JP2024052265A - Wireless power transmission system, power transmitting system, power receiving system, power transmitting device, power receiving device and space photovoltaic power generation satellite - Google Patents

Abstract

To provide a system capable of performing stable wireless power transmission from a power transmitting device, which is located at a high altitude, to a power receiving device.SOLUTION: A system comprises: a plurality of power transmitting devices 100 each mounted on a floating body 10, which is located at a predetermined altitude, and transmitting a transmission signal for wireless power transmission via an electromagnetic wave in a predetermined frequency; and one or more power receiving devices 20 outputting power by performing phase synthesis on a plurality of reception signals obtained by receiving a plurality of transmission signals transmitted from the plurality of power transmitting devices. The frequency of the electromagnetic wave may also be 300 [GHz] or lower and the electromagnetic wave may also be a microwave. The electromagnetic wave may also be an electromagnetic wave of a beam shape which is formed so as to have directivity from the power transmitting device toward the power receiving device. The floating body may also be a HAPS, balloon or drone located in the stratosphere. The power receiving device may also be located on the ground, on the sea or on the lake or may also be located in a low-altitude space lower than the power transmitting device.SELECTED DRAWING: Figure 1

Description

The present invention relates to wireless power transfer (WPT).

Conventionally, systems that transmit power using electromagnetic waves are known. For example, Patent Document 1 discloses a power supply system that includes a power transmission system (power transmission device) in space that transmits electrical energy as a microwave beam, and a power receiving system (power receiving device) on the ground that receives the microwave beam transmitted from the power transmission system.

JP 2008-259392 A

In conventional systems that use electromagnetic waves to transmit power, there is a need to achieve stable wireless power transmission from a power transmitting device located at a high altitude to a power receiving device located on the ground, sea, or lake, or in space at a low altitude.

The system according to the first aspect of the present invention is a system for wireless power transmission. This system includes a plurality of power transmission devices mounted on a floating body located at a predetermined altitude and transmitting transmission signals for wireless power transmission via electromagnetic waves of a predetermined frequency, and one or more power receiving devices that output electric power by phase-combining a plurality of received signals that receive the plurality of transmission signals transmitted from the plurality of power transmission devices.

In the system according to the first aspect, the power receiving device may transmit a pilot signal to the power transmitting devices, and the power transmitting devices may be time-synchronized with each other, and may determine the transmission timing of the transmission signal for wireless power transmission based on the reception result of the pilot signal received from the power receiving device so that the transmission signals for wireless power transmission transmitted from the power transmitting devices reach the power receiving device in phase.

In the system according to the first aspect, the frequency of the electromagnetic waves may be 300 GHz or less.

In the system according to the first aspect, the electromagnetic waves may be microwaves.

In the system according to the first aspect, the electromagnetic waves may be beam-shaped electromagnetic waves formed to have directivity from the power transmitting device to the power receiving device.

In the system according to the first aspect, the float may be a HAPS, a balloon, or a drone located in the stratosphere.

In the system according to the first aspect, the power receiving device may be located on land, sea or lake, or in a space at a low altitude lower than the power transmitting device.

The power transmission device according to the first aspect of the present invention is a power transmission device for wireless power transmission. This power transmission device is mounted on a levitation body located at a predetermined altitude, and includes a transmission unit that transmits a transmission signal for wireless power transmission via electromagnetic waves of a predetermined frequency.

The power transmission device according to the first aspect may include a synchronization processing unit that performs time synchronization with other power transmission devices that have a common power transmission target, and the transmission unit may determine the transmission timing of the transmission signal for wireless power transmission based on the reception result of a pilot signal received from the power receiving device so that the transmission signals for wireless power transmission transmitted from the multiple power transmission devices arrive at the power receiving device in the same phase.

The power transmission system according to the first aspect of the present invention includes a plurality of the power transmission devices.

The power receiving device according to the first aspect of the present invention is a power receiving device for wireless power transmission. This power receiving device includes a receiving unit that receives transmission signals for wireless power transmission via electromagnetic waves of a predetermined frequency from a plurality of power transmitting devices each mounted on a levitation body located at a predetermined altitude, and a combining unit that combines a plurality of received signals in phase that have received the plurality of transmission signals.

The power receiving device according to the first aspect may include a transmission unit that transmits pilot signals to the multiple power transmitting devices.

The system according to the second aspect of the present invention is a system for wireless power transmission. This system includes a power transmitting device mounted on a floating body located at a predetermined altitude, which receives a transmission signal for wireless power transmission from an external device via electromagnetic waves of a first frequency, converts the frequency of the transmission signal for wireless power transmission to a second frequency lower than the first frequency, and transmits the transmission signal for wireless power transmission via electromagnetic waves of the second frequency, and a power receiving device which receives the transmission signal transmitted from the power transmitting device and outputs electric power.

In the system according to the second aspect, the electromagnetic wave of the first frequency may be a millimeter wave, a terahertz wave, or a light wave, and the electromagnetic wave of the second frequency may be a microwave.

In the system according to the second aspect, the electromagnetic waves of the first frequency may be beam-shaped electromagnetic waves formed to have a directivity from an external device toward the power transmitting device, and the electromagnetic waves of the second frequency may be beam-shaped electromagnetic waves formed to have a directivity from the power transmitting device toward the power receiving device.

In the system according to the second aspect, the external device may be a space solar power satellite located in space outside the atmosphere, and the floating body may be a HAPS, a balloon, or a drone located in the stratosphere.

In the system according to the second aspect, the power receiving device may be located on land, sea or lake, or in space at a lower altitude than the power transmitting device.

