WO2023228753A1 - Power reception device and control method - Google Patents

Abstract

A power reception device (20) comprises: an antenna (first antenna 21) for receiving a first electric wave and a second electric wave; a first circuit (first rectifier circuit 22) that converts the first electric wave to a first power and outputs the first power; an output unit (24) that uses the first power to output a first signal for causing the a power transmission device (10) to output the second electric wave; and a second circuit (second rectifier circuit 23) that converts the second electric wave from the power transmission device (10) to a second power and outputs the second power.

Description

Power receiving device and control method

This application relates to a power receiving device and a control method.

In recent years, wireless power using microwaves has been used as a power source for charging secondary batteries. Patent Document 1 describes a technology for suppressing overcharging by intermittently supplying charging current to the secondary battery after the battery voltage reaches the end-of-charge voltage when charging the secondary battery using radio waves. is disclosed.

Japanese Patent Application Publication No. 2018-11481

A microwave power transmission system transmits power by transmitting a specific signal such as a beacon from a power receiving device, and having the power transmitting device form a beam in the direction of the power receiving device. In such a system, a power source such as a battery is required because the power receiving device needs to transmit a specific signal before receiving power transmission from the power transmitting device. For this reason, in the conventional system, there was a need for the power transmitting device to grasp the position of the power receiving device without providing a power source.

A power receiving device according to one aspect includes: an antenna for receiving a first radio wave and a second radio wave; a first circuit that converts the first radio wave into first power and outputs the first power; The power transmission device includes an output unit that outputs a first signal for causing the power transmission device to output a second radio wave, and a second circuit that converts the second radio wave from the power transmission device into second electric power and outputs it.

A control method according to one aspect includes a first output step of converting a first radio wave received from an antenna for receiving a first radio wave and a second radio wave into a first electric power, and outputting the first electric power; a second output step of outputting a first signal for causing a power transmission device to output a second radio wave using the power transmission device; and a third output step of converting the second radio wave from the power transmission device into second electric power and outputting it. ,including.

FIG. 1 is a diagram for explaining an overview of a power transmission system using a power receiving device according to an embodiment. FIG. 2 is a diagram illustrating an example of a circuit configuration of a first rectifier circuit and a second rectifier circuit of the power receiving device illustrated in FIG. 1. FIG. 3 is a graph showing an example of rectification efficiency characteristics of the first rectifier circuit and the second rectifier circuit shown in FIG. 2. FIG. 4 is a diagram showing a modification of the rectifier circuit of the power receiving device. FIG. 5 is a diagram showing an example of the configuration of the power transmission device shown in FIG. 1. FIG. 6 is a diagram for explaining another example of a rectifying element used by the power receiving device. FIG. 7 is a diagram illustrating a configuration example of a power receiving device according to a modification of the embodiment. FIG. 8 is a diagram illustrating another configuration example of a power receiving device according to a modification of the embodiment. FIG. 9 is a diagram illustrating a configuration example of a power receiving device including three rectifier circuits.

A plurality of embodiments for implementing the power receiving device, control method, etc. according to the present application will be described in detail with reference to the drawings. Note that the present invention is not limited to the following explanation. Furthermore, the constituent elements in the following description include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. In the following description, similar components may be denoted by the same reference numerals. Furthermore, duplicate explanations may be omitted.

FIG. 1 is a diagram for explaining an overview of a power transmission system using a power receiving device according to an embodiment. A system 1 shown in FIG. 1 includes, for example, a wireless power transmission system capable of microwave transmission type (space transmission type) wireless power transmission. Wireless power transmission is a mechanism that allows power to be transmitted without using cables or plugs, for example. The microwave transmission type system 1 uses radio waves (microwaves) for energy transmission, so it uses a narrow frequency band and non-modulated waves. For example, the system 1 transmits power in multiple frequency bands. For example, in Japan, the plurality of frequency bands include a 920 MHz band, a 2.4 GHz band, a 5.7 GHz band, and the like. In this embodiment, the system 1 makes it possible to improve power supply efficiency suitable for the situation and ensure safety at the same time. The system 1 can be applied to, for example, space solar power generation. Note that in the wireless power transmission system according to the embodiment of the present disclosure, the frequency band of the radio waves used is not limited to the above-mentioned microwaves, but the wavelength of the radio waves may include radio waves with a wide range of wavelengths from several meters to several pm. You may use it.

