Power receiving device, power transmitting device, wireless power transmission system, communication method, wireless power transmission method, and computer program

Abstract

In the present invention, a power receiving device (200) in a wireless power transmission system transmits a request for changing a power transmission output with respect to a power transmitting device (100) when a target power is set (S1403). The request for changing the power transfer output includes difference information indicating a difference between a current operating point and a target operating point of the powered device (200). The power receiving device (200) determines whether or not a request for change including difference information greater than a predetermined threshold value is transmitted to the power receiving device (100) a predetermined number of times or more or is continuously transmitted to the power receiving device (100) for a predetermined time or more (S1407, S1408). The power receiving device (200) transmits, to the power transmitting device (100), a request for changing power transmission control, such as control to stop or limit power transmission, in accordance with the determination result.

Description

Technical Field

[0001] The present disclosure relates to a power receiving device, a power transmitting device, a wireless power transmission system, a communication method, a wireless power transmission method, and a computer program. Background Art

[0002] In a wireless power transmission system, it is necessary to detect whether an object other than the power receiving device (hereinafter also referred to as a foreign object) is present between the power transmitting device and the power receiving device. In a wireless power transmission system, error handling may have to be performed in cases other than the placement of a foreign object. For example, countermeasures may be required for a failure of the power transmitting device or the power receiving device, and misalignment between the power transmitting device and the power receiving device. Summary of the invention

[0003] Problem that the invention aims to solve

[0004] In a wireless power transmission system according to the related art, it is difficult to determine whether a system error during power transmission is due to the placement of a foreign object, due to a device failure, or due to an erroneous detection in a foreign object detection process. Therefore, in a case where power is actually being safely transmitted from a power transmitting device to a power receiving device but power transmission is stopped due to the occurrence of a system error, appropriate power transmission control may not be performed.

[0005] An object of the present disclosure is to provide a technology that can enable power transmission control that is adaptive to the state of a wireless power transmission system.

[0006] Solutions for solving problems

[0007] According to an embodiment of the present disclosure, there is provided a power receiving device, comprising: a power receiving component configured to wirelessly receive power from a power transmitting device; a communication component configured to communicate with the power transmitting device; and a control component configured to perform control for sending, via the communication component, a first request for changing or maintaining a power transmission output for the power transmitting device, wherein, in a case where the first request for increasing the power transmission output of the power transmitting device has been sent to the power transmitting device a predetermined number of times or more or has been continuously sent to the power transmitting device for a predetermined time or longer, the control component performs control for sending, via the communication component, a second request for changing power transmission control to the power transmitting device.

[0008] Effects of the Invention

[0009] According to the present disclosure, it is possible to provide a technology that enables power transmission control that is adapted to the state of the wireless power transmission system. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1is a diagram illustrating an example of a structure of a wireless power transmission system.

[0011] Figure 2 It is a diagram illustrating an example of the configuration of a power transmission device.

[0012] Figure 3 It is a diagram illustrating an example of the configuration of a power receiving device.

[0013] Figure 4 The diagram exemplifies a threshold setting method in state detection based on power loss.

[0014] Figure 5 : is a block diagram illustrating an example of a functional configuration of a control unit of a power transmission device.

[0015] Figure 6 : is a block diagram illustrating an example of a functional configuration of a control unit of a power receiving device.

[0016] Figure 7 is a sequence diagram illustrating an example of processing in wireless power transmission.

[0017] Figure 8 This is a diagram illustrating state detection using a waveform decay method.

[0018] Fig. 9 This is a diagram illustrating a threshold setting method in state detection using a waveform decay method.

[0019] Fig.10 (A) and (B) are diagrams illustrating a method of measuring a coupling state between a power transmitting antenna and a power receiving antenna.

[0020] Fig.11 This is a diagram illustrating a threshold setting method in state detection using the coupled state measurement method.

[0021] Fig.12 (A) and (B) are graphs illustrating a Q factor measurement method.

[0022] Fig.13 is a sequence diagram illustrating an example of the operation according to the first embodiment.

[0023] Fig.14 is a flowchart illustrating operations performed by the power receiving device according to the first embodiment.

[0024] Fig.15 is a sequence diagram illustrating another example of the operation according to the first embodiment.

[0025] Fig.16 is a flowchart illustrating another example of the operation performed by the power receiving device according to the first embodiment.

[0026] Fig.17is a sequence diagram illustrating an example of an operation according to a modification example.

[0027] Fig.18 is a flowchart illustrating an example of an operation performed by a power receiving device according to a modification.

[0028] Fig.19 is a sequence diagram illustrating another example of the operation according to the modification example.

[0029] Fig. 20 is a flowchart illustrating another example of the operation performed by the power receiving device according to the modification.

[0030] Fig.21 is a sequence diagram illustrating a first example of the operation according to the second embodiment.

[0031] Fig. 22 is a sequence diagram illustrating a second example of the operation according to the second embodiment.

[0032] Fig.23 is a sequence diagram illustrating a third example of the operation according to the second embodiment.

[0033] Fig.24 is a sequence diagram illustrating a fourth example of the operation according to the second embodiment.

[0034] Fig.25 is a sequence diagram illustrating a fifth example of the operation according to the second embodiment.

[0035] Fig.26 is a sequence diagram illustrating a sixth example of the operation according to the second embodiment.

[0036] Fig. 27 is a sequence diagram illustrating a seventh example of the operation according to the second embodiment.

[0037] Fig.28 is a sequence diagram illustrating an eighth example of the operation according to the second embodiment.

[0038] Fig.29 is a flowchart illustrating operations performed by the power receiving device according to the second embodiment.

[0039] Fig.30 is exemplified in Fig.29 Flowchart of subsequent processing.

[0040] Fig.31 is a flowchart illustrating operations performed by the power transmitting device according to the second embodiment.

[0041] Fig.32 is exemplified in Fig.31 Flowchart of subsequent processing. DETAILED DESCRIPTION

[0042] Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In the embodiments, a wireless charging system to which a wireless power transmission system is applied will be described. For example, wireless power transmission based on a standard defined by the Wireless Power Consortium, which is a wireless charging standardization organization (hereinafter referred to as the WPC standard), will be described.

[0043] [First embodiment]

[0044] The following will refer to Figures 1 to 17 The first embodiment will be described. Figure 1 1 is a diagram illustrating an example of the structure of a wireless charging system. The system includes a power transmitting device 100, a power receiving device 200, and a charging stand 300. In the following description, for the purpose of simplifying the description, the power receiving device 200 may be referred to as RX and the power transmitting device 100 may be referred to as TX. Figure 2 and Figure 3 To illustrate the detailed structure of TX and RX.