The power transmission device according to the second aspect of the present invention is a power transmission device for wireless power transmission. This power transmission device is mounted on a floating body located at a predetermined altitude, and includes a receiving unit that receives a transmission signal for wireless power transmission via electromagnetic waves of a first frequency, a converting unit that converts the frequency of the transmission signal for wireless power transmission to a second frequency that is lower than the first frequency, and a transmitting unit that transmits the transmission signal for wireless power transmission via electromagnetic waves of the second frequency.

The system according to the third aspect of the present invention is a system for wireless power transmission. This system includes a space solar power generation satellite located at an altitude higher than the atmosphere and transmitting multiple wireless power transmission transmission signals in multiple beams via electromagnetic waves of a predetermined frequency, and multiple power receiving devices mounted on multiple floating bodies located at a predetermined altitude lower than the space solar power generation satellite and receiving each of the multiple wireless power transmission transmission signals transmitted in multiple beams from the space solar power generation satellite.

In the system according to the third aspect, the electromagnetic waves may be millimeter waves, terahertz waves, or light waves.

In the system according to the third aspect, the float may be a HAPS, a balloon, or a drone located in the stratosphere.

The space solar power satellite according to the third aspect of the present invention is located at an altitude higher than the atmosphere and has a transmitter that transmits multiple transmission signals for wireless power transmission in multiple beams via electromagnetic waves of a predetermined frequency to multiple power receiving devices mounted on multiple floating bodies located at a predetermined altitude lower than the space solar power satellite.

The power receiving device according to the third aspect of the present invention is a power receiving device for wireless power transmission. This power receiving device is mounted on each of a plurality of floating bodies located at a predetermined altitude lower than the space solar power generation satellite, and includes a receiving unit that receives a transmission signal for wireless power transmission transmitted from the space solar power generation satellite via electromagnetic waves of a predetermined frequency.

The wireless power transmission power receiving system according to the third aspect of the present invention includes a plurality of the power receiving devices.

The present invention enables stable wireless power transmission from a power transmitting device located at a high altitude to a power receiving device.

FIG. 1 is an explanatory diagram showing an example of a schematic configuration of a system according to a first embodiment. FIG. 2 is a block diagram showing an example of the main configuration of a HAPS and a base station constituting the wireless power transmission (WPT) system of the first embodiment. 1A is a graph showing a combined signal when the phases of signals received by a base station due to transmission signals from multiple HAPSs are not aligned, and FIG. 1B is a graph showing a combined signal when the phases of signals received by a base station due to transmission signals from multiple HAPSs are aligned (phase combined). FIG. 11 is an explanatory diagram showing an example of a method for combining phases so that the phases of a plurality of received signals are matched; FIG. 11 is an explanatory diagram showing an example of a schematic configuration of a system according to a second embodiment. FIG. 11 is a block diagram showing an example of the main configuration of a HAPS and a base station constituting a wireless power transmission (WPT) system of a second embodiment. FIG. 11 is an explanatory diagram showing an example of a schematic configuration of a system according to a third embodiment. FIG. 11 is a block diagram showing an example of a main configuration of a HAPS constituting a wireless power transmission (WPT) system of embodiment 3.

The following describes an embodiment of the present invention with reference to the drawings.

[Embodiment 1]
A wireless power transmission (WPT) system according to one embodiment described in this specification is a large-space distributed power supply system capable of stably supplying power from multiple power transmitting devices mounted on multiple floating bodies (e.g., HAPS, balloons, drones) located in a distributed manner in the stratosphere or other locations in the sky to power receiving devices located on the ground, sea, lakes, etc., or to power receiving devices mounted on drones located in low-altitude space.

FIG. 1 is an explanatory diagram showing an example of a schematic configuration of a system according to the first embodiment.
The system of the first embodiment is a system for wireless power transmission (WPT), and includes a plurality of power transmitting devices mounted on levitating bodies located at a predetermined altitude, and one or more power receiving devices. Each of the plurality of power transmitting devices transmits a transmission signal for wireless power transmission via electromagnetic waves of a predetermined frequency. The one or more power receiving devices output power by phase-combining a plurality of received signals that are received from the plurality of power transmitting devices mounted on the respective levitating bodies.

The floating body is, for example, a HAPS, a balloon, or a drone. In this embodiment, a high-altitude platform station, HAPS (also called a "high-altitude pseudo satellite") 10, is used as the floating body. HAPS 10 is equipped with a communication relay device, is located in an airspace at a predetermined altitude, and forms a three-dimensional cell (three-dimensional area) in a cell formation target airspace at the predetermined altitude. The airspace in which HAPS 10 is located is, for example, a stratospheric airspace with an altitude of 11 km or more and 50 km or less. This airspace may be an airspace with an altitude of 15 km or more and 25 km or less where the weather conditions are relatively stable, and may particularly be an airspace with an altitude of approximately 20 km. The cell formation target airspace may be above the sea, a river, or a lake.

The relay communication device of HAPS10 forms a beam toward the ground for wireless communication with a terminal device, which is a mobile station. The terminal device may be a communication terminal module built into a drone, which is an aircraft such as a small remote-controlled helicopter, or it may be a user device used by a user inside an airplane (aircraft).

The relay communication device of HAPS10 is connected to the core network of the mobile communication network via a feeder station, which is a relay station located on land, sea, or lake. Communication between HAPS10 and the feeder station may be performed by wireless communication using radio waves such as microwaves, or by optical communication using laser light, etc.

