JP7283689B2 - wireless power transmission system - Google Patents

Description

The present invention relates to wireless power transmission systems.

In recent years, the number of IoT devices such as sensors and devices with power constraints such as unmanned aerial vehicles (UAVs) such as drones has been increasing. These devices are expected to play an active role in various situations such as factories and disasters. Problems include interference with equipment. As a solution to this problem, application of WPT (wireless power transfer) technology can be considered. Among wireless power transmissions, microwave power transmission is considered promising as it enables long-distance transmission necessary for power supply to IoT devices and UAVs.

Wireless Power Transfer (or Wireless Power Transmission: WPT) includes transmission technology as well as wireless power supply itself. Wireless power transmission is roughly classified into the following three types.
(1) A power transmission method using electromagnetic induction. In this power transmission method, power is transmitted by utilizing an electromotive force generated by changing the magnetic flux density passing through the coil.
(2) A power transmission method using magnetic resonance. In this power transmission method, power is supplied through magnetic energy by LC resonance of the coils on the power transmission side and the power reception side at the same magnetic frequency.
(3) A power transmission method using electromagnetic waves. In this power transmission method, power is transmitted by rectifying electromagnetic waves received using an antenna and converting them into direct current. In the transmission method using electromagnetic waves, the microwave band (GHz band) or a higher frequency band is often used because the transmission efficiency is relatively better than that of the antenna theory. The power transmission method in this case is particularly called a microwave space transmission method. For wireless power transmission using microwaves, for example, Patent Document 1 is available.

JP 2015-116029

In wireless power transmission, the requirements that generally need to be considered include increasing the capacity of wireless power supply, extending the distance, improving efficiency, improving reliability, avoiding damage to the human body and interference with other wireless devices, etc. Considering a network that passes through multiple repeaters (nodes), it is necessary to improve efficiency by reducing the power consumption of the entire network, and to improve reliability by reducing damage and interference to the human body and other equipment. It is necessary to optimize the feed path and the directivity of the antenna. In wireless power transmission using microwaves, the power density decreases in proportion to the square of the power supply distance when moving away from the source of transmission. is an issue.

The present invention uses a multi-hop relay that adds a repeater (node) between a power transmitter and a power receiver to relay and transmit power. According to the present invention, by transmitting power using multi-hop relays, the distance between each node of the power transmitter, the power receiver, and the repeater in the transmission system is shortened, and the influence of attenuation due to the transmission distance is reduced. According to the present invention, compared to when power is directly supplied between the power transmitter and the power receiver, power is transmitted via a repeater using a multi-hop relay. long-distance power supply efficiency increases.

A power transmitter is a node that transmits power, a power receiver is a node that receives the transmitted power, and a repeater is a node that transfers power between the power transmitter and the power receiver. A power transmitter may be referred to as a power transmitter instead of a power transmitter in the meaning of supplying electric power, but in the present invention, the term is used for a power transmitter paired with a power receiver.

In a multi-hop relay, when there are multiple relay node candidates, multiple feed paths (routes) can be set. The present invention can select a power supply route that maximizes the end-to-end power supply efficiency between the power transmitter and the power receiver from among these power supply routes. Also, the present invention may select routing that minimizes interference to the human body and other wireless devices. By providing a repeater, the present invention can be used not only for power transmission with a long transmission distance, but also for normal line of sight (LOS) environments, as well as non-line of sight (Non Line of Sight: NLOS) environments such as inside buildings. Power feeding that avoids interference is also possible. Note that the repeater may have a battery or a power supply and have an amplifying function. In this case, the repeater also functions as a power transmitter.

The present invention derives the optimum number of repeaters that maximizes power supply and minimizes interference with the human body and other wireless devices in a multi-hop relay.

The present invention solves the problem of power reduction during power transmission in a multi-hop relay by providing a power amplification function (ET function) to a repeater and performing relay amplification to amplify power during power transmission, Compensate for power drop during transmission.

Furthermore, during power transmission between nodes, if the reflected waves from the ground, artificial objects such as buildings or walls, etc. enter the next node, the phase shift between the direct wave and the reflected wave will occur. There is a problem that the amount of power supply is reduced due to the influence of The present invention addresses the problem caused by this phase shift by changing the frequency of power transmission from the node to improve the power supply amount.

The present invention is a wireless power transmission system that wirelessly transmits power using microwaves,
(a) a physical layer of the first layer for performing power transmission between nodes by multi-hop relay;
(b) a second layer MAC (Media Access Control) layer for controlling power transmission and reception between multiple nodes;
(c) a layer 3 network layer that optimizes the routing of the network of nodes;

In the wireless power transmission system, in power transmission performed through a plurality of nodes constituting a physical layer of the first layer, power transmission and reception between each of the plurality of nodes is controlled by the MAC layer of the second layer, and a plurality of nodes configured by the plurality of nodes are controlled. The optimum power supply route is selected from the network using the power supply efficiency as an evaluation index.

The selection of the power supply path is
(1) Active route selection (active routing) for selecting relay nodes in order to avoid failures due to intrusion and interference to people and communication devices other than repeaters, in addition to repeaters.
(2) Including passive route selection (passive routing) in which reflectors such as the ground and artificial objects are part of the route, these active route selection (active routing) and passive route selection (passive routing) ), the optimum feed path is selected by selecting the nodes and reflectors that make up the network and maximizing the feed efficiency.
(3) Place additional repeaters (nodes) in order to maximize the efficiency of power supply to the target final power receiving power in the power supply path that is optimally routed between existing repeaters (nodes). select the best placement for

[Physical layer]
The wireless power transmission system of the present invention includes a physical layer of the first layer for performing power transmission between nodes by multi-hop relays.

A node in the physical layer is a power transmitter, a power receiver, and a repeater that transmits and receives power between each node. Power is transmitted from the power transmitter to the power receiver via the repeater by multi-hop relay.

(repeater)
A repeater is one configuration that reduces power reduction during power transmission by relaying transmitted power. , and an appropriate inter-repeater distance are obtained.

・Number of repeaters:
The optimum number of repeaters is obtained by maximizing the amount of power supply based on the relationship between the power supply amount between power transmission and reception, the number of repeaters, distance attenuation, and repeater loss.

・Distance between repeaters:
As for the distance between repeaters, the optimum repeater distance is obtained by the distance that maximizes the amount of power supply based on the relationship between the power supply amount between power transmission and reception, the number of repeaters, distance attenuation, and repeater loss.

・Repeater power amplification function:
By providing the repeater with a function of power-amplifying received power and transmitting the power-amplified power, power reduction during power transmission can be reduced. As a result, the total transmission power is reduced with respect to the power requested by the receiving power. Here, the total transmitted power is the power obtained by adding the transmitted power of the power transmitter and the power required for power amplification of the repeater.

In a configuration in which a repeater has a function of amplifying received power, the number of repeaters is the number that minimizes the total amount of power amplification of the repeaters with respect to the amount of power required by the power receiver. .

・Frequency change:
Between the nodes of the power transmitter and the repeater, in addition to the direct wave mainly due to spatial propagation, there are cases where the reflected wave arrives after being reflected by the ground due to the propagation environment. A phase shift may occur between the two waves, the direct wave and the reflected wave, depending on the distance between the nodes, and this phase shift may affect the received power on the power receiving terminal side, leading to a decrease in power. In order to reduce the influence of this reflected wave, the power transmission frequency for power transmission at the nodes of the transmitter and repeater is changed to a wireless propagation space such as a direct wave that reaches directly between nodes, a reflected wave that arrives after being reflected by the ground, and a phase shift. The frequency is selected from frequencies suitable for the frequency propagation characteristics of

By selecting the frequency between each node based on the distance between each node, the power transmitter can perform power transmission at the optimum frequency between each node.

In each node of the physical layer of the first layer, in cooperation with the MAC layer of the second layer for controlling power transmission and reception between multiple nodes, microwave phase adjustment, beam width adjustment, and multi-beam formation I do.

・Phase adjustment:
Multipoint-to-one power transmission, in which power is transmitted from multiple sources to a single receiving end, reduces power cancellation due to phase shift at the receiving end. As a configuration for reducing this power reduction, time synchronization and phase shift compensation are performed between transmission sources.

Time synchronization: A power receiver receives power directly from a plurality of power transmitters or receives power via a plurality of repeaters, and the power transmitters or the plurality of repeaters transmit power by time synchronization.

Phase shift compensation: In the power transmission from multiple nodes to the receiving power, the node calculates the distance between the receiving power and each node based on the azimuth angle of each node from the receiving power, and the phase shift between the nodes based on the distance. A quantity is determined and compensated for transmission phase shift based on the phase shift.

・Optimal beam width:
The received power decreases due to the phase shift due to the angle error of the azimuth angle and/or the elevation angle between the main lobes of the antenna beams of the receiving end and the transmitting source.

The power transmitter optimizes the beam width of the power transmission antenna of the power transmitter by the gain of the power transmission antenna of the power transmitter determined based on the azimuth (Δθ) and elevation angle (Δφ) formed by the power transmitter and the repeater or receiver. do.

- Optimal beam shape In one-to-multipoint power transmission, in which power is transmitted from one power source to multiple power receiving ends, power is supplied to multiple power receiving nodes by antenna multi-beams. A power transmitter forms an optimum beam for transmitting power to a plurality of receivers by multi-beam.
Antenna directivity The power transmitter designs the antenna directivity so that the beam is narrowed down in the radio wave radiation direction (beamforming) and the beam is not radiated in directions other than the radio wave radiation direction (null steering).
・Directivity of the antenna attached to the vibrating power supply target The power transmitter is optimal for the receiver (power supply target) that moves or swings like a drone by narrowing the beam emitted from the power transmitter antenna. design a directivity. This directivity optimization improves power receiving efficiency by widening the beam width according to the vibration dispersion in which the position is dispersed due to the vibration of the power receiver (power supply target).
・Directivity of antennas attached to multiple transmitters or multiple receivers Design the spread of the directivity of the antenna that feeds the

[Network layer]
The wireless power transmission system of the present invention comprises a third layer network layer that optimizes the power feeding path (route) of a network consisting of multiple nodes. The network layer selects the optimal power feeding route that maximizes the power feeding efficiency in the multi-hop relay.

The network layer uses a weighted graph in which the weight of the route corresponds to the power transmission efficiency between adjacent repeaters in a route with a pair of transmitter and receiver and multiple repeaters as nodes, and the power supply efficiency is optimized as an evaluation index. Select a power supply lead. The power supply efficiency is defined as the sum of the weights of the routes between the power transmitter and the power receiver by the Dijkstra method, and the route with the maximum power supply efficiency is set as the power supply route of the optimized network.

In the physical layer, (1) active routing and (2) passive routing select nodes and reflectors that make up the network to maximize power supply efficiency. Therefore, the optimum power supply path is selected. The network layer uses the weights of the paths in the weighted graph to select the optimal powering path in cooperation with the powering efficiency maximizing path selection of the physical layer.

For example, the weight is set to a value greater than or equal to 1 for active routing, and the weight is set to less than 1 for passive routing. In the case of passive route selection (passive routing weights), weighting including weight 1 may be used when reflection is performed without attenuation.
In route selection and power supply route selection, in addition to selection based on power supply efficiency and transmission efficiency, selection based on avoidance of interference with the human body and wireless devices is performed. The selection of routes and the selection of power supply routes based on these two selection criteria can be handled in a unified manner by weighting. For example, in a selection based on avoiding interference with the human body or wireless devices, weighting of routes with risk of interference is set to zero or a negative value. It is possible to select a route that takes into account the criteria of power supply efficiency and transmission efficiency and the criteria of interference avoidance at the same time.

Also, in obtaining the power transmission efficiency between repeaters,
(1) The receiver broadcasts a power supply request packet (EREG packet) containing position information,
(2) the repeater reloadcasts the power supply request packet (EREG packet);
(3) The power transmitter obtains the inter-node distance based on the position information included in the received power supply request packet (EREG packet), and acquires the power transmission efficiency based on the inter-node distance.
(4) The power transmitter supplies power in a packet-shaped power packet to the power receiver requesting power supply by the power supply request packet (EREG packet).

(Wireless power transmission and wireless information transmission)
The network layer, together with the physical layer and the MAC layer, can support simultaneous transmission of wireless power transmission for wirelessly transmitting power and wireless information transmission for wirelessly transmitting information.
The present invention uses a power packet that transmits power and an information packet for information communication that communicates position and phase information and the timing of transmitting and receiving the packet, and the access control protocol of the MAC layer handles both the power packet and the information packet. performs wireless power transmission and wireless information transmission.

At the network layer,
(1) In wireless power transmission, in a route having a pair of transmitter/receiver and a plurality of repeaters as nodes, transmission is performed by the Dijkstra method in a weighted graph in which the weight of the route corresponds to the power transmission efficiency between adjacent repeaters. The power supply efficiency is defined as the sum of the weights of the power transmission paths between the electric machine and the receiving machine.
(2) In wireless information transmission, in a route having a pair of transmitter/receiver and a plurality of repeaters as nodes, a weighted graph in which the weight of the route corresponds to the signal-to-noise ratio (S/N ratio) between adjacent repeaters. , the sum of the weights of the information transmission paths between the power transmitter and the power receiver is defined as the path signal-to-noise ratio by Dijkstra's method.
(3) The route that maximizes the sum of the weighted additions of the power feeding efficiency and the route signal-to-noise ratio is taken as the power feeding route of the optimized network.
(4) In the selection based on avoidance of interference with the human body and wireless devices, by setting the weight according to the degree of risk, such as setting the weight of the route with the danger of interference to zero or a negative value. , routing is selected by taking into consideration the criteria of power supply efficiency and transmission efficiency and the criteria of interference avoidance at the same time.
As a result, the optimum path can be selected from both the power transmission path for wireless power transmission and the information transmission path for wireless information transmission.

