JP2020010485A - Wireless power supply device and wireless power supply system - Google Patents

Abstract

To provide a technique capable of regulating a radio wave transmitted from each antenna element of an array antenna quickly so as to be an efficient power supply.SOLUTION: A wireless power supply device according to the present invention is provided with: power supply signal generation means for generating a power supply signal; propagation coefficient calculation means for calculating each propagation coefficient between a plurality of antenna elements and an antenna of a power supply target device; weight calculation means for calculating a weight for regulating the phase and the amplitude of the power supply signal generated by the power supply signal generation means on the basis of each propagation coefficient, for every one of the plurality of antenna elements; and power supply signal distribution means for regulating the phase and the amplitude of the power supply signal generated by the power supply signal generation means on the basis of the weight calculated by the weight calculation means for every one of the plurality of antenna elements, and distributing the power supply signal after the regulation to the plurality of antenna elements. The plurality of antenna elements forming an array antenna convert the power supply signal to a power supply radio wave and transmit the power supply radio wave to the power supply target device.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wireless power supply device and a wireless power supply system.

  Wireless data communication between an RFID tag and an RFID reader and wireless power supply from the RFID reader to the RFID tag are performed using an RFID (Radio Frequency IDentifier) technology. For wireless data communication and wireless power supply, for example, an array antenna in which a plurality of antenna elements are regularly arranged is provided in an RFID reader.

  When wireless power is supplied by transmitting radio waves from the array antenna, power supply radio waves transmitted from a plurality of antenna elements forming the array antenna may interfere with each other, and supply power received by the power supply target device may decrease. Therefore, a technique for adjusting a radio wave transmitted from each antenna element has been disclosed (for example, Patent Documents 1-2).

JP 2015-164318 A Japanese Patent Publication No. 2008-204061

  In Patent Document 1, the phase and amplitude of a radio wave transmitted from each antenna element of an array antenna are searched according to a predetermined search algorithm. However, execution of a search by a search algorithm requires time. Therefore, the throughput is reduced and it takes time to supply power. Also, for example, when the propagation environment between the array antenna and the antenna of the device to be fed changes, the method using the search algorithm adjusts the radio wave transmitted from each antenna element in order to quickly respond to the change in the propagation environment. However, it is difficult to maintain communication reliability.

  In Patent Document 2, a search by a search algorithm is not performed, a signal from a power supply target device is received, a path difference between an antenna of the power supply target device and each antenna element is detected, and a feed signal of a power supply signal is detected in accordance with the path difference. The phase is being adjusted. However, the amplitude of the power supply signal is not controlled. That is, when power is supplied using the technique disclosed in Patent Document 2, the power supplied to the power supply target device is not maximized, and there is a possibility that the power may be supplied inefficiently.

  That is, the present inventor has found that in the related art, radio waves transmitted from each antenna element of the array antenna cannot be adjusted quickly and efficiently so that power is supplied.

  In one aspect, the present invention has been made in view of such circumstances, and an object of the present invention is to adjust radio waves transmitted from each antenna element of an array antenna so that power can be supplied quickly and efficiently. It is to provide technology that can do it.

  The present invention employs the following configuration in order to solve the above-described problems.

That is, a wireless power supply device according to one aspect of the present invention is a wireless power supply device including an array antenna formed from a plurality of antenna elements, wherein a power supply signal generation unit configured to generate a power supply signal; A propagation coefficient calculating unit that calculates respective propagation coefficients between the antenna of the target device, and the power supply generated by the power supply signal generating unit based on the respective propagation coefficients calculated by the propagation coefficient calculating unit. Weight calculating means for calculating a weight for adjusting a phase and an amplitude of a signal for each of the plurality of antenna elements; and the power supply generated by the power supply signal generating means based on the weight calculated by the weight calculating means. The phase and amplitude of the signal are adjusted for each of the plurality of antenna elements, and the feed signal adjusted for each of the plurality of antenna elements is supplied to the plurality of antenna elements. And a feed signal distributing means for distributing the feed power to the antenna device, wherein the plurality of antenna elements forming the array antenna convert the distributed feed signal into a feed radio wave and transmit the feed radio wave to the device to be fed. Wireless power supply device.

  According to this configuration, the weight is calculated based on the propagation coefficient between each antenna element of the wireless power supply apparatus and the antenna of the device to be fed, and the phase of the feed signal is adjusted based on the weight, whereby the phase is adjusted. The supplied power signal is distributed to each antenna element. The adjustment of the phase is not performed uniformly, but is performed for each of the plurality of antenna elements. Then, in each antenna element, the power supply signal is converted into a power supply radio wave, and the power supply radio wave is transmitted to the power supply target device. That is, the configuration adjusts the phase of the power supply signal according to the propagation environment between each antenna element and the antenna of the power supply target device, so that each power supply radio wave received by the power supply target device from each antenna element is in-phase. can do. Therefore, this configuration can improve power supply efficiency to the power supply target device.

  Further, according to the configuration, the amplitude of the power supply signal is also adjusted based on the weight. That is, the power supplied from each antenna element to the power supply target device is adjusted. That is, this configuration can maximize the power supplied to the power supply target device according to the propagation environment between each antenna element and the antenna of the power supply target device.

  Further, according to the configuration, the processing for adjusting the phase and the amplitude of the power supply signal, such as the calculation of the propagation coefficient and the calculation of the weight, is executed on the wireless power supply apparatus side, not on the power supply target apparatus side. Here, unlike the configuration, when a process for adjusting the phase and amplitude of the power supply signal such as calculation of the propagation coefficient and calculation of the weight is performed on the power supply target device side, the result calculated on the power supply target device side is used. It is necessary to transmit to the wireless power supply device side. When such transmission is performed, it is preferable to increase the SNR (Signal Noise Ratio) of the transmission radio wave. Therefore, it is conceivable that the power supply target device performs signal processing such as amplification of a transmission signal and removal of noise included in the transmission signal. In addition, these signal processes require power. On the other hand, according to the configuration, such signal processing becomes unnecessary. Therefore, power consumption on the power supply target device side can be reduced. Therefore, such a configuration is an effective configuration when the power supply target device is a device that does not include a battery.

  In the wireless power feeding apparatus according to the one aspect, a request signal for requesting a response to the power supply target device is transmitted to the power supply target device via the plurality of antenna elements forming the array antenna, and the request signal is transmitted to the power supply target device. A response signal from the power supply target device is received via the plurality of antenna elements, and the propagation coefficient calculating unit determines whether the plurality of antenna elements and the antenna of the power supply target device are based on the received response signal. May be calculated.

