Power receiver, wireless power supply system, and wireless power supply method

Abstract

To make an existing IoT apparatus adaptable to wireless power supply.SOLUTION: A power receiver includes: a power supply antenna part having a plurality of power supply antennas that receives electric waves in a plurality of frequency bands assigned to power supply; a switch part that switches and outputs a power supply electric wave received by any power supply antenna that the power supply antenna part has; an external interface part to be connected to an IoT apparatus which is a power receiving target; and a power supply control unit that causes the IoT apparatus to supply the electric wave output from the switch part via the external interface part.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a power receiver, a wireless power feeding system, and a wireless power feeding method. [Background technology]

[0002] There is known a wireless power supply technology for wirelessly supplying power from a power transmitting device to a power receiving device (for example, Patent Document 1). Three frequency bands, 920 MHz, 2.4 GHz, and 5.7 GHz, are allocated as frequencies for wireless power supply. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-18146 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, although the ministerial ordinance was revised to put wireless power supply into practical use, there are few receivers that can support wireless power supply, and in particular, there are almost no IoT devices that can support wireless power supply, such as surveillance cameras, that have both sensor and communication functions. Switching costs are required to replace existing IoT devices with IoT devices that support wireless power supply. Furthermore, since there are multiple frequency bands allocated for wireless power supply, there is a problem that the switching costs are excessive to replace IoT devices that can support all of the bands.

[0005] The present invention has been made in light of the above-mentioned problems, and aims to provide a power receiver, a wireless power supply system, and a wireless power supply method that can make existing IoT devices compatible with wireless power supply. [Means for solving the problem]

[0006] The power receiver of the present invention includes a power supply antenna unit having a plurality of power supply antennas each receiving radio waves in a plurality of frequency bands assigned for power supply, a switch unit which switches and outputs the power supply radio waves received by any of the power supply antennas of the power supply antenna unit, an external interface unit which connects to an IoT device to be powered, and a power supply control unit which supplies power to the IoT device using the radio waves output from the switch unit via the external interface unit.

[0007] The wireless power supply system of the present invention includes the above-described power receiver, and a power supply control server that controls the power transmitter so that radio waves for power supply are transmitted by the power transmitter corresponding to one of a plurality of frequency bands allocated for power supply in response to a request from the power receiver.

[0008] The wireless power supply method of the present invention is a wireless power supply method performed by a power receiver that includes a power supply antenna unit having a plurality of power supply antennas that each receive radio waves in a plurality of frequency bands assigned for power supply, and an external interface unit that connects to an IoT device to be powered, in which a switch unit switches between and outputs the power supply radio waves received by any of the power supply antennas of the power supply antenna unit, and a power supply control unit causes the radio waves output from the switch unit to supply power to the IoT device via the external interface unit. Effect of the Invention

[0009] According to the present invention, existing IoT devices can be made compatible with wireless power supply. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram showing a configuration example of a wireless power supply system 1 according to an embodiment. [Diagram 2] 2 is a block diagram showing a configuration example of a power receiver 30 according to an embodiment. FIG. [Diagram 3] FIG. 11 is a diagram illustrating an example of a power supply condition storage unit 313 according to the embodiment. [Figure 4]4 is a sequence diagram showing a flow of processing performed by the wireless power supply system 1 of the embodiment. [Diagram 5] 4 is a sequence diagram showing a flow of processing performed by the wireless power supply system 1 of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a wireless power supply system 1 and a power supply control server 10 according to an embodiment will be described with reference to the drawings.

[0012] The wireless power supply system 1 will be described with reference to Fig. 1. Fig. 1 is a block diagram showing a configuration example of the wireless power supply system 1 according to an embodiment. As shown in Fig. 1, the wireless power supply system 1 includes, for example, a power supply control server 10, a plurality of power transmitters 20 (power transmitters 20-1 to 20-3, ...), and a plurality of power receivers 30 (power receivers 30-1 to 30-4, ...).

[0013] The power supply control server 10 controls the power transmitter 20 and causes the power transmitter 20 to transmit radio waves for power supply to one or more power receivers 30 present in the power supply area E, thereby performing wireless power supply.

[0014] The power transmitter 20 transmits radio waves for power supply under the control of the power supply control server 10. The power transmitter 20 corresponds to any one of a plurality of frequency bands allocated as frequencies for wireless power supply. In the example of this figure, the power transmitter 20-1 is a power transmitter A that transmits radio waves for power supply having a frequency band A (e.g., 920 MHz band). The power transmitter 20-2 is a power transmitter B that transmits radio waves for power supply having a frequency band B (e.g., 2.4 GHz band). The power transmitter 20-3 is a power transmitter C that transmits radio waves for power supply having a frequency band C (e.g., 5.7 GHz band).

[0015] In each of the multiple frequency bands allocated as frequencies for wireless power supply, the transmission power of the radio waves for power supply that can be transmitted is specified. For example, the transmission power in the 920 MHz band is a smaller output value (e.g., 1 W) than that in other frequency bands. The transmission power in the 5.7 GHz band is a larger output value (e.g., 32 W) than that in other frequency bands. The transmission power in the 2.4 GHz band is a value (e.g., 15 W) between the transmission power in the 920 MHz band and the transmission power in the 5.7 GHz band. In general, a power receiver that is equidistant from a transmitting antenna can receive more power when it receives power transmitted from a transmitting antenna with a larger transmission power.

