Power receiving device and method

Abstract

To carry out a plurality of detection methods in state detection of a power transmitting antenna and a power receiving antenna and perform, depending on a measurement result, control for coping with positional displacement between the antennas and an object that may affect wireless power transmission.SOLUTION: In a wireless power transmission system, a power transmitting device 100 has a power transmitting antenna, and a power receiving device 200 has a power receiving antenna. The power transmitting device 100 and the power receiving device 200 measure a quality factor (such as a Q-factor) of the power transmitting antenna and an index (such as a coupling coefficient) representing an electromagnetic coupling state between the power transmitting antenna and the power receiving antenna. The power transmitting device 100 or the power receiving device 200 performs first or second control according to a measurement value of the quality factor and a measurement value of the index of the electromagnetic coupling state. The first control is control for coping with positional displacement between the power transmitting antenna and the power receiving antenna. The second control is control for coping with the presence of an object different from the power receiving device 200 between the power transmitting antenna and the power receiving antenna.SELECTED DRAWING: Figure 15

Description

[Technical Field]

[0001] The present disclosure relates to the technology of wireless power transmission. [Background technology]

[0002] In a wireless power transmission system that uses wireless power transmission technology, it is necessary to detect the presence or absence of an object (hereinafter sometimes referred to as a foreign object) different from the power receiving device between the power transmitting device and the power receiving device. Patent Document 1 discloses a method that can detect a metallic foreign object present near a coil without providing an additional sensor and can improve the detection accuracy. The electromagnetic coupling state between the power transmitting coil and the power receiving coil (hereinafter also simply referred to as the "coupling state") is detected by using changes in the coupling coefficient k and the resonance Q value of the power transmitting coil. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-115981 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional technology, when multiple state detection methods are feasible for wireless power transmission, there is no established method for appropriately controlling based on the detection results obtained by using multiple state detection methods in combination. The present disclosure aims to implement multiple detection methods for detecting the status of the transmitting antenna and the receiving antenna, and to perform control to deal with misalignment between the antennas and objects that may affect wireless power transmission based on the measurement results. [Means for solving the problem]

[0005] A power transmitting device according to an embodiment of the present disclosure includes a power transmitting means for transmitting power to a power receiving device via a power transmitting antenna, a measuring means for measuring a first index representing a quality factor or an attenuation state of the power transmitting antenna and a second index representing an electromagnetic coupling state between the power transmitting antenna and a power receiving antenna of the power receiving device, and a control means for acquiring the measurement results of the measuring means and controlling the power transmitting means. The control means compares the measured first and second indexes with respective thresholds, and performs a first control to address misalignment between the power transmitting antenna and the power receiving antenna if the measurement result of the first index satisfies a first condition that the index is within a first range and the measurement result of the second index does not satisfy a second condition that the index is within a second range, and performs a second control to address the presence of an object other than the power receiving device between the power transmitting antenna and the power receiving antenna if the measurement result of the first index does not satisfy the first condition and the measurement result of the second index does not satisfy the second condition. [Effects of the Invention]

[0006] According to the present disclosure, multiple detection methods are implemented to detect the status of the transmitting antenna and the receiving antenna, and control can be performed to deal with misalignment between the antennas and objects that may affect wireless power transmission based on the measurement results. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating a configuration example of a wireless power transmission system. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of a power transmitting device. [Figure 3] FIG. 2 illustrates an example of the configuration of a power receiving device. [Figure 4] FIG. 10 is an explanatory diagram of a threshold setting method for state detection using the Power Loss method. [Figure 5] FIG. 2 is a block diagram illustrating an example of a functional configuration of a control unit of the power transmitting device. [Figure 6] FIG. 10 is a sequence diagram illustrating an example of a process for wireless power transmission. [Figure 7]FIG. 10 is an explanatory diagram of state detection using a waveform decay method. [Figure 8] FIG. 10 is an explanatory diagram of a threshold setting method for state detection using the waveform decay method. [Figure 9] FIG. 10 is an explanatory diagram of a method for measuring the coupling state between a power transmitting antenna and a power receiving antenna. [Figure 10] FIG. 10 is an explanatory diagram of a threshold setting method for state detection using a bonding state measurement method. [Figure 11] FIG. 1 is an explanatory diagram of a Q-value measurement method. [Figure 12] FIG. 4 is a sequence diagram illustrating an example of operation in the first embodiment. [Figure 13] FIG. 10 is a sequence diagram illustrating another example of the operation in the first embodiment. [Figure 14] FIG. 10 is a sequence diagram illustrating yet another example of the operation in the first embodiment. [Figure 15] 4 is a flowchart illustrating processing of the power transmitting device in the first embodiment. [Figure 16] 5 is a flowchart illustrating processing of the power receiving device in the first embodiment. [Figure 17] FIG. 10 is a sequence diagram illustrating an example of operation in the second embodiment. [Figure 18] FIG. 10 is a sequence diagram illustrating another example of the operation in the second embodiment. [Figure 19] FIG. 10 is a sequence diagram illustrating yet another example of the operation in the second embodiment. [Figure 20] FIG. 10 is a sequence diagram illustrating yet another example of the operation in the second embodiment. [Figure 21] 10 is a flowchart illustrating processing of a power transmitting device according to a second embodiment. [Figure 22] 22 is a flowchart showing the processing following FIG. 21. [Figure 23] 10 is a flowchart illustrating processing of a power receiving device in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the embodiments, a wireless charging system to which a wireless power transmission system is applied is described. As an example, wireless power transmission based on the standard established by the Wireless Power Consortium (hereinafter referred to as the WPC standard) will be described.

[0009] [First embodiment] Fig. 1 is a diagram showing an example of the configuration of a wireless charging system. This system includes a power transmitting device 100, a power receiving device 200, and a charging stand 300. For simplicity of notation, the power receiving device 200 may be referred to as RX and the power transmitting device 100 as TX below. The detailed configurations of TX and RX will be described later using Figs. 2 and 3.

[0010] RX is an electronic device that receives power from TX and charges its built-in battery while placed on the charging stand 300. TX is an electronic device that transmits power wirelessly to RX placed on the charging stand 300. Since the charging stand 300 constitutes part of TX, hereinafter, when RX is "placed on the charging stand 300," it may be said that RX is "placed on TX." The spatial range in which RX can receive power from TX is schematically shown by the range of a dotted line frame 400 in FIG. 1.

[0011] The RX and TX may have a function to execute applications other than the wireless charging function. For example, the RX is a smartphone, and the TX is an accessory device for charging the battery of the smartphone. However, without being limited to this example, the RX and TX may be a tablet device, 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 RX and TX may also be an imaging device such as a still camera or a video camera, an automobile, a robot, a medical device, a printer, etc.

[0012] Next, a configuration example of the power transmitting device 100 will be described with reference to Fig. 2. Fig. 2 is a functional block diagram showing a configuration example of the power transmitting device 100 (TX). The TX has a control unit 101, a power supply unit 102, a power transmitting unit 103, a first communication unit 104, a power transmitting antenna 105, a memory 106, a resonant capacitor 107, a switch unit 108, and a second communication unit 109. Although Fig. 2 shows each functional block element as a separate entity, any number of functional block elements may be implemented within the same chip.

[0013] The control unit 101 controls the entire TX by executing a control program stored in the memory 106. The control unit 101 also controls power transmission, including communication for device authentication in the TX. The control unit 101 can 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). Alternatively, the control unit 101 may be configured with hardware, such as an ASIC (Application Specific Integrated Circuit). The control unit 101 may also include an array circuit, such as an FPGA (Field Programmable Gate Array), compiled to execute predetermined processes. The control unit 101 can store information to be stored during the execution of various processes in the memory 106 and can perform timing processing using a timer (not shown).

[0014] The power supply unit 102 supplies power to each functional block element. The power supply unit 102 includes, for example, a power supply connection circuit to a commercial power source and a battery. The battery is charged with power supplied from the commercial power source.

[0015] The power transmitting unit 103 converts DC or AC power input from the power supply unit 102 into AC power in a frequency band used for wireless power transmission, and inputs the AC power to the power transmitting antenna 105, thereby generating electromagnetic waves for receiving power at the RX. For example, the power transmitting unit 103 includes an inverter, and 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. The power transmitting unit 103 includes multiple FETs (Field Effect Transistors) that form a bridge, and a gate driver that controls the ON / OFF of the multiple FETs.

[0016] 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 antenna 105. The strength of the electromagnetic waves is controlled by the magnitude of the power transmission voltage or power transmission current. The control unit 101 controls the start or stop of power transmission and the intensity of the electromagnetic waves to be output by issuing instructions to the power transmitting unit 103. Based on an instruction signal from the control unit 101, the power transmitting unit 103 controls the output of AC frequency power so that power transmission by the power transmitting antenna 105 is started or stopped or the intensity of the electromagnetic waves to be output is controlled. Furthermore, the power transmitting unit 103 is assumed to have a power supply capacity sufficient to output 15 watts (W) of power to a charging unit (206 in Figure 3) of the power receiving device 200 (RX) that complies with the WPC standard.

[0017] The first communication unit 104 is connected to the control unit 101 and the power transmitting unit 103, and performs communication with the RX for power transmission control based on the WPC standard. The first communication unit 104 performs frequency shift keying on the electromagnetic waves output from the power transmitting antenna 105 and transmits information to the RX to perform communication. The first communication unit 104 also demodulates the electromagnetic waves modulated by the RX and transmitted from the power transmitting antenna 105 to acquire the information transmitted by the RX. Communication by the first communication unit 104 is performed by superimposing a communication signal on the electromagnetic waves transmitted from the power transmitting antenna 105.

[0018] The memory 106 can store information about the TX and RX states in addition to storing the control program. Information about the TX and RX states includes the transmitted power value, the received power value, etc. The information about the TX state is acquired by the control unit 101. Information about the RX state is acquired by the RX control unit (201 in FIG. 3) and can be received by the first communication unit 104.

[0019] The switch unit 108 is connected in parallel to the series circuit of the resonant capacitor 107 and the power transmitting antenna 105. The control unit 101 sends a control signal to the switch unit 108 to control its ON / OFF. The power transmitting antenna 105 is connected to the resonant capacitor 107. When the control signal from the control unit 101 turns the switch unit 108 to the ON state and short-circuits it, the power transmitting antenna 105 and the resonant capacitor 107 form a series resonant circuit and resonate at a specific frequency f1. At this time, a current flows through the closed circuit formed by the power transmitting antenna 105, the resonant capacitor 107, and the switch unit 108. On the other hand, when the control signal from the control unit 101 turns the switch unit 108 to the OFF state and the circuit is opened, power is supplied from the power transmitting unit 103 to the power transmitting antenna 105 and the resonant capacitor 107.

[0020] The second communication unit 109 is connected to the control unit 101, and communicates with the RX using a standard different from the WPC standard. For example, the second communication unit 109 communicates with the RX (the second communication unit 212 in FIG. 3) using an antenna different from the power transmitting antenna 105. Examples of standards include wireless LAN (Local Area Network), Bluetooth (registered trademark) Low Energy (BLE), and NFC (Near Field Communication).

[0021] Regarding communication between TX and RX, TX may selectively use one of multiple communication standards to communicate with RX. The following communication formats are available: Communication based on the first standard (WPC standard) is performed between the first communication unit 104 of the TX and the first communication unit 204 of the RX (FIG. 3). Communication based on a second standard (a standard other than the WPC standard) that is performed between the second communication unit 109 of the TX and the second communication unit 212 of the RX (FIG. 3).

[0022] Next, a configuration example of the power receiving device 200 will be described with reference to Fig. 3. Fig. 3 is a block diagram showing a configuration example of the power receiving device 200 (RX). The RX has a control unit 201, a user interface (hereinafter referred to as UI) unit 202, a power receiving unit 203, a first communication unit 204, a power receiving antenna 205, a charging unit 206, a battery 207, and a memory 208. The RX further has a first switch unit 209, a second switch unit 210, a resonant capacitor 211, a second communication unit 212, and a third switch unit 213. Note that the multiple functional block elements shown in Fig. 3 may be realized as one hardware module.

[0023] The control unit 201 controls each functional block element of the RX by executing a control program stored in the memory 208. Furthermore, the control unit 201 can perform control for executing applications other than wireless power transmission. The control unit 201 includes one or more processors such as a CPU or an MPU. The control unit 201 can also control the entire RX (e.g., the entire smartphone) in cooperation with an operating system (OS) running on it. Alternatively, the control unit 201 can be configured with hardware such as an ASIC, or can include an array circuit such as an FPGA compiled to execute predetermined processes. The control unit 201 stores information to be stored during the execution of various processes in the memory 208, and can also perform timing processing using a timer (not shown).

[0024] The UI unit 202 is connected to the control unit 201 and performs various outputs to the user. The various outputs include screen display, blinking or color changes of LEDs (Light Emitting Diodes), audio output from a speaker, vibration of the RX main unit, etc. The UI unit 202 is realized by a liquid crystal panel, a speaker, a vibration motor, etc.

[0025] The power receiving unit 203 acquires, via the power receiving antenna 205, AC power (AC voltage and AC current) generated by electromagnetic induction based on electromagnetic waves radiated from the power transmitting antenna 105 of the TX. 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. The charging unit 206 charges the battery 207. The power receiving unit 203 includes a rectifier and a voltage control unit required for supplying power to the load in the RX. The power receiving unit 203 supplies power for charging the battery 207 from the charging unit 206. It is assumed that the power receiving unit 203 has a power supply capacity sufficient to output 15 watts of power to the charging unit 206.

[0026] The first communication unit 204 communicates with the first communication unit 104 of the TX for power reception control based on the WPC standard. The first communication unit 204 is connected to the power receiving antenna 205 and the control unit 201. The first communication unit 204 demodulates the electromagnetic waves input from the power receiving antenna 205 to acquire information transmitted from the TX. The first communication unit 204 performs load modulation or amplitude modulation of the input electromagnetic waves and superimposes a signal related to information to be transmitted to the TX on the electromagnetic waves, thereby communicating with the TX.

[0027] The memory 208 stores control programs and also stores information about the states of the TX and RX. Information about the state of the RX is acquired by the control unit 201. Information about the state of the TX is acquired by the TX control unit 101 and can be received by the first communication unit 204 or the second communication unit 212.

[0028] First switch unit 209 is provided between charging unit 206 and battery 207, and is controlled by control unit 201. First switch unit 209 has a function of controlling whether or not power received by power receiving unit 203 is supplied to battery 207, and a function of controlling the load value. When first switch unit 209 is turned OFF and opened by control unit 201, the power received by power receiving unit 203 is not supplied to battery 207. When first switch unit 209 is turned ON and short-circuited by control unit 201, the power received by power receiving unit 203 is supplied to battery 207.

[0029] 3, first switch unit 209 is arranged between charging unit 206 and battery 207, but first switch unit 209 may be arranged between power receiving unit 203 and charging unit 206. Alternatively, first switch unit 209 may be arranged between power receiving unit 203 and a closed circuit formed by power receiving antenna 205, resonant capacitor 211, and second switch unit 210. In this case, first switch unit 209 has a function of controlling whether or not power received by power receiving unit 203 is supplied to power receiving unit 203.

[0030] 3, first switch unit 209 is illustrated as one functional block element, but first switch unit 209 can be realized as part of charging unit 206 or power receiving unit 203. Furthermore, first switch unit 209 is not limited to being inserted in series between charging unit 206 and battery 207, and first switch unit 209 may be inserted in parallel between charging unit 206 and battery 207. In this case, when first switch unit 209 is turned OFF by control unit 201 to open the circuit, the power received by power receiving unit 203 is supplied to battery 207. When first switch unit 209 is turned ON by control unit 201 to short-circuit the circuit, the power received by power receiving unit 203 is not supplied to battery 207.

[0031] On the input side of the power receiving unit 203, the second switch unit 210 is connected in parallel to the resonant capacitor 211. The resonant capacitor 211 is connected to the power receiving antenna 205 via the third switch unit 213. The second switch unit 210 and the third switch unit 213 are controlled by the control unit 201. The third switch unit 213 has a function of controlling whether or not the terminal of the power receiving antenna 205 is opened. When the control unit 201 turns the third switch unit 213 to the OFF state, the terminal of the power receiving antenna 205 is opened. When the control unit 201 turns the third switch unit 213 to the ON state, the power receiving antenna 205 is connected to the power receiving unit 203 via the resonant capacitor 211.