  According to this configuration, transmission and reception of radio waves between each antenna element forming the array antenna and the antenna of the power supply target device is performed once, and a propagation coefficient is calculated based on information obtained by transmission and reception of the radio waves. Can be. Therefore, the propagation coefficient is quickly calculated without any trouble or time. Therefore, a decrease in throughput is suppressed, and the power supply time is reduced.

  In the wireless power supply device according to the one aspect, transmission of the request signal to the power supply target device and reception of the response signal from the power supply target device to the transmitted request signal include power supply to the power supply target device. May be performed each time.

  According to this configuration, even when the propagation coefficient between the array antenna and the antenna of the device to be fed changes, the feed radio wave transmitted from each antenna element quickly changes according to the change in the propagation coefficient. Adjusted. That is, the configuration can promptly respond to a change in the propagation environment and suppress a decrease in communication reliability.

  In the wireless power feeding apparatus according to the one aspect, the wireless power feeding apparatus further includes a storage unit that sequentially stores the weights calculated by the weight calculation unit, wherein the weight calculation unit is configured to store the weight when the response signal is not received. A weight may be predicted based on the stored weights for the predetermined number of times, and the weight calculated based on the propagation coefficient may be substituted by the predicted weight.

  According to this configuration, even when the propagation coefficient cannot be calculated because the response signal cannot be received, the weight can be calculated based on the weight calculated in the past and stored by the storage unit, and the weight can be predicted. Then, by substituting the weight calculated based on the propagation coefficient with the predicted weight, the phase and the amplitude of the power supply signal are adjusted even when the propagation coefficient cannot be calculated.

  In the wireless power supply device according to the one aspect, the weight is predicted by multiplying a predetermined number of weights stored by the storage unit by a weight prediction coefficient corresponding to each of the predetermined number of weights. The weight calculation means, when receiving the response signal earlier than when not receiving the response signal, performs the prediction of the weight in addition to calculating the weight based on the propagation coefficient, the calculated The weight prediction coefficient may be updated so that the difference between the weight based on the propagation coefficient and the predicted weight is minimized.

  According to this configuration, the weight prediction coefficient is optimized so that the difference between the weight calculated based on the propagation coefficient and the predicted weight is minimized. Therefore, even when the weight cannot be calculated based on the propagation coefficient, the weight can be predicted with high accuracy using the weight prediction coefficient. The weight prediction coefficient is updated even when the weight is calculated based on the propagation coefficient. That is, even when the propagation environment changes, the accuracy of weight prediction is maintained.

  In the wireless power supply device according to the above aspect, the power supply signal generation unit may generate a power supply signal to be transmitted to a plurality of power supply target devices.

  According to this configuration, power can be supplied to a plurality of power supply target devices at once. That is, the wireless power supply device is a highly convenient device.

  In addition, a wireless power supply system according to one aspect of the present invention includes an antenna, and a modulated signal generation module that, when receiving a radio wave from a device outside the system via the antenna, generates a modulation signal obtained by modulating the received radio wave. And a wireless power supply apparatus according to the one aspect, further comprising: a demodulation unit configured to demodulate the modulation signal when the modulation signal is received from the power supply target apparatus. And may be provided.

According to this configuration, when the power supply target device receives the request signal from the wireless power supply device, the power supply target device can generate a modulated signal obtained by modulating the request signal, and transmit the modulated signal to the wireless power supply device. In other words, the power supply target device can transmit a signal to the wireless power supply device without using the oscillator. That is, according to the configuration, power for operating the oscillator in the power supply target device is not required, and power saving is realized. In addition, the power supply target device can transmit a signal to the wireless power supply device without having a power storage unit for storing power for operating the oscillator, thereby reducing the cost of parts.

  Further, according to this configuration, the propagation coefficient calculation means calculates the propagation coefficient based on the request signal transmitted to the power supply target device and the modulation signal received from the power supply target device, and the modulation signal is the request signal. If the signal is not a signal obtained by modulating the above frequency, there is no difference between the frequency of the request signal and the frequency of the modulated signal, so that the propagation coefficient can be calculated without considering the difference. That is, the propagation coefficient calculating means can easily calculate the propagation coefficient.

  In the wireless power supply system according to the one aspect, the power supply target device may further include a power storage unit.

  According to this configuration, the power supply target device can perform a process that requires predetermined power regardless of whether power is supplied from the wireless power supply device to the power supply target device. The processing requiring predetermined power is, for example, when the power supply target device includes an oscillator, the operation of the oscillator, the processing of signal amplification and noise removal, or the processing of communication with a wireless power supply apparatus.

  In the wireless power feeding system according to the one aspect, the antenna included in the power supply target device may be formed from a plurality of antenna elements.

  According to this configuration, the number of propagation paths (paths) of radio waves between the wireless power supply apparatus and the power supply target device increases, and radio waves propagated through a plurality of paths can be concentrated on the power supply target device. Therefore, power supply efficiency to the power supply target device is increased.

  ADVANTAGE OF THE INVENTION According to this invention, the technique which can adjust so that the electric wave transmitted from each antenna element of an array antenna can be supplied quickly and efficiently can be provided.

FIG. 1 schematically illustrates an example of the outline of the wireless power supply system. FIG. 2 schematically illustrates an example of a flowchart illustrating an outline of the operation of the wireless power supply system. FIG. 3 schematically illustrates an example of a flowchart showing the details of the procedure in the case of the initial power supply and the distribution of the power supply signal. FIG. 4 schematically illustrates an example of an outline in which a power receiving device generates a modulated signal obtained by modulating a received carrier and transmits the modulated signal to a power supply device. FIG. 5 schematically illustrates an example of a flowchart showing a procedure for estimating a propagation coefficient. FIG. 6 schematically illustrates an example of the phase obtained from the preamble portion. FIG. 7 schematically illustrates an example of the amplitude obtained from the preamble portion. FIG. 8 schematically illustrates an example of an outline of a wireless power feeding system including a power receiving device including a plurality of antenna elements. FIG. 9 schematically illustrates an example of an outline of a wireless power supply system that simultaneously supplies power to a plurality of power receiving apparatuses.

