Power transmission device and method performed by the power transmission device

Abstract

To appropriately transmit electric power from a power transmission device to a plurality of power reception devices.SOLUTION: A power transmission device 100 that wirelessly transmits electric power to a plurality of power reception devices 200 in a time sharing scheme derives a plurality of power loss data between the power transmission device 00 and the plurality of power reception devices 200 on the basis of a plurality of received powers received from the plurality of power reception devices 200, and detects an abnormality in a power transmission available range of the power transmission device 100 on the basis of the plurality of power loss data.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] In recent years, technical development of wireless power transmission systems has been widely carried out. Patent Document 1 discloses a power transmitting device and a power receiving device that comply with a standard (WPC standard) established by the Wireless Power Consortium (WPC), a standardization organization for wireless charging standards. Patent Document 2 discloses a method of foreign object detection in the WPC standard. Here, the foreign object is a conductive object such as a metal piece. In the WPC standard, first, the power loss in a state where there is no foreign object between the power transmitting device and the power receiving device is calculated in advance from the difference between the power transmitted by the power transmitting device and the power received by the power receiving device, and the calculated value is considered to be the power loss in a normal state (a state where there is no foreign object) during the power transmission process. Then, if the power loss between the power transmitting device and the power receiving device calculated during the subsequent power transmission is different from the power loss in the normal state, which is the reference, by a threshold value or more, it is determined that there is a foreign object or that there is a possibility that a foreign object exists. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-56959 A [Patent Document 2] JP 2017-70074 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a power transmission device capable of charging a plurality of power receiving devices, the power loss between the power transmission device and the first power receiving device is different from the power loss between the power transmission device and the second power receiving device, and therefore, if the same power loss is used as the power loss in the normal state as a reference, there is a problem that the accuracy of foreign object detection is reduced. In addition, when the first power receiving device and the second power receiving device are placed on the power transmission device, the power loss between the power transmission device and the first power receiving device may be affected by the second power receiving device. Similarly, the power loss between the power transmission device and the second power receiving device may be affected by the first power receiving device. Therefore, when the state (number, etc.) of the power receiving devices placed on the power transmission device changes, the power loss between the power transmission device and the power receiving device in the normal state calculated in advance also changes, and there is a problem that the accuracy of foreign object detection is reduced.

[0005] The present invention has been made in consideration 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 identification information from one or more power receiving devices; A determination means for determining that there are a plurality of power receiving devices based on the acquired identification information; A selection means for selecting a coil corresponding to each of the plurality of power receiving devices when the plurality of power receiving devices is present; a power transmitting means for wirelessly transmitting power to a first power receiving device included in the plurality of power receiving devices via a first coil included in the plurality of coils and corresponding to the first power receiving device, and for wirelessly transmitting power to a second power receiving device included in the plurality of power receiving devices 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 via a coil in the vicinity of the first coil while wirelessly transmitting power to the first power receiving device via the first coil. Effect of the Invention

[0007] It is possible to appropriately transmit power from the power transmitting device to a plurality of power receiving devices. [Brief description of the drawings]

[0008] [Figure 1] 2 is a block diagram showing a configuration example of a power transmitting device. FIG. [Diagram 2]2 is a block diagram showing a configuration example of a power receiving device; [Diagram 3] 4 is a block diagram showing an example of a functional configuration of a control unit of the power transmitting device. FIG. [Figure 4] 4 is a flowchart of a process executed by the power transmitting device according to the first embodiment. [Diagram 5] 4 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 the second embodiment. [Figure 7] 11 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] 13 is a flowchart of a process in a power transfer phase according to the third embodiment. [Figure 10] 1A and 1B are diagrams illustrating a foreign object detection method based on a power loss technique. [Figure 11] 1 shows a configuration example of a wireless power transmission system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

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

[0011] First, the power transmitting device transmits power to the power receiving device, and the power transmitting device receives the received power value Pr1 from the power receiving device. Then, the power transmitting device 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 becomes the minimum power. 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 (charging circuit, battery, etc.). This state may be called a light load state. At this time, the power transmitting device may 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 the value of the received power value Pr2 received by the power receiving device from 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 becomes 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 can 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). Then, the power transmitting device linearly interpolates the points 1000 and 1001 to create a straight line 1002. The straight line 1002 shows the relationship between the transmission power and the reception power in a state where no foreign object exists 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 is Pr3 from point 1003 on line 1002 which 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 a value Pr3-Pr3' (=Ploss_FO) by subtracting the received power value Pr3' actually received from the power receiving device from the received power value Pr3 in a state where the foreign object is not present. This Ploss_FO can be considered as the power loss consumed by a foreign object when the foreign object is present between the power transmitting device and the power receiving device. Therefore, when 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 "foreign object is present" or "there is a possibility that a foreign object is present."