[0032] When the control unit 201 turns the third switch unit 213 ON and the second switch unit 210 ON, creating a short circuit, the power receiving antenna 205 and the resonant capacitor 211 form a series resonant circuit that resonates at a specific frequency f2. Current flows through the closed circuit formed by the power receiving antenna 205, the resonant capacitor 211, and the second switch unit 210, but not through the power receiving unit 203. When the second switch unit 210 turns OFF and opens the circuit, power received by the power receiving antenna 205 and the resonant capacitor 211 is supplied to the power receiving unit 203. Note that this is not limited to the example of FIG. 3 , and the second switch unit 210 may be disposed between the power receiving antenna 205 and the resonant capacitor 211. When the third switch unit 213 is ON and the second switch unit 210 is ON, the terminals of the power receiving antenna 205 are short-circuited. The third switch unit 213 may also be disposed between the resonant capacitor 211 and the power receiving unit 203.

[0033] In this system, the TX and RX perform wireless power transmission between the power transmitting antenna 105 and the power receiving antenna 205 based on the WPC standard. In the WPC standard, the amount of power guaranteed when the power receiving device 200 receives power from the power transmitting device 100 is specified by a value called guaranteed power (hereinafter referred to as "GP"). For example, GP indicates a power value that is guaranteed to be output to a load of the power receiving device 200 even if the power transmission efficiency between the power receiving antenna 205 and the power transmitting antenna 105 decreases due to a change in the positional relationship between the power receiving device 200 and the power transmitting device 100. The load of the power receiving device 200 is the charging unit 206, the battery 207, etc. shown in FIG. 3, and the value of GP corresponds to the amount of power guaranteed to be output from the power receiving unit 203. For example, assume that the GP is 5 (watts) and the positional relationship between the power receiving antenna 205 and the power transmitting antenna 105 changes. In this case, even if the power transmission efficiency is reduced, the power transmitting device 100 performs power transmission control so as to be able to output 5 watts to the load of the power receiving device 200. The GP is determined by negotiation between the power transmitting device 100 and the power receiving device 200. Note that this embodiment is applicable not only to the GP but also to a configuration in which power is transmitted and received at a power determined by mutual negotiation between the power transmitting device and the power receiving device.

[0034] Also, assume that an object is present near the power transmitting device 100 when power is transmitted from the power transmitting device 100 to the power receiving device 200. In this case, the object is an object (foreign object) that may affect power transmission from the power transmitting device 100 to the power receiving device 200, but is different from the power receiving device 200. Electromagnetic waves for power transmission may affect the foreign object, causing the foreign object to heat up or be destroyed. In the present disclosure, the foreign object is, for example, a paper clip or an IC card. Of the power receiving device and the product incorporating the power receiving device, or the power transmitting device and the object that are an integral part of the product incorporating the power transmitting device, objects that may unintentionally generate heat when exposed to wireless power transmitted by the power transmitting antenna are not considered foreign objects.

[0035] The WPC standard specifies a method for preventing a temperature rise or destruction of a foreign object by stopping power transmission when the foreign object is present. Specifically, the power transmitting device 100 is capable of detecting the presence of a foreign object on the charging stand 300. The power loss method is a method for detecting a foreign object based on the difference between the transmitted power in the power transmitting device 100 and the received power in the power receiving device 200. The Q-factor measurement method is a method for detecting a foreign object based on a change in the quality factor (Q-factor) of the power transmitting antenna 105 (power transmitting coil) in the power transmitting device 100. However, the foreign object detected by the power transmitting device 100 in this embodiment is not limited to an object present on the charging stand 300. The power transmitting device 100 is capable of detecting a foreign object located near the power transmitting device 100. For example, the power transmitting device 100 can detect a foreign object located within a range where power can be transmitted.

[0036] With reference to Figure 4, foreign object detection based on the power loss method defined in the WPC standard will be described. In Figure 4, the horizontal axis represents the transmitted power of power transmitting device 100, and the vertical axis represents the received power of power receiving device 200. On the graph line represented by straight line segment 1002, point 1000 corresponds to first transmitted power value Pt1 and first received power value Pr1, and point 1001 corresponds to second transmitted power value Pt2 and second received power value Pr2. On the graph line, point 1003 corresponds to third transmitted power value Pt3 and third received power value Pr3. The foreign object to be detected is a conductive metal piece or the like.

[0037] First, the power transmitting device 100 transmits power to the power receiving device 200 at a first transmission power value Pt1, and the power receiving device 200 receives power at a first reception power value Pr1. Hereinafter, this state will be referred to as a light load state. The power transmitting device 100 then stores the first transmission power value Pt1. Herein, the first transmission power value Pt1 and the first reception power value Pr1 are predetermined minimum transmission power values ​​and reception power values. At this time, the power receiving device 200 performs load control so that the received power is minimized. For example, the power receiving device 200 may disconnect the load from the power receiving antenna 205 so that the received power is not supplied to the load (such as the charging unit 206 or battery 207 in FIG. 3). This can be achieved by controlling the first switch unit 209 described above. Next, the power receiving device 200 notifies the power transmitting device 100 of the first reception power value Pr1. The power transmitting device 100 receives a signal related to the first received power value Pr1 from the power receiving device 200 and calculates the power loss between the power transmitting device 100 and the power receiving device 200. The power loss at this time is Pt1-Pr1 (=Ploss1). A calibration point (hereinafter abbreviated as CP) 1000 indicating the correspondence between Pt1 and Pr1 can be created.

[0038] Next, the power transmitting device 100 changes the transmission power value to a second transmission power value Pt2 and transmits power to the power receiving device 200, and the power receiving device 200 receives power at the second received power value Pr2. Hereinafter, this state is referred to as a connected load state. The power transmitting device 100 then stores the second transmission power value Pt2. Herein, the second transmission power value Pt2 and the second received power value Pr2 are predetermined maximum transmission power values ​​and received power values. At this time, the power receiving device 200 performs load control so that the received power is maximized. For example, the power receiving device 200 connects the power receiving antenna 205 to the load so that the received power is supplied to the load. This can be achieved by controlling the first switch unit 209 described above. Next, the power receiving device 200 notifies the power transmitting device 100 of the second received power value Pr2. The power transmitting device 100, which has received a signal relating to the second received power value Pr2 from the power receiving device 200, calculates the power loss between the power transmitting device 100 and the power receiving device 200. The power loss at this time is Pt2-Pr2 (=Ploss2). A CP1001 indicating the correspondence between Pt2 and Pr2 can be generated.

[0039] The power transmitting device 100 performs linear interpolation between CP1000 and CP1001 to generate a line segment 1002. The line segment 1002 represents the relationship between the transmitted power and the received power in a state where it is detected that no foreign object is present near the power transmitting device 100 and the power receiving device 200 (hereinafter referred to as a first detection state). Based on the line segment 1002, the power transmitting device 100 can estimate the power value that the power receiving device 200 will receive when transmitting power at a predetermined transmitted power in the first detection state. For example, assume that the power transmitting device 100 transmits power at a third transmitted power value Pt3. In this case, the power transmitting device 100 can estimate a third received power value Pr3 that the power receiving device 200 will receive from a point 1003 on the line segment 1002 that corresponds to Pt3. As described above, the power loss between the power transmitting device 100 and the power receiving device 200 corresponding to the load can be determined based on multiple combinations of the transmitted power value of the power transmitting device 100 and the received power value of the power receiving device 200 measured while changing the load. Furthermore, the power loss between the power transmitting device 100 and the power receiving device 200 corresponding to all loads can be estimated by interpolating multiple combinations of the transmitted power value and the received power value. The calibration process performed by the power transmitting device 100 and the power receiving device 200 in this manner to obtain combinations of the transmitted power value and the received power value by the power transmitting device 100 is called "calibration process of the power loss method." The calibration process is also abbreviated as CAL process.

[0040] After the CAL process of the Power Loss method, the power transmitting device 100 actually transmits power to the power receiving device 200 at the third transmission power value Pt3, and the power transmitting device 100 receives power at the received power value Pr3 from the power receiving device 200. * It is assumed that the power transmitting device 100 receives a signal regarding the received power value Pr3 actually received from the power receiving device 200 from the received power value Pr3 in the first detection state. * Subtract Pr3-Pr3 * (=Ploss_FO) is calculated. When a foreign object is present near the power transmitting device 100 and the power receiving device 200, Ploss_FO can be estimated as the power consumed by the foreign object, that is, the power loss. Hereinafter, the state in which it is detected that a foreign object is present near the power transmitting device 100 and the power receiving device 200 is referred to as a second detection state.

[0041] In the second detection state, the power transmitting device 100 compares the power loss Ploss_FO that is likely to be consumed by the foreign object with a predetermined threshold. If the value of the power loss Ploss_FO exceeds the threshold, the power transmitting device 100 can determine that a foreign object is present. Alternatively, the power transmitting device 100 acquires a third received power value Pr3 in the first detection state from the power receiving device 200, and calculates in advance the power loss Pt3-Pr3 (=Ploss3) between the power transmitting device 100 and the power receiving device 200. Next, the power transmitting device 100 acquires the received power value Pr3 from the power receiving device 200 in the second detection state. *and obtains the power loss Pt3-Pr3 between the power transmitting device 100 and the power receiving device 200 in the second detection state. * (=Ploss3 * Then, the power transmitting device 100 calculates Ploss3 * The power loss Ploss_FO can be estimated using -Ploss3.

[0042] As described above, there are two methods for calculating Ploss_FO in the second detection state. Pr3-Pr3 * The first method calculates Ploss_FO from Ploss3 * - The second method for calculating Ploss_FO from Ploss3. In this embodiment, the second method will basically be described, but the contents of this embodiment can also be applied to the first method.

[0043] In this embodiment, the RX and TX 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. In each phase, communication for power transmission and reception control is performed. For example, foreign object detection using the power loss method is performed in the power transfer phase based on data obtained in the calibration phase. Furthermore, foreign object detection using the Q-value measurement method is performed before power transmission (before sending a digital ping and in the negotiation or renegotiation phase).

[0044] The WPC standard defines the phases before power transmission as Selection phase, Ping phase, Identification and Configuration phase (Configuration phase), Negotiation phase, and Calibration phase. Hereinafter, the Identification and Configuration phase (Configuration phase) will be referred to as the I&C phase. The processing in each phase will be explained below.

[0045] In the Selection phase, the TX intermittently transmits Analog Pings to detect that an object has been placed on the charging base of the TX. For example, it detects that the RX, a conductor piece, or the like has been placed on the charging base. The TX detects either the voltage value or the current value, or both, of the power transmitting antenna 105 when the Analog Ping is transmitted. If the voltage value is below a threshold or if the current value exceeds a threshold, the TX determines that an object is present and transitions to the Ping phase.

[0046] In the Ping phase, the TX transmits a Digital Ping with higher power than the Analog Ping. The power of the Digital Ping is sufficient to start the control unit of the RX placed on the TX. The RX notifies the TX of the received voltage value. In this way, the TX recognizes that the object detected in the Selection phase is the RX by receiving a response from the RX that received the Digital Ping. When the TX is notified of the received voltage value, it transitions to the I&C phase. Furthermore, before transmitting the Digital Ping, the TX measures the Q-factor of the power transmitting antenna 105, for example, using an Analog Ping. This measurement result is used when performing foreign object detection processing using the Q-factor measurement method.

[0047] In the I&C phase, TX identifies RX and obtains device configuration information (capability information) from RX. RX transmits an ID Data packet and a Configuration Data packet. The ID Data packet contains the RX's identifier information, and the Configuration Data packet contains the RX's device configuration information (capability information). Upon receiving the ID Data packet and Configuration Data packet signals, TX responds with an acknowledgement (positive response ACK). Then the I&C phase ends.

[0048] In the negotiation phase, the GP value is determined based on the GP value requested by the receiver and the transmitter's power transmission capability. The transmitter also receives an FOD Status Data packet from the receiver, which includes a Reference Quality Factor Value and a Reference Resonance Frequency Value. The Reference Quality Factor Value is the Q-factor that can be measured at the terminals of the transmitter's power transmitting antenna when the receiver is placed on the test transmitter and there are no foreign objects nearby. The Reference Resonance Frequency Value is the resonance frequency that can be measured at the terminals of the transmitter's power transmitting antenna when the receiver is placed on the test transmitter and there are no foreign objects nearby. The Q-factor measurement method determines the presence or absence of a foreign object based on thresholds based on the Reference Quality Factor Value and Reference Resonance Frequency Value. The transmitter performs foreign object detection using the Q-factor measurement method in response to a request from the receiver. The WPC standard also specifies a method of transitioning to the power transfer phase, and then performing the same processing as the negotiation phase again at the receiver's request. The phase in which these processing is performed after the power transfer phase is called the renegotiation phase.

[0049] In the calibration phase, CAL processing is performed based on the WPC standard. RX also notifies TX of a predetermined received power value, and TX adjusts the power transmission so that it can transmit power efficiently. The predetermined received power value is, for example, the received power value in a light load state (light load state) or a maximum load state (connected load state). The received power value notified to TX is used for foreign object detection processing using the power loss method.

[0050] In the power transfer phase, the TX and RX perform control for starting and continuing power transmission, as well as error processing and stopping power transmission due to full charge. The TX and RX perform communication processing for this power transmission and reception control. For example, using the power transmitting antenna 105 and power receiving antenna 205 used when performing wireless power transmission based on the WPC standard, communication is performed by superimposing a signal on the electromagnetic waves transmitted from the power transmitting antenna 105 or power receiving antenna 205. Note that the range in which communication based on the WPC standard between the TX and RX is possible is the same as the range in which the TX can transmit power.

[0051] Next, the function of the control unit 101 of the TX will be described with reference to Fig. 5. Fig. 5 is a block diagram showing an example of the functional configuration of the control unit 101 of the power transmitting device 100 (TX). The control unit 101 has a communication control unit 301, a power transmission control unit 302, a measurement unit 303, a setting unit 304, and a state detection unit 305. The communication control unit 301 controls communication with the RX based on the WPC standard via the first communication unit 104, or controls communication with the RX via the second communication unit 109.

[0052] The power transmission control unit 302 controls the power transmission unit 103 to control power transmission to RX. The measurement unit 303 measures a waveform attenuation index, which will be described later. The measurement unit 303 also measures the power transmitted to RX via the power transmission unit 103, and measures the average transmitted power per unit time. The measurement unit 303 also measures the Q-factor of the power transmitting antenna 105. The state detection unit 305 measures a quantity (e.g., coupling coefficient) that represents the electromagnetic coupling state between the power transmitting antenna 105 and the power receiving antenna 205.

[0053] The setting unit 304 calculates and sets a threshold value for detecting a foreign object based on the waveform attenuation index measured by the measurement unit 303. The setting unit 304 also calculates and sets a threshold value for detecting a foreign object or a threshold value for detecting a positional deviation between TX and RX based on, for example, the coupling coefficient between the power transmitting antenna 105 and the power receiving antenna 205 measured by the measurement unit 303.

[0054] The state detection unit 305 detects the states of the TX and RX. For example, the state detection unit 305 detects a foreign object between the TX and RX, and also detects a misalignment between the power transmitting antenna 105 and the power receiving antenna 205. More specifically, the state detection unit 305 can perform state detection processing using a power loss method, a Q-factor measurement method, a waveform attenuation method, and the electromagnetic coupling state (e.g., coupling coefficient) between the power transmitting antenna 105 and the power receiving antenna 205. The state detection unit 305 can also perform foreign object detection and positional misalignment detection processing between the power transmitting antenna 105 and the power receiving antenna 205 using other methods. For example, in a TX equipped with an NFC communication function, the state detection unit 305 performs state detection processing using an opposite device detection function according to the NFC standard. In addition to detecting the presence or absence of a foreign object and the electromagnetic coupling state between the power transmitting antenna and the power receiving antenna, the state detection unit 305 can also detect state changes on the TX. For example, the TX can detect an increase or decrease in the number of power receiving devices 200 on the TX.

[0055] The setting unit 304 sets a threshold value that serves as a reference for determining the presence or absence of a foreign object when the TX performs status detection. Status detection may be, for example, status detection based on a power loss method, a Q-factor measurement method, or a waveform attenuation method, or status detection based on the coupling coefficient between the power transmitting antenna 105 and the power receiving antenna 205. The setting unit 304 can also set a determination threshold value required for status detection processing using other methods. The status detection unit 305 can perform foreign object detection processing and positional deviation detection processing between the power transmitting antenna 105 and the power receiving antenna 205 based on the threshold value set by the setting unit 304 and the measurement results by the measurement unit 303. For example, the status detection unit 305 can acquire data such as a waveform attenuation index, transmission power, Q-factor, and coupling coefficient between the power transmitting antenna 105 and the power receiving antenna 205 as the measurement results of the measurement unit 303.

