A WPT adaptive scanning calibration radiation energy transfer method and system without prior information

Abstract

The application discloses a WPT adaptive scanning calibration radiation energy transmission method without prior information, relates to microwave wireless energy transmission directional radiation technology and phased array calibration technology, and belongs to the technical field of power generation, power transformation or power distribution. The application gradually divides an antenna from large-aperture wide-beam emission into multi-path small-aperture narrow-beam emission based on power feedback and field strength superposition principles. The method can greatly accelerate the beam convergence speed of the phased array antenna without reducing the emission effect, can calibrate and compensate phase errors in the antenna production and processing process, correct emission angle deviation, so that the T component meeting the function can be used almost without calibration, and can adaptively radiate maximum microwave power to the energy receiving target in various complex environments such as near field and far field, and has the advantages of quickly positioning the energy receiving target, power calibration focusing and directional radiation energy transmission without prior position information and energy storage components.

Description

Technical Field

[0001] This invention discloses a WPT adaptive scanning calibration radiation energy transfer method and system without prior information, which relates to microwave wireless energy transfer directional radiation technology and phased array calibration technology, and belongs to the technical field of power generation, power transformation or power distribution. Background Technology

[0002] Microwave power transmission (MTP) has attracted widespread attention in the Internet of Things (IoT) field due to its long transmission distance, high environmental adaptability, and ability to precisely transmit energy to flexible locations. The structure of an MTP system is as follows: Figure 1 As shown. Traditional MPT systems, such as space-based solar power stations and airborne microwave platforms, focus on energy transmission to ultra-high-power, ultra-long-distance, one-to-one receiving targets. Phased array technologies such as beamforming and beam pointing can achieve highly directional and concentrated transmission of microwave energy, making it possible to transmit energy to moving targets and multiple targets. Therefore, microwave wireless power transmission systems have shown significant advantages in the application of low-power electronic devices, such as applying MPT systems to smart homes, distributed sensor networks, and power supply in remote areas such as isolated islands.

[0003] In phased array power transmission systems, the transmitting end typically uses a phased array antenna array to transmit radio frequency power signals in multiple variable directions in free space using beamforming and beam-directing technologies. If the position of the receiving antenna relative to the transmitting antenna is known, the transmission angle can be obtained through mathematical calculations related to the phased array. However, even if the relative positions of the transmitting and receiving ends can be accurately measured beforehand, and the transmission angle is set, in actual operation, due to manufacturing errors in the antenna array, the theoretically calculated transmission angle cannot perfectly match the actual transmission angle. When the number of array elements is large, the main lobe is extremely thin, and the distance is far, the deviation in the transmission angle will cause the main lobe to completely deviate from the receiving end position, ultimately leading to directional transmission failure. This necessitates that the phased array antenna possess accurate beam-directing capability. Various testing and calibration techniques for phased array antennas have been proposed to address this problem. Pre-calibration techniques offer very high accuracy and good calibration results, but calibration and testing are very complex, time-consuming, and costly. In-use calibration methods often require complex testing algorithms and additional equipment expenditures.

[0004] Furthermore, traditional microwave wireless power transfer systems employ a backtracking transmission scheme that uses a guiding beam to direct the transmitting beam towards the target at the receiving end. This requires transmitting and receiving antennas at both the transmitting and receiving ends, as well as T and R components at both ends. It also necessitates high-performance FPGA components to process and store the data generated during the beam pointing and guiding process. This approach suffers from drawbacks such as requiring accurate knowledge of the target's location, complex system structure, high power consumption, and high cost. However, multi-sensor scenarios in the Internet of Things (IoT) are characterized by a large number of target sensors, low operating power levels, and few or no energy storage devices. Traditional backtracking transmission schemes are unusable in multi-sensor IoT scenarios, necessitating a simple and easy-to-use method for discovering, waking up, focusing on, and wirelessly powering target sensors in unknown locations.

[0005] In general, the ability to adaptively and rapidly calibrate phased array antennas in complex environments is the foundation and core of achieving high-efficiency microwave wireless power transfer technology, and is of great significance to the entire MPT system. This application aims to propose a WPT adaptive scanning calibration radiation algorithm without prior information to overcome the shortcomings of existing phased array microwave wireless power transfer systems. Summary of the Invention

[0006] To overcome the shortcomings of the aforementioned background technology, this invention proposes a WPT adaptive scanning calibration radiated energy transfer method and system without prior information. The method involves sequentially splitting and scanning the phased array antenna elements to rapidly converge and focus the radiated energy at the maximum power point. Based on the principles of power feedback and field strength superposition, wireless communication is used to replace the traditional backtracking scheme, enabling the discovery, awakening, focusing, and wireless energy transfer of energy-receiving targets without prior location information. This solves the technical problems of complex calibration, poor beam directionality, complex closed-loop system structure, and extremely high cost associated with traditional phased array antennas.

