送電装置及び送電装置を制御する方法

Abstract

To appropriately transmit power from a power transmitting device to a plurality of power receiving devices. [Solution] A power transmission device 100 that wirelessly transmits power to multiple power receiving devices 200 using a time-division method derives multiple power loss data between the power transmission device 100 and the multiple power receiving devices 200 based on multiple received powers received from the multiple power receiving devices 200, and detects foreign objects within the power transmission range of the power transmission device 100 based on the multiple power loss data.

Description

[Technical Field]

[0001] The present invention relates to wireless power transmission technology. [Background technology]

[0002] In recent years, technological development of wireless power transmission systems has been widespread. Patent Document 1 discloses a power transmitting device and a power receiving device that comply with the standard (WPC standard) established by the Wireless Power Consortium (WPC), a standardization organization for wireless charging standards. Patent Document 2 also discloses a foreign object detection method in the WPC standard. Here, a foreign object refers to a conductive object such as a metal piece. The WPC standard first calculates in advance the power loss between the power transmitting device and the power receiving device when there is no foreign object based on the difference between the transmitted power at the power transmitting device and the received power at the power receiving device, and defines this calculated value as the power loss in the normal state (when there is no foreign object) during power transmission processing. Then, if the power loss calculated between the power transmitting device and the power receiving device during subsequent power transmission deviates by more than a threshold value from the reference power loss in the normal state, it is determined that there is a foreign object or that there is a possibility of a foreign object being present. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-56959 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-70074 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a power transmitting device capable of charging multiple power receiving devices, the power loss between the power transmitting device and a first power receiving device is different from the power loss between the power transmitting device and a second power receiving device, which poses a problem of reduced accuracy in foreign object detection when the same power loss is used as the reference power loss in the normal state. Furthermore, when a first power receiving device and a second power receiving device are placed on the power transmitting device, the power loss between the power transmitting device and the first power receiving device may be affected by the second power receiving device. Similarly, the power loss between the power transmitting device and the second power receiving device may be affected by the first power receiving device. Therefore, if there is a change in the status (number, etc.) of the power receiving devices placed on the power transmitting device, the previously calculated power loss between the power transmitting device and the power receiving device in the normal state also changes, resulting in a problem of reduced accuracy in foreign object detection.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to appropriately transmit power from a power transmitting device to a plurality of power receiving devices. [Means for solving the problem]

[0006] As one means for solving the above problems, a power transmission device of the present invention has the following configuration: A plurality of coils; a transmitting means for wirelessly transmitting a plurality of pings; an acquisition means for acquiring a first packet including identification information of a first power receiving device from a first power receiving device, and acquiring a second packet including identification information of a second power receiving device from a second power receiving device different from the first power receiving device; a determination means for determining that the first power receiving device and the second power receiving device exist based on identification information of the first power receiving device and identification information of the second power receiving device; a selection means for selecting, when the first power receiving device and the second power receiving device are present, coils corresponding to the first power receiving device and the second power receiving device from the plurality of coils; a power transmitting means for wirelessly transmitting power to the first power receiving device via a first coil included in the plurality of coils and corresponding to the first power receiving device, and for wirelessly transmitting power to the second power receiving device via a second coil included in the plurality of coils and corresponding to the second power receiving device, the transmitting means does not transmit a Ping through a coil in the vicinity of the first coil while wirelessly transmitting power to the first power receiving device through the first coil; The acquiring means acquires configuration information of the first power receiving device. [Effects of the Invention]

[0007] This makes it possible to appropriately transmit power from the power transmitting device to a plurality of power receiving devices. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a block diagram illustrating a configuration example of a power transmission device. [Figure 2] FIG. 2 is a block diagram illustrating a configuration example of a power receiving device. [Figure 3] FIG. 2 is a block diagram illustrating an example of a functional configuration of a control unit of the power transmitting device. [Figure 4] 4 is a flowchart of a process executed by the power transmitting device according to the first embodiment. [Figure 5] 10 is a flowchart of a process in a power transfer phase according to the first embodiment. [Figure 6] 10 is a flowchart of a process executed by a power transmitting device according to a second embodiment. [Figure 7] 10 is a flowchart of a process in a power transfer phase according to the second embodiment. [Figure 8] 11 is a flowchart of a process executed by a power transmitting device according to a third embodiment. [Figure 9] 11 is a flowchart of a process in a power transfer phase according to the third embodiment. [Figure 10]10A and 10B are diagrams illustrating a foreign object detection method based on a power loss technique. [Figure 11] 1 shows an example of the configuration of a wireless power transmission system. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0010] [Embodiment 1] <Foreign object detection method based on power loss technique> First, a foreign object detection method based on the power loss technique defined in the WPC (Wireless Power Consortium) standard will be described with reference to FIG. 10. FIG. 10 is a diagram illustrating the foreign object detection method based on the power loss technique. In FIG. 10, the horizontal axis represents the transmitted power of a power transmitting device, and the vertical axis represents the received power of a power receiving device. A foreign object is a conductive object such as a metal piece, and is an object different from the power receiving device. In other words, when multiple power receiving devices are targets for power transmission, the other power receiving devices are considered foreign objects. A power receiving device currently transmitting power or a power receiving device performing communication for power transmission may also be considered a power transmission target.

[0011] First, the power transmitting device transmits power to the power receiving device, and the power transmitting device receives from the power receiving device a received power value Pr1 of the power received by the power receiving device. The power transmitting device then stores the transmitted power value Pt1 at that time (point 1000). Here, the transmitted power value Pt1 or the received power value Pr1 is a predetermined minimum transmitted power or received power. At this time, the power receiving device controls the load so that the received power is minimized. For example, the power receiving device may disconnect the load from the power receiving antenna so that the received power is not supplied to the load (such as a charging circuit or battery). This state may be called a light load state. At this time, the power transmitting device can recognize that the power loss between the power transmitting device and the power receiving device when transmitting Pt1 as the transmitted power is Pt1-Pr1 (Ploss1). Next, the power transmitting device receives from the power receiving device a value Pr2 of the received power received by the power receiving device. At this time, the power receiving device supplies the received power to the load. The power transmitting device then stores the transmission power value Pt2 at that time (point 1001). Here, the transmission power value Pt2 or the reception power value Pr2 is a predetermined maximum transmission power or reception power. At this time, the power receiving device controls the load so that the received power is the maximum power. For example, the power receiving device connects the power receiving antenna to the load so that the received power is supplied to the load. This state may be called a connected load state. At this time, the power transmitting device can recognize that the power loss between the power transmitting device and the power receiving device when transmitting Pt2 as the transmission power is Pt2 - Pr2 (Ploss2). The power transmitting device then linearly interpolates points 1000 and 1001 to create a line 1002. The line 1002 represents the relationship between the transmission power and the reception power when there are no foreign objects around the power transmitting device and the power receiving device. Therefore, the power transmitting device can predict the received power in a state where there is no foreign object from the transmitted power value and line 1002. For example, if the transmitted power value is Pt3, it can be predicted that the received power value will be Pr3 from point 1003 on line 1002 that indicates the transmitted power value Pt3.

[0012] Here, assume that when the power transmitting device transmits power to the power receiving device with a transmission power of Pt3, the power transmitting device receives a received power value Pr3' from the power receiving device. The power transmitting device calculates Pr3-Pr3' (=Ploss_FO) by subtracting the received power value Pr3' actually received from the power receiving device from the received power value Pr3 when the foreign object is not present. This Ploss_FO can be considered to be the power loss consumed by a foreign object if one is present between the power transmitting device and the power receiving device. Therefore, if the power Ploss_FO that would have been consumed by the foreign object is equal to or greater than a predetermined threshold, it is determined that a "foreign object is present" or that a "foreign object may be present."