In the example shown in FIG. 1, the system 1 includes a power transmitting device 10 and a power receiving device 20. The power transmission device 10 is a device that transmits power wirelessly in the system 1. The power transmission device 10 is a device capable of transmitting radio waves for power supply. As the power transmission device 10, for example, a WPT (Wireless Power Transmission) power transmission device can be used. The power transmission device 10 is configured with an adaptive array antenna, and by adjusting the amplitude and phase of each antenna element, the direction and irradiation range of the power feeding beam can be arbitrarily set. For example, the power transmission device 10 performs directivity control by multiplying each antenna element by a weighting coefficient, and transmits the electric wave 2000 for power feeding. Directivity control means, for example, controlling the relationship between the radiation direction and radiation intensity of the radio waves 2000. Thereby, the power transmission device 10 emits radio waves 2000 in a radiation pattern having radiation directivity. The radio wave 2000 emitted by the power transmission device 10 includes a main lobe 2100 indicating a main component beam with strong electromagnetic intensity, and a side lobe 2200 indicating a beam other than the main lobe 2100. The side lobe 2200 indicates a beam that heads in a different direction from the main lobe 2100 and has a weaker electromagnetic intensity than the main lobe 2100.

[Configuration of power receiving device]
The power receiving device 20 is a power-supplied device in the system 1 that receives electric waves for power supply and obtains power. Power receiving device 20 outputs the power received from power transmitting device 10 to load 26 . The load 26 includes, for example, mechanical equipment, IoT (Internet of Things) sensors, electronic equipment, lighting equipment, and the like. In this embodiment, the power receiving device 20 has a device configuration that does not require a power source such as a battery.

A WPT power receiving device can be used as the power receiving device 20. Power receiving device 20 includes a first antenna 21 , a first rectifier circuit 22 , a second rectifier circuit 23 , an output section 24 , a second antenna 25 , and a load 26 .

The first antenna 21 is electrically connected to a first rectifier circuit 22 and a second rectifier circuit 23. The first antenna 21 is a power receiving antenna that can receive radio waves 2000 from the power transmitting device 10. For example, a patch antenna, a dipole antenna, a parabolic antenna, etc. can be used as the first antenna 21. The first antenna 21 outputs the received radio wave signal to the first rectifier circuit 22 and the second rectifier circuit 23 .

The first rectifier circuit 22 is electrically connected to the output section 24. The first rectifier circuit 22 efficiently converts a first high frequency signal having a first electromagnetic strength among radio waves received by the first antenna 21 into direct current. The first high frequency signal includes, for example, a high frequency signal that is necessary for the power receiving device 20 to output the specified signal 3000 and becomes the input power of the rectifier circuit. The first high frequency signal includes, for example, a signal indicating a beam of a side lobe 2200 of the radio wave 2000. A configuration example of the first rectifier circuit 22 will be described later. The first rectifier circuit 22 outputs a DC current (first power) obtained by converting the first high frequency signal to the output section 24 . The first rectifier circuit 22 is an example of a first circuit. The radio wave including the first high frequency signal is an example of the first radio wave.

The second rectifier circuit 23 is electrically connected to the load 26. The second rectifier circuit 23 converts, of the radio waves received by the first antenna 21, a second high frequency signal having a second electromagnetic intensity stronger than the first electromagnetic intensity into direct current. The second high frequency signal includes, for example, a high frequency signal that is necessary to operate the load 26 of the power receiving device 20 and becomes the input power of the rectifier circuit. The second high frequency signal includes, for example, a signal indicating the main lobe 2100 beam of the radio wave 2000. The second rectifier circuit 23 does not convert the first high frequency signal of the first electromagnetic strength described above. A configuration example of the second rectifier circuit 23 will be described later. The second rectifier circuit 23 outputs a DC current (second power) obtained by converting the second high-frequency signal to the load 26 . The load 26 operates using the power output from the second rectifier circuit 23. That is, the first rectifier circuit 22 has the highest conversion efficiency when converting the first high frequency signal with the first electromagnetic strength into direct current, and the second rectifier circuit 23 converts the second high frequency signal with the second electromagnetic strength into direct current. In the case of conversion, the conversion efficiency may be the highest. The second rectifier circuit 23 is an example of a second circuit. The radio wave including the second high frequency signal is an example of the second radio wave.

The output section 24 is electrically connected to the second antenna 25. The output unit 24 uses the power output from the first rectifier circuit 22 to output (send) a specified signal 3000. The regulation signal 3000 includes, for example, a beacon, a pilot signal, and the like. The output unit 24 generates a prescribed signal 3000 for supply route estimation using, for example, a transmitting circuit, and outputs the prescribed signal 3000 to the second antenna 25.

The second antenna 25 is an antenna that can radiate radio waves containing the signal output by the output section 24. As the second antenna 25, for example, a patch antenna, a dipole antenna, a parabolic antenna, etc. can be used. The second antenna 25 radiates radio waves containing the signal output by the output section 24. In this embodiment, the power receiving device 20 includes the first antenna 21 and the second antenna 25, but the first antenna 21 and the second antenna 25 may be implemented by one antenna.

The load 26 is, for example, a battery, a storage battery, a capacitor, a CPU (Central Processing Unit), sensors such as a thermometer, hygrometer, or vibration meter, an imaging device such as a camera, an antenna, or the like. Examples include electric lights, drones, machine tools, etc., but the load 26 is not limited to these, and any appropriate device may be used as the load 26.