[0056] 5 can be realized using a program executed by a CPU or the like included in the control unit 101. Each process is executed in parallel according to an independent program while maintaining synchronization between the programs by event processing or the like. However, two or more of these processes may be incorporated into the processing of a single program.

[0057] The flow of processing for wireless power transmission according to the WPC standard will be described with reference to Fig. 6. Fig. 6 is a sequence diagram illustrating an example of the operation of the power transmitting device 100 and the power receiving device 200 in multiple phases. In Fig. 6, the left side shows the operation of the power transmitting device 100 (TX), and the right side shows the operation of the power receiving device 200 (RX). RX is an electronic device such as a communication device or an imaging device, and an example of the charging operation of its battery is shown. F501 to F528 in the diagram are symbols and numbers for distinguishing the operation at each stage in chronological order, with larger numbers indicating later operations.

[0058] In F501, TX repeatedly transmits Analog Ping according to the WPC standard intermittently to detect objects within the power transmission range. TX executes the processes specified as the Selection phase and Ping phase, and waits for RX to be placed on it.

[0059] At F502, the user of the electronic device brings the RX close to the TX to charge the battery. For example, the user places the RX on the TX, thereby bringing the RX closer to the TX. At F503, an Analog Ping is transmitted after the RX is placed on the TX. At F504, the TX detects the presence of an object within the power transmission range. In this case, at F505, the TX transmits a Digital Ping conforming to the WPC standard. At F506, when the RX receives the Digital Ping, it can determine that the TX has detected the RX. Furthermore, when a predetermined response to the Digital Ping is received, the TX determines that the detected object is the RX and that the RX has been placed on the charging stand 300.

[0060] After detecting the placement of the RX, in F507 the TX acquires the identification information and capability information from the RX through communication in the I&C phase. For example, the RX identification information includes the Manufacturer Code and Basic Device ID. An example of the RX capability information is shown below. -Information that allows you to identify the version of the WPC standard that the RX supports. · Maximum Power Value or Reference Power, which is a value that specifies the maximum power that the RX can supply to the load. -Information indicating whether the RX has the WPC standard negotiation function.

[0061] The TX may obtain the identification information and capability information of the RX by a method other than the I&C phase communication of the WPC standard. The identification information of the RX may be any other identification information that can identify an individual RX, such as a Wireless Power ID.

[0062] Next, in F508, the TX determines a GP value with the RX through communication in the negotiation phase defined by the WPC standard. Alternatively, in F508, other processing for determining the GP value may be performed, not limited to communication in the negotiation phase of the WPC standard. Furthermore, if the TX acquires, for example, in F507, information indicating that the RX does not support the negotiation phase, the TX does not perform communication in the negotiation phase and determines the GP value to a predetermined value. The predetermined value is, for example, a value defined in advance in the WPC standard. In this embodiment, the GP value in F508 is set to 5 (watts).

[0063] Next, in the calibration phase defined in the WPC standard, the TX performs CAL processing of the Power Loss method based on the determined GP value. First, in F509, the RX transmits a signal containing information about the received power in a light load state (hereinafter referred to as first reference received power information) to the TX. A light load state is, for example, a load disconnection state or a load state in which the transmitted power value is equal to or less than a first threshold. For example, the first reference received power information is the received power information of the RX when the transmitted power of the TX is 500 milliwatts. The first reference received power information is information included in the Received Power Data packet (mode 1) defined in the WPC standard, but other messages may also be used. The TX determines whether to accept the first reference received power information based on the power transmission state of its own device. If the TX accepts the first reference received power information, it transmits an ACK, which is a positive response, to the RX. If the TX does not accept the first reference received power information, it transmits a NAK, which is a negative response, to the RX.

[0064] In F510, RX receives an ACK from TX. RX performs processing to transmit to TX a signal containing information about the received power in a load-connected state (hereinafter referred to as second reference received power information). The load-connected state is, for example, a maximum load state or a load state in which the transmitted power value is equal to or greater than a second threshold. In this embodiment, since the GP value in F508 is 5, the second reference received power information is the received power information of RX when the transmitted power of TX is 5 watts. Alternatively, it is the received power information of RX when the transmitted power of TX is close to the above-mentioned Reference Power value. Here, the second reference received power information is information contained in the Received Power Data packet (mode 2) specified in the WPC standard, but other messages may also be used. In F511, RX transmits to TX a transmitted power output change request containing a positive designated value, as indicated by the plus sign, to increase the transmitted power from TX to 5 watts.

[0065] TX receives a request to change the transmitting power output from RX, and if it is possible to increase the transmitting power, it changes the transmitting power output in F512 and performs processing to increase the transmitting power. In F513, TX returns an acknowledgment ACK to RX. In F514, RX sends TX a request to change the transmitting power output, including a positive specified value exceeding 5 watts. The second reference receiving power information is the receiving power information when the transmitting power of TX is 5 watts. Therefore, if TX receives a request from RX in F514 to increase the power by more than 5 watts, it returns a negative acknowledgment NAK to the transmitting power change request. In this case, the transmitting power output cannot be changed, and in F515 TX suppresses transmitting power above the specified level.

[0066] Upon receiving a NAK from TX, RX determines that the specified transmission power has been reached. In F516, RX transmits to TX a signal related to second reference received power information, which is information including the received power in a load-connected state.

[0067] In F517, the TX can calculate the amount of power loss between the TX and the RX in the light load state and the load-connected state based on the transmission power value of the TX and the received power value included in the first and second reference received power information. The TX can also calculate the amount of power loss between the TX and the RX for all possible transmission powers of the TX by performing interpolation between multiple power loss amounts. In this embodiment, all possible transmission powers of the TX are, for example, any power in the range from 500 milliwatts to 5 watts.

[0068] In F518, TX transmits an acknowledgement ACK to the second reference received power information from RX, and completes the CAL process. When TX determines that charging can be started, it starts power transmission to RX, and charging in RX starts.

[0069] In this embodiment, before starting the power transmission process, the TX and RX perform device authentication processing in F519. If the TX and RX determine that each other's devices can support a larger GP value, they perform GP value redetermining processing in F520. A value larger than the GP value set in F508 is redetermined as the GP value. For example, the G value redetermined in F520 is 15 (watts). In this case, in F521, the RX transmits a transmitting power output change request to the TX, including a positive designated value, to increase the TX's transmitting power to 15 watts. In F522, the TX returns an acknowledgment ACK to the transmitting power output change request. Then, in F523, the RX transmits a transmitting power output change request to the TX, including a positive designated value. If the TX receives a request from the RX to increase power by more than 15 watts in F524, the TX does not accept the transmitting power output change request and returns a negative acknowledgment NAK to the transmitting power output change request.

[0070] In this way, RX and TX continue to increase the transmission power output using ACK and NAK. Then, TX and RX perform CAL processing again for the re-determined GP = 15 (watts). Specifically, in F525, RX transmits a signal of information regarding the received power in the RX load-connected state when TX's transmission power is 15 watts (hereinafter referred to as third reference received power information). In F526, TX performs CAL processing based on the received power values ​​included in the first, second, and third reference received power information, and calculates the amount of power loss between TX and RX for all possible transmission powers for TX. In F527, TX transmits an ACK acknowledgement in response to the third reference received power information from RX, completing CAL processing. After that, in F528, TX determines that charging can be started, starts power transmission processing to RX, and transitions to the Power Transfer phase.

[0071] In the power transfer phase, TX transmits power to RX and performs foreign object detection processing using the power loss method. For example, by performing CAL processing, the amount of power loss between TX and RX in the first detection state during power transmission processing is calculated from the difference between the transmitted power value and the received power value. The calculated amount of power loss corresponds to the reference amount of power loss in a state where no foreign object is present. Then, if TX determines that the difference between the amount of power loss between TX and RX measured during power transmission after CAL processing and the reference amount of power loss is equal to or greater than a threshold, it determines that the state is the second detection state.

[0072] As described above, the power loss method is a method for detecting a foreign object based on the measurement results of the amount of power loss during power transmission from power transmitting device 100 to power receiving device 200. This method has the disadvantage that the accuracy of foreign object detection decreases when power transmitting device 100 is transmitting a large amount of power, but has the advantage that high power transmission efficiency can be maintained because foreign object detection processing can be performed while power transmission is continued.

[0073] However, foreign object detection using only the power loss method during the power transfer phase may result in erroneous foreign object detection or an erroneous determination that there is no foreign object even though there is one. For example, consider a case where a foreign object is present near the TX and RX during power transmission from the TX during the power transfer phase. In this case, there is a possibility that heat generation from the foreign object may increase, so it is necessary to improve the accuracy of foreign object detection during the power transfer phase. Therefore, with the aim of improving foreign object detection accuracy, we will explain the waveform attenuation method, which enables foreign object detection based on the attenuation state of the transmitted wave.

[0074] According to the waveform attenuation method, the power transmitting device 100 can detect a foreign object using a power transmission waveform (voltage waveform or current waveform) related to power transmission to the power receiving device 200. In other words, foreign object detection becomes possible without using a newly defined foreign object detection signal or the like.

[0075] FIG. 7 is a diagram illustrating the principle of foreign object detection using the waveform attenuation method. This figure shows an example of foreign object detection using a transmission waveform for power transmission from a power transmitting device 100 (TX) to a power receiving device 200 (RX). In FIG. 7, the horizontal axis represents time, and the vertical axis represents voltage or current. A waveform 600 shown in FIG. 7 shows, for example, the change over time in the voltage value of a high-frequency voltage applied to the power transmitting antenna 105 of the TX. The TX, which is transmitting power to the RX via the power transmitting antenna 105, stops transmitting power at time T0. At time T0, the power supply for power transmission from the power supply unit 102 is stopped. The frequency f of the transmission wave is a fixed frequency between 85 kHz and 205 kHz, for example, as used in the WPC standard. Point 601 on the waveform 600 is a point on the envelope of the high-frequency voltage and corresponds to a voltage value A1 at time T1. (T1, A1) at point 601 indicates that the voltage value at time T1 is A1. Point 602 on waveform 600 is a point on the envelope of the high frequency voltage, and corresponds to voltage value A2 at time T2. At point 602, (T2, A2) indicates that the voltage value at time T2 is A2.

[0076] The quality factor (Q-factor) of the power transmitting antenna 105 can be calculated based on the change in voltage value over time after time T0. For example, the TX calculates the Q-factor using Equation 1 based on the time, voltage value, and frequency f of the high-frequency voltage at points 601 and 602 on the envelope of the high-frequency voltage. Q=π·f·(T2-T1) / ln(A1 / A2) (Equation 1) In Equation 1, ln represents the natural logarithm function.

[0077] The Q-factor value decreases when a foreign object is present near the TX and RX. This is because the foreign object causes energy loss. Therefore, when focusing on the slope of the voltage attenuation, the slope of the line connecting points 601 and 602 is steeper when a foreign object is present than when no foreign object is present. When energy loss occurs due to a foreign object, the attenuation rate of the amplitude of waveform 600 increases. For example, in the waveform attenuation method, the presence or absence of a foreign object can be determined based on the attenuation state of the voltage value between points 601 and 602. The actual presence or absence of a foreign object can be determined by comparing some numerical value that represents the attenuation state. For example, when using the Q-factor for determination, a Q-factor value lower than the reference value means that the waveform attenuation rate (the degree of decrease in waveform amplitude per unit time) is high.

[0078] As another example, the determination can be made using the slope of the line connecting points 601 and 602, calculated as (A1-A2) / (T2-T1). If the times (T1 and T2) at which the voltage attenuation state is measured are fixed, the difference (A1-A2) in the voltage values ​​or the ratio (A1 / A2) of the voltage values ​​can be used to determine whether a foreign object is present. Alternatively, if the voltage value A1 immediately after power transmission is stopped is constant, the voltage value A2 after a predetermined time has elapsed can be used to determine whether a foreign object is present. Alternatively, the time (T2-T1) that elapses until the voltage value A1 reaches the predetermined voltage value A2 can be used to determine whether a foreign object is present.

[0079] The waveform attenuation method can determine the presence or absence of a foreign object based on the attenuation state of the waveform during a power transmission outage. Indicators such as the Q-factor that represent the attenuation state are collectively referred to as "waveform attenuation indexes" in this embodiment. While the vertical axis in FIG. 7 represents the voltage value of the high-frequency voltage applied to the TX power transmitting antenna 105 in the above description, the vertical axis in FIG. 7 may also represent the current value flowing through the power transmitting antenna 105. As with the voltage value, the attenuation state of the current value during a power transmission outage varies depending on the presence or absence of a foreign object. When a foreign object is present, the waveform attenuation rate is higher than when a foreign object is not present. Therefore, a foreign object can be detected by applying the same method described above to the temporal change in the current value flowing through the power transmitting antenna 105. That is, the presence or absence of a foreign object can be determined and foreign object detection can be performed using waveform attenuation indexes such as the Q-factor calculated from the current waveform, the slope of the attenuation of the current value, the difference between the current values, the ratio of the current values, the absolute value of the current values, or the time until the current value reaches a predetermined value.

[0080] There is also a method based on both the attenuation state of the voltage value and the attenuation state of the current value. With this method, the presence or absence of a foreign object can be determined using an evaluation value calculated from the waveform attenuation index of the voltage value and the waveform attenuation index of the current value. Note that the method is not limited to measuring the waveform attenuation index during a period when the TX temporarily stops transmitting power. The waveform attenuation index may also be measured during a period when the TX temporarily reduces the power supplied from the power supply unit 102 from a predetermined power level to a lower power level.

[0081] A specific example of a method for detecting foreign objects based on the transmission waveform (voltage waveform applied to the power transmitting antenna or current waveform flowing through the power transmitting antenna) using the waveform attenuation method will be described with reference to FIG. 7. The transmission waveform is not stable during the transient response period immediately after the start of power transmission by the TX. Therefore, during the transient response period, the RX controls the TX so that it does not communicate using load modulation or amplitude modulation. In addition, the TX controls the RX so that it does not communicate using frequency shift keying.

[0082] TX temporarily suspends power transmission to RX at the timing (time T0) when foreign object detection is performed. During the foreign object detection period when power transmission is temporarily suspended, the amplitude of the transmitted wave attenuates. TX calculates the waveform attenuation rate of the transmitted wave at this time. If the calculated waveform attenuation rate exceeds a predetermined threshold, TX determines that a foreign object is present. After the predetermined foreign object detection period has elapsed, if TX determines that no foreign object has been detected, TX resumes power transmission to RX. After power transmission resumes, TX repeatedly waits during the transient response period, determines the timing of foreign object detection, stops power transmission, and performs foreign object detection processing.

[0083] When measuring the waveform attenuation index, if elements such as power receiving unit 203, charging unit 206, and battery 207 are connected to power receiving antenna 205 and resonant capacitor 211 of power receiving device 200, the waveform attenuation index is affected by the loads of these elements. That is, the value of the waveform attenuation index changes depending on the states of power receiving unit 203, charging unit 206, and battery 207. As a result, even if the value of the waveform attenuation index is large, for example, it is difficult to distinguish whether this is due to the influence of a foreign object or a change in the state of power receiving unit 203, charging unit 206, battery 207, etc.

[0084] Therefore, when measuring the waveform attenuation index to detect a foreign object, the RX control unit 201 turns off the first switch unit 209. This makes it possible to suppress the influence of the battery 207. Alternatively, the control unit 201 turns on the second switch unit 210 to short-circuit it, causing a current to flow through the closed loop circuit formed by the power receiving antenna 205, the resonant capacitor 211, and the second switch unit 210. This makes it possible to suppress the influence of the power receiving unit 203, the charging unit 206, and the battery 207.

[0085] As described above, more accurate foreign object detection is possible by performing foreign object detection with first switch section 209 disconnected or with second switch section 210 turned on and short-circuited (connected). Alternatively, even more accurate foreign object detection is possible by both disconnecting first switch section 209 and short-circuiting (connecting) second switch section 210. Furthermore, the same effect can be obtained by setting first switch section 209 to a light load state instead of disconnecting it.

[0086] Furthermore, when measuring the waveform attenuation index, if elements such as the power transmitting unit 103, the first communication unit 104, and the power supply unit 102 are connected to the power transmitting antenna 105 and the resonant capacitor 107 of the power transmitting device 100, the waveform attenuation rate is affected by these elements. That is, the value of the waveform attenuation index changes depending on the states of the power transmitting unit 103, the first communication unit 104, and the power supply unit 102. As a result, even if the value of the waveform attenuation index is large, for example, it is difficult to distinguish whether this is due to the influence of a foreign object or the influence of the power transmitting unit 103, the first communication unit 104, and the power supply unit 102.