[MAC layer]
The wireless power transmission system of the present invention includes a MAC layer of the second layer for controlling power transmission and reception between multiple nodes. Power transmission/reception between multiple nodes includes power transmission/reception from multiple power transmission nodes (power supply nodes) to one power reception node, and the MAC layer includes multiple protocols.
The protocol of the MAC layer performs accelerator control for avoiding collision between power packets and information packets for wireless information transmission using the same frequency and space. Under the current Radio Law, the allowable upper limit of EIRP, which is equivalently represented by the received power on the receiving side receiving interference, is a technical condition of the Radio Law. radiated power from INDUSTRIAL APPLICABILITY The present invention can satisfy the technical conditions under the Radio Law by standardizing the MAC protocol for wireless power transmission and the MAC protocol for wireless information transmission.

(1) The MAC layer has a protocol for packetizing power transmission intervals, detecting and avoiding collisions of power transmission packets (power packets) from multiple nodes by carrier sense, and retransmitting the packets.
(2) The MAC layer has a protocol that allocates time slots for transmission packets (information packets) from multiple nodes in a time division manner.
(3) The MAC layer packetizes the power transmission interval, detects and avoids collisions of power transmission packets (power packets) from multiple nodes by carrier sense, and retransmits them, and time slots for transmission packets from multiple nodes in time division. , both protocols are provided.
(4) The MAC layer has a protocol for phase-combining transmission packets (power packets) from multiple nodes and maximizing received power.
(5) The MAC layer has a CDMA protocol for simultaneously receiving power from a plurality of power transmitting nodes (power feeding nodes) at one power receiving node using orthogonal or pseudo-orthogonal codes.
In the code orthogonality of the protocol of the CDMA system, a plurality of mutually orthogonal codes are used as IDs (recognition identifiers) of transmission nodes, so that power packets (feeding packets) overlap at the same time and at the same frequency. can be separated and received.
The TDMA protocol can avoid collisions of power packets for power transmission (power supply packets) by not overlapping orthogonally on the time axis even in the same space at the same frequency.
The FDAM protocol can be separated in time and space by transmitting power packets (feeding packets) of different frequencies from a plurality of power transmitting nodes due to orthogonality on the frequency axis.
The SDMA protocol separates multiple transmission power packets (power supply packets) sent at the same time with the same code at the same frequency due to antenna directivity and orthogonality on the power supply path (route), even if they overlap. can do.
These CDMA, TDMA, FDAM, and SDMA protocols can be applied in arbitrary combinations.

The MAC layer of the third layer cooperates with the physical layer of the first layer to perform microwave phase adjustment, beam width adjustment, and multi-beam formation.

[Wireless power/information transmission system]
The present invention comprises a wireless power/information transmission system that wirelessly transmits power and information simultaneously. Wireless power and information transmission system
(1) 1st layer physical layer for performing power transmission and information transmission between nodes by multi-hop relay (2) 2nd layer MAC layer for controlling power transmission and reception between multiple nodes (3 ) a third network layer that optimizes the power and information transmission paths of a network of nodes,
(4) Wireless power transmission wirelessly transmits power using microwaves,
(5) wireless power transmission optimizes the power supply path for power transmission based on power supply efficiency;
(6) Wireless information transmission optimizes the transmission path for information transmission based on signal-to-noise ratio (S/N ratio) and/or channel capacity.

Multiple forms of simultaneous wireless transmission of power and information can be applied.
(first form)
A first mode of simultaneous wireless transmission of power and information is a mode in which power is transmitted by the amplitude of a microwave carrier wave and information is transmitted by the phase of the microwave, whereby power and information are simultaneously multiplexed and transmitted. . In the microwave band, the carrier wave may be a single wavelength or multiple wavelengths. For example, there are 2.4 GHz, 5.7 GHz, 24 GHz, etc. as multiple wavelengths. The first form corresponds to the FDMA protocol in the MAC layer.

(Second form)
A second form of simultaneous wireless transmission of power and information is a form of packetizing the power that supplies the power transmission and on/off modulating the packetized power packets. Power is transmitted in units of packets by power packets, and information is transmitted by time intervals in time-divided power packets. This enables simultaneous multiplex transmission of power and information. The second form corresponds to a TDMA protocol, particularly ON/OFF keying modulation, in the MAC layer.

As described above, according to the present invention, it is possible to improve the power transmission efficiency of long-distance power supply in wireless power transmission.

1 is a diagram for explaining an overview of a wireless power transmission system of the present invention; FIG. 1 is a diagram schematically showing a node and a network composed of a plurality of nodes; FIG. It is a figure which shows the structure of a rectenna. FIG. 3 is a diagram showing the relationship of power conversion efficiency (PCE) to frequency; FIG. 2 shows a system model of frequency selection; It is a figure which shows a power transmission antenna model. FIG. 4 is a diagram showing frequency characteristics of power transmission efficiency in free space propagation; It is a figure which shows the frequency characteristic of power conversion efficiency (PCE). 4 is a flowchart for explaining the flow of frequency selection of a power transmitter; FIG. 10 is a diagram showing a two-pulse propagation model; FIG. 4 is a diagram showing frequency characteristics of power supply efficiency; FIG. 3 is a diagram comparing average power supply efficiency between a wireless power transmission system by frequency selection and a system using a single frequency; FIG. 4 is a diagram showing a power feeding model using a multi-hop relay; FIG. 4 is a diagram showing the amount of power supplied by a multi-hop relay; FIG. 4 is a diagram showing a power feeding model using a multi-hop relay; It is a block diagram of a Distribution and Forward method. It is a block diagram of a Rectification and Forward method. FIG. 4 is a diagram showing an example of the relationship between the number of hops and the difference of efficiency; FIG. 2 is a diagram showing an overview of positioning errors of a movable repeater node (power receiving terminal) such as a drone; FIG. 4 is a diagram showing positioning errors; FIG. 10 is a diagram showing evaluation of end-to-end power supply efficiency with respect to maximum angular deviation; FIG. 4 is a diagram showing evaluation of end-to-end power supply efficiency with respect to frequency; FIG. 4 is a diagram showing the relationship between frequency and end-to-end power supply efficiency; FIG. 4 is a diagram showing the total amount of amplification in each repeater for sending the required amount of power; FIG. 10 is a diagram for comparing each feed amount when power is amplified by a repeater and when power is amplified by a power transmitter; FIG. 4 is a diagram for comparing power supply amounts when power is amplified by a repeater and when power is amplified by a power transmitter; It is a figure which shows the 2-wave model of a direct wave and a reflected wave which considered the reflected wave. It is a figure which shows the result normalized by the area which a phase matches in the superposition of two waves. 4 is a flow chart for explaining a procedure for deriving an optimum frequency; FIG. 10 is a diagram showing the amount of power supplied when the frequency is changed; FIG. 10 is a diagram showing the optimum number of hops with respect to the total distance when the frequency is changed; FIG. 10 is a diagram showing an example of an indicated frequency simulation for inter-node distance (receiving terminal distance); FIG. 2 is a diagram showing a schematic configuration of wireless power transmission using a multi-hop relay; FIG. 2 is a diagram for explaining an environment of a power feeding route; FIG. FIG. 4 is a diagram for explaining a weighted graph; FIG. FIG. 4 is a diagram for explaining communication of position information in a multi-hop relay for feeding; FIG. 4 is a diagram for explaining a procedure on the side of a power transmitter for transmitting position information; FIG. 4 is a diagram for explaining a procedure of a repeater that transmits position information; FIG. 4 is a diagram for explaining a procedure for transmitting position information; FIG. FIG. 4 is a diagram for explaining a procedure on the side of a power receiver for transmitting position information; FIG. 10 is a diagram showing a case where the total power transmission distance is 10 m as a result of simulating the number of nodes of end-to-end power supply efficiency and the average power supply efficiency; FIG. 10 is a diagram showing the results of a simulation of the number of nodes of end-to-end power supply efficiency and the average power supply efficiency when the total power transmission distance is 20 m; FIG. 10 is a diagram showing the results of a simulation of the number of nodes of end-to-end power supply efficiency and the average power supply efficiency when the total power transmission distance is 30 m; FIG. 10 is a diagram showing the results of a simulation of the number of nodes of end-to-end power supply efficiency and the average power supply efficiency when the total power transmission distance is 40 m; FIG. 10 is a diagram showing power consumption by communication with respect to the number of nodes; 1 is a diagram showing a schematic configuration for receiving power from a plurality of power transmitters; FIG. FIG. 4 is a diagram showing power transmission from a plurality of antennas when power is supplied from a plurality of power transmitters; FIG. 4 is a diagram showing the positional relationship between a node (power receiving terminal) Rx and antennas Tx1 and Tx2; FIG. 4 is a diagram showing a state in which there is an error between the direction of the drone as seen from the antenna and the direction of the main lobe of the antenna; FIG. 10 is a diagram showing a simulation example of optimum beam width; FIG. 4 is a diagram showing a variation model of a drone; 4 is a flow chart of beamforming; FIG. 10 is a diagram showing simulation of beam width when transmission distance is changed; FIG. 10 is a diagram showing the relationship between the optimum beam width considering the angle error and the amount of movement of the drone; FIG. 10 is a diagram showing a moving state associated with attitude control against wind when the drone is in a stationary state; FIG. 10 is a diagram showing power feeding efficiency when a drone that is about to stand still moves due to wind or attitude control; FIG. 10 is a diagram showing the movement state of the drone depending on the delay time; FIG. 10 is a diagram showing power supply efficiency with respect to the average amount of movement of the drone;

The wireless power transmission system of the present invention includes a first layer physical layer for performing power transmission between nodes by multi-hop relays, a second layer MAC layer for controlling power transmission and reception between multiple nodes, and multiple nodes and a network layer of layer 3 that optimizes the feed path of the network consisting of: According to the layered wireless power transmission system of the present invention, in power transmission performed through a plurality of nodes constituting the physical layer of the first layer, the MAC layer of the second layer controls power transmission and reception between each of the plurality of nodes. The optimal power supply route is selected from among multiple networks consisting of nodes using power supply efficiency as an evaluation index, and wireless power transmission using microwaves is performed between each node using multi-hop relays.

FIG. 1 is a diagram for explaining the outline of the wireless power transmission system of the present invention. As shown in FIG. 1(a), the wireless power transmission system 10 is composed of a plurality of layers including a physical layer 11 as the first layer, a MAC layer as the second layer, and a network layer as the third layer.

The physical layer 11 of the first layer is composed of a plurality of nodes, and is a layer that performs power transmission by relaying between nodes by multi-hop relay relays. A plurality of nodes relay power to the next node in the power supply path between the power transmitter, which is the power supply source that supplies power, the power receiver, which is the recipient of the power supply, and the power supply path between the power transmitter and the power receiver. Equipped with a repeater.

The MAC layer 12 of the second layer is a layer that controls power transmission and reception between multiple nodes according to a predetermined protocol.

The network layer 13, which is the third layer, is a layer for optimizing a power supply route of a network consisting of a plurality of nodes using power supply efficiency as an evaluation index.

Each layer cooperates to control power transmission between multiple nodes of the physical layer 11 of the first layer by the MAC layer of the second layer, and to control multiple nodes of the network composed of multiple nodes of the physical layer 11 of the first layer. From among the power supply routes, the network layer 13 of the third layer selects the optimum power supply route using the power supply efficiency as an evaluation index, and wireless power transmission by microwaves between nodes is performed by multi-hop relays.

An application layer 14 that is a fourth layer that ensures security may be provided above the network layer 13 that is the third layer.

FIG. 2 schematically shows a node and a network of nodes. Here, the network 4 is composed of a plurality of repeaters 3 as nodes. Note that although FIG. 2 shows an example in which the network 4 is composed only of a plurality of repeaters 3 , the network 4 may include the power transmitter 1 , the power receiver 2 , and the repeaters 3 .

The MAC layer 12 of the second layer controls power transfer between each node of the physical layer 11 of the first layer according to the protocol, and the network layer 13 of the third layer is formed by the network of the physical layer 11 of the first layer. An optimum power supply route is selected from a plurality of power supply routes using the power supply efficiency as an evaluation index.

(Simultaneous wireless transmission of power and information)
FIG. 1(b) shows the relationship between wireless power transmission 100 and wireless information transmission 200 of the present invention. The wireless power transmission 100 and the wireless information transmission 200 of the present invention have a similar hierarchical structure, thereby making it possible to wirelessly transmit both power and information at the same time.

The wireless power transmission 100 includes a multi-hop relay layer 101 as a configuration corresponding to the physical layer 11 of the first layer, the MAC layer 12 of the second layer, the network layer 13 of the third layer, and the application layer 14 of the fourth layer. , a wireless power supply control layer 102 , an optimum power supply path layer 103 , and a security layer 104 .