Each HAPS 10 may autonomously control its own flight movement and processing at the relay communication station by executing a control program with a control unit configured with an internally built computer or the like. For example, HAPS 10 may acquire its own current position information (e.g., GPS (Global Positioning System) position information), pre-stored position control information (e.g., flight schedule information), position information of other HAPS located in the vicinity, and the like, and autonomously control its flight movement and processing at the relay communication device based on that information.

Furthermore, the flight movement of HAPS10 and the processing by the relay communication device may be controlled by a remote control device serving as a management device provided in a communication center of a mobile communication network or the like. Communication between HAPS10 and the remote control device is performed by a HAPS control communication station, which is a facility on the ground or at sea. The HAPS control communication station preferably uses an omnidirectional antenna so that it can accommodate multiple HAPS10, but a directional antenna may also be used. A GCS (Ground Control System) (ground control station) can be used as such a HAPS control communication station.

The wireless communication between HAPS10 and the HAPS control communication station requires high reliability and low latency because it includes communication for controlling the flight movement and cell optimization of HAPS10. Therefore, it is preferable to use a lower frequency band for the wireless communication between HAPS10 and the HAPS control communication station than the frequency band used for wireless communication via the feeder link of the mobile communication performed between HAPS10 and the feeder station. For example, if a gigahertz (GHz) frequency band is used for the wireless communication performed between HAPS10 and the feeder station, a megahertz (MHz) frequency band is used for the wireless communication between HAPS10 and the HAPS control communication station.

When controlled by a remote control device, HAPS10 may incorporate a control communication terminal device (e.g., a mobile communication module) so that it can receive control information from the remote control device, and may be assigned terminal identification information (e.g., an IP address, a telephone number, etc.) so that it can be identified by the remote control device. The MAC address of the communication interface may be used to identify the control communication terminal device. HAPS10 may also transmit information such as information related to the flight movement of itself or surrounding HAPS, processing by relay communication devices, and observation data acquired by various sensors, etc., to a specified destination such as a remote control device.

The power receiving device is a power supply target that is supplied with power by wireless power transmission (WPT) from a power transmitting device on the HAPS 10, and is not particularly limited. In this embodiment, for example, it is a power receiving device located on the ground, sea, or lake (e.g., a mobile communication base station, mobile station, or other facility device), or a power receiving device located in space at a low altitude lower than the position of the HAPS 10 (e.g., another HAPS, a balloon, a drone, an airplane (aircraft), or other floating object). This embodiment is an example in which a mobile communication base station 20 installed on the ground is used as the power receiving device.

The base station 20 is equipped with, for example, a plurality of array antennas 210 having a large number of antenna elements, and can communicate with a plurality of terminal devices (for example, UEs (mobile stations) for mobile communication and IoT devices, hereinafter also referred to as "UE20") using a massive MIMO (hereinafter also referred to as "mMIMO") transmission method. mMIMO is a wireless transmission technology that realizes large-capacity, high-speed communication by transmitting and receiving data using the array antenna 210. In addition, communication can be performed using a MU (Multi User)-MIMO transmission method that performs beamforming, which forms beams for each of the plurality of UE20 in a time-division or simultaneously. By performing MU-MIMO transmission using a multi-element array antenna, communication can be performed by directing an appropriate beam to each UE20 according to the communication environment of each UE20, thereby improving the communication quality of the entire cell. In addition, communication with a plurality of UE20 can be performed using the same wireless resources (time and frequency resources), thereby expanding the system capacity.

FIG. 2 is a block diagram showing an example of the main configuration of the HAPS 10 and the base station 20 that constitute the wireless power transmission (WPT) system of the first embodiment.
The HAPS 10 includes a communication relay device 100 as a power transmitting device and an antenna 110. The antenna 110 is, for example, an array antenna having a large number of antenna elements. There may be a single antenna 110 or multiple antennas 110. For example, multiple antennas 110 may be arranged corresponding to multiple sector cells.

The communication relay device 100 includes a communication signal processing unit 120, a wireless processing unit 130, a power transmission control unit 140, and a NW communication unit 150. The communication signal processing unit 120 processes signals such as control information transmitted and received between the base station 20. The wireless processing unit 130 transmits a transmission signal generated by the communication signal processing unit 120 from the antenna 110 to the base station 20, and outputs a received signal received from the base station 20 via the antenna 110 to the communication signal processing unit 120.

The power transmission control unit 140 sends control information from the base station 20 to the communication signal processing unit 120, and generates a control signal (BF control signal) for wireless power transmission beamforming (WPT beamforming) of the array antenna 110 based on the control information and sends it to the wireless processing unit 130. Based on the control information received from the power transmission control unit 140, the communication signal processing unit 120 generates a downlink (DL) transmission signal including a WPT signal and sends it to the wireless processing unit 130.

The power transmission control unit 140 may transfer information received from the base station 20 to the NW communication unit 150, receive control information generated by the external platform 55 based on that information from the NW communication unit 150, and generate a downlink (DL) transmission signal including a WPT signal and a BF control signal based on the control information.

The NW communication unit 150 is connected to the communication network 50 via a wireless communication line, and can communicate with a cloud system, a server, etc. of the external platform 55. The NW communication unit 150 can transmit communication data or information received from the base station 20 to the communication network 50 side, and can also receive communication data or information to be transmitted to the base station 20 from the communication network 50 side. The NW communication unit 150 is a communication unit that communicates with, for example, a feeder station located on the ground.