[0087] Therefore, when measuring the waveform attenuation index, the control unit 101 of the TX turns on the switch unit 108 to allow current to flow through the closed loop circuit formed by the power transmitting antenna 105, the resonant capacitor 107, and the switch unit 108. This makes it possible to suppress the influence of the power transmitting unit 103, the first communication unit 104, and the power supply unit 102. Alternatively, a switch may be provided between the power transmitting unit 103 and the closed loop circuit formed by the power transmitting antenna 105, the resonant capacitor 107, and the switch unit 108. When the TX measures the waveform attenuation index and detects a foreign object, it is possible to suppress the above-mentioned influence by controlling the switch to disconnect the closed loop circuit from the power transmitting unit.

[0088] As described above, more accurate foreign object detection is possible by setting switch unit 108 to a short-circuit (connection) state in which it is turned on, or by setting the closed loop circuit and power transmission unit 103 to a disconnection state in which the switch disconnects them. Alternatively, even more accurate foreign object detection is possible by both shorting switch unit 108 and disconnecting the switch.

[0089] Next, a method for setting a threshold value for the waveform attenuation index when detecting a state or foreign object using the waveform attenuation method will be described. In Fig. 8, the horizontal axis represents the transmitted power of power transmitting device 100, and the vertical axis represents the waveform attenuation index (waveform attenuation rate) of the voltage waveform or current waveform. On the graph line represented by straight line segment 1102, point 1100 corresponds to the transmitted power value Pt1 and waveform attenuation index δ1, and point 1101 corresponds to the transmitted power value Pt2 and waveform attenuation index δ2. On the graph line, point 1103 corresponds to the transmitted power value Pt3 and waveform attenuation index δ3.

[0090] First, RX controls itself so that it is in a light-load state when power is transmitted from TX. In a light-load state, either no power is supplied to the load of RX, or only power below a threshold is supplied. In this state, the transmission power value of TX is set to Pt1. Then, TX stops power transmission in the light-load state and measures the waveform attenuation index δ1. At this time, TX recognizes the transmission power value Pt1 and stores in memory CP1100, which is a calibration point that associates the transmission power value Pt1 with the waveform attenuation index δ1. Next, RX controls the load connection state. The load connection state is a state in which, when power is transmitted from TX, maximum power is supplied to the load of RX, or power above a predetermined threshold is supplied. In this state, TX sets the transmission power value of TX to Pt2. Then, TX stops power transmission in the load-connected state and measures the waveform attenuation index δ2. At this time, TX stores in memory CP1101, which associates the transmission power value Pt2 with the waveform attenuation index δ2. Next, the TX generates a line segment 1102 by linearly interpolating between CP1100 and CP1101. The line segment 1102 shows the relationship between the transmission power and the waveform attenuation index of the transmission wave in the first detection state, in which no foreign object is present around the TX and RX. Therefore, the TX can estimate the waveform attenuation index of the transmission wave for each transmission power value in the first detection state based on the line segment 1102. For example, for a transmission power value Pt3, the waveform attenuation index is estimated to be δ3 from point 1103 on the line segment 1102 corresponding to Pt3. Based on the estimation result, the TX can calculate a threshold value used to determine the presence or absence of a foreign object for each transmission power value. For example, a waveform attenuation index that is larger by a predetermined value (a value corresponding to the measurement error) than the estimated result of the waveform attenuation index in the first detection state for a certain transmission power value can be set as the threshold value for determining the presence or absence of a foreign object.

[0091] The CAL process performed by the power transmitting device 100 and the power receiving device 200 so that the power transmitting device 100 can obtain a combination of a transmission power value and a waveform attenuation index is hereinafter referred to as the "CAL process of the waveform attenuation method." Note that the RX may perform the light load state control and the load connection state control after notifying the TX, respectively. Also, either of the two controls may be performed first.

[0092] The calculation process of the threshold value used to determine the presence or absence of a foreign object for each load (or each transmission power value) described in this embodiment may be performed in the calibration phase. As described above, the TX acquires data required for foreign object detection using the power loss method in the calibration phase. At that time, the TX acquires data related to power loss when the load state of the RX is a light load state and when a load is connected. Therefore, measurements of CP1100 and CP1101 in FIG. 8 may be performed together with power loss measurements in the calibration phase when the RX is in a light load state and a load connected state. For example, when the TX receives a signal containing first reference received power information from the RX, the TX measures CP1100 in addition to the predetermined processing to be performed in the calibration phase. This first reference received power information is information in a Received Power Data packet (mode 1) specified in the WPC standard, but other messages may also be used. Furthermore, when TX receives a signal containing second reference received power information from RX, it measures CP1101 in addition to the predetermined processing to be performed in the calibration phase. This second reference received power information is information in the Received Power Data packet (mode 2) specified in the WPC standard, but other messages may also be used. Since there is no need to set aside a separate period for measuring CP1100 and CP1101, measurements of CP1100 and CP1101 can be performed in a shorter time.

[0093] Furthermore, when using, for example, a Q-factor calculated from the above formula 1 as the waveform attenuation index, there is a method of setting a threshold based on the Reference Quality Factor Value. The Reference Quality Factor Value is included in the FOD Status Data packet and transmitted by the RX to the TX. This Reference Quality Factor Value is the Q-factor that can be measured at the terminal of the power transmitting antenna of the test TX when the RX is placed on the test TX and there is no foreign object nearby. Since the Reference Quality Factor Value is physically equivalent to the Q-factor calculated from the above formula 1, it is possible to set a threshold using this. Note that the value of the waveform attenuation index obtained by adding a predetermined value (a value corresponding to the measurement error) to the Reference Quality Factor Value may be set as the threshold for determining the presence or absence of a foreign object.

[0094] The TX may also perform the waveform attenuation method when there is no foreign object (when there is no abnormality) and set the measurement result of the waveform attenuation index as the threshold. The timing for pre-measuring the waveform attenuation rate when there is no foreign object will be described below. In the negotiation phase of the WPC standard, if foreign object detection using the Q-factor measurement method is performed and it is determined that there is no foreign object, the TX proceeds to the calibration phase and the power transfer phase. In other words, proceeding to the negotiation phase or later means that the foreign object detection using the Q-factor measurement method has determined that there is no foreign object. It is highly likely that the waveform attenuation index when there is no foreign object can be measured in any of the negotiation phase, calibration phase, and power transfer phase. Therefore, the timing for measuring the waveform attenuation index when there is no foreign object may be any of the negotiation phase, calibration phase, and power transfer phase.

[0095] For example, assume that the waveform attenuation index is measured during the power transfer phase. The timing for measuring the waveform attenuation index when there is no foreign object is set to the beginning of the power transfer phase. The reason for this is that the more time that passes since the Q-factor measurement method determines that there is no foreign object, the higher the probability that a foreign object will be present near the TX and RX. The timing is specified by the RX or TX, and the TX measures the waveform attenuation index at that time and sets the value of that waveform attenuation index as the threshold. Note that a value obtained by adding a predetermined value (a value corresponding to the measurement error) to the waveform attenuation index may also be set as the threshold for determining the presence or absence of a foreign object.

[0096] The number of thresholds for determination set by the above method is not limited to one. Multiple thresholds can be set in stages. For example, the first threshold is set as a threshold for determining "there is a status abnormality," the second threshold is set as a threshold for determining "there is a high possibility of a status abnormality," the third threshold is set as a threshold for determining "there is a low possibility of a status abnormality," and the fourth threshold is set as a threshold for determining "there is no status abnormality."

[0097] Next, a first measurement method will be described as a method for measuring the coupling state between the power transmitting antenna and the power receiving antenna. In wireless power transmission, power is transmitted by electromagnetically coupling the power transmitting antenna 105 and the power receiving antenna 205. An AC current is passed through the power transmitting antenna 105, changing the magnetic flux penetrating the power receiving antenna 205, thereby inducing a voltage in the power receiving antenna 205. The coupling coefficient (denoted as k), which is an index representing the coupling state between the power transmitting antenna and the power receiving antenna, is, for example, "k = 1" when all (100%) of the magnetic flux generated by the power transmitting antenna penetrates the power receiving antenna. Similarly, when 70% of the magnetic flux generated by the power transmitting antenna penetrates the power receiving antenna, it is "k = 0.7." In this case, the remaining (30%) magnetic flux generated by the power transmitting antenna is leakage magnetic flux. This is the magnetic flux generated by the power transmitting antenna that does not penetrate the power receiving antenna. Therefore, when the coupling between the transmitting antenna and the receiving antenna is good and the k value is large, the transmission efficiency of power transmitted from TX to RX is high. Conversely, when the coupling is poor and the k value is small, the transmission efficiency of power transmitted from TX to RX is low.

[0098] Factors that can cause a decrease in the value of the coupling coefficient include the presence of a foreign object (such as a metal piece) between the power transmitting antenna and the power receiving antenna, or misalignment between the power transmitting antenna and the power receiving antenna. If a foreign object is present between the power transmitting antenna and the power receiving antenna, heat may be generated in the foreign object. Furthermore, misalignment between the power transmitting antenna and the power receiving antenna increases leakage magnetic flux, which may generate significant noise in the surrounding area. When the k value is small, appropriate control is required to achieve safer, higher-quality wireless power transmission. In this embodiment, a process is performed to detect the coupling state (including the coupling coefficient) between the power transmitting antenna and the power receiving antenna in order to improve the accuracy of detecting foreign objects and misalignment.

[0099] A method for measuring the coupling state between a power transmitting antenna and a power receiving antenna will be described with reference to Fig. 9. Fig. 9(A) is an equivalent circuit diagram for explaining the first measurement method. The definitions of various quantities related to the power transmitting antenna (power transmitting coil) on the primary side (TX) are shown below. · r1: Transmitting coil winding resistance. L1: Self-inductance of the transmitting coil. V1: The transmitting voltage (input voltage) across the transmitting coil measured by the TX. The definitions of the various quantities related to the receiving antenna (receiving coil) on the secondary side (RX) are shown below. · r2: Winding resistance of the receiving coil. L2: Self-inductance of the receiving coil. V2: The receiving voltage (output voltage) across the receiving coil measured by RX.

[0100] The coupling coefficient k between the power transmitting coil and the power receiving coil can be calculated using the following formula 2. k=(V2 / V1) √(L1 / L2) (Equation 2) When the TX calculates the coupling coefficient k, the RX notifies the TX of the measured receiving voltage V2 and the value of the self-inductance L2 of the receiving coil that the RX holds in advance. The TX calculates the k value using the measured transmitting voltage V1, the value of the self-inductance L1 of the transmitting coil that the TX holds in advance, and the values ​​of the receiving voltage V2 and self-inductance L2 received from the RX. Alternatively, the RX can notify the TX of V2, as well as a constant calculated using either or both of L1 and L2, and the TX can calculate the k value using the constant received from the RX, V2, and the transmitting voltage V1 measured by the TX.

[0101] On the other hand, when RX calculates the coupling coefficient k, TX notifies RX of the measured transmitting voltage V1 and the value of the self-inductance L1 of the transmitting coil that it has stored in advance. RX calculates the k value using the measured receiving voltage V2, the value of the self-inductance L2 of the receiving coil that it has stored in advance, and the values ​​of the transmitting voltage V1 and self-inductance L1 received from TX. Alternatively, TX can notify RX of V1, as well as a constant calculated using either or both of L1 and L2, and RX can calculate the k value using the constant received from TX, V1, and the receiving voltage V2 measured by RX.

[0102] The transmission voltage V1 is calculated by the TX either by actually measuring the voltage applied to the transmission coil or by the TX from the set value of the transmission power. Alternatively, the transmission voltage V1 may be set as the set value of the transmission voltage during power transmission. Furthermore, the transmission voltage V1 applied to the transmission coil can be calculated from the transmission voltage (denoted as V3) applied to a circuit (e.g., an inverter) included in the power transmitting unit 103 of the TX and the voltage applied across the resonant capacitor 107. In this case, the transmission voltage V3 may also be calculated by the TX from the set value of the transmission power. Alternatively, the TX may actually measure the transmission voltage V3 and the voltage applied across the resonant capacitor 107 and use these to calculate the transmission voltage V1.

[0103] Furthermore, when TX or RX performs the first measurement, RX may turn off third switch unit 213 to open the terminals of power receiving antenna 205. This allows both ends of the power receiving coil to be open, as shown in FIG. 9A. Since the first measurement is not affected by resonant capacitor 211, power receiving unit 203, charging unit 206, or battery 207, it is possible to measure coupling coefficient k with higher accuracy. Furthermore, power receiving voltage V2 applied to the power receiving coil can be calculated from the power receiving voltage (denoted as V4) applied to a circuit (e.g., a rectifier) ​​included in power receiving unit 203 of RX and the voltage applied across resonant capacitor 211. In this case, RX may actually measure power receiving voltage V4 and the voltage across resonant capacitor 211 and use these measurements to calculate power receiving voltage V2.

[0104] Alternatively, when the TX or RX performs the first measurement, the RX may be controlled to be in a light load state or in a loaded state. By keeping the load state of the RX constant, it is possible to measure the coupling coefficient k with higher accuracy.

[0105] In addition to the coupling coefficient, there are several other quantities that can be used as indices to represent the electromagnetic coupling state between the power transmitting antenna and the power receiving antenna. In this embodiment, these are collectively referred to as "coupling state indices." Each coupling state indices has a value that corresponds to the electromagnetic coupling state between the power transmitting antenna and the power receiving antenna. The contents of this embodiment can also be applied to cases where a coupling state indices other than the coupling coefficient are used.

[0106] For example, the coupling state index may be a transmission voltage V3 applied to a circuit (e.g., an inverter) included in the power transmitting unit 103 of the TX, and a receiving voltage (denoted as V4) applied to a circuit (e.g., a rectifier) ​​included in the power receiving unit 203 of the RX. These may be used to calculate the coupling state between the power transmitting antenna and the power receiving antenna. Alternatively, the coupling state between the power transmitting antenna and the power receiving antenna may be calculated using the output voltage (denoted as V5) of a circuit (e.g., a rectifier) ​​included in the power receiving unit 203 of the RX. The output voltage V5 is the voltage applied to a load (charging unit, battery). The TX notifies the RX of the transmission voltage V3, which enables the RX to calculate the coupling state index. At this time, the TX notifies the RX of a constant calculated using the electrical characteristics (e.g., L1) of the power transmitting antenna, and the RX can calculate the coupling state index using this constant.

[0107] Alternatively, RX notifies TX of the receiving voltage V4 or the output voltage V5, and TX calculates the value of the coupling status index. At this time, RX notifies TX of a constant calculated using the electrical characteristics of the receiving antenna (e.g., L2), and TX can calculate the coupling status index using the constant.

[0108] The TX and RX exchange information such as voltage values ​​V1 to V5, values ​​of self-inductance L1 and L2, or constants that represent the electrical characteristics of the transmitting and receiving antennas. The timing of measuring voltage values ​​and the timing of sending and receiving each piece of information are explained below. Measurement of each voltage value is performed, for example, during the Ping phase. During the Ping phase, the TX sends a Digital Ping to the RX. Therefore, any of the voltage values ​​V1, V2, V3, V4, and V5 that are generated when the Digital Ping is sent can be used. During the Ping phase, the TX and RX measure any of the values ​​V1 to V5 and store it in memory 106 or memory 208.

[0109] The TX receives a predetermined packet containing information on one of the voltage values ​​V2, V4, and V5 notified by the RX and stores the information in memory 106. The information contained in the predetermined packet may include not only the RX's receiving voltage but also information such as the received power, the self-inductance L2 value, and a constant calculated using the electrical characteristics of the receiving antenna. The predetermined packet may be a Signal Strength Data packet to notify the TX of the RX's information. Alternatively, the predetermined packet may be an Identification Data packet, Extended Identification Data packet, or Configuration Data packet in the I&C phase. Alternatively, it may be a packet in the Calibration phase or Power Transfer phase. That is, it may be a Received Power Data packet (mode 1), a Received Power Data packet (mode 2), or a Received Power Data packet (mode 0). Note that the TX is not limited to using the voltage value generated when transmitting a Digital Ping. The TX may also use one of the voltage values ​​V1 to V5 generated when transmitting an Analog Ping in the Selection phase.

[0110] When performing the first measurement, RX may turn off third switch unit 213 located between resonant capacitor 211 and power receiving unit 203, and perform control so that the terminal of the circuit formed by power receiving antenna 205 and resonant capacitor 211 is in an open state. This prevents the power receiving unit 203, charging unit 206, and battery 207 from affecting the first measurement, making it possible to measure the coupling state index with higher accuracy.