On the other hand, the radio information transmission 200 includes a modulation/coding layer 201 as a configuration corresponding to the physical layer 11 of the first layer, the MAC layer of the second layer, the network layer of the third layer, and the application layer 14 of the fourth layer. , a communication control protocol layer 202 , an information routing layer 203 , and a security layer 204 . In wireless power transmission 100 and wireless information transmission 200, wireless power transmission 100 has power supply efficiency 105 as an evaluation index 15 for evaluating power transmission efficiency, and wireless information transmission 200 has S as an evaluation index 15 for evaluating information transmission efficiency. It has a /N ratio 205a and a channel capacity 205b.

By making wireless power transmission 100 and wireless information transmission 200 have a similar hierarchical structure, a network of similar nodes is used, and power transmission control and information transmission control are performed by the physical layer 11 of the first layer and the MAC of the second layer. layer, and the network layer of the third layer to avoid interference.

In addition, in a plurality of paths formed by a plurality of nodes, the optimum path is determined by considering the power supply efficiency 105 of the wireless power transmission 100, the S/N ratio 205a of the wireless information transmission 200, and the power supply efficiency 105 of the communication channel capacity 205b. to select.

(Wireless power/information transmission system)
The wireless power/information transmission system for simultaneously wirelessly transmitting power and information according to the present invention includes:
(1) 1st layer physical layer for power transmission and information transmission between nodes by multi-hop relay (2) 2nd layer MAC layer for controlling power transmission/reception between multiple nodes (3) ) A third network layer that optimizes the power and information transmission paths of the network of nodes.

The wireless power/information transmission system consists of the following in each layer: (a) Wireless power transmission uses microwaves to wirelessly transmit power;
(b) wireless power transmission optimizes the power transmission feed path based on power feed efficiency,
(c) Wireless information transmission optimizes the transmission path for information transmission based on signal-to-noise ratio (S/N ratio) and/or channel capacity.
In wireless power/information transmission systems, route selection can be optimized using power supply efficiency and transmission efficiency as evaluation criteria, as well as optimization using interference levels to human bodies and wireless devices as evaluation criteria. Examples of wireless devices include existing wireless communication devices, wireless information transmission devices, other wireless power transmission devices, devices affected by radio wave interference, and wireless medical devices such as wireless capsule endoscopes for small and large intestines. There are medical devices that transmit and receive

Multiple forms of simultaneous wireless transmission of power and information can be applied.
(First form of simultaneous wireless transmission)
A first mode of simultaneous wireless transmission of power and information is a mode in which power is transmitted by the amplitude of a microwave carrier wave and information is transmitted by the phase of the microwave, whereby power and information are simultaneously multiplexed and transmitted. . In the microwave band, the carrier wave may be a single wavelength or multiple wavelengths. For example, there are 2.4 GHz, 5.7 GHz, 24 GHz, etc. as multiple wavelengths.

(Second form of simultaneous wireless transmission)
A second form of simultaneous wireless transmission of power and information is a form of packetizing the power that supplies power transmission and ON/OFF-modulating the packetized power packets, which is ON/OFF keying (OOK) in information communication. It is a form similar to Power is transmitted in units of packets by power packets, and information is transmitted by time intervals in time-divided power packets. This enables simultaneous multiplex transmission of power and information.

[Physical layer]
A configuration related to the physical layer of the first layer will be described below.
(microwave transmission)
Wireless power transmission using microwaves is expected to be applied in various fields, such as power transmission to moving objects such as space solar power plants, electric vehicles, and unmanned aerial vehicles (UAVs). The frequency of microwaves used is 1 to 30 GHz, and the power transmission distance can be from several meters to several kilometers or longer, making it suitable for long-distance transmission. In microwave transmission, a rectifier is used for a power receiving antenna to DC-convert the received power. Considering the safety of the human body and high-efficiency transmission, a power transmitter with directivity such as an array antenna is suitable. The power receiver is mainly composed of a power receiving antenna and a rectifier (rectifier), and is called a rectenna as a coined word combining these.

(far field/near field)
The electromagnetic field distribution around the antenna depends on the size of the antenna and the distance between the transmitter and receiver. The area far enough from the antenna is called the far field, and the radiated electromagnetic waves are spherical waves, for which plane wave approximation is valid. On the other hand, in the far field, the received power Pr is expressed by the following formula according to the Friis formula.

（１）
ただし、λは波長、Ｇt及びＧrはそれぞれ送電アンテナと受電アンテナの利得、Ａt及びＡrはそれぞれ送電アンテナと受電アンテナの有効開口面積、Ｄは送受信間距離、Ｐtは送電電力である。

(1)
is the wavelength, Gt and Gr are the gains of the power transmitting and receiving antennas, respectively, At and Ar are the effective aperture areas of the power transmitting and receiving antennas, D is the distance between the transmitter and receiver, and Pt is the transmitted power.

Since an electromagnetic wave is originally a spherical wave, the power transmission efficiency is less than 1% in the far field where the electromagnetic wave energy spreads enough to approximate a plane wave.

On the other hand, in the near-field (Fresnel field), the radiation pattern of the antenna gradually changes as the distance to the antenna becomes shorter. Therefore, in the near field, the received power is integrated in the plane of the receiving antenna for calculation. The beam collection efficiency in the near field is expressed by the following equation.

（２）
ここで、

(2)
here,

（３）
である。

(3)
is.

Note that Equation (2) assumes two aperture antennas in which the power transmitting antenna and the power receiving antenna face each other. A clear boundary between the near field and the far field is not determined, and according to the following formula, when the distance is large, it can be regarded as the far field.

（４）
ここで、Ｄは送電距離、Ｌはアンテナの最大サイズである。
本発明の無線電力伝送システムでは近傍界を想定している。

(4)
where D is the transmission distance and L is the maximum size of the antenna.
A near field is assumed in the wireless power transmission system of the present invention.

(rectenna)
In wireless power transmission using microwaves, a rectifying antenna called a rectenna is used as a power receiver.

FIG. 3 shows the configuration of the rectenna. Rectenna 20 is composed of antenna 21 and rectifier 22 . The rectifier 22 is a passive element having a rectifying diode 22b, rectifies the microwave power received by the antenna 21, generates DC power, and supplies the load 30 with the DC power. The rectenna 20 includes a matching circuit 22a and a filter 22c in addition to a rectifying diode 22b. The matching circuit 22a matches the impedance with the antenna 21 and suppresses the generation of reflected power. Filter 22c comprises a low pass filter and an output filter. The low-pass filter suppresses high frequency re-radiation from the rectifier diode 22b, and the output filter stabilizes the DC current to increase power conversion efficiency (PCE).

FIG. 4 shows the power conversion efficiency (PCE) versus frequency. The power conversion efficiency (PCE) has the characteristic of degrading up to high frequencies.

(Power supply efficiency)
In wireless power transmission, power supply efficiency is represented by the product of power transmission efficiency and power conversion efficiency. The present invention has two modes for improving power supply efficiency.
There is a trade-off relationship with respect to frequency between power transmission efficiency and power conversion efficiency. A first form is a form in which the power feeding efficiency is improved by this frequency. A second form is a form in which the power feeding efficiency is improved by a relay node.

(a) First Mode: Improvement Mode of Power Supply Efficiency by Frequency Selection First, the first mode by frequency selection will be described. In the first mode, the frequency is selected according to the position of the power receiving terminal based on the characteristic that the frequency that optimizes power supply efficiency changes depending on the position of the power receiving terminal.

Currently, in the microwave frequency band, the ISM band "2.4 GHz" or "5.8 GHz" or the like, or the quasi-millimeter wave band "22-29 GHz" is used from the viewpoint of legal regulations. It is planned to be Since there is a frequency trade-off between power transmission efficiency and power conversion efficiency, and the frequency that maximizes power transmission efficiency depends on the magnitude of the beam tilt angle, there is a wavenumber that maximizes power supply efficiency.

In the frequency selection according to the first mode, the frequency of the microwave is made variable, the optimum frequency that maximizes the power supply efficiency (=power transmission efficiency x power conversion efficiency) is selected, and the power supply frequency is selected according to the position of the power receiving terminal. adaptively change

(system model and assumptions)
FIG. 5 shows a system model for frequency selection. Here, there is one power transmitter 1 and one power receiver 2, and the power transmitter 1 has an ideal linear array antenna with the number of antenna elements n and the element spacing d, and is fixed.

The prerequisites are as follows.
(1) Element spacing d is constant.
(2) The antenna element has ideal omnidirectionality and broadband.
(3) The power transmitter receives the position information of the power receiver from the power receiver, internally calculates the beam tilt angle θ ₀ viewed from the power transmitter and the transmission distance D, and transmits power in that direction.
(4) The receiver is a mobile terminal having an antenna with an aperture area Ar.
(5) The receiver has its own position information, and transmits information about its position to the transmitter at regular intervals.
(6) The transmitter and receiver face each other, and the propagation path environment is a two-wave model in which a direct wave and one multipath wave exist.

(Analysis model)
In the following, the power transmission antenna model and the power transmission efficiency are analyzed based on the fact that the antenna gain of the power transmission array antenna and the power conversion efficiency of the rectenna of the power receiving terminal depend on the frequency.

- Power Transmission Antenna Model FIG. 6 shows a power transmission antenna model, showing an example of an ideal two-dimensional linear array antenna. The two-dimensional linear array antenna has 1 to N linearly arranged antennas 1 to N, and the distance between the antennas is d. The array gain G at the beam tilt angle θ ₀ is expressed by the following equation.

（５）
ここで,u=d／κ_０（sinθ-cosθ_０）であり、κ_０=2πλは波数、ｄはアンテナ素子間隔、Ｎはアンテナ素子数である。

(5)
Here, u=d/κ ₀ (sin θ−cos θ ₀ ), κ ₀ =2πλ is the number of waves, d is the antenna element spacing, and N is the number of antenna elements.

Power Transmission Efficiency (PTE) is defined by the following formula

（６）
ここで,Ｐrは受電マイクロ波電力であり、Ｐｔは送電マイクロ波電力である。また、Ｐrfree（t）は自由空間伝搬環境における受電電力である。

(6)
where Pr is the received microwave power and Pt is the transmitted microwave power. Prfree(t) is the received power in the free space propagation environment.

Although the power transfer efficiency varies depending on the propagation model, as an example, the power transfer efficiency (PTE) in the free space propagation model is shown in Equation 7 below.

（７）
ここで、Ｄは送受電端末間の距離、Ａrは受電アンテナの開口面積である。

(7)
Here, D is the distance between the power transmitting/receiving terminals, and Ar is the aperture area of the power receiving antenna.

FIG. 7 shows frequency characteristics of power transmission efficiency in free space propagation. When the element spacing d in the array antenna is fixed, the higher the frequency f, the higher the array gain G. From this, the power transfer efficiency (PTE) increases as the frequency increases. When the frequency increases to some extent, the array gain G decreases due to the generation of grating lobes, and the power transmission efficiency (PTE) decreases.

・Power transmission efficiency Indicates the power conversion efficiency of a mobile power receiving terminal that has a rectenna inside the terminal. Here, it is assumed that the power receiving terminal has a battery in the terminal, and the battery can be charged with the received power. The power conversion efficiency (PCE) of the rectenna is represented by the following formula.

（８）
ここで、ＰDCは出力ＤＣ電力,Ｖ_０は抵抗性負荷の出力自己バイアスＤＣ電圧、Ｖbiはフォアードバイアス領域でのダイオードのビルトーイン電圧、Ｒsはダイオードの直列抵抗、ＲlはＤＣ負荷抵抗である。

(8)
where PDC is the output DC power, _V0 is the output self-biased DC voltage of the resistive load, Vbi is the built-in voltage of the diode in the forward bias region, Rs is the series resistance of the diode, and Rl is the DC load resistance.

θ _on and C _j are represented by the following equations.

（９）

(9)

（１０）
ここで、Ｃは_ｊ非線形ジャンクション容量であり、Ｃ_０はゼロバイアスジャンクション容量である。図８はＰＣＥの周波数特性を示している。一般的に、ＰＣＥは周波数が低いほど良い特性を示す。

(10)
where C is _{the j} non-linear junction capacitance and _C0 is the zero-bias junction capacitance. FIG. 8 shows the frequency characteristics of PCE. In general, PCE exhibits better characteristics at lower frequencies.

- Frequency Selection of Power Transmitter Below, the flow of frequency selection of the power transmitter will be described with reference to the flowchart of FIG.
(1) Acquire the information PTE of the power transmission efficiency of the rectenna and the information PCE of the power conversion efficiency.
(2) On the power transmission side, the power transmission efficiency PTE is calculated for each frequency based on the information PTE of the power transmission efficiency of the rectenna and the information PCE of the power conversion efficiency. A frequency characteristic of power transmission efficiency (PTE) is calculated to determine a threshold value θth, frequencies flow and fhigh.
(3) The power transmitter acquires the position information of the power receiving terminal, and calculates the beam tilt angle θ ₀ (t) and the distance D(t) between power transmission and reception based on the acquired position information and the position of the power transmitter itself.
(4) When the beam tilt angle θ ₀ (t) is greater than the threshold θth, flow is selected and power is transmitted.
(5) Feedback received power.
(6) If the received power is less than the value Prfree(t) in the free space propagation environment, it is determined that the phase is reversed due to multipath effects, and the frequency is changed to fhigh.
(7) When the beam tilt angle θ ₀ (t) is smaller than the threshold θth, fhigh is selected and power is similarly transmitted.
(8) Repeat (4) to (7) to adaptively control the frequency.
・Propagation model

FIG. 10 shows the propagation model. Here, a two-path model propagation model consisting of one direct wave and one multipath wave is shown. It is assumed that the arrival time of the direct wave is 0, and the delayed wave is received with a delay of the amplitude a times and the phase δ. The composite wave at this time is represented by the following equation.