[0045] RX is an electronic device that receives power from TX and charges the built-in battery when it is placed on the charging stand 300. TX is an electronic device that wirelessly transmits power to RX placed on the charging stand 300. Since the charging stand 300 constitutes a part of TX, in the following description, RX "placed on the charging stand 300" may be referred to as "placed on TX". The spatial range in which RX can receive power from TX is determined by Figure 1 The scope of the dashed box 400 in FIG.

[0046] In addition to the wireless charging function, the RX and TX may also have the function of executing applications. For example, the RX is a smart phone and the TX is an accessory device for charging the battery of the RX.

[0047] RX and TX are not limited to this example, and may be a tablet device, a storage device such as a hard disk device or a memory device, or an information processing device such as a personal computer (PC). RX and TX may be an imaging device such as a still camera or a video camera, a car, a robot, a medical device, or a printer, etc.

[0048] The following will refer to Figure 2 An example of the configuration of the power transmission device 100 will be described. Figure 2 1 is a functional block diagram illustrating an example of the structure of a power transmission device 100 (TX). TX includes a control unit 101, a power supply unit 102, a power transmission unit 103, a first communication unit 104, a power transmission antenna 105, a memory 106, a resonant capacitor 107, a switch unit 108, and a second communication unit 109. Figure 2In the embodiment, each functional block is illustrated as a separate unit, but a plurality of functional blocks may be mounted in a single chip.

[0049] The control unit 101 controls the entire TX by executing a control program stored in the memory 106. The control unit 101 performs power transmission control including communication for device authentication in TX. In addition to wireless power transmission, the control unit 101 can also perform control for executing applications.

[0050] The control unit 101 includes one or more processors such as a central processing unit (CPU) or a microprocessor unit (MPU), etc. Alternatively, the control unit 101 may be constituted by hardware such as an application specific integrated circuit (ASIC), etc.

[0051] The control unit 101 may include an array circuit such as a field programmable gate array (FPGA) configured to perform predetermined processing. The control unit 101 may perform processing of storing information to be stored during execution of various processing in the memory 106 or timing processing using a timer (not illustrated).

[0052] The power supply unit 102 supplies power to each functional block element. The power supply unit 102 includes, for example, a power connection circuit for a commercial power source or a battery. The battery is charged with power supplied from the commercial power source.

[0053] The power transmission unit 103 generates electromagnetic waves for causing the RX to receive power by converting DC power or AC power input from the power supply unit 102 into AC power in a frequency band used for wireless power transmission and inputting the AC power to the power transmission antenna 105 .

[0054] For example, the power transmission 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 having a half-bridge structure or a full-bridge structure. The power transmission unit 103 includes a plurality of field effect transistors (FETs) forming a bridge and a gate driver for controlling ON / OFF of the plurality of FETs.

[0055] The power transmission unit 103 controls the intensity of electromagnetic waves to be output by adjusting the voltage (power transmission voltage) or current (power transmission current) or both input to the power transmission antenna 105. The intensity of the electromagnetic waves is controlled based on the magnitude of the power transmission voltage or the power transmission current.

[0056] In the power transmission unit 103, the output control of the power having the AC frequency is performed based on the command signal from the control unit 101, so as to control the start or stop of the power transmission from the power transmission antenna 105 or the intensity of the electromagnetic wave to be output. Assume that the power transmission unit 103 has a charging unit ( Figure 3 :206) Power supply capability to output 15 watts (W) of electricity.

[0057] The first communication unit 104 is connected to the control unit 101 and the power transmission unit 103, and performs communication for power transmission control based on the WPC standard with respect to the RX. The first communication unit 104 performs frequency shift modulation of electromagnetic waves output from the power transmission antenna 105, and transmits information to the RX to communicate with the RX.

[0058] The first communication unit 104 demodulates the electromagnetic wave transmitted from the power transmission antenna 105 and modulated by the RX, and acquires information transmitted from the RX. Communication using the first communication unit 104 is performed by superimposing a communication signal on the electromagnetic wave transmitted from the power transmission antenna 105.

[0059] In addition to storing the control program, the memory 106 can also store information related to the status of TX and RX. The information related to the status of TX and RX includes the power value of the transmitted power and the power value of the received power. The information related to the status of TX is acquired by the control unit 101. The information related to the status of RX is acquired by the control unit ( Figure 3 :201) is obtained and can be received by the first communication unit 104.

[0060] The switch unit 108 is connected in parallel to the series circuit of the resonance capacitor 107 and the power transmission antenna 105. The control unit 101 sends a control signal to the switch unit 108 and controls its ON / OFF. The power transmission antenna 105 is connected to the resonance capacitor 107.

[0061] When the switch unit 108 is turned on by a control signal from the control unit 101 and its circuit is short-circuited, the power transmission antenna 105 and the resonance capacitor 107 form a series resonance circuit and resonate at a specific frequency f1. At this time, current flows in a closed circuit formed by the power transmission antenna 105, the resonance capacitor 107 and the switch unit 108.

[0062] On the other hand, when the switch unit 108 is turned off by a control signal from the control unit 101 and its circuit is open, power is supplied from the power transmission unit 103 to the power transmission antenna 105 and the resonance capacitor 107 .

[0063] The second communication unit 109 is connected to the control unit 101 and communicates with the RX based on a standard different from the WPC standard. For example, the second communication unit 109 uses an antenna different from the power transmission antenna 105 to communicate with the RX ( Figure 3 The second communication unit 212 in the communication module communicates with the controller.

[0064] Examples of the communication network include a wireless local area network (LAN), Bluetooth (registered trademark) low energy (BLE), and near field communication (NFC).

[0065] Regarding the communication between TX and RX, TX can selectively use one of a plurality of communication standards to communicate with RX. It is possible to selectively use a communication mode of a plurality of types of communication as will be described below.

[0066] - In the first communication unit 104 of TX and the first communication unit 204 of RX ( Figure 3 ) based on the first standard (WPC standard);

[0067] - In the second communication unit 109 of TX and the second communication unit 212 of RX ( Figure 3 ) based on a second standard (a standard other than the WPC standard).

[0068] The following will refer to Figure 3 An example of the configuration of the power receiving device 200 will be described. Figure 3 RX includes 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.

