Power receiving device and control method

Abstract

To provide a power receiving device that causes a power transmitting device to grasp the position of the power receiving device without including a power supply.SOLUTION: For example, a power receiving device 20 comprises: an antenna (first antenna 21) for receiving a first radio wave and a second radio wave; a first circuit (first rectification circuit 22) that converts the first radio wave into first power and outputs the power; an output unit 24 for outputting, by using the first power, a first signal for causing a power transmitting device to output the second radio wave; and a second circuit (second rectification circuit 23) that converts the second radio wave from the power transmitting device into second power and outputs the power.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In recent years, wireless power using microwaves has been used as a power source for charging secondary batteries. Patent Document 1 discloses a technology for suppressing overcharging in charging a secondary battery using radio waves by intermittently supplying a charging current to the secondary battery after the battery voltage reaches the end-of-charge voltage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-11481 Summary of the Invention [Problem to be solved by the invention]

[0004] In a microwave power transmission system, a power receiving device transmits a specific signal, such as a beacon, and a power transmitting device transmits power by forming a beam in the direction of the power receiving device. In such a system, the power receiving device needs to transmit a specific signal before receiving power from the power transmitting device, which requires a power source, such as a battery. Therefore, in conventional systems, there is a need to enable the power transmitting device to determine the location of the power receiving device without having a power source. [Means for solving the problem]

[0005] 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 for converting the first radio wave into a first power and outputting the first radio wave, an output unit for using the first power to output a first signal for causing a power transmitting device to output a second radio wave, and a second circuit for converting the second radio wave from the power transmitting device into a second power and outputting the second radio wave.

[0006] 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 power and outputting the first power, a second output step of using the first power to output a first signal for causing a power transmission device to output a second radio wave, and a third output step of converting the second radio wave from the power transmission device into a second power and outputting the second power. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram for explaining an overview of a power transmission system using a power receiving device according to an embodiment. [Figure 2] 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. [Figure 3] FIG. 3 is a graph showing an example of the rectification efficiency characteristics of the first rectifier circuit and the second rectifier circuit shown in FIG. [Figure 4] FIG. 4 is a diagram showing a modified example of the rectifier circuit of the power receiving device. [Figure 5] FIG. 5 is a diagram illustrating an example of the configuration of the power transmitting device illustrated in FIG. [Figure 6] FIG. 6 is a diagram illustrating another example of a rectifying element used in a power receiving device. [Figure 7] FIG. 7 is a diagram illustrating an example of the configuration of a power receiving device according to a modified example of the embodiment. [Figure 8] FIG. 8 is a diagram illustrating another configuration example of a power receiving device according to a modified example of the embodiment. [Figure 9] FIG. 9 is a diagram illustrating an example of the configuration of a power receiving device including three rectifier circuits. DETAILED DESCRIPTION OF THE INVENTION

[0008] Several embodiments for implementing a power receiving device, a control method, etc. according to the present application will be described in detail with reference to the drawings. Note that the following description does not limit the present invention. Furthermore, the components in the following description include those that can be easily imagined by a person 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 assigned the same reference numerals. Furthermore, duplicated descriptions may be omitted.

[0009] FIG. 1 is a diagram illustrating an overview of a power transmission system using a power receiving device according to an embodiment. The system 1 illustrated in FIG. 1 includes, for example, a wireless power transmission system capable of microwave transmission (space transmission) wireless power transmission. Wireless power transmission is a mechanism that allows power to be transmitted without using, for example, a cable or a plug. The microwave transmission system 1 uses radio waves (microwaves) for energy transmission, and therefore uses narrowband, unmodulated frequencies. The system 1 transmits power in, for example, multiple frequency bands. In Japan, the multiple frequency bands include, for example, the 920 MHz band, the 2.4 GHz band, and the 5.7 GHz band. In this embodiment, the system 1 can simultaneously improve power supply efficiency appropriate for the situation and ensure safety. The system 1 can be applied to, for example, space solar power generation. Note that the frequency band of the radio waves used in the wireless power transmission system according to the embodiment of the present disclosure is not limited to microwaves, and radio waves with a wide wavelength range from several meters to several pm may be used.