（１１）

(11)

After calculating the average absolute value of the two waves using Equation (12), the received power is calculated using Equation (13). where _Z0 is the characteristic impedance of the electromagnetic wave.

（１２）

(12)

（１３）

(13)

Performance Evaluation by Simulation Hereinafter, performance evaluation by simulation will be shown using an evaluation function f(θ ₀ , ω)=PTE*PCE.
The parameters of the transmission array antenna, the parameters of the rectenna, and the parameters of the propagation environment are shown.

FIG. 11 shows the frequency characteristics of power supply efficiency when the angle is changed by 15 degrees. The power supply efficiency is compared while changing the beam tilt angle θ0 from 0° to 60°. The frequency characteristics of the power supply efficiency in FIG. 11 show that the frequency that maximizes the power supply efficiency changes as the beam tilt angle changes. For example, when theta0 = 0 [deg], the efficiency is highest at about 2.8 GHz. It shows that the efficiency of high frequencies is high.

The simulation result is
(1) It is effective to transmit power by varying the frequency according to the position of the receiving terminal.
(2) In a free-space propagation environment, the optimum frequency that maximizes the power supply efficiency changes when the beam tilt angle θ0 is changed.
(3) In a multipath environment, power supply efficiency is improved compared to a wireless power transmission system using a single frequency.
is shown.

Angular average efficiency of wireless power transmission system Evaluate the performance of frequency switching by

Here, 2.4 GHz and 3.8 GHz, which have high power feeding efficiency, are selected with reference to the results of FIG. It does not optimize frequency.

A single frequency of 3.8 GHz is used for performance comparison as an existing method. The propagation model evaluates the average power supply efficiency when the power receiving terminal randomly moves from 0 [deg] to 60 [deg] as a two-wave model. The number of trials is 100 times.

FIG. 12 compares the average power supply efficiency between a wireless power transmission system by frequency selection using the algorithm of the present invention and a system using a single frequency. The frequency selection of the present invention improves power supply efficiency compared to existing fixed frequencies. In FIG. 12, the same phase frequency is used instead of using the frequency when the anti-phase multipath is received.

(b) Second Form: Improvement of Power Supply Efficiency by Multihop Relay Next, a second form by multihop relay will be described. There is a problem that it is difficult to improve the power transmission efficiency when the power transmission distance is long. A second form improves power supply efficiency by arranging a repeater node (drone) and transmitting power by a multi-hop relay.

In wireless power transmission of microwave transmission, power supply efficiency is affected because attenuation occurs in the square of the distance. For example, in power supply to drones, one of the issues is the spacing between drones that enables wireless power transmission. The present invention enables long-distance power transmission through multi-hop relays. A repeater is provided between the power transmitter and the power receiver, and power is transmitted and received via the repeater, thereby performing power feeding by a multi-hop relay. As a result, power attenuation in power transmission due to power transmission distance is reduced, and the amount of power supplied is improved.
In addition, regarding power receiving nodes that are expected to move (mobility) such as drones, position fluctuation due to hovering. Adaptive directivity control (adaptive beamforming) in the physical layer according to direction, speed, acceleration, etc., adaptive access control protocol in the MAC layer, and adaptive route selection (routing) in the network layer can be applied. .
A first form and a second form of multi-hop relay will be described below.

(b1) First form of multi-hop relay A first form of multi-hop relay will be described. FIG. 13 shows a power supply model using multi-hop relays. Here, a power supply model is shown in which power is supplied from a fixed power transmitter 1 to a power receiver 2 via a plurality of repeaters 3 . Here, movable power receiving terminals RS1 to RSn-1 are shown as the repeater 3. FIG. For example, drones can be used as the power receiving terminals RS1 to RSn-1.

It is assumed that the power transmitter 1 is an ideal linear array antenna, the power receiving terminals RS1 to RSn-1 including the repeater 3 are movable, and the power receiving terminals RS1 to RSn-1 and the power receiver 2 are connected. are D1 to Dn, the transmission power of all terminals is the same, the antenna aperture areas of the transmitter 1 and the receiver 2 are At and Ar, the effects of noise and interference are ignored, and the distance attenuation due to free propagation is LOSS is the loss rate due to the repeater.

According to the wireless power transmission of the present invention, the total attenuation of the loss due to all repeaters and the distance attenuation between all repeaters is greater than the attenuation of the total distance D due to direct power transmission between the transmitter and the receiver. reduced.

・End to End Power Supply Efficiency Assuming that the distances between power receiving terminals are D1, D2, etc., using the Friis formula that considers the near field, the power supply amount in the free space propagation model is expressed by the following formula. .

（１４）
ここで、Ｐ_０は送電機の送電電力、PCEはレクテナの電力変換効率、LOSSは中継ノードの損失、Ａtは送電機のアンテナの開口面積、Ａrは中継ノードのアンテナ開口面積、λはマイクロ波の波長である。

(14)
where P ₀ is the transmitted power of the transmitter, PCE is the power conversion efficiency of the rectenna, LOSS is the relay node loss, At is the transmitter antenna aperture area, Ar is the relay node antenna aperture area, and λ is the microwave is the wavelength of

In equation (14), (1-exp(-At.Ar/( ^λ2.D12 ))) represents the feed rate sent due to distance attenuation between the transmitter and ^the repeater, and (1-exp( -Ar ² /(λ ² Di ² )) represents the feed rate sent due to distance attenuation between repeaters.When the number of repeaters is (M-1), distance attenuation occurs m times, is (m-1) times, PCE is the power conversion efficiency of the rectenna.

- Simulation example of multi-hop relay Below, the simulation example of the wireless power transmission of this invention is shown. Here, it is assumed that the drone of the power receiving terminal is not affected by wind, there are no obstacles such as people or buildings around, and there is no effect of delayed waves, etc., and free space propagation is assumed without considering noise and interference. Only attenuation due to distance propagation is considered in the model.

It is assumed that the repeaters of each node are arranged in a straight line from the transmitter to the receiver, the height and transmission power of each node are all equal, and the direct wave is incident perpendicularly to each antenna plane. Also, the transmitter uses a linear array antenna. Table 4 below shows the simulation specifications.

FIG. 14 shows the amount of power supplied by the multi-hop relay, showing power efficiency [%] against the number of hops. The amount of power supplied when the number of repeaters is changed from 0 to 9 is calculated using equation (14).

In FIG. 14, the number of hops is 0 when power is transmitted by direct waves without a repeater, and the numbers of hops 1 to 9 are when power is transmitted via a repeater. FIG. 14 shows that the power supply amount of a multi-hop relay that transmits power while relaying relays is greater than that of power transmission by direct waves, and that the power supply amount with 5 hops is the maximum.

A simple example of the optimal number of pops is described below.
The optimum number of pops and the optimum number of repeaters can be determined based on equation (14).

In the equation (14) representing the feed amount, (1-exp(-Ar ² /(λ ² ·Di ² ))) represents the feed rate sent due to distance attenuation between repeaters. The logarithm of this feed rate is differentiated by the number i of repeaters, and the optimum number of repeaters is obtained from the number i that satisfies ln(i)=(-ln(Ar ² /(λ ² Di ² ))). can be done.

- Optimal distance between repeaters The optimum distance between repeaters will be explained. The optimum distance between repeaters can be obtained based on equation (14).

Assuming that the total transmission distance is D, in a multi-hop relay model with one repeater, the relay distances D1 and D2 of the repeater have a relationship of D=D1+D2. Differentiate the logarithm of the feed amount in equation (14) at this time with the relay distance D1, and from the relay distance D1 at which the differential value is zero, D1 = (D/2) ^1/2 is obtained as the optimum distance of the repeater. be done.

In a multi-hop relay model with more than two repeaters, the rest of the relay distances excluding the relay distance D1 can be found by associating with the relay distance D1 of the multi-hop relay model with one repeater. For example, when there are two repeaters, by associating the remaining repeater distance (D2 + D3) excluding the repeater distance D1 with the repeater distance D1 of the multi-hop relay model with one repeater,
D2 = ((D-(D/2) ^1/2 ) ^1/2 )/2 ^1/2
D3 = D - D1 - D2
is used to determine the optimum distance between repeaters.

(b2) Second form of multi-hop relay Next, a second form of multi-hop relay will be described.

- System model and preconditions The system model is shown in FIG. A relay node (relay node) RS is introduced between the power transmitter Tx and the power receiving terminal Rx. The relay node RS is a power receiving terminal and can be configured by a repeater.

The relay node RS has the following conditions.
(1) It has a power receiving antenna with a sufficiently large aperture area Ar.
(2) having a sufficiently large number of N power transmission antenna elements;
(3) The received RF power is distributed within a relay node (relay node), and the phase can be controlled during the distribution process.

・Types of relay nodes There are two types of relay nodes: "Distribution and Forward method" and "Rectification and Forward method".

(Distribution and Forward method)
A block diagram of the Distribution and Forward method is shown in FIG. The distribution and forward method is a completely passive circuit method in which the microwave power received by the power receiving antenna is not converted to direct current, but the microwave power is directly distributed by a distributor, the phase is controlled, and the power is transmitted from the antenna. be.

The advantage of this Distribution and Forward method is that the power loss at the relay node (relay node) is small because the power is not converted to direct current. On the other hand, since a relay node (relay node) does not receive power, if the relay node is a moving object such as a drone, there is a problem in travel time such as flight time.

(Rectification and forward method)
A block diagram of the rectification and forward method is shown in Figure 17. The rectification and forward method is a method in which power is rectified at a relay node (relay node), stored in a battery, and microwaves are generated again to transmit power. The advantage of the rectification and forward method is that the power is transmitted to the relay node (relay node), so if the relay node is a mobile object such as a drone, the travel time such as flight time may be extended. be. On the other hand, a relay node (relay node) rectifies and converts it into direct current, and then generates microwaves again, so there is a large loss due to the relay node (relay node).

(Comparison of transmission efficiency)
In the following, the difference of efficiency (efficiency during n-hop power transmission - efficiency during direct transmission) in an ideal environment with no beam tilt angle deviation will be described. Difference of efficiency is the efficiency comparison between the efficiency of n-hop power transmission and the efficiency of direct transmission. If the value of difference of efficiency is positive, the end-to-end efficiency of multi-hop transmission is higher than the efficiency of direct transmission. . This means that multi-hop transmission is effective. Note that direct transmission is assumed to be 0 hops.

FIG. 18 shows an example of the relationship between the number of hops and the difference of efficiency when the efficiency during direct power transmission is 2.9%. According to FIG. 18, in the simulation,
(1) The multi-hop relay characteristic deteriorates each time the hop is performed up to a certain number of hops n1. FIG. 18 shows the case where n1 is two.
(2) Multi-hop relay characteristics are improved from the hop number n1 onwards, and the effectiveness of multi-hop transmission is confirmed from a certain hop number n2. FIG. 18 shows the case where n2 is 3.
(3) After n2 hops, the efficiency of (n+1) transmission is higher than that of n-hop transmission.
(4) If the number of hops n is too large, the efficiency deteriorates from a certain number of hops n3.
By obtaining the above hop numbers n1 to n3, the optimum hop number for good transmission efficiency can be obtained.

(Assumptions and variables)
Assume the following conditions:
(1) Assume that the power transmitter, relay node, and power receiving node are arranged in a straight line.
(2) A far-field, free-space propagation model is assumed.
(3) Ignore the size of each node. (4) Consider the following losses.
Loss in the propagation path Loss when distributing and re-radiating power at the relay node Loss when converting microwave power to DC at the receiving node

Also, G(θ ₀ , f) is the gain of the array antenna, Ar is the aperture area of the power receiving antenna of RS and Rx, Dall is the total transmission distance of Tx and Rx, PCE(f) is the power conversion efficiency, and LOSSDvi is the relay node. , and let n be the number of hops. Henceforth, n∈N.

The hop count n1, hop count n2, and hop count n3 will be described below.
(Number of hops n1)
First, the number of hops n1 is obtained. The number of hops n1 is the number of hops at which (n+1) hops are more efficient than n hops, indicating that wireless power transmission by multi-hop relays is more effective than power transmission by direct waves. .
We show that (n+1) hops are more efficient than n hops when n>√(1/β). This is equivalent to finding n that satisfies the following equation.

（１５）

(15)

The minimum n that satisfies the following equation (16) is obtained from equation (15).

（１６）

(16)

Assuming that β=(G(θ ₀ , f)·Ar)/(4π·(Dall) ² )) LOSSdvi, the left side of equation (16) is expressed by the following equation.

（１７）
上記から、ｎ＞√（1／β）のとき、（ｎ＋１）ホップがｎホップよりも効率が高くなる。

(17)
From the above, when n>√(1/β), (n+1) hops are more efficient than n hops.

(Number of hops n2)
Next, the number of hops n2 is obtained. The number of hops n2 is the number of hops at which the end-to-end power supply efficiency during multi-hop transmission is higher than the efficiency during direct transmission.
The number of hops n2 at which the end-to-end power supply efficiency during multi-hop power transmission is higher than the efficiency during direct transmission is n that satisfies the following equation.

