the power supply system, and the insufficient charging stability in the complex high-altitude environment in the prior art.

[0006] To achieve the above objectives, the present invention is realized through the following technical solutions: A method for wireless charging of UAVs in the stratosphere includes the following steps:

[0007] Before the implementation of the method, perform microwave energy transmission tests under various environmental conditions to evaluate signal loss and reception stability under different altitudes, temperatures, pressures, and flight states, and optimize the system parameter configuration based on the test results;

[0008] A microwave signal transmitting device is set on the ground or floating platform to generate microwave signals for transmitting energy to the target unmanned aerial vehicle (UAV).

[0009] Control the propagation direction of the microwave signal so that the microwave signal is directionally focused on the target UAV.

[0010] The microwave receiving device on the UAV receives the microwave signal and rectifies it into direct current (DC) electrical energy.

[0011] Input the DC electrical energy into the energy storage system of the UAV through the battery management module.

[0012] When the lighting conditions permit, collect energy through the solar panel to provide auxiliary power supply and conduct power supply path scheduling with the microwave charging system.

[0013] Based on the feedback of the UAV flight state and environmental parameters, adjust the microwave transmission power, beam direction and signal frequency in real time to achieve dynamic charging control.

[0014] Preferably, the microwave signal transmitting device includes:

[0015] A solid-state microwave source with an output frequency between 10 gigahertz and 30 gigahertz.

[0016] A microwave modulation module for frequency modulation, phase modulation and amplitude modulation.

[0017] A phased array antenna composed of at least 16 array units, and each unit has an independent phase control ability.

[0018] Preferably, the spacing between the array units is half of the wavelength corresponding to the operating frequency.

[0019] Preferably, the microwave receiving device includes:

[0020] A microwave receiving antenna for receiving the microwave signal from the transmitting device and outputting an alternating current (AC) signal.

[0021] A rectification module composed of at least four parallel Schottky diodes.

[0022] An energy storage unit, which is electrically connected to the output end of the rectification module and connected to the battery management module.

[0023] Preferably, the forward conduction voltage of the Schottky diode is not higher than 0.3 volts.

[0024] Preferably, the battery management module includes:

[0025] A power calculation unit for calculating the instantaneous power value according to the rectified output voltage and current.

[0026] The maximum power point tracking control unit adjusts the equivalent output impedance of the rectification module through the perturbation-observation algorithm or the incremental conductance algorithm;

[0027] The controller adjusts the impedance matching parameters according to the power change trend to keep the output power near the maximum point.

[0028] Preferably, the feedback of the flight state and environmental parameters includes:

[0029] Flight altitude, speed, pitch angle, received signal strength, atmospheric temperature and humidity, and target position;

[0030] The parameters are collected by the multi-sensor module on the UAV and sent to the microwave transmission control center through the communication module;

[0031] The control center dynamically adjusts the microwave transmission direction, output power, and signal frequency based on the feedback parameters.

[0032] Preferably, the adjustment of the signal frequency includes:

[0033] The control center selects the operating frequency with the least interference from a set of preset frequencies;

[0034] When it is detected that the current frequency interference value exceeds the threshold, switch to another frequency for transmission;

[0035] The interval time for each frequency switch does not exceed 500 milliseconds.

[0036] Preferably, the solar-assisted power supply includes:

[0037] Solar panels with a photoelectric conversion efficiency of not less than 18% are arranged on the surface of the UAV body;

[0038] The control module detects the solar voltage value and preferentially uses solar power when it is higher than the set threshold;

[0039] When the voltage is lower than the threshold, switch to the microwave energy receiving module for power supply.

[0040] Preferably, the microwave energy transmission test includes the following steps:

[0041] Under conditions of not less than three flight altitudes, measure the microwave transmission loss and received signal strength respectively;

[0042] Evaluate the signal stability and antenna beam focusing ability under different environmental temperature and humidity and atmospheric rarefaction conditions;

[0043] Adjust the parameters of the transmission module, the structure of the receiving antenna, and the configuration of the control strategy parameters according to the test results.

[0044] The present invention provides a method for wireless charging of drones in the stratosphere. It has the following beneficial effects:

[0045] 1. The present invention adopts a "microwave and solar energy" dual-energy power supply collaborative scheduling mechanism, realizing intelligent switching and dynamic balance of the energy path. Compared with the single microwave energy transmission scheme in the prior art, which has problems of energy waste or system standby in scenarios where sunlight can be utilized, it improves the energy utilization efficiency and alleviates the bottleneck of relying on continuous charging stability.