[0069] RX additionally includes 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. In this embodiment, it is assumed that Figure 3 The illustrated functional blocks are separate elements, but multiple functional blocks may also be implemented as a single hardware module.

[0070] The voltage between the power reception unit 203 and the charging unit 206 (refer to the dotted arrow 214) indicates a voltage value output from a rectifying unit (rectifier) ​​provided in the power reception unit 203. In the following description, this voltage value is referred to as "Vrect".

[0071] The control unit 201 controls each functional block of the RX by executing a control program stored in the memory 208. The control unit 201 may perform control for executing an application other than wireless power transmission.

[0072] The control unit 201 includes one or more processors such as a CPU or an MPU, etc. The entire RX (for example, the entire smartphone) can be controlled by cooperating with an operating system (OS) executed by the control unit 201 .

[0073] Alternatively, the control unit 201 is composed of hardware such as ASIC, or is composed of an array circuit such as FPGA configured to perform predetermined processing. The control unit 201 can store information to be stored during the execution of various processes in the memory 208, and perform timing processing using a timer (not illustrated).

[0074] The UI unit 202 is connected to the control unit 201 and outputs various types of information to the user. The output of various types of information includes operations such as screen display, flashing or color change of a light emitting diode (LED), output of a voice from a speaker, and vibration of the main body of the RX. The UI unit 202 is implemented by a liquid crystal panel, a speaker, a vibration motor, and the like.

[0075] The power receiving unit 203 acquires AC power (AC voltage and AC current) generated by electromagnetic induction based on electromagnetic waves emitted from the TX power transmitting antenna 105 via the power receiving antenna 205. The power receiving unit 203 converts the AC power into DC or AC power of a predetermined frequency and supplies the power to the charging unit 206.

[0076] The charging unit 206 charges the battery 207. The power receiving unit 203 includes a rectifying unit (rectifier) ​​and a voltage control unit required to supply power to the load in RX. The power receiving unit 203 supplies charging power from the charging unit 206 to the battery 207. It is assumed that the power receiving unit 203 has a power supply capability capable of outputting 15 watts of power to the charging unit 206.

[0077] The first communication unit 204 performs communication for power reception control based on the WPC standard with respect to the first communication unit 104 of TX. The first communication unit 204 is connected to the power reception antenna 205 and the control unit 201 .

[0078] The first communication unit 204 demodulates the electromagnetic wave input from the power receiving antenna 205 and acquires information transmitted from TX. The first communication unit 204 communicates with TX by load modulating or amplitude modulating the input electromagnetic wave and superimposing a signal associated with information to be transmitted to TX on the electromagnetic wave.

[0079] In addition to storing the control program, the memory 208 also stores information related to the status of TX and RX. The information related to the status of RX is acquired by the control unit 201. The information related to the status of TX can be acquired by the control unit 101 of TX and can be received by the first communication unit 204 or the second communication unit 212.

[0080] The first switch unit 209 is provided between the charging unit 206 and the battery 207 and is controlled by the control unit 201. The first switch unit 209 has a function for controlling whether to supply the power received by the power receiving unit 203 to the battery 207 and a function for controlling the load amount.

[0081] When the first switch unit 209 is turned off by the control unit 201 and its circuit is open, the power received by the power receiving unit 203 is not supplied to the battery 207. When the first switch unit 209 is turned on by the control unit 201 and its circuit is short-circuited, the power received by the power receiving unit 203 is supplied to the battery 207.

[0082] exist Figure 3 In the illustrated example, the first switch unit 209 is provided between the charging unit 206 and the battery 207 , but the first switch unit 209 may be provided between the power receiving unit 203 and the charging unit 206 .

[0083] Alternatively, the first switch unit 209 may be provided between the closed circuit formed by the power receiving antenna 205, the resonant capacitor 211, and the second switch unit 210 and the power receiving unit 203. In this case, the first switch unit 209 has a function for controlling whether the power received by the power receiving antenna 205 is supplied to the power receiving unit 203.

[0084] exist Figure 3 In the illustrated example, the first switch unit 209 is illustrated as a single functional block, but the first switch unit 209 may be implemented as a part of the charging unit 206 or the power receiving unit 203 .

[0085] The present embodiment is not limited to the structure in which the first switch unit 209 is inserted in series between the charging unit 206 and the battery 207 , and the first switch unit 209 may be inserted in parallel between the charging unit 206 and the battery 207 .

[0086] In this case, when the first switch unit 209 is turned off by the control unit 201 and its circuit is open, the power received by the power receiving unit 203 is supplied to the battery 207. When the first switch unit 209 is turned on by the control unit 201 and its circuit is short-circuited, the power received by the power receiving unit 203 is not supplied to the battery 207.

[0087] On the input side of the power receiving unit 203, the second switch unit 210 is connected in parallel to the resonance capacitor 211. The resonance 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.

[0088] The third switch unit 213 has a function of controlling whether to open the terminal of the power receiving antenna 205. When the third switch unit 213 is turned off by the control unit 201, the terminal of the power receiving antenna 205 is opened. When the third switch unit 213 is turned on by the control unit 201, the power receiving antenna 205 is connected to the power receiving unit 203 via the resonance capacitor 211.

[0089] When the third switch unit 213 is turned on and the second switch unit 210 is turned on by the control unit 201, and the circuit of the third switch unit 213 and the second switch unit 210 is short-circuited, the power receiving antenna 205 and the resonance capacitor 211 form a series resonance circuit and resonate at a specific frequency f2. Current flows in the closed circuit formed by the power receiving antenna 205, the resonance capacitor 211 and the second switch unit 210, and current does not flow in the power receiving unit 203.

[0090] When the second switch unit 210 is turned off and its circuit is open, the power received by the power receiving antenna 205 and the resonance capacitor 211 is supplied to the power receiving unit 203. Figure 3 In the illustrated example, the second switch unit 210 may be provided between the power receiving antenna 205 and the resonance capacitor 211 .

[0091] When the third switch unit 213 is turned on and the second switch unit 210 is turned on, the terminals of the power receiving antenna 205 are short-circuited. The third switch unit 213 may be provided between the resonance capacitor 211 and the power receiving unit 203.

[0092] In this system, TX and RX perform wireless power transmission based on the WPC standard between the power transmitting antenna 105 and the power receiving antenna 205. In the WPC standard, the amount of power guaranteed when the power receiving device 200 receives power from the power transmitting device 100 is defined by a value called guaranteed power (hereinafter referred to as "GP").