[0013] Alternatively, the power transmitting device may calculate the power loss Pt3-Pr3 (Ploss3) between the power transmitting device and the power receiving device in advance from the received power value Pr3 when the foreign object is not present. Next, the power loss Pt3-Pr3' (Ploss3') between the power transmitting device and the power receiving device when the foreign object is present may be calculated from the received power value Pr3' received from the power receiving device when the foreign object is present. The power Ploss_FO that would have been consumed by the foreign object may then be calculated by subtracting Ploss3' from Ploss3 (=Ploss_FO).

[0014] As described above, the power Ploss_FO that would have been consumed by a foreign object may be calculated as Pr3 - Pr3' (= Ploss_FO) or as Ploss3' - Ploss3 (= Ploss_FO). In the following description of this specification, the method of calculating Ploss3' - Ploss3 (= Ploss_FO) will be primarily described, but the method of calculating Pr3 - Pr3' (= Ploss_FO) is also applicable. This concludes the explanation of foreign object detection based on the power loss method.

[0015] <Outline of foreign object detection method according to this embodiment> Next, a foreign object detection method in a power transmitting device capable of transmitting power to multiple power receiving devices will be described. Fig. 11 shows an example of the configuration of a wireless power transmission system in this embodiment. Below, the power transmitting device may be referred to as TX and the power receiving device may be referred to as RX. The configurations of TX 100 and RX 200 to 220 are shown in Fig. 1 and Fig. 2, respectively, and will be described in detail later.

[0016] The TX 100 transmits power to the RX 200, 210, and 220 placed on the TX 100 (for example, on a charging stand (placing surface) placed close to the power transmitting antennas 105a, 105b, and 105c) via the power transmitting antennas 105a, 105b, and 105c. The RX 200, 210, and 220 each receive the power transmitted from the TX 100 via the power receiving antenna 205. Note that communication between the TX and each RX is also performed via the power transmitting antenna and the power receiving antenna.

[0017] The TX 100 shown in Fig. 11(a) has power transmitting antennas 105a to 105b, and transmits power to the RX 200 and the RX 210, for example, as shown in Fig. 11(b). The TX 100 shown in Fig. 11(c) has power transmitting antennas 105a to 105c, and transmits power to the RX 200 to 220, for example, as shown in Figs. 11(d) to (f).

[0018] Here, let us consider the power loss between each TX and multiple RXs. In a TX that can transmit (charge) power to multiple RXs (for example, a first RX and a second RX), the power loss between the TX and the first RX differs from the power loss between the TX and the second RX. For example, the TX100 shown in FIG. 11(c) transmits power to the RX200 via the power transmitting antenna 105a and the power receiving antenna 205 that the RX200 has. Furthermore, the TX100 shown in FIG. 11(c) transmits power to the RX210 via the power transmitting antenna 105b and the power receiving antenna 205 that the RX210 has. In this case, the power loss between the TX100 and the RX200 differs from the power loss between the TX100 and the RX210. The reasons for this include the characteristics of the power transmitting antenna, the characteristics of the power receiving antenna, the relative positions of the TX (power transmitting antenna) and RX, the effect that RX 200 has on the electrical characteristics of the power transmitting antenna 105b, the effect that RX 210 has on the electrical characteristics of the power transmitting antenna 105a, the state of the circuit within RX (for example, the connection state of the power receiving antenna and the load (such as a charging circuit or battery)), etc. For this reason, if the same line showing the power loss between TX and RX when no foreign object is present between TX and RX, or the relationship between transmitted power and received power as shown in Figure 10, is used between TX and the first RX and between TX and the second RX, the problem of reduced foreign object detection accuracy arises.

[0019] Furthermore, when a first RX and a second RX are placed on the TX, the power loss between the TX and the first RX may be affected by the second RX. Similarly, the power loss between the TX and the second RX may be affected by the first RX. Therefore, if there is a change in the state of the RXs placed on the TX (number of units, placement position, etc.), the power loss between the TX and RX calculated in advance when there is no foreign object between the TX and RX, or the straight line showing the relationship between transmitted power and received power as shown in Figure 10, will also change, resulting in a problem of reduced foreign object detection accuracy.

[0020] To solve this problem, the TX separately calculates the "power loss between the TX and the first RX when there is no foreign object" and the "power loss between the TX and the second RX when there is no foreign object" as the power loss between the TX and RX when there is no foreign object, calculated in advance. When transmitting power to the first RX, the TX uses the "power loss between the TX and the first RX when there is no foreign object" as a reference, and determines that a "foreign object is present" or that a "foreign object may be present" if the power loss between the TX and the first RX calculated during power transmission deviates from the "power loss between the TX and the first RX when there is no foreign object" by a threshold or more. Similarly, when transmitting power to the second RX, the TX uses the "power loss between the TX and the second RX when there is no foreign object" as a reference, and determines that a "foreign object is present" or that a "foreign object may be present" if the power loss between the TX and the second RX calculated during power transmission processing deviates from the "power loss between the TX and the second RX when there is no foreign object" by a threshold or more.

[0021] In this way, the TX calculates the power loss for each RX in advance when there is no foreign object, and then calculates the power loss for each RX during power transmission, compares them, and determines whether there is a foreign object. This makes it possible to properly detect foreign objects even in a wireless power transfer system in which the TX transmits power to multiple RXs.

[0022] As described above with reference to FIG. 10, the TX can also determine the presence of a foreign object by subtracting the received power value Pr3' actually received from the RX from the received power value Pr3 in a state where no foreign object is present, to calculate Pr3-Pr3' (=Ploss_FO), and determining whether or not the calculated value is equal to or greater than a predetermined threshold. That is, the TX acquires in advance, in a state where no foreign object is present, the "received power value from the first RX in a state where no foreign object is present" and the "received power value from the second RX in a state where no foreign object is present" separately. Then, when transmitting power to the first TX, the TX determines that "a foreign object is present" or "there is a possibility that a foreign object is present" if the difference between the "received power value from the first RX in a state where no foreign object is present" and the received power value from the RX acquired during power transmission is equal to or greater than a threshold. Similarly, when transmitting power to the second RX, the TX determines that "a foreign object is present" or "there is a possibility that a foreign object is present" if the difference between the "received power value from the second RX in a state where no foreign object is present" and the received power value from the RX acquired during power transmission is equal to or greater than a threshold. By determining the presence or absence of a foreign object in this way, it becomes possible to appropriately detect a foreign object even in a wireless power transmission system in which a TX transmits power to multiple RXs.

[0023] Furthermore, the power transmission and reception state must be the same when the power loss between TX and RX is calculated in advance (or when the received power value is received from RX) in a state where there is no foreign object, and when the power loss between TX and RX is calculated during power transmission (or when the received power value is received from RX). The power transmission and reception state includes, for example, the characteristics of the power transmitting antenna, the characteristics of the power receiving antenna, the positional relationship between TX (power transmitting antenna) and RX, the influence that RX200 has on the electrical characteristics of the power transmitting antenna 105b, the influence that RX210 has on the electrical characteristics of the power transmitting antenna 105a, and the state of the circuit within RX (for example, the connection state between the power receiving antenna and the load (such as a charging circuit or battery)).