[0016] When different transmission powers are set for each frequency band, it is possible to select a frequency band to be used for power supply according to the purpose of power supply, and to perform wireless power supply using the selected frequency band. For example, when a small amount of power is to be supplied, wireless power supply in the 920 MHz band with a small transmission power can be used. On the other hand, when a large amount of power is to be supplied, wireless power supply in the 5.7 GHz band with a large transmission power can be used. Alternatively, when power supply is to be completed in a short time, wireless power supply in the 5.7 GHz band with a large transmission power can be used, and when it is possible to spend a long time supplying power, wireless power supply in the 920 MHz band with a small transmission power can be used. In this way, it is possible to use different frequency bands according to the purpose of power supply.

[0017] The power receiver 30 is a power receiving device that receives power for power supply transmitted from the power transmitter 20. The power receiver 30 periodically transmits radio waves including a predetermined specific frequency or radio waves including a specific signal format as a beacon signal. The power receiver 30 transmits the beacon signal from a communication antenna provided in a communication unit 308 (see FIG. 2 ) described later. Alternatively, the power receiver 30 may transmit the beacon signal by short-range wireless communication such as infrared communication. The beacon signal includes information indicating, for example, a device ID that can identify the power receiver 30. The power receiver 30 transmits the beacon signal with a radio wave intensity that can reach a specific range (for example, a range of a radius of several meters to several tens of meters). When the power transmitter 20 receives the beacon signal, it identifies the power receiver 30 corresponding to the received beacon signal and determines that the power receiver 30 is present in its own power supply area E. The power transmitter 20 notifies the power supply control server 10 of the power receiver 30 present in the power supply area E periodically or irregularly. In response to a power supply start request described later, the power supply control server 10 determines the power transmitter 20 that supplies power to the power receiver 30 based on the power supply area E in which the power receiver 30 is present and the power transmitter 20 installed in the power supply area E. As a result, the power transmitter 20 transmits radio waves for power supply. The power receiver 30 receives the radio waves for power supply by receiving the radio waves transmitted by the power transmitter 20.

[0018] The power receiver 30 of this embodiment is connected to an IoT device 31. The power receiver 30 and the IoT device 31 are connected to each other by, for example, a Universal Serial Bus (USB) cable.

[0019] Many USB cables have been developed so that they can be used as power supply cables. For example, USB2.0 can supply a maximum voltage of 5V and a current of 500mA, and is used as the standard output for general USB ports and USB hubs. Also, USB3.0 (or USB3.1Gen1, USB3.2Gen1) can supply a maximum voltage of 5V and a current of 900mA, and is compliant with the standard for high-capacity and / or high-speed power supply called BC1.2 (Battery Charging 1.2). USB3.1Gen2 or USB3.2Gen2 can supply a maximum voltage of 5V and a current of 1.5A (1500mA), which allows for higher output or faster power supply compared to USB2.0 and USB3.0. USB PD (USB Power Delivery) can supply a maximum voltage of 20V and a current of 5A (5000mA). USB PD is widely used in general-purpose devices such as laptops, smartphones, and tablets.

[0020] The power receiver 30 of this embodiment is configured to be connectable to a power supply connector, such as this USB cable, provided on an IoT device 31 as a general-purpose device. The power receiver 30 supplies power based on the power supply radio waves received from the power transmitter 20 to the IoT device 31 via a power supply connector, such as a USB cable. As a result, the wireless power supply system 1 of this embodiment can make existing IoT devices that do not support wireless power supply by themselves compatible with wireless power supply.

[0021] 2 is a block diagram showing a configuration of a power receiver 30 according to an embodiment. The power receiver 30 includes a power supply antenna unit 300, a SW unit 307, a communication unit 308, a power supply control unit 309, a power supply control unit 310, a battery unit 311, an external IF unit 312, and a power supply condition storage unit 313.

[0022] The power supply antenna unit 300 has a plurality of pairs of a power supply antenna and a rectifier circuit. For example, in the example shown in the figure, the power supply antenna unit 300 has a pair of a first power supply antenna unit 301 and a rectifier circuit 302, a pair of a second power supply antenna unit 303 and a rectifier circuit 304, and a pair of a third power supply antenna unit 305 and a rectifier circuit 306. Each pair receives radio waves of different frequency bands as radio waves for power supply, converts the received radio waves from AC to DC, rectifies them, and outputs them.

[0023] For example, the first power supply antenna unit 301 includes an antenna that receives radio waves for power supply in the 920 MHz band. The rectifier circuit 302 is a circuit that converts the radio waves (power) received by the first power supply antenna unit 301 from AC to DC and rectifies the power. The second power supply antenna unit 303 includes an antenna that receives radio waves for power supply in the 2.4 GHz band. The rectifier circuit 304 is a circuit that converts the radio waves (power) received by the second power supply antenna unit 303 from AC to DC and rectifies the power. The third power supply antenna unit 305 includes an antenna that receives radio waves for power supply in the 5.7 GHz band. The rectifier circuit 306 is a circuit that converts the radio waves (power) received by the third power supply antenna unit 305 from AC to DC and rectifies the power.

[0024] The SW unit 307 switches and outputs the power supply radio waves received by any one of the power supply antennas included in the power supply antenna unit 300. The SW unit 307 outputs the power output from any one of the rectifier circuits 302, 304, and 306 to the power supply control unit 310 under the control of the power supply control unit 309.

