Electric power transmission device, control method, and control program

Abstract

To adequately radiate a radio wave from an electric power transmission device when there are a plurality of irradiation avoidance objects.SOLUTION: An electric power transmission device 10 comprises: a transmission / reception part 13; and a weight generation part 17 which controls the directivity of an antenna for transmitting a transmission signal, based upon a reception signal and information related to an object different from an electric power reception device, so that the radio wave transmitting the transmission signal has an intensity less than a predetermined intensity. The weight generation part 17 is configured to: calculate a gram matrix from a matrix composed of array response vectors based upon a prescribed signal transmitted from the electric power reception device, the number of a plurality of null points for an object, and directions of the null points; find a unitary matrix, a rank, and a plurality of characteristic values through characteristic value decomposition of the gram matrix; lower the rank based upon a first characteristic value meeting predetermined conditions among the plurality of characteristic values; and use the rank and unitary matrix to generate a transmission weight of an antenna for transmitting the transmission signal to the power reception device.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present application relates to a power transmitting device, a control method, and a control program. [Background technology]

[0002] In wireless power supply using an array antenna, a retrodirective method is sometimes used. In the retrodirective method, a pilot signal is transmitted from a power receiving device prior to power transmission, and the power transmitting device estimates the radio wave propagation channel characteristics of the pilot signal and generates a transmission weight based on the estimation, thereby controlling the antenna directivity. Patent Document 1 discloses a wireless power supply device that calculates a propagation coefficient between multiple antenna elements and an antenna of a device to be powered, and adjusts the phase and amplitude of a power supply signal for each of the multiple antenna elements based on the propagation coefficient.

[0003] Cited Document 2 discloses a technology for supplying power to wireless devices such as actuators that require large power by an open-space wireless power distribution method while complying with the radio wave protection guidelines. Cited Document 3 discloses a leakage electromagnetic wave control system that prevents people from entering the range of leakage electromagnetic waves in a space where people are present. Cited Document 4 discloses a wireless power supply device that weakens the strength of radio waves reaching the position of an object without stopping power supply by radio waves to the object when the object is within a predetermined range. In addition, Non-Patent Document 1 describes the effectiveness in a multipath environment where reflected waves exist and an out-of-line-of-sight environment where a shield exists. In this document, the method is called a multipath retrodirective method. And, a technology is described in which a pilot signal propagating from a power receiving device to a power transmitting device does not pass through the human body even when a person is present in the usage environment, so that the pilot signal is not radiated from the power transmitting device to the human body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-010485 A [Patent Document 2] JP 2010-233430 A [Patent Document 3] JP 2014-217093 A [Patent Document 4] JP 2020-005468 A [Non-patent literature]

[0005] [Non-Patent Document 1] Taichi Sasaki, Naoki Shinohara, “Study on Multipath Retrodirective for Efficient and Safe Indoor Microwave Power Transmission,” 2019 IEEE Wireless Power Transfer Conference(WPTC), 2019 Summary of the Invention [Problem to be solved by the invention]

[0006] In wireless transmission systems in indoor manned environments, the challenge is to improve the transmission efficiency of received power while ensuring human safety. One solution to this problem is the multi-point null-constrained retrodirective method that uses an array antenna on the power transmitter side. Conventional power transmitters that use the multi-point null-constrained retrodirective method have room for improvement in terms of appropriate radiation of radio waves from the power transmitter when there are multiple targets to avoid irradiation. [Means for solving the problem]

[0007] A power transmitting device according to one aspect includes a transceiver unit that transmits a transmission signal to a power receiving device and receives a reception signal transmitted from the power receiving device using an antenna having multiple antenna elements, and a weight generation unit that controls the directivity of the antenna that transmits the transmission signal based on the received signal and information regarding an object other than the power receiving device so that the strength of the radio waves transmitting the transmission signal to the object is below a predetermined level, wherein the weight generation unit calculates a Gram matrix from a matrix of an array response vector based on a specified signal transmitted from the power receiving device and the number of multiple null points relative to the object and the directions of the null points, obtains a unitary matrix, a rank, and multiple eigenvalues ​​by eigenvalue decomposition of the Gram matrix, reduces the rank based on a first eigenvalue among the multiple eigenvalues ​​that satisfies a predetermined condition, and generates a transmission weight for the antenna that transmits the transmission signal to the power receiving device using the rank and the unitary matrix.

[0008] A control method according to one aspect includes a transmission / reception step of transmitting a transmission signal to a power receiving device and receiving a reception signal transmitted from the power receiving device using an antenna having a plurality of antenna elements, and a weight generation step of controlling a directivity of the antenna that transmits the transmission signal based on the received signal and information regarding an object other than the power receiving device so that the strength of the radio waves transmitting the transmission signal to the object is equal to or lower than a predetermined value, wherein the weight generation step calculates a Gram matrix from a matrix obtained by matrixing an array response vector based on a specified signal transmitted from the power receiving device and the number and directions of a plurality of null points relative to the object, obtains a unitary matrix, a rank, and a plurality of eigenvalues ​​by eigenvalue decomposition of the Gram matrix, reduces the rank based on a first eigenvalue that satisfies a predetermined condition from the plurality of eigenvalues, and generates a transmission weight for the antenna that transmits the transmission signal to the power receiving device using the rank and the unitary matrix.

[0009] A control program according to one aspect causes a computer to execute a transmission / reception process for transmitting a transmission signal to a power receiving device and receiving a reception signal transmitted from the power receiving device using an antenna having multiple antenna elements, and a weight generation process for controlling the directivity of the antenna that transmits the transmission signal based on the received signal and information about an object other than the power receiving device so that the strength of the radio waves transmitting the transmission signal to the object is equal to or lower than a predetermined value. The weight generation process causes a computer to execute a process of calculating a Gram matrix from a matrix obtained by matrixing an array response vector based on a specified signal transmitted from the power receiving device and the number of multiple null points with respect to the object and the directions of the null points, determining a unitary matrix, a rank, and multiple eigenvalues ​​by eigenvalue decomposition of the Gram matrix, lowering the rank based on a first eigenvalue that satisfies a predetermined condition from the multiple eigenvalues, and generating a transmission weight for the antenna that transmits the transmission signal to the power receiving device using the rank and the unitary matrix. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram for explaining an overview of a wireless power transmission system according to an embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of the configuration of the power transmitting device according to the embodiment. [Diagram 3] FIG. 3 is a diagram showing an example of an equivalent low-pass system analysis model of an adaptive array antenna. [Figure 4] FIG. 4 is a diagram showing an example of the relationship between direction and phase in an adaptive array antenna. [Diagram 5] FIG. 5 is a diagram for explaining an example of a plurality of null points in an object region. [Figure 6] FIG. 6 is a data flow showing an example in which the weight generating unit calculates the array response vector. [Figure 7] FIG. 7 is a diagram showing an example of a data flow from performing eigenvalue decomposition on the array response vector to reducing the rank and calculating the vector a'd. [Figure 8]FIG. 8 is a diagram showing an example of a data flow from receiving directions, regions, and importance information of the entire object as object information of a plurality of objects from the detection unit to calculating an array response vector. [Figure 9] FIG. 9 is a diagram for explaining an example of step S16 in FIG. [Figure 10] FIG. 10 is a diagram showing an example of a data flow from performing eigenvalue decomposition on the array response vector and the importance to lowering the rank and calculating a'd. [Figure 11] FIG. 11 is a diagram illustrating an example of the configuration of a power receiving device according to the embodiment. [Figure 12] FIG. 12 is a diagram illustrating an example of a processing procedure of the power transmitting device in the system illustrated in FIG. [Figure 13] FIG. 13 is a diagram for explaining a data flow of the power transmitting device shown in FIG. [Figure 14] FIG. 14 is a flowchart showing a first example of determining the rank of a matrix. [Figure 15] FIG. 15 is a flowchart illustrating a second example of determining the rank of a matrix. [Figure 16] FIG. 16 is a flowchart illustrating a third example of determining the rank of a matrix. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A number of embodiments according to the present application will be described in detail with reference to the drawings. Note that the present invention is not limited to the following description. Furthermore, the components in the following description include those that a person skilled in the art can easily imagine, those that are substantially the same, and those that are within the so-called equivalent range. In the following description, similar components may be given the same reference numerals. Furthermore, duplicated descriptions may be omitted.

[0012] FIG. 1 is a diagram for explaining an outline of a wireless power transmission system according to an embodiment. The system 1 shown in FIG. 1 includes, for example, a wireless power transmission system capable of microwave transmission type (space transmission type) wireless power transmission. Wireless power transmission is a mechanism that allows power to be transmitted without using, for example, a cable or a plug. The system 1 can be applied to, for example, space solar power generation. The microwave transmission type system 1 uses radio waves (microwaves) as energy transmission. A plurality of frequency bands are available for the radio waves used in the microwave transmission type system 1, and in Japan, for example, the 920 MHz band, the 2.4 GHz band, the 5.7 GHz band, and the like are included. The microwave transmission type system 1 can use a retrodirective method. In this embodiment, the system 1 makes it possible to simultaneously improve power supply efficiency appropriate to the situation and ensure safety.