[0024] To achieve this, for example, when calculating the power loss between TX and RX in advance when no foreign object is present (or when receiving a received power value from RX), the TX first selects one RX (target RX) from multiple RXs to be the target. The TX controls the non-target RXs so that the power transmitted from the TX is not charged or supplied to them. A state in which the transmitted power is not charged or supplied refers, for example, to a state in which the connection to the load (such as a charging circuit or battery) is cut off. The TX then calculates the power loss between TX and the target RX using a power transmitting antenna capable of transmitting power to the target RX. When calculating the power loss between TX and RX during power transmission (or when receiving a received power value from RX), the TX also calculates the power loss between TX and the target RX in a similar state using a power transmitting antenna capable of transmitting power to the target RX. After that, the TX compares the power loss between TX and the target RX calculated during power transmission with the power loss between TX and the target RX calculated in advance when no foreign object is present, and determines whether a foreign object is present between the TX and the target RX. Alternatively, the TX determines whether or not there is a foreign object between the TX and the target RX from the difference between the received power value of the target RX received during power transmission and the received power value of the target RX in a state where there is no foreign object.

[0025] In this way, by matching the state when the power loss between TX and RX is calculated in advance when there is no foreign object with the power transmission and reception state when the power loss between TX and RX is calculated during power transmission (such as the characteristics of the power transmitting antenna, as described above), it becomes possible to properly detect foreign objects even in a wireless power transfer system in which TX transmits power to multiple RX. Furthermore, when TX detects a change in the power transmission and reception state, it redoes the calculation of the "power loss between TX and RX" described above.

[0026] By doing so, it is possible to make the power transmission and reception conditions (such as the characteristics of the power transmitting antenna, the characteristics of the power receiving antenna, the positional relationship between the TX (power transmitting antenna) and the RX, the influence of the RX 200 on the electrical characteristics of the power transmitting antenna 105b, the influence of the RX 210 on the electrical characteristics of the power transmitting antenna 105a, and the state of the circuits within the RX (for example, the connection state of the power receiving antenna and the load (such as a charging circuit or battery))) the same when calculating the power loss between the TX and the RX in advance in a state where there is no foreign object and when calculating the power loss between the TX and the RX during power transmission. Therefore, it is possible to perform appropriate foreign object detection in a wireless power transmission system in which the TX transmits power to multiple RXs.

[0027] [System Configuration] The wireless power transmission system according to this embodiment shown in FIG. 11 will be described in more detail. The TX100 and the RX200, 210, and 220 comply with the WPC standard. The RX200, 210, and 220 receive power from the TX100 and charge their batteries. The TX100 is an electronic device that wirelessly transmits power to the RX200, 210, and 220 placed on the TX100. The following description will be given using an example in which the RX200, 210, and 220 are placed on the TX100. However, when the TX100 transmits power to the RX200, 210, and 220, the RX200, 210, and 220 do not have to be placed on the TX100 as long as they are within the power transmission range of the TX100.

[0028] The RX200, 210, 220, and TX100 may also have a function for executing applications other than wireless charging. An example of the RX200, 210, and 220 is a smartphone, and an example of the TX100 is an accessory device for charging the smartphone. The RX200, 210, 220, and TX100 may be a tablet, a storage device such as a hard disk drive or a memory device, or an information processing device such as a personal computer (PC). The RX200, 210, 220, and TX100 may be, for example, an image input device such as an imaging device (camera, video camera, etc.) or a scanner, or an image output device such as a printer, copier, or projector. The TX100 may also be a smartphone. In this case, the RX200, 210, and 220 may be another smartphone or wireless earphones. The TX100 may also be a charger installed in a console or the like inside a vehicle.

[0029] This system performs wireless power transmission using an electromagnetic induction method for contactless charging based on the WPC standard. That is, the RX200, 210, 220 and the TX100 perform wireless power transmission for contactless charging based on the WPC standard between the power receiving antenna 205 of the RX200, 210, 220 and the power transmitting antennas (power transmitting coils) 105a to 105c of the TX100. Note that the wireless power transmission method (contactless power transmission method) applied to this system is not limited to the method specified by the WPC standard, and may be other methods such as electromagnetic induction, magnetic field resonance, electric field resonance, microwave, or laser. Furthermore, in this embodiment, wireless power transmission is used for contactless charging, but wireless power transmission may also be performed for purposes other than contactless charging.

[0030] Here, power transmission control according to the WPC standard will be described using an example in which the TX100 is the TX and the RX200, 210, and 220 are the RXs. In the WPC standard, the amount of power guaranteed when the RX200, 210, and 220 receive power from the TX100 is specified by a value called Guaranteed Power (hereinafter referred to as "GP"). GP indicates the power value that is guaranteed to be output to the load (e.g., charging circuit, battery, etc.) of the RX200, 210, and 220, even if the positional relationship between the RX200, 210, and 220 and the TX100 changes and the power transmission efficiency between the receiving antenna and the transmitting antenna decreases. For example, if the GP is 5 watts, the TX100 controls power transmission so that it can output 5 watts to the load in the RX200, 210, and 220, even if the positional relationship between the receiving antenna and the transmitting antenna changes and the power transmission efficiency decreases.

[0031] The WPC standard also specifies a method for the TX100 to detect the presence of an object (foreign object) other than the RX unit around the TX100 (near the receiving antenna). More specifically, it specifies a power loss method that detects foreign objects by measuring the difference between the transmitted power of the TX100 and the received power of the RX200, 210, and 220, and a Q-factor measurement method that detects foreign objects by measuring changes in the quality factor (Q-factor) of the transmitting antenna (transmitting coil) of the TX100. Foreign object detection using the power loss method is performed during power transmission (power transmission) (the power transfer phase, described below). Foreign object detection using the Q-factor measurement method is performed before power transmission (the negotiation or renegotiation phase, described below).

[0032] The RX200, 210, 220 and TX100 according to this embodiment communicate for power transmission and reception control based on the WPC standard. The WPC standard defines multiple phases, including a power transfer phase in which power transmission is performed and one or more phases before the actual power transmission, and communication for the necessary power transmission and reception control is performed in each phase. Phases before power transmission may include a selection phase, a ping phase, an identification and configuration phase, a negotiation phase, and a calibration phase. Note that the identification and configuration phase will be referred to as the I&C phase below.

[0033] In the Selection phase, the TX100 transmits Analog Pings intermittently to detect that an object has been placed on the TX100 (for example, that the RX200, 210, 220 or a piece of conductor has been placed on the charging stand of the TX100). The TX100 detects at least one of the voltage and current values ​​of the power transmitting antenna when the Analog Ping is transmitted, and if the voltage value is below a certain threshold or the current value exceeds a certain threshold, it determines that an object is present and transitions to the Ping phase.

[0034] In the Ping phase, the TX100 transmits a Digital Ping with greater power than the Analog Ping. The power of the Digital Ping is sufficient to activate the control units 201 (Fig. 2) of the RX200, 210, and 220 placed on the TX100. The RX200, 210, and 220 notify the TX100 of the magnitude of the received voltage. In this way, the TX100 recognizes that the object detected in the Selection phase is the RX200, 210, or 220 by receiving a response from the RX200, 210, or 220 that received the Digital Ping. When the TX100 is notified of the received voltage value, it transitions to the I&C phase.

[0035] In the I&C phase, the TX100 identifies the RX200, 210, and 220 and acquires device configuration information (capability information) from the RX200, 210, and 220. To do this, the RX200, 210, and 220 transmit an ID packet and a configuration packet to the TX100. The ID packet contains the identification information of the RX200, 210, and 220, and the configuration packet contains the device configuration information (capability information) of the RX200, 210, and 220. Upon receiving the ID packet and configuration packet, the TX100 responds with an acknowledgement (ACK, positive response). Then the I&C phase ends.