[0010] In the example shown in FIG. 1 , the system 1 includes a power transmitting device 10 and a power receiving device 20. The power transmitting device 10 is a device that transmits power wirelessly in the system 1. The power transmitting device 10 is a device that can transmit radio waves for power supply. For example, a WPT (Wireless Power Transmission) power transmitting device can be used as the power transmitting device 10. The power transmitting 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 supply beam can be arbitrarily set. For example, the power transmitting device 10 performs directivity control by multiplying each antenna element by a weighting coefficient, and transmits radio waves 2000 for power supply. The directivity control means, for example, controlling the relationship between the radiation direction and radiation intensity of the radio waves 2000. As a result, the power transmitting device 10 radiates the radio waves 2000 in a radiation pattern with radiation directivity. The radio wave 2000 emitted by the power transmitting device 10 includes a main lobe 2100 that indicates a beam of a main component with strong electromagnetic intensity, and a side lobe 2200 that indicates a beam other than the main lobe 2100. The side lobe 2200 indicates a beam that is directed in a different direction from the main lobe 2100 and has weaker electromagnetic intensity than the main lobe 2100.

[0011] [Configuration of power receiving device] The power receiving device 20 is a power-supplied device in the system 1 that receives power-supply radio waves to obtain power. The power receiving device 20 outputs the power received from the power transmitting device 10 to a load 26. The load 26 includes, for example, mechanical equipment, IoT (Internet of Things) sensors, electronic devices, lighting equipment, etc. In this embodiment, the power receiving device 20 is configured to not require a power source such as a battery.

[0012] A WPT power receiving device can be used as the power receiving device 20. The power receiving device 20 includes a first antenna 21, a first rectifier circuit 22, a second rectifier circuit 23, an output unit 24, a second antenna 25, and a load 26.

[0013] The first antenna 21 is electrically connected to the first rectifier circuit 22 and the 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. The first antenna 21 may be, for example, a patch antenna, a dipole antenna, a parabolic antenna, or the like. The first antenna 21 outputs a signal of the received radio waves to the first rectifier circuit 22 and the second rectifier circuit 23.

[0014] The first rectifier circuit 22 is electrically connected to the output unit 24. The first rectifier circuit 22 efficiently converts a first high-frequency signal of a first electromagnetic intensity, among the radio waves received by the first antenna 21, into direct current. The first high-frequency signal includes, for example, a high-frequency signal that serves as input power to the rectifier circuit and is necessary for the power receiving device 20 to output the specified signal 3000. The first high-frequency signal includes, for example, a signal that indicates the beam of a side lobe 2200 of the radio wave 2000. An example configuration of the first rectifier circuit 22 will be described later. The first rectifier circuit 22 outputs a direct current (first power) obtained by converting the first high-frequency signal to the output unit 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 a first radio wave.

[0015] The second rectifier circuit 23 is electrically connected to the load 26. The second rectifier circuit 23 converts, into DC, a second high-frequency signal of a second electromagnetic intensity, which is stronger than the first electromagnetic intensity, among the radio waves received by the first antenna 21. The second high-frequency signal includes, for example, a high-frequency signal that serves as input power to the rectifier circuit and is required to operate the load 26 of the power receiving device 20. The second high-frequency signal includes, for example, a signal that indicates the beam of the main lobe 2100 of the radio waves 2000. The second rectifier circuit 23 does not convert the first high-frequency signal of the first electromagnetic intensity described above. An example configuration of the second rectifier circuit 23 will be described later. The second rectifier circuit 23 converts the second high-frequency signal and outputs the DC current (second power) 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 may have the highest conversion efficiency when converting a first high-frequency signal of a first electromagnetic intensity into DC, and the second rectifier circuit 23 may have the highest conversion efficiency when converting a second high-frequency signal of a second electromagnetic intensity into DC. 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 a second radio wave.

[0016] The output unit 24 is electrically connected to the second antenna 25. The output unit 24 outputs (transmits) the regulation signal 3000 using the power output from the first rectifier circuit 22. The regulation signal 3000 includes, for example, a beacon signal, a pilot signal, etc. The output unit 24 generates the regulation signal 3000 for supply path estimation using, for example, a transmission circuit, etc., and outputs the regulation signal 3000 to the second antenna 25.

[0017] The second antenna 25 is an antenna capable of emitting radio waves including the signal output by the output unit 24. The second antenna 25 may be, for example, a patch antenna, a dipole antenna, a parabolic antenna, or the like. The second antenna 25 emits radio waves including the signal output by the output unit 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 realized by a single antenna.