[0025] The power supply control unit 310 controls the power supply voltage. The power supply control unit 310 includes, for example, a composite power supply IC (PMIC, Power Management IC). The power supply control unit 310 has, for example, an LDO (Low Dropout) function as a linear regulator for keeping the voltage constant, and a DC-DC converter function for stepping up or stepping down the input voltage. The power supply control unit 310 converts the DC power output from the SW unit 307 into DC power having a desired voltage according to the control of the power supply control unit 309, and outputs the converted DC power to the battery unit 311 and / or the external IF unit 312.

[0026] The battery unit 311 includes a power source that supplies power to the power receiver 30. The battery unit 311 stores the power output from the power supply control unit 310, and supplies the stored power to the power receiver 30.

[0027] The external IF unit 312 includes a connector to which a connector such as a USB cable can be connected to connect to the IoT device 31. The external IF unit 312 supplies the power output from the power supply control unit 310 to the IoT device 31.

[0028] The communication unit 308 communicates with the power supply control server 10 and the power transmitter 20 via the communication network NW. The communication unit 308 includes, for example, a communication antenna for communication. The communication unit 308 may communicate using the same frequency band as the band in which any of the power supply antennas included in the power supply antenna unit 300 transmits radio waves, or may communicate using a frequency band different from the band in which any of the power supply antennas transmit radio waves.

[0029] The power supply control unit 309 controls power supply to the IoT device 31. The power supply control unit 309 monitors the remaining battery level of the IoT device 31, and requests the power supply control server 10 to start power supply, etc., depending on the state of the remaining battery level.

[0030] First, a method for the power supply control unit 309 to monitor the remaining battery level will be described. The power supply control unit 309 monitors the remaining battery level in the IoT device 31 periodically or irregularly. For example, the power supply control unit 309 communicates with the IoT device 31 via the external IF unit 312 and requests the IoT device 31 to notify the battery information. The battery information includes information indicating the remaining battery level in the IoT device 31. In response to a request from the power receiver 30, the IoT device 31 outputs the battery information of the IoT device 31 to the power receiver 30 via the external IF unit 312. In this case, for example, an application program for wirelessly supplying power via the power receiver 30 is installed in the IoT device 31 in advance. This application program is executed by a central processing unit (CPU) or the like as hardware of the IoT device 31, so that the IoT device 31 can realize a function of outputting battery information in response to a request from the power supply control unit 309 of the power receiver 30.

[0031] The power supply control unit 309 determines whether or not to supply power to the IoT device 31 based on the battery information acquired from the IoT device 31. When the power supply control unit 309 determines to supply power to the IoT device 31, it selects a power supply mode. The power supply mode is a power supply mode, for example, a high-speed power supply or a low-speed power supply. The high-speed power supply is realized by, for example, supplying power using radio waves for power supply in the 5.7 GHz band. This is because the transmission output in the 5.7 GHz band is set to a higher output value (for example, 32 W) than other frequency bands. The low-speed power supply is realized by, for example, supplying power using radio waves for power supply in the 920 MHz band. This is because the transmission output in the 920 MHz band is set to a lower output value (for example, 1 W) than other frequency bands. In addition to the above, it goes without saying that a power supply mode such as a medium-speed power supply intermediate between the low-speed power supply and the high-speed power supply may be set. The medium-speed power supply is realized, for example, by supplying power using radio waves for power supply in the 2.4 GHz band.

[0032] The power supply control unit 309 determines to supply power when the remaining battery charge of the IoT device 31 is showing a tendency to decrease. For example, the power supply control unit 309 determines to supply power when a combination of the remaining battery charge of the IoT device 31 and its rate of change satisfies a specific power supply condition. In this embodiment, the power supply condition is, for example, information stored in advance in the power supply condition storage unit 313.

[0033] 3 is information showing an example of information stored in the power supply condition storage unit 313 of the embodiment. The power supply conditions include, for example, information corresponding to each item of the power supply mode and the power supply mode selection condition. The power supply modes include, for example, power supply modes M1 to M3, which correspond to high-speed power supply, medium-speed power supply, and low-speed power supply, respectively. The high-speed power supply is power supply using radio waves for power supply in the 5.7 GHz band. The medium-speed power supply is power supply using radio waves for power supply in the 2.4 GHz band. The low-speed power supply is power supply using radio waves for power supply in the 920 MHz band. The power supply mode selection condition includes a condition for selecting a power supply mode. The power supply mode selection condition includes a remaining battery capacity and a rate of decrease in the remaining battery capacity. The remaining battery capacity is the remaining capacity of the battery in the IoT device 31. The rate of decrease in the remaining battery capacity is the rate of decrease in the remaining battery capacity when the remaining battery capacity is decreasing. For example, when the rate of decrease in the remaining battery capacity is 5% / min, this indicates that the remaining battery capacity is decreasing at a rate of 5% per minute.

[0034] For example, in the example of this figure, three patterns of conditions are set as conditions for selecting the power supply mode M1 (high-speed power supply). The first pattern is a condition where the remaining battery capacity is 60% or more and the rate of decrease in the remaining battery capacity is 5% or more per minute. The second pattern is a condition where the remaining battery capacity is 30-60% or more and the rate of decrease in the remaining battery capacity is 3% or more per minute. The third pattern is a condition where the remaining battery capacity is less than 30% and the rate of decrease in the remaining battery capacity is 1% or more per minute.