[0046] 2. The present invention adopts a maximum power point tracking (MPPT) control strategy combined with an impedance matching parameter adaptive adjustment mechanism, enabling the system to maintain a state close to the maximum power output during the dynamic process of power change. Compared with the power output fluctuation problem of traditional fixed impedance systems in high-dynamic flight states, the present invention enhances the power stability and response sensitivity of the system without adding additional complex hardware loads.

[0047] 3. The present invention realizes precise focusing and dynamic direction adjustment of microwave beams in space by introducing a phased array antenna at the transmitting end and supplementing it with multi-dimensional environmental feedback parameter control. The traditional fixed-direction transmitting structure is vulnerable to flight deviation and atmospheric disturbance, resulting in alignment failure. This solution not only ensures energy focusing but also greatly improves the robustness of energy tracking and locking, and improves the high-altitude fixed-point energy docking ability.

[0048] 4. The present invention optimizes the parameter configuration of the microwave system through multi-environment test data feedback, especially conducts adaptation verification under extreme conditions such as high altitude, low air pressure, and strong ultraviolet rays. Different from the traditional scheme of general ground debugging and deployment, it conducts pre-treatment design for the technical implementation difficulties of stratospheric applications, avoiding system instability caused by insufficient environmental adaptability from the source and improving practical reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic flow chart of the method of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0050] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0051] Please refer to the attached Figure 1 , the embodiments of the present invention provide a method for wireless charging of drones in the stratosphere, including the following steps:

[0052] S1. Before implementing the method, perform microwave energy transmission tests under various environmental conditions to evaluate signal loss and reception stability at different altitudes, temperatures, air pressures, and flight states, and optimize the system parameter configuration based on the test results.

[0053] Specifically, in this embodiment, first, microwave energy transmission tests were conducted on the wireless charging system of the present invention under various environmental conditions. The purpose of this test is to evaluate the influence of environmental factors such as different flight altitudes, temperatures, air pressures, and humidities on the system performance, especially the transmission efficiency and stability of microwave signals. Through such tests, the system parameter configuration can be optimized to ensure stability and efficiency under different flight states.

[0054] Generally, during flight, the flight altitude and meteorological conditions of the unmanned aerial vehicle (UAV) will affect the propagation of microwave signals. Therefore, it is necessary to optimize various parameters of microwave energy transmission according to environmental conditions. For example, at different flight altitudes, the attenuation characteristics of signals are different, and changes in atmospheric temperature, humidity, and air pressure will cause a certain degree of deviation in the signal propagation path. For this reason, in this embodiment, multiple rounds of environmental simulations and actual measurements were carried out under different air pressure, temperature, humidity, and wind speed conditions, covering three flight altitude gradients of 15 km, 18 km, and 20 km.

[0055] Specifically, during the test, detailed measurements of the transmission loss, reception beam stability, and conversion efficiency of microwave signals were carried out for the flight environment at each altitude. The measured data show that when the flight altitude reaches 20 km, the transmission attenuation of microwave signals is the smallest, the reception stability is the strongest, and at the same time, the conversion efficiency is also higher than that at other altitudes. In addition, in the stratosphere environment at this altitude, the frequency band of microwave signals has the best adaptability to the environment. By comparing the performance of different frequency bands, it is found that the transmission efficiency of the 20 GHz frequency band is the most stable and the interference is the smallest.

[0056] In a possible implementation manner, the frequency range of the solid-state microwave source of 18 - 22 GHz was finally determined. Based on these test data, the following formula can be derived to calculate the transmission loss of microwave signals:

[0057]

[0058] Where: L is the signal attenuation (unit: dB); d is the transmission distance; f is the signal frequency; α is the additional loss caused by environmental factors; d0 and f0 are the reference distance and frequency respectively.

[0059] Through experimental verification, the values of each parameter in the above formula were determined, and the setting of the α value considered the influence of different environmental temperature, humidity, and rarefaction conditions of the atmosphere.

[0060] As an option, in order to further improve the focusing ability and reception effect of the signal, a phased array antenna system is adopted in this embodiment. The gain value of the phased array antenna is set to 35 dBi to optimize the signal transmission and focusing ability. By adjusting the phase and amplitude of each array unit, directional energy transmission can be achieved, avoiding signal loss and interference.

[0061] Generally, through the above-mentioned test and optimized parameter configuration, the complexity of system debugging can be minimized to the greatest extent, and the stability and high performance of the system in subsequent practical applications can be ensured. The test results provide a reliable technical basis for the energy transmission of the drone during flight in the stratosphere, avoiding repeated adjustments and possible system failures, thereby improving the reliability and deployment efficiency of the system.