An embodiment according to one aspect of the present invention (hereinafter, also referred to as “the present embodiment”) will be described below with reference to the drawings. However, the present embodiment described below is merely an example of the present invention in every respect. It goes without saying that various improvements and modifications can be made without departing from the scope of the invention. That is, in implementing the present invention, a specific configuration according to the embodiment may be appropriately adopted.

§1 Application Example An example of a scene to which the present invention is applied will be described with reference to FIG. FIG. 1 schematically illustrates an example of the outline of the wireless power supply system 1. As shown in FIG. 1, the wireless power supply system 1 includes a power supply device 2 and a power receiving device 51. The power supply device 2 includes an array antenna 3 formed from a plurality of antenna elements 3A. On the other hand, the power receiving device 51 includes an antenna 52.

As shown in FIG. 1, the power supply device 2 includes a signal generator 4 that generates a power supply signal. Further, the power supply device 2 is provided with a propagation coefficient estimation unit 8 for estimating a propagation coefficient H _i of radio waves between the antenna 52 of the i-th antenna element 3A and the power receiving device 51 of the array antenna 3. Here, the propagation coefficient is a coefficient representing the amount of attenuation and the amount of phase change of the radio wave when the radio wave propagates between the transmitting and receiving antennas.

Further, the power supply device 2 includes on the basis of the propagation coefficients H _i, the weight calculating unit 9 calculates the weight W _i for adjusting the phase and amplitude of the power supply signal generated in the signal generator 4. Weight W _i is a counterpart for each antenna element 3A, is set to be the relationship of conjugation to the propagation coefficients H _i.

  In addition, the power supply device 2 adjusts the phase and amplitude of the power supply signal by multiplying the weight calculated by the weight calculation unit 9 by the power supply signal generated by the signal generator 4, and transmits the adjusted power supply signal to each antenna element 3A. And a power supply signal distribution unit 11 for distributing the power to the power supply.

  Then, in the power supply device 2, each of the antenna elements 3 </ b> A receives the power supply signal distributed in the power supply signal distribution unit 11 and transmits the distributed power supply signal to the antenna 52 of the power reception device 51, whereby the power reception device 51 Power supply.

  That is, the wireless power supply system 1 as described above appropriately adjusts the phase and amplitude of the power supply signal according to the propagation environment between each antenna element 3A of the power supply device 2 and the antenna 52 of the power reception device 51, It is possible to improve power supply efficiency and maximize power supply.

§2 Configuration Example Next, an example of the wireless power supply system according to the present embodiment will be described. As shown in FIG. 1, the wireless power supply system 1 includes a power supply device 2 and a power receiving device 51. Here, the wireless power supply system 1 is an example of the “wireless power supply system” of the present invention. The power supply device 2 is an example of the “wireless power supply device” of the present invention. The power receiving device 51 is an example of the “power supply target device” of the present invention. The power supply device 2 is, for example, an RFID reader, and the power receiving device 51 is, for example, an RFID tag. Further, the power receiving device 51 may include various sensor elements for detecting a predetermined physical quantity.

  The power supply device 2 includes an array antenna 3. The array antenna 3 is formed from a plurality of regularly arranged antenna elements. The power supply device 2 includes a signal generator 4 that generates a power supply signal. Here, the signal generator 4 is an example of the “feeding signal generating unit” of the present invention. The power supply device 2 includes an RF (Radio Frequency) transmission / reception circuit 5 that processes signals transmitted and received via the array antenna 3. Although not shown, the power supply device 2 includes a controller and a memory such as a ROM (Read Only Memory) or a RAM (Random Access Memory).

Here, the RF transmitting and receiving circuit 5 transmits and receives RF (R
An audio frequency (audio frequency) signal and a BB (Base Band) signal can be mutually converted. Further, the RF transmission / reception circuit 5 also performs, for example, A / D (Analogue / Digital) conversion processing. Through such mutual conversion processing, low-speed digital processing can be performed in the power supply device 2. When receiving a modulated signal obtained by modulating a carrier transmitted from the array antenna 3, the RF transmitting / receiving circuit 5 also performs a process of demodulating the modulated signal. Further, the RF transmission / reception circuit 5 is an example of the “demodulation unit” of the present invention.

In addition, as shown in FIG. 1, the power supply device 2 includes a propagation coefficient estimating unit 8 that estimates a propagation coefficient of a radio wave between the antenna element 3A of the array antenna 3 and the antenna 52 of the power receiving device 51. The propagation coefficient estimating unit 8 is an example of the “propagation coefficient calculating unit” of the present invention. Here, the propagation coefficient is a coefficient representing the amount of attenuation and phase change of a radio wave when the radio wave propagates between the transmitting and receiving antennas. For example, the propagation coefficient H _i between the i-th antenna element 3A and the antenna 52 is expressed by the following equation (1).

H _i = C _i exp (jγ _i ) (1)

Here, j is an imaginary unit, γ _i represents the amount of rotation of the phase of the radio wave on the propagation path, and C _i represents the attenuation of the amplitude of the radio wave on the propagation path.

In the present embodiment, the above-described propagation coefficient _Hi is estimated according to the following equation (2).

The power supply device 2, based on the propagation coefficient H _i of the radio wave which is calculated according to equation (2), the weight calculation unit that calculates the weight W _i for adjusting the phase and amplitude of the power supply signal generated in the signal generator 4 9 is provided. Here, the weight calculator 9 is an example of the “weight calculator” of the present invention. The weight _Wi is calculated according to the following equation (3).

Here, m represents the number of power feeds, and N represents the total number of antenna elements 3A. Weight W _i, as shown in equation (3), are set so that the propagation coefficient H _i and the conjugate. The weight W _i is a value obtained by adding the squares of all weights W _i is set to be 1.

Further, the power supply device 2 includes a storage unit 10 for storing the weight W _i calculated in the weight calculating unit 9 in the memory. Here, the storage unit 10 is an example of the “storage unit” of the present invention. The power supply device 2, the weight W _i calculated in the weight calculating unit 9 adjusts the phase and amplitude of the feeding signal by multiplying the power supply signal generated in the signal generator 4, the antenna is adjusted supply signal A power supply signal allocating unit 11 for allocating to the element 3A is provided. Here, the power supply signal distribution unit 11 is an example of the “power supply signal distribution unit” of the present invention. The power P _i distributed to the i-th antenna element 3A in the power supply signal distribution unit 11 and supplied to the power receiving device 51 is represented by the following equation (4).