[0036] In the Negotiation phase, the GP value is determined based on the GP value requested by the RX200, 210, and 220, the power transmission capability of the TX100, and other factors. The TX100 also performs foreign object detection processing using the Q-factor measurement method in accordance with requests from the RX200, 210, and 220. The WPC standard also specifies a method in which, after transitioning to the Power Transfer phase, processing similar to that of the Negotiation phase is performed again at the request of the RX. The phase in which these processing steps are performed after transitioning from the Power Transfer phase is called the Renegotiation phase.

[0037] In the calibration phase, the RX200, 210, and 220 notify the TX100 of a predetermined received power value (received power value under light load / received power value under maximum load) based on the WPC standard, and the TX100 performs adjustments to transmit power efficiently. The received power value notified to the TX100 can be used for foreign object detection processing using the power loss method.

[0038] In the Power Transfer phase, control is performed to start and continue power transmission, and to stop power transmission due to an error or full charge. To control power transmission and reception, the TX100 and RX200, 210, and 220 use the same power transmitting antenna (power transmitting coil) and power receiving antenna (power receiving coil) as those used when transmitting wireless power based on the WPC standard, and communicate by superimposing a signal on the electromagnetic waves transmitted from the power transmitting antenna or power receiving antenna. The range in which communication based on the WPC standard is possible between the TX100 and RX200, 210, and 220 is approximately the same as the power transmission range of the TX100.

[0039] [Configuration of power transmission device and power receiving device] Next, the configurations of a power transmitting device and a power receiving device according to this embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a block diagram showing an example of the configuration of a TX (power transmitting device) 100 according to this embodiment. FIG. 2 is a block diagram showing an example of the configuration of an RX (power receiving device) 200 according to this embodiment. Note that the RX 210 and the RX 220 have the same configuration as the RX 200. Note that the configuration described below is merely an example, and part (or in some cases the entirety) of the described configuration may be replaced with another configuration that performs a similar function or may be omitted, or additional configuration may be added to the described configuration. Furthermore, one block described below may be divided into multiple blocks, or multiple blocks may be integrated into one block. Furthermore, although the functions of each functional block described below are implemented as a software program, some or all of the components included in this functional block may be implemented in hardware.

[0040] First, the TX 100 (Fig. 1) will be described. As shown in Fig. 1, the TX 100 has a control unit 101, a power supply unit 102, a power transmission unit 103, a communication unit 104, power transmission antennas 105a to 105c, a memory 106, and an antenna switching unit 107. In Fig. 1, the control unit 101, the power supply unit 102, the power transmission unit 103, the communication unit 104, the memory 106, and the antenna switching unit 107 are depicted as separate entities, but any two or more of these functional blocks may be implemented on the same chip.

[0041] The control unit 101 controls the entire TX 100 by executing a control program stored in the memory 106, for example. The control unit 101 also controls power transmission control, including communication for device authentication in the TX 100. The control unit 101 may also control the execution of applications other than wireless power transmission. The control unit 101 includes one or more processors, such as a CPU (Central Processing Unit) or an MPU (Microprocessor Unit). The control unit 101 may also be configured with dedicated hardware for specific processing, such as an application-specific integrated circuit (ASIC). The control unit 101 may also be configured with an array circuit, such as an FPGA (Field Programmable Gate Array) compiled to execute a specific process. The control unit 101 stores information to be stored during the execution of various processes in the memory 106. The control unit 101 may also measure time using a timer (not shown).

[0042] The power supply unit 102 supplies power to each functional block. The power supply unit 102 is, for example, a commercial power supply or a battery. The battery stores power supplied from the commercial power supply.

[0043] The power transmitting unit 103 converts DC or AC power input from the power supply unit 102 into AC frequency power in a frequency band used for wireless power transmission, and inputs the AC frequency power to the power transmitting antennas 105a to 105c to generate electromagnetic waves for receiving power at the RX. For example, the power transmitting unit 103 converts the DC voltage supplied by the power supply unit 102 into an AC voltage using a switching circuit with a half-bridge or full-bridge configuration using FETs (Field Effect Transistors). In this case, the power transmitting unit 103 includes a gate driver that controls the ON / OFF of the FETs.

[0044] Under the control of the control unit 101, the power transmitting unit 103 adjusts the voltage (power transmission voltage) or current (power transmission current), or both, input to the power transmitting antennas 105a to 105c, thereby controlling the intensity of the electromagnetic waves to be output. Increasing the power transmission voltage or power transmission current increases the intensity of the electromagnetic waves, while decreasing the power transmission voltage or power transmission current decreases the intensity of the electromagnetic waves. Based on instructions from the control unit 101, the power transmitting unit 103 controls the output of AC frequency power so as to start or stop power transmission from the power transmitting antennas 105a to 105c. The power transmitting unit 103 is also assumed to be capable of supplying 15 watts (W) of power to a charging unit of the RX (charging unit 206 (FIG. 2) in the case of the RX200 to 220) that complies with the WPC standard.

[0045] The communication unit 104, under the control of the control unit 101, performs communication with the RX for power transmission control based on the WPC standard as described above. The communication unit 104 modulates electromagnetic waves output from the power transmitting antennas 105a to 105c and transmits information to the RX to perform communication. The communication unit 104 also acquires information transmitted by the RX by demodulating the electromagnetic waves output from the power transmitting antennas 105a to 105c and modulated by the RX. That is, the communication performed by the communication unit 104 is performed by superimposing a signal on the electromagnetic waves transmitted from the power transmitting antennas 105a to 105c. The communication unit 104 may also communicate with the RX using antennas other than the power transmitting antennas 105a to 105c according to a standard other than the WPC standard, or may selectively use multiple communication methods to communicate with the RX.

[0046] The memory 106 can store the control program as well as the status of the TX 100 and RX (received power value, etc.). For example, the status of the TX 100 is acquired by the control unit 101, and the status of the RX is acquired by the RX control unit (in the case of the RX 200 to 220, the control unit 201 (FIG. 2)), and can be received via the communication unit 104.

[0047] A plurality of power transmitting antennas (coils) 105a to 105c are connected to the antenna switching unit 107. The antenna switching unit 107 selects and switches one or more of the plurality of antennas (coils). Although three power transmitting antennas 105a to 105c are shown in FIG. 1, the number of power transmitting coils is not limited to this number. In the following description, the power transmitting antennas 105a to 105c may be collectively referred to as power transmitting antenna 105.

[0048] Next, the RX200 (FIG. 2) will be described. As described above, the RX210 and RX220 have the same configuration as the RX200. As shown in FIG. 2, the RX200 has a control unit 201, a UI (user interface) unit 202, a power receiving unit 203, a communication unit 204, a power receiving antenna 205, a charging unit 206, a battery 207, a memory 208, and a switch unit 209. Note that the multiple functional blocks shown in FIG. 2 may be implemented as a single hardware module.

[0049] The control unit 201 controls the entire RX200 by executing a control program stored in the memory 208, for example. That is, the control unit 201 controls each functional unit shown in FIG. 2. Furthermore, the control unit 201 may perform control for executing applications other than wireless power transmission. An example of the control unit 201 is configured to include one or more processors such as a CPU or an MPU. Note that the control unit 201 may control the entire RX200 (or the entire smartphone if the RX200 is a smartphone) in cooperation with an OS (Operating System) being executed.