[0018] Examples of load 26 include, but are not limited to, a battery, a storage battery, a capacitor, a CPU (Central Processing Unit), sensors such as a thermometer, a hygrometer, a vibration meter, imaging equipment such as a camera, an antenna, a light, a drone, and machine tools. Load 26 may be any suitable device.

[0019] An example of the functional configuration of the power receiving device 20 according to this embodiment has been described above. Note that the above configuration described using Fig. 1 is merely an example, and the functional configuration of the power receiving device 20 according to this embodiment is not limited to this example. The functional configuration of the power receiving device 20 according to this embodiment can be flexibly modified according to specifications and operation.

[0020] Next, an example of the operation of the system 1 will be described. In scene C1, the power transmitting device 10 performs directivity control by multiplying each antenna by a weighting coefficient, and emits radio waves 2000 for power supply. Directivity control means, for example, controlling the relationship between the radiation direction and radiation intensity of the radio waves 2000. As a result, the power transmitting device 10 emits the radio waves 2000 in a radiation pattern having radiation directivity. In the example shown in FIG. 1 , the power transmitting device 10 emits the radio waves 2000 in which a main lobe 2100 is directed in a direction different from the power receiving device 20 and a side lobe 2200 is directed in a direction near the power receiving device 20. The beam of the side lobe 2200 of the radio waves 2000 emitted by the power transmitting device 10 is directed toward the power receiving device 20.

[0021] The power receiving device 20 receives the beam of side lobes 2200 of radio waves 2000 radiated by the power transmitting device 10 at the first antenna 21 as a first high-frequency signal of a first electromagnetic intensity. The power receiving device 20 converts the received first high-frequency signal into a direct current at the first rectifier circuit 22 and outputs the converted signal to the output unit 24 (first output step). The power receiving device 20 radiates radio waves including the regulated signal 3000 from the second antenna 25 by causing the output unit 24 to use the direct current to output a regulated signal 3000 (first signal) for causing the power transmitting device 10 to output a second radio wave (second output step). The beam of radio waves radiated 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 received first high-frequency signal into a direct current at the second rectifier circuit 23 because the intensity of the first high-frequency signal is weaker than the second electromagnetic intensity.

[0022] Upon receiving the regulation signal 3000, the power transmitting device 10 estimates the position of the power receiving device 20 based on the regulation signal 3000. For example, the power transmitting device 10 estimates a reception response vector by comparing the received regulation signal 3000 with a known reference signal. The power transmitting device 10 calculates a weighting coefficient for transmission for the estimated position of the power receiving device 20 (reception response vector).

[0023] In scene C2, the power transmitting device 10 performs directivity control by multiplying multiple antenna elements by weighting coefficients, and radiates radio waves 2000 of a transmission signal for power supply toward the power receiving device 20. The power transmitting device 10 radiates the radio waves 2000 of the transmission signal, with a main lobe 2100 directed toward the power receiving device 20 and side lobes 2200 directed in a direction different from that of the power receiving device 20.

[0024] 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 at the first antenna 21 as a second high-frequency signal of a second electromagnetic intensity. The power receiving device 20 converts the received second high-frequency signal into a direct current at the second rectifier circuit 23 and outputs (supplies) the direct current to the load 26 (third output step). As a result, the power receiving device 20 operates the load 26 using the direct current output from the second rectifier circuit 23. Note that most of the received second high-frequency signal appears as a direct current output from the second rectifier circuit 23 in the power receiving device 20.

[0025] As described above, the power receiving device 20 converts the first high-frequency signal of the first electromagnetic intensity into DC using the first rectifier circuit 22, and converts the second high-frequency signal of an intensity stronger than the first electromagnetic intensity into DC using the second rectifier circuit 23. The power receiving device 20 radiates the regulated signal 3000 from the second antenna 25 using the power output from the first rectifier circuit. This allows the power receiving device 20 to radiate the regulated signal 3000 from 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 cause the power transmitting device 10 to determine the position of the power receiving device 20 without having a power source or the like for operating the output unit 24.

[0026] The power receiving device 20 can convert the second high-frequency signal, which has a stronger intensity than the first electromagnetic intensity, into power that drives the load 26 using the second rectifier circuit 23. This allows the power receiving device 20 to receive a high-power high-frequency signal from the power transmitting device 10, and to 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, whose position the power receiving device 20 has been determined, without having a power source.