[0013] In the example shown in FIG. 1, the system 1 uses a multipath retrodirective method. The system 1 includes a power transmitting device 10 and a power receiving device 20. The system 1 transmits power from the power transmitting device 10 to the power receiving device 20 using multiple paths (propagation channels). The power transmitting device 10 is a transmission device in the system 1 that transmits power wirelessly and is a device capable of transmitting radio waves for power supply. The power transmitting device 10 includes a sensor unit 15 that can detect an object such as a human body in the vicinity of the array antenna 11. In the following description, the power transmitting device 10 may be referred to as "own device".

[0014] The power receiving device 20 is a power-supplied device that receives radio waves for power supply and obtains power in the system 1. The power receiving device 20 includes, for example, a smartphone, a tablet terminal, an IoT (Internet of Things) sensor, a notebook personal computer, a drone, an electric car, an electric bicycle, a game machine, etc. In this manner, the power receiving device 20 of the present disclosure may be a mobile device.

[0015] In scene C1, the power receiving device 20 can transmit a prescribed signal 1000 determined between the power receiving device 20 and the power transmitting device 10. The prescribed signal 1000 includes, for example, a beacon, a pilot signal, and the like. The power receiving device 20 can transmit the prescribed signal 1000, for example, at a transmission period. The power receiving device 20 can transmit the prescribed signal 1000 by emitting radio waves including the prescribed signal 1000. On the other hand, when the power transmitting device 10 receives the prescribed signal 1000, it estimates characteristic values ​​(array response vectors) of multiple paths from the power receiving device 20 to the power transmitting device 10 based on the prescribed signal 1000. The power transmitting device 10 calculates a weighting coefficient for transmission using the estimated array response vector for the power receiving device 20.

[0016] In scene C2, the power transmitting device 10 performs directivity control by multiplying each antenna by a weighting coefficient, and radiates radio waves including a transmission signal 2000 for power supply. Directivity control means, for example, controlling the relationship between the radiation direction and radiation intensity of radio waves. If the frequencies of the prescribed signal 1000 and the transmission signal 2000 are the same and time fluctuations in the propagation path are ignored, the characteristics of the multiple paths from the power transmitting device 10 to the power receiving device 20 match the characteristics from the power receiving device 20 to the power transmitting device 10. As a result, the radio waves 2000W radiated from the power transmitting device 10 have a radiation pattern that makes use of not only paths toward the power receiving device 20, but also paths toward a direction different from the power receiving device 20.

[0017] (Embodiment) [Configuration of power transmitting device according to embodiment] Fig. 2 is a diagram showing an example of a configuration of a power transmitting device 10 according to an embodiment. As shown in Fig. 2, the power transmitting device 10 includes an array antenna 11, a transmission signal generating unit 12, a transmitting / receiving unit 13, an estimating unit 14, a sensor unit 15, a detecting unit 16, a weight generating unit 17, and a multiplying unit 18.

[0018] The array antenna 11 is configured to be capable of directivity control (beam forming). The array antenna 11 includes a plurality of antenna elements 11A. For example, the array antenna 11 is configured such that each of the plurality of antenna elements 11A radiates the same radio wave, and the phase and power intensity of each element are adjusted to strengthen the radio wave in a specific direction and to weaken the radio wave by canceling each other out in another direction. The array antenna 11 radiates radio waves 2000W including a transmission signal 2000, and receives radio waves including a prescribed signal 1000 from the power receiving device 20. The array antenna 11 supplies the received signal to the transmitting / receiving unit 13. In this embodiment, for the sake of simplicity, the array antenna 11 is an example of an antenna, and a case where the array antenna 11 includes three or more antenna elements 11A will be described, but the number of antenna elements 11A is not limited thereto.

[0019] The transmission signal generating unit 12 generates a transmission signal 2000 for power supply to be transmitted to the power receiving device 20. The transmission signal 2000 is a signal for emitting radio waves 2000W capable of supplying power. For example, the transmission signal 2000 may be a baseband signal. The transmission signal 2000 may be, for example, an unmodulated signal or a modulated signal. In the case of an unmodulated signal, there is no time variation in the transmission signal 2000 during the transmission period. In the case of a modulated signal, the transmission signal generating unit 12 time-varies the transmission signal 2000 during the transmission period. The transmission signal generating unit 12 includes, for example, stopping the transmission signal 2000 at the timing of receiving the specified signal 1000. The transmission signal generating unit 12 is electrically connected to the multiplier unit 18 and supplies the generated transmission signal 2000 to the multiplier unit 18.

[0020] The transmitting / receiving unit 13 has a plurality of transmitting / receiving circuits 13A electrically connected to each of the plurality of antenna elements 11A of the array antenna 11. The transmitting / receiving circuit 13A is electrically connected to the estimating unit 14, the multiplying unit 18, and the like. The transmitting / receiving circuit 13A extracts a reception signal received by the antenna element 11A and supplies it to the estimating unit 14. The transmitting / receiving circuit 13A causes the antenna element 11A to radiate a transmission signal 2000 multiplied by a transmission weight in the multiplying unit 18. The transmission weight includes, for example, a weighting coefficient capable of adjusting the amplitude and phase. The transmitting / receiving unit 13 simultaneously radiates radio waves 2000W including the transmission signal 2000 multiplied by the transmission weight (complex amplitude) from the plurality of antenna elements 11A, so that the power transmitting device 10 radiates radio waves 2000W with controlled directivity. The transmitting / receiving unit 13 is an example of a transmitting unit and a receiving unit, and the transmitting unit and the receiving unit may be configured separately.

[0021] The estimation unit 14 estimates a propagation channel characteristic (impulse response) from a reference signal 1000 included in a received signal received by the plurality of antenna elements 11A. The propagation channel characteristic (impulse response) includes, for example, an amplitude characteristic and a phase characteristic. The array response vector indicates, for example, channel characteristics for the number of antennas. The array response vector includes, for example, a vector in which the propagation channel characteristic (impulse response) for each of the plurality of antenna elements 11A is arranged. The array response vector in the receiving process is also called a receiving response vector. The estimation unit 14 estimates the receiving response vector using a known algorithm, for example, as disclosed in Japanese Patent Application Laid-Open No. 2002-43995. The estimation unit 14 supplies vector data of the array response vector to a weight generation unit 17.

[0022] The sensor unit 15 can acquire information capable of detecting the presence / absence, direction, area, distance, importance, and the like of the object 5000 in the radio wave propagation environment of the power transmitting device 10. The radio wave propagation environment includes, for example, a space in which radio waves 2000W are propagated between the power transmitting device 10 and the power receiving device 20. The sensor unit 15 acquires information on the object 5000 present in the radio wave propagation environment using, for example, a camera, a radar such as a millimeter wave radar, a LIDAR (Laser Imaging Detection and Ranging), a ToF (Time of Flight) sensor, an infrared sensor, a human sensor, a depth sensor, and the like. The sensor unit 15 may be provided outside the power transmitting device 10. The sensor unit 15 is electrically connected to the detection unit 16, and supplies the detection unit 16 with sensor information capable of detecting the presence / absence, direction, area, distance, importance, and the like of the object 5000 in the radio wave propagation environment. The sensor information may include, for example, information on the presence / absence, direction, distance, area, position, importance, image, and the like of the object 5000.

[0023] The detection unit 16 detects information on the presence or absence, direction, area, distance, importance, etc. of an object 5000 different from the power receiving device 20 in the radio wave propagation environment based on the sensor information from the sensor unit 15. The object 5000 includes, for example, a human being, an animal, a robot, a moving object, a plant, food, and a device that transmits or receives electromagnetic waves. The detection unit 16 executes a publicly known object recognition process on an image indicated by the sensor information, and detects information on the presence or absence, the area in which the object 5000 exists, the shape, the direction of the object 5000 from the own device, the distance from the own device to the object 5000, and an important part such as the head, etc. in the radio wave propagation environment. For example, the detection unit 16 detects the direction and area of ​​the object 5000 from the array antenna 11 based on the direction and area of ​​the object 5000 detected from the sensor information and the relative positional relationship between the sensor unit 15 and the array antenna 11. When multiple objects 5000 exist, the detection unit 16 detects the direction, area, distance, importance, etc. of each of the multiple objects 5000. The detection unit 16 is electrically connected to the weight generation unit 17, and supplies object information of the object 5000 from the array antenna 11 to the weight generation unit 17. The object information may include, for example, information that can identify the number of objects 5000 different from the power receiving device 20 in the radio wave propagation environment, the direction of the object 5000 from the array antenna 11, the area, the distance from the array antenna 11 to the object 5000, and the like. Importance may be given to the direction and area of ​​the object 5000. Note that the information on the area can be information that can identify the size of the object 5000 according to the arrangement of the multiple antenna elements 11A. For example, the area of ​​the object 5000 in the case where the multiple antenna elements 11A are arranged in a matrix can be set to have vertical and horizontal angular spreads, as in the area 151. The area 151 of the object 5000 may be a spatial area according to the outer shape of the object 5000, and the like. For example, the area of ​​the object 5000 in the case where a plurality of antenna elements 11A are arranged side by side in the horizontal direction can be set to have a horizontal angular spread, etc., like the area 151. In this manner, the detection unit 16 of the present disclosure detects information on the number, direction, area, distance, importance, etc. of the object 5000 different from the power receiving device 20 in the radio wave propagation environment based on the sensor information from the sensor unit 15, and supplies the information to the weight generation unit 17 as object information.