[0013] Alternatively, the power transmitting device may calculate in advance the power loss Pt3-Pr3 (Ploss3) between the power transmitting device and the power receiving device 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. Then, the power Ploss_FO that would have been consumed by the foreign object may be calculated by Ploss3'-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, the method of calculating Ploss3'-Ploss3 (=Ploss_FO) is basically described, but the method of calculating Pr3-Pr3' (=Ploss_FO) is also applicable. This concludes the description of foreign object detection based on the power loss method.

[0015] <Outline of the foreign object detection method according to the present embodiment> Next, a foreign object detection method in a power transmitting device capable of transmitting power to a plurality of power receiving devices will be described. Fig. 11 shows an example of the configuration of a wireless power transmission system in this embodiment. In the following, the power transmitting device may be called TX and the power receiving device may be called RX. The configurations of TX100 and RX200-220 are shown in Figs. 1 and 2, respectively, and will be described in detail later.

[0016] The TX100 transmits power to the RX200, 210, and 220 placed on the TX100 (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 RX200, 210, and 220 each receive the power transmitted from the TX100 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, consider the power loss between each TX and multiple RXs. In a TX capable of transmitting (charging) power to multiple RXs (e.g., a first RX and a second RX), the power loss between the TX and the first RX is different 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 of the RX200. 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 of the RX210. In this case, the power loss between the TX100 and RX200 is different from the power loss between the TX100 and RX210. The reasons for this include 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 effect of RX200 on the electrical characteristics of the power transmitting antenna 105b, the effect of RX210 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 a battery)), etc. For this reason, if the same line showing the power loss between TX and RX when no foreign object exists between TX and RX, or the relationship between the transmitted power and the received power as shown in Fig. 10 is used between TX and the first RX and between TX and the second RX, a problem occurs in that the accuracy of foreign object detection decreases.

[0019] In addition, when the first RX and the 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, when there is a change in the state of the RXs placed on the TX (the number of units, the placement position, etc.), the power loss between the TX and the RX calculated in advance when there is no foreign object between the TX and the RX, or the straight line showing the relationship between the transmission power and the reception power as shown in Fig. 10, changes occur, resulting in a problem of a decrease in the accuracy of foreign object detection.

[0020] In order to solve such a problem, the TX calculates "power loss between TX and the first RX in a state where there is no foreign object" and "power loss between TX and the second RX in a state where there is no foreign object" separately as the power loss between TX and RX in a state where there is no foreign object, which is calculated in advance. Then, when transmitting power to the first RX, the TX uses "power loss between TX and the first RX in a state where there is no foreign object" as a reference, and judges that "foreign object is present" or "foreign object may be present" if the power loss between TX and the first RX calculated during power transmission is different from the "power loss between TX and the first RX in a state where there is no foreign object" by a threshold or more. Similarly, when transmitting power to the second RX, the TX uses "power loss between TX and the second RX in a state where there is no foreign object" as a reference, and judges that "foreign object is present" or "foreign object may be present" if the power loss between TX and the second RX calculated during power transmission processing is different from the "power loss between TX and the second RX in a state where 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 calculates the power loss for each RX during power transmission, compares them, and determines whether or not there is a foreign object. This makes it possible to appropriately detect a foreign object even in a wireless power transmission system in which the TX transmits power to multiple RXs.

[0022] As described above with reference to FIG. 10, the TX can calculate the value Pr3-Pr3' (=Ploss_FO) obtained by subtracting the received power value Pr3' actually received from the RX from the received power value Pr3 in the absence of a foreign object, and determine the presence of a foreign object based on whether or not the calculated value is equal to or greater than a predetermined threshold. That is, the TX acquires in advance, in the absence of a foreign object, the "received power value from the first RX in the absence of a foreign object" and the "received power value from the second RX in the absence of a foreign object" separately. Then, when transmitting power to the first TX, the TX determines that "foreign object is present" or "foreign object may be present" if the difference between the "received power value from the first RX in the absence of a foreign object" 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 "foreign object is present" or "foreign object may be present" if the difference between the "received power value from the second RX in the absence of a foreign object" 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 manner, 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 refers to, 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 effect of RX200 on the electrical characteristics of the power transmitting antenna 105b, the effect of RX210 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 a battery)).