[0111] Next, we will explain a second measurement method as another example of a method for measuring the coupling state between a transmitting antenna and a receiving antenna. Figure 9(B) is an equivalent circuit diagram for explaining the second measurement method. r1, r2, L1, and L2 are the same as in Figure 9(A). The definitions of various quantities related to the transmitting antenna (transmitting coil) on the primary side (TX) are shown below. ·V6: Input voltage of the transmitting antenna when the receiving antenna is shorted. ·V7: Input voltage of the transmitting antenna when the receiving antenna side is open. I1: The current that flows through the transmitting antenna when the receiving antenna is shorted. I2: The current flowing through the transmitting antenna when the receiving antenna is open.

[0112] The coupling coefficient k can be calculated by the following equation 3. k=√(1-Lsc / Lopen) (Equation 3) In Equation 3, Lsc represents the inductance of the transmitting coil when both ends of the receiving coil are short-circuited. For example, the control unit 201 turns the third switch unit 213 and the second switch unit 210 on (short-circuited state). The Lsc value can be obtained by measuring the inductance value of the transmitting coil in this state. The inductance value of the transmitting coil can be calculated from the input voltage V6 and current I1 of the transmitting coil.

[0113] In Equation 3, Lopen represents the inductance of the transmitting coil when both ends of the receiving coil are open. For example, the control unit 201 sets the third switch unit 213 to the OFF state (open state). In this state, the Lopen value can be obtained by measuring the inductance value of the transmitting coil. The inductance value of the transmitting coil can be calculated from the input voltage V7 and current I2 of the transmitting antenna. In the second measurement method, the coupling state index (coupling coefficient) can be calculated from the input voltage and current of the transmitting antenna when both ends of the receiving antenna are short-circuited and when they are open.

[0114] The TX can also calculate a coupling state index based on the transmission voltage and current applied to a circuit (e.g., an inverter) included in the power transmitting unit 103. In this case, the input voltages V6 and V7 represent the transmission voltage applied to a circuit (e.g., an inverter) included in the power transmitting unit 103. The input voltages V6 and V7 may also be the voltage applied to both terminals of a series resonant circuit consisting of a power transmitting antenna and a resonant capacitor. Alternatively, the transmission voltage applied to a circuit (e.g., an inverter) included in the power transmitting unit 103 and the voltage applied across the resonant capacitor 107 may be measured, and the voltage applied to the power transmitting antenna may be calculated from the results. In other words, the coupling state index can be found from the measurement results of the transmission voltage applied to a circuit (e.g., an inverter) included in the power transmitting unit 103 and the voltage applied across the resonant capacitor 107. In this case, the TX may calculate the transmission voltage applied to a circuit (e.g., an inverter) included in the power transmitting unit 103 from the set value of the transmission power.

[0115] 9(B), the current I1 or I2 is not limited to a current flowing through the power transmitting antenna, and may be, for example, a current flowing through a circuit (e.g., an inverter) included in the power transmitting unit 103. The open state and short state of the power receiving antenna have been described as being realized by the control unit 201 controlling the second switch unit 210 and the third switch unit 213. These states may also be realized by the power receiving unit 203. Instead of the short state, a light load state may be used.

[0116] In the second measurement method, the TX can calculate the coupling status index by measuring the input voltages V6 and V7 and the currents I1 and I2. Therefore, information such as the voltage values ​​measured by the RX and the inductance value of the receiving antenna is not required, and the RX does not need to notify the TX of this information. However, when the TX measures the input voltage V6 and the current I1, the RX must short both terminals of the circuit containing the receiving antenna. Also, when the TX measures the input voltage V7 and the current I2, the RX must open both terminals of the circuit containing the receiving antenna. In other words, depending on the timing at which the TX measures the input voltage and current, the RX must control both terminals of the circuit containing the receiving antenna to a short or open state. The measurement timing is determined either by the TX and notified to the RX, or by the RX and notified to the TX. This notification is carried out by communication based on the WPC standard between the first communication unit 104 of the TX and the first communication unit 204 of the RX, or by communication based on a standard other than the WPC standard between the second communication unit 109 of the TX and the second communication unit 212 of the RX.

[0117] Measurement of input voltages V6, V7 and currents I1, I2 is performed, for example, during the Ping phase. During the Ping phase, the TX transmits a Digital Ping to the RX. Therefore, the values ​​of V6, V7 and currents I1, I2 generated when the Digital Ping is transmitted can be used. During the Ping phase, the TX acquires the values ​​of V6, V7, I1, and I2 and stores them in the memory 106 to calculate the coupling status index. Note that the present invention is not limited to the example in which the TX uses the voltage values ​​and current values ​​generated when the Digital Ping is transmitted. For example, the values ​​of V6, V7, I1, and I2 generated when the TX transmits an Analog Ping during the Selection phase can also be used.

[0118] In this disclosure, both the first and second measurement methods are applicable to the method of measuring the coupling state between a power transmitting antenna and a power receiving antenna. The following describes a method of setting a state determination threshold for a coupling state indicator acquired by the first or second measurement method. The state determination includes, for example, determining whether a foreign object is detected between the power transmitting antenna and the power receiving antenna, or whether a misalignment between the power transmitting antenna and the power receiving antenna is detected. By implementing the first or second measurement method, it is possible to determine whether a state abnormality exists using the state determination threshold. The following describes the first to fourth threshold setting methods.

[0119] The first threshold setting method is a method in which the value of the coupling status indicator used to detect the status between the transmitting antenna and the receiving antenna when there is no abnormality is set as the threshold. The status detection produces a judgment result such as "there is an abnormality," "there is a high possibility of an abnormality," "there is a low possibility of an abnormality," or "there is no abnormality." Assume that the RX is mounted on the test TX and there is no abnormality between the transmitting antenna and the receiving antenna. In this case, the value of the coupling status indicator between the test TX including the transmitting antenna and the RX including the receiving antenna can be set as the threshold. The RX stores the value of the coupling status indicator (threshold) measured in advance in its memory, and notifies the TX of the threshold. The TX uses the threshold to perform judgment processing related to status detection. The RX may transmit this threshold to the TX by including it in the FOD Status Data packet specified in the WPC standard.

[0120] The second threshold setting method is a method in which the coupling status indicators measured by the TX and RX using the first or second measurement method are set as thresholds when there is no abnormal status between the transmitting and receiving antennas. To confirm that there is no abnormal status between the transmitting and receiving antennas, a TX and RX status detection method, such as a power loss foreign object detection method or a Q-factor measurement method, can be used. If it is determined that there is no abnormal status, it can be confirmed with a high probability that there is no abnormal status between the transmitting and receiving antennas. In other words, this confirmation is performed using a method and means other than the first or second measurement method. If it is determined that there is no abnormal status (or no foreign object), the coupling status indicator is measured using the first or second measurement method, and an appropriate threshold is set based on the measurement results.

[0121] For example, in the WPC standard, foreign object detection processing using the Q-factor measurement method is performed in the negotiation phase or renegotiation phase. If the foreign object detection processing results in a "no abnormality" (or "no foreign object"), the coupling status indicator is measured using the first or second measurement method after the negotiation phase or renegotiation phase. A more appropriate threshold value can be set based on the measurement results. Furthermore, foreign object detection processing using the power loss method is performed during the power transfer phase. After the foreign object detection processing is performed, the coupling status indicator is measured using the first or second measurement method, and a more appropriate threshold value can be set based on the measurement results. Alternatively, foreign object detection processing can be performed using the Q-factor or the like in the selection phase or ping phase. In this case, the coupling status indicator is measured using the first or second measurement method after the phase in which the foreign object detection processing is performed, and an appropriate threshold value can be set based on the measurement results.

[0122] A third threshold setting method will be described with reference to Fig. 10. Fig. 10 is a diagram illustrating a threshold setting method for state detection using a coupling state index. In Fig. 10, the horizontal axis represents transmitted power, and the vertical axis represents the coupling state index. On the graph line indicated by straight line segment 1202, point 1200 corresponds to transmitted power value Pt1 and coupling state index value k1, and point 1201 corresponds to transmitted power value Pt2 and coupling state index value k2. On the graph line, point 1203 corresponds to transmitted power value Pt3 and coupling state index value k3. Below, an example will be shown in which the coupling state index value is calculated in the first measurement method using received voltage V4 or output voltage V5 applied to a circuit (e.g., a rectifier) ​​included in power receiving unit 203 of RX.

[0123] As shown in Figure 3, the charging unit 206 and battery 207 are connected as loads to the power receiving unit 203 of the RX, so the calculated coupling status index value changes depending on the load status. To determine whether or not a status abnormality exists depending on the load status, a threshold value for the coupling status index must be set. First, when power is transmitted from the TX, the RX controls the load so that it is in a light load state. A light load state is a state in which no power is supplied to the RX load or only power below the threshold is supplied. The transmitted power value in this state is defined as Pt1. In this state, the TX and RX measure the input voltage on the TX side and the received voltage on the RX side. The TX and RX exchange information about the input voltage and received voltage, and the TX or RX calculates the coupling status index value k1. At this time, the TX recognizes the transmitted power value Pt1 and stores in memory the CP1200 that associates Pt1 and k1. Next, the RX controls the RX load so that it is in a load-connected state when power is transmitted from the TX. The RX load is supplied with maximum power or with power above the threshold. The transmission power value of the TX in this state is Pt2. The TX and RX measure the input voltage on the TX side and the receiving voltage on the RX side in this state. The TX and RX exchange information on the input voltage and receiving voltage, and the TX or RX calculates a coupling status index value k2. The TX stores CP1201, which associates Pt2 with k2, in its memory. The TX then performs linear interpolation between CP1200 and CP1201 to generate line segment 1202. Line segment 1202 shows the relationship between the transmission power and the coupling status index when there are no abnormal conditions around the TX and RX. The TX can use line segment 1202 to estimate the coupling status index value for each transmission power value when there are no abnormal conditions around the TX and RX. For example, assume that the transmission power value is Pt3. In this case, the coupling status index value can be estimated as k3 from point 1203 on line segment 1202, which corresponds to the transmission power value Pt3. Based on the estimation result, the TX can calculate a threshold value used to determine the presence or absence of a state abnormality for each transmission power value. For example, it is possible to set a coupling state index value obtained by adding a predetermined value (a value corresponding to a measurement error) to the estimation result of the coupling state index value when there is no state abnormality at a certain transmission power value as the determination threshold.

[0124] The CAL process performed by the power transmitting device 100 and the power receiving device 200 in order for the power transmitting device 100 to acquire a combination of the transmitted power value and the coupling state index value is called the "CAL process of the coupling state measurement method." Note that the RX may perform the control to put the load into a light load state and the control to put the load into a load connected state after notifying the TX that they will perform the respective controls. Furthermore, either of these two controls may be performed first.

[0125] In this embodiment, the operation for calculating the judgment threshold for state detection for each load (or each transmitted power value) is performed, for example, in the calibration phase. In the calibration phase, the TX acquires data required for foreign object detection using the power loss method. At that time, the TX acquires data on the amount of power loss when the load state of the RX is a light load state and when the load state of the RX is a loaded state. Therefore, the measurements of CP1200 and CP1201 in FIG. 10 can be performed together with the power loss measurement when the RX is in a light load state and a loaded state during the calibration phase. That is, when the TX receives first reference received power information from the RX, the TX measures CP1200 in addition to the predetermined processing to be performed in the calibration phase. The first reference received power information is information in the Received Power Data packet (mode 1) specified in the WPC standard, but other messages may also be used. Furthermore, when the TX receives second reference received power information from the RX, the TX measures CP1201 in addition to the predetermined processing to be performed in the calibration phase. The second reference received power information is information in the Received Power Data packet (mode 2) defined in the WPC standard, but other messages may be used. In this way, there is no need to set aside a separate period for measuring CP1200 and CP1201, so CP1200 and CP1201 can be measured in a shorter time.

[0126] The fourth threshold setting method is a method in which TX or RX sets a threshold in advance for a coupling status index having a value within a predetermined range. For example, if the coupling status index is a coupling coefficient k, the range of k value is "0≦k≦1." For example, TX or RX determines that "a status abnormality exists" when "0≦k<0.2" and determines that "a status abnormality is highly likely" when "0.2≦k<0.5." TX or RX determines that "a status abnormality is unlikely" when "0.5≦k<0.8" and determines that "no status abnormality exists" when "0.8≦k≦1." Condition data for the k value is stored in memory in advance, and the determination process is performed based on the conditions.

[0127] Furthermore, when setting a judgment threshold for state detection using a binding state index, a value obtained by adding a predetermined value (a value corresponding to a measurement error) to a binding state index value calculated based on the measurement result or received information can be set as the judgment threshold. Note that the threshold is not limited to one, and multiple thresholds can be set in stages, as described above.

[0128] Next, we will explain the state detection process using the Q-factor measurement method and the method for measuring the coupling state of the power transmitting antenna and the power receiving antenna. By using the Q-factor measurement method in combination with the first or second measurement method, it is possible to perform state detection with higher accuracy. With reference to Figure 11, we will explain the Q-factor measurement method in more detail.

[0129] FIG. 11A is a schematic circuit diagram for explaining a method for measuring a Q-factor using the Q-factor measurement method. The AC power supply 901 is a power supply that outputs AC power generated by the power transmitting unit 103 of the TX. The power transmitting coil 902 corresponds to the power transmitting antenna 105, and the capacitor 903 corresponds to the resonant capacitor 107. The power transmitting coil 902 and the capacitor 903 are connected in series. The voltage value V8 is a voltage value of a predetermined frequency generated by the power transmitting unit 103 for operating the wireless power transmission system. The voltage value V9 is a voltage value applied to the power transmitting coil 902. Here, the TX is assumed to be able to change the frequency related to the voltage value. The voltage values ​​V8 and V9 are voltage values ​​measured by the TX when the TX transmits an Analog Ping or a Digital Ping to the RX. Note that, since the voltage values ​​V8 and V9 are AC voltage values, their effective values ​​(RMS) may also be used.

[0130] FIG. 11(B) shows an example of measurement results of V9 / V8 versus frequency, showing characteristics with a peak at 100 kHz. The horizontal axis represents frequency, and the vertical axis represents the voltage ratio "V9 / V8." V9 / V8 represents the Q-factor associated with the transmitting coil 902, and therefore its value changes when an object is placed near the transmitting coil 902. The change in Q-factor differs between the cases where no object is placed on the TX, where the RX is placed on the TX, where a foreign object (such as a metal piece) is placed on the TX, and where the RX and foreign object are placed on the TX.

[0131] During the negotiation phase, the TX receives an FOD Status Data packet signal from the RX, which includes a Reference Quality Factor Value and a Reference Resonance Frequency Value. The Reference Quality Factor Value is the Q-factor that can be measured at the terminals of the power transmitting antenna of the test TX when the RX is placed on the test TX and there are no foreign objects nearby. The Reference Resonance Frequency Value is the resonance frequency that can be measured at the terminals of the power transmitting antenna of the test TX when the RX is placed on the test TX and there are no foreign objects nearby. In the Q-factor measurement method, a threshold is set based on the Reference Quality Factor Value. Foreign objects are detected by comparing this threshold with the Q-factor obtained from the actually measured V9 / V8. Alternatively, a threshold is set based on the Reference Resonance Frequency Value. Foreign objects are detected by comparing this threshold with the resonance frequency obtained by actually measuring V9 / V8.

[0132] The Q-factor measurement method can mainly detect when a foreign object (such as a metal piece) has entered between the TX and RX, but has low accuracy in detecting misalignment between the TX transmitting antenna and the RX receiving antenna. On the other hand, the coupling status measurement method can detect misalignment between the TX transmitting antenna and the RX receiving antenna, and can also detect when a foreign object (such as a metal piece) has entered between the TX and RX. Using the measurements from each method, the TX and RX are controlled as follows:

[0133] 12 to 14 are sequence diagrams illustrating an example of a control method based on measurements made by the Q-factor measurement method and measurements made by the coupling state measurement method. First, a specific description will be given with reference to FIG. 12. Note that the coupling coefficient k is used as the coupling state index. In F1301, the TX measures the Q-factor based on the Q-factor measurement method. Next, in F1302, the TX performs voltage measurements to calculate the coupling coefficient k based on the first or second measurement method. Specifically, the values ​​of V1, V3, V6, and V7 are acquired. At the same time, the RX performs voltage measurements to calculate the coupling coefficient k based on the first measurement method in F1310. Specifically, the values ​​of V2, V4, and V5 are acquired. Note that when the second measurement method is used, voltage measurements on the RX side are not necessary.