[0027] 1 illustrates an example of a system 1 in which the power transmission beam of the power transmission device 10 is not properly irradiated onto the power receiving device 20, or the power transmission beam is irradiated over a wide area, resulting in a low power received by the first antenna 21 of the power receiving device 20. In this case, most of the received power appears as a DC output from the first rectifier circuit 22 of the power receiving device 20, driving the output unit 24 to transmit a specified signal 3000 from the second antenna 25. When the specified signal 3000 is received by the power transmission device 10, the power transmission device 10 irradiates a radio wave 2000 including a beam with a narrowed irradiation range toward the power receiving device 20. When the first antenna 21 of the power receiving device 20 receives this beam, most of the received power appears as a DC output from the second rectifier circuit 23, and wireless power is supplied to the load 26. As a result, the system 1 can determine the location of the power receiving device 20 that does not have a power source simply by having the power transmitting device 10 output a power supply transmission signal, so the power transmitting device 10 does not need to manage the location of the power receiving device 20 in advance, allowing for flexibility in the placement of the devices.

[0028] 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 rectifier circuits. A single-shunt rectifier circuit is composed of one diode and a λ / 4 line, and has relatively good efficiency characteristics at high frequencies.

[0029] The first rectifier circuit 22 has a diode 221, a λ / 4 line 222, and a capacitor 223. The anode of the diode 221 is grounded, and the cathode is electrically connected to the first antenna 21. The λ / 4 line 222 is composed of a line with 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 unit 24. The other end of the capacitor 223 is grounded.

[0030] The second rectifier circuit 23 has a diode 231, a λ / 4 line 232, and a capacitor 233. The anode of the diode 231 is grounded, and the cathode is electrically connected to the first antenna 21. The λ / 4 line 232 is composed of a line with 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.

[0031] In the following description, the microwave voltage 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 the supply voltage. The DC voltage output from the first rectifier circuit 22 and the second rectifier circuit 23 will be referred to as the output voltage.

[0032] In known rectifier circuits, as the input power increases, the input voltage increases relative to the diode's forward voltage Vf, so the conversion efficiency increases up to a certain point, but as the breakdown voltage Vb is approached, reverse current flows and the conversion efficiency decreases. Therefore, the position of the efficiency peak point of a rectifier circuit varies depending on the diode characteristics (Vf and Vb).

[0033] The power receiving device 20 according to this embodiment utilizes the difference in characteristics between two types of rectifying elements with different characteristics, namely, the diode 221 and the diode 231. The power receiving device 20 is configured with two rectifying circuits: a first rectifying circuit 22 that efficiently converts a weak first high-frequency signal into DC, and a second rectifying circuit 23 that efficiently converts a second high-frequency signal that is stronger than the first high-frequency signal into DC.

[0034] 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 represents input power [dBm], and the vertical axis represents the ratio of rectified DC power to input power, i.e., rectification efficiency [%].

[0035] The efficiency with which a rectifier circuit converts a high-frequency signal into DC power and its input / output characteristics are determined by the characteristics of the diode, which is the rectifier element. The example shown in Figure 3 shows the difference in rectification efficiency characteristics between two different types of diodes, 221 and 231.

[0036] As shown in graph G2, the second rectifier circuit 23 equipped with diode 231 has almost zero output when the input power is 0 dBm or less. As shown in graph G1, the first rectifier circuit 22 equipped with diode 221 can obtain output even when the input power is 0 dBm or less. In other words, the weak first high-frequency signal includes a high-frequency signal with an input power of 0 dBm or less. The efficiency characteristics of the first rectifier circuit 22 and the second rectifier circuit 23 reverse at an input power of 17 dBm, and the efficiency of the second rectifier circuit 23 becomes good in the high-power range where the input power exceeds 20 dBm.

[0037] Therefore, when receiving weak power of about 0 dBm, the power receiving device 20 according to this embodiment can use the output of the first rectifier circuit 22 to drive the output unit 24 and transmit the regulated signal 3000. Thereafter, when the power receiving device 200 receives a power supply beam (second high-frequency signal) of 17 dBm or more transmitted by the power transmitting device 10 in response to receiving the regulated signal 3000, the second rectifier circuit 23 can supply a large output to the load 26.