[0007] To achieve the above-mentioned objectives, the present invention proposes the following technical solution:

[0008] To achieve directional radiation without prior location information, the feedback path from the receiver needs to be simplified. Using an ultra-low-power wireless communication module allows the transmitter's phased array antenna to scan the entire space with a large beam, making it easier to detect and wake up the receiver module. Once awakened, the receiver automatically connects to the transmitter's access point (AP) and reports power and other information, establishing a simple closed-loop connection to detect and wake up targets without prior location information.

[0009] To achieve directional radiation, a phased array antenna splitting and calibration algorithm is proposed. The algorithm defines an uncalibrated antenna element in the transmitting phased array as a single virtual transmitting element. This virtual transmitting element is then split into several sub-virtual transmitting elements according to a preset element partitioning method. After phase scanning of each sub-virtual transmitting element, the phase shift angle of each sub-virtual transmitting element is adjusted until the transmitting phased array in the current split state delivers maximum power to the target. This process of splitting, scanning, and calibrating the sub-virtual transmitting elements continues according to the preset element partitioning method. After multiple splitting and scanning calibrations of the antenna elements, the receiver energy can reach its optimal level. Optimal receiver power should satisfy one of the following two conditions: a. The transmitter phased array antenna array is divided to the minimum number of actual elements, i.e., the number of virtual transmitter elements is equal to the number of actual independent elements in the antenna array; b. The power increase after this division is less than a certain set value. At this moment, the phase of each virtual transmitter element has reached the optimal phase, and the phase error of the actual elements in the transmitter phased array antenna array has little impact on the overall transmission power. Even if the separation operation continues, it cannot significantly improve the transmitter power, and the splitting process can be terminated early. These two conditions indicate that the splitting algorithm involved in this invention can terminate the splitting operation under the limitation of the number of actual elements in the antenna array or under the condition of achieving optimal power transmission at the transmitter. It quickly converges the process of the transmitter phased array antenna array radiating large-aperture wide-beam electromagnetic waves to the transmitter phased array antenna array radiating small-aperture narrow-beam electromagnetic waves, achieving the purpose of power calibration and focusing, and providing a phase shifting scheme for the subsequently generated directional radiation power transmission command.

[0010] To achieve rapid adjustment of the phase shift angle of a single sub-virtual array element, a perturbation-observation method is used during the adjustment process. First, the initial value of a sub-virtual array element is set to one, and its total transmitted power is read. The overall phase shift angle of the sub-virtual array element is increased or decreased in a fixed direction. If the total power fed back from the target increases, the adjustment continues in that direction; conversely, if the power fed back from the target decreases, the phase shift angle is adjusted in the opposite direction. When more than three direction changes are detected, the previously adjusted phase shift angle becomes the optimal power transmission angle for the sub-virtual array element.

[0011] The present invention, by adopting the above technical solution, has the following beneficial effects:

[0012] (1) In view of the shortcomings of existing directional radiation energy transfer schemes, such as complex system structure, complex closed-loop logic and extremely high component cost, this invention proposes an energy transfer method that can detect, wake up, focus and wirelessly transfer energy without prior location information based on the power feedback and field strength superposition principle. Through split array elements, power scanning and phase calibration operations, the phase shift angle of each array element of the phased array antenna at the transmitting end is calibrated to the angle at which the transmitting antenna array achieves the optimal transmission power without knowing the location of the energy receiving target. It can correct the initial phase error caused by the design and manufacturing of the phased array antenna. Compared with existing antenna testing and calibration technology, it has the technical advantage of efficiently realizing microwave energy directional radiation without complex calibration.

[0013] (2) Since the WPT adaptive scanning calibration radiation algorithm used in this invention does not require accurate positioning of the energy-receiving target, the receiving antenna and R component of the transmitter are eliminated, the transmitting antenna and T component of the receiver are eliminated, and the FPGA component for processing and storing the data generated in traditional backtracking and position coordinate information schemes is eliminated. Only a low-performance embedded chip is needed to realize closed-loop power regulation, which greatly simplifies the closed-loop process of the system. The low-power feedback loop allows the receiver to be used for a long time or intermittently woke up according to predetermined requirements without prior position information and without energy storage components. It can not only realize the rapid positioning of the energy transmission target, but also greatly optimize the practicality of microwave wireless energy transmission system in environmental monitoring, Internet of Things sensing and other multi-intermittent working sensor occasions. It has the technical advantages of small size, high flexibility and easy operation.