（１８）

(18)

Equation (18) can be solved by solving (β*n ² ) ⁿ −β>0, where β is set to β=((θ ₀ , f) Ar)/(4π (Dall) ² )) LOSSdvi , and the number of hops n2 satisfies the following equation.

（１９）

(19)

For the number of hops n2 or more that satisfies Equation (19), the end-to-end power supply efficiency during multi-hop transmission is higher than the efficiency during direct transmission.

(Number of hops n3)
Next, the number of hops n3 is obtained. The number of hops n3 is the number of hops that maximizes the end-to-end power supply efficiency. In the process of finding the number of hops n1, when n>√(1/β), (n+1) hops are more efficient than n hops, so n<((4π·(Dall) ² )/G(θ ₀ , f)·Ar)) ^1/2 , (n+1) hop transmission has better end-to-end power feeding efficiency than n hop transmission. On the other hand, when n>((4π·(Dall) ² )/G(θ ₀ , f)·Ar)) ^1/2 , the end-to-end power supply efficiency is less affected by RS loss. Therefore, n3 that maximizes the end-to-end power supply efficiency is expressed by the following equation.

（２０）

(20)

Furthermore, the maximum value at that time is represented by the following formula.

（２１）

(21)

Next, in order to obtain a threshold value for selecting one of the equations (20), the loss in the transmission path represented by the following equation (22) and the loss of the repeater node represented by the following equation (23) compare.

（２２）

(22)

（２３）

(23)

Comparing the two losses corresponds to comparing the magnitudes of the following equations.

（２４）

(24)

Here, if a=(G(θ ₀ , f)·Ar)/(4π·Dall) and κ=LOSS _dvi , n is expressed by the following equation.

（２５）

(25)

With this n, the optimum number of hops n3 is expressed by the following equation.

（２６）

(26)

(Performance evaluation of multi-hop relay considering beam tilt angle error)
Next, performance evaluation considering the beam tilt angle error will be described for the first and second forms of the multi-hop relay described above.

(Influence of positioning error)
FIG. 19 shows an outline of the positioning error of a movable repeater node (power receiving terminal) such as a drone. The positioning error of the repeater node (power receiving terminal) is measured outdoors using the GNSS system. On the other hand, in areas where radio waves from the GNSS system do not reach, such as inside man-made objects such as buildings, and indoors and outdoors where higher-precision positioning and ranging are required, positioning is performed by an Ultra Wide Band (UWB) system. Due to such differences in environment, it is assumed that positioning errors exist as shown in FIG. 20, and the positioning errors are cumulatively accumulated by sequential positioning of the UWB system.
According to the current domestic and international radio laws, UWB radio is a radio wave with a bandwidth of 450 MHz (500 MHz) or more or a relative bandwidth (bandwidth/center frequency) of 20% or more. In the microwave band, 3.4 = 4.8 GHz for Low Band and 7.25 to 10.25 GHz for High Band are stipulated by the Radio Law of Japan. 22-29 GHz is specified, and 79 GHz is specified overseas. In particular, in wireless power transmission, the quasi-millimeter wave band 22 to 29 GHz is also targeted in addition to the ISM band, and the quasi-millimeter wave band UWB is also put into practical use under the Radio Law.

(Simulation example)
- Simulation environment Table 5 shows the parameters of the receiving node, Table 6 shows the parameters of the relay node, and Table 7 shows the parameters of the propagation model in the second form of the multi-hop relay.

なお、ビームチルト角誤差はドローンのピッチ角とビームチルト角の差と定義され、その誤差分布はガウス分布もしくは一様分布に従うものとしている。

The beam tilt angle error is defined as the difference between the pitch angle of the drone and the beam tilt angle, and the error distribution follows Gaussian distribution or uniform distribution.

-Assumed Environment FIG. 20 shows an assumed environment. Here, it is assumed that the closer the node is to the power receiving node, the larger the beam tilt angle error due to the influence of the cumulative error of the UWB system.

(simulation result)
Simulation results for a case where the angular error follows a uniform distribution and a case where the power transmission frequency is changed for each hop are shown below.

・When the angular error follows a uniform distribution For the case where the error distribution follows a uniform distribution, FIG. showing.
The end-to-end power supply efficiency has a characteristic with a negative slope with respect to angular deviation, and in the low frequency range, has a characteristic with almost positive slope with respect to frequency. It is shown that.

- Change of power transmission frequency for each hop Fig. 23 shows the relationship between the frequency and the end-to-end power supply efficiency. The end-to-end power supply efficiency for single frequencies of 0 GHz, 2.5 GHz, and 3.00 GHz is shown in comparison. This result indicates the effectiveness of the wireless power transmission system using microwave frequency selective multi-hop relays that change the frequency for each hop.

(repeater with amplification function)
Multi-hop relays improve the amount of power supply, but the amount of power supply decreases for long-distance power transmission.

By configuring the repeater of the present invention to have an amplification function (ET (Energy Transmitter) function), power is amplified by the repeater, thereby alleviating a decrease in the amount of power supplied in long-distance transmission.

Let P be the transmitted power of the transmitter, Y be the required power amount of the receiver, and when power is supplied by multi-hop relays using n repeaters, each repeater amplifies the power x.

At this time, the relationship between the power amount P1 after being amplified at the first hop and the transmitted power P sent from the power transmission source is represented by the following equation.

（２７）

(27)

The relationship between the (n-2)th hop power amount Pn-2 and the (n-1)th hop power amount Pn-1 is expressed by the following equation.

（２８）

(28)

Also, the relationship between the (n-1)-th hop power amount Pn-1 and the n-th hop power amount Pn is represented by the following equation.

（２９）

(29)

where A is

（３０）
としている。

(30)
and

From these equations, the received power P(n) at the n-th hop is expressed by the following equation.

（３１）

(31)

There is a relationship represented by the following formula among the required power amount Y, the power conversion efficiency PCE, and the received power P(n).

（３２）
各中継器で増幅する中継増幅量ｘは以下の式により導出される。

(32)
A relay amplification amount x amplified by each repeater is derived from the following equation.

（３３）

(33)

(Simulation example of repeater with amplification function)
FIG. 24 shows the total amount of amplification in each repeater for sending the required amount of power. 5P to P O.D. A simulation example in the case of changing by a width of 1 is shown. The specifications of the simulation are the same as those in Table 1, and are a free space propagation model.

According to the simulation example of FIG. 24, the total amplification amount of each repeater is the minimum in the case of 5 hops where the number of repeaters is 5. This result agrees with the result that the total amplification amount of 5 hops is the minimum when the total distance is 10m and LOSS=0.8.

The effectiveness of relay amplification is compared using FIG. 25 and Table 8.
25A and 25B are diagrams for comparing the amount of power supplied when power is amplified by a repeater and when power is amplified on the transmitter side. FIG. 25(b) shows the case where the power is amplified on the transmitter side, and the total power amount is 1.5P for both.

In the configuration shown in FIG. 25(a) where power is amplified by a repeater, the power transmission power amount P is sent from the power transmitter for a required power amount of 0.5P, and the amplified power amount is O.P. Increase 1P. On the other hand, in the configuration shown in FIG. 5P is power-amplified and (P+0.5P) is transmitted.

FIG. 26 and Table 8 compare power supply amounts at the last power receiving node when power is amplified by the repeater and when power is amplified by the power transmitter.

For example, when there are two power receiving terminals RS, the amount of power supplied to the last power receiving node is 0.24 P when the power is amplified by the transmitter, whereas it is 0.5 P when the power is amplified by the repeater. becomes. It is shown that the amount of increase in power supply due to power amplification by the repeater is 0.14P to 0.26P compared to power amplification by the power transmitter.

(Improvement of power supply efficiency by frequency selection considering reflected waves)
In an environment where microwaves propagate, a propagation model in a more realistic environment is required to consider the effects of reflected waves, as opposed to a free-space propagation model that does not consider reflected waves.

FIG. 27 shows a two-wave model of a direct wave and a reflected wave in consideration of reflected waves. Between the power transmitter and the power receiving terminal RS, between the adjacent power receiving terminals RS, and between the power receiving terminal RS and the power receiver, in addition to direct waves, reflected waves reflected by the ground are received. In the case of this two-wave model, there is a case where the amount of power supplied becomes extremely small due to the phase relationship between the two waves depending on the distance between the receiving terminals.

The feed amount P(Δθ) considering the phase shift Δθ in the two-wave model is expressed by the following equation.

（３４）

(34)

FIG. 28 shows the result of normalization by the area where the phases match in the superimposition of two waves in Equation (34). where Δθ is the phase shift. In FIG. 28, when the reflected wave is 1/5 (=-7 [dB]) of the direct wave, when the phase shift Δθ is between 96° and 180°, the phase is lower than when the direct wave is transmitted. This indicates that the amount of power supplied decreases due to the deviation.

The present invention eliminates the phase shift by selecting the optimal frequency for the microwave frequency to be transmitted according to the distance between the receiving terminals (repeaters), and feeds power by matching the phases so that the power of the two waves strengthens each other. Increase quantity.

(Optimal frequency derivation flow)
A procedure for deriving the optimum frequency will be described with reference to the flowchart of FIG. First, relay node distance information is sent to the power transmitter side (S1), and the power transmitter acquires the relay node distance information (S2). Based on the obtained distance between relay nodes, the power transmitter calculates the path difference between the direct wave and the ground-reflected wave (S3). A phase shift Δθ between the two waves is calculated (S4).

In the relationship between the phase shift Δθ and the power shown in FIG. 28, the range of the phase shift Δθ where the power is less than the set amount of power is obtained. Judging that the feed amount of the wave and the reflected wave is smaller than that of the direct wave only, the frequency of the microwave is changed. The range of phase shift from 96° to 180° corresponds to the case where the reflected wave exceeds 1/5 (=-7 [dB]) of the direct wave, and the phase shift range depends on the set value. set to the value

The optimum frequency is derived from the phase of the direct wave obtained from the distance between relay nodes and the frequency of the direct wave, and the phase of the ground reflected wave obtained from the distance between the relay node and the ground and the frequency of the ground reflected wave. It is determined by the frequency at which the deviation is within the set range. If there is no frequency difference between the frequency of the direct wave and the frequency of the ground reflected wave, the frequency of the microwave sent from the power transmitter can be used in common (S5). Power is supplied with microwaves of the calculated optimum frequency (S6).

(Simulation example by frequency selection)
FIG. 30 shows the amount of power supplied when the frequency is changed. Here, in the two-wave model, the direct wave and the reflected wave weaken each other due to the phase shift, and when the phase shift exceeds 96°, the microwave frequency is changed from 1.5 GHz to 3.0 GHz, The amount of power supplied when the frequency that provides the best amount of power is selected from among these frequency changes is compared with the amount of power supplied before the frequency is changed. According to FIG. 30, it is confirmed that the power supply amount is improved by changing the frequency.

FIG. 31 shows the optimum number of hops with respect to the total distance when the frequency is changed, comparing before and after changing the frequency. According to FIG. 31, it is confirmed that the optimum number of hops decreases when the frequency is changed.

From FIGS. 30 and 31, it is confirmed that frequency selection is effective in reducing the optimum number of hops and improving the power supply amount at the optimum number of hops.

FIG. 32 shows an example of optimal frequency simulation for the distance between nodes (the distance between power receiving terminals). Note that the height of the node from the ground is 3 m here.

(Wireless power transmission and wireless information transmission)
When wireless power transmission (WPT) and wireless information transmission (WICT) are performed simultaneously by the multi-hop relay of the present invention, the sum of the power supply efficiency in wireless power transmission and the path signal-to-noise ratio in wireless information transmission is used as an evaluation index. power supply route can be selected.

In a route with a pair of transmitter and receiver and multiple repeaters as nodes,
(1) In wireless power transmission, in a weighted graph in which the weight of the path corresponds to the power transmission efficiency between adjacent repeaters, the sum of the weights of the power transmission paths between the transmitter and the receiver is calculated using the Dijkstra method. is the power supply efficiency, and
(2) In wireless information transmission, in a route with a pair of transmitter/receiver and multiple repeaters as nodes, the weight of the route corresponds to the signal-to-noise ratio (S/N ratio) between adjacent repeaters. In the graph, the sum of the weights of the information transmission paths between the transmitter and the receiver is defined as the path signal-to-noise ratio by Dijkstra's method,
(3) The route that maximizes the sum of the weighted additions of the power feeding efficiency and the route signal-to-noise ratio is taken as the power feeding route of the optimized network.

(Technology related to physical layer)
In addition to the multi-hop relay WPT method, which enables long-distance wireless power transmission between multiple drones, mobile terminals, and other mobile power receiving terminals, there are the following related technologies applied to the physical layer.