When communicating with the base station 20 in downlink, the HAPS 10 may perform beamforming (BF) control to form individual beams for each base station 20 or for each target area to which multiple base stations 20 belong, and may perform wireless power transmission for each base station 20 or for each target area. The BF control for each base station 20 or for each target area may be performed by digital BF control in the frequency domain in the communication signal processing unit 120, or may be performed by analog BF control in the wireless processing unit 130.

In FIG. 2, the base station 20 includes an antenna 210, a wireless processing unit 220, a communication signal processing unit 230, a power output unit 240, and a battery 250. The antenna 210 is, for example, composed of a plurality of array antennas having a large number of antenna elements. The wireless processing unit 220 transmits information and transmission signals generated by the communication signal processing unit 230 from the antenna 210 to the HAPS 10, and outputs received signals received from the HAPS 10 via the antenna 210 to the communication signal processing unit 230.

In this embodiment, the wireless processing unit 220 receives a transmission signal for wireless power transmission transmitted from the HAPS 10. The power output unit 240 has, for example, a rectifier, and outputs the power of the received signal that receives the transmission signal for wireless power transmission from the HAPS 10 as received power for charging the battery. The battery 250 can be charged by the received power output from the power output unit 240.

The wireless processing unit 220 may have a function of measuring or acquiring information related to power reception, such as power reception beam information (e.g., information on the direction and width of the power reception beam) and information on the direction of arrival of the WPT radio waves. The power output unit 240 may have a function of measuring the received power. At least one of the information related to power reception, such as power reception beam information, information on the direction of arrival of the WPT radio waves, information on the received power, and control information, can be included in the information to the HAPS 10.

The frequency of the electromagnetic waves of the transmission signal for wireless power transmission transmitted from HAPS 10 to base station 20 is preferably 300 GHz or less, and is more preferably microwaves. In this embodiment, since the transmission signal for wireless power transmission is transmitted from HAPS 10, which is located in the stratosphere, to base station 20 on the ground, electromagnetic waves, particularly microwaves, which are less susceptible to the effects of the atmosphere, are preferred.

Here, when performing wireless power transmission (WPT) from the HAPS 10 to the base station 20, it is difficult to ensure sufficient received power with wireless power transmission from a single HAPS 10. Therefore, in this embodiment, the system obtains power (total power) from a composite signal that combines received signals generated at the base station 20 with transmission signals for wireless power transmission from multiple HAPS 10.

However, if the phases of the multiple received signals of the transmission signals for wireless power transmission transmitted from the multiple HAPS 10 are not aligned, the power transmission efficiency decreases and highly efficient wireless power transmission (WPT) cannot be realized. That is, when the phases of the received signals P _rIn1 and P rIn2 of the base station 20 based on the transmission signals from the multiple HAPS 10 are not aligned as shown in Fig. 3(a), the obtained total power P _rInc is smaller than when they are aligned ( _phase combined) as shown in Fig. 3(b).

In this embodiment, therefore, power is obtained by phase-combining the transmission signals for wireless power transmission sent from multiple HAPS10 so that the phases of the multiple received signals are matched, thereby realizing highly efficient and stable wireless power transmission (WPT).

FIG. 4 is an explanatory diagram showing an example of a method for combining phases so that the phases of a plurality of received signals are matched.
Examples of methods for synthesizing phases so that the phases of multiple received signals are a method for adjusting the phase of a transmission signal for wireless power transmission transmitted from multiple HAPS 10-0, 10-1, ..., 10-n, and a method for adjusting the phase of multiple received signals received by the base station 20. However, the latter phase adjustment method requires equipment changes and setting changes to existing base stations 20 that are not compatible with this system, and when phase adjustment is performed at the power-receiving base station 20, the transmission power is reduced by the amount of power consumption required for the phase adjustment, so the former phase adjustment method is preferable.

Therefore, in this embodiment, as shown in Fig. 4, the former phase adjustment method is adopted, which adjusts the phase of the transmission signal for wireless power transmission transmitted from multiple HAPS 10-0, 10-1, ..., 10-n. That is, input phases Δφ1, Δφ2, ..., Δφn that compensate for the transmission signal path difference between multiple HAPS 10-0, 10-1, ..., 10-n are added to the transmission signals of HAPS 10-1, ..., 10-n other than the reference HAPS 10-0, so that the received signals at the base station 20 are in phase.

A specific phase adjustment method may, for example, adjust the phase of a transmission signal for wireless power transmission transmitted from multiple HAPS 10-0, 10-1, ... 10-n based on feedback information regarding wireless power transmission from the base station 20. For example, multiple HAPS 10-0, 10-1, ... 10-n receive and acquire feedback information regarding wireless power transmission from the base station 20 via a communication UL established between each HAPS and the base station 20. The feedback information may include, for example, power receiving device information regarding power reception at the base station 20 (also referred to as "WPT power receiving information," "WPT terminal information," or "WPT information"). The power receiving device information may include, for example, at least one of the following information: request information requesting wireless power transmission (WPT request), identification information for identifying the base station 20, location information of the base station 20, received power information at the base station 20, power receiving beam information at the base station 20 (e.g., information on the direction, width, etc. of the power receiving beam), information on the direction of arrival of the WPT radio waves at the base station 20, remaining battery charge information in the base station 20, and approval information approving wireless power transmission.