[0014] (3) The split calibration algorithm proposed in this invention can discover unknown targets and converge quickly in the subsequent calibration process. It can quickly find the phase configuration scheme for maximum power transmission to the target and realize the tracking and power transmission of the target. The split algorithm realizes the automatic scanning calibration and directional radiation process. Without human intervention and additional calculation, the transmitter can automatically discover and wake up the target, and power calibration and focusing can be performed. It can adaptively realize the optimal power transmission of the target. It is suitable for radiation environments with complex reflections such as narrow channels. It lays the foundation for the realization of high-power microwave wireless power transmission, multi-target scanning, tracking and other applications in the future. Attached Figure Description

[0015] Figure 1 This is a structural diagram of the MPT system.

[0016] Figure 2 This is a hardware block diagram of the WPT adaptive scanning calibration radiation algorithm without prior information proposed in this invention.

[0017] Figure 3 This is a flowchart of the WPT adaptive scanning calibration radiation algorithm without prior information proposed in this invention.

[0018] Figure 4 This is a schematic diagram of the antenna splitting process proposed in this invention.

[0019] Figure 5 This is a schematic diagram of the workflow for the perturbation observation method for phase adjustment.

[0020] Figure 6 This is a comparison chart of the convergence speed of the algorithm proposed in this invention. Detailed Implementation

[0021] The technical solution of the invention will now be described in detail with reference to the accompanying drawings.

[0022] The split-calibration directional transmission method proposed in this invention is inspired by active scanning. Based on the principles of power feedback and field strength superposition, it gradually splits the antenna from a large-aperture wide-beam transmission into multiple small-aperture narrow-beam transmissions. Using this method, the beam convergence speed of phased array antennas (especially phased array antennas with a large number of array elements) can be significantly accelerated without reducing the transmission effect. At the same time, it can calibrate and compensate for phase errors in the antenna manufacturing process and correct the transmission angle offset, so that the functional T-components can be used with almost no calibration, and can adaptively maximize microwave power radiation to the receiving target in various complex environments such as near and far fields.

[0023] The hardware block diagram of the WPT adaptive scanning calibration radiation algorithm without prior information proposed in this invention is as follows: Figure 2 As shown, it includes a transmitter and a receiver. The transmitter includes: an RF power source, a power divider module, K T modules, and K transmit antenna elements TX1, TX2...TX K The transmitter consists of a phased array antenna array and a main control unit. The receiver includes a receiving antenna array Rx and a target device, which includes an RF rectifier, a DC filter, a load, and a sampling communication module.

[0024] The WPT adaptive scanning calibration radiative energy transfer method proposed in this invention without prior information includes the following three stages:

[0025] In the first stage, the elements of the transmitting phased array antenna array are initially divided to enable the transmitting phased array antenna array to perform wide-beam scanning of free space. When the power information fed back by the target is received, the target is detected. When the DC power received by the receiving antenna array is sufficient to wake up the receiving communication equipment, the receiving wireless communication equipment connects to the transmitting AP to wake up the target. The smallest virtual transmitting elements after division are phase-shifted to make the transmitting phased array antenna array work at the maximum power transmission point.

[0026] In the second stage, the smallest virtual antenna array elements after the first stage are finely divided and phase-shifted to obtain a fine phase-shifting scheme that maximizes the power of the small-aperture narrow-beam transmission of the phased array antenna at the transmitting end, thereby achieving power calibration and focusing.

[0027] In the third stage, the phased array antenna array at the transmitting end radiates electromagnetic wave beams toward the target according to the phase shifting scheme determined in the second stage, thereby achieving wireless power supply.

[0028] The splitting algorithm involved in the first and second stages of array element partitioning and phase shifting can be operated according to the following process, as follows: Figure 3 As shown:

[0029] 1) Large-area scanning: Each element of the transmitting phased array antenna array with N independent elements is sequentially numbered as a1, a2, ..., a N Their phases correspond to θ1, θ2, ..., θ N =0, assuming each element is an ideal element with no phase error. These antenna elements are divided into a few k regions A1, ..., A2. k The radio frequency signals output by the transmitting modules that provide radio frequency signals to each region are of equal amplitude and phase, which makes region A i (i=1, ……, k) represents a larger-aperture virtual transmitting element, and the regions are independent of each other. The phased array antenna array at the transmitting end forms a wide beam scan of the target. Due to limitations in manufacturing processes and chips, each element has initial phase errors and differences between the near and far fields of the antenna. Even if the wide beam radiates to the expected target location, the receiving antenna array will not receive maximum power. Therefore, it is necessary to perform phase shift adjustment on each virtual transmitting element after division. The phase angle of each region is adjusted sequentially using the perturbation observation method. Each phase adjustment will adjust all transmitting modules. Since the beam angle is very wide at this time, the energy is not concentrated, making it easier to search and point to the target over a large area. The initial search will be within the 0-360° phase range (i.e., Phase shift width θ w =360°), using perturbation observation to obtain the phase shift angles θ1, ……,θ1 for maximum power transfer. N This completes one split. The perturbation-observation method described here can be summarized as follows, with its workflow diagram as follows: Figure 5 As shown: Determine a transmission phase, measure the power received by the target, and rotate the phases of all virtual transmission array elements along polar coordinates in a fixed direction (clockwise or counterclockwise). If the power received by the target increases, continue rotating; if the power received by the target decreases, rotate in the opposite direction. When the rotation direction is changed three times, the phase angle before the last change of rotation direction is the phase shift angle for maximum power transmission.

[0030] 2) Splitting Refinement: When a higher received power is obtained, the transmitting phased array antenna array in the current partition state is split. The splitting process is as follows: Figure 4 As shown, each region is further divided into k smaller regions A1, A2, ..., A k 2 In this process, the initial phase value of each region inherits the value from the previous split. The phase difference between each virtual transmitting element is equal and adjustable. The subsequent split increases the number of independent virtual transmitting elements. According to the phased array principle, the beamwidth of the electromagnetic wave radiated by the phased array antenna at the transmitting end becomes narrower, and the energy is more concentrated. Next, based on the principle of field strength superposition, the phase of each independent virtual transmitting element is adjusted to superimpose the field strength in a fixed direction, thereby further optimizing the transmission power. Since each region achieved a relatively optimal phase shift angle in the previous optimization process, this time it is only necessary to search within a smaller range, defining the search center. Search width The range of θ that can be searched is then allowed. It is particularly important to note that if the best result θ obtained from the search is... max On boundary conditions ( If the search area is not found to be accurate, it indicates poor phase accuracy in that region, necessitating a wider search. Based on the fundamental principle of phased array field superposition, such situations are unlikely to occur on a large scale. The overall search will be completed more quickly within a smaller angular range.

[0031] 3) Termination of optimization: Repeat the above steps. In the (n+1)th round, divide, scan, and optimize the antenna from the previous round until P is reached. max The change is less than a certain set value Or the antenna region has been divided into the smallest physical array elements ( If the condition is met, the splitting will terminate. At this point, the condition for transferring maximum power to the receiving target has been found. Record the control values ​​θ1, ..., θ2 of each array element at this time. N This will be reserved for future power transmission.

[0032] The convergence performance analysis of the proposed algorithm is as follows. Analyzing the entire process, the splitting speed of this algorithm is exponential; therefore, the initial number of blocks k does not need to be very large to achieve optimal transmission efficiency after a few n rounds of splitting. For a phased array antenna with N elements, the expected number of phase shifts required for the first search can be denoted as... Where p is the number of phase shifts required to find the optimal efficiency point for each array element region, and s is the phase shift step size. In each subsequent search, the number of search regions increases by a factor of k, while the required phase shift angle range θ... w If the number of phase shifts is reduced by a factor of k, the expected number of phase shifts in each search round is: It remains close to P1. The final total number of searches for this algorithm is... The field strength superposition algorithm, which does not use this algorithm, requires an independent full-range search for each antenna element, and the number of searches is... According to the termination conditions Then there should be Clearly, our proposed algorithm significantly reduces the number of phase shifts, and its convergence speed to the optimal power point is significantly better than other methods. Figure 6 The results show that even when k=2, the proposed algorithm is still superior to the field strength superposition algorithm. When the number of antenna elements N is 100, the convergence speed is 7.5 times faster than the traditional field strength superposition algorithm, and when N is 300, the convergence speed is more than 18 times faster.