[0024] The sensor information includes, for example, information indicating the presence or absence, direction, area, position, importance, etc. of the object 5000 from the array antenna 11. The sensor information includes, for example, identifiable information such as an area 151 including the object 5000 and a size 152, as shown in FIG. 2. The sensor information can be information that identifies the size of the object 5000 set according to the arrangement of the multiple antenna elements 11A. For example, when the multiple antenna elements 11A are arranged in a matrix, the area 151 of the object 5000 can set the length and width, the position, the shape of the object 5000, etc. For example, when the multiple antenna elements 11A are arranged in one direction, the size 152 of the object 5000 can set the length and distance in one direction such as width and height, the angle range from the own aircraft, etc. The area 151 of the object 5000 may be a spatial area according to the outer shape of the object 5000, etc.

[0025] The weight generating unit 17 generates weights for power transmission based on the array response vector for the power receiving device 20, which is the estimation result of the estimating unit 14, and object information of the object 5000 different from the power receiving device 20, which is the detection result of the detecting unit 16. For example, a ZF (Zero-Forcing) algorithm or an MMSE (Minimum Mean Square Error) algorithm used in MIMO can be used as a method for generating the weights. The weight generating unit 17 is electrically connected to the multiplying unit 18, and supplies weight information indicating the weights for power transmission to the multiplying unit 18. The weight generating unit 17 includes a storage unit 17D, and stores various information such as a control program and data required for weight generation in the storage unit 17D.

[0026] The storage unit 17D may include any non-transient storage medium such as a semiconductor storage medium and a magnetic storage medium. The storage unit 17D may include a combination of a storage medium such as a memory card, an optical disk, or a magneto-optical disk, and a storage medium reader. The storage unit 17D may include a storage device used as a temporary storage area such as a RAM. The storage unit 17D may be provided outside the weight generation unit 17.

[0027] The storage unit 17D may store various programs that cause the entire power transmission device 10 or the weight generation unit 17 to function, and various information used by the entire power transmission device 10 or the weight generation unit 17. In addition, the implementation form of the program is not limited to application programs such as object code compiled by a compiler and program code executed by an interpreter, and may be in the form of a program module incorporated into an operating system. Furthermore, the program may or may not be configured so that all processing is performed only by the CPU on the control board. The program used in the present disclosure may be configured so that a part or all of it is executed by another processing unit implemented on an expansion board or expansion unit added to the board as necessary.

[0028] The multiplier 18 multiplies the transmission signal 2000 from the transmission signal generator 12 by a weight for each of the antenna elements 11A based on the weight information from the weight generator 17. The multiplier 18 has, for example, a multiplier. The multiplier 18 supplies the transmission signal 2000 multiplied by the weight corresponding to the antenna element 11A to the transmission / reception circuit 13A corresponding to the antenna element 11A.

[0029] At least one of the transmission signal generating unit 12, the transceiver unit 13, the estimation unit 14, the sensor unit 15, the detection unit 16, the weight generating unit 17, the multiplication unit 18, and the like that constitute the power transmitting device 10 may be realized by one or more processors and memories. The processor may include a general-purpose processor that executes a specific function by loading a specific program, and a dedicated processor specialized for a specific process. The dedicated processor may include an application-specific IC such as an ASIC (Application Specific Integrated Circuit). The processor may include a programmable logic device (PLD), for example. The PLD may include a field-programmable gate array (FPGA). At least one of the transmission signal generating unit 12, the transceiver unit 13, the estimation unit 14, the sensor unit 15, the detection unit 16, the weight generating unit 17, the multiplication unit 18, and the like that constitute the power transmitting device 10 may be realized by either a system-on-a-chip (SoC) in which one or more processors work together, or a system in a package (SiP). At least one of the components constituting the power transmission device 10, such as the transmission signal generating unit 12, the transceiver unit 13, the estimation unit 14, the sensor unit 15, the detection unit 16, the weight generating unit 17, and the multiplication unit 18, may control the operation of each component of the power transmission device 10.

[0030] An example of the functional configuration of the power transmitting device 10 according to the present embodiment has been described above. Note that the above configuration described with reference to Fig. 2 is merely an example, and the functional configuration of the power transmitting device 10 according to the present embodiment is not limited to this example. The functional configuration of the power transmitting device 10 according to the present embodiment can be flexibly modified according to the specifications and operation.

[0031] [Weight generation method of power transmission device according to embodiment and problems] The weight generation method and the problems will be described below. Fig. 3 is a diagram showing an example of an equivalent low-pass system analysis model of an adaptive array antenna. Fig. 4 is a diagram showing an example of the relationship between direction and phase in an adaptive array antenna. For the sake of simplicity, a case will be described in which a plurality of antenna elements 11A of the array antenna 11 are arranged at equal intervals in the horizontal direction. The weight generation methods will be described in the order of the retrodirective method that does not form a null, the retrodirective method with linear constraint that forms a null, and the retrodirective method with multi-point null constraint that supports widening of the null angle, and finally the problems of the retrodirective method with multi-point null constraint will be described.

[0032] As shown in FIG. 3, the adaptive array antenna transmits a complex amplitude w k Complex conjugate w of (weight) k * After multiplying by, radio waves of 2000 W are emitted simultaneously from K antenna elements 11A. * When a character has an asterisk (*) on its right side, it means the complex conjugate. Weight w k where k=0, ,K-1. At the receiving point 200P, a composite signal of 2000W of radio waves radiated from K antenna elements 11A is observed. At this time, the amplitude and phase change for each propagation channel. Therefore, the impulse response of the propagation channel between the antenna elements 11A #0 to #K-1 and the receiving point 200P is expressed as Z k (complex number), the analytical array antenna characteristics are given by the following (Equation 1).

number

[0033] In this disclosure, the analytical array antenna characteristic is referred to as the array response value AR. If the weight vector is w and the array response vector is a, then (Equation 1) can be expressed as the inner product of complex vectors in the following (Equation 2). Note that in this disclosure, (·) H When an "H" is written on the right side of a letter, it means complex conjugate transpose (Hermitian transpose).

number

[0034] When the weight vector w and the array response vector a are expressed by concrete elements, they are given by the following (Equation 3).

number

[0035] If the array response vector a is known, then the array response value AR at the receiving point 200P can be controlled by providing an appropriate weight vector w. When determining the weight vector w, it is necessary to ensure that the square of the norm of the weight vector w is 1 (||w|| 2 =1).

[0036] In the retrodirective system 1, an array response vector a is calculated based on a prescribed signal 1000 (pilot signal) transmitted from the power receiving device 20. d and use this to find the optimal weight vector w opt If we ignore the time variation of the propagation channel, the array response vector a d can be regarded as an array response vector from the power transmitting device 10 to the power receiving device 20. However, the pilot signal has the same frequency as the radio wave used during power transmission. ||w|| 2 = 1, the magnitude of the array response value |w H a d The optimal weight vector w that maximizes | opt can be expressed as the following (Equation 4).

number

[0037] As described above, the optimal weight vector w for retrodirective transmission is opt is the array response vector of the received pilot signal a dThis is sufficient, and information such as the direction of the receiving point 200P is unnecessary. However, in the retro-directive method, radiation to an object 5000 different from the power receiving device 20 in the radio wave propagation environment is not considered.

[0038] Next, the simultaneous realization of the retro-directive method and multiple (for example, M) null formations will be described. Thereby, the power transmission device 10 can suppress radiation to an object 5000 different from the power receiving device 20 in the radio wave propagation environment. In the present disclosure, this is referred to as a retro-directive method with linear constraints.

[0039] A null means that the gain such as the direction or point becomes zero in the directivity of the array antenna 11. To form a null with the array antenna 11, for the array response vector a i (i = 1, ···, M), the magnitude |w H a i | may be set to zero. Under this condition, the magnitude |w d of the array response value of the array response vector a H a d | is maximized. This can be formulated as an optimization problem shown in the following (Equation 5). Here, K is the number of antenna elements 11A. M is the number of nulls. Since the degree of freedom is K - 1, M < K is set. argmax (argument of the maximum) means the set of values that achieve the maximum value. (Equation 5) is an equation for obtaining the optimal weight vector w H a d such that |w opt | is maximized.

Equation

[0040] The optimization problem of (Equation 5) has a closed-form solution. When a’ d is defined as shown in the following (Equation 6), the optimal weight vector w opt is given by the following (Equation 7).

Equation

[0041] Here, A is the array response vector a1, a2, ···, a which is an array of M complex column vectors M arranged as the matrix shown in the following (Equation 8). [Mathematics]

[0042] Also, A + is the Moore - Penrose generalized inverse matrix of A. And A + satisfies AA + A = A, A + AA + = A + , (AA + ) H = AA + , (A + A) H = A + A. When the array response vectors a1, a2, ···, a which are complex column vectors are linearly independent, A M = (A + A) H A -1 A H .

[0043] For the weight vector w corresponding to the null array response value, w H a i = 0 (i = 1, ···, M < K) must be satisfied. Therefore, considering these as a system of homogeneous linear equations, it can be expressed as the product of a matrix and a vector using the matrix A formed by arranging the M complex column vectors a1, a2, ···, a as A M w = 0. The general solution is given by using the Moore - Penrose generalized inverse matrix A H as w = (I - AA + ) + z = (I - AA H )z, where z is an arbitrary complex vector. The magnitude of the array response value to be maximized |w​​H a d |to w=(I-AA + ) H z=(I-AA + )z is substituted, |w H a d |=|z H (I-AA + )a d | is obtained. And, by the Cauchy-Schwarz inequality, |w H a d |=|z H (I-AA + )a d |≦||z||·||(I-AA + )a d || holds true. |w H a d | is maximized when the inequality is equal, and then z=γ(I-AA + )a d where γ is a complex constant.