[0134] These voltage measurements can be performed by both TX and RX when TX sends an Analog Ping or a Digital Ping. In other words, F1301, F1302, and F1310 can perform measurements at the same time. This allows measurements to be completed in a short time.

[0135] Next, in F1303, RX notifies TX, which calculates the coupling coefficient k, of the information necessary to calculate the coupling coefficient k. Alternatively, if RX is the entity that calculates the coupling coefficient k, TX notifies RX of the information necessary to calculate the coupling coefficient k. The information necessary to calculate the coupling coefficient includes the values ​​of V1 to V7, the values ​​of the self-inductances L1 and L2, or constants calculated using the electrical characteristics of the transmitting antenna and the receiving antenna.

[0136] In F1304, the TX performs a calculation process for the coupling coefficient k. Alternatively, the RX may calculate the coupling coefficient k. Then, in F1305, the RX notifies the TX of the Reference Quality Factor Value and Reference Resonance Frequency Value used in the Q-factor measurement method. The notification method is as described above. In F1306, the TX sets a threshold for the Q-factor in the Q-factor measurement method according to the threshold setting method. Alternatively, it sets a threshold for the resonance frequency in the Q-factor measurement method. Next, in F1307, the TX sets a threshold for the coupling coefficient k in the coupling state measurement method according to the threshold setting method.

[0137] In F1308, the TX determines whether the measured Q-factor is within a first threshold range. The first threshold range is a determination criterion determined by a threshold related to the Q-factor. Alternatively, the first threshold range is a determination criterion determined by a threshold related to the resonant frequency. Hereinafter, the term "Q-factor measurement" includes both the measurement of the Q-factor using the Q-factor measurement method and the measurement of the resonant frequency using the Q-factor measurement method. Furthermore, the terms "measured Q-factor" or "Q-factor value" include both the measurement of the Q-factor using the Q-factor measurement method and the measurement of the resonant frequency using the Q-factor measurement method. Furthermore, the term "Q-factor threshold" includes both the threshold related to the Q-factor using the Q-factor measurement method and the threshold related to the resonant frequency using the Q-factor measurement method. Here, assuming that the measured Q-factor is within the first threshold range, the TX proceeds to the next step F1309 and determines whether the coupling coefficient k is within a second threshold range. The second threshold range is a judgment standard determined by a threshold related to the coupling coefficient k. Here, let's assume that the coupling coefficient k is within the second threshold range. In this case, the coupling coefficient k is within the second threshold range, and the measured Q-factor is within the first threshold range, so the TX determines that there is no abnormality near the transmitting antenna and the receiving antenna. Therefore, after going through each phase of the WPC standard, the system moves to the Power Transfer phase, and the TX starts transmitting power to the RX at F1311.

[0138] The determination process based on whether the measurement result is within a predetermined range based on a set threshold is one example. For example, the Q-factor and the coupling coefficient k are measured multiple times, and the difference between the previous measurement result and the current measurement result is calculated. If this difference is equal to or less than the threshold, it can be determined that there is no abnormality or that there is a low possibility of an abnormality. If the difference is greater than the threshold, it can be determined that there is an abnormality or that there is a high possibility of an abnormality. This determination method can also be applied to the embodiments described later. The order of steps F1301 to F1307 may be different. For example, FIG. 12 shows an example in which the Q-factor is measured and the coupling coefficient k is calculated, and then the Q-factor threshold and the coupling coefficient threshold are set. However, the order may be reversed. The TX may transmit power to the RX so as to satisfy the maximum GP that can be transmitted.

[0139] The TX detects the condition (detects abnormal conditions, foreign objects, etc.) using two parameters, the coupling coefficient k and the Q-factor (including the resonance frequency), enabling more accurate judgments. In other words, if the values ​​of the coupling coefficient k and the Q-factor are both within the corresponding predetermined threshold ranges, the TX can determine with high accuracy that there is no abnormality.

[0140] Next, an example of FIG. 13 will be described. F1301 to F1308 and F1310 are the same as those in FIG. 12, so their description will be omitted. After F1308, the process proceeds to F1312. The TX determines whether the coupling coefficient k is within a second threshold range based on a threshold. Here, it is assumed that the coupling coefficient k is outside the second threshold range. Next, in F1313, the TX notifies the RX that the coupling coefficient k is outside the second threshold range and requests the execution of predetermined control (hereinafter referred to as the first control). Then, in F1314, the TX or RX performs the first control. The first control is a control that addresses misalignment between the power transmitting antenna and the power receiving antenna. The specific content of the first control will be described later.

[0141] As described above, the Q-factor measurement method can detect the presence of foreign matter (such as metal fragments), but has low accuracy in detecting misalignment between the power transmitting antenna and the power receiving antenna. On the other hand, the coupling state measurement method for the power transmitting antenna and the power receiving antenna can detect not only the misalignment between the power transmitting antenna and the power receiving antenna, but also the presence of foreign matter (such as metal fragments). In the example of Figure 13, the measured Q-factor by the Q-factor measurement method is within the first threshold range, indicating that there is little possibility of a foreign matter being present between the power transmitting antenna and the power receiving antenna. Furthermore, the coupling coefficient k measured by the coupling state measurement method is outside the second threshold range, indicating that there is a possibility of misalignment between the power transmitting antenna and the power receiving antenna.

[0142] The first control content of the first control in F1314 is for RX to send an EPT (End Power Transfer) command to TX, which is a command to end power transmission. If a positional misalignment occurs, there is a possibility that power transmission efficiency will decrease or noise in the surrounding environment will increase. As a countermeasure, power transmission from TX to RX will be stopped or a reset will be performed to transition to the first phase, the Selection phase. Note that stopping power transmission is an example of power transmission restriction, and TX sends a transmission request to RX requesting RX to send a notification request of power transmission restriction. At that time, TX can notify the reason for the transmission request. RX determines whether to send a notification request of power transmission restriction to TX based on the transmission request. When RX requests TX to notify of power transmission restriction (for example, changing the power value to a value below the rated power value or stopping power transmission), TX controls power transmission restriction.

[0143] The second control content of the first control in F1314 is for the RX to notify the user to prompt the relocation of the RX on the TX. This can be achieved by, for example, using the UI unit 202 to output various types of information to the user. The various types of information include screen displays on an LCD panel or the like, flashing or color changes of an LED, audio output from a speaker, and vibration of the RX body using a vibration motor or the like. If the RX on the TX is optimally positioned as a result of the notification to the user, the likelihood of appropriate power transmission from the TX to the RX increases.

[0144] The third control content of the first control in F1314 is for the TX or RX to automatically adjust the positions of the power transmitting antenna and the power receiving antenna to increase the coupling coefficient k. In this case, the TX or RX is assumed to have a mechanical unit that moves or changes the attitude of the power transmitting antenna or the power receiving antenna. For example, the TX controls the mechanical unit to adjust the position or attitude of the power transmitting antenna relative to the power receiving antenna. Alternatively, the TX sends to the RX a control request to adjust the position or attitude of the power receiving antenna relative to the power transmitting antenna. The RX receives the request and controls the mechanical unit to adjust the position or attitude of the power receiving antenna relative to the power transmitting antenna. Alternatively, the RX sends to the TX a control request to adjust the position or attitude of the power transmitting antenna relative to the power receiving antenna. The TX receives the request and controls the mechanical unit to adjust the position or attitude of the power transmitting antenna relative to the power receiving antenna. The TX or RX automatically adjusts the relative positions of the power transmitting antenna and the power receiving antenna, and measures the coupling coefficient k as needed or periodically to search for the optimal relative position. This increases the likelihood that power will be transmitted properly from TX to RX when the RX is optimally positioned on the TX.

[0145] The fourth control content of the first control in F1314 is that TX and RX negotiate with each other through communication to set a power value below the threshold and transmit power from TX to RX. For example, a minimum power value is set as the GP value, and TX transmits power to RX. This reduces the power transmitted from TX to RX, thereby reducing noise emitted into the surrounding environment during power transmission. The TX may also transmit power to RX by changing the GP value according to the value of the coupling coefficient k. If the coupling coefficient k is smaller than the threshold (e.g., k = 0.3), the GP is set to 5 (W). If the coupling coefficient k is larger than the threshold (e.g., k = 0.6), the GP is set to 10 (W). If the coupling coefficient k is even larger (e.g., k = 0.9), the GP is set to 15 (W), and TX transmits power to RX at the maximum power it can transmit. The GP value is changed by setting the threshold range of the coupling coefficient k in stages, or the GP value corresponding to the value of the coupling coefficient k is continuously changed, thereby controlling the transmitted power. Furthermore, GP may be replaced with a Maximum Power Value or Reference Power, which is a value specifying the maximum power.

[0146] The fifth control content of the first control in F1314 is changing the frequency bands used by TX and RX for power transmission. The power transmission efficiency in wireless power transmission is determined by the product of the coupling coefficient k and the Q-factor. If the coupling coefficient k is outside a predetermined threshold range, the power transmission efficiency decreases. On the other hand, since the coupling coefficient k and the Q-factor have frequency characteristics, changing the frequency band used for wireless power transmission changes the coupling coefficient k and the Q-factor. As a result, it is possible to improve the power transmission efficiency. For example, TX transmits power to RX by changing the frequency band used for wireless power transmission according to the acquired value of the coupling coefficient k. If the value of the coupling coefficient k is smaller than the threshold (e.g., k = 0.3), TX transmits power to RX using the first frequency band. If the coupling coefficient k is greater than or equal to the threshold (e.g., k = 0.6), TX transmits power to RX using the second frequency band. If the value of the coupling coefficient k is even larger (e.g., k = 0.9), TX transmits power to RX using the third frequency band. The threshold range for the coupling coefficient k is set in stages, and the TX changes the frequency band used when transmitting power to the RX. The TX may also change the frequency band continuously according to the coupling coefficient k. Alternatively, instead of the coupling coefficient, a value calculated from the coupling coefficient k and the Q-factor (for example, the product of the coupling coefficient k and the Q-factor) may be used. The TX changes the frequency band used according to the value calculated from the coupling coefficient k and the Q-factor, and transmits power to the RX. Furthermore, if the TX receives information about the received power value from the RX, it can use the received power value of the RX instead of the coupling coefficient. In other words, the TX changes the frequency band used according to the received power value information received from the RX, and transmits power to the RX.

[0147] The frequency band used for power transmission can be changed by changing the circuit configuration of each of the TX and RX. For example, one configuration is to use a switch to switch from the resonant capacitor 107 connected to the power transmitting antenna 105 of the TX to a resonant capacitor (not shown) with a different constant. The frequency band used by the TX and RX for power transmission is basically determined by the electrical characteristics of the power transmitting antenna 105 and the constant value (capacitance) of the resonant capacitor. Therefore, the resonant capacitor 107 can be switched to a capacitor with a different constant value depending on the frequency band to be used. In other words, the resonant capacitor connected to the power transmitting antenna 105 is changed by switching the resonant capacitor according to the value of the coupling coefficient k. Similarly, the RX is configured to switch the resonant capacitor 211 to a capacitor with a different constant value depending on the frequency band to be used. In other words, the resonant capacitor connected to the power receiving antenna 205 is changed by switching the resonant capacitor according to the value of the coupling coefficient k. Furthermore, the timing for the TX and RX to switch the resonant capacitor is after the device changing the frequency notifies the device connected to that device. For example, the TX (or RX) decides to change the frequency band used for power transmission, and after notifying the RX (or TX) of this decision via communication, the TX and RX switch their respective resonant capacitors. Note that a method of changing the circuit configuration of the TX or RX other than the resonant capacitor depending on the value of the coupling coefficient k may also be adopted.

[0148] Although F1314 can address misalignment between the power transmitting antenna and the power receiving antenna, misalignment can potentially generate significant noise if there is a large amount of leakage flux. The frequency band in which noise occurs also depends on the frequency bands used by the TX and RX for power transmission. Therefore, the frequency bands used by the TX and RX for power transmission can be changed depending on the value of the coupling coefficient k, thereby changing the frequency at which noise occurs. In other words, to suppress noise in a specific frequency band, the TX and RX change the frequency bands used for power transmission to reduce noise in that frequency band. The TX and RX also switch the configuration of their noise suppression circuits depending on the value of the coupling coefficient k. Alternatively, the TX and RX switch the configuration of their noise suppression circuits depending on the frequency band used for power transmission. The noise suppression circuits include capacitors, inductors, filters, etc., in the TX and RX circuits. The timing of the switching is the same as in the method described above. The first to fourth control operations may also be appropriately switched depending on the value of the coupling coefficient, etc.

[0149] Next, an example of FIG. 14 will be described. Steps F1301 to F1307 and F1310 are the same as those in FIG. 12, and therefore their description will be omitted. After F1307, the process proceeds to F1315. In F1315, the TX determines whether the measured value of the Q-factor is within the first threshold range. Here, it is assumed that the measured value of the Q-factor is outside the first threshold range. Next, in F1316, the TX determines whether the value of the coupling coefficient k is within the second threshold range. Here, it is assumed that the value of the coupling coefficient k is outside the second threshold range, and the process proceeds to F1317. The TX notifies the RX that both the Q-factor and the coupling coefficient k are outside the threshold ranges and requests the execution of predetermined control (hereinafter referred to as second control). Next, in F1318, the TX or RX performs the second control. The second control is a control to deal with the presence of a foreign object between the power transmitting antenna and the power receiving antenna. The specific content of the second control will be described later.

[0150] The Q-factor measurement method can detect the presence of a foreign object (such as a metal fragment) between the power transmitting and receiving antennas. Furthermore, the coupling coefficient k of the power transmitting and receiving antennas can be reduced by the presence of a foreign object, making it possible to detect the presence of a foreign object. In the example shown in Figure 14, the measured Q-factor value is outside the first threshold range, indicating a high probability that a foreign object exists between the power transmitting and receiving antennas. The coupling coefficient k obtained by the coupling measurement method is outside the second threshold range, indicating a high probability that a foreign object exists between the power transmitting and receiving antennas. Both methods indicate a high probability that a foreign object (such as a metal fragment) exists between the power transmitting and receiving antennas. Therefore, the TX determines that there is a high probability that a foreign object exists between the power transmitting and receiving antennas.

[0151] The first control content of the second control in F1318 is for RX to send an EPT (End Power Transfer) command to TX, which is a command to end power transmission. If a foreign object (such as a metal piece) is present between the power transmitting antenna and the power receiving antenna, the foreign object may generate heat. Therefore, control is performed to stop power transmission from TX to RX or to reset and transition to the first phase, the Selection phase. Note that stopping power transmission is an example of power transmission restriction.

[0152] The second control content of the second control in F1318 is for the TX or RX to notify the user. The notification to the user is a notification urging the user to remove a foreign object between the power transmitting antennas or on the power transmitting antenna. This can be achieved, for example, by using the UI unit 202 of the RX to provide various outputs to the user. The various outputs include an LCD screen display, a blinking or color change of an LED, audio output from a speaker, and vibration of the RX main unit by a vibration motor. Note that the various outputs in F1318 are controlled to be different from the various outputs in F1314 so that the user can distinguish between the two outputs. This allows the user to clearly determine whether there is a possible misalignment between the power transmitting antenna and the power receiving antenna, or whether there is a foreign object between the power transmitting antenna and the power receiving antenna. If the foreign object is removed as a result of the user notification, the TX is more likely to transmit power appropriately to the RX. Alternatively, the TX may have the same functionality as the UI unit 202 of the RX and provide a notification urging the user to remove the foreign object on the TX.

[0153] The third control content of the second control in F1318 is that TX and RX negotiate with each other through communication to set a power value below the threshold and transmit power. For example, a minimum power value is set as the GP value, and TX transmits power to RX. This has the effect of reducing the power transmitted from TX to RX and reducing the amount of heat generated by the foreign object. Note that TX may transmit power to RX by changing the GP value according to the coupling coefficient k or Q-factor, or the values ​​of the coupling coefficient k and Q-factor.