Feedback information (FB information) from the base station 20 received by the array antenna 110 of the HAPS 10 is sent to the communication control unit 115 of the communication relay device 100. The communication control unit 115 generates control information based on the feedback information from the base station 20, and based on the control information, generates a downlink (DL) transmission signal including a wireless power transmission signal (WPT signal) and a control signal (BF control signal) for wireless power transmission beamforming (WPT beamforming) of the array antenna 110 of the HAPS 10, and sends them to the array antenna 110. The array antenna 110 forms a wireless power transmission beam (WPT beam) in the direction of the base station 20 based on the BF control signal, and transmits a downlink (DL) transmission signal (phase-adjusted transmission signal) including a WPT signal via a portion of the wireless resources of the downlink (DL).

The communication control unit 115 of the HAPS 10 may transfer the feedback information received from the base station 20 to a cloud system or server of the external platform 55, receive control information generated by the external platform 55 based on the feedback information, and generate a downlink (DL) transmission signal including a WPT signal and a BF control signal based on the control information.

Furthermore, the feedback information regarding wireless power transmission from the base station 20 may be control information that specifies the phase of the transmission signal for each HAPS 10. In this case, however, the base station 20 executes a process for determining the phase of the transmission signal transmitted from each HAPS 10.

In the phase adjustment method of this embodiment, a pilot signal is transmitted from the base station 20 to multiple HAPS 10-0, 10-1, ... 10-n that are time-synchronized with each other, and the multiple HAPS 10-0, 10-1, ... 10-n determine the transmission timing of the transmission signal based on the reception result of the pilot signal from the base station 20 so that the transmission signals for wireless power transmission arrive at the base station 20 in the same phase.

Specifically, when the pilot signal transmitted from the base station 20 is received by the antenna 110 of each HAPS 10-0, 10-1, ... 10-n, it is sent from the wireless processing unit 130 of each HAPS via the communication signal processing unit 120 to the power transmission control unit 140. The power transmission control unit 140 functions as a synchronization processing unit that performs time synchronization with other HAPSs that share the same power transmission target (base station 20), and performs time synchronization using, for example, PTP (Precision Time Protocol) or the like. In addition, the power transmission control unit 140, together with the wireless processing unit 130 and the antenna 110, etc., constitutes a transmission unit that transmits a transmission signal for wireless power transmission via electromagnetic waves of a predetermined frequency.

The power transmission control unit 140 can determine the difference in transmission signal path length from the reference HAPS10-0 based on the reception time of the pilot signal, and therefore determines input phases Δφ1, Δφ2, ..., Δφn to compensate for this difference, and sends control information for the transmission timing of the transmission signal to which the determined input phases have been added to the wireless processing unit 130. As a result, the wireless processing unit 130 transmits a transmission signal for wireless power transmission (a transmission signal after phase adjustment) from the antenna 110 to the base station 20 with a transmission timing based on that control information.

4, the transmission signals P _In e ^jφ , P _In e ^jφ-Δφ1 , ..., P _In e ^jφ-Δφn input to the antennas 110 of the multiple HAPS 10-0, 10-1, ..., 10-n have the same phase P _r e ^jφ when received by the base station 20. Therefore, as shown in Fig. 3(b), the phase-combined received signal (combined signal) P _rInc is maximized, and highly efficient and stable wireless power transmission (WPT) is realized.

[Embodiment 2]
A wireless power transmission (WPT) system according to another embodiment is a large-space distributed power supply system capable of stably supplying power from a Space Solar Power Satellite (SSPS) to a power receiving device located on the ground, sea, lake, etc., or a power receiving device mounted on a drone located in low-altitude space, by relaying power from the Space Solar Power Satellite (SSPS) through a plurality of power transmitting devices mounted on a plurality of floating bodies (e.g., HAPS, balloons, drones) located in a distributed manner in the stratosphere, etc.

In the following explanation, explanations that overlap with the above-mentioned embodiment 1 will be omitted as appropriate, and the explanation will focus on the points that are different from the above-mentioned embodiment 1.

FIG. 5 is an explanatory diagram showing an example of a schematic configuration of a system according to the second embodiment.
The system of the second embodiment is a system for wireless power transmission (WPT), and includes one or more power transmitting devices mounted on a levitation body located at a predetermined altitude, and a power receiving device that receives a transmission signal transmitted from the power transmitting device and outputs electric power. The one or more power transmitting devices receive a transmission signal for wireless power transmission transmitted from an external device via electromagnetic waves of a first frequency, convert the frequency of the transmission signal for wireless power transmission to a second frequency lower than the first frequency, and transmit the transmission signal for wireless power transmission via the electromagnetic waves of the second frequency.

In this embodiment 2, the floating body is an example of HAPS10 located in the stratosphere, but may be a balloon or a drone, as in the above-mentioned embodiment 1. The receiving device is also an example of a ground base station 20, as in the above-mentioned embodiment 1. However, the transmission signal for wireless power transmission transmitted by HAPS10 in this embodiment 2 to the base station 20 is a transmission signal for wireless power transmission transmitted from an external device, the frequency of which is converted to a lower frequency. Examples of this external device include a power transmission device mounted on another floating body (e.g., another HAPS), a power transmission device located on the ground, on the sea or on a lake, and a power transmission device located at a higher altitude than HAPS10 (e.g., a space solar power generation satellite).

In this embodiment, the external device is an example of a space solar power generation satellite 30 located at an altitude higher than the atmosphere. The space solar power generation satellite 30 is equipped with a solar power generation device, and transmits power output from the solar power generation device to a HAPS 10 in the stratosphere via wireless power transmission, and the power is then transmitted from the HAPS 10 to a ground base station 20, which is a power receiving device, via wireless power transmission.