[0044] The optimal weight vector w opt is the above-mentioned w=(I-AA + ) H z=(I-AA + )z, z=γ(I-AA + )a d By substituting, w opt =γ(I-AA + )a d Here, a' is given as in (Eq. 6). d =(I-AA + )a d Then, ||w opt || 2 = |γ| 2 ||a' d || 2 = 1, γ = 1 / ||a' d Therefore, the optimal weight vector w opt can be expressed as the above-mentioned (Equation 7).

[0045] Next, an example of a method for calculating an array response vector corresponding to a null will be described. The array response vector between the power transmitting device 10 and the power receiving device 20 can be estimated from the specified signal 1000. However, if it is assumed that the specified signal 1000 is not transmitted from the target to which the null is to be directed, it is necessary to calculate the array response vector by another method. In the present disclosure, the purpose is to suppress radio waves traveling directly from the power transmitting device 10 to the target to which the null is to be directed, and the array response vector is calculated from object information of the object 5000, which is the null target, acquired using the sensor unit 15 and the detection unit 16.

[0046] As shown in Fig. 4, in a linear array in which K antenna elements 11A are arranged at equal intervals, the array response vector a in the far field radiated in a direction rotated clockwise by θ (-π / 2<θ<π / 2) from the broadside is given by the following (Equation 9). The broadside is a direction perpendicular to the direction in which the antenna elements 11A are arranged, and is the upward direction in Fig. 4. The inter-element distance from antenna element 11A #0 to antenna element 11A #k of reference point 200B is kd, and the inter-element distance from antenna element 11A #0 to antenna element 11A #K-1 of reference point 200B is (K-1)d.

number

[0047] Here, the impulse response Z is expressed by the following (Equation 10). j is the imaginary unit, and j 2 =-1, and λ is the wavelength.

number

[0048] By this, if the direction θ of the null target is known, M array response vectors a i (i=1, 2, , M) can be calculated as shown in (Equation 11) below. Note that the M directions θ are θ=θ i (i=1,2,...,M) and the impulse response Z i is the direction θ ican be obtained from the following (Equation 12).

number

number

[0049] The power transmitting device 10 can suppress radiation to an object 5000 different from the power receiving device 20 in a radio wave propagation environment by using a linearly constrained retrodirective method, but the object 5000 that is the null target has a size, and it is desirable to widen the null angle according to the area of ​​the object 5000. Therefore, an example of widening the null angle will be described. A number of methods can be used to widen the null angle.

[0050] Fig. 5 is a diagram for explaining an example of a plurality of null points in a region 151 of an object 5000. Fig. 5 may be a plan view when the object 5000 is viewed from the power transmitting device 10. As shown in Fig. 5, in the present disclosure, a method of arranging a plurality of null points 300P in the region 151 of the object 5000 will be described. When a plurality of null points 300P are arranged in the region 151 of the object 5000, the power of the power transmission radio wave for the object 5000 is weakened, and the power transmitting device 10 can perform appropriate power transmission.

[0051] In the present disclosure, this method is referred to as a multipoint null-constrained retrodirective method. The power transmitting device 10 can set multiple null points 300P for each of the multiple detected objects 5000. In an example shown in FIG. 5, the power transmitting device 10 sets multiple null points 300P in a matrix shape in the area 151 including the object 5000, but the null points 300P may be set only at the position where the object 5000 exists, or one or multiple null points 300P may be set. The distance between the multiple null points 300P may be constant or may be uneven. If the distance between the multiple null points 300P is constant, the null point arrangement is simplified. If the distance between the multiple null points 300P may be uneven, the number of null points 300P, etc. can be flexibly set according to the object 5000.

[0052] The outer shape of the multiple null points 300P may be a rectangle, a triangle, a circle, an ellipse, or any other shape, or any combination of these shapes. If the outer shape of the null points 300P may be a rectangle, a triangle, a circle, an ellipse, or any other shape, or any combination of these shapes, it becomes possible to arrange the null points 300P appropriately according to the object 5000.

[0053] The outer shape of the multiple null points 300P may be a shape that matches the object 5000, such as a person. If the outer shape of the multiple null points 300P may be a shape that matches the object 5000, such as a person, it becomes possible to appropriately arrange the null points 300P to match the object 5000.

[0054] Among the multiple null points 300P, the null points 300P may be arranged at positions that do not overlap the object 5000 when viewed from the power transmitting device 10 in the direction of the object 5000. If the null points 300P are arranged at positions that do not overlap the object 5000 when viewed from the power transmitting device 10 in the direction of the object 5000, the null points 300P can be arranged in advance with respect to the movement of the object 5000, and more appropriate null points 300P can be arranged.

[0055] The null points 300P may be arranged in space not only two-dimensionally but also one-dimensionally or three-dimensionally. Also, the null points 300P may be arranged in any combination of one-dimensional, two-dimensional, and three-dimensional arrangements depending on the location.

[0056] When multiple null points 300P are arranged one-dimensionally, the multiple null points 300P can be arranged on straight lines, curved lines, or a combination of these, and the null points 300P can be arranged appropriately to match the shape of the object 5000.

[0057] When multiple null points 300P are arranged three-dimensionally, it is possible to appropriately arrange the null points 300P in accordance with the thickness, width, etc. of the object 5000.

[0058] When multiple null points 300P are arranged in any combination of one-dimensional, two-dimensional, or three-dimensional arrangements depending on the location, the null points 300P can be appropriately arranged to match the shape of the object 5000, etc.

[0059] In the multipoint null-constrained retrodirective method, M array response vectors a i Once this is calculated, we generate matrix A using (Equation 8), and calculate the optimal weight vector w using (Equation 6) and (Equation 7). opt can be sought.

[0060] An example of a data flow from when weight generation unit 17 receives object information of a plurality of objects 5000 from detection unit 16 until it calculates an array response vector will be described with reference to Fig. 6. Fig. 6 shows a data flow illustrating an example of when weight generation unit 17 calculates an array response vector.

[0061] In the multi-point null-constrained retrodirective method for widening the null, for example, a direction and an area are used as object information of the object 5000. The direction can be, for example, a direction to the center of the area of ​​the object 5000. The area can be, for example, a horizontal angular spread of the object 5000. In the present disclosure, it is assumed that there are multiple objects 5000 different from the power receiving device 20 in the radio wave propagation environment, and the number of objects is p.

[0062] As shown in FIG. 6, for example, the weight generating unit 17 calculates a direction θ q and the region δ q When the minimum value θ in the direction is received, the following (Equation 13) and (Equation 14) are used to calculate the minimum value θ q min and the maximum value θ q max (Step S11), where q=1, 2, . . . , p. The weight generating unit 17 applies the minimum value θ q min and the maximum value θ q maxIf so, step S11 can be omitted.

number

number

[0063] Next, the weight generating unit 17 calculates, for example, a predetermined step size Δθ q θ q min From θ q max To cover all of the above, the null point L is calculated using the following formula (15). q is determined (step S12). In this disclosure, the function ROUNDUP(·) means a function that rounds up the decimal point to an integer. q is the direction θ of object 5000 q It may be constant regardless of the direction θ of the object 5000. q It may be changed every time.

number

[0064] Next, the weight generating unit 17 calculates the direction θ q (l) (l=1,2,...,L q ) is determined (step S13). q (l) is the direction θ q (1) ,θ q (2) , ,θ q (Lq) Including the direction θ q (l) (l=1,2,...,L q ) is, for example, the direction θ q It may be adjusted accordingly.

number

[0065] Subsequently, the weight generation unit 17, for example, sets M = L1 + L2 + ··· + L p and assigns M directions θ q (l) (l = 1, 2, ···, L q )(q = 1, 2, ···, p) to θ’ i (i = 1, 2, ···, M) (step S14).

[0066] Subsequently, if the null target direction is known, the weight generation unit 17 calculates M array response vectors a i (i = 1, 2, ···, M) as, for example, in the following (Equation 17) (step S15). Note that the M directions θ are θ = θ’ i (i = 1, 2, ···, M), and the impulse response Z’ i can be obtained from the direction θ’ i by the following (Equation 18). [Number] [Number]

[0067] As described above, the multi-point null-constrained retro-directive method can form nulls with broadened angles for a plurality of objects 5000. However, the multi-point null-constrained retro-directive method has a constraint condition of M < K. When the number of null points L q and the number of objects p increase, there is a possibility that this constraint condition cannot be satisfied. This is an issue of the multi-point null-constrained retro-directive method.

[0068] [Example of the weight generation method of the power transmission device according to the embodiment] Even when M ≥ K, a method for forming nulls with broadened angles for a plurality of objects 5000 will be described. This method is also effective when M < K, and thereby, it is expected to increase |w H a d |.

[0069] The K×M matrix A can be expressed as the following (Equation 19) by known singular value decomposition.

number

[0070] where U is a K×K unitary matrix. V is an M×M unitary matrix. Σ r are the singular values ​​σ1,σ2,...,σ of matrix A. r is a diagonal matrix of r×r with the diagonal elements σ1 ≥ σ2 ≥ ≥ σ r >0. Also, r is the rank of matrix A.