[0093] For example, GP represents a power value with which output to the load of the power receiving device 200 is guaranteed even when 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 includes Figure 3 The charging unit 206 and the battery 207 in the power receiving unit 203 are connected, and the value of GP corresponds to the amount of power guaranteed to be output from the power receiving unit 203.

[0094] For example, assume that the value of 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 when the power transmission efficiency decreases, the power transmitting device 100 performs power transmission control so that 5 watts can be output to the load of the power receiving device 200.

[0095] The value of GP is determined by negotiation between the power transmitting apparatus 100 and the power receiving apparatus 200. The present embodiment can be applied to a configuration in which power is transmitted / received using power determined by negotiation between the power transmitting apparatus and the power receiving apparatus in addition to GP.

[0096] When power is transmitted from the power transmission device 100 to the power receiving device 200, it is assumed that an object exists near the power transmission device 100. The object in this case is an object that can affect the power transmission from the power transmission device 100 to the power receiving device 200, and is an object (foreign object) different from the power receiving device 200. The electromagnetic waves used for power transmission can affect the foreign object, and there is a possibility that the foreign object will be heated up or damaged.

[0097] The object in the present disclosure is, for example, a clip or an IC card. Among objects that are indispensable to a power receiving device and a product incorporating the power receiving device or a power transmitting device and a product incorporating the power transmitting device, an object that may unintentionally generate heat when the object is exposed to wireless power transmitted from a power transmitting antenna does not correspond to a foreign object.

[0098] The WPC standard defines a method for suppressing the occurrence of temperature rise or damage of foreign matter by stopping power transmission when foreign matter is present. Specifically, the power transmission device 100 can detect the presence of foreign matter on the charging stand 300. The power loss method is a method for detecting foreign matter based on the difference between the transmitted power in the power transmission device 100 and the received power in the power receiving device 200.

[0099] The Q factor measurement method is a method for detecting foreign matter based on a change in the quality factor (Q factor) of the power transmission antenna 105 (power transmission coil) in the power transmission device 100. Foreign matter detected by the power transmission device 100 is not limited to an object existing on the charging stand 300. The power transmission device 100 can detect foreign matter located near the power transmission device 100. For example, the power transmission device 100 can detect foreign matter located in a power transmittable range.

[0100] The following will refer to Figure 4 This section explains foreign body detection based on the power loss method defined in the WPC standard. Figure 4 , the horizontal axis represents the transmitted power of the power transmitting device 100 , and the vertical axis represents the received power of the power receiving device 200 .

[0101] On the graph indicated by the linear segment 1002, point 1000 corresponds to the first transmission power value Pt1 and the first reception power value Pr1, and point 1001 corresponds to the second transmission power value Pt2 and the second reception power value Pr2. On the graph, point 1003 corresponds to the third transmission power value Pt3 and the third reception power value Pr3. The foreign matter to be detected is a metal piece having conductivity, etc.

[0102] First, the power transmission device 100 transmits power to the power receiving device 200 at the first transmission power value Pt1, and the power receiving device 200 receives power at the first reception power value Pr1. In the following description, this state is referred to as a light load state. Then, the power transmission device 100 stores the first transmission power value Pt1.

[0103] Here, the first transmission power value Pt1 and the first reception power value Pr1 are predetermined minimum transmission power values ​​and minimum reception power values. At this time, the power receiving device 200 performs load control so that the power to be received is minimized. For example, the power receiving device 200 may disconnect the load from the power receiving antenna 205 so that the reception power is not supplied to the load (such as Figure 3 The charging unit 206 and battery 207, etc.)

[0104] This can be achieved by controlling the first switch unit 209. Then, the power receiving device 200 notifies the power transmitting device 100 of the first received power value Pr1. The power transmitting device 100, which receives the signal associated with the first received power value Pr1 from the power receiving device 200, calculates the power loss between the power transmitting device 100 and the power receiving device 200.

[0105] The power loss at this time is Pt1 - Pr1 (= Ploss1 ). A calibration point (hereinafter abbreviated as CP) 1000 indicating the correspondence relationship between Pt1 and Pr1 may be generated.

[0106] Subsequently, the power transmitting device 100 changes the transmission power value to the 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 reception power value Pr2. In the following description, this state is referred to as a load connected state (load connected state).

[0107] Then, the power transmission device 100 stores the second receiving power value Pr2. Here, the second transmission power value Pt2 and the second receiving power value Pr2 are predetermined maximum transmission power values ​​and maximum receiving power values. At this time, the power receiving device 200 performs load control to maximize the received power.

[0108] For example, the power receiving device 200 connects the load to the power receiving antenna 205 so that the received power is supplied to the load. This can be achieved by controlling the first switch unit 209. Subsequently, the power receiving device 200 notifies the power transmitting device 100 of the second received power value Pr2.

[0109] The power transmission device 100 that has received the signal associated with the second received power value Pr2 from the power receiving device 200 calculates the power loss between the power transmission device 100 and the power receiving device 200. The power loss at this time is Pt2-Pr2 (=Ploss2). CP 1001 indicating the correspondence relationship between Pt2 and Pr2 may be generated.

[0110] The power transmission device 100 performs linear interpolation processing between CP 1000 and CP 1001 and generates a line segment 1002. The line segment 1002 represents the relationship between the transmitted power and the received power in a state where no foreign object is detected near the power transmission device 100 and the power reception device 200 (hereinafter referred to as a first detection state).

[0111] The power transmitting device 100 can estimate the power value received by the power receiving device 200 when power is transmitted at a predetermined power transmission power in the first detection state based on the line segment 1002. For example, it is assumed that the power transmitting device 100 transmits power at a third power transmission power value Pt3. In this case, the power transmitting device 100 can estimate the third power transmission power value Pt3 received by the power receiving device 200 based on a point 1003 on the line segment 1002 corresponding to Pt3.

[0112] As described above, the power loss between the power transmitting device 100 and the power receiving device 200 can be calculated for each load based on a plurality of combinations of the transmission power value of the power transmitting device 100 and the reception power value of the power receiving device 200 measured while changing the load. The power loss between the power transmitting device 100 and the power receiving device 200 can be estimated for all loads by interpolation processing based on a plurality of combinations of the transmission power value and the reception power value.

[0113] The calibration process performed by the power transmitting device 100 and the power receiving device 200 so that the power transmitting device 100 obtains a combination of the transmitted power value and the received power value is referred to as “calibration process using the power loss method.” The calibration process is abbreviated as CAL process.