[0035] In the example shown in this figure, three conditions are set as conditions for selecting the power supply mode M2 ​​(medium-speed power supply). The first pattern is a condition where the remaining battery capacity is 60% or more and the rate of decrease in the remaining battery capacity is 3% or more per minute. The second pattern is a condition where the remaining battery capacity is 30-60% or more and the rate of decrease in the remaining battery capacity is 1% or more per minute. The third pattern is a condition where the remaining battery capacity is less than 30% and the rate of decrease in the remaining battery capacity is 0.5% or more per minute.

[0036] In the example of this figure, two patterns of conditions are set as conditions for selecting the power supply mode M3 (low-speed power supply). The first pattern is a condition where the remaining battery level is 60% or more and the rate of decrease in the remaining battery level is 1% or more per minute. The second pattern is a condition where the remaining battery level is 30-60% or more and the rate of decrease in the remaining battery level is 0.5% or more per minute. Note that in the example of this figure, it is shown that the power supply mode M3 (low-speed power supply) is not applied when the remaining battery level of the IoT device 31 is less than 30%.

[0037] Next, a method in which the power supply control unit 309 requests the power supply control server 10 to start power supply, etc., depending on the remaining battery charge of the IoT device 31 will be described.

[0038] As described above, when the power supply control unit 309 determines to supply power to the IoT device 31 depending on the state of the remaining battery charge in the IoT device 31, the power supply control unit 309 determines in which power supply mode to supply power based on the power supply conditions stored in the power supply condition storage unit 313. In this case, the power supply control unit 309 transmits a notification (power supply start request) requesting the power supply control server 10 to start power supply to the power supply control server 10 via the communication unit 308. The power supply start request includes, for example, information indicating the power supply mode, a device ID capable of identifying the power receiver 30, and battery information of the power receiver 30.

[0039] Furthermore, when the remaining battery charge of the IoT device 31 exceeds a threshold value (e.g., 90%) while wireless power supply is being performed, the power supply control unit 309 determines to end power supply. In this case, the power supply control unit 309 transmits a notification (power supply end request) requesting the power supply control server 10 to end power supply to the power supply control server 10 via the communication unit 308. The power supply end request includes, for example, a device ID capable of identifying the power receiver 30, battery information of the power receiver 30, and the like.

[0040] Here, when wireless power supply is performed in a power supply mode corresponding to low-speed power supply, if high-load signal processing, such as video downloading, is started in the IoT device 31, the amount of power consumed by the signal processing may become larger than the amount of power supplied by wireless power supply. In such a case, it is better to change to a power supply mode corresponding to high-speed power supply to increase the amount of power supplied by wireless power supply and suppress the decrease in the remaining battery power of the IoT device 31. Alternatively, when wireless power supply is being performed in a power supply mode corresponding to high-speed power supply, the amount of power consumption related to signal processing may be reduced due to the end of high-load signal processing that has been performed up until that point, etc. In such a case, it is better to switch to a power supply mode corresponding to low-speed power supply so as to reduce the amount of power supply by wireless power supply. As a countermeasure, in this embodiment, the power supply mode in which wireless power supply is being performed can be changed. Specifically, when the remaining battery charge of the IoT device 31 changes differently from the change in the remaining battery charge expected to be caused by wireless power supply while wireless power supply is being performed, the power supply control unit 309 determines to change the power supply mode. In this case, the power supply control unit 309 transmits a notification (power supply change request) to the power supply control server 10 via the communication unit 308, requesting the power supply control server 10 to change the power supply mode. The power supply change request includes, for example, information indicating the changed power supply mode, a device ID capable of identifying the power receiver 30, and battery information of the power receiver 30.

[0041] In addition, when the power supply mode can be changed, it is preferable that not only when the power supply mode is changed, but also when the power supply mode is not changed, that is, when the power supply mode is maintained, the power supply control server 10 can be informed of this. For example, when the remaining battery level of the IoT device 31 shows a change equivalent to the change in the remaining battery level expected due to wireless power supply while wireless power supply is being performed, it is determined that the power supply mode is to be maintained. In this case, the power supply control unit 309 transmits a notification (power supply maintenance request) to the power supply control server 10 via the communication unit 308, requesting the power supply control server 10 to maintain the power supply mode. The power supply maintenance request includes, for example, information indicating the power supply mode to be maintained, a device ID capable of identifying the power receiver 30, and battery information of the power receiver 30.

[0042] Furthermore, the power supply control unit 309 may control the power supply of the battery unit 311. For example, the power supply control unit 309 controls the power supply of the battery unit 311 in a similar manner to the method of controlling the power supply to the IoT device 31. Specifically, the power supply control unit 309 monitors the remaining battery level of the battery unit 311, and when a predetermined power supply start condition of the battery unit 311 is satisfied, the power supply control unit 310 controls the power supply control unit 310 so that all or a part of the radio waves (electric power) received from the power transmitter 20 is supplied to the battery unit 311. The power supply start condition of the battery unit 311 here is, for example, a condition that the remaining battery level of the battery unit 311 is less than a threshold value (e.g., 60%). In addition, when the remaining battery level of the battery unit 311 satisfies a predetermined power supply end condition of the battery unit 311, for example, a condition that the remaining battery level of the battery unit 311 is equal to or greater than a threshold value (e.g., 90%), the power supply control unit 309 controls the power supply control unit 310 so as not to supply the radio waves received from the power transmitter 20 to the battery unit 311. For example, when the power supply control unit 309 determines to start supplying power to the IoT device 31, it may acquire the remaining battery charge of the battery unit 311 and determine whether or not to supply power to the battery unit 311 based on the acquired remaining battery charge.