[0038] [Modification of rectifier circuit] The above-described power receiving device 20 has been described as using single-shunt rectifier circuits as the first rectifier circuit 22 and the second rectifier circuit 23, but is not limited to this. For example, the power receiving device 20 may use rectifier circuits of different types as the first rectifier circuit 22 and the second rectifier circuit 23. For example, the power receiving device 20 may use a rectifier circuit known as a double-shunt rectifier circuit. A double-shunt rectifier circuit functions as a voltage doubler rectifier circuit and is therefore used in applications requiring a relatively high output voltage.

[0039] Fig. 4 is a diagram showing a modified example 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 unit 24, a second antenna 25, and a load 26. That is, in the power receiving device 20, the first rectifier circuit 22-1, which is a low-power rectifier circuit, uses a double-shunt system to obtain the voltage required by the output unit 24 that outputs the specified signal 3000 with as little input power as possible, and the second rectifier circuit 23, which is a high-power rectifier circuit, uses the above-mentioned single-shunt system to obtain high efficiency.

[0040] The first rectifier circuit 22-1 has one end electrically connected to the first antenna 21 and the other end electrically connected to the output unit 24. The first rectifier circuit 22-1 efficiently converts a first high-frequency signal of a first electromagnetic intensity, among the radio waves received by the first antenna 21, into direct current. The first rectifier circuit 22-1 has a diode 221, a diode 224, and a capacitor 223. The anode of the diode 221 is grounded, and the cathode is electrically connected to the first antenna 21. The anode of the diode 224 is electrically connected to the first antenna 21 and the cathode of the diode 221, and the cathode is connected to one end of the capacitor 223 and the output unit 24. The other end of the capacitor 223 is grounded.

[0041] 4, the power receiving device 20 utilizes the difference in characteristics between two different types of rectifier circuits, a first rectifier circuit 22-1 and a second rectifier circuit 23. The power receiving device 20 includes two rectifier circuits: a first rectifier circuit 22-1 that efficiently converts a weak first high-frequency signal into DC, and a second rectifier circuit 23 that efficiently converts a second high-frequency signal that is stronger than the first high-frequency signal into DC.

[0042] The power receiving device 20 converts a first high-frequency signal of a first electromagnetic intensity into DC using a first rectifier circuit 22-1, and converts a second high-frequency signal of an intensity stronger than the first electromagnetic intensity into DC using a second rectifier circuit 23. The power receiving device 20 radiates a regulated signal 3000 from the second antenna 25 using the power output from the first rectifier circuit 22-1. As a result, even if the intensity of the radio waves 2000 received by the first antenna 21 is weak, the power receiving device 20 can transmit the regulated signal 3000 using the power obtained by converting the first high-frequency signal. As a result, the power receiving device 20 can allow the power transmitting device 10 to determine the location of the power receiving device 20 without having a power source.

[0043] [Configuration of power transmission equipment] Fig. 5 is a diagram illustrating an example of the configuration of the power transmitting device 10 shown in Fig. 1. As shown in Fig. 5, the power transmitting device 10 includes an antenna 11, a transmission signal generating unit 12, a transmitting unit 13, a receiving unit 14, an estimating unit 15, a storage unit 16, and a control unit 17. The control unit 17 is electrically connected to the transmission signal generating unit 12, the transmitting unit 13, the receiving unit 14, the estimating unit 15, the storage unit 16, and the like. In this embodiment, for the sake of simplicity, the power transmitting device 10 will be described with respect to a case where the antenna 11 includes four antenna elements 11A, but the number of antenna elements 11A is not limited to this.

[0044] The antenna 11 is configured to enable directivity control (beamforming). The antenna 11 is an antenna array equipped with a plurality of antenna elements 11A. For example, the antenna 11 is configured such that 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 weakened by canceling each other out in another direction. The antenna 11 emits radio waves 2000 including a transmission signal and receives radio waves including a signal from the power receiving device 20. The antenna 11 supplies the received signal to the receiving unit 14.

[0045] The transmission signal generation unit 12 generates a transmission signal for power supply by converting a current to be transmitted to the power receiving device 20 into a radio wave. The transmission signal is a signal for transmitting a radio wave capable of supplying power. The transmission signal generation unit 12 generates the transmission signal by converting a current from a power source (not shown) into a radio wave of a transmission frequency. The power source includes, for example, a commercial power source, a DC power source, a battery, etc. The transmission signal generation unit 12 supplies the generated transmission signal to the transmission unit 13.