[0154] The fourth control in the second control in F1318 is to change the frequency bands used by the TX and RX for power transmission. This is similar to the fifth control in the first control described in F1314. A Q-factor and coupling coefficient k outside the predetermined threshold range means that power transmission efficiency decreases. Changing the frequency band used for wireless power transmission can improve power transmission efficiency. For example, one method is to change the frequency band used for wireless power transmission according to the coupling coefficient k or the Q-factor value. Another method is to change the frequency band used for wireless power transmission according to the product of the coupling coefficient k and the Q-factor, which is calculated as a value obtained from these two factors. Alternatively, if the TX receives information about the received power value from the RX, one method is to change the frequency band used for wireless power transmission according to the received power value. Furthermore, the TX and RX may change the frequency bands used for power transmission according to the value of the coupling coefficient k, thereby changing the frequency at which noise occurs. In other words, to suppress noise generated in a specific frequency band, one method is to change the frequency bands used by the TX and RX for power transmission to reduce noise in that frequency band. Note that changing the frequency band can be achieved using known methods, such as changing the circuit configuration of the TX and RX. The timing for changing the circuit configuration is after the device that changes the frequency band notifies the device opposite to that device (see F1314).

[0155] The fifth control content of the second control in F1318 is that the TX or RX has a temperature sensor near the power transmitting antenna or power receiving antenna and checks the temperature detection information from the temperature sensor. For example, if a foreign object is present on the TX, the foreign object may be generating heat. The TX compares the temperature sensor detection value with a threshold value. If the detection value is greater than the threshold value, the TX limits power transmission from the TX to the RX (including stopping power transmission) or changes the operating state by resetting. For example, a reset is performed to transition to the first phase, the Selection phase. Alternatively, the RX compares the temperature sensor detection value with a threshold value. If the detection value is greater than the threshold value, the RX sends an execution request to the TX to limit power transmission from the TX to the RX (including stopping power transmission) or change the operating state by resetting. In addition, the first to fourth control contents may be switched appropriately depending on the value of the Q-factor or the coupling coefficient k, or a value calculated from the Q-factor and the coupling coefficient k.

[0156] Next, we will explain a case that does not fall under the conditions shown in Figures 12 to 14. Assume that the first judgment result is that the measured value of the Q-factor is outside the first threshold range, and the second judgment result is that the value of the coupling coefficient k is within the second threshold range. In this case, the TX determines from the first judgment result that there is a possibility that a foreign object has been introduced onto the power transmitting antenna, and performs control similar to the second control in F1318. Alternatively, the TX and RX remeasure the coupling coefficient k and Q-factor.

[0157] An example of operation in this embodiment will be described with reference to Fig. 15 and Fig. 16. Fig. 15 is a flowchart illustrating the operation of TX. Fig. 16 is a flowchart illustrating the operation of RX.

[0158] In S1501 in Figure 15, the Q-factor is measured. Next, in S1502, the TX measures the voltage value using the waveform attenuation method and the coupling state measurement method. In S1503, the TX receives information necessary to calculate the coupling coefficient k from the RX. In S1504, the TX calculates the value of the coupling coefficient k. In S1505, the TX sets a threshold for the Q-factor, and in S1506, it sets a threshold for the coupling coefficient k.

[0159] In S1507, the TX determines whether the measured value of the Q-factor satisfies a first condition. The first condition is that the measured value of the Q-factor is within a first threshold range. If the first condition is satisfied, the process proceeds to S1508; if the first condition is not satisfied, the process proceeds to S1509. In S1508, the TX determines whether the calculated value of the coupling coefficient k satisfies a second condition. The second condition is that the value of the coupling coefficient k is within a second threshold range. If the second condition is satisfied, the process proceeds to S1510; if the second condition is not satisfied, the process proceeds to S1511. The process of S1509 is the same as S1508, so a description thereof will be omitted. If the second condition is satisfied in S1509, the process proceeds to S1512; if the second condition is not satisfied, the process proceeds to S1513.

[0160] In S1510, the TX executes processing to start power transmission. In S1511, the first control is performed. In S1512, the second control is performed, or the coupling coefficient k and the Q-factor are remeasured. In S1513, the second control is performed.

[0161] Meanwhile, in S1601 of Figure 16, the RX measures the voltage value using the waveform attenuation method and the coupling state measurement method. In S1602, the RX sends the TX the information necessary to calculate the coupling coefficient k. In S1603, the RX sends the TX the information necessary to set the Q-factor threshold (Reference Quality Factor Value and Reference Resonance Frequency Value). Next, the process proceeds to S1604.

[0162] In S1604, RX determines whether or not it has received a request to execute the first control from TX. If the request to execute the first control has been received, the process proceeds to S1605; if the request to execute the first control has not been received, the process proceeds to S1606. Also, in S1606, RX determines whether or not it has received a request to execute the second control from TX. If the request to execute the second control has been received, the process proceeds to S1607; if the request to execute the second control has not been received, the process proceeds to S1604. RX performs the first control in S1605, and performs the second control in S1607.

[0163] According to this embodiment, more appropriate control can be performed by using a plurality of detection methods for detecting the states of the power transmitting antenna and the power receiving antenna in wireless power transmission.

[0164] [Second embodiment] A second embodiment will be described with reference to Figs. 17 to 23. In this embodiment, a method for performing more accurate state detection using three methods will be described. The three methods are a power loss method, a waveform attenuation method, and a method for measuring the coupling state between a power transmitting antenna and a power receiving antenna. The features of each method are as follows:

[0165] The waveform attenuation method can detect the presence of a foreign object (such as a metal piece) between the TX and RX, but has low accuracy in detecting misalignment between the power transmitting and power receiving antennas. The power transmitting and power receiving antenna coupling state measurement method and the power loss method can detect misalignment between the power transmitting and power receiving antennas, and can also detect the presence of a foreign object (such as a metal piece) between the TX and RX. In this embodiment, a description of the same matters as in the first embodiment will be omitted, and differences will be mainly described. The following control is performed using the three measurement results obtained by implementing each method.

[0166] 17 to 20 are sequence diagrams illustrating the control in this embodiment. It is assumed that the state determination thresholds in each method are set in a phase before power transmission starts (before the power transfer phase) using the same method as in the first embodiment. However, it is possible to execute the threshold setting process for each method during the power transfer phase using the same method as in the first embodiment.

[0167] First, the example in Figure 17 will be described. In F1501, power transmission from TX to RX begins. In F1502, RX transmits a Received Power Data packet (mode 0) containing information on the received power value to TX. The Received Power Data packet (mode 0) is abbreviated as "RP0". In F1503, TX performs status detection based on the Power Loss method using the information on the received power value of RX contained in RP0. The status detection result here is that the received power value of RX is within the threshold range, and "no abnormality" is detected.

[0168] Next, in step F1504, the TX measures the waveform attenuation index using the waveform attenuation method. The Q-factor is used as the waveform attenuation index. Here, measuring the waveform attenuation index using the waveform attenuation method is referred to as "Q-factor measurement." Next, in step F1505, the TX performs voltage measurements to calculate the coupling coefficient k using either the first or second measurement method. Specifically, the values ​​of V1, V3, V6, and V7 are acquired. Meanwhile, at the same time, the RX performs voltage measurements on its own using the first measurement method in step F1506 to calculate the coupling coefficient k. Specifically, the values ​​of V2, V4, and V5 are acquired. Note that if the second measurement method is used, voltage measurements on the RX side are not necessary. The TX can measure the voltage generated when transmitting power to the RX, and the RX can measure the voltage generated when receiving power from the TX. In other words, the measurements in steps F1504, F1505, and F1506 can be performed simultaneously.

[0169] Furthermore, RP0 shown in F1502 may include an implementation request of F1504 to TX. RP0 may also include the voltage measurement result by RX in F1506. This makes it possible to shorten the processing time. Furthermore, RP0 may be replaced by a Received Power Data packet (mode 1) (hereinafter abbreviated as RP1) or a Received Power Data packet (mode 2) (hereinafter abbreviated as RP2). This method is also applicable to the first embodiment.

[0170] Next, in F1507, RX notifies TX of information for calculating the coupling coefficient k. Alternatively, if RX calculates the coupling coefficient k, TX notifies RX of information for calculating the coupling coefficient k. The information for calculating the coupling coefficient k includes the values ​​of V1 to V7, L1 and L2, and constants calculated using the electrical characteristics of the transmitting antenna and the receiving antenna.

[0171] Furthermore, RP0 (or RP1, RP2) may include information for calculating the coupling coefficient in F1507. This can shorten the processing time. In F1508, TX calculates the coupling coefficient k. Alternatively, RX may calculate the coupling coefficient k. Next, in F1509, TX determines whether the value of the Q-factor is within the first threshold range. Here, it is assumed that the value of the Q-factor is within the first threshold range, and the process proceeds to F1510, where TX determines whether the value of the coupling coefficient k is within the second threshold range. Here, it is assumed that the calculated value of the coupling coefficient k is within the second threshold range.

[0172] In the example of Fig. 17, the received power value of RX is within the threshold range, and the acquired values ​​of the coupling coefficient k and Q-factor are within their respective threshold ranges. TX determines that "there is no abnormality near the transmitting antenna and the receiving antenna," and continues transmitting power at F1511.

[0173] When measuring the Q-factor or coupling coefficient k multiple times, one method is to make a judgment regarding status detection by comparing the difference between the previous measurement result and the current measurement result with a threshold. Also, when TX receives RP0 from RX multiple times, another method is to make a judgment regarding status detection by comparing the difference between the information received last time and the information received this time with a threshold. Also, the order of F1503 to F1510 may be changed. For example, the Q-factor may be measured first, and then the Power Loss method may be performed. Also, TX may transmit power to RX at the maximum GP it can transmit.

[0174] As described above, the TX can make a highly accurate determination of the status detection by using three parameters: the received power of the RX, the coupling coefficient k, and the Q-factor. For example, if the values ​​of the three parameters are within their respective threshold ranges, a highly accurate determination result of "no abnormality" can be obtained.

[0175] Next, an example of Fig. 18 will be described. F1501 to F1509 are the same as those of Fig. 17, so their description will be omitted. After F1509, the process proceeds to F1512. In F1512, the TX determines whether the value of the coupling coefficient k is within the second threshold range, and assumes that the value of the coupling coefficient k is outside the second threshold range. Next, in F1513, the TX notifies the RX that the value of the coupling coefficient k is outside the second threshold range and requests the execution of the first control. In F1514, the TX or RX performs the first control.

[0176] In the example of Figure 18, the received power value of RX measured by the power loss method and the Q-factor value measured by the Q-factor measurement method are within their respective threshold ranges, so there is little possibility that a foreign object has entered between the transmitting antenna and the receiving antenna. On the other hand, the value of the coupling coefficient k obtained by the coupling state measurement method for the transmitting antenna and the receiving antenna is outside the threshold range, so there is a possibility that a misalignment has occurred between the transmitting antenna and the receiving antenna. Therefore, in F1514, the first control, i.e., control to deal with the misalignment between the transmitting antenna and the receiving antenna, is performed.

[0177] Next, an example of Fig. 19 will be described. F1515, which is different from Fig. 18, will be described. After F1502, the process proceeds to F1515. In F1515, TX compares the received power value included in RP0 received from RX with a threshold value and performs status detection based on the Power Loss method. Here, it is assumed that the received power value is outside the threshold range, and the status detection result is "possibly abnormal" or "abnormal."

[0178] In the example of Figure 19, the Q-factor value is within the first threshold range, so there is little possibility that a foreign object has entered between the transmitting antenna and the receiving antenna. On the other hand, the RX received power value in the power loss method and the value of the coupling coefficient k in the coupling state measurement method between the transmitting antenna and the receiving antenna are outside their respective threshold ranges, so there is a possibility that a misalignment has occurred between the transmitting antenna and the receiving antenna. Therefore, the first control is performed in F1514.

[0179] As described above, the power loss method and the coupling state measurement method, which can detect misalignment between the transmitting and receiving antennas, each determine that the measured value is outside the threshold range. Compared to the example in Figure 18, it is determined with a higher probability that misalignment between the transmitting and receiving antennas has occurred. Alternatively, the determination result is that "there is a high possibility that misalignment between the transmitting and receiving antennas has occurred."

[0180] Next, an example in Figure 20 will be described. Differences from Figure 19, F1517, F1518, and F1519, will be described. After F1508, the process proceeds to F1517. At F1517, the TX determines that the Q-factor value is outside the first threshold range. After F1517, the process proceeds to F1512 and then to F1518. At F1518, the TX notifies the RX of a request to execute the second control. After F1518, at F1519, the TX or RX executes the second control. In the example of Figure 20, the power loss method and coupling state measurement method, which can detect misalignment between the power transmitting antenna and the power receiving antenna, each determine that the measured value is outside the threshold range. In other words, in the three methods that can detect if a foreign object (metal piece, etc.) has been introduced between the TX and RX, all the measured values ​​are outside the threshold range. This indicates that "a foreign object is present" or "there is a high possibility that a foreign object is present." Therefore, in F1518, the TX notifies the RX of a request to execute the second control. In F1519, the second control, i.e., control to deal with the presence of a foreign object between the power transmitting antenna and the power receiving antenna, is performed.

[0181] Next, we will explain an example that does not fall under the cases shown in Figures 17 to 20. Assume that the Q-factor value is outside the first threshold range and the coupling coefficient k value is within the second threshold range. In this case, since the Q-factor value is outside the first threshold range, the TX determines that a foreign object may have been introduced onto the transmitting antenna and performs the second control. Alternatively, the TX and RX remeasure the coupling coefficient k and Q-factor.

[0182] Assume that the received power value of the RX is within the threshold range, the Q-factor value is outside the first threshold range, and the coupling coefficient k value is outside the second threshold range. In this case, the TX determines that a foreign object may have entered the transmitting antenna, and performs the second control. Alternatively, the TX and RX remeasure the coupling coefficient k and Q-factor.

[0183] Assume that the received power value of the RX is outside the threshold range, the Q-factor value is within the first threshold range, and the coupling coefficient k value is within the second threshold range. In this case, the TX determines that there may be a foreign object on the transmitting antenna or that there may be a misalignment between the transmitting antenna and the receiving antenna. The TX performs the first or second control, or both the first and second controls. Alternatively, the TX and RX remeasure the coupling coefficient k and Q-factor.

[0184] Figures 21 to 23 are flowcharts explaining an example of operation in this embodiment. Figures 21 and 22 are flowcharts explaining the operation of TX in this embodiment. Figure 23 is a flowchart explaining the operation of RX in this embodiment.

[0185] In Fig. 21, after the start of power transmission, in S2101, TX receives information on the received power voltage value from RX, and in S2102 performs the Power Loss method. Next, in S2103, TX determines whether the received power voltage value of RX is within the threshold range. If it is determined that the received power voltage value of RX is within the threshold range, the process proceeds to S2104. If it is determined that the received power voltage value of RX is not within the threshold range, the process proceeds to S2201 in Fig. 22.

[0186] In S2104, the TX measures the Q-factor. In S2105, the TX measures the voltage value. In S2106, the TX receives information necessary to calculate the coupling coefficient k from the RX. In S2107, the TX calculates the value of the coupling coefficient k. Then, in S2108, the TX determines whether the measured value of the Q-factor satisfies the first condition (the measured value is within the first threshold range). If the first condition is satisfied, the process proceeds to S2109, and if the first condition is not satisfied, the process proceeds to S2110.

[0187] In S2109, the TX determines whether the value of the coupling coefficient k satisfies the second condition (the k value is within the second threshold range). If the second condition is satisfied, the process proceeds to S2111, and if the second condition is not satisfied, the process proceeds to S2112. In S2112, the TX continues transmitting power to the RX. Also, in S2112, the TX performs the first control.

[0188] In S2110, the TX determines whether the value of the coupling coefficient k satisfies a second condition. If the second condition is satisfied, the process proceeds to S2113, and if the second condition is not satisfied, the process proceeds to S2114. In S2113 and S2114, the second control is performed, or the coupling coefficient k and the Q-factor are remeasured. For example, the second control is performed in S2113, and the coupling coefficient k and the Q-factor are remeasured in S2114.

[0189] Next, the case where the process moves from S2103 in Fig. 21 to S2201 in Fig. 22 will be described. In S2201, the TX determines whether the measured value of the Q-factor satisfies the first condition. If the first condition is satisfied, the process proceeds to S2202, and if the first condition is not satisfied, the process proceeds to S2203.

[0190] In S2202, the TX determines whether the value of the coupling coefficient k satisfies the second condition. If the second condition is satisfied, the process proceeds to S2204, and if the second condition is not satisfied, the process proceeds to S2205. In S2204, the TX performs the first control, or performs the second control, or remeasures the coupling coefficient k and Q-factor. In addition, in S2205, the TX performs the first control.

[0191] In S2203, the TX determines whether the value of the coupling coefficient k satisfies the second condition. If the second condition is satisfied, the process proceeds to S2206, and if the second condition is not satisfied, the process proceeds to S2207. In S2206, the TX performs the second control or remeasures the coupling coefficient k and Q-factor. In addition, in S2207, the TX performs the second control.