FIG. 6 is a block diagram showing an example of the main configuration of the HAPS 10 and the base station 20 that constitute the wireless power transmission (WPT) system of the second embodiment.
In addition to the configuration provided in the above-described first embodiment, the HAPS 10 includes an antenna 111 as a receiving unit that receives a transmission signal for wireless power transmission from the space solar power satellite 30 transmitted via electromagnetic waves of a first frequency, and a frequency conversion unit 160 as a conversion unit that converts the frequency of the transmission signal for wireless power transmission received by the antenna 111 to a lower second frequency.

The antenna 111 is, for example, an array antenna having a large number of antenna elements. There may be a single antenna 111 or multiple antennas. The frequency conversion unit 160 provided in the communication relay device 100 of the HAPS 10 converts the frequency (first frequency) of the transmission signal for wireless power transmission received from the space solar power generation satellite 30 via the antenna 111 to a lower second frequency, and sends the frequency-converted transmission signal to the wireless processing unit 130. The wireless processing unit 130 transmits the transmission signal for wireless power transmission sent from the frequency conversion unit 160 from the antenna 110 to the base station 20.

In this embodiment, the frequency of the electromagnetic waves of the transmission signal for wireless power transmission transmitted from the space solar power generation satellite 30 to the HAPS 10 is preferably higher than microwaves, and more preferably millimeter waves, terahertz waves, or light waves. Since the influence of the atmosphere is small between the space solar power generation satellite 30 located at an altitude higher than the atmosphere and the HAPS 10 located in the stratosphere, the electromagnetic waves of the transmission signal for wireless power transmission are preferably high-frequency, particularly millimeter waves, terahertz waves, or light waves. On the other hand, the transmission signal for wireless power transmission transmitted from the HAPS 10 located in the stratosphere to the ground base station 20 is greatly influenced by the atmosphere, so as described above, it is preferable to use electromagnetic waves that are less influenced by the atmosphere, particularly microwaves.

In this embodiment, when transmitting power generated by a space solar power generation satellite 30 to a ground base station 20 wirelessly, wireless power transmission (WPT) is achieved by passing the power through a HAPS 10 located in the stratosphere. That is, in areas with little atmospheric influence, a transmission signal for wireless power transmission is transmitted via higher frequency electromagnetic waves, and in areas with great atmospheric influence, a transmission signal for wireless power transmission is transmitted via lower frequency electromagnetic waves, thereby achieving highly efficient and stable wireless power transmission (WPT).

In addition, it is preferable that the electromagnetic waves of the transmission signal for wireless power transmission transmitted from the space solar power generation satellite 30 to the HAPS 10 are electromagnetic waves in a beam shape formed to have directivity from the space solar power generation satellite 30 toward the HAPS 10. This makes it possible to achieve more efficient wireless power transmission. For example, such electromagnetic waves can be electromagnetic waves whose beam shape is formed by beamforming technology.

In particular, in this embodiment, since the space solar power satellite 30 transmits transmission signals for wireless power transmission to multiple HAPS 10, it is preferable to transmit the multiple transmission signals to each HAPS 10 in a multi-beam manner. This makes it possible to realize more efficient wireless power transmission to each HAPS 10.

In this embodiment, as in the above-described first embodiment, wireless power transmission is performed from multiple HAPS 10 to the base station 20. Therefore, as in the above-described first embodiment, it is preferable to adopt a configuration in which phase synthesis is performed so that the phases of multiple received signals received from the multiple HAPS 10 for wireless power transmission are consistent. However, in this embodiment 2, it is not necessarily required to adopt this configuration.

[Embodiment 3]
A wireless power transmission (WPT) system according to yet another embodiment is a large-space distributed power supply system capable of stably supplying power from a space solar power satellite (SSPS) to a plurality of floating bodies (e.g., HAPS, balloons, drones) located in a distributed manner in the stratosphere or the like.

In the following explanation, explanations that overlap with the above-mentioned embodiments 1 and 2 will be omitted as appropriate, and the explanation will focus on the points that are different from the above-mentioned embodiments 1 and 2.

FIG. 7 is an explanatory diagram showing an example of a schematic configuration of a system according to the third embodiment.
The system of the third embodiment is a system for wireless power transmission (WPT), and includes a space solar power generation satellite 30 located at an altitude higher than the atmosphere, and a plurality of power receiving devices mounted on each of a plurality of floating bodies located at a predetermined altitude lower than the space solar power generation satellite. The space solar power generation satellite 30 transmits a plurality of transmission signals for wireless power transmission in multiple beams via electromagnetic waves of a predetermined frequency. The multiple power receiving devices receive each of the plurality of transmission signals for wireless power transmission transmitted in multiple beams from the space solar power generation satellite 30.

In this embodiment 3, as in the above-mentioned embodiment 2, the space solar power satellite 30 is located at an altitude higher than the atmosphere, is equipped with a solar power generation device, and transmits the power output from the solar power generation device to the HAPS 10 in the stratosphere by wireless power transmission. The receiving device in this embodiment 3 is the HAPS 10, which is a floating body, and the power transmission target of this system is the HAPS 10. Therefore, the HAPS 10 in this embodiment 3 does not have a function (such as the power transmission control unit 140) for wireless power transmission to the ground base station 20, but may have a function for wireless power transmission to the ground base station 20.

In this embodiment 3, the float on which the power receiving device to be transmitted is mounted is an example of a HAPS10 located in the stratosphere, but it may also be a balloon or drone located in the stratosphere, as in the above-mentioned embodiments 1 and 2.