[0046] The transmitter 13 is electrically connected to the multiple antenna elements 11A of the antenna 11. The transmitter 13 causes the antenna 11 to emit radio waves including a transmission signal for power supply. The transmitter 13 applies weights corresponding to beams that can be formed by the multiple antenna elements 11A, thereby causing the multiple antenna elements 11A to emit the radio waves in specific directions. The transmitter 13 applies weights instructed by the controller 17 to the multiple antenna elements 11A.

[0047] The receiving unit 14 is electrically connected to the multiple antenna elements 11A of the antenna 11, the estimation unit 15, etc. 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 specified signal 3000, etc. The receiving unit 14 supplies the extracted received signal to the estimation unit 15, the control unit 17, etc.

[0048] The estimation unit 15 estimates the radio wave propagation environment from the known specified signal 3000 received from the power receiving device 20. The radio wave propagation environment includes, for example, the space through which radio waves propagate 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 state of radio wave propagation includes, for example, a state in which it is possible to distinguish between an environment where direct waves are dominant and a multipath-rich environment where reflected waves occur. The estimation unit 15 estimates a reception response vector (terminal arrival direction) from the received signal. For example, the estimation unit 15 estimates the reception response vector by comparing the known specified 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, and reception response vector of the specified signal 3000, a reference propagation model, a machine learning program, etc., in order to grasp the state of radio wave propagation in space. For example, when the loss of the received specified signal 3000 is smaller than the determination threshold, the estimation unit 15 estimates that the radio wave propagation environment is a direct wave-dominated environment. For example, when the loss of the received specified signal 3000 is equal to or greater than the determination threshold, the estimation unit 15 estimates that the radio wave propagation environment is a multipath-rich environment. The estimation unit 15 supplies the estimation result based on the specified signal 3000 to the control unit 17.

[0049] 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 or 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 reader. The storage unit 16 may include a storage device used as a temporary storage area, such as RAM.

[0050] The storage unit 16 can store weight data 161 and the like. The weight data 161 has, for example, data indicating a plurality of weights (weighting coefficients) for adjusting the amplitude and phase of signals radiated from a plurality of antenna elements 11A of the antenna 11 for each of a plurality of directivity patterns. The weight data 161 has, for example, data indicating a combination of a plurality of antenna elements 11A corresponding to a directivity pattern.

[0051] The control unit 17 includes one or more arithmetic units. Examples of the arithmetic units include, but are not limited to, a central processing unit (CPU), a system-on-a-chip (SoC), a micro control unit (MCU), a field-programmable gate array (FPGA), and a coprocessor. The control unit 17 executes a program in the arithmetic unit to realize processing related to various operations of the power transmitting device 10.

[0052] 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 a reception response vector by comparing the received regulation signal 3000 with a known reference signal. The control unit 17 refers to the weight data 161 and calculates a weighting coefficient for transmission for 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 the weighting coefficient, and causes the radio waves 2000 of the transmission signal for power supply to be emitted toward the power receiving device 20. For example, the control unit 17 performs directivity control by multiplying the plurality of antenna elements 11A by the weighting coefficient, and can cause the radio waves 2000 including a first high-frequency signal of a first electromagnetic intensity to be emitted over a wide range. The control unit 17 can cause the radio waves to be emitted over a wide range periodically or irregularly.

[0053] An example of the functional configuration of the power transmitting device 10 according to this embodiment has been described above. Note that the configuration described above using Fig. 5 is merely an example, and the functional configuration of the power transmitting device 10 according to this embodiment is not limited to this example. The functional configuration of the power transmitting device 10 according to this embodiment can be flexibly modified according to specifications and operation.

[0054] The power transmitting device 10 emits radio waves 2000 including a first high-frequency signal of a first electromagnetic intensity over a wide range from the antenna 11 while the direction of the power receiving device 20 is unknown. As a result, when the power receiving device 20 receives the radio waves 2000 at the first antenna 21, the power receiving device 20 transmits a regulated signal 3000 from the second antenna 25 using the DC output of the first rectifier circuit 22. The power transmitting device 10 then estimates the position of the power receiving device 20 based on the regulated signal 3000 received at the antenna 11, and emits radio waves 2000 including a transmission signal for power feeding toward the power receiving device 20. As a result, when the power receiving device 20 receives the radio waves 2000 at the first antenna 21, the load 26 operates using the DC output of the second rectifier circuit 23.