[0062] S2. Set up a microwave signal transmitting device on the ground or floating platform to generate microwave signals for transmitting energy to the target drone;

[0063] Specifically, after completing the optimization of microwave transmission parameters and environmental adaptability tests, in order to achieve efficient energy transmission from the ground to stratospheric drones, the present invention further constructs a microwave energy transmitting device with beam controllability, stable output power, and fast response. The core of this step lies in completing the construction of the ground microwave system and the configuration of each functional module to ensure that the system has the beam emission ability of high gain, strong directivity, and low delay.

[0064] In this embodiment, the microwave energy transmitting device is arranged at the ground station, and the overall structure is composed of a signal source module, a power amplification module, a feeding network module, an antenna array module, and a main control and scheduling unit. Signals are transmitted between modules through RF connection lines or waveguides, and the signal waveforms are amplified and shaped step by step according to functions, and finally the emission of microwave energy in space is completed.

[0065] In a possible implementation manner, the signal source module adopts a local oscillator signal source with phase synchronization to generate an excitation signal with a stable frequency range between 18 - 22 GHz. This frequency range is consistent with the optimized test results of the receiving end, which is beneficial to maximizing the space energy transmission efficiency. The signal source is divided into multiple equal-amplitude signal channels through a splitter and then input into the solid-state power amplifier array.

[0066] The solid-state power amplification module is composed of multiple GaN-based power amplifiers. The maximum output power of each channel is 12 W, and the output end is equipped with a standing wave protection circuit to reduce the problem of system stability degradation caused by reflection at the antenna feed end. Generally, the output signals amplified by multiple channels need to maintain phase consistency, so a fine-tuning phase shifter is introduced into the feeding network to precisely adjust the phase of each channel, and the error is controlled within ±0.2°.

[0067] The power feeding network module adopts a low-loss waveguide structure to guide the outputs of each channel to the two-dimensional phased array antenna elements. The array antenna is an 8×8 array with a total of 64 transmitting elements, and the array arrangement adopts a square compact layout. Each antenna element is of a microstrip patch structure, with good directivity and frequency response characteristics, a center frequency of 20 GHz, and a bandwidth of 2 GHz.

[0068] Specifically, the spacing between the array antenna elements is set to λ / 2, where λ is the free space wavelength corresponding to the center frequency, that is:

[0069]

[0070] where: λ represents the wavelength (unit: m); c represents the speed of light constant, with a value of 3×10 8 m / s; f is the transmission frequency (unit: Hz).

[0071] Through this setting, the sidelobe interference outside the main lobe can be effectively suppressed, and the directivity gain can be improved.

[0072] In a specific implementation scheme, the phased array has the ability of fast beam pointing and can complete the switching of the main lobe direction from the initial angle to the target angle within no more than 0.5 seconds. The beam control adopts digital phased technology, and the phase delay of each unit is controlled in real time through the FPGA main control chip, so as to realize the beam reconstruction in any direction.

[0073] As an option, the system also introduces a beam pre-alignment module. Based on the predicted information of the UAV position, the module receives the flight trajectory signal (such as GPS coordinates) on the ground and cooperates with meteorological models such as wind speed and direction to estimate the spatial position of the UAV several seconds in advance. According to the prediction result, the system automatically completes the preliminary adjustment of the emission beam direction.

[0074] In some embodiments of the present invention, to ensure that the beam adjustment does not affect the overall emission state of the system, the drive parameters of each array unit are uniformly scheduled by the main control system and have a self-calibration function. When there are device temperature drifts or external interferences, the system can call the reference signal to re-adjust the phase to avoid beam deviation.

[0075] In addition, to improve the system emission efficiency, the calculation expression of the total microwave emission power P T in this embodiment is defined as follows:

[0076] P T = N·P u ·η a ;

[0077] where; P T is the total output power of the emission array (unit: W); N is the total number of array units; P uis the unit output power; η a is the array coupling efficiency, representing the effective transfer efficiency of energy from the amplifier to the antenna port, and usually takes values in the range of 0.85 to 0.95.

[0078] Through the above structural design and control logic configuration, the present invention can perform high-directional microwave energy emission operations on target UAVs in the airspace above 20 kilometers. In subsequent steps, the system will further combine the UAV position status data to achieve real-time beam adjustment and directional tracking.