The functional configuration example of the power receiving device 20 according to the present embodiment has been described above. Note that the above configuration described using FIG. 1 is just an example, and the functional configuration of the power receiving device 20 according to the present embodiment is not limited to the example. The functional configuration of the power receiving device 20 according to the present embodiment can be flexibly modified according to specifications and operation.

Next, an example of the operation of the system 1 will be described. In scene C1, the power transmission device 10 performs directivity control by multiplying each antenna by a weighting coefficient, and radiates radio waves 2000 for power feeding. Directivity control means, for example, controlling the relationship between the radiation direction and radiation intensity of the radio waves 2000. Thereby, the power transmission device 10 emits radio waves 2000 in a radiation pattern having radiation directivity. In the example shown in FIG. 1, the power transmitting device 10 emits radio waves 2000 in which a main lobe 2100 is directed in a direction different from that of the power receiving device 20, and a side lobe 2200 is directed in a direction near the power receiving device 20. A side lobe 2200 beam of the radio wave 2000 emitted by the power transmitting device 10 is directed toward the power receiving device 20 .

The power receiving device 20 receives the side lobe 2200 beam of the radio wave 2000 emitted by the power transmitting device 10 using the first antenna 21 as a first high frequency signal with a first electromagnetic intensity. The power receiving device 20 converts the received first high-frequency signal into a direct current using the first rectifier circuit 22 and outputs the DC current to the output unit 24 (first output step). The power receiving device 20 uses the direct current to output the specified signal 3000 (first signal) for causing the power transmitting device 10 to output the second radio wave, thereby transmitting the radio wave including the specified signal 3000 to the first signal. 2 antenna 25 (second output step). A beam of radio waves emitted by the power receiving device 20 is directed toward the power transmitting device 10 . Note that the power receiving device 20 does not convert the first high frequency signal into a direct current at the second rectifier circuit 23 because the received first high frequency signal is weaker in strength than the second electromagnetic strength.

Upon receiving the specified signal 3000, the power transmitting device 10 estimates the position of the power receiving device 20 based on the specified signal 3000. For example, the power transmission device 10 estimates the reception response vector by comparing the received specified signal 3000 and a known reference signal. The power transmitting device 10 calculates a weighting coefficient for transmission with respect to the estimated position of the power receiving device 20 (reception response vector).

In scene C2, the power transmitting device 10 performs directivity control by multiplying a plurality of antenna elements by a weighting coefficient, and radiates radio waves 2000 of a transmission signal for power feeding toward the power receiving device 20. The power transmitting device 10 emits a radio wave 2000 of a transmission signal in which a main lobe 2100 is directed toward the power receiving device 20 and a side lobe 2200 is directed in a direction different from the power receiving device 20 .

The power receiving device 20 receives the beam of the main lobe 2100 of the radio wave 2000 emitted by the power transmitting device 10 with the first antenna 21 as a second high frequency signal with a second electromagnetic intensity. The power receiving device 20 converts the received second high-frequency signal into a DC current using the second rectifier circuit 23, and outputs (supplies) the DC current to the load 26 (third output step). Thereby, in the power receiving device 20, the load 26 operates using the DC power outputted by the second rectifier circuit 23. Note that in the power receiving device 20, most of the received second high frequency signal appears as a DC output of the second rectifier circuit 23.

As described above, the power receiving device 20 converts the first high frequency signal with the first electromagnetic strength into direct current with the first rectifier circuit 22, and converts the second high frequency signal with an intensity stronger than the first electromagnetic strength into direct current with the second rectifier circuit 23. Convert to The power receiving device 20 radiates the prescribed signal 3000 from the second antenna 25 using the power output from the first rectifier circuit. Thereby, the power receiving device 20 can radiate the specified signal 3000 with the second antenna 25 using the power obtained by converting the first high frequency signal even if the main lobe 2100 of the power transmitting device 10 is not directed toward the power receiving device 20. As a result, the power receiving device 20 can make the power transmitting device 10 grasp the position of the power receiving device 20 without having a power source or the like that operates the output unit 24 .

The power receiving device 20 can convert a second high-frequency signal having an intensity stronger than the first electromagnetic intensity into electric power for the second rectifier circuit 23 to drive the load 26. Thereby, the power receiving device 20 receives a high-frequency signal with large power from the power transmitting device 10, and can obtain a large DC output from the second rectifier circuit 23. As a result, the power receiving device 20 can obtain wireless power from the power transmitting device 10, which has the position of the power receiving device 20, without being provided with a power source.