[0033] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A WPT adaptive scanning calibration radiative energy transfer method without prior information, characterized in that, The transmitting phased array antenna array is divided according to a predetermined element division method to enable the transmitting phased array antenna elements to radiate large-aperture, wide-beam electromagnetic waves into free space. Based on the DC power signal and target power information received by the receiving antenna array from the receiving end, the target is detected and activated. Phase shifting is performed on all the divided sub-virtual transmitting elements until the target power information reaches its maximum value. This process of dividing the smallest unit of virtual transmitting elements and adjusting the phase shift angle based on the power scan results is repeated to obtain the phase shifting scheme when the transmitting phased array antenna array transmits the small-aperture, narrow-beam electromagnetic waves radiated into free space to the target with maximum power. This phase shifting scheme consists of the phase shift angles of all the smallest units of virtual transmitting elements in the final division. A directional radiation power transfer command is generated based on this phase shifting scheme. The predetermined array element partitioning method is as follows: the transmitting phased array antenna array is divided into k sub-virtual transmitting array elements, and each sub-virtual transmitting array element is further divided into k sub-elements to obtain k 2 The smallest virtual transmission array element is divided into n parts, and so on, until k is obtained after n divisions. n The smallest unit of the virtual transmission array element; During the repeated process of dividing the smallest virtual transmitter array element and adjusting the phase shift angle according to the power scan results, after the current division operation of the smallest virtual transmitter array element is performed, with... As a search center, in The phase shift angle of the virtual transmission array element, which is the smallest unit obtained by the current partitioning operation, is searched in the middle. Let N be the search center for the phase shift angle of the virtual transmit element of the i-th smallest unit obtained from the current partitioning operation, where N is the actual number of elements in the transmitter phased array antenna array, and n is the number of partitioning operations. For search width, k is the initial number of blocks.

2. The WPT adaptive scanning calibration radiation energy transfer method without prior information as described in claim 1, characterized in that, The specific method for detecting and waking up a target based on the DC power signal and target power information received by the receiving antenna array from the receiving end is as follows: When the target power information is received from the receiving end, the transmitting end detects the target; when the DC power signal received by the receiving antenna array from the receiving end is sufficient to wake up the receiving end communication device, the wireless communication device connects to the transmitting end AP, and the transmitting end wakes up the target.

3. The WPT adaptive scanning calibration radiation energy transfer method without prior information as described in claim 1, characterized in that, The specific method for adjusting the phase of all sub-virtual transmitter elements after division until the target power information reaches the maximum value is as follows: After determining the transmission phase, measure the target power information fed back by the receiver, rotate the phase of all sub-virtual transmitter elements along the polar coordinates in the direction of increasing the target power, and after changing the rotation direction three times, take the phase angle before the last change of rotation direction as the phase shift angle of all sub-virtual transmitter elements.

4. The WPT adaptive scanning calibration radiation energy transfer method without prior information as described in claim 1, characterized in that, The stopping condition for the operation of dividing the smallest unit of virtual transmission array elements and adjusting the phase shift angle according to the power scan results is: the number of the smallest unit of virtual transmission array elements obtained under the current division operation is equal to the number of actual array elements of the phased array antenna array at the transmitting end, or the increment of the target power information received after the current division operation compared with the target power information received after the previous division operation is less than a set value.

5. A WPT system for implementing the adaptive scanning calibration radiation energy transfer method of claim 1, characterized in that, include: RF power source, outputting a reference RF power signal to the power divider module; The power divider module outputs K power signals with equal phase and amplitude. K T modules, each T module receives one power signal output from the power divider module, receives the directional radiation power transfer command output from the main control unit, parses the directional radiation power transfer command to obtain the amplitude and phase adjustment information of the transmit beam, modulates the received power signal according to the amplitude and phase adjustment information of the transmit beam, and sends the modulated power signal to a transmit antenna element. A phased array antenna array consisting of K transmitting antenna elements converts the power signal received by each transmitting antenna element into an electromagnetic wave beam and radiates it into free space at a specified location. The receiving antenna array collects the electromagnetic wave beam radiated by the transmitting phased array antenna array and outputs the induced sinusoidal power signal with the same frequency as the reference radio frequency power signal to the target. and, The main control module collects the DC power signal received by the receiving antenna array, the DC output voltage information of each target at the receiving end, and the load current information. It calculates the power information of each target at the receiving end and divides the transmitting phased array antenna array according to a predetermined array element division method so that the transmitting phased array antenna elements radiate large-aperture wide-beam electromagnetic waves in free space. Based on the DC power signal received by the receiving antenna array and the target power information fed back by the receiving end, it detects and wakes up the target. It performs phase shift adjustment on all the divided sub-virtual transmitting array elements until the target power information reaches the maximum value. It repeats the operation of dividing the smallest unit of virtual transmitting array elements and adjusting the phase shift angle according to the power scan results to obtain the phase shift scheme when the transmitting phased array antenna array transmits small-aperture narrow-beam electromagnetic waves radiated in free space to the target with maximum power. The phase shift scheme is the phase shift angle of all the smallest units of virtual transmitting array elements in the last division. It outputs the directional radiation power transfer command containing the phase shift scheme to K T modules.

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