(1) On/Off Keying (OOK) and CODE Shift Keying (CSK) are available as modulation schemes and channel coding techniques in the physical layer.
(2) As an error correction technique in the physical layer, there is RunLength-limited/weight-distribution-limited error correction code with constraints (LDPC/polar code, etc.).
(3) Spatial diversity/MIMO-WPT system by transmitting and receiving power from multiple antennas.
(4) MISO-WPT scheme from a plurality of power transmitting terminals to a single power receiving terminal, or SIMO-WPT scheme from a single power transmitting terminal to a plurality of power receiving terminals.
(5) A spread spectrum transmission system and an ultra-wideband (UWB) transmission system that are resistant to disturbances such as the characteristics of power transmission lines and interference.
(6) Code division multiple access CDMA-WPT system with multiple transmission/reception modes using code orthogonality.
(7) Frequency/time/space/code division multiple access integrated FDMA/TDMA/SDMA/CDMA-WPT transmission/reception system.
(8) Adaptive directivity/transmission power/Duty Cycle control system according to transmission/reception terminal and transmission path environment.

[Network layer]
Next, a configuration related to the network layer of the second layer will be described.
(Selection of optimum power supply route)
FIG. 33 shows a schematic configuration of a power transmitter 1, a repeater 3, and a power receiver 2 in a wireless power transmission system using multi-hop relays. In this configuration, it is assumed that the propagation model is free space propagation, the loss of the power receiver and the repeater is constant, the power transmission and reception antenna has a sufficiently large number of elements, and that they are facing each other. The end-to-end power supply efficiency eff from end to end is formulated by equation (35).

（３５）

(35)

In equation (35), n is the number of hops, Pt and Pr are power transmission and reception power, At and Ar are the effective area of the power transmission and reception antenna, Di is the distance between i hops, λ is the wavelength of the electromagnetic wave, and LOSS is the relay. Loss, PCE (Power Conversion Efficiency), is the power conversion efficiency of the rectenna.

As shown in FIG. 34, assuming an environment in which there are multiple repeater (power receiving terminal) candidates between the end-to-end of the power transmitter and the power receiver, multiple Select the optimum power supply route from the power supply routes of

Selection of the optimum power supply route includes the choice of which node's repeater to use, or direct power supply in one hop without using a repeater. Since the received power density decreases in proportion to the square of the transmission distance, the end-to-end power supply efficiency greatly decreases depending on the repeater used.

The present invention uses Dijkstra's method to select the optimum power supply route with the best end-to-end power supply efficiency.

The Dijkstra method is a method of finding a route that minimizes the sum of weights of routes between two nodes in a weighted graph. In the selection of the optimum power supply route using the Dijkstra method of the present invention, the power supply route with the maximum end-to-end power supply efficiency is obtained by associating the weight of the route with the power transmission efficiency per hop. At this time, it is assumed that the power transmitter knows its own position information, loss LOSS as repeater efficiency, power conversion efficiency PCE of rectenna, aperture area of repeater antennas of all nodes, and wavelength λ used for power supply. Also, it is assumed that the repeater and the power receiver have known location information of themselves and the power transmitter.

FIG. 35 is a diagram for explaining the weighted graph. In FIG. 35, a circle indicates a node, and a start node marked with S is indicated. The number attached to the route connecting each node indicates the weight. Dijkstra's method finds a route that minimizes the sum of the weights of the routes between the starting point and the node.

(weight)
In the selection of the optimum power supply route using the Dijkstra method, weighting is performed to maximize the end-to-end power supply efficiency eff. Since the Dijkstra method selects a route that minimizes the sum of weights, maximizing the power supply efficiency eff comes down to minimizing the reciprocal of the power supply efficiency eff (1/eff). (1/eff) is represented by the following formula.

（３６）

(36)

Also, minimizing (1/eff) of one hop is equivalent to minimizing log(1/eff). log(1/eff) is represented by the following formula.

（３７）

(37)

The i-th term in equation (37) is the logarithm of the reciprocal of (power at i hops)/(power at i-1 hops), which corresponds to the logarithm of the reciprocal of the efficiency between i hops. .
Let each term in Equation (37) be the weight of the power feeding route formed by the link connecting the power transmission and reception. The optimum power supply route is selected by the power transmitter, and the weight is used to determine the power supply route with the best end-to-end power supply efficiency by using the Dijkstra method.

In order for the power transmitter to perform weighting in selecting the optimum power supply route, the power transmitter is required to know the positional information of the repeater and the power receiver. The relay or the power receiver transmits the position information to the power transmitter, and the power transmitter acquires the position information of the relay and the power receiver.

(How to send location information)
Next, a method of transmitting the positional information of the power receiver and the repeater to the power transmitter will be described. Assuming long-distance power supply, the distance between the power transmitter and the repeater (node) may exceed the communication range. Therefore, it is necessary to transmit the distance information using a multi-hop relay as well. In this case, each repeater (node) uses existing communication routing methods (AODV, etc.) to transmit location information, which may increase power consumption.

Therefore, in the multi-hop relay for power supply, the present invention transmits location information with low power consumption by the transmission method described below.

FIG. 36 is a diagram for explaining communication of position information in a multi-hop relay for feeding. The location information is transmitted by flooding a packet including the location information from the power receiver to the power transmitter via each repeater. The receiver broadcasts EREQ (Energy Request) packets, the repeater rebroadcasts the received EREQ (Energy Request) packets, and the transmitter acquires and weights the location information contained in the received EREQ (Energy Request) packets Create graphs.

Note that broadcasting intentionally performs transmission from all ports based on transmission to the broadcast MAC address, whereas flooding performs transmission from all ports when there is no transmission destination MAC address in the MAC address table.

A method of transmitting position information will be described below with reference to the flow charts of FIGS.

- Flow of receiving power Fig. 37 shows the flow of receiving power for broadcasting an EREQ (Energy Request) packet. The EREQ packet is a packet for notifying the power transmitter that the power receiver requests power supply. If the distance between the receiver and transmitter is long, direct communication may not be possible, so EREQ packets are flooded to inform the transmitter of the power supply request. At this time, by adding the location information of the power receiver to the EREQ packet (S11), the location information of the power receiver is transmitted at the same time as the power supply request (S12).

- Repeater (node) flow Fig. 38 shows the flow of rebroadcasting an EREQ packet by a repeater (node).

When the repeater (node) receives the EREQ packet (S21), it rebroadcasts the EREQ packet. At this time, if the following conditions are simultaneously satisfied (S22), the repeater adds its own location information to the EREQ packet (S23) and then broadcasts (S24).
Condition 1: Distance between receiver and transmitter > Distance between repeater and receiver Condition 2: Distance between receiver and transmitter > Distance between repeater and transmitter

FIG. 39 is a diagram for explaining conditions for transmitting location information of a repeater.
If a repeater that satisfies both the above conditions 1 and 2 is used for relaying,
(distance between receiver and repeater + distance between repeater and receiver) < (distance between receiver and transmitter)
Therefore, power feeding by multi-hop relay has higher end-to-end power feeding efficiency than direct power feeding. A star node in FIG. 39 indicates a repeater that satisfies both condition 1 and condition 2. FIG.

On the other hand, if a repeater that does not satisfy conditions 1 and 2 is used for relaying,
(distance between receiver and repeater + distance between repeater and receiver) > (distance between receiver and transmitter)
Therefore, power feeding by multi-hop relay has lower end-to-end power feeding efficiency than direct power feeding. Nodes marked with triangles in FIG. 39 indicate repeaters that do not satisfy the conditions 1 and 2. FIG.

Therefore, repeaters (nodes) that do not satisfy conditions 1 and 2 are not used for relaying, so there is no need to transmit the position information of those repeaters. As a result, it is possible to limit the nodes that transmit position information, and to reduce power consumption by not transmitting unnecessary position information.

Flow of Power Transmitter FIG. 40 shows a flow of rebroadcasting an EREQ packet by a repeater (node).
After receiving the EREQ packet (S31), the power transmitter acquires the location information of the receiver or repeater included in the EREQ packet, adds the new location information to the list (S32), and receives the EREQ packet. After a certain amount of time has passed (S33), weights are calculated to create a weighted graph (S34), a power supply route is searched using the Dijkstra method (S35), and power is supplied using the determined power supply route. I do. Instead of continuous power supply, power is supplied in power packets divided into packets (S36).

In the communication method, power consumption can be reduced by transmitting location information at the same time as an EREQ packet (power supply request packet) and limiting the nodes that transmit location information.

(Simulation example)
Next, a simulation of selection of a power feeding route for wireless power feeding by a multi-hop relay will be shown. At this time, the ideal power supply efficiency, the power supply efficiency using the present invention, and the end-to-end power supply efficiency in the case of one-hop power supply are shown in comparison. The ideal power supply efficiency is the power supply efficiency of the route with the highest power supply efficiency in the given arrangement of the power transmitter, repeater, and power receiver. Power consumption is also shown.

The preconditions for the simulation are as follows.
・The simulated propagation space is assumed to be a two-dimensional space.
・Place the nodes in a circle centered on the node that transmits power.
・Nodes are arranged using uniform random numbers.
・All nodes other than transmitters and receivers are candidates for repeaters (nodes).
・Transmission errors due to packet collisions and interference are not considered.
・Do not consider the movement of repeaters (nodes).
- Evaluate the average value of 50 times.
The simulation specifications are as follows.

（想定環境の諸元）

(Specifications of assumed environment)

（アンテナの諸元）

(Antenna specifications)

（EREQパケットの諸元）

(Specifications of EREQ packet)

41 to 44 show the simulation results of the number of nodes and the average power supply efficiency of the end-to-end power supply efficiency, and show the cases where the total power transmission distance is 10m, 20m, 30m, and 40m, respectively.

When the power transmission range is 10m to 30m, the ideal power supply efficiency and the power supply efficiency of the power supply route by the multi-hop relay according to the present invention match. This indicates that the power supply route according to the present invention selects a power supply route that maximizes the end-to-end power supply efficiency. Also, as the number of nodes increases, the power supply efficiency increases compared to the one-hop case. This confirms that the multi-hop relay of the present invention improves the efficiency of long-distance power supply.

FIG. 45 shows power consumption by communication with respect to the number of nodes. FIG. 45 shows that as the number of nodes increases, the power consumption increases due to the increase in transmission and reception of packets. In addition, as the power transmission range expands, transmission and reception of packets containing a lot of location information increases, resulting in an increase in power consumption.

(Technology related to network layer)
Related technologies applied to the network layer include the following technologies.

(1) Contention-based CSMAS-CA-type WPT that packetizes the power transmission distance, detects and avoids the concentration (contention) of power transmission packets (power packets) from multiple nodes by carrier sense, and avoids collisions and retransmits protocol.
(2) Preserve-type, Contention-free TDMA-type WPT protocol that allocates time slots for transmission packets (information packets) from multiple nodes in a time division manner.
(3) A hybrid WPT protocol of Contention Free and Contention Base, which is the standard for medical wireless BANs.
(4) A WPT protocol that phase-synthesizes collisions of transmission packets (power packets) from multiple nodes to maximize received power.

[MAC layer]
Next, a configuration related to the MAC layer of the second layer will be described.
(Access control by MAC layer)
In the wireless power transmission system of the present invention, the MAC layer of the second layer for controlling power transmission and reception between a plurality of nodes has a plurality of protocols, and transmits and receives power from a plurality of power transmission nodes (power supply nodes) to one power reception node. , access control in power transmission and reception between a plurality of nodes for total power reception from one power receiving node to a plurality of power transmission nodes (power feeding nodes).

This MAC layer access control cooperates with the network layer to control the simultaneous multiplexing of power and information. In the access control of the MAC layer, simultaneous multiplex transmission of power and information is possible by performing time-series control of power packets and information packets. do.

An example of the MAC layer protocol is shown below. Protocols (1) to (3) are examples of protocols that avoid power packet collisions. In the following description, the term "power packet" is used for the power packet, and the term "transmission packet" is used for the information pulse.
(1) The MAC layer has a protocol for packetizing power transmission intervals, detecting and avoiding collisions of power transmission packets from multiple nodes by carrier sense, and retransmitting the packets.
(2) The MAC layer has a protocol that allocates time slots for transmission packets from multiple nodes in a time division manner.
(3) The MAC layer consists of a protocol that packetizes the power transmission interval, detects and avoids collisions of power transmission packets from multiple nodes by carrier sense, and retransmits them, and a protocol that allocates time slots for transmission packets from multiple nodes in a time division manner. It has both protocols.
(4) The MAC layer has a protocol for phase-combining transmission packets from multiple nodes and maximizing received power.
(5) The MAC layer has a CDMA protocol that simultaneously receives power from a plurality of power transmission nodes (power supply nodes) at one power receiving node using orthogonal or pseudo-orthogonal codes.

A case of multipoint-to-one power transmission and a case of one-to-one power transmission will be described below.
(multipoint-to-one power transmission)
FIG. 46 shows a schematic configuration for receiving power from a plurality of power transmitters. When power is supplied from multiple power transmitters, it is necessary to avoid reduction in received power due to cancellation of multiple microwaves at the receiving end of the power receiving device or repeater receiving power. Wave phase adjustment is required. In the present invention, time synchronization is performed in order to align the phases of microwaves of a plurality of power transmitters.

The present invention controls the microwave frequency of the power transmitter so that the time error between the two power transmitters falls within the maximum permissible time error and the phase difference between the two waves falls within the maximum permissible phase error by controlling the MAC layer. , to perform time synchronization.

The phase error Phase error is expressed by Phase error=2πfΔt, where f is the microwave frequency and Δt is the phase difference.

The time synchronization error is generally several tens of ns to several hundreds of ns, and a negative effect occurs when the phase difference between the two waves is 120 (deg) or more. As an example, when the maximum time error is 300 ns and the maximum allowable phase error is 100 (deg),
(5π/9) > 2πf 300ns
Using a microwave of about 1 MHz as the frequency f from the calculation of , an error in time synchronization can be avoided.