[0043] 4 and 5 are sequence diagrams showing the flow of processing performed by the wireless power supply system 1 of the embodiment. Fig. 4 shows the flow of processing performed before starting wireless power supply to the IoT device 31. Fig. 5 shows the flow of processing for changing or maintaining the power supply mode during wireless power supply.

[0044] 4, the power supply control server 10 monitors the power supply status (step S100). Step S100 includes processes shown in steps S10 to S14. Specifically, the power supply control server 10 periodically or irregularly transmits a notification to each of the power transmitters 20 to inquire about the power supply status, etc. (step S10).

[0045] Here, the notification inquiring about the power supply status, etc., is, for example, a notification inquiring about the number of power receivers 30 to which the power transmitter 20 is currently supplying power, the number of power receivers 30 present in the power supply area E of the power transmitter 20, the upper limit number of power receivers 30 to which the power transmitter 20 can supply power, etc. For example, the wireless power supply system 1 may employ a system in which time division multiple access (TDMA) is performed so that one power transmitter 20 can wirelessly supply power to multiple power receivers 30, and the power transmitter 20 transmits radio waves for power supply to different power receivers 30 for each time slot. In this case, the upper limit number of power receivers 30 to which the power transmitter 20 can supply power is determined according to the number of time slots. When a system that supplies power using such TDMA is adopted in the wireless power supply system 1, one power transmitter 20 can wirelessly supply power to multiple power receivers 30, so the number of power receivers 30 to which the power transmitter 20 is currently supplying power and the upper limit number of power receivers 30 to which the power transmitter 20 can supply power are examples of the power supply status.

[0046] Each of the power transmitters 20 receives a notification inquiring about the power supply status, etc., transmitted by the power supply control server 10, and responds to the received notification inquiring about the power supply status, etc. (steps S11 to S13). The power supply control server 10 receives the responses transmitted by each of the power transmitters 20, and updates a power supply management DB (database) according to the received responses (step S14). The power supply management DB is a database for managing power supply by the power transmitters 20. The power supply management DB stores, as the power supply status, for example, the number of power receivers 30 to which the power transmitter 20 is currently supplying power, the number of power receivers 30 present in the power supply area E of the power transmitter 20, the upper limit number of power receivers 30 to which the power transmitter 20 can supply power, and the like. The information stored in the power supply management DB is updated as needed according to changes in the power supply status. The power supply management DB may be provided in the power supply control server 10, or may be provided in a database server or the like that is external to the power supply control server 10 and communicably connected to the power supply control server 10.

[0047] Meanwhile, the IoT device 31 transmits battery information of the IoT device 31 to the power receiver 30 (step S15). The IoT device 31 may output the battery information in response to a request from the power receiver 30, or may output the battery information of the IoT device 31 to the power receiver 30 periodically or irregularly. Communication between the power receiver 30 and the IoT device 31 is performed, for example, via the external IF unit 312, and more specifically, using a communication terminal provided in the USB connector.

[0048] The power receiver 30 receives the battery information of the IoT device 31, and determines whether or not to start power supply to the IoT device 31 based on the received battery information (step S16). The power receiver 30 determines to start power supply when the remaining battery charge of the IoT device 31 and the rate of decrease in the remaining battery charge satisfy the power supply condition stored in the power supply condition storage unit 313.

[0049] When it is determined that power supply to the IoT device 31 should be started, the power receiver 30 makes a power supply start request (step S17). When it is determined in step S16 that power supply should be started, the power receiver 30 first determines in which of the multiple notified power supply modes the power receiver 30 will start power supply based on the power supply conditions. The power receiver 30 transmits a power supply start request to the power supply control server 10, the request including information indicating the power supply mode, a device ID capable of identifying the power receiver 30, and battery information of the power receiver 30. As a result, the power receiver 30 makes a power supply start request.

[0050] In response to the power supply start request, the power supply control server 10 selects the power transmitter 20 that will supply power to the power receiver 30, and notifies the power receiver 30 of the selected power transmitter 20 (step S18). The power supply control server 10 receives the power supply start request, and acquires the power supply mode indicated in the received power supply start request. The power supply control server 10 selects the power transmitter 20 that will supply power to the power receiver 30, based on the acquired power supply mode and the power supply status of the power transmitter 20. For example, the power supply control server 10 selects, from among the power transmitters 20, a power transmitter 20 that satisfies all three conditions as the power transmitter 20 that will supply power to the power receiver 30 that has notified the power supply start request. Of the three conditions, the first condition is that the power transmitter 20 is installed in a power supply area E in which the power receiver 30 is present. The second condition is that the power transmitter 20 is capable of transmitting radio waves in a frequency band corresponding to the power supply mode indicated in the power supply start request. The third condition is that there is a time slot in which radio waves for power supply are not being transmitted. The power supply control server 10 transmits the identification information of the selected power transmitter 20 to the power receiver 30 as a response to the power supply start request.