[0024] In order to achieve this, for example, first, when calculating the power loss between TX and RX in a state where no foreign object exists (or when receiving a received power value from RX) in advance, the TX selects one RX (target RX) to be a target from among multiple RXs. The TX controls the non-target RX so that the power transmitted from the TX is not charged or supplied to the RX. The state where the transmitted power is not charged or supplied is, for example, a state where the connection to the load (such as a charging circuit or a battery) is cut off. Then, the TX calculates the power loss between the TX and the target RX using a power transmission antenna capable of transmitting power to the target RX. In a similar state, when calculating the power loss between TX and RX during power transmission (or when receiving a received power value from RX), the TX calculates the power loss between the TX and the target RX using a power transmission antenna capable of transmitting power to the target RX. After that, the TX compares the power loss between the TX and the target RX calculated during power transmission with the power loss between the TX and the target RX calculated in advance in a state where no foreign object exists, and judges the presence or absence of a foreign object between the TX and the target RX. Alternatively, the TX determines the presence or absence of 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 combining 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 transmission antenna as described above), it becomes possible to appropriately detect a foreign object even in a wireless power transmission 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 RX200 on the electrical characteristics of the power transmitting antenna 105b, the influence of the RX210 on the electrical characteristics of the power transmitting antenna 105a, 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 a 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 appropriately detect a foreign object in a wireless power transmission system in which the TX transmits power to multiple RXs.

[0027] [System configuration] The wireless power transmission system in 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 enable charging of the battery. The TX100 is an electronic device that wirelessly transmits power to the RX200, 210, and 220 placed on the TX100. In the following, a case where the RX200, 210, and 220 are placed on the TX100 will be described as an example. 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] Moreover, the RX200, 210, 220 and the TX100 may have a function of executing an application other than contactless charging. An example of the RX200, 210, 220 is a smartphone, and an example of the TX100 is an accessory device for charging the smartphone. The RX200, 210, 220 and the TX100 may be a storage device such as a tablet, a hard disk device, or a memory device, or may be an information processing device such as a personal computer (PC). The RX200, 210, 220 and the TX100 may be, for example, an image input device such as an imaging device (a camera, a video camera, etc.) or a scanner, or may be an image output device such as a printer, a copier, or a projector. The TX100 may be a smartphone. In this case, the RX200, 210, 220 may be another smartphone or a wireless earphone. The TX100 may be a charger installed in a console or the like in a car.

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

[0030] Here, the power transmission control according to the WPC standard will be described by taking the TX100 as the TX and the RX200, 210, and 220 as the RX as an example. In the WPC standard, the magnitude of the power guaranteed when the RX200, 210, and 220 receive power from the TX100 is stipulated by a value called Guaranteed Power (hereinafter referred to as "GP"). The GP indicates a power value that guarantees the output to the loads (e.g., charging circuits, batteries, etc.) of the RX200, 210, and 220 even if the positional relationship between the RX200, 210, and 220 and the TX100 fluctuates and the power transmission efficiency between the power receiving antenna and the power transmitting antenna decreases. For example, when the GP is 5 watts, the TX100 performs power transmission by controlling so that it can output 5 watts to the loads in the RX200, 210, and 220, even if the positional relationship between the power receiving antenna and the power transmitting antenna fluctuates 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) that is not an RX around the TX100 (near the receiving antenna). More specifically, it specifies a power loss method that detects foreign objects based on the difference between the transmission power in the TX100 and the receiving power in the RX200, 210, and 220, and a Q-factor measurement method that detects foreign objects based on changes in the quality factor (Q-factor) of the transmitting antenna (transmitting coil) in the TX100. Foreign object detection using the power loss method is performed during power transmission (power transfer phase, described below). Foreign object detection using the Q-factor measurement method is performed before power transmission (negotiation phase or renegotiation phase, described below).

[0032] The RX200, 210, 220 and the TX100 according to this embodiment communicate for power transmission and reception control based on the WPC standard. The WPC standard specifies a number of 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. The phase before the power transmission may include a selection phase, a ping phase, an identification and configuration phase, a negotiation phase, and a calibration phase. In the following, the identification and configuration phase is referred to as an I&C phase.