[0114] After performing the CAL process using the power loss method, it is assumed that 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 a signal associated with the reception power value Pr3* from the power receiving device 200. The power transmitting device 100 calculates Pr3-Pr3 by subtracting the reception power value Pr3* actually received from the power receiving device 200 from the reception power value Pr3 in the first detection state.* (=Ploss_FO).

[0115] Ploss_FO can be estimated as the power consumed in the foreign object (that is, power loss) when the foreign object exists near the power transmission device 100 and the power reception device 200. In the following description, the state in which the presence of the foreign object near the power transmission device 100 and the power reception device 200 is detected is referred to as the second detection state.

[0116] In the second detection state, the power transmission device 100 compares the power loss Ploss_FO consumed by the foreign object with a predetermined threshold value. When the value of the power loss Ploss_FO is greater than the threshold value, the power transmission device 100 can determine that there is a foreign object.

[0117] Alternatively, the power transmitting device 100 acquires the third received power value Pr3 in the first detection state from the power receiving device 200 , and calculates the power loss Pt3 −Pr3 (= Ploss3 ) between the power transmitting device 100 and the power receiving device 200 in advance.

[0118] Then, the power transmission device 100 acquires the received power value Pr3* from the power receiving device 200 in the second detection state, and calculates the power loss Pt3-Pr3 between the power transmission device 100 and the power receiving device 200 in the second detection state. * (=Ploss3 * Then, the power transmission device 100 can use Ploss3 * -Ploss3 to estimate the power loss Ploss_FO.

[0119] As described above, there are two methods for calculating Ploss_FO in the second detection state.

[0120] - A first method for calculating Ploss_FO according to Pr3-Pr3*;

[0121] - A second method of calculating Ploss_FO according to Ploss3*-Ploss3.

[0122] In this embodiment, the second method will be basically described, but the details of this embodiment can be applied to the first method.

[0123] The RX and TX in this embodiment perform communication for power transmission and power reception control based on the WPC standard. In the WPC standard, multiple stages are defined, including a power transmission stage in which power transmission is performed, and one or more stages before the actual power transmission. Communication required for power transmission / power reception control is performed in each stage.

[0124] For example, foreign object detection using the power loss method is performed in the power transmission phase based on data acquired in the calibration phase. Foreign object detection using the Q factor measurement method is performed in the phase before power transmission (before sending a digital ping and in the negotiation phase or renegotiation phase).

[0125] The stages before power transfer in the WPC standard include a selection stage, a ping stage, and an identification and configuration stage (configuration stage).

[0126] The phase before power transmission in the WPC standard also includes a negotiation phase and a calibration phase. In the following description, the identification and configuration phase is referred to as the I&C phase. The processing in each phase will be described below.

[0127] In the selection phase, TX intermittently sends a simulated ping and detects that an object is placed on the charging base of TX. For example, it detects that RX or a conductor sheet, etc. is placed on the charging base.

[0128] TX detects one or both of the voltage value and the current value of the power transmission antenna 105 when transmitting the simulated ping. When the voltage value is less than a threshold value or when the current value is greater than a threshold value, TX determines that an object exists and transitions to the ping phase.

[0129] In the ping phase, TX sends a digital ping having a higher power than that of the analog ping. The magnitude of the power of the digital ping is the magnitude of power sufficient to start the control unit of the RX placed on the TX.

[0130] RX notifies TX of the power receiving voltage value. Thus, TX recognizes that the object detected in the selection phase is RX by receiving a response from RX that received the digital ping. When TX is notified of the power receiving voltage value, it transitions to the I&C phase.

[0131] Before sending the digital ping, TX uses, for example, an analog ping to measure the Q factor of the power transmission antenna 105. This measurement result is used to perform foreign object detection processing using the Q factor measurement method.

[0132] In the I&C phase, TX identifies RX and obtains device configuration information (capability information) from RX. RX sends signals of ID packets and configuration packets.

[0133] The ID packet includes the identifier information of the RX, and the configuration packet includes the device configuration information (capability information) of the RX. The TX receiving the signal of the ID packet and the configuration packet returns an acknowledgement (positive response ACK). Then, the I&C phase ends.

[0134] In the negotiation phase, the value of GP is determined based on the GP value requested by RX or the power supply capability of TX, etc. TX receives a FOD status data packet including a reference quality factor value and a reference resonant frequency value from RX.

[0135] The reference quality factor value is a Q factor that can be measured by the terminals of the power transmitting antenna of the test TX when the RX is placed on the test TX and there is no foreign matter in the vicinity thereof.

[0136] The reference resonance frequency value is a resonance frequency that can be measured by the terminal of the power transmission antenna of the test TX when the RX is placed on the test TX and there is no foreign matter in the vicinity thereof.

[0137] In the Q-factor measurement method, the presence or absence of foreign matter is determined based on a threshold value based on a reference quality factor value and a reference resonance frequency value.

[0138] TX performs foreign object detection processing using the Q factor measurement method in response to a request from RX. In the WPC standard, a method is defined for performing the same processing as in the negotiation phase again in response to a request from RX after a transition to the power transmission phase is performed once. The phase to which the power transmission phase transitions and these processes are performed is called the renegotiation phase.

[0139] In the calibration phase, CAL processing is performed based on the WPC standard. RX notifies TX of a predetermined received power value, and TX performs adjustment for efficiently transmitting power.

[0140] The predetermined received power value is, for example, a received power value in a light load state or a maximum load state (connected load state). The received power value notified to the TX is used for foreign object detection processing using a power loss method.

[0141] In the power transmission phase, TX and RX control the start and continuation of power transmission, or the stop of power transmission due to error processing or full charging, etc. TX and RX perform communication processing for power transmission / reception control.

[0142] For example, using the power transmission antenna 105 and the power receiving antenna 205 for wireless power transmission based on the WPC standard, communication is performed by superimposing a signal on the electromagnetic wave transmitted from the power transmission antenna 105 or the power receiving antenna 205. The range in which communication based on the WPC standard can be performed between TX and RX is the same range as the power transmittable range of TX.

[0143] The following will refer to Figure 5 The function of the TX control unit 101 will be described. Figure 51 is a block diagram illustrating an example of a functional structure of a control unit 101 of a power transmission device 100 (TX). The control unit 101 includes 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 performs communication control for RX based on the WPC standard via the first communication unit 104, or performs communication control for RX via the second communication unit 109.