[0071] Moore-Penrose generalized inverse matrix A + Using these, is given by the following (Equation 20).

number

[0072] Here, Σ r ―1 are the reciprocals of the singular values ​​of matrix A, 1 / σ1, 1 / σ2, . . . , 1 / σ r It is an r × r diagonal matrix with the diagonal components as follows:

[0073] Therefore, (I-AA + ) is expressed as follows (Equation 21).

number

[0074] Here, I r ,I K-r are unit matrices of r×r and (Kr)×(Kr), respectively. In (Equation 21), the well-known I K =UU H =U H U, I M =VV H =V H We used the relationship, I K ,I Mare the K×K and M×M identity matrices respectively, and I in (I - AA + ) is equal to I K .

[0075] The K×K Gram matrix AA H can be expressed as in the following (Equation 22) by known eigenvalue decomposition. Note that the K×K Gram matrix AA H is a Gram matrix with the inner products of K×K vectors as its components.

Equation

[0076] Here, Σ r 2 is an r×r diagonal matrix with the eigenvalues λ1, λ2, ···, λ H of the Gram matrix AA r as its diagonal components, where λ1 ≥ λ2 ≥ ··· ≥ λ r > 0. And as is well known, λ i = σ i 2 (i = 1, 2, ···, r) holds.

[0077] Comparing (Equation 21) and (Equation 22), (Equation 21) can be derived if the Gram matrix AA H is eigenvalue - decomposed to obtain the unitary matrix U and the rank r. Thus, the above - mentioned (Equation 6) can be written as the following (Equation 23).

Equation

[0078] The rank of the K×M matrix A is r ≤ K and r ≤ M as is well known. If there is a constraint condition of M < K, then r ≤ M < K, so in (Equation 23), I K-r ≠ 0 and there exists a non - zero vector a’ d . On the other hand, when K ≤ M, r ≤ K ≤ M, but when r = K, I K-r = 0 and a’ dbecomes 0. Therefore, the denominator of the above-mentioned (Equation 7) becomes zero, and the optimal weight vector w opt does not exist. That is, the constraint condition M < K is a sufficient condition for the existence of the optimal weight.

[0079] Therefore, when the rank r of the matrix A is K, by reducing the rank (rank reduction), a’ d = 0 can be avoided. Although λ1 ≥ λ2 ≥ ··· ≥ λ K > 0, if λ r’+1 ≈ λ r’+2 ≈ ··· ≈ λ K ≈ 0, the approximate equation holds as shown in the following (Equation 24). However, r’ < K.

Equation

[0080] Here, Σ r’ 2 is an r’×r’ diagonal matrix with the eigenvalues λ1, λ2, ···, λ H of the Gram matrix AA r’ as diagonal elements.

[0081] Using the unitary matrix U and the rank r’ which are the results of (Equation 24), the non-zero vector a’ d can be calculated from the following (Equation 25). By using (Equation 25), even if r = K ≤ M, a’ d ≠ 0, so the optimal weight vector w opt can be obtained from the above-mentioned (Equation 7).

Equation

[0082] This principle can also be applied when r < K. Figure 7 is a diagram showing an example of the data flow from the array response vector to performing eigenvalue decomposition for rank reduction and calculating the vector a’ d .

[0083] As shown in FIG. 7, first, the weight generation unit 17 uses the above-described (Equation 8) to generate array response vectors a1, a2, ···, a M into a matrix (Step S21). As a result, the weight generation unit 17 generates a matrix A = [a1 a2 … a M .

[0084] Next, the weight generation unit 17 performs eigenvalue decomposition on the Gram matrix AA H (Step S22). The weight generation unit 17 obtains the rank r, eigenvalues λ H (i = 1, 2, ···, r), and unitary matrix U by eigenvalue decomposition of the Gram matrix AA i . However, let λ1 ≥ λ2 ≥ ··· ≥ λ r > 0. At this time, the rank r may be r = K or r < K.

[0085] Subsequently, the weight generation unit 17 determines r' (< r) from the eigenvalues λ i (i = 1, 2, ···, r) (Step S23). The weight generation unit 17 determines r' by finding r' (< r) such that λ i ≈ λ r’+1 ≈ ··· ≈ λ r’+2 ≈ 0. r

[0086] Subsequently, the weight generation unit 17 uses the unitary matrix U obtained by eigenvalue decomposition in Step S22, r' determined in Step S23, and the following (Equation 26) to calculate the matrix (I - AA + )(Step S24).

Equation

[0087] Subsequently, the weight generation unit 17 calculates a vector a' + from the matrix (I - AA d ) in (Equation 26) and the array response vector a d for the power receiving device 20, which is the estimation result of the estimation unit 14 (Step S25). Then, the weight generation unit 17 uses the calculated vector a'​d Applying this to the above (Equation 7) gives the optimal weight vector w opt can be generated.

[0088] As described above, even if the power transmitting device 10 uses a retrodirective scheme with multi-point null constraint using an array antenna, the constraint of null point (M)<number (K) of antenna elements 10A can be removed, and the null point can be determined without worrying about the constraint condition. As a result, the power transmitting device 10 can apply the retrodirective scheme with multi-point null constraint to multiple irradiation avoidance targets, thereby expanding the range of application.

[0089] For example, when a null is directed to all of a plurality of irradiation avoidance targets, the number of null points 300P increases. i Matrix A with (i=1, ,M) arranged horizontally and Hermitian transpose matrix A H AA, which is the product of H , and calculates the unitary matrix U and eigenvalues, and can determine the rank of the matrix A from the valid eigenvalues. opt By using this to emit 2000W of radio waves, it is possible to direct the null to multiple targets to be avoided.

[0090] [Modification of weight generation method of power transmission device according to embodiment] When the object information of the object 5000 includes, for example, distance and importance, a method of utilizing these will be described. For example, in the case of distance, it can be determined that an object at a close distance has a higher importance than an object at a far distance. Also, the importance may be for the entire object 5000, or may be for a part of the object 5000 (such as a specific direction or a specific area).

[0091] For example, in the case of multiple human bodies, the effect of 2000 W of radio waves on the human bodies differs between people who are close and people who are far away. Furthermore, the importance of each part of the human body differs. For this reason, the power transmitting device 10 associates the importance with the matrix A, thereby obtaining the array response vector a iWeighting is performed for each (i=1, ,M).

[0092] FIG. 8 shows a direction θ 2 as object information of a plurality of objects 5000 detected by the detection unit 16. q and the region δ q and the importance information for all 5000 objects Pr q 8 is a diagram showing an example of a data flow from receiving the vectors to calculating an array response vector. Compared to FIG. 6, step S14 in FIG. 8 is changed to step S14-1, and step S16 is added. In the following description, only the differences between FIG. 6 and FIG. 8 will be described.

[0093] When step S13 is completed, the weight generating unit 17 inputs θ q (l) Importance information Pr corresponding to q (q=1,2,...,p) is added, and the output is θ' i Pr' corresponding to i (i=1, 2, . . . , M) is added. The weight generation unit 17 adds the direction θ q (l) θ' i Similarly, the importance information Pr q Pr' i (step S14-1).

[0094] Next, the weight generating unit 17 generates M array response vectors a i (i=1, 2, . . . , M) (step S15). Then, the weight generating unit 17 calculates Pr' i (i=1,2,...,M) is used as the importance of matrix operation. i (Step S16). For example, the conversion is i α iAlternatively, a function for converting into Pr′ may be used, or a table T016 may be used as shown in FIG. 9. FIG. 9 is a diagram for explaining an example of step S16 in FIG. 8. The table T016 shown in FIG. 9 includes information indicating the relationship between the importance information (Pr′) from the detection unit 16 and the importance used in the matrix calculation, and is stored in the storage unit 17D. In FIG. 9, Pr′ i But, T n-1 ≦Pr' i <T n In the case of α i =S n This means that.

[0095] Fig. 10 shows the result of performing eigenvalue decomposition on the array response vector and the importance to reduce the rank of a' d 10 is a diagram showing an example of a data flow up to the calculation of .times. ...

[0096] As shown in FIG. 10, the weight generator 17 first calculates the array response vectors a1, a2, . . . , a M and importance α1,α2,···,α M (step S21-1). As a result, the weight generating unit 17 converts the array response vectors α1a1, α2a2, . . . , α M a M A matrix shown in the following (Equation 27) is generated by arranging the above.

number

[0097] The weight generation unit 17 reduces the rank by |w H a i | is no longer zero, but using (equation 27) i By changing the importance for each i The degree of deterioration can be controlled for each level of importance α i The larger the value, the less the deterioration can be achieved.

[0098] Next, the weight generating unit 17 calculates the Gram matrix A HPerform eigenvalue decomposition (step S22). The weight generation unit 17 performs eigenvalue decomposition on the Gram matrix AA H to obtain the rank r, eigenvalues λ i (i = 1, 2, ···, r), and unitary matrix U. However, let λ1 ≥ λ2 ≥ ··· ≥ λ r > 0. At this time, the rank r may be r = K or r < K.

[0099] Subsequently, the weight generation unit 17 determines r' (< r) from the eigenvalues λ i (i = 1, 2, ···, r) (step S23). Subsequently, the weight generation unit 17 uses the unitary matrix U obtained by eigenvalue decomposition in step S22, r' determined in step S23, and the above-mentioned (Equation 26) to calculate the matrix (I - AA + ) (step S24). Subsequently, the weight generation unit 17 calculates the vector a' + from the matrix (I - AA d ) in (Equation 26) and the array response vector a d which is the estimation result of the estimation unit 14 for the power receiving device 20 (step S25).