  The power feeding device 2 is configured such that the controller executes a control program stored in a memory, and thereby the array antenna 3, the signal generator 4, the RF transmitting / receiving circuit 5, the propagation coefficient estimating unit 8, the weight calculating unit 9, the storage unit 10 , The processing in the power supply signal distribution unit 11 is realized.

  On the other hand, the power receiving device 51 includes an antenna 52. The power receiving device 51 is supplied with power by receiving the power supply signal transmitted from the power supply device 2 via the antenna 52. The power receiving device 51 includes an RF transmitting / receiving circuit 53.

  The RF transmitting and receiving circuit 53 provided in the power receiving device 51 includes a receiving circuit 55 having a switch 54, and processes a power supply signal received from the power supply device 2 via the antenna 52 and a signal to be transmitted to the power supply device 2. I do. Here, the receiving end circuit 55 is an example of the “modulated signal generating means” of the present invention. Although not shown, the power receiving device 51 includes a controller and a memory. The controller of the power receiving device 51 does not generate a transmission signal using its own oscillator. The controller instead controls the switch of the receiving end circuit 55 to open and short the receiving end circuit 55, modulates the received signal received from the power supply device 2, and transmits the modulated signal to the power supply device 2. Further, the controller can control a switch of the receiving end circuit 55, modulate a received radio wave based on a signal generated or detected in the power receiving device 51, and transmit the modulated signal. The power receiving device 51 is a batteryless device having no battery.

Next, an operation example of the wireless power supply system 1 will be described. In the wireless power supply system 1, the following operations are realized by the controller of the power supply device 2 and the controller of the power receiving device 51 executing control programs stored in the memories of the respective devices.

  FIG. 2 schematically illustrates an example of a flowchart illustrating an outline of the operation of the wireless power supply system 1. Note that the processing procedure described below is merely an example, and each processing may be changed as much as possible. Further, in the processing procedure described below, steps can be omitted, replaced, and added as appropriate according to the embodiment.

(Step S101)
As shown in FIG. 2, in step S101, the signal generator 4 generates an m-th power supply signal. The power supply signal is generated such that its power becomes the upper limit of the limit value specified by the Radio Law, for example.

(Step S102)
In step S102, in the power supply signal distribution unit 11, the power supply signal is adjusted by multiplying the power supply signal generated by the signal generator 4 by a weight _Wi (m) represented by Expression (3). The adjusted feed signal is distributed to each antenna element 3A. For example, the power feeding signal weights W _{1 (m)} is multiplied by the power supply signal weights W _{1 (m)} is multiplied is allocated to the first antenna element 3A. Next, the power supply signal is multiplied by the weight W ₂ (m), and the weight W ₂ (m) is multiplied.
The feed signal multiplied by m) is distributed to the second antenna element 3A. Such distribution of the power supply signal is executed corresponding to each of the antenna elements 3A.

However, if the initial feeding (m = 1), the wireless power supply system 1 calculates the weight _W i (1) as follows in step S102. FIG. 3 schematically illustrates an example of a flowchart illustrating details of a procedure for calculating the weight _Wi (1) in the case of the first power supply. The processing procedure described below is merely an example, and each processing may be changed as much as possible. Further, in the processing procedure described below, steps can be omitted, replaced, or added as appropriate according to the embodiment.

(Step S102-1)
As shown in FIG. 3, the weight calculator 9 selects an initial value of the weight for distributing the power supply signal to the i-th antenna element 3A from the weight candidate values. Here, the weight candidate values are prepared in advance. In addition, the selection of the initial value of the weight may be selected at random, or may be selected according to a predetermined method.

(Step S102-2)
In step S102-2, the power supply signal generated by the signal generator 4 is multiplied by the initial value of the weight, and the power supply signal multiplied by the initial value of the weight is distributed to each antenna element 3A. Such distribution of the power supply signal is executed corresponding to each of the antenna elements 3A.

(Step S102-3)
In step S102-3, the distributed power supply signal is converted to a high frequency in the RF transmitting / receiving circuit 5 before reaching the antenna element 3A. Then, in each antenna element 3 </ b> A, a power supply radio wave is generated from a high frequency, and the power supply radio wave is transmitted to the power receiving device 51, thereby performing power supply.

(Step S102-4)
In step S102-4, a request for a signal is made from the power supply apparatus 2 to the power receiving apparatus 51. The signal request is realized by transmitting a carrier from each antenna element 3A to the antenna 52 of the power receiving device 51.

  The power receiving device 51 receives the carrier transmitted from the power feeding device 2. In the power receiving device 51, the opening and closing of the switch 54 of the receiving end circuit 55 is controlled, and the receiving end circuit 55 is opened and short-circuited to generate a modulation signal that modulates the received carrier. 2 is sent. FIG. 4 schematically illustrates an example of an outline in which the power receiving device 51 generates a modulated signal obtained by modulating a received carrier, and transmits the modulated signal to the power supply device 2. However, in the power receiving device 51, a modulated signal in which the phase and amplitude of the carrier are modulated is generated, and a modulated signal in which the frequency of the carrier is modulated is not generated.

(Step S102-5)
In step S102-5, in response to the signal request to the power receiving device 51 executed in step S102-4, the power supply device 2 determines whether or not a signal has been received from the power receiving device 51.

(Step S102-6)
In step S102-6, when it is determined in step S102-5 that the modulated signal of the carrier is received from the power receiving device 51, the propagation coefficient estimating unit 8 determines whether the antenna element 3A between the antenna element 3A and the antenna 52 of the power receiving device 51 is present. The propagation coefficient _Hi is estimated based on equation (2). Here, the received signal from the power receiving device 51 to be used in the case of estimation of the propagation coefficient H _i the preamble portion of the received signal is used. In addition, the replica of the received signal previously received from the power receiving device 51 in Expression (2) is generated in advance and stored in the memory. The modulated signal received from the power receiving device 51 is subjected to A / D conversion processing and conversion to a BB signal in the RF transmission / reception circuit 5 and demodulated. The propagation coefficient is estimated by a digital circuit (not shown) provided in the power supply device 2.

(Step S102-7)
In step S102-7, the weight calculation section 9, based on the propagation coefficient _{H i} estimated in step S102-6, the weight _W i (1) is calculated. The method of calculating the weight from the propagation coefficient follows equation (3).