[0144] The power transmission control unit 302 controls the power transmission to the RX by controlling the power transmission unit 103. The measuring unit 303 measures the waveform attenuation index to be described later. The measuring unit 303 measures the power transmitted to the RX via the power transmission unit 103, and measures the average power transmission per unit time. The measuring unit 303 measures the Q factor of the power transmission antenna 105.

[0145] The setting unit 304 calculates and sets a threshold value for foreign object detection based on the waveform attenuation index measured by the measuring unit 303. The setting unit 304 calculates and sets a threshold value for foreign object detection or a threshold value for misalignment detection 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 measuring unit 303.

[0146] The state detection unit 305 detects the state of TX and RX. For example, the state detection unit 305 acquires a quantity (such as a coupling coefficient) indicating the state of electromagnetic coupling between the power transmitting antenna 105 and the power receiving antenna 205. The state detection unit 305 detects the presence of foreign matter between TX and RX, and detects misalignment between the power transmitting antenna 105 and the power receiving antenna 205.

[0147] More specifically, a state detection process based on a power loss method, a Q factor measurement method, a waveform attenuation method, and an electromagnetic coupling state between the power transmitting antenna 105 and the power receiving antenna 205 can be performed. The state detection unit 305 can use other methods to perform foreign object detection or misalignment detection between the power transmitting antenna 105 and the power receiving antenna 205.

[0148] For example, in a TX having an NFC communication function, the state detection unit 305 performs state detection processing using a counterpart detection function based on the NFC standard. In addition to detecting the presence of foreign matter or detecting 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 state detection unit 305 can detect an increase or decrease in the number of power receiving devices 200 on the TX.

[0149] The setting unit 304 sets a threshold value used as a reference for determining whether a foreign object exists when the TX detection state is detected. The detection of the state is based on, for example, a power loss method, a Q factor measurement method, or a waveform attenuation method, or based on the coupling coefficient between the power transmitting antenna 105 and the power receiving antenna 205.

[0150] The setting unit 304 may use other methods to set the judgment threshold required for the state detection process. The state detection unit 305 may perform foreign object detection processing or misalignment detection processing between the power transmitting antenna 105 and the power receiving antenna 205 based on the threshold set by the setting unit 304 and the measurement result from the measurement unit 303.

[0151] For example, the state detection unit 305 may acquire data such as a waveform attenuation index, transmitted power, a Q factor, and a coupling coefficient between the power transmitting antenna 105 and the power receiving antenna 205 as measurement results from the measurement unit 303 .

[0152] Depend on Figure 5 The processes performed by the illustrated communication control unit 301 , the power transmission control unit 302 , the measurement unit 303 , the setting unit 304 , and the state detection unit 305 can be realized using a program executed by a CPU or the like of the control unit 101 .

[0153] These processes are performed in parallel by synchronizing independent programs through event processing, etc. Two or more of these processes may be incorporated into a process using a single program.

[0154] The following will refer to Figure 6 The function of the RX control unit 201 will be described. Figure 6 201 includes a communication control unit 701 , a power reception control unit 702 , a measurement unit 703 , a setting unit 704 , a state detection unit 705 , and a determination unit 706 .

[0155] The communication control unit 701 performs communication control for TX based on the WPC standard via the first communication unit 204 , or performs communication control for TX via the second communication unit 212 .

[0156] The power reception control unit 702 controls reception of power from the TX by controlling the power reception unit 203. The measurement unit 703 measures power received from the TX via the power reception unit 203, and measures average reception power per unit time.

[0157] The setting unit 704 sets the received power measured by the measuring unit 703 or the GP value based on the negotiation with TX as the maximum power consumption value. The maximum power consumption value is the maximum value of the power that can be permitted by RX, and is a variable power value that can be increased or decreased by RX. The power transmission output change request sent from RX to TX is used to make TX increase the transmission power value, transmission voltage or transmission current.

[0158] As a power transmission output change request, the WPC standard includes a control error packet (hereinafter abbreviated as CE) used by RX to request TX to increase or decrease the power receiving voltage (or power receiving current or power receiving power value).

[0159] The control error value (hereinafter abbreviated as CEV) is stored in the CE. CEV is a criterion (difference information) for indicating the difference between the actual operating point of the RX and the operating point (target operating point) as a target, and is represented as an 8-bit signed integer. Here, the operating point indicates a combination of the frequency, duty cycle, and amplitude of the voltage applied to the power transmission unit.

[0160] When CEV is a positive value, it means that the actual operating point is lower than the target operating point, and RX requests TX to increase the strength of the power signal. Specifically, RX requests TX to increase the power transmission voltage or the power transmission current. On the other hand, when CEV is a negative value, it means that the actual operating point is higher than the target operating point, and RX requests TX to reduce the strength of the power signal.

[0161] Specifically, RX requests TX to reduce the power transmission voltage or power transmission current. When CEV is zero, it means that RX requests TX to maintain the current operating point.

[0162] TX quickly performs power transmission control based on the sign and integer stored in CE. The difference information included in the power transmission output change request in this embodiment will be specifically described. When the CEV value of an integer with a + (positive) sign is stored in CE, TX performs control for quickly increasing the power transmission voltage.

[0163] The CEV in this case is referred to as CEV(+). When the CEV value of an integer having a -(negative) sign is stored in CE, TX performs control for rapidly reducing the power transmission voltage.

[0164] The CEV in this case is referred to as CEV(-). When "0" is stored in CE as the CEV value, TX performs control for maintaining the current power transmission voltage. The CEV in this case is referred to as CEV(0).

[0165] The state detection unit 705 detects the state of TX and RX. For example, the state detection unit 705 detects the presence of foreign matter between TX and RX, and detects misalignment between the power transmitting antenna 105 and the power receiving antenna 205.

[0166] More specifically, a state detection process based on a power loss method, a Q factor measurement method, a waveform attenuation method, and an electromagnetic coupling state (e.g., a coupling coefficient) between the power transmitting antenna 105 and the power receiving antenna 205 may be performed. The state detection unit 705 may use other methods to perform foreign object detection or misalignment detection between the power transmitting antenna 105 and the power receiving antenna 205.

[0167] For example, in an RX with NFC communication function, the state detection unit 705 performs state detection processing using a counterpart detection function based on the NFC standard. In addition to detecting the presence of foreign matter or the electromagnetic coupling state between the power transmitting antenna and the power receiving antenna, the state detection unit 705 can also detect state changes under the RX.