FIG. 8 is a block diagram showing an example of a main configuration of a HAPS 10 constituting a wireless power transmission (WPT) system according to the third embodiment.
The HAPS 10 of the present embodiment 3 differs from the above-mentioned embodiment 2 in that it does not include functions (such as a power transmission control unit 140 and a frequency conversion unit 160) for wirelessly transmitting power to a ground base station 20. The HAPS 10 of the present embodiment 3 also differs from the above-mentioned embodiment 2 in that it includes a wireless processing unit 170, a power output unit 180, and a battery 190.

The wireless processing unit 170 receives the transmission signal for wireless power transmission transmitted from the space solar power satellite 30 via the antenna 111 and sends it to the power output unit 180. The power output unit 180 has, for example, a rectifier, and outputs the power of the received signal that receives the transmission signal for wireless power transmission from the space solar power satellite 30 as received power for charging the battery. The battery 190 can be charged with the received power output from the power output unit 180.

In this embodiment, as in the above-described embodiment 2, the frequency of the electromagnetic waves of the transmission signal for wireless power transmission transmitted from the space solar power generation satellite 30 to the HAPS 10 is preferably higher than microwaves, and more preferably millimeter waves, terahertz waves, or light waves. Since the influence of the atmosphere is small between the space solar power generation satellite 30, which is located at an altitude higher than the atmosphere, and the HAPS 10, which is located in the stratosphere, the electromagnetic waves of the transmission signal for wireless power transmission are preferably high-frequency, particularly millimeter waves, terahertz waves, or light waves.

In addition, in this embodiment, since the space solar power generation satellite 30 transmits transmission signals for wireless power transmission to multiple HAPS 10, the multiple transmission signals are transmitted to each HAPS 10 as multiple beams. This allows for more efficient wireless power transmission to each HAPS 10. Such multiple beams can be realized, for example, by forming the beam shape using beam forming technology.

According to this embodiment, multiple transmission signals for wireless power transmission are transmitted in multiple beams from the space solar power generation satellite 30, and the multiple transmission signals transmitted in multiple beams are received by multiple HAPS 10s located in a dispersed manner in the stratosphere, etc. This makes it possible to realize highly efficient and stable wireless power transmission (WPT).

As described above, according to the first to third embodiments, stable wireless power transmission from a power transmitting device located at a high altitude to a power receiving device is possible.
In addition, the present invention can stabilize wireless power transmission from a transmission device located at a high altitude to a receiving device located on the ground, sea, lake, or in space at a low altitude, thereby contributing to the achievement of Goal 9 of the Sustainable Development Goals (SDGs), which is to "build resilient infrastructure, promote industry, innovation and infrastructure."

The processing steps described in this specification and components of the wireless power transmission system, power transmission system, power receiving system, power transmitting device, power receiving device, levitation body, terminal device, space solar power satellite, etc. can be implemented by various means. For example, these steps and components may be implemented by hardware, firmware, software, or a combination thereof.

For hardware implementation, the processing units and other means used to implement the above steps and components in an entity (e.g., various transmitters, receivers, rectenna devices, wireless communication devices, Node B, terminals, hard disk drive devices, or optical disk drive devices) may be implemented in one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processors (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, electronic devices, other electronic units designed to perform the functions described herein, computers, or combinations thereof.

Also, for firmware and/or software implementations, the means such as processing units used to realize the above components may be implemented with programs (e.g., codes such as procedures, functions, modules, instructions, etc.) that perform the functions described herein. In general, any computer/processor readable medium tangibly embodying firmware and/or software codes may be used to implement the means such as processing units used to realize the above steps and components described herein. For example, the firmware and/or software code may be stored in a memory and executed by a computer or processor, for example in a control device. The memory may be implemented inside the computer or processor or may be implemented externally to the processor. Also, the firmware and/or software code may be stored in a computer or processor readable medium, such as, for example, a random access memory (RAM), a read-only memory (ROM), a non-volatile random access memory (NVRAM), a programmable read-only memory (PROM), an electrically erasable PROM (EEPROM), a flash memory, a floppy disk, a compact disk (CD), a digital versatile disk (DVD), a magnetic or optical data storage device, etc. The code may be executed by one or more computers or processors and may cause the computers or processors to perform certain aspects of the functionality described herein.

The medium may be a non-transitory recording medium. The program code may be in any format as long as it can be read and executed by a computer, processor, or other device or machine, and the format is not limited to a specific format. For example, the program code may be any of source code, object code, and binary code, or may be a mixture of two or more of these codes.

Moreover, the description of the embodiments disclosed herein is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the present disclosure. Thus, the present disclosure is not intended to be limited to the examples and designs described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

10: H.A.P.S.
20: Base station 30: Space solar power satellite 50: Communication network 55: External platform 100: Communication relay device 110, 111: Antenna 115: Communication control unit 120: Communication signal processing unit 130: Wireless processing unit 140: Power transmission control unit 150: NW communication unit 160: Frequency conversion unit 170: Wireless processing unit 180: Power output unit 190: Battery 210: Antenna 220: Wireless processing unit 230: Communication signal processing unit 240: Power output unit 250: Battery

Claims (24)