In the example shown in FIG. 1, the system 1 is configured to control power received by the first antenna 21 of the power receiving device 20 when the power feeding beam of the power transmitting device 10 is not correctly irradiated to the power receiving device 20, or when the power feeding beam is irradiated over a wide range. The case where is small is shown. At this time, in the power receiving device 20, most of the received power appears as a DC output of the first rectifier circuit 22, drives the output section 24, and the specified signal 3000 is transmitted from the second antenna 25. In system 1, when prescribed signal 3000 is received by power transmitting device 10, power transmitting device 10 emits radio waves 2000 including a beam with a narrowed irradiation range toward power receiving device 20. In the system 1, when the first antenna 21 of the power receiving device 20 receives this beam, most of the received power appears as a DC output of the second rectifier circuit 23, and wireless power is supplied to the load 26. As a result, the system 1 can grasp the position of the power receiving device 20 that does not include a power source simply by the power transmitting device 10 outputting a transmission signal for power supply, so the power transmitting device 10 can manage the position of the power receiving device 20 in advance. This eliminates the need for this, allowing flexibility in the arrangement of the device.

FIG. 2 is a diagram showing an example of the circuit configuration of the first rectifier circuit 22 and the second rectifier circuit 23 of the power receiving device 20 shown in FIG. 1. As shown in FIG. 2, the first rectifier circuit 22 and the second rectifier circuit 23 are single shunt type rectifier circuits. A single-shunt type rectifier circuit consists of one diode and a λ/4 line, and has relatively good efficiency characteristics at high frequencies.

The first rectifier circuit 22 includes a diode 221, a λ/4 line 222, and a capacitor 223. The diode 221 has an anode grounded and a cathode electrically connected to the first antenna 21 . The λ/4 line 222 is configured with a line having a length corresponding to a quarter wavelength of the fundamental wave of the first high frequency signal received by the first antenna 21. One end of the λ/4 line 222 is electrically connected to the cathode of the diode 221, and the other end is electrically connected to one end of the capacitor 223 and the output section 24. The other end of the capacitor 223 is grounded.

The second rectifier circuit 23 includes a diode 231, a λ/4 line 232, and a capacitor 233. The diode 231 has an anode grounded and a cathode electrically connected to the first antenna 21 . The λ/4 line 232 is configured with a line having a length corresponding to a quarter wavelength of the fundamental wave of the second high frequency signal received by the first antenna 21. One end of the λ/4 line 232 is electrically connected to the cathode of the diode 231, and the other end is electrically connected to one end of the capacitor 233 and the load 26. The other end of the capacitor 233 is grounded.

In the following description, the voltage of the microwave supplied from the first antenna 21 to the input terminals of the first rectifier circuit 22 and the second rectifier circuit 23 will be referred to as a supply voltage. The DC voltage output from the first rectifier circuit 22 and the second rectifier circuit 23 is referred to as an output voltage.

In a known rectifier circuit, when the input power is increased, the input voltage becomes larger than the forward voltage Vf of the diode, so the conversion efficiency increases to a certain extent, but as the breakdown voltage approaches the breakdown voltage Vb, the reverse current increases. Flow conversion efficiency decreases. Therefore, in the rectifier circuit, the position of the efficiency peak point differs depending on the characteristics (Vf and Vb) of the diode.

The power receiving device 20 according to the present embodiment utilizes the difference in characteristics between two types of rectifier elements with different characteristics, that is, the diode 221 and the diode 231. The power receiving device 20 includes a first rectifier circuit 22 that efficiently converts a weak first high frequency signal into direct current, and a second rectifier circuit 23 that efficiently converts a second high frequency signal stronger than the first high frequency signal into direct current. It constitutes the rectifier circuit of the grid.

FIG. 3 is a graph showing an example of the rectification efficiency characteristics of the first rectifier circuit 22 and the second rectifier circuit 23 shown in FIG. 2. In FIG. 3, the horizontal axis indicates input power [dBm], and the vertical axis indicates the ratio of rectified DC power to input power, that is, rectification efficiency [%].

It is the characteristics of the diode that is the rectifier element that determines the efficiency and input/output characteristics of converting a high frequency signal into DC power in a rectifier circuit. The example shown in FIG. 3 shows the difference in rectification efficiency characteristics between two different types of diodes 221 and 231.

As shown in graph G2, the second rectifier circuit 23 equipped with the diode 231 has almost no output when the input power is 0 dBm or less. The first rectifier circuit 22 equipped with the diode 221 can obtain an output even when the input power is 0 dBm or less, as shown in graph G1. That is, the weak first high frequency signal includes a high frequency signal whose input power is 0 dBm or less. The efficiency characteristics of the first rectifier circuit 22 and the second rectifier circuit 23 reverse when the input power reaches 17 dBm, and the efficiency of the second rectifier circuit 23 becomes good in a high power region exceeding 20 dBm.

Therefore, the power receiving device 20 according to the present embodiment can drive the output section 24 and transmit the specified signal 3000 by using the output of the first rectifier circuit 22 when receiving weak power of about 0 dBm. Thereafter, when the power receiving device 200 receives the power feeding beam (second high frequency signal) of 17 dBm or more transmitted by the power transmitting device 10 in response to receiving the specified signal 3000, the second rectifier circuit 23 can supply a large output to the load 26. .