(Step S102-8)
In step S102-8, the storage unit 10, calculated weights _W i (1) is stored in the memory.

(Step S102-9)
In step S102-9, when it is determined in step S102-5 that no modulated signal of the carrier has been received from the power receiving device 51, it is determined whether all the weight candidate values prepared in advance have been selected. When it is determined that all the weight candidate values have been selected, the initial setting of the weight W _i (1) by which the power supply signal is multiplied ends. On the other hand, when it is determined that all of the weight candidate values have not been selected, the process returns to step S102-1.

  Steps S102-1 to S102-9 are executed at the time of the first power supply in step S102.

(Step S103)
In step S103, the distributed power supply signal is converted to a high frequency in the RF transmitting / receiving circuit 5 before reaching the antenna element 3A. Then, in each antenna element 3 </ b> A, a power supply radio wave is generated from a high frequency, and the power supply radio wave is transmitted to the power receiving device 51, thereby performing power supply. The power P _i supplied from the i-th antenna element 3A to the power receiving device 51 is represented by Expression (4).

(Step S104)
In step S104, a request for a signal is made from the power supply apparatus 2 to the power receiving apparatus 51. The signal request is realized by transmitting a carrier from each antenna element 3A to the antenna 52 of the power receiving device 51.

The power receiving device 51 receives the carrier transmitted from the power feeding device 2. In the power receiving device 51, the opening and closing of the switch 54 of the receiving end circuit 55 is controlled, and the receiving end circuit 55 is opened and short-circuited to generate a modulation signal that modulates the received carrier. 2 is sent. However, in the power receiving device 51, a modulated signal in which the phase and amplitude of the carrier are modulated is generated, and a modulated signal in which the frequency of the carrier is modulated is not generated.

(Step S105)
In step S105, the power supply device 2 determines whether a signal has been received from the power receiving device 51 in response to the signal request to the power receiving device 51 executed in step S104.

(Step S106)
In step S106, in step S105, when the modulation signal of the carrier from the power receiving device 51 is determined to have been received, the propagation coefficient H _i between the propagation coefficient estimation unit 8 and the respective antenna elements 3A and antenna 52 of the power receiving device 51 (M + 1) is estimated based on equation (2). Here, the received signal from the power receiving device 51 to be used in the case of estimation of the propagation coefficient H _i the preamble portion of the received signal is used. In addition, the replica of the received signal received from the power receiving device 51 in the past in Expression (2) is generated in advance and stored in the memory. The modulated signal received from the power receiving device 51 is subjected to A / D conversion processing and conversion to a BB signal in the RF transmission / reception circuit 5 and demodulated. The propagation coefficient is estimated by a digital circuit (not shown) provided in the power supply device 2.

(Step S107)
In step S107, the weight calculator 9, based on the estimated propagation coefficients _H i (m + 1) in step S106, the weight _W i (m + 1) is calculated. The method of calculating the weight from the propagation coefficient follows equation (3).

In step S107, the weight calculator 9, without using the estimated propagation coefficients _H i (m + 1) in step S106, the estimated in the past, based on the weight _{W i} stored in the memory, the prediction weights _{W i} '(M + 1) is calculated. The prediction weight _Wi '(m + 1) is calculated according to the following equation (5).

Here, the weight prediction coefficient β _j used in the equation (5) is a coefficient optimized for each power supply frequency so that the prediction error W _error calculated according to the following equation (6) is minimized.

(Step S108)
In step S108, if it is determined from the power receiving device 51 and the reception signal is not in step S105, the propagation coefficient _H i (m + 1) weight based on the _W i (m + 1) is not calculated, as shown in Equation (5) prediction Only the weights _Wi '(m + 1) are calculated.

(Step S109)
In step S109, the calculated weight _Wi (m + 1) and the predicted weight _Wi '(m + 1) are stored in the memory in the storage unit 10. Then, returning to step S101, the signal generator 4 generates the (m + 1) th power supply signal. Then, the above steps are repeatedly executed. However, if it is determined in step S105 that no modulated signal has been received from the power receiving device 51, the weight by which the power supply signal generated by the signal generator 4 is multiplied is replaced with the predicted weight W _i ′ (m + 1).

[Action / Effect]
In the wireless power supply system 1 as described above, the power supply signal is adjusted by multiplying the power supply signal generated by the signal generator 4 by a weight, and the adjusted power supply signal is distributed to each antenna element 3A. The weight used for the adjustment of the power supply signal is calculated by calculating the propagation coefficient between each antenna element 3A of the power supply device 2 and the antenna 52 of the power reception device 51 according to the equation (2). It is calculated according to equation (3) so as to be conjugate. The adjustment is performed for each antenna element 3A. That is, the power supply device 2 adjusts the phase of the power supply signal by multiplying the power supply signal generated in the signal generator 4 by a weight in consideration of the propagation environment between each antenna element 3A and the power reception device 51. Each feed radio wave received by the antenna 52 of the power receiving device 51 from each antenna element 3A of the feed device 2 has the same phase. That is, the wireless power supply system 1 can improve the power supply efficiency to the power receiving device 51.

Further, according to the wireless power supply system 1 as described above, the amplitude of the power supply signal is adjusted by multiplying the power supply signal by the weight in consideration of the propagation environment. Further, the supply power P _i distributed to the i-th antenna element 3A after being adjusted and supplied to the power receiving device 51 is, as shown in Expression (4), the value of the power supply signal generated by the signal generator 4. The value is obtained by multiplying the square of the amplitude by the square of the weight. Here, taking the sum of both sides of the equation (4), when obtaining the sum of the supply power supplied from each antenna element 3A to the power receiving device 51, since the square sum of the weights W _i is 1 (formula (3 )), The sum of the supplied power is equal to the square of the amplitude of the power supply signal generated in the signal generator 4. That is, the wireless power supply system 1 adjusts the amplitude of the power supply signal transmitted via each antenna element 3A so that the power supply generated by the signal generator 4 is supplied to the power receiving device 51 without increasing or decreasing. You are doing. By the way, the supply power generated by the signal generator 4 is the upper limit of the limit value defined by the Radio Law, as shown in step S101. That is, in the wireless power supply system 1 described above, the maximum supply power that satisfies the provisions of the Radio Law is generated in the signal generator 4, and the maximum supply power is supplied to the power receiving device 51.