[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 conductor piece has been placed on the charging stand of the TX100). The TX100 detects at least one of the voltage value and current value 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 a larger power than the Analog Ping. The power of the Digital Ping is sufficient to start 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, and 220 by receiving a response from the RX200, 210, and 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 this end, 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 the 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 and the power transmission capability of the TX100. The TX100 also performs foreign object detection processing using the Q-factor measurement method in response to requests from the RX200, 210, and 220. The WPC standard also specifies a method of once transitioning to the power transfer phase, and then performing the same processing as in the negotiation phase again at the request of the RX. The phase transitioning from the power transfer phase and performing these processes 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 in a light load state / received power value in a maximum load state) based on the WPC standard, and the TX100 performs adjustments for efficient power transmission. The received power value notified to the TX100 can be used for foreign object detection processing by the power loss method.

[0038] In the power transfer phase, control is performed for starting and continuing power transmission, and stopping power transmission due to an error or full charge. For this power transmission and reception control, the TX100 and the RX200, 210, and 220 use the same power transmission antenna (power transmission coil) and power receiving antenna (power receiving coil) as those used when performing wireless power transmission based on the WPC standard to perform communication by superimposing a signal on the electromagnetic waves transmitted from the power transmission antenna or the power receiving antenna. Note that the range in which communication based on the WPC standard is possible between the TX100 and the RX200, 210, and 220 is approximately the same as the power transmission range of the TX100.

[0039] [Configuration of power transmitting device and power receiving device] Next, the configuration of the power transmitting device and the power receiving device according to the present embodiment will be described with reference to FIG. 1 and FIG. 2. FIG. 1 is a block diagram showing a configuration example of a TX (power transmitting device) 100 according to the present embodiment. FIG. 2 is a block diagram showing a configuration example of an RX (power receiving device) 200 according to the present embodiment. Note that the RX210 and the RX220 have the same configuration as the RX200. Note that the configuration described below is merely an example, and a part (in some cases, the whole) of the configuration described may be replaced with another configuration that performs a similar function or may be omitted, and further configuration may be added to the configuration described. Furthermore, one block described below may be divided into multiple blocks, or multiple blocks may be integrated into one block. Furthermore, each functional block described below is assumed to have a function implemented as a software program, but a part or all of the functional blocks included in this functional block may be implemented as 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 of these functional blocks may be implemented in 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 performs control related to power transmission control including communication for device authentication in the TX 100. The control unit 101 may also perform control for executing 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 be configured with hardware dedicated to a specific process, such as an application specific integrated circuit (ASIC). The control unit 101 may also be configured with an array circuit, such as a field programmable gate array (FPGA) 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 the 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 in a half-bridge or full-bridge configuration using a FET (Field Effect Transistor). In this case, the power transmitting unit 103 includes a gate driver that controls ON / OFF of the FET.

[0044] The power transmitting unit 103 controls the intensity of the electromagnetic waves to be output by adjusting the voltage (power transmission voltage) or current (power transmission current) or both input to the power transmitting antennas 105a to 105c under the control of the control unit 101. Increasing the power transmission voltage or power transmission current increases the intensity of the electromagnetic waves, and decreasing the power transmission voltage or power transmission current decreases the intensity of the electromagnetic waves. Furthermore, the power transmitting unit 103 performs output control of AC frequency power so that power transmission from the power transmitting antennas 105a to 105c is started or stopped based on an instruction from the control unit 101. Furthermore, the power transmitting unit 103 is assumed to have a capacity to supply power sufficient to output 15 watts (W) to a charging unit of RX (charging unit 206 (FIG. 2) in the case of RX200 to 220) that complies with the WPC standard.

[0045] The communication unit 104 performs communication with RX for power transmission control based on the WPC standard as described above under the control of the control unit 101. The communication unit 104 modulates electromagnetic waves output from the power transmitting antennas 105a to 105c, transmits information to RX, and performs communication. The communication unit 104 also demodulates the electromagnetic waves output from the power transmitting antennas 105a to 105c and modulated by RX to obtain information transmitted by 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 perform communication with RX by communication based on a standard other than the WPC standard using antennas other than the power transmitting antennas 105a to 105c, or may perform communication with RX by selectively using a plurality of communications.

[0046] The memory 106 can store the control program, as well as the status of the TX 100 and the 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 the 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 realized as one 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 (if the RX200 is a smartphone, the entire smartphone) in cooperation with an OS (Operating System) being executed.

[0050] The control unit 201 may be configured with hardware dedicated to a specific process, such as an ASIC. The control unit 201 may 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 during execution of various processes in the memory 208. The control unit 201 may 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, blinking or color changes of LEDs, audio output from a speaker, vibration of the RX200 main unit, etc. The UI unit 202 is realized by a liquid crystal panel, a speaker, a vibration motor, etc.