[Modified example of rectifier circuit]
Although the power receiving device 20 described above uses a single shunt type rectifier circuit as the first rectifier circuit 22 and the second rectifier circuit 23, the present invention is not limited thereto. For example, in the power receiving device 20, the first rectifier circuit 22 and the second rectifier circuit 23 may use different types of rectifier circuits. For example, the power receiving device 20 can use a rectifier circuit called a double shunt type. A double shunt rectifier circuit functions as a voltage doubler rectifier circuit, and is therefore used in applications that require a relatively high output voltage.

FIG. 4 is a diagram showing a modification of the rectifier circuit of the power receiving device 20. As shown in FIG. 4, the power receiving device 20 includes a first antenna 21, a first rectifier circuit 22-1, a second rectifier circuit 23, an output section 24, a second antenna 25, and a load 26. Be prepared. That is, the power receiving device 20 uses a double shunt method in the first rectifier circuit 22-1, which is a low power rectifier circuit, in order to obtain the voltage required by the output section 24 that outputs the specified signal 3000 with as little input power as possible. However, the second rectifier circuit 23, which is a high power rectifier circuit, utilizes the single shunt method described above in order to obtain high efficiency.

The first rectifier circuit 22-1 is electrically connected to the first antenna 21 at one end and to the output section 24 at the other end. The first rectifier circuit 22-1 efficiently converts a first high-frequency signal having a first electromagnetic strength among radio waves received by the first antenna 21 into direct current. The first rectifier circuit 22-1 is. It has a diode 221, a diode 224, and a capacitor 223. The diode 221 has an anode grounded and a cathode electrically connected to the first antenna 21 . The diode 224 has an anode electrically connected to the first antenna 21 and the cathode of the diode 221, and a cathode connected to one end of the capacitor 223 and the output section 24. The other end of the capacitor 223 is grounded.

In the example shown in FIG. 4, the power receiving device 20 utilizes the difference in characteristics between the first rectifier circuit 22-1 and the second rectifier circuit 23, which have two types of different systems. The power receiving device 20 includes a first rectifier circuit 22-1 that efficiently converts a weak first high frequency signal into direct current, and a second rectifier circuit 23 that efficiently converts a second high frequency signal stronger than the first high frequency signal into direct current. It constitutes two systems of rectifier circuits.

The power receiving device 20 converts a first high frequency signal with a first electromagnetic strength into direct current using the first rectifier circuit 22-1, and converts a second high frequency signal with a stronger strength than the first electromagnetic strength into direct current using the second rectifier circuit 23. Convert. The power receiving device 20 radiates the prescribed signal 3000 from the second antenna 25 using the power output from the first rectifier circuit 22-1. Thereby, even if the strength of the radio waves 2000 received by the first antenna 21 is weak, the power receiving device 20 can transmit the specified signal 3000 using the power obtained by converting the first high frequency signal. As a result, the power receiving device 20 can make the power transmitting device 10 grasp the position of the power receiving device 20 without being provided with a power source.

[Configuration of power transmission device]
FIG. 5 is a diagram showing an example of the configuration of the power transmission device 10 shown in FIG. 1. As shown in FIG. 5, the power transmission device 10 includes an antenna 11, a transmission signal generation section 12, a transmission section 13, a reception section 14, an estimation section 15, a storage section 16, and a control section 17. . The control section 17 is electrically connected to the transmission signal generation section 12, the transmission section 13, the reception section 14, the estimation section 15, the storage section 16, and the like. In this embodiment, in order to simplify the explanation, a case will be described in which the power transmission device 10 includes the antenna 11 having four antenna elements 11A, but the number of antenna elements 11A is not limited to this.

The antenna 11 has a configuration that allows directivity control (beamforming). The antenna 11 is an antenna array including a plurality of antenna elements 11A. For example, in the antenna 11, each of the plurality of antenna elements 11A emits the same radio wave, and by adjusting the phase and power intensity of each, the radio waves can be strengthened in a specific direction and canceled out and weakened in another direction. The configuration is possible. The antenna 11 emits radio waves 2000 containing a transmission signal, and receives radio waves containing a signal from the power receiving device 20. Antenna 11 supplies the received signal to receiving section 14 .

The transmission signal generation unit 12 generates a transmission signal for power supply by converting the current to be transmitted to the power receiving device 20 into radio waves. The transmission signal is a signal for transmitting radio waves that can supply power. The transmission signal generation unit 12 generates a transmission signal by converting current from a power source (not shown) into radio waves at a transmission frequency. The power source includes, for example, a commercial power source, a DC power source, a battery, and the like. The transmission signal generation section 12 supplies the generated transmission signal to the transmission section 13.

The transmitter 13 is electrically connected to the plurality of antenna elements 11A of the antenna 11. The transmitter 13 causes the antenna 11 to radiate radio waves including a transmission signal for power feeding. The transmitter 13 radiates radio waves in a specific direction from the plurality of antenna elements 11A by applying weights corresponding to the beams that can be formed by the plurality of antenna elements 11A. The transmitter 13 applies the weights instructed by the controller 17 to the plurality of antenna elements 11A.