A system for wireless power transmission,
A plurality of power transmitting devices are mounted on a levitation body located at a predetermined altitude and transmit a transmission signal for wireless power transmission via an electromagnetic wave of a predetermined frequency;
one or more power receiving devices that receive the plurality of transmission signals transmitted from the plurality of power transmitting devices and output power by phase-combining a plurality of reception signals;
A system comprising: 2. The system of claim 1,
The power receiving device transmits a pilot signal to the plurality of power transmitting devices,
The plurality of power transmitting devices are
They are time-synchronized with each other,
determining a transmission timing of the transmission signals for wireless power transmission based on a reception result of the pilot signal received from the power receiving device so that the transmission signals for wireless power transmission transmitted from the plurality of power transmitting devices arrive at the power receiving device in the same phase;
A system characterized by: 2. The system of claim 1,
The frequency of the electromagnetic wave is 300 GHz or less.
A system characterized by: In the system of claim 3,
The electromagnetic wave is a microwave.
A system characterized by: In the system of claim 3,
The electromagnetic wave is a beam-shaped electromagnetic wave formed to have directivity from the power transmitting device to the power receiving device.
A system characterized by: 2. The system of claim 1,
The float is a HAPS, a balloon or a drone located in the stratosphere;
A system characterized by: 2. The system of claim 1,
The power receiving device is located on land, sea or lake, or in a space at a low altitude lower than the power transmitting device.
A system characterized by: A wireless power transmission device,
It is mounted on a floating body located at a predetermined altitude,
A transmitter that transmits a transmission signal for wireless power transmission via electromagnetic waves of a predetermined frequency.
A power transmitting device comprising: The power transmitting device according to claim 8,
A synchronization processing unit that performs time synchronization with another power transmission device having a common power transmission target,
the transmitting unit determines a transmission timing of the transmission signals for wireless power transmission based on a reception result of a pilot signal received from the power receiving device so that the transmission signals for wireless power transmission transmitted from the plurality of power transmitting devices arrive at the power receiving device in the same phase.
A power transmitting device comprising: A wireless power transmission system including a plurality of power transmission devices,
Each of the plurality of power transmission devices is the power transmission device according to claim 8.
A power transmission system comprising: A wireless power transmission receiving device,
a receiving unit that receives a transmission signal for wireless power transmission via an electromagnetic wave of a predetermined frequency from a plurality of power transmitting devices respectively mounted on a levitation body located at a predetermined altitude;
a combining unit that combines a plurality of received signals that have received the plurality of transmission signals in phase;
A power receiving device comprising: The power receiving device according to claim 11,
A transmitter that transmits a pilot signal to the plurality of power transmitting devices.
A power receiving device comprising: A system for wireless power transmission,
a power transmitting device that is mounted on a levitation body located at a predetermined altitude, receives a transmission signal for wireless power transmission from an external device via electromagnetic waves of a first frequency, converts the frequency of the transmission signal for wireless power transmission to a second frequency that is lower than the first frequency, and transmits the transmission signal for wireless power transmission via electromagnetic waves of the second frequency;
a power receiving device that receives the transmission signal transmitted from the power transmitting device and outputs power;
A system comprising: 14. The system of claim 13,
the electromagnetic wave of the first frequency is a millimeter wave, a terahertz wave, or a light wave,
The electromagnetic wave of the second frequency is a microwave.
A system characterized by: 14. The system of claim 13,
The electromagnetic wave of the first frequency is a beam-shaped electromagnetic wave formed to have directivity from an external device to the power transmitting device.
The electromagnetic wave of the second frequency is a beam-shaped electromagnetic wave formed to have directivity from the power transmitting device to the power receiving device.
A system characterized by: 14. The system of claim 13,
the external device is a space solar power satellite located in space outside the atmosphere;
The float is a HAPS, a balloon or a drone located in the stratosphere;
A system characterized by: 14. The system of claim 13,
The power receiving device is located on land, sea or lake, or in a space at a low altitude lower than the power transmitting device.
A system characterized by: A wireless power transmission device,
It is mounted on a floating body located at a predetermined altitude,
a receiving unit that receives a transmission signal for wireless power transmission via an electromagnetic wave of a first frequency;
a conversion unit that converts a frequency of the transmission signal for wireless power transmission into a second frequency that is lower than the first frequency;
a transmitting unit that transmits a transmission signal for wireless power transmission via an electromagnetic wave of the second frequency;
A power transmitting device comprising: A system for wireless power transmission,
a space solar power generation satellite that is located at an altitude higher than the atmosphere and transmits a plurality of transmission signals for wireless power transmission in multiple beams via electromagnetic waves of a predetermined frequency;
a plurality of power receiving devices mounted on a plurality of floating bodies located at a predetermined altitude lower than the space solar power generation satellite, the plurality of power receiving devices receiving the plurality of transmission signals for wireless power transmission transmitted by multi-beams from the space solar power generation satellite;
A system comprising: 20. The system of claim 19,
The electromagnetic wave is a millimeter wave, a terahertz wave, or a light wave.
A system characterized by: 20. The system of claim 19,
The float is a HAPS, a balloon or a drone located in the stratosphere;
A system characterized by: A space solar power satellite,
Located at an altitude higher than the atmosphere,
a transmitter that transmits a plurality of transmission signals for wireless power transmission in a multi-beam manner via electromagnetic waves of a predetermined frequency to a plurality of power receiving devices mounted on a plurality of floating bodies located at a predetermined altitude lower than the space solar power generation satellite;
A space solar power satellite. A wireless power transmission receiving device,
The satellite is mounted on each of a plurality of floating bodies located at a predetermined altitude lower than the space solar power satellite,
a receiving unit that receives a transmission signal for wireless power transmission transmitted from the space solar power generation satellite via an electromagnetic wave of a predetermined frequency;
A power receiving device comprising: A wireless power transmission power receiving system including a plurality of power receiving devices,
Each of the plurality of power receiving devices is a power receiving device according to claim 23.
A power receiving system comprising:

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