[0052] The power receiving unit 203 obtains, 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. Then, the power receiving unit 203 converts the AC power into DC or AC power of a predetermined frequency, and outputs the power to the charging unit 206 that performs processing for charging 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 is assumed to have the capacity to supply power for the charging unit 206 to charge the battery 207 and to supply power sufficient to output 15 watts of power to the charging unit 206. The switch unit 209 is for controlling whether or not the received power is supplied to the battery (load). If the switch unit 209 connects the charging unit 206 and the battery 207, the received power is supplied to the battery 207. If the switch unit 209 disconnects the charging unit 206 and the battery 207 by the switch, 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 one block in FIG. 2, it is also possible to realize the switch unit as a part of the charging unit 206. The communication unit 204 performs communication for power reception control based on the WPC standard as described above with the communication unit 104 of the TX100. The communication unit 204 demodulates the electromagnetic wave input from the power receiving antenna 205 to obtain information transmitted from the TX100. Then, the communication unit 204 performs communication with the TX100 by load modulating the input electromagnetic wave to superimpose a signal related to information to be transmitted to the TX100 on the electromagnetic wave. The communication unit 204 may communicate with the TX 100 using an antenna other than the power receiving antenna 205 and a standard other than the WPC standard, or may communicate with the TX 100 by selectively using a plurality of communication methods.

[0053] The memory 208 stores the control program and also stores the states of the TX100 and the RX200. For example, the state of the RX200 is acquired by the control unit 201, and the state 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 includes 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 a foreign object by measuring the transmission power in the power transmission unit 103 and the Q value in 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 a foreign object detection process 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 a foreign object detection process using a function of detecting an opposing device according to the NFC standard. The foreign object detection unit 303 can also detect a change in the state of the TX 100 as a function other than detecting a foreign object. 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 an 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 synchronizing the programs through event processing or the like.

[0057] [Processing flow by power transmission device] Next, the flow of the process executed by the TX100 will be described. Fig. 4 shows a flowchart of the process executed by the TX100 in this embodiment. This process 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 a 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 realizing each processing step.

[0058] This process starts when the TX100 is started (S401). Alternatively, this process may 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 supply. This process may also be started by other triggers. 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 moves to a 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 an Analog Ping periodically. If an object is detected in S404 (Yes in S404), the TX100 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 TX100 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 the RX information acquired in S406 and information associating the RX 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 the power transmitting antennas are completed. If the switching of all the antennas is not completed, the process proceeds to S402, and the control unit 101 controls the antenna switching unit 107 to select another power transmitting antenna. If the selection and switching of all the power transmitting antennas is 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 an RX that can be recognized by each power transmitting antenna. Also, the TX100 can recognize information on all RXs present on the TX100.

[0061] Next, in S409, the control unit 101 judges whether or not there are multiple RXs placed on the TX 100 based on the results of S401 to S408. If it is judged in S409 that there are multiple RXs placed on the TX 100 (Yes in S409), the process proceeds to S410, and if it is judged 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 explanation of FIG. 4, the one RX selected in S410 is referred to as the target RX. Then, in S411, the communication control unit 301 transmits a message to the RXs other than the target RX (non-target RXs) to make them recognize that they have not been selected.

[0062] This message may be a message for notifying all RXs of the information of the target RX (selected RX), or may be a message for notifying all RXs of the information of the non-target RX (not selected RX). Since these messages need to be notified to all the multiple RXs on the TX100, they are transmitted from all the multiple power transmission antennas 105 of the TX100. 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 transmission 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 for a predetermined time. Also, this message is transmitted from a power transmission coil that can communicate with at least the target RXs.

[0063] When the non-target RX receives the message, it controls so that it is not charged or supplied with power from the TX 100 (for example, it cuts off the connection to the load (charging circuit, battery, etc.)). That is, the RX controls the switch unit 209 (FIG. 2) to cut off 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) capable of transmitting power to the target RX (corresponding to the target RX), and sets the antenna in a state in which communication and power transmission to the target RX are possible. Next, the TX100 transitions to a negotiation phase (S413), and transitions to a 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 performs adjustments for efficient power transmission. The received power value notified to the TX100 can be used for foreign object detection processing by the power loss method.

[0065] In the calibration phase, the TX100 derives the relationship between the transmission power and the received power in a state where there is no foreign object, as described above with reference to FIG. 10. Specifically, the foreign object detection unit 303 of the TX100 derives data (power loss data) indicating the power loss between the TX and RX in a state where there is no foreign object, using a predetermined received power value (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 based on the WPC standard (corresponding to the line 1002 in FIG. 10). Hereinafter, the power loss data is called calibration data. The calibration data can be used for foreign object detection processing by the power loss method. The explanation of foreign object detection based on the power loss method is as above. That is, when 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 judges that "there is a foreign object" or that "there is a possibility that a foreign object exists."