[0079] S3. Control the propagation direction of the microwave signal to make the microwave signal directionally focus on the target UAV;

[0080] Specifically, after the construction of the microwave signal transmitting device and parameter optimization are completed, the system enters the key step S3 to control the propagation direction of the microwave signal to make the microwave signal directionally focus on the target UAV. The goal of this step is to achieve efficient and accurate energy transmission. By dynamically controlling the beam direction of the microwave signal, it is ensured that the microwave signal can be accurately focused on the target UAV and continuously and stably provide energy for it.

[0081] In this embodiment, the system uses the aforementioned phased array antenna and beam pointing technology to achieve the directional control of the microwave signal by adjusting the phase difference of the antenna array in real time. Specifically, the directional control of signal transmission depends on the real-time tracking and prediction of the position of the target UAV. Combining the flight control system data, dynamic beam adjustment is carried out. Through this process, the system can accurately guide the energy flow to the target, avoid energy waste and maximize the transmission efficiency.

[0082] Generally, the flight path of the target UAV will be affected by different meteorological factors (such as wind speed, air pressure, etc.). Therefore, the system needs to have efficient real-time data processing and beam adjustment capabilities. In some embodiments, by integrating the real-time position information, flight speed and attitude data of the UAV, and combining the prediction module of the ground control station, the system can predict the flight trajectory of the UAV. Through the trajectory prediction of the UAV, the beam direction of the microwave transmitting device can be calculated and adjusted in advance, so that the microwave signal can be focused on the position of the UAV at the correct time.

[0083] Specifically, this embodiment adopts the phased array antenna technology, which uses multiple antenna units to cooperate together to control the beam direction by adjusting the phase and amplitude of each unit. The transmitted signal of each antenna unit will be adjusted according to a set phase difference and amplitude, so that the overall beam is focused on the target direction. In the process of microwave signal transmission, the precise control of the phased array antenna is crucial to ensure the effective transmission of energy.

[0084] In a possible implementation, the system adopts a real-time beam pointing algorithm, combines information such as the dynamic position, flight speed, and attitude angle of the target UAV, and makes dynamic adjustments. Assuming the flight position of the target UAV is (x u , y u , z u ), the adjustment formula for the beam pointing can be expressed as:

[0085]

[0086] Where: θ is the direction angle of the beam on the horizontal plane; φ is the angle of the beam in the vertical direction; x u , y u , z u are the position coordinates of the target UAV in three-dimensional space respectively.

[0087] Through this formula, the system can calculate the position change of the target UAV in real time, and accurately adjust the pointing of the beam according to the flight trajectory of the UAV. This process not only requires the control system to respond quickly, but also requires high computing power and precise positioning technology.

[0088] As an option, in order to improve the anti-interference ability and positioning accuracy of the system, multi-sensor fusion technology is also introduced in this embodiment. By combining multiple data sources such as the GPS positioning of the UAV, the inertial navigation system (INS), and the radar signal of the ground station, the system can maintain accurate beam pointing under more complex environmental conditions.

[0089] Specifically, the system receives and processes multiple sensor signals in real time, uses the Kalman filter algorithm to estimate the state of the UAV, and further optimizes the beam adjustment strategy. The Kalman filter algorithm can effectively reduce noise interference, improve positioning accuracy, and ensure that the microwave signal is always accurately focused on the target UAV.

[0090] In some embodiments, if the UAV is in a relatively complex flight environment (such as high speed, sharp turning, etc.), the system will automatically adjust the beam pointing frequency and step accuracy according to the flight control data to ensure that the real-time adjustment of the beam does not cause system overload or instability.

[0091] S4. The microwave receiving device on the UAV receives the microwave signal and rectifies it into DC electric energy;

[0092] Specifically, after the transmission of the aforementioned microwave signal and the control of the beam direction are completed, the present invention enters the crucial step S4, that is, the microwave receiving device on the target UAV receives the microwave signal and rectifies it into direct current electrical energy. This step is the core link in the entire wireless charging process, determining the effective conversion and storage of microwave energy, thereby ensuring that the UAV can achieve continuous flight or perform tasks. Through efficient microwave energy reception and rectification conversion, the stability and reliability of the system in different flight states are ensured.

[0093] In this embodiment, the microwave receiving device is arranged on the target UAV and mainly consists of a receiving antenna, a rectifying circuit, a filter, and an electrical energy management module. The receiving antenna is responsible for receiving the microwave signal from the ground microwave transmitting device and converting it into radio frequency electrical energy. Through an efficient rectifying circuit, the radio frequency signal is converted into direct current, and high-frequency noise is removed through the filter, ultimately providing stable power support for the battery of the UAV or other energy storage devices.