[0051] The power receiver 30 receives a response to the power supply start request, and sets the power supply antenna based on the received response (step S19). The power supply control unit 309 of the power receiver 30 controls the SW unit 307 to set the power supply antenna corresponding to the desired frequency band among the multiple power supply antennas to be output to the power supply control unit 310.

[0052] The power receiver 30 makes a power transmission request to the power transmitter 20 (step S20). The power transmission request is a notification requesting the power transmitter 20 to transmit power to the power receiver 30. In response to the power supply start request, the power receiver 30 transmits a power transmission request to the power transmitter 20 indicated as the power transmitter 20 that transmits power to the power receiver 30. The power transmission request is transmitted to the power transmitter 20 by, for example, setting the frequency of a periodically transmitted beacon signal or the content of a signal included in a specific signal format to the content corresponding to the power transmission request.

[0053] When the power transmitter 20 receives a transmission request from the power receiver 30, the power transmitter 20 detects the power receiver 30 that transmits radio waves for power supply based on the received transmission request (step S21).

[0054] The power transmitter 20 transmits an authentication request for the power receiver 30 to the power supply control server 10 (step S22). The authentication request is a notification requesting a determination as to whether or not the power receiver 30 is a power receiver that is registered in advance as a target for wireless power supply in the wireless power supply system 1. For example, when the power receiver 30 receives a wireless power feeding service using the wireless power feeding system 1, the power receiver 30 performs user registration in advance. The power receiver 30 performs user registration by notifying the power feeding control server 10 of registration information such as identification information of the power receiver 30, power feeding specifications (such as the maximum power and maximum voltage that the power receiver 30 can receive), and an authentication number (password) for authentication. The power feeding control server 10 registers the registration information obtained from the power receiver 30 during user registration, for example, in a power feeding management DB or the like. The power transmitter 20, for example, requests an authentication number (password) from the power receiver 30 that has notified the power transmission request, and makes an authentication request by transmitting the authentication number (password) notified by the power receiver 30 in response to this request and the identification information of the power receiver 30 to the power supply control server 10.

[0055] In response to the authentication request from the power transmitter 20, the power supply control server 10 executes authentication of the power receiver 30 (step S23). The power supply control server 10 judges whether or not a combination of the authentication number (password) and the identification information indicated in the authentication request is stored in the power supply management DB. When the combination of the authentication number (password) and the identification information indicated in the authentication request is stored in the power supply management DB, the power supply control server 10 judges that the authentication is OK, that is, that the power receiver 30 is a power receiver registered in advance as a target for wireless power supply in the wireless power supply system 1. On the other hand, when the combination of the authentication number (password) and the identification information indicated in the authentication request is not stored in the power supply management DB, the power supply control server 10 judges that the authentication is NG, that is, that the power receiver 30 is not a power receiver registered in advance as a target for wireless power supply in the wireless power supply system 1. The power supply control server 10 transmits the authentication result to the power transmitter 20 (step S24).

[0056] The power transmitter 20 determines whether the authentication result transmitted from the power supply control server 10 indicates that the authentication is OK, that is, whether the power receiver 30 is a power receiver that is registered in advance as a target for wireless power supply in the wireless power supply system 1 (step S25). If the authentication is not OK, that is, if the authentication is NG, the power transmitter 20 ends the process without supplying power.

[0057] If it is determined in step S25 that the authentication is successful, the power transmitter 20 transmits radio waves for power supply to the power receiver 30 (step S26). The power receiver 30 receives the radio waves for power supply transmitted from the power transmitter 20, and supplies the received radio waves (electric power) to the IoT device 31 via the external IF unit 312 (step S27). Thus, power is supplied to the IoT device 31.

[0058] As shown in FIG. 5, during power supply by wireless power supply, the battery status of the IoT device 31 is monitored periodically or irregularly (step S280). The process shown in step S28 is similar to the process shown in step S15. The power receiver 30 transmits power supply information to the power transmitter 20 (step S29). The power supply information is information indicating the battery status of the IoT device 31 during power supply. The power supply information includes battery information transmitted from the IoT device 31 and identification information of the power receiver 30 during charging. The power receiver 30 transmits the power supply information received from the power receiver 30 to the power supply control server 10 (step S30).

[0059] The power receiver 30 receives battery information of the IoT device 31 and determines whether to change the power supply mode based on the received battery information (step S31). When the time series change in the remaining battery charge of the IoT device 31 is different from the time series change in the remaining battery charge expected due to wireless power supply, the power receiver 30 determines to change the power supply mode. On the other hand, when the time series change in the remaining battery charge of the IoT device 31 is equivalent to the time series change in the remaining battery charge expected due to wireless power supply, the power receiver 30 determines not to change the power supply mode, i.e., to maintain the current power supply mode.

[0060] The power receiver 30 executes a series of processes shown in step S320 when maintaining the power supply mode, and executes a series of processes shown in step S360 when changing the power supply mode.

[0061] Step S320 includes the processes shown in steps S32 to S35. When maintaining the power supply mode, the power receiver 30 transmits a power supply maintenance request to the power supply control server 10 (step S32). In response to the power supply maintenance request, the power supply control server 10 transmits a notice (power supply maintenance) to the power transmitter 20 supplying power to the power receiver 30, instructing the power transmitter 20 to maintain the power supply (step S33). In response to the power supply maintenance from the power supply control server 10, the power transmitter 20 transmits radio waves for power supply to the power receiver 30 (step S34). The process shown in step S35 is equivalent to the process shown in step S27.