The receiving unit 14 is electrically connected to the plurality of antenna elements 11A of the antenna 11, the estimating unit 15, and the like. The receiving unit 14 extracts a received signal from the radio waves received from the power receiving device 20 via the antenna 11 . The received signal includes, for example, the above-mentioned regulation signal 3000 and the like. The receiving section 14 supplies the extracted received signal to the estimating section 15, the controlling section 17, and the like.

The estimation unit 15 estimates the radio wave propagation environment from the known regulation signal 3000 received from the power receiving device 20. The radio wave propagation environment includes, for example, a space in which radio waves are propagated between the power transmitting device 10 and the power receiving device 20. The estimation unit 15 estimates, for example, the state of radio wave propagation in space. The radio wave propagation situation includes, for example, an environment in which direct waves are dominant, a multipath-rich environment in which reflected waves occur, and other situations in which it is possible to identify. The estimation unit 15 estimates a reception response vector (terminal direction of arrival) from the received signal. The estimation unit 15 estimates the reception response vector by, for example, comparing the known regulation signal 3000 included in the received signal with a known reference signal. For example, the estimation unit 15 estimates the propagation environment using the reception level, sensitivity, reception response vector, reference propagation model, machine learning program, etc. of the specified signal 3000 in order to understand the situation of radio wave propagation in space. do. For example, when the loss of the received specified signal 3000 is smaller than the determination threshold, the estimation unit 15 estimates an environment where direct waves are dominant and a radio wave propagation environment. For example, the estimation unit 15 estimates the multipath rich environment and the radio wave propagation environment when the loss of the received specified signal 3000 is equal to or greater than the determination threshold. The estimation unit 15 supplies the estimation result based on the prescribed signal 3000 to the control unit 17.

The storage unit 16 can store programs and data. The storage unit 16 may include any non-transitory storage medium such as a semiconductor storage medium and a magnetic storage medium. The storage unit 16 may include a combination of a storage medium such as a memory card, an optical disk, or a magneto-optical disk, and a storage medium reading device. The storage unit 16 may include a storage device such as a RAM used as a temporary storage area.

The storage unit 16 can store weight data 161 and the like. The weight data 161 includes, for example, data indicating a plurality of weights (weighting coefficients) for adjusting the amplitude and phase of the signals radiated from the plurality of antenna elements 11A of the antenna 11 for each of the plurality of directivity patterns. The weight data 161 includes, for example, data indicating a combination of the plurality of antenna elements 11A corresponding to the directivity pattern.

The control unit 17 includes one or more arithmetic units. Examples of arithmetic devices include, but are not limited to, CPUs (Central Processing Units), SoCs (System-on-a-Chip), MCUs (Micro Control Units), FPGAs (Field-Programmable Gate Arrays), and coprocessors. Not done. The control unit 17 realizes processing related to various operations of the power transmission device 10 by causing a calculation device to execute a program.

Upon receiving the regulation signal 3000, the control unit 17 estimates the position of the power receiving device 20 based on the regulation signal 3000. For example, the control unit 17 estimates the reception response vector by comparing the received specified signal 3000 with a known reference signal. The control unit 17 refers to the weight data 161 and calculates a weighting coefficient for transmission with respect to the estimated position of the power receiving device 20. The control unit 17 performs directivity control by multiplying the plurality of antenna elements 11A by a weighting coefficient, and causes the radio waves 2000 of the power feeding transmission signal to be radiated toward the power receiving device 20. For example, the control unit 17 can perform directivity control by multiplying the plurality of antenna elements 11A by a weighting coefficient, and radiate the radio wave 2000 containing the first high-frequency signal of the first electromagnetic strength over a wide range. The control unit 17 can periodically or irregularly radiate radio waves over a wide area.

The functional configuration example of the power transmission device 10 according to the present embodiment has been described above. Note that the above configuration described using FIG. 5 is just an example, and the functional configuration of the power transmission device 10 according to the present embodiment is not limited to the example. The functional configuration of the power transmission device 10 according to this embodiment can be flexibly modified according to specifications and operation.

The power transmitting device 10 radiates radio waves 2000 including a first high frequency signal with a first electromagnetic strength directed over a wide range from the antenna 11 while the direction of the power receiving device 20 is unknown. Thereby, when the power receiving device 20 receives the radio wave 2000 with the first antenna 21 , the power receiving device 20 transmits the specified signal 3000 from the second antenna 25 using the DC output of the first rectifier circuit 22 . Then, the power transmitting device 10 estimates the position of the power receiving device 20 based on the prescribed signal 3000 received by the antenna 11, and emits radio waves 2000 including a transmission signal for power feeding toward the power receiving device 20. Thereby, when the power receiving device 20 receives the radio wave 2000 with the first antenna 21, the load 26 is operated by the DC output of the second rectifier circuit 23.