[0050] The control unit 201 may also be configured with hardware dedicated to a specific process, such as an ASIC. The control unit 201 may also be configured to include an array circuit, such as an FPGA, compiled to execute a predetermined process. The control unit 201 stores information to be stored while executing various processes in the memory 208. The control unit 201 may also measure time using a timer (not shown).

[0051] The UI unit 202 performs various outputs to the user. The various outputs referred to here include screen display, LED blinking and color changes, audio output from a speaker, vibration of the RX200 main unit, etc. The UI unit 202 is realized by an LCD panel, speaker, vibration motor, etc.

[0052] The power receiving unit 203 acquires, at the power receiving antenna 205, AC power (AC voltage and AC current) generated by electromagnetic induction caused by electromagnetic waves radiated from the power transmitting antenna 105 of the TX100. The power receiving unit 203 then converts the AC power into DC or AC power of a predetermined frequency and outputs the power to the charging unit 206, which performs processing to charge the battery 207. That is, the power receiving unit 203 supplies power to the load in the RX200. The above-mentioned GP is the amount of power guaranteed to be output from the power receiving unit 203. The power receiving unit 203 supplies power for the charging unit 206 to charge the battery 207 and has the capacity to supply 15 watts of power to the charging unit 206. The switch unit 209 controls whether the received power is supplied to the battery (load). When the switch unit 209 connects the charging unit 206 and the battery 207, the received power is supplied to the battery 207. When the switch unit 209 disconnects the charging unit 206 from the battery 207, the received power is not supplied to the battery 207. Although the switch unit 209 is disposed between the charging unit 206 and the battery 207 in FIG. 2 , it may be disposed between the power receiving unit 203 and the charging unit 206. Alternatively, although the switch unit 209 is illustrated as a single block in FIG. 2 , the switch unit may be realized as part of the charging unit 206. The communication unit 204 communicates with the communication unit 104 of the TX100 for power reception control based on the WPC standard as described above. The communication unit 204 demodulates the electromagnetic waves input from the power receiving antenna 205 to acquire information transmitted from the TX100. The communication unit 204 then performs load modulation on the input electromagnetic waves to superimpose a signal related to information to be transmitted to the TX100 onto the electromagnetic waves, thereby communicating with the TX100. The communication unit 204 may communicate with the TX100 using an antenna different from the power receiving antenna 205 and a standard different from the WPC standard, or may selectively use multiple communication methods to communicate with the TX100.

[0053] The memory 208 stores the control program and also stores the status of the TX100 and RX200. For example, the status of the RX200 is acquired by the control unit 201, and the status of the TX100 is acquired by the control unit 101 of the TX100 and can be received via the communication unit 204.

[0054] [Functional configuration of the power transmission device control unit] Next, the functional configuration of the control unit 101 of the TX (power transmitting device) 100 according to this embodiment will be described with reference to Fig. 3. Fig. 3 is a block diagram showing an example of the functional configuration of the control unit 101. The control unit 101 has a communication control unit 301, a power transmission control unit 302, a foreign object detection unit 303, and a calculation unit 304.

[0055] The communication control unit 301 is a processing unit that performs control communication with the RX based on the WPC standard via the communication unit 104. The power transmission control unit 302 is a processing unit that controls the power transmission unit 103 and controls power transmission to the RX. The foreign object detection unit 303 is a processing unit that detects foreign objects by measuring the transmission power of the power transmission unit 103 and the Q value of the power transmission antenna 105. The foreign object detection unit 303 can realize a foreign object detection function using a power loss method and a foreign object detection function using a Q value measurement method. The foreign object detection unit 303 may also perform foreign object detection processing using other methods. For example, in a TX equipped with an NFC (Near Field Communication) communication function, the foreign object detection unit 303 may perform foreign object detection processing using an opposing device detection function based on the NFC standard. In addition to detecting foreign objects, the foreign object detection unit 303 can also detect changes in the state of the TX 100. For example, it is possible to detect an increase or decrease in the number of RXs on the TX 100. The calculation unit 304 measures the power output to the RX via the power transmission unit 103 and calculates the average output power value per unit time. The foreign object detection unit 303 performs foreign object detection processing using a power loss method based on the calculation result by the calculation unit 304 and received power information received from the RX via the communication control unit 301.

[0056] The functions of the communication control unit 301, the power transmission control unit 302, the foreign object detection unit 303, and the calculation unit 304 are realized as programs that run in the control unit 101. Each processing unit is configured as an independent program, and can run in parallel while maintaining synchronization between the programs through event processing or the like.

[0057] [Processing flow by power transmission device] Next, the flow of processing executed by the TX100 will be explained. Figure 4 shows a flowchart of processing executed by the TX100 in this embodiment. This processing can be realized, for example, by the control unit 101 of the TX100 executing a program read from the memory 106. Note that at least part of the following procedure may be realized by hardware. In this case, the hardware can be realized, for example, by using a predetermined compiler to automatically generate a dedicated circuit using a gate array circuit such as an FPGA from a program for implementing each processing step.

[0058] This process starts when the TX100 is started (S401). Alternatively, this process can start when the user of the TX100 inputs an instruction to start a contactless charging application via an input unit (not shown), or when the TX100 is connected to a commercial power source and receives power. This process may also be started by some other trigger. When this process starts, the antenna switching unit 107 of the TX100 selects one power transmitting antenna from multiple power transmitting antennas (power transmitting coils) under the control of the control unit 101 (S402). Next, the TX100 transitions to the selection phase, and the communication control unit 301 transmits an analog ping (S403) and determines whether an object has been detected (S404). If no object is detected, the communication control unit 301 continues to transmit analog pings periodically. If an object is detected in S404 (Yes in S404), the TX 100 transitions to the Ping phase, and the communication control unit 301 transmits a Digital Ping (S405). Then, the foreign object detection unit 303 recognizes that the detected object is an RX. Next, the TX 100 transitions to the Identification & Configuration phase, and the communication control unit 301 acquires RX information (device configuration information (capability information) and RX identification information) from the RX (S406). Next, in S407, the control unit 101 stores in the memory 106 information that associates the RX information acquired in S406 with the power transmitting antenna that detected the RX.

[0059] Next, in S408, the control unit 101 determines whether the selection and switching of all power transmitting antennas has been completed. If the switching of all antennas has not been completed, the process proceeds to S402, where the control unit 101 controls the antenna switching unit 107 to select another power transmitting antenna. If the selection and switching of all power transmitting antennas has been determined to be completed in S408, the process proceeds to S409.

[0060] By performing the processes from S401 to S408, the TX100 can associate each power transmitting antenna (power transmitting coil) of the TX100 with the RX that each power transmitting antenna can recognize. Also, the TX100 can recognize information on all RXs present on the TX100.

[0061] Next, in S409, the control unit 101 determines whether or not there are multiple RXs placed on the TX 100 based on the results of S401 to S408. If it is determined in S409 that there are multiple RXs placed on the TX 100 (Yes in S409), the process proceeds to S410, and if it is determined that there is only one RX placed on the TX 100 (No in S409), the process proceeds to S413. In S410, the control unit 101 selects one RX from the multiple RXs. Hereinafter, in the description of FIG. 4, the one RX selected in S410 will be referred to as the target RX. Then, in S411, the communication control unit 301 transmits a message to RXs other than the target RX (non-target RXs) to notify them that they have not been selected.