[0062] Step S360 includes the processes shown in steps S36 to S41. When changing the power supply mode, the power receiver 30 transmits a power supply change request to the power supply control server 10 (step S36). In response to the power supply change request, the power supply control server 10 selects a power transmitter 20 that supplies power to the power receiver 30, and notifies the power receiver 30 of the selected power transmitter 20 (step S37). The process shown in step S37 is equivalent to the process shown in step S18, and therefore a detailed description thereof will be omitted. The power receiver 30 receives the response to the power supply change request, and executes a power transmission establishment process based on the received response (step S38). The power transmission establishment process is equivalent to a series of processes shown in each of steps S19 to S27.

[0063] The power supply control server 10 transmits a notification (power supply end) to the power transmitter 20 (referred to as the old power transmitter) that has been supplying power to the power receiver 30 before the power supply mode was changed, requesting the power transmitter 20 to end power supply (step S38). In response to the power supply end from the power supply control server 10, the power transmitter 20 ends power supply to the power receiver 30. The power supply control server 10 updates the power supply management DB (step S40). The power supply control server 10, for example, executes the power transmission establishment process and determines whether or not power supply by the power transmitter 20 (referred to as a new power transmitter) after changing the power supply mode has started. For example, the power supply control server 10 determines that power supply from the new power transmitter has started when power supply information corresponding to step S30 is received from the new power transmitter. When power supply by the new power transmitter has started, the power supply control server 10 ends power supply to the power receiver 30 by the old power transmitter.

[0064] As described above, the power receiver 30 of the embodiment includes the power supply antenna unit 300, the SW unit 307, the external IF unit 312 (an example of an external interface unit), and the power supply control unit 309. The power supply antenna unit 300 has a plurality of power supply antennas that receive radio waves in a plurality of frequency bands assigned for power supply. The SW unit 307 switches and outputs the power supply radio waves received by any of the power supply antennas included in the power supply antenna unit 300. The external IF unit 312 connects to the IoT device 31 that is the power receiving target. The power supply control unit 309 supplies the radio waves output from the SW unit 307 to the IoT device 31 via the external IF unit 312. As a result, the power receiver 30 of the embodiment can supply power received by the power receiver 30 via wireless power supply to the IoT device 31 connected via the external IF unit 312. Therefore, the existing IoT device can be made compatible with wireless power supply.

[0065] In the power receiver 30 of the embodiment, the multiple frequency bands allocated for power supply include three frequency bands, 920 MHz band, 2.4 GHz band, and 5.7 GHz band. As a result, the power receiver 30 of the embodiment can supply power using power corresponding to each of the three frequency bands, 920 MHz band, 2.4 GHz band, and 5.7 GHz band, allocated as frequencies for wireless power supply.

[0066] In the power receiver 30 of the embodiment, the power supply control unit 309 acquires battery information including the remaining battery charge of the IoT device via the external IF unit 312. Based on the acquired battery information, the power supply control unit 309 determines whether to supply radio waves of any of the multiple frequency bands allocated for power supply to the IoT device 31. The power supply control unit 309 requests the power supply control server 10 to start power supply so that the power transmitter 20 corresponding to the determined frequency band transmits radio waves for power supply. As a result, the power receiver 30 of the embodiment can determine whether to supply high speed power or low speed power depending on the remaining battery charge of the IoT device 31, and therefore can perform more appropriate wireless power supply.

[0067] In the power receiver 30 of the embodiment, the power supply control unit 309 acquires battery information while supplying power to the IoT device 31 via the external IF unit 312. The power supply control unit 309 determines whether or not to change the power supply mode (frequency band of radio waves for power supply) based on the acquired remaining battery level. When the power supply control unit 309 determines to change the frequency band, it requests the power supply control server 10 to change the power supply so that the power transmitter 20 corresponding to the changed frequency transmits radio waves for power supply. In this way, the power receiver 30 of the embodiment can change the power supply mode while wireless power supply is being performed to the IoT device 31. Therefore, in a state where wireless power supply is being performed, the power supply mode can be changed to a more appropriate power supply mode according to a change in the battery status caused by a change in the load of signal processing performed by the IoT device 31, etc.

[0068] Furthermore, in the power receiver 30 of the embodiment, the power supply control unit 309 determines whether or not to change the power supply mode (the frequency band of radio waves for power supply) based on the amount of change in the remaining battery charge of the IoT device 31 relative to the amount of change caused by power supply to the IoT device 31 via the external IF unit 312. As a result, in the power receiver 30 of the embodiment, when the battery status of the IoT device 31 being supplied with power is different from the expected status, for example, when the recovery of the remaining battery charge is slower than expected, it is possible to switch to a power supply mode that can supply power more quickly.

[0069] Moreover, the wireless power supply system 1 of the embodiment includes a power receiver 30 and a power supply control server 10. The power supply control server 10 controls the power transmitter 20 so that radio waves for power supply are transmitted by the power transmitter 20 corresponding to any one of a plurality of frequency bands allocated for power supply in response to a request (power supply start request or power supply change request) from the power receiver 30. In this way, the wireless power supply system 1 of the embodiment can make existing IoT devices compatible with wireless power supply.