  In the case of the wireless power supply system 1 as described above, a signal request is made once from the power supply device 2 to the power receiving device 51, and the propagation coefficient is calculated based on the signal received from the power receiving device 51. Therefore, the propagation coefficient is calculated quickly. Therefore, a decrease in the throughput in the power supply device 2 is suppressed, and the power supply time is saved.

  In the wireless power supply system 1 as described above, a request for a signal from the power supply device 2 to the power reception device 51 is performed each time power is supplied. Therefore, in the wireless power supply system 1 as described above, even if the propagation environment between the antenna element 3A of the power feeding device 2 and the antenna 52 of the power receiving device 51 changes, the change of the propagation environment quickly occurs. The detected radio wave supplied from the antenna element 3A is quickly adjusted. That is, a change in the propagation environment between the power supply device 2 and the antenna 52 of the power reception device 51 is promptly dealt with, and a decrease in the reliability of communication between the power supply device 2 and the power reception device 51 is suppressed.

In the wireless power supply system 1 as described above, processes for adjusting the phase and the amplitude of the power supply signal, such as the calculation of the propagation coefficient and the calculation of the weight, are executed on the power supply device 2 side, not on the power reception device 51. . Here, unlike the wireless power supply system 1 described above, when processing for adjusting the phase and amplitude of a power supply signal such as calculation of a propagation coefficient and calculation of a weight is performed on the power receiving device 51 side, the power receiving device 51 side Needs to be transmitted to the power supply device 2 side. When such transmission is performed, it is preferable to increase the SNR of the transmission radio wave. Therefore, the power receiving device 51 needs to perform signal processing such as amplification of a transmission signal and removal of noise included in the transmission signal. In addition, these signal processes require power. On the other hand, according to the wireless power supply system 1 as described above, such signal processing is unnecessary. Therefore, the power consumption of the power receiving device 51 can be reduced. Therefore, the wireless power supply system 1 as described above is, of course, an effective system when the power receiving device 51 is a device without a battery.

  In the case of the wireless power supply system 1 as described above, communication between the power supply device 2 and the power receiving device 51 is interrupted, and a signal from the power receiving device 51 in response to a request signal from the power supply device 2 cannot be received. Even if it is not possible, the weight can be predicted using the weight calculated in the past and stored in the memory. Then, the phase and amplitude of the power supply signal can be adjusted using the predicted weight.

Further, if the wireless power supply system 1 as described above, the weighting prediction coefficient beta _j is the prediction error W _error is optimized for each feeding times to a minimum. Therefore, even when the propagation coefficient cannot be calculated because the signal from the power receiving device 51 cannot be received in response to the request signal from the power supply device 2, the prediction weight _Wi ′ is calculated using the weight prediction coefficient β _j. (M + 1) can be calculated with high accuracy. Even when the propagation environment changes, the accuracy of the prediction weight W _i ′ (m + 1) is maintained because the weight prediction coefficient β _j is optimized each time.

  In response to a signal request from the power supply device 2, the power reception device 51 modulates the carrier transmitted from the power supply device 2 by opening and closing the switch 54 of the reception circuit 55, and transmits the modulated signal to the power supply device 2. I have. In such a signal transmission method, a signal can be transmitted to the power supply device 2 without using an oscillator, so that power saving is realized. In addition, such a signal transmission method can transmit a modulation signal responsive to a request signal to the power supply apparatus 2 even if the power receiving apparatus 51 does not have a battery or does not include an oscillator. . Therefore, the signal transmission method is a highly convenient signal transmission method.

  Further, in the signal transmission method as described above, when the power receiving device 51 includes various sensor elements that detect a predetermined physical quantity, the power receiving device 51 performs a signal transmission based on a signal corresponding to the predetermined physical quantity detected by the sensor element. Thus, it is possible to control the opening and closing of the switch 54 of the receiving end circuit 55 to generate a modulated signal obtained by modulating the carrier received from the power supply device 2. That is, when responding to the power supply device 2, the power receiving device 51 can also transmit information detected by its own sensor together with the response signal. That is, when the power receiving device 51 includes a sensor element, the wireless power feeding system 1 described above can save time and effort for transmitting information detected by the sensor to the power feeding device 2.

  In addition, the power supply device 2 receives a modulated signal having the same frequency as the carrier frequency from the power receiving device 51. Therefore, when calculating the propagation coefficient, the power supply apparatus 2 does not need to consider the difference between the carrier frequency and the modulation signal frequency. That is, the propagation coefficient is easily estimated.

In the wireless power supply system 1 as described above, when estimating the propagation coefficient, the preamble portion of the signal received from the power receiving device 51 is used. Therefore, the wireless power supply system 1 can easily estimate the propagation coefficient without adding a new process to the existing communication protocol.

§4 Modifications Although the embodiment of the present invention has been described in detail, the above description is merely an example of the present invention in every respect. It goes without saying that various improvements and modifications can be made without departing from the scope of the invention. For example, the following changes are possible. In the following, the same reference numerals are used for the same components as those in the above-described embodiment, and the description of the same points as in the above-described embodiment is omitted as appropriate. The following modifications can be combined as appropriate.

<4.1>
In the wireless power supply system 1 described above, the power receiving device 51 may include a battery. Here, the battery is an example of the “power storage unit” of the present invention. When the power receiving device 51 receives a signal request from the power supply device 2 in step S102-4 or step S104, the power reception device 51 generates and transmits a modulated signal obtained by modulating the carrier received from the power supply device 2. Instead, a signal is generated in an oscillator built in its own controller and transmitted to the power supply device 2. Here, when the oscillator of the signal generator 4 of the power supply device 2 and the oscillator of the power reception device 51 generate signals having different frequencies, the frequency of the radio wave of the request signal transmitted from the power supply device 2 to the power reception device 51 and the request signal Accordingly, the frequency of the radio wave transmitted from the power receiving device 51 to the power supply device 2 is different. When the frequency of the radio wave transmitted from the power supply device 2 to the power reception device 51 is different from the frequency of the radio wave transmitted from the power reception device 51 to the power supply device 2, the propagation coefficient estimation unit 8 replaces the equation (2). in accordance with estimation procedure below may estimate a propagation coefficient H _i between the antenna 52 of the array antenna 3 and the power receiving device 51. Figure 5 illustrates an example of a flowchart showing the procedure of estimating the propagation coefficient H _i schematically. Note that the estimation procedure described below is merely an example, and each processing may be changed as much as possible. Further, in the estimation procedure described below, steps can be omitted, replaced, and added as appropriate according to the embodiment.