[0094] Generally, the design of the microwave receiving device needs to consider different flight altitudes, speeds, and the strength of the received signal to ensure stable energy reception efficiency in different environments. In some embodiments, the receiving antenna adopts a dual-polarization structure, which can receive microwave signals with different polarization modes simultaneously, improving the reception efficiency. The size and shape of the receiving antenna are optimized according to the flight requirements of the UAV to adapt to different frequency bandwidths and flight states.

[0095] Specifically, the receiving antenna usually adopts a microstrip antenna or a spiral antenna structure. The microstrip antenna is very suitable for installation on the UAV due to its compact structure and light weight. To improve the reception efficiency, the operating frequency band of the antenna is consistent with the transmission frequency band of the microwave transmitting system. For example, in this embodiment, the system uses a frequency band range of 18–22 GHz, and the designed frequency of the receiving antenna is usually 20 GHz, which can minimize signal loss to the greatest extent.

[0096] After receiving the microwave signal, the main function of the rectifying circuit is to convert the radio frequency signal into stable direct current electrical energy. As an option, Schottky diode rectification technology is adopted in this embodiment. This technology has a low forward voltage drop and a high rectification efficiency, which can effectively improve the conversion efficiency. The rectifying circuit can describe its conversion efficiency through the following formula:

[0097]

[0098] where: η is the rectification conversion efficiency; P dc is the output direct current power; P rf is the received radio frequency signal power.

[0099] By optimizing the design parameters of the rectifier circuit, such as the selection of diodes, operating frequency, and circuit matching, the conversion efficiency can be maximized and energy losses can be reduced.

[0100] Specifically, in some embodiments, the rectifier circuit also incorporates power management technology to adapt to different power requirements of the drone. Through an intelligent power management system, it can dynamically adjust the power reception level of the microwave receiving device according to the current battery level and load requirements of the drone. This function ensures that when the drone has sufficient power, the system does not have to over-receive microwave energy, thus improving the energy usage efficiency of the system.

[0101] In a possible implementation, to further improve the rectification efficiency, this embodiment introduces a multi-stage rectification structure into the rectifier circuit. By combining parallel and series connections and cascading multiple rectification devices, the overall efficiency can be increased. This method can effectively reduce the efficiency decline caused by the loss of a single rectification unit.

[0102] As an option, to optimize the stability and service life of DC electrical energy, this embodiment also adds a voltage regulator at the output end. The voltage regulator can ensure the stability of the DC electrical energy output and prevent damage to the drone's battery system caused by voltage fluctuations.

[0103] Generally, the process of receiving microwave signals is accompanied by certain environmental interference. Therefore, this embodiment also incorporates anti-interference design. Through advanced frequency selection and adaptive filtering algorithms, it reduces interference caused by multipath propagation, meteorological factors, or other electromagnetic wave sources, thus further ensuring the effective transmission and stable reception of microwave energy.

[0104] S5. Input the DC electrical energy into the energy storage system of the drone through the battery management module;

[0105] Specifically, after receiving the microwave signal and rectifying it into DC electrical energy, the next key step is to input the DC electrical energy into the energy storage system of the drone through the battery management module. The goal of this step is to ensure that the power provided by microwave energy transmission can be effectively stored in the drone's battery system, and the battery status can be monitored and the electrical energy can be efficiently managed through the battery management module.

[0106] In this embodiment, the Battery Management System (BMS) is a key component. It is responsible for monitoring various parameters of the battery, such as the charging state, health state, temperature, etc., and dynamically adjusting the charging strategy according to the usage of the battery to ensure that the battery is charged within a safe range and the service life of the battery is extended. Through the BMS, the system can ensure that the current received through microwave energy can be input into the energy storage system of the drone at the appropriate time and speed, thus ensuring that the drone can fly continuously and stably.

[0107] Generally, the energy storage system of a drone needs to have the characteristics of fast charging, long life, and stable performance. Therefore, the battery management module not only needs to ensure the stability of the current and voltage during the battery charging process, but also needs to adjust the charging strategy according to the actual state of the battery. For example, if the battery is in a low power state, the BMS can increase the charging current to speed up the charging speed; conversely, when the battery is close to full charge, the BMS reduces the charging current to avoid overcharging.

[0108] Specifically, in this embodiment, the battery management module first monitors the received DC electrical energy and adjusts and adapts it to meet the input requirements of the battery energy storage system. The battery management module adjusts the DC power supply from the microwave energy receiving device to the working voltage range suitable for the drone battery through an efficient voltage and current regulation circuit.