[0062] This message may be a message for notifying all RXs of information about the target RX (selected RX), or a message for notifying all RXs of information about non-target RXs (not selected RXs). Since these messages need to be notified to all multiple RXs on the TX 100, they are transmitted from all multiple power transmitting antennas 105 of the TX 100. Alternatively, the non-target RXs may be addressed to notify information indicating that they have not been selected. This message is transmitted from a power transmitting antenna 105 that can communicate with at least the non-target RXs. Alternatively, the target RXs may be addressed to notify information indicating that they have been selected. In this case, the non-target RXs recognize that they have not been selected when they do not receive a message notifying information indicating that they have been selected within a predetermined period of time. Furthermore, this message is transmitted from a power transmitting coil that can communicate with at least the target RX.

[0063] When the non-target RX receives the message, it controls the TX 100 so that it is not charged or supplied with power (for example, it disconnects the connection to the load (charging circuit, battery, etc.)). That is, the RX controls the switch unit 209 (FIG. 2) to disconnect the load (charging circuit, battery, etc.) and does not supply the received power to the load (charging circuit, battery, etc.).

[0064] Next, in S412, the control unit 101 of the TX100 selects a power transmitting antenna (power transmitting coil) that can transmit power to the target RX (corresponding to the target RX) and sets the antenna in a state where communication and power transmission to the target RX are possible. Next, the TX100 transitions to the negotiation phase (S413) and then to the calibration phase (S414). In the calibration phase, the target RX notifies the TX100 of a predetermined received power value (received power value in a light load state / received power value in a maximum load state) based on the WPC standard, and the TX100 makes adjustments to transmit power efficiently. The received power value notified to the TX100 can be used for foreign object detection processing using the power loss method.

[0065] In the calibration phase, the TX 100 derives the relationship between the transmitted power and the received power in a state where no foreign object is present, as described above with reference to FIG. 10 . Specifically, the foreign object detection unit 303 of the TX 100 derives data indicating the power loss between the TX and RX in a state where no foreign object is present (power loss data) based on predetermined received power values ​​(including the received power value in a light load state / light load state and the received power value in a maximum load state / connected load state) acquired from the RX in accordance with the WPC standard (corresponding to the line 1002 in FIG. 10 ). Hereinafter, this power loss data will be referred to as calibration data. This calibration data can be used for foreign object detection processing using the power loss method. Foreign object detection based on the power loss method has been described above. That is, if the power loss between the TX and RX during power transmission, calculated based on the calibration data and the received power value in the RX received during power transmission, is equal to or greater than a predetermined threshold, the TX determines that a foreign object is present or that a foreign object may be present.

[0066] In S415, the control unit 101 associates the calibration data acquired in the calibration phase with the information about the target RX (S407) and saves them in the memory 106. Then, in S416, the control unit 101 determines whether or not it has acquired the calibration data for all RXs placed on the TX 100. This can be determined by checking whether or not the information about the RXs and the calibration data acquired in S415 all correspond to each other, since the TX 100 has acquired the information about all RXs on the TX 100 in S401 to S408.

[0067] Through the above processing from S409 to S416, the TX 100 can individually acquire (derive) calibration data for each RX in a time-division manner for all RXs placed on the TX 100. Next, in S417, the TX 100 transitions to the power transfer phase. Then, the processing ends in S418.

[0068] In the power transfer phase (S417), the TX100 controls the multiple RXs placed on the TX100 to transmit power in a time-division manner. Detailed operations in the power transfer phase will be described below with reference to FIG. 5. FIG. 5 is a flowchart of the processing in the power transfer phase in this embodiment. In the time-division manner, different power transmission periods are assigned to the multiple power receiving devices, and power is transmitted to one power receiving device within the assigned power transmission period.

[0069] When the TX 100 starts the power transfer phase (S501), the control unit 101 selects one RX to be the power transmission target from among multiple RXs mounted on the TX 100 (S502). In the following description of FIG. 5, the one RX selected in S502 will be referred to as the target RX. Then, in S503, the communication control unit 301 transmits a message to RXs other than the target RX (non-target RXs) to notify them that they have not been selected. This message is similar to the message used in the notification of S411 in FIG. 4, and therefore a description thereof will be omitted.

[0070] When the non-target RX receives the message, it controls the TX100 so that it is not charged or supplied with power (for example, it disconnects the connection to the load (such as the charging circuit and battery)). That is, the non-target RX controls the switch unit 209 (FIG. 2) to disconnect the load (such as the charging circuit and battery) and does not supply the received power to the load (such as the charging circuit and battery). Next, in S504, the control unit 101 of the TX100 selects a power transmitting antenna (power transmitting coil) that can transmit power to the target RX (corresponding to the target RX), and sets the antenna to a state where communication and power transmission to the target RX are possible. Next, in S505, the power transmission control unit 302 transmits power to the target RX.

[0071] During power transmission, the foreign object detection unit 303 detects changes in the power transmission and reception state within the power transmission range of the TX 100 (for example, a change in the state on the TX 100) (S506). For example, the foreign object detection unit 303 uses the calibration data of the target RX acquired in the calibration phase (S414 in FIG. 4) to detect a foreign object using the power loss method described above. If a foreign object is detected (Yes in S506), the process returns to S402 in FIG. 4 (processing after TX startup). On the other hand, it is also possible that the change in the power transmission and reception state is not due to a foreign object, but rather to an increase or decrease in the number of RXs placed on the TX 100. Because an increase or decrease in the number of RXs on the TX 100 also causes a change in the power loss described above, the foreign object detection unit 303 can detect an increase or decrease in the number of RXs on the TX 100 using the power loss method.

[0072] If a change in the power transmission and reception state is detected in S506, the process returns to the step after the TX is started in the processing flow of Figure 4, so that power can be transmitted appropriately to all RXs, even if, for example, the number of RXs placed on the TX 100 increases or decreases. While the power transmission control unit 302 is transmitting power, the foreign object detection unit 303 of the TX 100 periodically monitors changes in the power transmission and reception state until power transmission ends (No in S506, No in S507). If the TX 100 ends power transmission without detecting a change in the power transmission and reception state (Yes in S507), it saves information about the target RX (RX for which power transmission has been completed) in the memory 106. Then, the process proceeds to S508, where the control unit 101 compares the information about the RXs that has already been saved and determines whether power transmission to all RXs has been completed. If power transmission to all RXs has been completed, the process ends in S509. If power transmission to all RXs has not been completed, the process returns to S502 (after the Power Transfer phase starts). The completion of power transmission can be confirmed by the communication control unit 301 of the TX 100 receiving an End Power Transfer of the WPC standard from the RX to which power is to be transmitted (the same applies to the following explanation).

[0073] By performing the above-described processes from S501 to S509, the TX 100 can transmit power to a plurality of RXs placed on the TX 100 in a time-division manner, thereby making it possible to properly complete power transmission to all RXs.

[0074] As described above, in this embodiment, the TX100 first sets a specific RX among the multiple RXs placed on the TX100 as the target RX, controls the RXs other than the target RX so that they are not charged or supplied with power from the TX100, and then derives (acquires) calibration data for the target RX (FIG. 4). The TX100 then acquires calibration data for all RXs. Thereafter, in the power transfer phase, the TX100 sets a specific RX among the multiple RXs placed on the TX100 as the target RX, controls the RXs other than the target RX so that they are not charged or supplied with power from the TX100, and then transmits power to the target RX using the calibration data that has already been derived (FIG. 5). This allows the state of each RX when the calibration data is derived to match the state of each RX at the time of power transmission, making it possible for the TX100 to properly complete power transmission to all RXs.

[0075] [Embodiment 2] In the first embodiment, a control method for appropriately transmitting power to a plurality of RXs has been described. In this embodiment, another control method for appropriately transmitting power to a plurality of RXs will be described. Below, differences from the first embodiment will be described, and a description of common parts will be omitted.