FIG. 47 shows power transmission from a plurality of antennas when power is supplied from a plurality of power transmitters, and FIG. 48 shows the positional relationship between a node (power receiving terminal) Rx and antennas Tx1 and Tx2. Here, a node (power receiving terminal) Rx is a power receiving terminal that receives power, and Tx1 and Tx2 are antennas that transmit power. Phase information is obtained by the following procedure.

(1) A node (power receiving terminal) Rx broadcasts a pilot signal (REF).
(2) Each antenna Tx1, Tx2 obtains the direction of arrival (DOA) of the pilot signal (REF) and broadcasts the information of (DOA).
(3) Each antenna Tx1, Tx2 calculates the distance between each antenna using (DOA) information broadcast from other antennas.
(4) Obtain the phase shift amount ΔΦ of the antenna closest to the node (power receiving terminal) Rx based on the distance between the antennas, and broadcast the phase shift amount ΔΦ to other antennas as Data (Ps).

The phase shift amount ΔΦ is represented by the following formula.

（３８）
ノード（受電端末）ＲxとアンテナＴx1，Ｔx2間の距離は以下の式で表される。

(38)
The distance between the node (power receiving terminal) Rx and the antennas Tx1 and Tx2 is expressed by the following equations.

（３９）

(39)

(one-to-one power transmission)
Here, we discuss the optimum beamwidth when there is an angular error between the main lobe of the drone and the antenna. FIG. 49 shows a state in which there is an error between the direction of the drone as seen from the antenna and the main lobe direction of the antenna. Angle errors include an azimuth angle Δθ and an elevation angle Δφ. Thus, the angular errors in the azimuth angle Δθ and the elevation angle Δφ between the main lobes of the drone and the antenna affect the power feeding efficiency to the drone.

According to the present invention, the power received by the antenna is expressed by the following equation based on the angle errors of the azimuth angle Δθ and the elevation angle Δφ.

（４０）
ここで、Ｇtはアンテナのゲイン、Ａrはアンテナの有効開口面積である。

(40)
Here, Gt is the gain of the antenna and Ar is the effective aperture area of the antenna.

On the other hand, the gain Gt of the antenna is expressed by the following equation using the azimuth angle Δθ and the elevation angle Δφ as variables.

（４１）

(41)

Therefore, the optimum beam width can be obtained by maximizing the gain Gt of the antenna based on the azimuth angle Δθ and elevation angle Δφ.

(simulation)
FIG. 50 is a simulation example of the optimum beam width, showing the optimum beam width with respect to the beam tilt angle and the angular deviation of the drone.

(Optimization of antenna directional beam)
Industrial unmanned aerial vehicles (UAVs) such as drones are known as mobile power receiving terminals at power receiving nodes. In particular, in the field of disaster investigation, studies are underway to improve the efficiency of rescue operations in the event of a disaster, such as grasping the damage situation using drone aerial photography and identifying the position of victims by mounting a UWB radar on the drone. One of the problems with drones is the flight time of drones. The flight time of a drone is related to the size of the battery and the mass of the drone, and the two are in a trade-off relationship.

In other words, the larger the battery, the more power it holds, but the more power it consumes as the overall mass of the drone increases. Currently, a system is used in which the drone automatically returns to the power supply point before the battery runs out, and supplies power at the power supply point. However, in consideration of efficiency in disaster countermeasures, it is desirable to supply power during flight. There is wireless power transmission (WPT) as a power supply method, and power supply efficiency in drones is a problem in applying microwave transmission as wireless power transmission.

In microwave transmission, power is supplied by irradiating a beam toward a receiving object. However, the drone may deviate from the range of the beam formed by the power transmission side due to the influence of the environment in the sky or hovering, in which case the power supply efficiency will be significantly reduced.

The goal is to improve the power supply efficiency by considering the characteristics of the drone, and to improve the power supply efficiency by considering the transmission distance to the drone and the estimation error and the beam width and its dynamic change. As the transmission distance to the drone increases, the impact of beam direction estimation errors decreases.

(Wireless power supply by phased array)
Power feeding using a phased array is known as a microwave power feeding method. Feeding by a phased array changes the direction of the main lobe by arranging the antenna elements in a fixed manner and giving each antenna element an excitation phase that makes the radiated electric fields of the antenna elements cophase in a specific direction. In power feeding to a moving target such as a drone, the target transmits a pilot signal, and the power transmission side aligns the direction of the main lobe with the direction of the power feeding target based on the received pilot signal.

Microwave power supply to a moving object such as a drone has a unique problem that it is necessary to consider the movement of the drone. The existing power feeding method radiates power with a constant beam width, so it is necessary to narrow the beam width in order to improve the power feeding efficiency. However, if the beam width is made too narrow, the movement of the drone may cause the drone to deviate from the main lobe. In addition, if the beam width is widened so that the main lobe can always catch the movement of the drone, the beam width becomes excessively wide, making it difficult to improve the power supply efficiency.

(Angle error with beam tilt angle due to movement of drone)
There is an angular error between the beam tilt angle of the directional characteristics of the array antenna and the drone, and there are mainly the following three factors for the error.

(1) Error in Phase Control of Array Antenna In beam forming in an array antenna, the main beam can be directed in a specific direction by using phase shifters and amplifiers. However, as the direction in which the main beam is directed approaches ±90° with respect to the normal direction of the antenna surface, an error occurs with respect to the actual direction.

(2) Motion associated with drone attitude control When the drone is stationary, if attitude control is performed against external influences such as wind, the drone will move and cause positional fluctuations, affecting the angle error. This effect depends on the size of the drone.

(3) Movement of the drone itself from the time the pilot signal is transmitted to the time power is supplied It varies with time plus the propagation time of the power signal, and this time affects the angle error as a delay time.

(Evaluation index)
Power supply efficiency is used as an evaluation index for the directivity characteristics of an array antenna. However, the power supply efficiency is expressed as the product of the power transfer efficiency (PTE) and the RE-DC (high frequency-direct current) conversion efficiency (PCE). is equal to the power transfer efficiency. Under these conditions, the power supply efficiency is expressed by the following equation.

（４２）

(42)

(Beam width considering the movement of the drone)
A beam width that maximizes the expression (42) with respect to the beam tilt angle of the directivity characteristics of the array antenna and the angle error between the drones is obtained. Here, with respect to the angle error between the beam tilt angle and the drone, the beam width that maximizes the power supply efficiency represented by Equation (42) is the optimum beam width, and the gain Gt is maximized with respect to the angle error. Obtain the beam width θHP.

In addition, both the transmission distance and the angular error of the beam tilt angle are factors that affect the movement of the drone. A simple pendulum model such as 51 is used. In FIG. 51, Δθ is the angle error when the drone is viewed from one antenna element of the array antenna, D is the distance between the antenna element and the drone, and x is the deviation distance between the main lobe of the antenna element and the drone.

The gain G of an array antenna is defined as G=4π/ _ΩA . Ω _A is the beam solid angle,
dΩ=dA/r ² =sinθ・dθ・dφ
defined by
The beam solid angle ΩA is expressed by the following equation.

（４３）
Ｐn（θ，φ）は電力パターンを正規化したものである。

(43)
Pn(θ,φ) is the normalized power pattern.

Equation (43) can be approximated as follows.

（４４）
式（４４）は、ビーム立体角Ω_Ａは、ビーム幅θHPと仰角φの幅φHPとの積で表され、ビーム幅θHPによって近似的に指向性利得が求められることを示している。

(44)
Equation (44) indicates that the beam solid angle _ΩA is expressed by the product of the beam width θHP and the width φHP of the elevation angle φ, and that the beam width θHP can be used to approximately obtain the directivity gain.

Next, when the main lobe of the directivity pattern is approximated by a quadratic curve from the maximum gain and beam width, the gain G(θ) with respect to the angular error Δθ is expressed by the following equation.

（４５）

(45)

The beam width θHP that maximizes the expression (45) is expressed by the following expression.

（４６）

(46)

（４７）

(47)

(system flowchart)
The angle error from the beam tilt angle due to the movement of the drone changes depending on the transmission distance D. Assuming that the amount of movement of the drone is a certain average value Δx, the angle error Δθ with respect to the center of the main lobe is expressed by the following equation.

（４８）
式（４８）は、伝送距離Ｄが大きい場合、ビームチルト角とドローンとの角度誤差Δθが小さくなるのでビーム幅θHPを狭くしてもドローンがメインローブから外れる確率は低くなることを示している。

(48)
Equation (48) indicates that when the transmission distance D is large, the angle error Δθ between the beam tilt angle and the drone becomes small, so even if the beam width θHP is narrowed, the probability that the drone deviates from the main lobe becomes low. .

The drone transmits a pilot signal, the arrival direction of the pilot signal of the drone is estimated by two power transmitters, and the distance to the drone is measured. The power supply efficiency is improved by changing the beam width in consideration of the distance measured and the amount of movement of the drone. In addition, the transmitter designs the optimal directivity by narrowing the beam emitted from the antenna of the transmitter for the receiver (power supply target) that moves and swings like a drone. This directivity optimization improves power receiving efficiency by widening the beam width according to the vibration dispersion in which the position is dispersed due to the vibration of the power receiver (power supply target).

FIG. 52 shows a flowchart of beamforming according to the present invention.
(1) The drone transmits a pilot signal (REF).
(2) The array antenna obtains the direction of arrival (DOA) of the pilot signal (REF) by the MUSIC method.
(3) The array antenna uses direction of arrival (DOA) information to measure the distance between the array antenna and the drone by triangulation.
(4) adjust the beam width of the array antenna based on the distance;
(5) Form a beam and transmit power to the drone.

(Simulation evaluation)
A simulation evaluation of the optimum beam width is shown. In the following, two simulation evaluations are shown for Equation (47) of the optimum beam width, one in consideration of wind and vibration due to attitude control, and the other in consideration of movement in the delay time. The specifications of the transmitter and receiver in the simulation are as follows.

（送電機の諸元）

(Specifications of power transmitter)

（受電機の諸元）
なお、ここでは、マルチパスによる影響はないものとし、ドローンに搭載する受電アンテナは等方性アンテナとする。また、所望波がアンテナ面の法線方向に対して角度をもつ場合、各受電アンテナにおいて入力信号に位相差が生じることにより合成した出力信号の振幅が小さくなることを考慮して、所望波はアンテナ面に対して垂直に入射するものと仮定する。

(Specifications of receiving power)
In this case, it is assumed that there is no influence of multipath, and the power receiving antenna mounted on the drone is an isotropic antenna. In addition, when the desired wave has an angle with respect to the normal direction of the antenna surface, considering that the amplitude of the combined output signal becomes small due to the phase difference between the input signals at each power receiving antenna, the desired wave is It is assumed that the incident light is perpendicular to the antenna plane.

(optimal beam width)
FIG. 53 shows the simulation result of the beam width maximizing the power supply efficiency shown by the equation (42) and the optimum beam width by the approximation of the equation (48) when the transmission distance is changed. It shows that the optimum beam width increases with the movement of the drone when the transmission distance is short, and the optimum beam width narrows as the transmission distance increases. The beam width in these specifications is 3.4 to 38 (deg). Note that in the simulation of FIG. 53, the amount of movement x of the drone is 0.9 (m).

(Optimal beam width considering the amount of movement of the drone)
Equations (47) and (48) show that the optimum beam width θHP is determined by the average moving amount x and transmission distance D of the drone. FIG. 54 shows the relationship between the optimum beam width and the amount of movement of the drone considering the angle error when the amount of movement x of the drone is 0.5 m, 0.8 m, and 1.0 m.

The characteristics considering the deviation of the drone when it is stationary are shown. There are two angle errors between the drone and the beam tilt angle: an error in the angle of arrival due to movement of the drone and an error due to the followability of the array antenna.

Regarding the error associated with the estimation of the angle of arrival, if the number of antenna elements is sufficiently large, there is almost no error even if the error approaches ±90° with respect to the direction perpendicular to the antenna surface. There are two main factors: movement due to the wind and movement in the delay time. Here, the movement of the drone when it is stationary is assumed to move vibratingly with respect to the beam tilt angle in consideration of movement due to wind or the like. FIG. 55 shows a moving state associated with attitude control against the wind when the drone is in a stationary state.

The characteristics of the simulation considering the movement due to wind etc. are as follows.

FIG. 56 shows the power supply efficiency when the drone, which was about to stand still, moved due to wind and attitude control at each transmission distance. FIG. 56 compares the optimum beamwidth, the narrowest beamwidth in the simulation, and the beamwidth where the drone is always in the main lobe. Drone movement due to wind etc. is assumed to be on an arc to consider the effect of angle only.

The characteristics shown in FIG. 56 show the beam widths of 3.4 [deg], 20 [deg], and the optimum beam width according to the present invention in order from the lowest power feeding efficiency, indicating the effectiveness of the optimum beam width. there is Since the effect of the angle due to the movement of the drone decreases as the transmission distance increases, in this case, the performance is similar to the case of narrowing the beam width by the existing method.

(optimal beam width considering drone movement at propagation delay)
FIG. 57 shows the movement state of the drone depending on the delay time. The drone is expected to move after transmitting the pilot signal until it is powered, and a delay time occurs between the pilot signal and the power supply.