[0066] In S415, the control unit 101 stores the calibration data acquired in the calibration phase in association with the information of the target RX (S407) in the memory 106. Then, in S416, the control unit 101 judges whether or not the calibration data of all RXs placed on the TX 100 has been acquired. This can be judged by checking whether the information of the RXs and the calibration data acquired in S415 all correspond to each other, since the TX 100 has acquired the information of all RXs on the TX 100 in S401 to S408.

[0067] Through the above processes 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 process ends in S418.

[0068] In the power transfer phase (S417), the TX100 controls the multiple RXs mounted on the TX100 to transmit power in a time-division manner. Hereinafter, detailed operations in the power transfer phase will be described 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 TX100 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 TX100 (S502). In the following description of FIG. 5, the one RX selected in S502 is 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 the same as the message used in the notification in S411 of 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, the connection to the load (such as the charging circuit and battery) is cut off). 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) capable of transmitting power to the target RX (corresponding to the target RX), and brings the antenna into a state in which 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 a change in the power transmission / reception state (e.g., a state change on the TX 100) in the power transmission range of the TX 100 (S506). For example, the foreign object detection unit 303 detects a foreign object by the power loss method described above using the calibration data of the target RX acquired in the calibration phase (S414 in FIG. 4). 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, the change in the power transmission / 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. Since the 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] When a change in the power transmission / reception state is detected in S506, the process returns to the state after the TX is started in the process flow of FIG. 4, so that power can be appropriately transmitted to all RXs even when, for example, the number of RXs placed on the TX100 increases or decreases. The foreign object detection unit 303 of the TX100 periodically monitors the change in the power transmission / reception state during power transmission by the power transmission control unit 302 until the power transmission ends (No in S506, No in S507). When the TX100 ends the power transmission without detecting a change in the power transmission / reception state (Yes in S507), it stores information on the target RX (RXs for which power transmission has been completed) in the memory 106. Then, the process proceeds to S508, where the control unit 101 checks against the information on the RXs already stored to determine whether power transmission has been completed for all RXs. When power transmission has been completed for all RXs, the process ends in S509, and when power transmission has not been completed for all RXs, the process returns to S502 (after the start of the Power Transfer phase). 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-mentioned 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 of the RXs.

[0074] In this embodiment, first, the TX100 sets a specific RX among the multiple RXs placed on the TX100 as a target RX, controls the non-target RXs so that they are not charged or powered by the TX100, and derives (acquires) calibration data for the target RX (FIG. 4). Then, the TX100 acquires calibration data for all RXs. After that, in the power transfer phase, the TX100 sets a specific RX among the multiple RXs placed on the TX100 as a target RX, controls the non-target RXs so that they are not charged or powered by the TX100, and transmits power to the target RX using the calibration data already derived (FIG. 5). This allows the TX100 to properly complete power transmission to all RXs by matching the state of each RX when the calibration data is derived with the state of each RX when power is transmitted.

[0075] [Embodiment 2] In the first embodiment, a control method for appropriately transmitting power to a plurality of RXs has been described. In the present 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 descriptions of common parts will be omitted.

[0076] [Processing flow by power transmission device] 6 shows a flowchart of the process executed by the TX 100 in this embodiment. This process can be realized, for example, by the control unit 101 of the TX 100 executing a program read from the memory 106. Note that at least a 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 realizing each processing step.

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

[0078] When the non-target RX receives the message, it controls so that it is not charged or powered by the TX100 (for example, it cuts off the connection to the load (charging circuit, battery, etc.)). That is, the non-target RX controls the switch unit 209 (FIG. 2) to cut off the load (charging circuit, battery, etc.) and does not supply the received power to the load (charging circuit, battery, etc.).

[0079] Next, the TX100 transitions to a negotiation phase (S609) and transitions to a calibration phase (S610). 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 power transmission control unit 302 of the TX100 performs adjustments for efficient power transmission. The received power value notified to the TX100 can be used for foreign object detection processing by the power loss method. The processing in the calibration phase is similar to the processing in S414 of FIG. 4, and therefore will not be described.