[0076] [Processing flow by power transmission device] 6 shows a flowchart of the processing executed by the TX100 in this embodiment. This processing can be realized, for example, by the control unit 101 of the TX100 executing a program read from the memory 106. Note that at least part of the following procedure may be realized by hardware. In this case, the hardware can be realized, for example, by using a predetermined compiler to automatically generate a dedicated circuit using a gate array circuit such as an FPGA from a program for implementing each processing step.

[0077] The processes of S601 to S606 are the same as S401 to S406 in FIG. 4 described in the first embodiment, and therefore description thereof will be omitted. In S607, the control unit 101 selects one RX. This RX may be the RX detected using the power transmitting antenna selected in S602. In the description of FIG. 6 below, the one RX selected in S607 will be referred to as the target RX. Then, in S608, the communication control unit 301 transmits a message to RXs other than the target RX (non-target RXs) to notify them that they have not been selected. This message is the same as the message used in the notification of S411 in FIG. 4, and therefore description thereof will be omitted.

[0078] When the non-target RX receives the message, it controls the TX 100 so that it is not charged or supplied with power (for example, it disconnects the connection to the load (charging circuit, battery, etc.)). That is, the non-target RX controls the switch unit 209 (FIG. 2) to disconnect the load (charging circuit, battery, etc.) and does not supply the received power to the load (charging circuit, battery, etc.).

[0079] Next, the TX 100 transitions to the negotiation phase (S609) and then to the calibration phase (S610). In the calibration phase, the target RX notifies the TX 100 of a predetermined received power value (received power value in a light load state / received power value in a maximum load state) based on the WPC standard, and the power transmission control unit 302 of the TX 100 performs adjustments for efficient power transmission. The received power value notified to the TX 100 can be used for foreign object detection processing using the power loss method. The processing in the calibration phase is similar to the processing of S414 in FIG. 4, and therefore a description thereof will be omitted.

[0080] In S611, the control unit 101 associates the calibration data acquired in the calibration phase with the information of the target RX acquired in S606 (device configuration information (capability information) and RX identification information) and stores them in the memory 106. Then, in S612, the control unit 101 determines whether the selection and switching of all power transmitting antennas has been completed.

[0081] Through the above processing from S602 to S612, the TX 100 can individually acquire (derive) calibration data for each RX in a time-division manner for all RXs placed on the TX 100. Next, in S613, the TX 100 transitions to the power transfer phase. Then, the processing ends in S614.

[0082] In the power transfer phase (S613), the TX 100 controls the TX 100 to transmit power to multiple RXs placed on the TX 100 in a time-division manner. Detailed operations in the power transfer phase will be described below with reference to FIG. 7. FIG. 7 is a flowchart of the processing in the power transfer phase in this embodiment. The processing in S701 to S704 is the same as S501 to S504 in FIG. 5, and therefore a description thereof will be omitted. After the processing in S704, in S705, the power transmission control unit 302 transmits power to the target RX.

[0083] During power transmission, the foreign object detection unit 303 detects changes in the power transmission and reception state within the power transmission range of the TX 100 (for example, a change in the state on the TX 100) (S706). For example, the foreign object detection unit 303 detects a foreign object using the calibration data of the target RX acquired in the calibration phase (S610 in FIG. 6) with the power loss method described above. If a foreign object is detected, the process returns to S602 in FIG. 6 (processing after TX startup). On the other hand, it is also possible that the change in the power transmission and reception state is not due to a foreign object, but rather to an increase or decrease in the number of RXs placed on the TX 100. Because an increase or decrease in the number of RXs on the TX 100 also causes a change in the power loss described above, the foreign object detection unit 303 can detect an increase or decrease in the number of RXs on the TX 100 using the power loss method.

[0084] If a change in the power transmission and reception state is detected in S706, by returning to the step after TX startup in the flow of Fig. 6, power can be transmitted appropriately to all RXs even if, for example, the number of RXs placed on the TX 100 increases or decreases. If no change in the power transmission and reception state is detected, the process proceeds to S707, and the control unit 101 determines whether a predetermined counter (a period specified by the predetermined counter) has expired. This counter is, for example, a counter that counts time, the number of intermittent power transmissions, or the number of communication packets or frames. If the counter has expired in S707 (for example, if a predetermined condition / number is met) (Yes in S707), the process returns to S702, and the TX 100 selects another RX and transmits power.

[0085] If the predetermined counter has not finished counting in S707 (No in S707), the process proceeds to S708, where the control unit 101 determines whether or not power transmission to the target RX has been completed. If the result of the determination is, for example, that the RX is not yet fully charged and power transmission has not been completed, the process returns to S705, where the power transmission control unit 302 continues power transmission. If it is determined in S708 that power transmission to the target RX has been completed, the process proceeds to S709, where the control unit 101 determines whether or not power transmission to all RX has been completed. If power transmission to all RX has not been completed, the process returns to S702, where the control unit 101 selects another RX to which power transmission has not been completed, and the power transmission control unit 302 transmits power to the selected RX (target RX). If power transmission to all RXs placed on the TX 100 has been completed, the process proceeds to S710, where it ends.

[0086] As described above, in this embodiment, the TX100 first sets a specific RX among the multiple RXs placed on the TX100 as the target RX, controls the RXs other than the target RX so that they are not charged or supplied with power from the TX100, and then derives (acquires) calibration data for the target RX (FIG. 6). The TX100 then acquires calibration data for all RXs. Thereafter, in the power transfer phase, the TX100 sets a specific RX among the multiple RXs placed on the TX100 as the target RX, controls the RXs other than the target RX so that they are not charged or supplied with power from the TX100, and then transmits power to the target RX using the calibration data that has already been derived (FIG. 7). This allows the state of each RX when the calibration data is derived to match the state of each RX at the time of power transmission, making it possible for the TX100 to properly complete power transmission to all RXs.

[0087] Note that the first embodiment has been described based on the flows in Figures 4 and 5, and the second embodiment has been described based on the flows in Figures 6 and 7. However, this combination can be changed, and it is also possible to realize processing that combines the flows in Figures 4 and 6, and Figures 5 and 7.

[0088] [Embodiment 3] In the first and second embodiments, a control method for appropriately transmitting power to a plurality of RXs has been described. In this embodiment, another control method for appropriately transmitting power to a plurality of RXs will be described. Below, differences from the first and second embodiments will be described, and a description of common parts will be omitted.

[0089] [Processing flow by power transmission device] 8 shows a flowchart of the processing executed by the TX100 in this embodiment. This processing can be realized, for example, by the control unit 101 of the TX100 executing a program read from the memory 106. Note that at least part of the following procedure may be realized by hardware. In this case, the hardware can be realized, for example, by using a predetermined compiler to automatically generate a dedicated circuit using a gate array circuit such as an FPGA from a program for implementing each processing step.

[0090] The processes of S801 to S806 are the same as S401 to S406 in FIG. 4 described in the first embodiment, and therefore description thereof will be omitted. In S807, the control unit 101 selects one RX. This RX may be the RX detected using the power transmitting antenna selected in S802. In the description of FIG. 8 below, the one RX selected in S807 will be referred to as the target RX. Then, in S808, the communication control unit 301 transmits a message to RXs other than the target RX (non-target RXs) to notify them that they have not been selected. This message is the same as the message used in the notification of S411 in FIG. 4, and therefore description thereof will be omitted.

[0091] When the non-target RX receives the message, it controls the TX 100 so that it is not charged or supplied with power (for example, it disconnects the connection to the load (charging circuit, battery, etc.)). That is, the non-target RX controls the switch unit 209 (FIG. 2) to disconnect the load (charging circuit, battery, etc.) and does not supply the received power to the load (charging circuit, battery, etc.).