[0100] As described above, the power transmission device 10 determines the directions, regions, and importance of each array response vector a i of the irradiation avoidance targets, performs eigenvalue decomposition on the K × K Gram matrix AA H , and calculates non-negative eigenvalues λ i and the K × K unitary matrix U. The power transmission device 10 can generate a weight vector w i suitable for the importance of the irradiation avoidance targets by determining the rank r' from the eigenvalues λ opt .

[0101] [Power Receiving Device According to the Embodiment] FIG. 11 is a diagram showing an example of the configuration of a power receiving device 20 according to an embodiment. As shown in FIG. 11, the power receiving device 20 includes an antenna 21, a transmitting / receiving unit 22, a signal generating unit 23, and a power receiving unit 24. The power receiving device 20 of the present disclosure may be a mobile device. For example, such a power receiving device 20 may be a mobile battery, a smartphone, a camera, a vibration sensor, a biosensor, a temperature sensor, an alarm, or other device mounted on a moving object such as a drone or a car, an autonomous vehicle, a vibration sensor, a biosensor, a temperature sensor, an alarm, or the like whose installation position is variable. In the present disclosure, since the power receiving device 20 is a mobile device, the characteristics of the propagation channel based on the prescribed signal may change depending on the position of the power receiving device 20.

[0102] The antenna 21 is electrically connected to the transmitting / receiving unit 22. The antenna 21 is a power receiving antenna capable of receiving radio waves 2000W from the power transmitting device 10. For example, a patch antenna, a dipole antenna, a parabolic antenna, or the like can be used as the antenna 21. For example, the antenna 21 emits radio waves including a specified signal 1000, and receives radio waves 2000W including a transmission signal 2000 from the power transmitting device 10. The antenna 21 supplies a reception signal of the received radio waves 2000W to the transmitting / receiving unit 22.

[0103] The transmitting / receiving unit 22 is electrically connected to the signal generating unit 23 and the power receiving unit 24. The transmitting / receiving unit 22 causes the antenna 21 to radiate radio waves including the specified signal 1000 from the signal generating unit 23. The transmitting / receiving unit 22 supplies the power receiving unit 24 with a reception signal of the radio waves received by the antenna 21.

[0104] The signal generating unit 23 generates a specified signal 1000. The signal generating unit 23 causes the antenna 21 to emit radio waves including the specified signal 1000 via the transmitting / receiving unit 22. The signal generating unit 23 can generate the specified signal 1000 based on a transmission period. The signal generating unit 23 may be configured to generate a signal different from the specified signal 1000.

[0105] The power receiving unit 24 converts the radio waves of 2000 W received by the antenna 21 into a direct current and receives power using this direct current. The power receiving unit 24 converts the radio waves into a direct current using, for example, a known rectifier circuit. The power receiving unit 24 supplies the received power to, for example, a battery, a load, etc. The load includes, for example, mechanical equipment, an IoT (Internet of Things) sensor, an electronic device, a lighting device, etc.

[0106] An example of the functional configuration of the power receiving device 20 according to the present embodiment has been described above. Note that the above configuration described with reference to Fig. 11 is merely an example, and the functional configuration of the power receiving device 20 according to the present embodiment is not limited to this example. The functional configuration of the power receiving device 20 according to the present embodiment can be flexibly modified according to the specifications and operation.

[0107] [Example of Processing Procedure of Power Transmission Device According to the Embodiment] Fig. 12 is a diagram for explaining an example of a processing procedure of the power transmitting device 10 of the system 1 shown in Fig. 1. Fig. 13 is a diagram for explaining a data flow of the power transmitting device 10 shown in Fig. 12.

[0108] 12, in the system 1, the power receiving device 20 transmits a prescribed signal 1000. When the power transmitting device 10 receives radio waves including the prescribed signal 1000 at the array antenna 11, the power transmitting device 10 transmits an array response vector a d For example, as shown in FIG. 13, the power transmitting device 10 estimates the propagation channel characteristics of the reference signal 1000 included in the received signals received by the multiple antenna elements 11A in the estimation unit 14, and estimates the array response vector a d Returning to Fig. 12, when the process of step S111 ends, the power transmitting device 10 advances the process to step S131.

[0109] In addition, the power transmitting device 10 detects object information (direction, area, etc.) of the object 5000 different from the power receiving device 20 in the radio wave propagation environment based on the sensor information from the sensor unit 15 by using the detection unit 16 (step S121). For example, as shown in FIG. 13, when the detection unit 16 detects p objects 5000 as null targets, the power transmitting device 10 detects the directions θ1, θ2, . . . , θ P and areas δ1,δ2,...,δ P and supplies the weight to the weight generating unit 17. Returning to FIG. 12, when the process of step S121 is completed, the power transmitting device 10 advances the process to step S122.

[0110] The power transmitting device 10 performs array response vectorization and matrix calculation corresponding to null in the weight generating unit 17 (step S122). For example, as shown in FIG. 13, the power transmitting device 10 performs a vectorization in a direction θ q and the region δ q (q=1,2,...,P) to the array response vector a i (i=1, 2, . . . , M) is derived (step S171). In detail, for example, the array response vector a i Then, the power transmitting device 10 derives the array response vector a i (i=1,2,...,M) to the matrix (I-AA + ) is calculated (step S172). In detail, for example, using steps S21, S22, S23, S24, etc. of FIG. 7, the matrix (I-AA + ) can be calculated. The weight generating unit 17 stores the calculation result in the storage unit 17D. Returning to FIG. 12, when the process of step S122 ends, the power transmitting device 10 advances the process to step S131.

[0111] The power transmitting device 10 generates a transmission weight (step S131). For example, as shown in FIG. 13, the power transmitting device 10 performs a matrix-vector multiplication (step S173). In detail, the weight generating unit 17 of the power transmitting device 10 multiplies the array response vector a d and the matrix (I-AA +) to obtain the array response vector a d The power transmitting device 10 calculates the array response vector a′ calculated by the weight generating unit 17. d ' is normalized using (Equation 7) to obtain the optimal weight vector w opt (step S174). Returning to FIG. 12, when the process of step S131 ends, the power transmitting device 10 advances the process to step S132.

[0112] The power transmitting device 10 multiplies the transmission weight (step S132). For example, the power transmitting device 10 multiplies the transmission weight by the optimal weight vector w opt Based on weight information indicating the weight, the power transmitting device 10 multiplies the transmission signal 2000 for power supply from the transmission signal generating unit 12 by a weight for each of the plurality of antenna elements 11A and supplies the result to the transmitting / receiving circuit 13A. As a result, the power transmitting device 10 causes the plurality of antenna elements 11A to radiate radio waves 2000W including the transmission signal 2000 for power supply. In this case, the power transmitting device 10 constructively combines the radio waves 2000W at the power receiving device 20, but because a null is directed toward the object 5000, the radio waves are destructively combined at the object 5000.

[0113] The power receiving device 20 converts the received radio waves for power supply (2000 W) into a direct current, and uses the direct current to charge a battery or to operate using the charged power. After that, the power receiving device 20 transmits a prescribed signal 1000.

[0114] When the power transmitting device 10 receives radio waves including the prescribed signal 1000 at the array antenna 11, the power transmitting device 10 repeats the above-mentioned processing procedure to obtain the weight vector w opt and radiates radio waves 2000W of the transmission signal 2000 from the array antenna 11. In this way, even if the power receiving device 20 or the object 5000 moves, the power transmitting device 10 can maintain the state in which the radio waves 2000W are combined constructively at the power receiving device 20 and combined destructively at the object 5000.

[0115] The processing procedure of the power transmitting device 10 shown in FIG. 12 is to calculate the array response vector ad (step S111) and the array response vector a according to the direction and area of ​​the object 5000 i It is not necessary to synchronize the calculation of (i=1, 2, . . . , M) and the matrix calculation (step S122). For example, the period in which the prescribed signal 1000 is received and the period in which the detection unit 16 provides information may be different. In addition, for example, if there is no change in the direction and area of ​​the object 5000, the power transmitting device 10 may synchronize the past array response vector a i may also be used.

[0116] In FIG. 13 described above, the object information output from the detection unit is the direction θ of a plurality of objects 5000. q and region δ q The object information is the direction θ of the plurality of objects 5000. q and the region δ q and importance information Pr q In this case, since it can be explained by associating FIG. 6 with FIG. 8 and FIG. 7 with FIG. 10, the explanation here will be omitted.

[0117] In the above embodiment, the power transmitting device 10 has been described as including a linear array in which the antenna elements 11A of the array antenna 11 are equally spaced, but the present invention is not limited to this. i As long as it is possible to calculate the above, the arrangement of the multiple antenna elements 11A does not need to be an equally spaced linear array.