[0055] As described above, the system 1 can grasp the presence and direction of the power receiving device 20 by having the power transmitting device 10 emit the radio waves 2000 over a wide range. As a result, even if the power transmitting device 10 does not know the position of the power receiving device 20 that does not have a power source in advance, the system 1 can perform efficient wireless charging because the power transmitting device 10 can irradiate a power feeding beam in the direction of the power receiving device 20.

[0056] [Modification of power receiving device] Fig. 6 is a diagram for explaining another example of a rectifying element used in the power receiving device 20. In Fig. 6, the horizontal axis represents input power [dBm], and the vertical axis represents the ratio of rectified DC power to input power, i.e., rectification efficiency [%]. Fig. 6 is a diagram in which graph G3 is added to graphs G1 and G2 of Fig. 3 described above.

[0057] As shown in FIG. 6, the power receiving device 20 can use a diode 291 having characteristics intermediate between the diodes 221 and 231 described above. For example, the diodes 221, 231, and 291 differ in the input power at which they rise and the input power at which their rectification efficiency (output power) peaks. As shown in graph G3, the diode 291, like the diode 221, can obtain output even when the input power is 0 dBm or less. The efficiency characteristics of the diodes 221 and 291 are reversed at an input power of 12 dBm, and the efficiency of the second rectifier circuit 23 is good in the high-power range exceeding 20 dBm. Therefore, the power receiving device 20 can configure an optimal power transmission system by selecting a combination of the diodes 221, 231, and 291 based on the power required by the beacon transmission circuit of the output unit 24 to be used and the power to be supplied to the load 26. For example, by replacing the diode 231 of the second rectifier circuit 23 with a diode 291, the power receiving device 20 can make the second rectifier circuit 23 output even when the input power is 0 dBm or less.

[0058] The above-described power receiving device 20 may be configured to combine outputs from a plurality of rectifier circuits and supply the combined power to a single load 26. Fig. 7 is a diagram showing an example configuration of the power receiving device 20 according to a modified example of the embodiment. As shown in Fig. 7, the power receiving device 20 may be configured such that the first rectifier circuit 22 is electrically connected to the output unit 24 and the load 26. This allows the power receiving device 20 to combine outputs from the first rectifier circuit 22 and the second rectifier circuit 23 and output the combined power to the load 26, thereby enabling efficient power transmission regardless of the magnitude of the input power of the high-frequency signal received by the first antenna 21.

[0059] The power receiving device 20 described above has been described as switching between the first rectifier circuit 22 and the second rectifier circuit 23 that are operated in accordance with the characteristics of the rectifier elements, but is not limited to this. Fig. 8 is a diagram showing another configuration example of the power receiving device 20 according to a modified example of the embodiment.

[0060] 8, the power receiving device 20 can be configured to include a first antenna 21, a first rectifier circuit 22, a second rectifier circuit 23, an output unit 24, a second antenna 25, a load 26, a monitoring unit 27, and a switch 28. That is, the power receiving device 20 can be configured to include the monitoring unit 27 and the switch 28.

[0061] 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 into which the second rectifier circuit 23 converted the signal. The monitoring unit 27 is electrically connected to the switch 28. When the voltage converted by the second rectifier circuit 23 exceeds a certain value, the monitoring unit 27 outputs a switching signal to the switch 28. When the voltage converted by the second rectifier circuit 23 is equal to or lower than the certain value, the monitoring unit 27 does not output the switching signal to the switch 28.

[0062] The switch 28 is configured to be able to switch between the first rectifier circuit 22 and the second rectifier circuit 23, which convert the high-frequency signal. The switch 28 is incorporated in the branch line 20A that branches from the first antenna 21 to the first rectifier circuit 22, and is an analog switch that is able to switch between inputting and blocking 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 blocks the input of a signal to the first rectifier circuit 22 when the output of the second rectifier circuit 23 exceeds the certain value. In this embodiment, the switch 28 blocks the input of a signal to the first rectifier circuit 22 in response to a switching signal from the monitoring unit 27.