[0168] For example, the state detection unit 705 can detect an increase or decrease in the number of coils of the TX located below the RX, etc. The judgment unit 706 judges the value included in the power transmission output change request used by the RX to request the TX to increase or decrease the power receiving voltage (or power receiving current or power receiving power). Figure 7 The details of the power transmission output change request will be described below.

[0169] Depend on Figure 6 Processing performed by the illustrated communication control unit 701 , power reception control unit 702 , measurement unit 703 , setting unit 704 , state detection unit 705 , and determination unit 706 can be realized using a program executed by a CPU or the like of the control unit 201 .

[0170] These processes are performed in parallel by synchronizing independent programs through event processing, etc. Two or more of these processes may be incorporated into a process using a single program.

[0171] The WPC standard defines the selection phase, ping phase, I&C phase, negotiation phase, calibration phase, and power transmission phase. Figure 7 An example of the operation of TX and RX in these stages is shown below.

[0172] Figure 7 1 is a sequence diagram illustrating wireless power transmission based on the WPC standard, in which the operation of TX is illustrated in the left part and the operation of RX is illustrated in the right part. F501 to F517 represent symbols and numbers for distinguishing operations in steps in time series.

[0173] In F501, TX repeatedly intermittently sends a simulated ping to detect an object existing in the power transmittable range. TX performs the processing defined in the selection phase and the ping phase, and waits until RX is placed on it.

[0174] In F502, a user of RX (eg, a smart phone) brings RX close to TX for charging. For example, the user brings RX close to TX by placing RX on TX.

[0175] After sending the analog ping in F503, TX detects the presence of an object in the power transmission range in F504. TX sends a digital ping in F505. When RX receives the digital ping, it can be determined in F506 that TX has detected RX.

[0176] When a predetermined response to the digital ping is returned from the RX, the TX determines that the detected object is the RX and the RX is placed on the charging stand 300 .

[0177] When it is detected that RX is placed on TX, the exchange of identification information and capability information is performed in F507. TX obtains identification information and capability information from RX through communication in the I&C phase. The identification information of RX may include a manufacturer code and a basic device ID.

[0178] The capability information of the RX may include an information element capable of identifying a corresponding version of the WPC standard, or information indicating whether the RX has a maximum power value, which is a value for identifying a maximum power that can be supplied to the load, and a negotiation function.

[0179] TX may obtain the identification information and capability information of RX using a method other than the communication in the I&C phase in the WPC standard. The identification information may be any other identification information for identifying the entity of RX, such as a wireless power ID, etc. Information other than the above may be included in the capability information.

[0180] Subsequently, in F508, TX determines the GP value for RX through the communication in the negotiation phase. Here, in F508, processing for determining the GP value other than the communication in the negotiation phase in the WPC standard may be performed.

[0181] When TX acquires information indicating that RX should not negotiate, for example, in F507, communication in the negotiation phase is not performed, and the GP value may be set to a small value specified in the WPC standard. In this embodiment, GP=5 (Watts) is set.

[0182] After determining the GP value, TX performs calibration based on the GP value. In the CAL process, first, in F509, RX sends information including the received power in the light load state (hereinafter referred to as "first reference received power information") to TX. For example, the light load state is a load cut-off state, or a load state in which the transmitted power value is equal to or less than the first threshold.

[0183] The first reference power receiving information in this embodiment is defined as the power receiving information of RX when the transmission power of TX is 250 mW. The first reference power receiving information is information of the power receiving packet (mode 1) defined in the WPC standard, and other messages may be used.

[0184] TX determines whether to receive the first reference power receiving information based on the power transmission state of TX. TX sends an affirmative response (ACK) to RX when it is about to receive the first reference power receiving information, and sends a negative response (NAK) to RX when it is not about to receive the first reference power receiving information. Figure 7 In the illustrated example, in F510 , TX sends ACK to RX.

[0185] Then, RX transmits information including the received power in the connected load state (hereinafter referred to as "second reference received power information") to TX. For example, the connected load state is a maximum load state or a load state where the transmitted power value is equal to or greater than the second threshold.

[0186] In this embodiment, since the GP value is 5, the second reference power receiving information is defined as the power receiving information of RX when the power transmission power of TX is 5 watts. Here, the second reference power receiving information is information of the power receiving packet (mode2) defined in the WPC standard, and other messages may be used.

[0187] In F511, RX transmits a power transmission output change request including a positive value (CE storing CEV (+)) to TX to increase the transmission power from TX to 5 watts. In F512, TX increases the transmission power in response to the power transmission output change request. Then, the transmission of the power transmission output change request in RX in F513 and the change of the transmission power output in TX in F514 (increase of the transmission power) are repeated.

[0188] In F515, when it is determined that the transmission power output has reached 5 watts as the predetermined power, RX transmits information including the reception power value in the connected load state as the second reference reception power information to TX. In F516, TX transmits ACK in response to the second reference reception power information received from RX, and ends the CAL process.

[0189] TX, which determines that the charging process can be started, starts the process of sending power to RX in F517, and charging of RX starts. In this way, the power transmission phase starts. In the power transmission phase in which TX sends power to RX, RX and TX appropriately perform transmission of a power transmission output change request and change of the power transmission output.

[0190] Figure 8 This is a diagram illustrating the principle of detecting foreign matter using the waveform attenuation method. Figure 8 In the illustrated example, foreign matter is detected using a power transmission waveform associated with power transmission from the power transmission device 100 (TX) to the power reception device 200 (RX). Figure 8 , the horizontal axis represents time, and the vertical axis represents a voltage value or a current value.

[0191] For example, Figure 8 The waveform 600 shown in the example shows the change in the voltage value of the high frequency voltage applied to the power transmission antenna 105 of TX over time. TX, which is transmitting power to RX via the power transmission antenna 105, at time T 0 Stop power transmission.

[0192] At time T 0 At , the supply of the transmitted power from the power supply unit 102 is stopped. The frequency f of the power transmission waveform is, for example, a fixed frequency between 85 kHz and 205 kHz used in the WPC standard.

[0193] Point 601 on waveform 600 is a point on the envelope of the high frequency voltage and is related to time T 1 The voltage value at A 1 Correspondingly, point 601 (T 1 ,A 1 ) indicates time T 1 The voltage value at is A 1 .

[0194] Point 602 on waveform 600 is a point on the envelope of the high frequency voltage and is related to time T 2 The voltage value at A 2 Correspondingly, point 602 (T 2 ,A 2 ) indicates time T 2 The voltage value at is A 2 .