[0118] [Example of Determining the Rank of a Matrix According to an Embodiment] FIG. 14 is a flowchart showing a first example of determining the rank of a matrix. FIG. 15 is a flowchart showing a second example of determining the rank of a matrix. FIG. 16 is a flowchart showing a third example of determining the rank of a matrix. In the following description, a K×M matrix A=[a1a2...a M ], the rank of r≦K,M, then we have a K×K Gram matrix AA H The rank of is also r, and there are r non-negative eigenvalues ​​λ i Take the eigenvalue λ i For i = 1, 2, …, r, λ1 ≥ λ2 ≥ ≥ λr >0. As a condition, the eigenvalue λ i = 0(r+1,r+2,…,K), and add λ i (i=1,2,…,K), i.e., λ1 ≥ λ2 ≥ ≥ λ K >0. Eigenvalue λ i The sum of sum(λ i ) can be expressed as follows (Equation 28). i ave(λ i ) can be expressed as follows (Equation 29). i The maximum value of max(λ i ) can be expressed as follows (Equation 30).

number

number

number

[0119] 14, the weight generation unit 17 of the power transmission device 10 executes variable i=0 (step S211). For example, the weight generation unit 17 sets the variable i to zero, which is an initial value. Then, the weight generation unit 17 increments the variable i (step S212). For example, the weight generation unit 17 adds 1 to the variable i.

[0120] Next, the weight generating unit 17 calculates the eigenvalue λ i The sum of the eigenvalues ​​λ up to the number K of antenna elements 11A i For example, the weight generating unit 17 determines whether the eigenvalue λ is greater than the sum of the eigenvalues ​​λ i The sum of the eigenvalues ​​λ up to the number K of antenna elements 11A i The weight generating unit 17 judges whether the eigenvalue λ is greater than the sum of the eigenvalues ​​λ1 to λ2. i The sum of the eigenvalues ​​λ up to the number K of antenna elements 11A iIf it is determined that the sum up to is not greater than the value multiplied by the predetermined ratio (No in step S213), the process returns to step S212 already described and continues. i The sum of the eigenvalues ​​λ up to the number K of antenna elements 11A i If it is determined that the sum up to is greater than the value obtained by multiplying the sum by a predetermined ratio (Yes in step S213), the process proceeds to step S214. The weight generation unit 17 sets the value of the variable i to the rank (step S214). As a result, the weight generation unit 17 calculates the Gram matrix A H The unitary matrix U and eigenvalue λ obtained by eigenvalue decomposition of i Calculate the effective eigenvalue λ i The rank can be determined from this.

[0121] In the example illustrated in FIG. 15, the weight generating unit 17 of the power transmitting device 10 executes a variable i=0 (step S221). Then, the weight generating unit 17 increments the variable i (step S222). Then, the weight generating unit 17 calculates the eigenvalue λ i There are multiple eigenvalues ​​λ i For example, the weight generating unit 17 determines whether the eigenvalue λ is smaller than a value obtained by multiplying the average value of λ by a predetermined ratio (step S223). i The weight generating unit 17 judges whether the eigenvalue λ is smaller than the value obtained by multiplying the calculation result of the above (Equation 29) by a ratio of 0.01. i There are multiple eigenvalues ​​λ i If it is determined that the eigenvalue λ is not smaller than the value obtained by multiplying the average value of λ by the predetermined ratio (No in step S223), the process returns to step S222 already described and continues. i There are multiple eigenvalues ​​λ i When it is determined that the average value of the weights i-1 is smaller than the value obtained by multiplying the average value of the weights i-1 by a predetermined ratio (Yes in step S223), the process proceeds to step S224. The weight generation unit 17 sets the value of the variable i-1 to the rank (step S224). As a result, the weight generation unit 17 calculates the Gram matrix A HThe unitary matrix U and eigenvalue λ obtained by eigenvalue decomposition of i Calculate the effective eigenvalue λ i The rank can be determined from this.

[0122] In the example illustrated in FIG. 16, the weight generating unit 17 of the power transmitting device 10 executes variable i=0 (step S231). Then, the weight generating unit 17 increments the variable i (step S232). Then, the weight generating unit 17 calculates the eigenvalue λ i There are multiple eigenvalues ​​λ i For example, the weight generating unit 17 determines whether the eigenvalue λ is smaller than the maximum value of λ multiplied by a predetermined ratio (step S233). i The weight generating unit 17 judges whether the eigenvalue λ is smaller than the value obtained by multiplying the calculation result of the above (Equation 30) by a ratio of 0.01. i There are multiple eigenvalues ​​λ i If it is determined that the eigenvalue λ is not smaller than the maximum value of λ multiplied by the predetermined ratio (No in step S233), the process returns to step S232 already described and continues. i There are multiple eigenvalues ​​λ i When it is determined that the value of the variable i-1 is smaller than the value obtained by multiplying the maximum value of the variable i-1 by a predetermined ratio (Yes in step S233), the process proceeds to step S234. The weight generation unit 17 sets the value of the variable i-1 to the rank (step S234). As a result, the weight generation unit 17 calculates the Gram matrix A H The unitary matrix U and eigenvalue λ obtained by eigenvalue decomposition of i Calculate the effective eigenvalue λ i The rank can be determined from this.

[0123] The weight generating unit 17 is not limited to the first to third examples of the method for determining the rank of a matrix. For example, the weight generating unit 17 may generate a value obtained by multiplying the standard deviation by a predetermined value N as a plurality of eigenvalues ​​λ i The rank of the matrix may be determined by subtracting the average value of

[0124] [System operation example] 1, when multiple objects 5000 are present in the vicinity between the power transmitting device 10 and the power receiving device 20, the power transmitting device 10 can detect the directions of the multiple objects 5000 based on the sensor information of the sensor unit 15. When the power receiving device 20 emits radio waves including a prescribed signal 1000, the main paths are a path that goes directly to the power transmitting device 10 and a path that is reflected by the multiple objects 5000 and goes back to the power transmitting device 10. In this case, the power transmitting device 10 estimates the propagation channel characteristics of the radio waves including the prescribed signal 1000 received by the array antenna 11, and calculates an array response vector a i The power transmitting device 10 estimates the directions θ1, θ2, . . . , θ of the object 5000 different from the power receiving device 20 based on the sensor information from the sensor unit 15. M The power transmitting device 10 detects the array response vector a corresponding to the null depending on the direction of the object 5000. i Calculate the array response vector a i The power transmitting device 10 converts the Gram matrix A H Decompose A into eigenvalues ​​to obtain the rank r and eigenvalue λ of matrix A. i (i=1,2,…,r) and calculate multiple eigenvalues ​​λ i The power transmitting device 10 reduces the rank r based on the first eigenvalue that satisfies a predetermined condition from the rank r. d Using the above (equation 23), vector a' d Calculate the vector a' in the above (Equation 7). d Applying the weight vector W out The power transmitting device 10 determines the generated weight vector W out is generated as a transmission weight of the array antenna 11 that transmits the transmission signal 2000 to the power receiving device 20. The power transmitting device 10 generates the optimal weight vector W opt The radio wave 2000 W of the transmission signal 2000 multiplied by is radiated from the multiple antenna elements 11 A of the array antenna 11 .

[0125] As a result, even if the power transmitting device 10 receives the specified signal 1000 from the direction of the object 5000, the power transmitting device 10 can direct the radiated radio waves 2000W in the direction of the power receiving device 20 and can suppress the radiation of the radio waves 2000W toward the multiple objects 5000. As a result, even if multiple objects 5000 are present in the propagation environment, the power transmitting device 10 can suppress the radio waves 2000W toward the multiple objects 5000, thereby achieving safe wireless power transmission.

[0126] Even if a plurality of objects 5000 are present in the propagation environment, the power transmitting device 10 detects the directions of the plurality of objects 5000 and calculates a weight vector W so as to direct a null to each of the plurality of objects 5000. opt In the present disclosure, the weight generating unit 17 may generate the transmission weights so that the gain in the direction of the object is within a predetermined gain range from null. For example, when null is x [dB], the weight generating unit 17 may generate the transmission weights so that the gain in the direction of the object 5000 is within a gain range of x [dB] to y [dB] of null.

[0127] In the above embodiment, the power transmitting device 10 has been described as including a linear array of antenna elements 11A of the array antenna 11 spaced at equal intervals, but is not limited to this. i As long as it is possible to calculate the above, the arrangement of the multiple antenna elements 11A does not need to be an equally spaced linear array.

[0128] Characteristic embodiments have been described in order to fully and clearly disclose the technology according to the attached claims. However, the attached claims should not be limited to the above-mentioned embodiments, but should be configured to embody all modifications and alternative configurations that a person skilled in the art can create within the scope of the basic matters shown in this specification. The contents of this disclosure can be modified and amended by a person skilled in the art based on this disclosure. Therefore, these modifications and amendments are included in the scope of this disclosure. For example, in each embodiment, each functional unit, each means, each step, etc. can be added to other embodiments so as not to be logically contradictory, or can be replaced with each functional unit, each means, each step, etc. of other embodiments. In each embodiment, multiple functional units, each means, each step, etc. can be combined into one or divided. In addition, each embodiment of the present disclosure described above is not limited to being faithfully implemented to each of the embodiments described respectively, and can be implemented by combining each feature or omitting a part as appropriate.

[0129] For example, the appended claims may be modified so that the function of the weight generation unit 17 of the power transmitting device 10 is realized as a transmission weight generation device. The transmission weight generation device may be realized, for example, by various devices and may be configured to be incorporated into the power transmitting device 10 of the above embodiment, or may be configured to provide information such as transmission weights to the power transmitting device 10 from outside the power transmitting device 10.