[0109] In some embodiments, the battery management module also has an overcharge protection function. When the battery charge reaches the set threshold, the battery management module automatically cuts off the charging current to prevent damage caused by overcharging the battery. In addition, the BMS can also monitor information such as the temperature and internal resistance of the battery in real time and issue an alarm or initiate a protection measure in case of an abnormality.

[0110] As an option, in order to further improve the intelligence level of the battery management module, an algorithm based on machine learning is introduced in this embodiment. By learning the historical usage data of the battery, this algorithm can predict the future health state of the battery, and thus adjust the charging strategy and protection measures in advance according to the prediction results. For example, when the health state of the battery gradually deteriorates, the BMS can extend the effective service life of the battery by reducing the charging speed or adjusting the charging method.

[0111] Specifically, the battery management module also performs real-time battery monitoring during the charging process. It measures data such as battery voltage, current, and temperature through sensors, and updates the battery charging strategy in real time based on these data. By monitoring the SOC (State of Charge) and SOH (State of Health) of the battery, the system can detect in time whether there is a risk of overheating, overcharging, or over-discharging of the battery and perform automatic adjustment.

[0112] In a possible implementation, the working principle of the BMS can be described by the following battery charging efficiency formula:

[0113]

[0114] Where; η charge is the charging efficiency; P out is the electrical energy output by the battery; P in is the electrical energy received by the battery.

[0115] By optimizing the electrical energy regulation ability of the battery management module, the battery charging efficiency can be ensured to reach the optimum, avoiding energy waste.

[0116] As an option, this embodiment also adopts a battery balancing function to ensure that the voltages of each battery cell are relatively balanced, avoiding overcharging or over-discharging phenomena caused by battery imbalance. The battery balancing function dynamically adjusts the voltage differences of each battery cell through active or passive balancing strategies, thereby improving the stability and safety of the energy storage system.

[0117] S6. When the lighting conditions permit, collect energy through the solar panels to provide auxiliary power supply and perform power supply path scheduling with the microwave charging system;

[0118] Specifically, after completing microwave energy reception, rectification, and battery charging, the next step of the present invention is: when the lighting conditions permit, collect energy through the solar panels to provide auxiliary power supply and perform power supply path scheduling with the microwave charging system. This link further optimizes the energy utilization efficiency of the UAV by combining the complementary characteristics of solar energy and microwave energy, ensuring its ability to maintain long-term and stable flight under different environmental conditions.

[0119] In this embodiment, the solar panels serve as an auxiliary power supply source and, together with the microwave charging system, provide support for the UAV's energy storage system. The system realizes the coordinated scheduling of microwave energy and solar power through an intelligent power management module. In the case of sufficient lighting, the solar panels mainly charge the battery, while when the lighting conditions are insufficient, the system preferentially uses the microwave charging system to supply power to the battery. Through this intelligent scheduling strategy, while ensuring the battery charging efficiency, the service life of the microwave charging system can be extended, and the overall energy efficiency can be improved.

[0120] Generally, the output power of the solar panels is affected by lighting intensity, angle, and weather conditions. Therefore, the system needs to judge the working state of the solar panels based on real-time lighting data. The system obtains the lighting intensity information through built-in sensors and inputs it into the power management module to decide whether to enable the solar panels to charge according to the real-time lighting conditions.

[0121] Specifically, when the lighting conditions permit, the output power of the solar panel is proportional to the light intensity, and the power can be calculated by the following formula:

[0122] P solar = η solar ·A·I;

[0123] Where: P solar is the output power of the solar panel (unit: W); η solar is the efficiency of the solar panel; A is the area of the solar panel (unit: m 2 ); I is the light intensity per unit area (unit: W / m 2 ).

[0124] As an option, the installation angle and direction of the solar panel can be automatically adjusted according to the geographical location, time and seasonal changes to maximize the solar energy absorption efficiency. This angle adjustment can be automatically completed by the built-in electric control system and optimized according to the real-time lighting data.

[0125] When the lighting conditions are poor or cannot meet the charging requirements, the power management module in this embodiment will automatically switch to the microwave charging system to ensure that the charging requirements of the UAV energy storage system are met. At this time, the energy conversion of the microwave system will supplement the power shortage caused by insufficient lighting.

[0126] Specifically, the power management module will conduct power supply path scheduling by comprehensively considering the output power of solar energy and microwave charging according to the current charging state (SOC, State of Charge) of the battery and the estimated energy demand. When the output power of solar energy is insufficient, the system will switch to the microwave charging system and optimize the power supply path through the following algorithm:

[0127] P total = P solar + P microwave ;

[0128] Where: P total is the total power received by the battery (unit: W); P solar is the power provided by the solar panel; P microwave is the power provided by the microwave charging system.