[0192] On the other hand, in Fig. 23, after power reception starts, RX measures the received power value in S2301, and transmits information about the received power value to TX in S2302. In S2303, RX measures the voltage value, and transmits information necessary for calculating the coupling coefficient k to TX in S2304. Then, the process proceeds to S2305. In S2305 to S2308, RX performs control in response to an execution request from TX. The processes of S2305 to S2308 are the same as the processes of S1604 to S1607 in Fig. 16, and therefore will not be described here.

[0193] In this embodiment, by combining the measurement results based on the three methods during power transmission from TX to RX, it is possible to improve the accuracy of judgment regarding state detection, and more appropriate control can be performed based on multiple judgment results.

[0194] [Modified embodiment] Modifications of the above embodiment will now be described. In a first modified embodiment of the first embodiment, the states of the TX and RX are detected by a method for measuring the coupling state of the power transmitting and power receiving antennas without considering the results of the Q-factor measurement method, and the TX and RX perform control according to the detection results. For example, if the value of the coupling state index measured by the coupling state measurement method is within a predetermined threshold range, the TX performs control to continue power transmission. On the other hand, if the value of the coupling state index is outside the predetermined threshold range, the TX or RX performs a first or second control.

[0195] The first control is performed when there is a high possibility of misalignment between the power transmitting antenna and the power receiving antenna. The second control is performed when there is a high possibility of a foreign object being present between the power transmitting antenna and the power receiving antenna. For example, the fifth control is performed in the first control, and the second control is performed in the second control. By performing different control operations in the first control and the second control, appropriate control according to the situation becomes possible.

[0196] Furthermore, although the first control has been described as consisting of the first to fifth control contents, it is possible to combine a plurality of the five control contents. For example, TX and RX are implemented by combining the first control content and the second control content in the first control. The second control can also be implemented by combining a plurality of the first to fifth control contents.

[0197] In a second modified embodiment of the second embodiment, if the measurement result of the received power value using the power loss method among the three methods is within a threshold range, for example, the status of TX and RX is determined to be normal. In this case, the waveform attenuation method and the method for measuring the coupling state of the transmitting antenna and the receiving antenna are not performed. On the other hand, if the measurement result of the received power value using the power loss method is outside the threshold range, it is determined that the status of TX and RX "may be abnormal." Then, because the waveform attenuation method and the coupling state measurement method are performed, status detection can be performed with higher accuracy.

[0198] In a second modified embodiment, measurements are performed based on three methods during power transmission, and TX and RX are controlled according to the measurement results. In this case, the measurement results using the waveform attenuation method are not taken into consideration, and the remaining two methods are used to detect the TX and RX states, and TX and RX are controlled according to the state detection results. For example, if the measurement result using the power loss method is within a threshold range and the measurement result using the coupling state measurement method is also within a threshold range, TX continues power transmission. If the measurement result using either the power loss method or the coupling state measurement method is outside the threshold range, TX or RX performs the first or second control. If the measurement results using both the power loss method and the coupling state measurement method are outside their respective threshold ranges, TX or RX performs the first or second control.

[0199] Furthermore, when only the coupling state measurement method is used without taking into account the measurement results of the power loss method and the waveform attenuation method, the TX and RX are controlled according to the state detection results of the TX and RX. For example, if the measurement result of the coupling state measurement method is within the threshold range, the TX continues to transmit power. If the measurement result of the coupling state measurement method is outside the threshold range, the TX or RX performs the first or second control.

[0200] In a second modified embodiment, measurements are performed using three methods, and if the measurement result using any of the methods falls outside the threshold range, the TX stops transmitting power to the RX and performs CAL processing. In the first or second control, any combination of CAL processing using the power loss method, CAL processing using the waveform attenuation method, and CAL processing using the coupling state measurement method can be performed. Alternatively, three CAL processing methods may be performed.

[0201] Some (or in some cases all) of the configurations in the above embodiments may be replaced with other configurations that perform similar functions, or may be omitted, or other configurations may be added. Furthermore, the present invention is not limited by the WPC standard and can be applied to other systems that use electromagnetic induction, magnetic field resonance, electric field resonance, microwaves, lasers, etc.

[0202] In the above embodiment, multiple detection methods are implemented to detect the states of the transmitting antenna and the receiving antenna, and measurement results of an index representing the quality factor of the transmitting antenna or the attenuation state of the transmitting wave and an index representing the electromagnetic coupling state of both antennas are obtained. A first control can be performed to deal with misalignment of the two antennas, and a second control can be performed to deal with objects that may affect wireless power transmission.

[0203] The power transmitting device and the power receiving device may be, for example, an image input device such as an imaging device (such as a camera or a video camera) or a scanner, or an image output device such as a printer, a copier, a projector, etc. Furthermore, they may be storage devices such as a hard disk drive or a memory device, or information processing devices such as a personal computer (PC) or a smartphone.

[0204] The power receiving device of the present disclosure may also be an information terminal device. For example, the information terminal device has a display unit (display) that receives power from a power receiving antenna and displays information to a user. The power received from the power receiving antenna is stored in a power storage unit (battery), and power is supplied from the battery to the display unit. In this case, the power receiving device may have a communication unit that communicates with other devices different from the power transmitting device. The communication unit may be compatible with communication standards such as NFC communication and the fifth generation mobile communication system (5G).

[0205] The power receiving device of the present disclosure may also be a vehicle such as an automobile. For example, the automobile serving as the power receiving device may receive power from a charger (power transmitting device) via a power transmitting antenna installed in a parking lot. The automobile serving as the power receiving device may also receive power from the charger (power transmitting device) via a power transmitting antenna embedded in the road. In such an automobile, the received power is supplied to a battery. The battery power may be supplied to a driving unit (motor, electric unit) that drives the wheels, or may be used to drive a sensor used for driving assistance or a communication unit that communicates with an external device. In other words, in this case, the power receiving device may include, in addition to the wheels, a battery, a motor or sensor that is driven using the received power, and a communication unit that communicates with devices other than the power transmitting device. Furthermore, the power receiving device may have a storage unit for accommodating a person. For example, the sensor may be a sensor used to measure the distance between vehicles or the distance to other obstacles. The communication unit may be compatible with, for example, a global positioning system (Global Positioning Satellite, GPS). The communication unit may be compatible with communication standards such as the fifth generation mobile communication system (5G), etc. The vehicle may be a bicycle or a motorcycle.

[0206] The power receiving device of the present disclosure may also be an electric tool, a home appliance, or the like. These devices, which are power receiving devices, may have a battery and a motor that is driven by the received power stored in the battery. These devices may also have a notification means for notifying the remaining battery charge, etc. These devices may also have a communication unit that communicates with other devices different from the power transmitting device. The communication unit may be compatible with communication standards such as NFC and the fifth generation mobile communication system (5G).

[0207] The power transmitting device of the present disclosure may also be an on-board charger that transmits power to a mobile information terminal device, such as a smartphone or tablet, that supports wireless power transmission within the vehicle. Such an on-board charger may be installed anywhere within the vehicle. For example, the on-board charger may be installed in the console of the vehicle, on the instrument panel (instrument panel, dashboard), between passenger seats, on the ceiling, or in the door. However, it is preferable that the on-board charger not be installed in a location that interferes with driving. Furthermore, although the power transmitting device has been described using the example of an on-board charger, such a charger is not limited to being installed in a vehicle, but may also be installed in transportation such as a train, airplane, or ship. In this case, the charger may also be installed between passenger seats, on the ceiling, or in the door.

[0208] The power transmitting device may also be a vehicle such as an automobile equipped with an on-board charger. In this case, the power transmitting device has wheels and a battery, and supplies power to the power receiving device via a power transmitting circuit unit and a power transmitting antenna using power from the battery.

[0209] Embodiments of the present disclosure include the following configurations, methods, and programs. (Configuration 1) power transmitting means for transmitting power to a power receiving device via a power transmitting antenna; a measuring means for measuring a first index representing a quality factor of the power transmitting antenna or an attenuation state of a transmitted wave, and a second index representing an electromagnetic coupling state between the power transmitting antenna and a power receiving antenna of the power receiving device; a control means for acquiring the measurement result of the measurement means and controlling the power transmitting means, The control means compares the measured first and second indicators with respective thresholds; performing a first control to address a positional misalignment between the power transmitting antenna and the power receiving antenna when the measurement result of the first index satisfies a first condition that the measurement result of the first index is within a first range and the measurement result of the second index does not satisfy a second condition that the measurement result of the second index is within a second range; If the measurement result of the first index does not satisfy the first condition and the measurement result of the second index does not satisfy the second condition, a second control is performed to deal with the presence of an object other than the power receiving device between the power transmitting antenna and the power receiving antenna. A power transmission device characterized by: (Configuration 2) The control means performs control to start or continue power transmission to the power receiving device when the measurement result satisfies the first and second conditions. 2. The power transmitting device according to configuration 1, (Configuration 3) a communication means for communicating with the power receiving device; As the first control, the control means controls the communication means to transmit to the power receiving device a transmission request requesting that the power receiving device transmit a notification request of a power transmission limit to the power transmitting device. 3. The power transmitting device according to configuration 1 or 2. (Configuration 4) a communication means for communicating with the power receiving device; The control means performs control, as the first control, to transmit to the power receiving device, via the communication means, a request for notification processing to prompt the power transmitting device to rearrange the power receiving device. 3. The power transmitting device according to configuration 1 or 2. (Configuration 5) The control means performs the first control by adjusting the position or attitude of the power transmitting antenna relative to the power receiving antenna. 3. The power transmitting device according to configuration 1 or 2. (Configuration 6) a communication means for communicating with the power receiving device; The control means performs control to transmit, as the first control, a control request for adjusting the position or attitude of the power receiving antenna relative to the power transmitting antenna to the power receiving device via the communication means. 3. The power transmitting device according to configuration 1 or 2. (Configuration 7) The control means performs control to change a frequency band used for power transmission as the first control. 3. The power transmitting device according to configuration 1 or 2. (Configuration 8) a communication means for communicating with the power receiving device; As the second control, the control means controls the communication means to transmit to the power receiving device a transmission request requesting that the power receiving device transmit a notification request of a power transmission limit to the power transmitting device. 3. The power transmitting device according to configuration 1 or 2. (Configuration 9) a communication means for communicating with the power receiving device; As the second control, the control means controls the communication means to transmit to the power receiving device a request for notification processing to prompt removal of an object different from the power receiving device. 3. The power transmitting device according to configuration 1 or 2. (Configuration 10) The control means performs control to change a frequency band used for power transmission as the second control. 3. The power transmitting device according to configuration 1 or 2. (Configuration 11) a detection means for detecting a temperature in the vicinity of the power transmitting antenna, As the second control, the control means acquires temperature detection information from the detection means, and when a value of the temperature detection information is greater than a threshold, controls to limit power transmission to the power receiving device or reset an operating state. 3. The power transmitting device according to configuration 1 or 2. (Configuration 12) When the measurement result of the first index does not satisfy the first condition and the measurement result of the second index satisfies the second condition, the control means performs the second control or controls remeasurement by the measurement means. 12. The power transmitting device according to any one of configurations 1 to 11. (Configuration 13) a communication means for communicating with the power receiving device; When the received power value acquired from the power receiving device by the communication means is within a range based on a threshold, the control means performs the first control when it is determined that the measurement result of the first index satisfies the first condition and the measurement result of the second index does not satisfy the second condition, and performs the second control when it is determined that the measurement result of the first index does not satisfy the first condition, or controls re-measurement by the measurement means. 13. The power transmitting device according to any one of configurations 1 to 12. (Configuration 14) When the received power value acquired from the power receiving device by the communication means is not within a range based on a threshold, the control means performs the first or second control when it determines that the measurement result satisfies the first and second conditions, or controls re-measurement by the measurement means. 14. The power transmitting device according to configuration 13. (Configuration 15) When the received power value acquired from the power receiving device by the communication means is not within a range based on a threshold, the control means performs the second control or controls re-measurement by the measurement means when it is determined that the measurement result of the first index does not satisfy the first condition and the measurement result of the second index satisfies the second condition. 15. The power transmitting device according to configuration 14. (Configuration 16) The control means determines a power value guaranteed when the power receiving device receives power from the power transmitting device through negotiation between the power transmitting device and the power receiving device in the first or second control. 16. The power transmitting device according to any one of configurations 1 to 15. (Configuration 17) A power receiving device that configures a wireless power transmission system together with the power transmitting device according to any one of configurations 1 to 16, a communication means for communicating with the power transmitting device; and a control unit that controls the communication unit to transmit the information used for the measurement to the power transmitting device. A power receiving device characterized by: (Configuration 18) When a transmission request related to a notification request for limiting power transmission is received from the power transmitting device under the first control, the control means included in the power receiving device performs control to transmit the notification request for limiting power transmission to the power transmitting device. 18. The power receiving device according to configuration 17. (Configuration 19) an output unit that outputs a notification to prompt the power receiving device to rearrange with respect to the power transmitting device under the first control; 19. The power receiving device according to configuration 17 or 18. (Configuration 20) The control means of the power receiving device performs the first control to adjust the position or attitude of the power receiving antenna relative to the power transmitting antenna. 18. The power receiving device according to configuration 17. (Configuration 21) and an output means for issuing a notification urging the removal of the object under the second control. 21. The power receiving device according to any one of configurations 17 to 20. (Configuration 22) A charging unit is provided to charge a battery using the power received from the power transmitting device. 22. The power receiving device according to any one of configurations 17 to 21. (Method 1) A method for controlling wireless power transmission, which is executed by a power transmitting device that transmits power to a power receiving device using a power transmitting antenna, comprising: a measuring step of measuring a first index representing a quality factor of the power transmitting antenna or an attenuation state of a transmitted wave, and a second index representing an electromagnetic coupling state between the power transmitting antenna and a power receiving antenna of the power receiving device; a control step in which a control means acquires the measurement result of the measurement step and controls the power transmission, In the control step, the control means compares the measured first and second indicators with respective threshold values; performing a first control to deal with a positional misalignment between the power transmitting antenna and the power receiving antenna when the measurement result of the first index satisfies a first condition that the measurement result of the first index is within a first range and when the measurement result of the second index does not satisfy a second condition that the measurement result of the second index is within a second range; If the measurement result of the first index does not satisfy the first condition and the measurement result of the second index does not satisfy the second condition, a second control is performed to deal with the presence of an object other than the power receiving device between the power transmitting antenna and the power receiving antenna. A method for controlling wireless power transmission. (program) A computer is caused to execute each step of method 1. A program characterized by:

[0210] [Other embodiments] The present disclosure can also be realized by providing 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.

[0211] 15, 16, 21 to 23 may be realized by hardware. In the case of hardware realization, for example, a predetermined compiler may be used to automatically generate a dedicated circuit on an FPGA from a program for realizing each step. Also, a gate array circuit may be formed in the same manner as an FPGA and realized as hardware. [Explanation of symbols]

[0212] 100 Power transmission device 200 Powered Device

Claims

1. A power receiving means for wirelessly receiving power from a power transmitting device; A receiving means for receiving, from the power transmitting device, first information relating to a voltage of an inverter included in the power transmitting device; a transmitting means for transmitting a specific signal for causing the power transmitting device to limit a voltage of the inverter in response to second information determined based on the first information.

2. A power receiving device as described in claim 1, further having a setting means for setting the maximum power value that can be received by the power receiving device to 5 W in accordance with second information determined based on the first information.

3. The power receiving device described in claim 1, wherein the second information is determined based on the first information and third information regarding a rectified voltage in the power receiving device.

4. A power receiving device as described in Claim 3, wherein the third information is information regarding the output voltage of a rectifier possessed by the power receiving device.

5. The power receiving device described in Claim 3, wherein the third information is information regarding the output voltage of a rectifier possessed by the power receiving device measured under a light load condition.

6. The power receiving device as described in claim 1, wherein the first information is information regarding the voltage of the inverter measured under a light load condition.

7. The second information is determined based on a plurality of calculations of a specific index, The power receiving device according to claim 1 , wherein the specific index is calculated based on the first information.

8. A power receiving process for wirelessly receiving power from a power transmitting device; a receiving step of receiving, from the power transmitting device, first information related to a voltage of an inverter included in the power transmitting device; A method performed by a power receiving device, comprising: a transmitting step of transmitting a specific signal to the power transmitting device to limit the voltage of the inverter in accordance with second information determined based on the first information.

9. The method according to claim 8, further comprising a setting step of setting the maximum power value that can be received by the power receiving device to 5 W in accordance with second information determined based on the first information.

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