The characteristics of the simulation considering the delay time due to the movement of the drone itself are as follows.

FIG. 58 shows the power supply efficiency with respect to the average amount of movement of the drone. Since the beam tilt angle and the angle error of the drone are average values due to movement during the delay time, it is assumed that the obtained power supply efficiency is also an average value.

The characteristics shown in FIG. 58 show the beam widths of 3.4 [deg], 20 [deg], and the optimum beam width according to the present invention in descending order of power supply efficiency. A beam width that does not deviate from the main lobe even when the drone moves is used.

If the beam width is narrow, there is a high possibility that the drone will deviate from the main lobe, so the power supply efficiency will be lower than if the drone does not deviate from the main lobe.

In the present invention, the power feeding efficiency is improved by adaptively changing the beam width to the optimum beam width according to the transmission distance. Also, even with the optimum beam width of the present invention, the beam width becomes wider as the amount of movement of the drone increases, so the power supply efficiency exhibits performance close to that of the existing system.

According to wireless power transmission by microwave from a fixed base station to the drone, due to external factors such as wind and delay time due to the movement of the drone itself from the transmission of the pilot signal to the power supply, Deviations from the main lobe of the directivity pattern are to be expected.

The wireless power transmission system of the present invention aims to improve power supply efficiency by adaptively changing the beam width in consideration of the movement of the drone. In addition, the power supply efficiency is improved by approximately obtaining the beam width that maximizes the power supply efficiency with respect to the angular error between the beam tilt angle and the drone, and by adaptively changing the beam width.

It should be noted that the description in the above embodiment and modifications is an example of the DC pulse power supply device according to the present invention, and the present invention is not limited to each embodiment, and various modifications are made based on the gist of the present invention. are possible and are not excluded from the scope of the present invention.

The wireless power transmission system of the present invention can be applied to long-term use of drones for disaster relief, constant infrastructure management and home delivery, mobile devices such as mobile phones, and implantable medical devices such as capsule endoscopes. can be done.

1 transmitter 2 receiver 3 repeater 4 network 10 wireless power transmission 11 physical layer 12 MAC layer 13 network layer 14 application layer 15 evaluation index 20 rectenna 21 antenna 22 rectifier 22a matching circuit 22b diode 22c filter 30 load 100 wireless power transmission 101 Multihop relay 102 Wireless power supply control 103 Optimal power supply path 104 Security 105 Power supply efficiency 200 Wireless information transmission 201 Modulation/coding 202 Protocol 203 Routing 204 Security 205a S/N ratio 205b Communication channel capacity RS Power receiving terminal Rx (power receiving terminal) Node Tx1 , Tx2 Antenna

Claims (23)

A wireless power transmission system that wirelessly transmits power using microwaves,
A power transmitter serving as a power transmission source node that transmits power, a power receiver serving as a node that receives the transmitted power, and a plurality of repeaters serving as nodes that transfer power between the power transmitter and the power receiver. a physical layer of a first layer composed of each node of the power transmitter, the power receiver, and the repeater; and a second layer that controls wireless transmission of power of each node in the physical layer of the first layer. A MAC layer of and a network layer of the third layer,
In the physical layer of the first layer, the plurality of nodes form a network between the power transmitter and the power receiver via the nodes of the plurality of repeaters, and the network includes the power transmitter and the power receiver. A multi-hop relay that relays the relay and performs power transmission between the power receiver and the power receiver,
In the MAC layer of the second layer, each node of the physical layer of the first layer performs power supply control from the power receiver to the power transmitter by means of access control between nodes that controls the transfer of power between the nodes. can be,
In the network layer of the third layer, the power transmission efficiency and/or the interference level per hop of the power transferred between each node by the power transmitter in the multi-hop relay of the physical layer of the first layer is determined by each node. in the path between the power transmitter and the power receiver, the power supply path that maximizes the sum of the weights associated with the paths between the nodes is determined as the physical layer of the first layer. It selects the optimum power supply route from among the multiple power supply routes of the network
A wireless power transmission system characterized by: The optimum number of the repeaters forming the nodes in the physical layer of the first layer is the feed rate (1-exp(-Ar ² /(λ ² Di ² ))) sent by the distance attenuation between the repeaters. The logarithm is the number obtained by differential operation with the number of repeaters i (where Ar is the antenna aperture area of the repeater node, λ is the wavelength of the microwave, and Di is the repeater distance of the repeater).
The wireless power transmission system according to claim 1, characterized by: In the physical layer of the first layer, the optimal distance of the repeater in a multi-hop relay model with more than two repeaters is the feed rate (1 -exp (-At · Ar / (λ ² · Di ² ))) and the feed rate sent by the distance attenuation between the repeaters (1-exp (-Ar ² / (λ ² · Di ² ))), The amount of power supplied is expressed using

Regarding the relationship between the relay distance D1 and the total power transmission distance D obtained when the number of repeaters is one in the differential calculation of the relay distance of the logarithm of the power supply, the relationship between the relay distance D1 and the total power transmission distance D of the multi-hop relay model with more than two repeaters (In the above formula, PCE is the power conversion efficiency of the rectenna, LOSS is the loss of the relay node, At is the aperture area of the antenna of the power transmitter, and Ar is the is the antenna aperture area of the relay node, λ is the wavelength of the microwave, and m is the number of distance attenuations)
The wireless power transmission system according to claim 1 , characterized by: 2. The wireless power transmission system according to claim 1 , wherein said repeater amplifies received power and transmits the amplified power. The number of repeaters is the number that minimizes the total amplification amount of the sum of the power amplification amounts of the repeaters with respect to the amount of power required by the power receiver.
The wireless power transmission system according to claim 4, characterized by: The transmission frequency of the node is the phase of the direct wave determined from the distance between the repeaters and the frequency of the direct wave, and the phase of the ground reflected wave determined from the distance between the repeater and the ground and the frequency of the ground reflected wave. is the frequency at which the phase shift is within the setting range,
The phase shift between the direct wave and the ground-reflected wave is calculated based on the path difference between the direct wave and the ground-reflected wave, which is calculated based on the distance between repeaters, and the wavelength of the microwave.
The wireless power transmission system according to claim 1 , characterized by: The power receiver directly receives power from a plurality of power transmitters or receives power via a plurality of repeaters in many-to-one power transmission , the power transmitters or the plurality of repeaters transmit power by time synchronization , Align the phase of the microwave ,
The time synchronization is such that the time error Δt of the plurality of power transmitters falls within the maximum permissible time error, and the phase error of the two transmission waves falls within the maximum permissible phase error from the relationship of phase error = 2π · frequency · Δt. It is the control of the frequency that fits
The wireless power transmission system according to claim 1 , characterized by: In the many-to-one power transmission from the plurality of nodes to the receiving power,
The node is
A distance between the power receiving power and each node is obtained from the power receiving power based on the azimuth angle of each node, a phase shift amount between the power nodes in the power receiving power is obtained based on the distance, and power transmission is performed based on the phase shift. 2. The wireless power transmission system according to claim 1 , wherein phase is compensated to reduce cancellation of power due to phase shift in said power receiver . The power transmitter is
Gain Gt ( _ _{_} _ _{_} _ _ Δθ, ΔΦ)

Let _HP be the optimized beam width of the power transmission antenna of the power transmitter
The wireless power transmission system according to claim 1 , characterized by: The wireless power transmission system according to claim 1 , wherein in one-to-many power transmission in which power is transmitted from one power transmission source to a plurality of power receiving ends, the beam shape of the power transmitter is multi-beam. 2. The power transmitter has an antenna directivity that radiates beams from a single power transmitter to multiple receivers or beams from multiple power transmitters to a single receiver. A wireless power transfer system as described. The network layer comprises:
In the weight of the route, with a weight of 1 as a boundary, routing including active routing that performs active route selection by setting a weight of 1 or more and passive routing that performs passive route selection by setting a weight of less than 1 2. The wireless power transmission system according to claim 1 , wherein the routing optimizes a power supply route of the network. The wireless power transmission system according to claim 12 , wherein the passive routing sets weights less than 1 including negative weights for paths with interference and paths with reflectors . In the network layer,
The selection of the optimum power supply route that maximizes the sum of the weights is to select the optimum power supply route by the Dijkstra method using a weighted graph, and is represented by the product of the power transmission efficiency and the power conversion efficiency. Select the power supply path that minimizes the reciprocal of the power supply efficiency
The wireless power transmission system according to claim 1 , characterized by: In the network layer,
the receiver broadcasts a power supply request packet (EREG packet) containing position information;
the repeater rebroadcasts the power request packet (EREG packet);
The power transmitter obtains a distance between nodes based on position information included in the received power supply request packet (EREG packet), and acquires the power transmission efficiency based on the distance between nodes. Item 1. The wireless power transmission system according to item 1 . 16. The wireless power transmission according to claim 15 , wherein the power transmitter supplies power in a power packet obtained by packetizing power to a power receiver requesting power supply by the power supply request packet (EREG packet). system. The MAC layer is
In the access control of power transmission performed by each node between each node of the physical layer of the first layer, power transmission intervals of power transmission performed between the nodes are packetized, and power is packetized from the plurality of nodes . 2. The wireless power transmission system according to claim 1 , comprising a protocol for detecting and avoiding collision of packets by carrier sense and retransmitting said power packet . The MAC layer is
a protocol for allocating time slots in a time-division manner by information packets related to communication control in the access control of power transmission performed by each node between each node of the physical layer of the first layer;
2. The wireless power transmission system according to claim 1 , further comprising a protocol for performing time-series control for sending power packets in which power is packetized after said information packets . The MAC layer is
In the access control of power transmission performed between each node of the physical layer of the first layer by each node, a power transmission interval of power transmission performed between the nodes is packetized, and a collision of power packets from the plurality of nodes is a carrier . a protocol for sensing, avoiding and retransmitting said power packet ;
and a protocol for time-dividing information packets relating to communication control from the plurality of nodes, allocating time slots, and avoiding collisions between power packets obtained by packetizing supplied power and information packets. , The wireless power transmission system according to claim 1 . The MAC layer is
In the access control of power transmission performed by each node between each node of the physical layer of the first layer, a protocol for phase combining power packets obtained by packetizing power from the plurality of nodes and maximizing received power is provided.
The wireless power transmission system according to claim 1 , characterized by: A wireless power/information transmission system that wirelessly transmits power and information,
A power transmitter that constitutes a power transmission source node that transmits power, a power receiver that constitutes a node that receives the transmitted power, and a plurality of nodes that constitute a node that exchanges power and information between the power transmitter and the power receiver. A first layer physical layer composed of a repeater, each node of the power transmitter, the power receiver, and the repeater, and wireless transmission of power and information of each node in the first layer physical layer a layer 2 MAC layer for controlling transmission and a layer 3 network layer;
In the physical layer of the first layer, the plurality of nodes form a network between the power transmitter and the power receiver via the nodes of the plurality of repeaters, and the network includes the power transmitter and the power receiver . A multi-hop relay that relays power and information between the power receiver and the relay,
In the MAC layer of the second layer, each node of the physical layer of the first layer transmits power and information from the power receiver to the power transmitter by access control between nodes that controls power and information transfer between each node. Simultaneous multiplex transmission is performed,
In the network layer of the third layer, the power transmission efficiency and/or the interference level per hop of the power transferred between each node by the power transmitter in the multi-hop relay of the physical layer of the first layer is determined by each node. and the sum of the weights associated with the route between the nodes in the route between the power transmitter and the power receiver is set as the power supply efficiency of the power transmission route, and the physical layer of the first layer selecting the route with the maximum power supply efficiency from among the plurality of routes of the network as the optimum power transmission route,
In the multi-hop relay of the physical layer of the first layer, the signal-to-noise ratio (S/N ratio) between adjacent nodes is associated with the weight of the route, and the node in the route between the power transmitter and the power receiver Let the sum of the weights associated with the paths between be the path signal-to-noise ratio of the information transmission path,
A path that maximizes the path signal-to-noise ratio and/or communication path capacity is selected from among a plurality of paths in the network of the physical layer of the first layer as an optimum information transmission path, and power and information are simultaneously multiplexed. be transmitted
A wireless power/information transmission system characterized by: In the network layer,
The sum of the weights of the power transmission paths between the power transmitter and the power receiver and the sum of the weights of the information transmission paths between the power transmitter and the power receiver are the weights of the paths between the two nodes in the weighted graph. Dijkstra's algorithm, which finds the path that minimizes the sum of
In the MAC layer,
The wireless transmission of power is performed by power transmission using the amplitude of the carrier wave of the microwave, and the wireless transmission of information is performed by information transmission using the phase of the carrier wave of the microwave, whereby simultaneous multiplex transmission of power and information is performed. be done
The wireless power/information transmission system according to claim 21, characterized by: In the network layer,
The sum of the weights of the power transmission paths between the power transmitter and the power receiver and the sum of the weights of the information transmission paths between the power transmitter and the power receiver are the weights of the paths between the two nodes in the weighted graph. Dijkstra's algorithm, which finds the path that minimizes the sum of
In the MAC layer,
Simultaneous multiplex transmission of power and information is performed by performing on/off modulation and time division of the power packet obtained by packetizing the power, and performing time-series control of the time-divided power packet and the information packet of information communication. be beaten
22. The wireless power/information transmission system according to claim 21, characterized by:

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