[0129] Through intelligent scheduling, when the solar power is insufficient, the microwave charging system can provide supplementary power to ensure that the UAV energy storage system always remains within the safe charging range.

[0130] In a possible implementation, the power management module in this embodiment is also combined with a weather forecasting system to predict future lighting conditions and make early power scheduling decisions. Through real-time analysis of weather data, the system can estimate the lighting changes in the next few hours and adjust the cooperation mode of solar energy and microwave energy in advance to avoid affecting the energy supply of the UAV due to weather changes.

[0131] As an option, under extreme weather conditions, the power management module can also adjust the power supply strategy according to the urgency of the flight mission. For example, in bad weather, the system can give priority to using the microwave charging system to ensure that the energy requirements of the UAV are met first and avoid mission interruption.

[0132] S7. Based on the feedback of the UAV flight state and environmental parameters, the microwave transmission power, beam direction, and signal frequency are adjusted in real time to achieve dynamic charging control.

[0133] Specifically, after the coordinated operation of the microwave energy transmission and energy storage system is completed, the core task of step S7 is: the controller adjusts the impedance matching parameters according to the power change trend to keep the output power near the maximum point. The goal of this link is to ensure that the power transmission efficiency of the system reaches the optimum through precise impedance matching adjustment, avoid energy loss or equipment overload caused by impedance mismatch, and thus maintain the efficient and stable operation of the system.

[0134] In this embodiment, the controller adjusts the impedance matching parameters in the system by real-time monitoring of the power change trend and combining environmental factors (such as temperature, humidity, flight altitude, etc.). Impedance matching is a key link in the microwave energy transmission system. Good impedance matching can maximize the transmission efficiency of microwave signals, reduce the reflected power, and improve the overall performance of the system.

[0135] Generally, during the microwave energy transmission process, the impedance matching between the transmitter and the receiver will fluctuate due to environmental factors, equipment characteristics, etc. To maintain the maximum output power, the system needs to adjust the impedance between each component in real time to avoid signal reflection and power loss. Therefore, the impedance matching module will adjust the impedance between the microwave transmitting device and the receiving device according to the real-time feedback power data to keep it in the best working state all the time.

[0136] Specifically, the controller in this embodiment is based on the feedback loop control strategy and uses a power sensor and a signal analysis module to monitor the output power of the system in real time. The controller analyzes the power change trend and adjusts the parameters of the impedance matching network according to the power change curve, so that the system always operates near the maximum power point. The adjustment process of impedance matching can be described by the following formula:

[0137]

[0138] Where: P out is the output power (unit: W); V in is the input voltage (unit: V); R load is the load impedance (unit: Ω).

[0139] According to the above formula, the controller adjusts the matching of the input voltage and the load impedance according to the change trend of the power output, so as to maintain the maximization of the power output.

[0140] As an option, in order to further optimize the impedance matching process, this embodiment adopts an automated impedance adjustment network. This network uses capacitors, inductance, and adjustable resistor elements to dynamically adjust the electrical parameters in the impedance matching network through precise control algorithms. The adjustment of each electrical component is regulated by the controller according to the real-time data of the power sensor to ensure that the output power always remains near the maximum point.

[0141] Specifically, the controller adopts a closed-loop control strategy based on sensor feedback, measures the reflected power in real time during the transmission process, and adjusts the impedance matching network according to the reflection coefficient (S parameter). The reflection coefficient can be calculated by the following formula:

[0142]

[0143] Where: S 11 is the reflection coefficient; Z load is the load impedance; Z0 is the characteristic impedance of the transmission line.

[0144] By optimizing the reflection coefficient, the controller can ensure that the reflection loss is minimized, thereby maximizing the energy transmission efficiency.

[0145] In a possible implementation, the adjustment of the impedance matching can be completed by a high-precision digital controller. This controller can quickly and precisely adjust each component of the impedance matching network to cope with environmental changes or system state fluctuations. For example, the system may automatically adjust the impedance matching parameters according to factors such as temperature, humidity, or flight altitude to ensure that the system always operates in the best state.

[0146] As an option, the system can also combine artificial intelligence algorithms to predict the future power change trend based on historical data and real-time power feedback. The controller adjusts the impedance matching in advance by learning the law of power change to improve the response speed and adjustment accuracy. By introducing machine learning algorithms, the system can achieve more intelligent regulation and adapt to different flight missions and environmental conditions.