[0063] In the power receiving device 20, a first rectifier circuit 22 for low power and a second rectifier circuit 23 for high power are connected in parallel, and the difference in received power is converted into a voltage by a monitoring unit 27, and the switch 28 can be switched based on that voltage. In this way, the power receiving device 20 can reduce the influence of the rectifier circuits by switching between two or more rectifier circuits with different rectification characteristics, and further improve rectification efficiency. Note that when the monitored voltage is low power, the diode 231 of the second rectifier circuit 23 is cut off, so there is no need to shut off the second rectifier circuit 23.

[0064] Fig. 9 is a diagram showing an example of the configuration 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 unit 24, a second antenna 25, a load 26, and a third rectifier circuit 29. The power receiving device 20-1 is configured such that the first rectifier circuit 22, the second rectifier circuit 23, and the third rectifier circuit 29, which have three different rectification characteristics, are arranged in parallel.

[0065] The first antenna 21 is electrically connected to the first rectifier circuit 22, the second rectifier circuit 23, and the third rectifier circuit 29. The first rectifier circuit 22 includes the above-mentioned diode 221. The second rectifier circuit 23 includes the above-mentioned diode 231. The third rectifier circuit 29 includes the above-mentioned diode 291 (see FIG. 6).

[0066] The third rectifier circuit 29 is electrically connected to the load 26. The third rectifier circuit 29 converts, into direct current, 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. The third rectifier circuit 29 outputs the direct 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.

[0067] The power receiving device 20-1 can achieve high transmission efficiency over a wide range of input power by switching between three rectifier circuits with different rectification characteristics according to the input power or by combining the outputs.

[0068] Characteristic embodiments have been described to fully and clearly disclose the technology claimed in the appended claims. However, the appended claims should not be limited to the above-described embodiments, but should be construed to embody all modifications and alternative configurations that may be conceived by those skilled in the art within the scope of the basic concepts set forth herein. Those skilled in the art can make various modifications and alterations to the content of the present disclosure based on the present disclosure. Therefore, these modifications and alterations are within the scope of the present disclosure. For example, in each embodiment, each functional unit, each means, each step, etc. may be added to other embodiments without logical contradiction, or may be replaced with each functional unit, each means, each step, etc. of other embodiments. Furthermore, in each embodiment, multiple functional units, each means, each step, etc. may be combined or divided into one. Furthermore, each embodiment of the present disclosure described above is not limited to faithful implementation of each described embodiment, and each feature may be combined or partially omitted as appropriate. The method of the present disclosure may be implemented by a device equipped with a CPU and memory, in which the CPU executes a program stored in the memory. [Explanation of symbols]

[0069] 1 System 10 Power transmission equipment 11 Antenna 12 Transmission signal generator 13 Transmitter 14 Receiving unit 15 Estimation part 16 Memory section 17 Control Unit 20,20-1 Power receiving device 21 First Antenna 22 1st rectifier circuit 23 Second rectifier circuit 24 Output section 25 Second Antenna 26 Load 27 Monitoring Department 28 Switch 29 Third rectifier circuit 221 Diode 222 λ / 4 line 223 Capacitor 231 Diode 232 λ / 4 track 233 Capacitor 2000 Radio Waves 2100 Main Lobe 2200 Sidelobe 3000 regulation signal

Claims

1. an antenna for receiving the first radio wave and the second radio wave; a first circuit that converts the first radio wave into a first power and outputs the first power; an output unit that outputs a first signal to cause a power transmitting device to output a second radio wave using the first power; a second circuit that converts the second radio wave from the power transmitting device into second power and outputs the second power; Equipped with a power receiving device that combines outputs from the first circuit and the second circuit to output power capable of driving a load;

2. In the power receiving device according to claim 1, 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 converted voltage; A power receiving device comprising:

3. 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. Power receiving device.

4. 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. Power receiving device.

5. 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. Power receiving device.

6. The power receiving device according to claim 1 , A load is driven by the second power output from the second circuit. Power receiving device.

7. a first output step of converting the first radio wave received from an antenna for receiving the first radio wave and the second radio wave into a first power and outputting the first power; a second output step of outputting a first signal to cause a power transmitting device to output a second radio wave using the first power; a third output step of converting the second radio wave from the power transmitting device into second power and outputting the second power; Including, A control method for a power receiving device that combines the outputs from the first output step and the second output step to output power capable of driving a load.

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