(Step S201)
In step S201, the propagation coefficient estimating unit 8 extracts a preamble portion of a signal input from the RF transmitting / receiving circuit 5 of the power supply apparatus 2 to the i-th antenna element 3A. Then, the phase θ _i (k) and the amplitude A _i (k) of the preamble portion are obtained. FIG. 6 schematically illustrates an example of the phase θ _i (k) obtained from the preamble portion. FIG. 7 schematically illustrates an example of the amplitude A _i (k) obtained from the preamble portion. Here, i is the index of the antenna element 3A, and k is the sample index of the extracted preamble portion.

(Step S202)
In step S202, the propagation coefficient estimation unit 8, the phase gamma _i of the propagation coefficient _{H i} which is expressed by the equation (1) is calculated. Here, it is known that the following equation (7) holds between the phase θ _i (k) and the phase γ _i of the propagation coefficient H _i .

Therefore, the propagation coefficient estimating unit 8 can generate a regression line related to k of the phase θ _i (k) from the data shown in FIG. 6, and calculate the phase γ _i using the regression line.

(Step S203)
In step S203, the propagation coefficient estimation unit 8, the amplitude _{C i} of the propagation coefficient _{H i} which is expressed by the equation (1) is calculated. Here, between the amplitude C _i of the amplitude A _{i (k)} and the propagation coefficient H _i of preamble, it is known that holds the relationship of formula (8) below.

The above-mentioned noise, for example if deemed uniformly varies noise around zero, the amplitude C _i according to the following equation (9), is calculated in a simple manner.

Accordingly, the propagation coefficient estimation unit 8, by substituting the equation (9) the data shown in Figure 7, it is possible to calculate the amplitude C _i.

[Action / Effect]
In such a wireless power supply system, even when power is not supplied from the power supply device 2 to the power reception device 51, the power reception device 51 generates predetermined power such as operating an oscillator, amplifying a signal, and removing noise. Necessary processing can be performed. Further, communication can be performed between the power supply device 2 and the power receiving device 51. In addition, the power supply apparatus 2 receives a response signal having a frequency different from the request signal from the power receiving apparatus 51, but can estimate a propagation coefficient according to Expressions (7) and (9). That is, such a wireless power supply system is a highly convenient system that can estimate the propagation coefficient and adjust the power supply signal even for the power receiving device 51 that transmits response signals of various frequencies.

<4.2>
Further, the antenna 52 of the power receiving device 51 of the wireless power supply system 1 may be an array antenna formed by a plurality of antenna elements 52A. FIG. 8 schematically illustrates an example of the outline of the wireless power supply system 1 including the power receiving device 51 including a plurality of antenna elements 52A. In the case of the power receiving device 51 as shown in FIG. 8, the RF transmitting / receiving circuit 53 is provided so as to correspond to each of the plurality of antenna elements 52A. In the wireless power supply system illustrated in FIG. 8, the propagation coefficient is estimated by the number of combinations of each antenna element 3A of the power supply device 2 and each antenna element 52A of the power reception device 51. Then, based on the propagation coefficient, the power supply signal transmitted from each antenna element 3A of power supply device 2 to each antenna element 52A of power reception device 51 is adjusted.

[Action / Effect]
In the wireless power supply system 1 as described above, the propagation path (path) of the radio wave between the power supply device 2 and the power receiving device 51 is increased, and the radio wave propagated through a plurality of paths can be concentrated on the power receiving device 51. Therefore, the power supply efficiency to the power receiving device 51 increases.

<4.3>
The power supply device 2 of the wireless power supply system 1 may supply power to a plurality of power reception devices 51. FIG. 9 schematically illustrates an example of the outline of the wireless power supply system 1 that supplies power to the plurality of power receiving devices 51. Here, the antenna 52 included in each power receiving device 51 may be a single antenna or an array antenna formed from a plurality of antenna elements as in Modification <4.2>. In the wireless power feeding system shown in FIG. 9, the propagation coefficient is estimated by the number of combinations of each antenna element 3A of the power feeding device 2 and each antenna element of each power receiving device 51. Then, a weight is calculated based on the propagation coefficient, and a power supply signal transmitted from each antenna element 3A of the power supply device 2 to each antenna element 52A of each power reception device 51 is adjusted based on the weight.

[Action / Effect]
The wireless power supply system 1 as described above is a highly convenient system that can supply power to a plurality of power receiving devices 51.

  Further, in the RF transmission / reception circuit 5 of the power supply device 2 or the RF transmission / reception circuit 53 of the power receiving device 51, mutual conversion between the RF signal and the BB signal is not performed, and the RF signal is directly converted into an A / D signal by a high-speed A / D conversion process. It may be converted. With such a wireless power supply system 1, the number of circuits for performing the mutual conversion process between the RF signal and the BB signal is reduced, and the size of the RF transmitting and receiving circuit can be reduced. Therefore, the power supply device 2 and the power receiving device 51 can be reduced in size. Also, parts costs can be reduced.

  Further, in the power supply device 2 of the wireless power supply system 1 described above, the estimation of the propagation coefficient is performed in the digital circuit, but the estimation of the propagation coefficient may be performed in the analog circuit. With such a wireless power supply system 1, a propagation coefficient can be directly estimated from an RF signal received by an antenna and used for estimating a propagation coefficient without performing A / D conversion processing. Therefore, the estimation of the propagation coefficient is performed more easily.

  The embodiments and modifications disclosed above can be combined with each other.