[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 TX100 controls the TX100 to transmit power to a plurality of RXs mounted on the TX100 in a time-division manner. Hereinafter, detailed operations in the power transfer phase will be described 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 similar to S501 to S504 in FIG. 5, and therefore the description 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 a change in the power transmission / reception state (e.g., a state change on the TX 100) in the power transmission range of the TX 100 (S706). For example, the foreign object detection unit 303 detects a foreign object by the power loss method described above using the calibration data of the target RX acquired in the calibration phase (S610 in FIG. 6). If a foreign object is detected, the process returns to S602 in FIG. 6 (processing after TX startup). On the other hand, the change in the power transmission / 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. Since 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, the process returns to the step after TX startup in the flow of Fig. 6, so that power is appropriately transmitted to all RXs even if, for example, the number of RXs placed on the TX100 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 designated by a predetermined counter) has ended. This counter is, for example, a counter that counts time, the number of intermittent power transmissions, or the number of packets or frames of communication. If the counter has ended in S707 (for example, if a predetermined condition / number is satisfied) (Yes in S707), the process returns to S702, and the TX100 selects another RX and transmits power.

[0085] If the predetermined counter has not finished in S707 (No in S707), the process proceeds to S708, and the control unit 101 judges whether or not the power transmission to the target RX has been completed. If the result of the judgment is, for example, that the target RX is not yet fully charged and the power transmission has not been completed, the process returns to S705, and the power transmission control unit 302 continues the power transmission. If it is judged that the power transmission to the target RX has been completed in S708, the process proceeds to S709, and the control unit 101 judges whether or not the power transmission to all RX has been completed. If the power transmission to all RX has not been completed, the process returns to S702, and the control unit 101 selects another RX to which the power transmission has not been completed, and the power transmission control unit 302 transmits power to the selected RX (target RX). If the power transmission to all RXs placed on the TX100 has been completed, the process proceeds to S710 and ends.

[0086] In this manner, in this embodiment, first, the TX100 sets a specific RX among the multiple RXs placed on the TX100 as a target RX, controls the non-target RXs so that they are not charged or powered by the TX100, and derives (acquires) calibration data for the target RX (FIG. 6). Then, the TX100 acquires calibration data for all RXs. After that, in the power transfer phase, the TX100 sets a specific RX among the multiple RXs placed on the TX100 as a target RX, controls the non-target RXs so that they are not charged or powered by the TX100, and transmits power to the target RX using the calibration data already derived (FIG. 7). This allows the TX100 to properly complete power transmission to all RXs by matching the state of each RX when the calibration data is derived with the state of each RX when power is transmitted.

[0087] In addition, 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 multiple RXs has been described. In the present embodiment, another control method for appropriately transmitting power to multiple RXs will be described. Below, differences from the first and second embodiments will be described, and descriptions of common parts will be omitted.

[0089] [Processing flow by power transmission device] 8 shows a flowchart of the process executed by the TX 100 in this embodiment. This process can be realized, for example, by the control unit 101 of the TX 100 executing a program read from the memory 106. Note that at least a 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 realizing each processing step.

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

[0091] When the non-target RX receives the message, it controls so that it is not charged or powered by the TX100 (for example, it cuts off the connection to the load (charging circuit, battery, etc.)). That is, the non-target RX controls the switch unit 209 (FIG. 2) to cut off the load (charging circuit, battery, etc.) and does not supply the received power to the load (charging circuit, battery, etc.).

[0092] Next, the TX100 transitions to a negotiation phase (S809) and transitions to a calibration phase (S810). 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 power transmission control unit 302 of the TX100 performs adjustments for efficient power transmission. The received power value notified to the TX100 can be used for foreign object detection processing by the power loss method. The processing in the calibration phase is similar to the processing in S414 of FIG. 4, and therefore will not be described.

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

[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 the power transmitting antennas is completed. If the switching of all the antennas is not 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 the antennas is completed, the process proceeds to S814 and ends.

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

[0096] When the TX100 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 a change in the power transmission and reception state (for example, a state change on the TX100) in the power transmission range of the TX100 (S706). For example, the foreign object detection unit 303 detects a foreign object by the above-mentioned power loss method using the calibration data of the target RX acquired in the calibration phase (S810 in FIG. 8). When a foreign object is detected, the process returns to the process of 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 TX100. Since the increase or decrease in the number of RXs on the TX100 also causes a change in the above-mentioned power loss, the foreign object detection unit 303 can detect an increase or decrease in the number of RXs on the TX100 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 appropriately transmitted to all RX 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 or not power transmission to the target RX is completed. If it is determined that power transmission is completed, for example, because the RX is fully charged, the process proceeds to S905 and is completed. If it is determined that power transmission is not completed, the process proceeds to S902, and the power transmission control unit 302 continues power transmission.