[0092] Next, the TX 100 transitions to the negotiation phase (S809) and then to the calibration phase (S810). In the calibration phase, the target RX notifies the TX 100 of a predetermined received power value (received power value in a light load state / received power value in a maximum load state) based on the WPC standard, and the power transmission control unit 302 of the TX 100 makes adjustments to transmit power efficiently. The received power value notified to the TX 100 can be used for foreign object detection processing using the power loss method. The processing in the calibration phase is similar to the processing of S414 in FIG. 4, so a description thereof will be omitted.

[0093] In S811, the control unit 101 stores in the memory 106 the calibration data acquired in the calibration phase in association with the information of the target RX acquired in S806 (device configuration information (capability information) and RX identification information).

[0094] Next, in S812, the TX 100 transitions to the Power Transfer phase. Then, in S813, the control unit 101 determines whether the selection and switching of all power transmitting antennas has been completed. If the switching of all antennas has not been completed, the process returns to S802, and the control unit 101 selects another antenna that has not yet been selected. If the switching of all antennas has been completed, the process proceeds to S814 and ends.

[0095] In the power transfer phase (S812), the TX 100 controls the multiple RXs placed on the TX 100 to transmit power in a time-division manner. Detailed operations in the power transfer phase will be described below with reference to Fig. 9. Fig. 9 is a flowchart of the processing in the power transfer phase in this embodiment.

[0096] When the TX 100 starts the power transfer phase (S901), the power transmission control unit 302 transmits power to the target RX (S902). During power transmission, the foreign object detection unit 303 detects changes in the power transmission and reception state (e.g., a change in the state on the TX 100) within the power transmission range of the TX 100 (S706). For example, the foreign object detection unit 303 detects a foreign object using the calibration data of the target RX acquired in the calibration phase (S810 in FIG. 8) with the power loss method described above. If a foreign object is detected, the process returns to S802 in FIG. 8 (processing after TX startup). On the other hand, the change in the power transmission and reception state may not be due to a foreign object, but may be due to an increase or decrease in the number of RXs placed on the TX 100. Because an increase or decrease in the number of RXs on the TX 100 also causes a change in the power loss described above, the foreign object detection unit 303 can detect an increase or decrease in the number of RXs on the TX 100 using the power loss method.

[0097] If a change in the power transmission and reception state is detected in S903, the process returns to the step after TX startup in the flow of Fig. 8, so that power is transmitted appropriately to all RXs even if, for example, the number of RXs placed on the TX 100 increases or decreases. If no change in the power reception state is detected, the process proceeds to S904, and the control unit 101 determines whether power transmission to the target RX is complete. If it is determined that power transmission is complete because, for example, the RX is fully charged, the process proceeds to S905 and is completed. If it is determined that power transmission is not complete, the process proceeds to S902, and the power transmission control unit 302 continues power transmission.

[0098] As described above, in this embodiment, the TX100 first sets a specific RX among the multiple RXs placed on the TX100 as the target RX, controls the RXs other than the target RX so that they are not charged or supplied with power from the TX100, and then derives (acquires) calibration data for the target RX (FIG. 8). The TX100 then acquires calibration data for all RXs. Thereafter, in the power transfer phase, the TX100 sets a specific RX among the multiple RXs placed on the TX100 as the target RX, controls the RXs other than the target RX so that they are not charged or supplied with power from the TX100, and then transmits power to the target RX using the calibration data that has already been derived (FIG. 9). This allows the state of each RX when the calibration data is derived to match the state of each RX at the time of power transmission, making it possible for the TX100 to properly complete power transmission to all RXs.

[0099] The control method for appropriately transmitting power to multiple RXs has been described above using three embodiments. In the above embodiments, a method for detecting a state change on the power transmitting device using a power loss method was described as a foreign object detection function. However, because the Q-factor changes depending on an increase or decrease in the number of RXs on the TX, it is also possible to detect an increase or decrease in the number of RXs on the TX using a Q-factor measurement method. Therefore, when the TX detects a change in the power transmission / reception state (e.g., a state change on the TX) using the Q-factor measurement method performed in the negotiation phase, the TX may be controlled to return to operation after TX startup. That is, in the first embodiment, the process returns from S506 in FIG. 5 to S402 in FIG. 4; in the second embodiment, the process returns from S706 in FIG. 7 to S602 in FIG. 6; and in the third embodiment, the process returns from S903 in FIG. 9 to S802 in FIG. 8.

[0100] Alternatively, instead of the Q-factor measurement method, the TX may be controlled to return to operation after startup when a change in the power transmission / reception state in the TX is detected based on measurement results such as the resonant frequency of the power transmitting antenna, the sharpness of the resonant curve, the inductance value of the power transmitting antenna, the coupling coefficient between the power transmitting antenna and an object placed on the TX, the electrical characteristics of the power transmitting unit including the power transmitting antenna of the TX, or measurement results from sensors such as a photoelectric sensor, eddy current displacement sensor, contact displacement sensor, ultrasonic sensor, image discrimination sensor, or weight sensor mounted on the TX. Furthermore, the TX may periodically send an Analog Ping from a power transmitting antenna other than the one that communicates and transmits power to the RX, and when it detects that an object has been placed on the TX, it may be controlled to return to operation after startup. This is because in these cases, there is a possibility that a new RX or foreign object may be present near the power transmitting antenna.

[0101] In this way, the TX measures the power loss between the TX and RX in a time-division manner for each of the multiple RXs that are present within the TX's power transmission range when there is no foreign object between them, and also transmits power to each of the RXs in a time-division manner, thereby improving the accuracy of foreign object detection during the power transmission process.

[0102] [Other embodiments] In the first to third embodiments, the power transmitting device has been described as being configured such that one power transmitting antenna selected from multiple power transmitting antennas is connected to one power transmitting unit. However, multiple power transmitting units may be connected to one power transmitting antenna. That is, when the power transmitting device has a first power transmitting unit (power transmitting circuit) and a second power transmitting unit (power transmitting circuit), and the first power transmitting antenna and the second power transmitting antenna are included, either the first power transmitting unit or the second power transmitting unit may be connectable to the first power transmitting antenna. Here, consider a case where the first power transmitting unit (power transmitting circuit) is connected to the first power transmitting antenna and power is being transmitted to the power receiving device, but the power transmitting unit (power transmitting circuit) connected to the first power transmitting antenna is switched from the first power transmitting unit (power transmitting circuit) to the second power transmitting unit (power transmitting circuit). If the electrical characteristics of the first power transmitting unit and the second power transmitting unit are the same, the above-mentioned calibration data does not change, and therefore it is possible to transmit power from the second power transmitting unit (power transmitting circuit) to the power receiving device using the already acquired calibration data in the manner described in the first to third embodiments. On the other hand, if the electrical characteristics of the first power transmitting unit and the second power transmitting unit are different, the above-mentioned calibration data also changes, and therefore it is not possible to transmit power using the already acquired calibration data. Therefore, it is possible to derive (acquire) calibration data again in the manner described in the first to third embodiments and transmit power from the second power transmitting unit (power transmitting circuit) to the power receiving device using the calibration data. At this time, the power transmitting device stores in memory information that associates information on the RX to be transmitted with information on the power transmitting antenna used for power transmission and information on the power transmitting unit (power transmitting circuit) used for power transmission.

[0103] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0104] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0105] 100: Power transmitting device (TX), 200~220: Power receiving device (RX)

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