In the following, the components of the present invention are described with reference numerals in the drawings so that the components of the present invention can be compared with the configurations of the embodiments.
<Invention 1>
A wireless power supply (2) including an array antenna (3) formed from a plurality of antenna elements (3A),
Power supply signal generation means (4) for generating a power supply signal;
Propagation coefficient calculation means (8) for calculating respective propagation coefficients between the plurality of antenna elements (3A) and the antenna (52) of the power supply target device (51);
Based on the respective propagation coefficients calculated by the propagation coefficient calculation means (8), the phase and the amplitude of the power supply signal generated by the power supply signal generation means (4) are converted to the plurality of antenna elements (3A). Weight calculating means (9) for calculating a weight to be adjusted for each;
Adjusting the phase and the amplitude of the power supply signal generated by the power supply signal generation means (4) for each of the plurality of antenna elements (3A) based on the weight calculated by the weight calculation means (9); Feed signal distribution means (11) for distributing the feed signal adjusted for each of the plurality of antenna elements (3A) to the plurality of antenna elements (3A);
The plurality of antenna elements (3A) forming the array antenna (3) convert the distributed power supply signal into a power supply radio wave and transmit the power supply radio wave to the power supply target device (51).
Wireless power supply device (2).
<Invention 2>
A request signal requesting a response to the power supply target device (51) is transmitted to the power supply target device (51) via the plurality of antenna elements (3A) forming the array antenna (3), and the request signal is transmitted to the power supply target device (51). Is received from the power supply target device (51) via the plurality of antenna elements (3A),
The propagation coefficient calculation means (8) calculates respective propagation coefficients between the plurality of antenna elements (3A) and the antenna (52) of the power supply target device (51) based on the received response signal. ,
The wireless power supply device (2) according to the first aspect.
<Invention 3>
The transmission of the request signal to the power supply target device (51) and the reception of the response signal from the power supply target device (51) to the transmitted request signal are performed when power is supplied to the power supply target device (51). Performed each time,
The wireless power supply device (2) according to the second aspect.
<Invention 4>
Storage means (10) for sequentially storing the weights calculated by the weight calculation means (9);
When the response signal is not received, the weight calculation means (9) predicts a weight based on a predetermined number of weights stored by the storage means (10), and calculates the propagation coefficient using the predicted weight. Substitute the weight calculated based on
A wireless power supply device (2) according to the invention 2 or 3.
<Invention 5>
The prediction of the weight is performed by multiplying a predetermined number of weights stored by the storage unit (10) by a weight prediction coefficient corresponding to each of the predetermined number of weights,
The weight calculation means (9) predicts the weight in addition to calculating the weight based on the propagation coefficient when the response signal is received before receiving the response signal, and Update the weight prediction coefficient so that the difference between the weight based on the calculated propagation coefficient and the predicted weight is minimized,
The wireless power supply device (2) according to the fourth aspect.
<Invention 6>
The power supply signal generating means (4) generates a power supply signal to be transmitted to a plurality of power supply target devices (51).
The wireless power supply device (2) according to any one of Inventions 1 to 5.
<Invention 7>
An antenna (52), and a modulation signal generating means (55) for generating a modulation signal obtained by modulating the received radio wave when receiving a radio wave from a device outside the system via the antenna (52). Power supply target device (51);
The wireless power supply device (2) according to any one of Inventions 1 to 6, wherein the demodulation means (5) demodulates the modulation signal when receiving the modulation signal from the power supply target device (51). ) Further comprising a wireless power supply device (2) further comprising:
Wireless power supply system (1).
<Invention 8>
The power supply target device (51) further includes a power storage unit.
A wireless power supply system (1) according to a seventh aspect.
<Invention 9>
The antenna (52) included in the power supply target device (51) is formed from a plurality of antenna elements (52A).
A wireless power supply system (1) according to invention 7 or 8.

DESCRIPTION OF SYMBOLS 1 ... Wireless power supply system 2 ... Power supply device 3 ... Array antenna 3A ... Antenna element 4 ... Signal generator 5 ... RF transmission / reception circuit 8 ... Propagation coefficient estimation part 9 ... Weight calculation unit 10 Storage unit 11 Feed signal distribution unit 51 Power receiving device 52 Antenna 52A Antenna element 53 RF transmission / reception circuit 54 Switch 55・ Reception circuit

Claims (9)

A wireless power supply device including an array antenna formed from a plurality of antenna elements,
Power supply signal generation means for generating a power supply signal;
Propagation coefficient calculation means for calculating respective propagation coefficients between the plurality of antenna elements and the antenna of the device to be fed,
Weights for calculating weights for adjusting the phase and amplitude of the feed signal generated by the feed signal generating means for each of the plurality of antenna elements based on the respective propagation coefficients calculated by the propagation coefficient calculating means Calculation means;
Based on the weights calculated by the weight calculation means, the phase and the amplitude of the power supply signal generated by the power supply signal generation means are adjusted for each of the plurality of antenna elements, and adjusted for each of the plurality of antenna elements. Power supply signal distribution means for distributing the supplied power signal to the plurality of antenna elements,
The plurality of antenna elements forming the array antenna convert the distributed power supply signal into a power supply radio wave, and transmit the power supply radio wave to the power supply target device.
Wireless power supply. A request signal for requesting a response to the power supply target device is transmitted to the power supply target device via the plurality of antenna elements forming the array antenna, and a response signal from the power supply target device to the request signal, Received through a plurality of antenna elements,
The propagation coefficient calculation means, based on the received response signal, calculates respective propagation coefficients between the plurality of antenna elements and the antenna of the power supply target device,
The wireless power supply device according to claim 1. The transmission of the request signal to the power supply target device, and the reception of the response signal from the power supply target device to the transmitted request signal is performed every time power is supplied to the power supply target device,
The wireless power supply device according to claim 2. Further comprising storage means for sequentially storing the weights calculated by the weight calculation means,
When the response signal is not received, the weight calculation unit predicts a weight based on the predetermined number of weights stored by the storage unit, and is calculated based on the propagation coefficient with the predicted weight. Substitute weights,
The wireless power supply device according to claim 2. The weight prediction is performed by multiplying a predetermined number of weights stored by the storage unit by a weight prediction coefficient corresponding to each of the predetermined number of weights,
The weight calculation means, when receiving the response signal earlier than when not receiving the response signal, in addition to calculating the weight based on the propagation coefficient, predicts the weight, the calculated propagation Updating the weight prediction coefficient so that the difference between the weight based on the coefficient and the predicted weight is minimized,
The wireless power feeding device according to claim 4. The power supply signal generation unit generates a power supply signal to be transmitted to a plurality of power supply target devices,
The wireless power supply device according to claim 1. An antenna, and a power supply target device having a modulation signal generating unit configured to generate a modulation signal obtained by modulating the received radio wave when a radio wave is received from a device outside the system via the antenna.
The wireless power supply device according to claim 1, further comprising: a demodulation unit configured to demodulate the modulated signal when receiving the modulated signal from the power supply target device. Comprising,
Wireless power supply system. The power supply target device further includes a power storage unit,
A wireless power supply system according to claim 7. The antenna included in the power supply target device is formed from a plurality of antenna elements,
The wireless power supply system according to claim 7.