[0147] In general, this precise impedance matching control can significantly improve the stability and transmission efficiency of the system, reduce power losses caused by impedance mismatch, and ensure that the microwave energy transmission system can operate stably in different environments.

[0148] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for wireless charging of an unmanned aerial vehicle in the stratosphere, characterized in that The following steps are involved: Before the method is implemented, microwave energy transmission tests are conducted under various environmental conditions to evaluate signal loss and reception stability at different altitudes, temperatures, air pressures, and flight conditions, and the system parameter configuration is optimized based on the test results; A microwave signal transmitting device is set on the ground or on a floating platform to generate a microwave signal for transmitting energy to the target UAV; Control the propagation direction of microwave signals so that the microwave signals can be focused on the target UAV; The microwave receiving device on the UAV receives the microwave signal and rectifies and converts it into direct current power; Inputting the DC power into the energy storage system of the drone through a battery management module; When light conditions permit, the solar panels are used to collect energy to provide auxiliary power supply, and the power supply path is scheduled with the microwave charging system; Based on the UAV flight status and environmental parameter feedback, the microwave transmission power, beam direction and signal frequency are adjusted in real time to achieve dynamic charging control.

2. The method for wireless charging of an unmanned aerial vehicle in the stratosphere according to claim 1, wherein The microwave signal transmitting device comprises: Solid-state microwave sources having an output frequency between 10 GHz and 30 GHz; Microwave modulation module, used for frequency modulation, phase modulation and amplitude modulation; The phased array antenna consists of at least 16 array units, each of which has independent phase control capabilities.

3. A method for wireless charging of an unmanned aerial vehicle in the stratosphere according to claim 2, characterized in that, The spacing between the array units is half of the wavelength of the corresponding working frequency.

4. A method for wireless charging of an unmanned aerial vehicle in the stratosphere according to claim 1, characterized in that, The microwave receiving device comprises: A microwave receiving antenna, used to receive microwave signals from the transmitting device and output AC signals; A rectifier module, consisting of at least four Schottky diodes connected in parallel; The energy storage unit is electrically connected to the output end of the rectifier module and is connected to the battery management module.

5. A method for wireless charging of an unmanned aerial vehicle in the stratosphere according to claim 4, characterized in that, The forward conduction voltage of the Schottky diode is no higher than 0.3 volts.

6. A method for wireless charging of an unmanned aerial vehicle in the stratosphere according to claim 1, characterized in that, The battery management module comprises: A power calculation unit, used to calculate the instantaneous power value according to the rectifier output voltage and current; The maximum power point tracking control unit adjusts the equivalent output impedance of the rectifier module through a disturbance-observation algorithm or a conductance increment algorithm; The controller adjusts the impedance matching parameters according to the power change trend to keep the output power near the maximum point.

7. A method for wireless charging of an unmanned aerial vehicle in the stratosphere according to claim 1, characterized in that, The flight status and environmental parameter feedback includes: Flight altitude, speed, pitch angle, received signal strength, atmospheric temperature and humidity, and target location; The parameters are collected by the multi-sensor module on the UAV and sent to the microwave launch control center through the communication module; The control center dynamically adjusts the microwave emission direction, output power and signal frequency based on the feedback parameters.

8. A method for wireless charging of an unmanned aerial vehicle in the stratosphere according to claim 1, characterized in that, The adjustment of the signal frequency includes: The control center selects the operating frequency with the least interference from a set of preset frequencies; When it is detected that the interference value of the current frequency exceeds the threshold, switch to another frequency for transmission; The interval between each frequency switching shall not exceed 500 milliseconds.

9. A method for wireless charging of an unmanned aerial vehicle in the stratosphere according to claim 1, characterized in that, The solar auxiliary power supply comprises: Arrange solar panels with a photoelectric conversion efficiency of not less than 18% on the surface of the drone; The control module detects the solar voltage value and gives priority to solar power supply when it is higher than the set threshold; When the voltage is lower than the threshold, the microwave energy receiving module is switched to supply power.

10. A method for wireless charging of an unmanned aerial vehicle in the stratosphere according to claim 1, characterized in that, The microwave energy transmission test comprises the following steps: At no less than three flight altitudes, measure microwave transmission loss and received signal strength respectively; Evaluate the signal stability and the antenna beam focusing ability under different environmental temperature and humidity conditions and in the thin atmosphere; Adjust the parameters of the transmitting module, the structure of the receiving antenna, and the parameter configuration of the control strategy according to the test results.

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