[0130] [Appendix 1] A transmission weight generation device that generates transmission weights for an antenna having a plurality of antenna elements based on a received signal transmitted from a power receiving device and information relating to an object other than the power receiving device, so that a strength of radio waves transmitted to the power receiving device by the antenna having a plurality of antenna elements is equal to or less than a predetermined strength to the object, a transmission weight generation device that calculates a Gram matrix from a matrix of an array response vector based on a specified signal transmitted from the power receiving device and the number of multiple null points with respect to the object and directions of the null points, obtains a unitary matrix, a rank, and multiple eigenvalues ​​by eigenvalue decomposition of the Gram matrix, reduces the rank based on a first eigenvalue that satisfies a predetermined condition from the multiple eigenvalues, and generates a transmission weight of the antenna that transmits the transmission signal to the power receiving device using the rank and the unitary matrix. [Appendix 2] A power receiving device; a transceiver unit that transmits a transmission signal to a power receiving device and receives a reception signal transmitted from the power receiving device by an antenna having a plurality of antenna elements; a power transmitting device having a weight generating unit that controls the directivity of the antenna that transmits the transmission signal based on the received signal and information about an object other than the power receiving device so that the strength of the radio wave that transmits the transmission signal to the object is equal to or less than a predetermined value; Equipped with The weight generation unit a first eigenvalue that satisfies a predetermined condition from among the plurality of eigenvalues; and a transmission weight for the antenna that transmits the transmission signal to the power receiving device is generated using the first eigenvalue and the unitary matrix. [Explanation of symbols]

[0131] 1 System 10 Power transmission equipment 11 Array Antenna 11A Antenna element 12 Transmission signal generator 13 Transmitter / receiver 14 Estimation part 15 Sensor section 16 Detection section 17 Weight Generation Unit 17D Storage section 18 Multiplication section 20 Power receiving device 21 Antenna 22 Transmitter / receiver 23 Signal Generator 24 Power receiving section 151 areas 200B Reference point 200P receiving point 300P Null point 1000 regulation signal 2000 Transmitted signal 2000W radio wave 5000 objects W opt Weight Vector

Claims

1. a transceiver unit that transmits a transmission signal to a power receiving device and receives a reception signal transmitted from the power receiving device by an antenna having a plurality of antenna elements; a weight generating unit that controls the directivity of the antenna that transmits the transmission signal based on the received signal and information about an object other than the power receiving device so that the strength of the radio wave that transmits the transmission signal to the object is equal to or less than a predetermined value; Equipped with The weight generation unit a power transmitting device that calculates a Gram matrix from a matrix of an array response vector based on a specified signal transmitted from the power receiving device and a number of multiple null points with respect to the object and directions of the null points, obtains a unitary matrix, a rank, and multiple eigenvalues ​​by eigenvalue decomposition of the Gram matrix, reduces the rank based on a first eigenvalue among the multiple eigenvalues ​​that satisfies a predetermined condition, and generates a transmission weight of the antenna that transmits the transmission signal to the power receiving device using the rank and the unitary matrix.

2. The weight generation unit The number of the plurality of antenna elements is K, the number of the plurality of null points is M, the matrix of K×M is A, and the complex conjugate transpose (Hermitian transpose) of matrix A is A Ｈ Let U be the unitary matrix, r be the rank, and λ be the eigenvalue. ｉ (i=1, 2, ..., r), Gram matrix AA Ｈ Decompose the rank r and the eigenvalue λ ｉ (i = 1, 2, ..., r) and calculate multiple eigenvalues ​​λ ｉ The rank r is reduced based on the first eigenvalue that satisfies the predetermined condition among the above, and the array response vector a generated based on the rank r, the unitary matrix U, and the specified signal is ｄ and vector a' using the following (Equation 101): ｄ The vector a′ is calculated and added to the following (Equation 102): ｄ Applying the weight vector W ｏｕｔ and the weight vector W ｏｕｔ The power transmitting device according to claim 1 , wherein the power transmitting device generates a transmission weight of the antenna that transmits the transmission signal to the power receiving device. [0031] [0032]

3. The weight generation unit 2. The power transmitting device according to claim 1, further comprising: a Gram matrix is ​​calculated from a matrix of an array response vector based on a specified signal transmitted from the power receiving device, a number of multiple null points for the object, directions of the null points, and importance of the directions; a unitary matrix, a rank, and multiple eigenvalues ​​are obtained by eigenvalue decomposition of the Gram matrix; the rank is reduced based on a first eigenvalue that satisfies a predetermined condition from the multiple eigenvalues; and a transmission weight of the antenna that transmits the transmission signal to the power receiving device is generated using the rank and the unitary matrix.

4. Let K be the number of the plurality of antenna elements, M be the number of the plurality of null points, and A be the matrix of K×M; The matrix A obtained by matrixing the array response vector based on the importance of the direction is given by: α ｉ The power transmitting device according to claim 3 , wherein, when (i=1, 2, . . . , M) is a degree of importance for a direction, the matrix is ​​given by the following (Equation 103). [Equation 33]

5. The power transmitting device according to claim 2 , wherein M, which is a number of the plurality of null points, is a natural number greater than K, which is a number of the plurality of antenna elements.

6. The weight generation unit K x K Gram matrix AA Ｈ r eigenvalues ​​λ of ｉ (i = 1, 2, ..., r), and λ １ ≧λ ２ ≧・・・≧λ ｒ >0, and the variable i is incremented sequentially from 0 to obtain the eigenvalue λ ｉ The sum of the eigenvalues ​​λ up to the number of the antenna elements ｉ The power transmitting device according to claim 5 , wherein the value of the variable i is set to the rank when the value becomes larger than a value obtained by multiplying a sum of the powers up to the rank by a predetermined ratio.

7. The weight generation unit K x K Gram matrix AA Ｈ r eigenvalues ​​λ of ｉ (i = 1, 2, ..., r), and λ １ ≧λ ２ ≧・・・≧λ ｒ >0, and the eigenvalue λ ｉ is a plurality of eigenvalues ​​λ ｉ The power transmitting device according to claim 5, wherein when the value of the variable i-1 becomes smaller than a value obtained by multiplying an average value of the variable i-1 by a predetermined ratio, the value of the variable i-1 is set as the rank.

8. The weight generation unit K x K Gram matrix AA Ｈ r eigenvalues ​​λ of ｉ (i = 1, 2, ..., r), and λ １ ≧λ ２ ≧・・・≧λ ｒ >0, and the eigenvalue λ ｉ is a plurality of eigenvalues ​​λ ｉ The power transmitting device according to claim 5, wherein when the value of the variable i-1 becomes smaller than a value obtained by multiplying the maximum value of the variable i-1 by a predetermined ratio, the value of the variable i-1 is set as the rank.

9. The power transmitting device according to claim 2 , further comprising a sensor unit that detects a direction of the object different from the power receiving device.

10. The weight generation unit The power transmitting device according to claim 9 , wherein the directivity is controlled so that a radio wave intensity of the radio wave that transmits the transmission signal in a first direction, which is a direction of the object relative to the antenna, is equal to or lower than a predetermined value.

11. The prescribed signal is a signal capable of estimating characteristics of a propagation channel, The weight generation unit generates a weight based on the characteristics of the propagation channel of the specified signal and the first direction. The power transmitting device according to claim 10 , further comprising: a power transmitting unit configured to generate a transmission weight for controlling the directivity based on the power transmitting unit.

12. The power transmitting device according to claim 9 , wherein the weight generating unit generates the transmission weights so that a gain in a direction of the object with respect to the antenna is within a predetermined gain range from null.

13. The power transmitting device according to claim 9 , wherein the power receiving device is a mobile device, and the characteristics of a propagation channel based on the specified signal can change depending on a position of the power receiving device.

14. a transmitting / receiving step of transmitting a transmission signal to a power receiving device and receiving a reception signal transmitted from the power receiving device by an antenna having a plurality of antenna elements; a weight generation process for controlling the directivity of the antenna that transmits the transmission signal based on the received signal and information about an object other than the power receiving device so that the strength of the radio wave that transmits the transmission signal to the object is equal to or less than a predetermined value; Equipped with The weight generating step includes: a control method comprising: calculating a Gram matrix from a matrix of an array response vector based on a specified signal transmitted from the power receiving device and the number of multiple null points with respect to the object and directions of the null points; determining a unitary matrix, a rank, and multiple eigenvalues ​​by eigenvalue decomposition of the Gram matrix; lowering the rank based on a first eigenvalue that satisfies a predetermined condition from the multiple eigenvalues; and generating a transmission weight for the antenna that transmits the transmission signal to the power receiving device using the rank and the unitary matrix.

15. On the computer, a transmitting / receiving step of transmitting a transmission signal to a power receiving device and receiving a reception signal transmitted from the power receiving device by an antenna having a plurality of antenna elements; a weight generation process for controlling the directivity of the antenna that transmits the transmission signal based on the received signal and information about an object other than the power receiving device so that the strength of the radio wave that transmits the transmission signal to the object is equal to or less than a predetermined value; Run the command, The weight generating step includes: a control program for executing a process of: calculating a Gram matrix from a matrix of an array response vector based on a specified signal transmitted from the power receiving device and the number of multiple null points with respect to the object and directions of the null points; determining a unitary matrix, a rank, and multiple eigenvalues ​​by eigenvalue decomposition of the Gram matrix; lowering the rank based on a first eigenvalue that satisfies a predetermined condition from the multiple eigenvalues; and generating a transmission weight of the antenna that transmits the transmission signal to the power receiving device using the rank and the unitary matrix.

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