[0070] In the above embodiment, the three frequency bands, 920 MHz band, 2.4 GHz band, and 5.7 GHz band, are assigned as frequency bands for power supply, but the present invention is not limited to this. It is expected that the number of frequency bands available for wireless power supply will increase in the future. For example, the 24 GHz band may be newly assigned as a frequency band for power supply. When a frequency band different from the three frequency bands, 920 MHz band, 2.4 GHz band, and 5.7 GHz band (hereinafter referred to as a new allocated band) is allocated as a frequency band for power supply, the power receiver 30 may be configured to receive wireless power transmitted using the new allocated band. Specifically, the power supply antenna unit 300 includes a fourth power supply antenna unit including a power supply antenna that receives radio waves in the new allocated band, and a rectifier circuit for the new allocated band. The fourth power supply antenna unit receives wireless power transmitted using the new allocated band. The rectifier circuit for the new allocated band is provided at a stage subsequent to the fourth power supply antenna unit, and converts the radio waves received by the fourth power supply antenna unit into direct current and outputs the converted power to the SW unit 307. The SW unit 307 outputs the power output from any of the rectifier circuits 302, 304, and 306 and the rectifier circuit for the new allocated band to the power supply control unit 310 under the control of the power supply control unit 309. The power receiver 30 may be configured to be compatible with all four frequency bands allocated for power supply (920 MHz band, 2.4 GHz band, 5.7 GHz band, and the newly allocated band), or may be configured to be compatible with wireless power supply using any two or three of the four frequency bands. Similarly, in the case where three frequency bands (920 MHz band, 2.4 GHz band, and 5.7 GHz band) are allocated for power supply, the power receiver 30 may be configured to be compatible with all three frequency bands allocated for power supply, or may be configured to be compatible with wireless power supply using any two of the three frequency bands.

[0071] The wireless power supply system 1, the power receiver 30, and the power supply control server 10 in the above-described embodiment may be realized in whole or in part by a computer. In that case, a program for realizing the function may be recorded in a computer-readable recording medium, and the program recorded in the recording medium may be read into a computer system and executed to realize the function. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. The term "computer-readable recording medium" refers to a portable medium such as a flexible disk, an optical magnetic disk, a ROM, a CD-ROM, and a storage device such as a hard disk built into a computer system. The term "computer-readable recording medium" may also include a medium that dynamically holds a program for a short period of time, such as a communication line when a program is transmitted via a network such as the Internet or a communication line such as a telephone line, and a medium that holds a program for a certain period of time, such as a volatile memory inside a computer system that is a server or a client in that case. The above-described program may be a program for realizing a part of the above-described function, or may be a program that can realize the above-described function in combination with a program already recorded in the computer system, or may be a program that is realized using a programmable logic device such as an FPGA. [Explanation of symbols]

[0072] 1. Wireless power supply system 10…Power supply control server 20...Transmitter 30…Power receiver 31…IoT equipment 300…Power supply antenna section 301…First power supply antenna section 302, 304, 306... Rectifier circuit 303…Second power supply antenna section 305…Third power supply antenna section 306... Rectifier circuit 307…SW section (switch section) 308…Communications Department 309…Power supply control unit 310...Power supply control unit 311…Battery section 312...External IF section (external interface section)

Claims

1. a power supply antenna unit having a plurality of power supply antennas each receiving radio waves in a plurality of frequency bands assigned for power supply; a switch unit that switches and outputs the power supply radio waves received by any one of the power supply antennas included in the power supply antenna unit; An external interface unit that connects to an IoT device that is a power receiving target; A power supply control unit that supplies the radio waves output from the switch unit to the IoT device via the external interface unit; A receiver equipped with the above.

2. The multiple frequency bands allocated for power supply include three frequency bands: 920 MHz band, 2.4 GHz band, and 5.7 GHz band. The power receiver according to claim 1 .

3. The power supply control unit acquires battery information including a remaining battery charge of the IoT device via the external interface unit, determines whether to supply power to the IoT device using any of a plurality of frequency bands allocated for power supply based on the acquired battery information, and issues a power supply start request to a power supply control server so that a power transmitter corresponding to the determined frequency band transmits radio waves for power supply. The power receiver according to claim 1 .

4. The power supply control unit acquires the battery information while supplying power to the IoT device via the external interface unit, and determines whether or not to change the frequency band of the radio waves for power supply based on the acquired battery information. When it is determined that the frequency band is to be changed, the power supply control unit requests a power supply control server to change the power supply so that the radio waves for power supply are transmitted by a power transmitter corresponding to the changed frequency. The power receiver according to claim 3 .

5. The power supply control unit determines whether or not to change the frequency band of the radio wave for power supply based on a change in the remaining battery charge relative to a change caused by power supply to the IoT device via the external interface unit. The power receiver according to claim 3 .

6. The power receiver according to claim 1 ; a power supply control server that controls a power transmitter so that the power transmitter transmits radio waves for power supply corresponding to any one of a plurality of frequency bands allocated for power supply in response to a request from the power receiver; A wireless power supply system comprising:

7. A wireless power supply method performed by a power receiver including a power supply antenna unit having a plurality of power supply antennas each receiving radio waves of a plurality of frequency bands assigned for power supply, and an external interface unit connected to an IoT device that is a power receiving target, a switch unit that switches and outputs the power supply radio waves received by any one of the power supply antennas included in the power supply antenna unit; A power supply control unit supplies the radio waves output from the switch unit to the IoT device via the external interface unit. Wireless power supply method.

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