As described above, the system 1 can grasp the presence and direction of the power receiving device 20 by the power transmitting device 10 emitting radio waves 2000 over a wide range. As a result, the system 1 can efficiently irradiate the power supply beam in the direction of the power receiving device 20 without the power transmitting device 10 knowing in advance the position of the power receiving device 20 that is not equipped with a power source. Wireless charging is possible.

[Modified example of power receiving device]
FIG. 6 is a diagram for explaining another example of a rectifying element used by the power receiving device 20. In FIG. 6, the horizontal axis indicates input power [dBm], and the vertical axis indicates the ratio of rectified DC power to input power, that is, rectification efficiency [%]. FIG. 6 is a diagram in which a graph G3 is added to the graphs G1 and G2 of FIG. 3 described above.

As shown in FIG. 6, the power receiving device 20 can use a diode 291 having intermediate characteristics between the diode 221 and the diode 231 described above. For example, the diodes 221, 231, and 291 each have different input power at the rising edge and input power at which the rectification efficiency (output power) reaches its peak. Like the diode 221, the diode 291 can obtain an output even when the input power is 0 dBm or less, as shown in graph G3. The efficiency characteristics of the diode 221 and the diode 291 reverse when the input power reaches 12 dBm, and the efficiency of the second rectifier circuit 23 becomes good in a high power region exceeding 20 dBm. Therefore, the power receiving device 20 selects the combination of diodes 221, 231, and 291 based on the required power of the beacon transmission circuit of the output section 24 to be used and the power to be supplied to the load 26, thereby creating an optimal power transmission system. Can be configured. For example, by replacing the diode 231 of the second rectifier circuit 23 with a diode 291, the power receiving device 20 can cause the second rectifier circuit 23 to output even if the input power is 0 dBm or less.

The power receiving device 20 described above may be configured to combine the outputs of a plurality of rectifier circuits and supply the combined output to one load 26. FIG. 7 is a diagram illustrating a configuration example of a power receiving device 20 according to a modification of the embodiment. As shown in FIG. 7, the power receiving device 20 may be configured to electrically connect the first rectifier circuit 22 to the output section 24 and the load 26. Thereby, the power receiving device 20 can combine the outputs of the first rectifier circuit 22 and the second rectifier circuit 23 and output it to the load 26, so regardless of the magnitude of the input power of the high frequency signal received by the first antenna 21, Efficient power transmission can be achieved.

Although the power receiving device 20 described above has been described with respect to a case where the first rectifier circuit 22 and the second rectifier circuit 23 are switched to operate according to the characteristics of the rectifying element, the present invention is not limited to this. FIG. 8 is a diagram illustrating another configuration example of the power receiving device 20 according to a modification of the embodiment.

As shown in FIG. 8, the power receiving device 20 includes a first antenna 21, a first rectifier circuit 22, a second rectifier circuit 23, an output section 24, a second antenna 25, a load 26, and a monitoring section 27. and a switch 28. That is, the power receiving device 20 can have the monitoring unit 27 and the switch 28 added to its configuration.

The monitoring unit 27 monitors the converted voltage of the second high frequency signal received by the first antenna 21. In the example shown in FIG. 8, the monitoring unit 27 is provided between the second rectifier circuit 23 and the load 26, and monitors the converted voltage obtained by converting the signal by the second rectifier circuit 23. The monitoring unit 27 is electrically connected to the switch 28. The monitoring unit 27 outputs a switching signal to the switch 28 when the voltage converted by the second rectifier circuit 23 exceeds a certain value. The monitoring unit 27 does not output a switching signal to the switch 28 when the voltage converted by the second rectifier circuit 23 is below a certain value.

The switch 28 is configured to be able to switch between the first rectifier circuit 22 and the second rectifier circuit 23 that convert the high frequency signal. The switch 28 is an analog switch that is built into the branch line 20A that branches from the first antenna 21 to the first rectifier circuit 22, and can switch between input and cutoff of a signal to the first rectifier circuit 22. The switch 28 inputs a signal to the first rectifier circuit 22 when the output of the second rectifier circuit 23 does not exceed a certain value. The switch 28 cuts off the signal input to the first rectifier circuit 22 when the output of the second rectifier circuit 23 exceeds a certain value. In this embodiment, the switch 28 cuts off the signal input to the first rectifier circuit 22 in response to a switching signal from the monitoring section 27.

The power receiving device 20 has a first rectifier circuit 22 for small power and a second rectifier circuit 23 for high power connected in parallel, and the monitoring unit 27 converts the difference in received power into a voltage. The switch 28 can be switched by. Thereby, the power receiving device 20 can reduce the influence of the rectifier circuits on each other and further improve rectification efficiency by switching between two or more rectifier circuits having different rectification characteristics. Note that when the monitored voltage is low power, the power receiving device 20 does not need to cut off the second rectifier circuit 23 because the diode 231 of the second rectifier circuit 23 is cut off.