[0098] In this manner, in this embodiment, first, the TX100 sets a specific RX among the multiple RXs placed on the TX100 as a target RX, controls the non-target RXs so that they are not charged or powered by the TX100, and derives (acquires) calibration data for the target RX (FIG. 8). Then, the TX100 acquires calibration data for all RXs. After that, in the power transfer phase, the TX100 sets a specific RX among the multiple RXs placed on the TX100 as a target RX, controls the non-target RXs so that they are not charged or powered by the TX100, and transmits power to the target RX using the calibration data already derived (FIG. 9). This allows the TX100 to properly complete power transmission to all RXs by matching the state of each RX when the calibration data is derived with the state of each RX when power is transmitted.

[0099] The control method for appropriately transmitting power to multiple RXs has been described above with reference to three embodiments. In the above embodiments, a method for detecting a state change on a power transmitting device using a power loss method has been described as a foreign object detection function. However, since the Q value changes depending on an increase or decrease in the number of RXs on a TX, it is also possible to detect an increase or decrease in the number of RXs on a TX using a Q value measurement method. Therefore, in the Q value measurement method performed in the negotiation phase, when the TX detects a change in the power transmission and reception state (for example, a state change on the TX), the TX may be controlled to return to the operation after the TX is started. 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 value measurement method, the TX may be controlled to return to the operation after the TX was started when a change in the power transmission / reception state in the TX is detected based on the measurement results of the resonant frequency of the power transmitting antenna, the sharpness of the resonant curve, the inductor 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 section including the power transmitting antenna of the TX, or the measurement results of a photoelectric sensor, an eddy current type displacement sensor, a contact type displacement sensor, an ultrasonic sensor, an image discrimination sensor, a weight sensor, or the like mounted on the TX. In addition, the TX may periodically transmit an Analog Ping from a power transmitting antenna other than the power transmitting antenna 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 the operation after the TX was started. This is because in these cases, a new RX or a foreign object may be present in the vicinity of the power transmitting antenna.

[0101] In this way, the TX measures the power loss between TX and RX in a time-division manner for each of multiple RXs that are present within the TX's power transmission range when there is no foreign object between them, and transmits power to each of the individual RXs in a time-division manner, thereby making it possible to improve 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 a plurality of power transmitting antennas is connected to one power transmitting unit. However, a plurality of 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 has the first power transmitting antenna and the second power transmitting antenna, the first power transmitting antenna may be configured such that either the first power transmitting unit or the second power transmitting unit can be connected to the first power transmitting antenna. Here, consider a case in which the first power transmitting unit (power transmitting circuit) is connected to the first power transmitting antenna and power is 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). When 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, when 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) the 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 a 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 a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0104] The invention is not limited to the above-described embodiments, and various modifications and variations are possible 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)

Claims

1. A plurality of coils; A transmitting means for wirelessly transmitting a plurality of Pings; An acquisition means for acquiring identification information from one or more power receiving devices; A determination means for determining that there are a plurality of power receiving devices based on the acquired identification information; A selection means for selecting a coil corresponding to each of the plurality of power receiving devices when the plurality of power receiving devices is present; a power transmitting means for wirelessly transmitting power to a first power receiving device included in the plurality of power receiving devices via a first coil included in the plurality of coils and corresponding to the first power receiving device, and for wirelessly transmitting power to a second power receiving device included in the plurality of power receiving devices via a second coil included in the plurality of coils and corresponding to the second power receiving device, The power transmitting device, characterized in that 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.

2. The power transmitting device as described in Claim 1, characterized in that the Ping is a signal for starting the power receiving device.

3. The power transmission device as described in claim 1, characterized in that the Ping is a signal for detecting an object.

4. A method performed by a power transmission device having a plurality of coils, comprising: Send multiple Pings wirelessly, Obtaining identification information from one or more power receiving devices; determining that there are a plurality of power receiving devices based on the obtained identification information; When there are a plurality of power receiving devices, a coil corresponding to each of the plurality of power receiving devices is selected; wirelessly transmitting power to a first power receiving device included in the plurality of power receiving devices via a first coil included in the plurality of coils and corresponding to the first power receiving device; wirelessly transmitting power to a second power receiving device included in the plurality of power receiving devices via a second coil included in the plurality of coils and corresponding to the second power receiving device; 11. The method of claim 10, wherein during wireless power transmission to the first power receiving device via the first coil, a Ping is not transmitted via a coil in proximity to the first coil.

Images