FIG. 9 is a diagram illustrating a configuration example of a power receiving device including three rectifier circuits. As shown in FIG. 9, the power receiving device 20-1 includes a first antenna 21, a first rectifier circuit 22, a second rectifier circuit 23, an output section 24, a second antenna 25, a load 26, and a second rectifier circuit 23. 3 rectifier circuit 29. The power receiving device 20-1 has a configuration in which a first rectifying circuit 22, a second rectifying circuit 23, and a third rectifying circuit 29 having three different rectifying characteristics are provided in parallel.

The first antenna 21 is electrically connected to a first rectifier circuit 22, a second rectifier circuit 23, and a third rectifier circuit 29. The first rectifier circuit 22 includes the diode 221 described above. The second rectifier circuit 23 includes the diode 231 described above. The third rectifier circuit 29 includes the diode 291 described above (see FIG. 6).

The third rectifier circuit 29 is electrically connected to the load 26. The third rectifier circuit 29 converts a third high frequency signal of a third electromagnetic intensity between the first electromagnetic intensity and the second electromagnetic intensity among the radio waves received by the first antenna 21 into direct current. The third rectifier circuit 29 outputs a DC current obtained by converting the third high frequency signal to the load 26 . The load 26 can operate using the power output from the third rectifier circuit 29. The load 26 can operate using power obtained by combining the power output from the third rectifier circuit 29 and the power output from the second rectifier circuit 23.

The power receiving device 20-1 can obtain high transmission efficiency over a wide range of input power by switching according to the input power of three rectifier circuits with different rectification characteristics or by configuring the outputs to be combined. .

Specific embodiments have been described to provide a complete and clear disclosure of the technology as claimed below. However, the appended claims should not be limited to the above-mentioned embodiments, but include all modifications and substitutions that can be created by a person skilled in the art within the scope of the basic matters presented in this specification. should be configured to embody a specific configuration. Those skilled in the art can make various changes and modifications to the contents of the present disclosure based on the present disclosure. Accordingly, these variations and modifications are included within the scope of this disclosure. For example, in each embodiment, each functional unit, each means, each step, etc. may be added to other embodiments so as not to be logically contradictory, or each functional unit, each means, each step, etc. of other embodiments may be added to other embodiments to avoid logical contradiction. It is possible to replace it with Further, in each embodiment, it is possible to combine or divide a plurality of functional units, means, steps, etc. into one. Further, each embodiment of the present disclosure described above is not limited to being implemented faithfully to each described embodiment, but may be implemented by combining each feature or omitting a part as appropriate. You can also do that. The method of the present disclosure may be implemented in a device including a CPU and a memory by the CPU executing a program stored in the memory.

1 System 10 Power transmission device 11 Antenna 12 Transmission signal generation unit 13 Transmission unit 14 Receiving unit 15 Estimating unit 16 Storage unit 17 Control unit 20, 20-1 Power receiving device 21 First antenna 22 First rectifier circuit 23 Second rectifier circuit 24 Output Section 25 Second antenna 26 Load 27 Monitoring section 28 Switch 29 Third rectifier circuit 221 Diode 222 λ/4 line 223 Capacitor 231 Diode 232 λ/4 line 233 Capacitor 2000 Radio wave 2100 Main lobe 2200 Side lobe 3000 Specified signal

Claims (8)

an antenna for receiving the first radio wave and the second radio wave;
a first circuit that converts the first radio wave into first electric power and outputs it;
an output unit that uses the first power to output a first signal for causing the power transmission device to output a second radio wave;
a second circuit that converts the second radio wave from the power transmission device into second electric power and outputs the second electric wave;
A power receiving device comprising: The power receiving device according to claim 1,
A power receiving device that combines outputs from the first circuit and the second circuit to output power capable of driving a load. The power receiving device according to claim 2,
a monitoring unit that monitors a converted voltage obtained by converting the received signal by the second circuit;
a switch capable of switching between the first circuit and the second circuit that converts a signal based on the conversion voltage;
A power receiving device comprising: The power receiving device according to claim 1,
The first circuit is a first rectifier circuit that converts the first radio wave into direct current. The power receiving device. The power receiving device according to claim 1,
The second circuit is a second rectifier circuit that converts the second radio wave into direct current. The power receiving device. The power receiving device according to claim 1,
The first circuit has the highest conversion efficiency when converting the first radio wave of the first power into direct current,
The second circuit has the highest conversion efficiency when converting the second radio wave of the second power into direct current. The power receiving device. The power receiving device according to claim 1,
A power receiving device that drives a load with the second power output from the second circuit. a first output step of converting the first radio wave received from the antenna for receiving the first radio wave and the second radio wave into first electric power and outputting the first electric power;
a second output step of outputting a first signal for causing the power transmission device to output a second radio wave using the first power;
a third output step of converting the second radio wave from the power transmission device into second power and outputting it;
A method for controlling a power receiving device including:

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