[0195] Based on time T 0 The quality factor (Q factor) of the power transmitting antenna 105 is calculated based on the time change of the voltage value thereafter. For example, TX uses Expression 1 to calculate the Q factor based on the timing, voltage value, and frequency f of the high frequency voltage at points 601 and 602 on the envelope of the high frequency voltage.

[0196] Q=π·f·(T 2 -T 1 ) / ln(A 1 / A 2 )…(Expression 1)

[0197] In Expression 1, ln represents a natural logarithm function.

[0198] The value of the Q factor decreases when foreign matter exists in the vicinity of TX and RX, and the reason is that energy loss occurs due to the foreign matter. Therefore, focusing on the attenuation slope of the voltage value, when foreign matter exists, the slope of the straight line connecting point 601 and point 602 becomes larger than when foreign matter does not exist.

[0199] When energy loss due to foreign matter occurs, the attenuation rate of the amplitude of waveform 600 increases. For example, in the waveform attenuation method, it can be determined whether foreign matter exists based on the attenuation state of the voltage value between point 601 and point 602.

[0200] When actually judging whether a foreign object is present, the judgment can be made by comparing certain numerical values ​​indicating the attenuation state. For example, in the judgment using the Q factor, when the value of the Q factor is less than the reference value, this means that the waveform attenuation rate (the degree of reduction in the amplitude of the waveform per unit time) has increased.

[0201] For example, you can use (A 1 -A 2 ) / (T 2 -T 1 ) is used to make this determination. 1 and T 2 ) is fixed, the voltage difference (A 1 -A 2 ) or voltage ratio (A 1 / A 2 ) to determine whether there is a foreign object.

[0202] Alternatively, at the voltage value A immediately after the power transmission has stopped 1 When the voltage is constant, the voltage value A after a predetermined time can be used. 2 Alternatively, the voltage value A can be used to determine whether there is a foreign object. 1 Reaching the predetermined voltage value A 2 The time elapsed until (T 2 -T 1 ) to determine whether there is a foreign object.

[0203] In the waveform decay method, the presence or absence of foreign matter can be determined based on the decay state of the waveform in the power transmission stop period. In the present embodiment, indices such as Q factors indicating the decay state are collectively referred to as "waveform decay indices."

[0204] Figure 8 The vertical axis in FIG. 1 is described as the axis of the voltage value of the high frequency voltage applied to the TX power transmission antenna 105, but Figure 8 The vertical axis in can be set to the current value flowing in the power transmission antenna 105. Similar to the voltage value, the attenuation state of the current value in the power transmission stop period changes depending on whether there is a foreign object. When there is a foreign object, the waveform attenuation rate is higher than when there is no foreign object.

[0205] Therefore, foreign matter can be detected by applying the same method as described above to the time change of the current value flowing in the power transmitting antenna 105. That is, the Q factor calculated from the current waveform, the attenuation slope of the current value, the difference between the current values, the ratio of the current values, the absolute value of the current value, or the time until the current value reaches a predetermined value, etc., can be used as a waveform attenuation index to determine whether a foreign matter is present and detect the foreign matter.

[0206] A method based on both the attenuation state of the voltage value and the attenuation state of the current value may be used. In this method, the presence or absence of foreign matter may be determined using an evaluation value calculated based on a waveform attenuation index of the voltage value and a waveform attenuation index of the current value.

[0207] The present disclosure is not limited to the example of measuring the waveform attenuation index in the period when TX temporarily stops power transmission. The waveform attenuation index may be measured in the period when TX temporarily reduces the power supplied from the power supply unit 102 from a predetermined power level to a lower power level.

[0208] The following will refer to Figure 8 A specific example of a method for detecting a foreign object based on a power transmission waveform (a voltage waveform applied to a power transmission antenna or a current waveform flowing in a power transmission antenna) using a waveform attenuation method will be described.

[0209] In the transient response period immediately after power transmission from TX has started, the power transmission waveform is unstable. Therefore, in the transient response period, control is performed so that RX does not communicate with TX based on load modulation or amplitude modulation. Control is performed so that TX does not communicate with RX based on frequency shift modulation.

[0210] TX is performing foreign body detection at a timing (time T 0 ) temporarily stops power transmission to RX. During the foreign object detection period in which power transmission is temporarily stopped, the amplitude of the power transmission waveform decays. TX calculates the waveform decay rate of the power transmission waveform at this time.

[0211] When the calculated waveform attenuation rate is greater than a predetermined threshold, TX determines that a foreign object is present. After the predetermined foreign object detection time period has expired, when TX determines that no foreign object is detected, TX restarts power transmission to RX. After power transmission has been restarted, TX repeats waiting in the transition response time period, determination of foreign object detection timing, stopping of power transmission, and foreign object detection processing.

[0212] When elements such as the power receiving unit 203 , the charging unit 206 , and the battery 207 are connected to the power receiving antenna 205 and the resonance capacitor 211 of the power receiving device 200 at the time of measurement of the waveform attenuation index, the waveform attenuation index is affected by the influence of these elements on the load.

[0213] That is, the value of the waveform attenuation index changes according to the states of the power receiving unit 203, the charging unit 206, and the battery 207. As a result, for example, even in the case where the value of the waveform attenuation index is large, it is difficult to distinguish the cause between the influence of foreign matter and the state change of the power receiving unit 203, the charging unit 206, and the battery 207.

[0214] Therefore, when measuring the waveform attenuation index and detecting foreign matter, the RX control unit 201 turns off the first switch unit 209. This can suppress the influence of the battery 207.

[0215] Alternatively, the control unit 201 turns on and short-circuits the second switch unit 210 so that current flows in a closed loop circuit formed by the power receiving antenna 205, the resonance capacitor 211, and the second switch unit 210. Therefore, the influence of the power receiving unit 203, the charging unit 206, and the battery 207 can be suppressed.

[0216] As described above, by performing foreign object detection in a state where the first switch unit 209 is turned off or in a state where the second switch unit 210 is turned on and short-circuited (connected), foreign objects can be detected with higher accuracy.

[0217] Alternatively, by performing both the cut-off of the first switch unit 209 and the short-circuit (connection) of the second switch unit 210, foreign matter can be detected with much higher accuracy. The same beneficial effect is obtained by detecting foreign matter in a light load state instead of the state where the first switch unit 209 is cut off.

[0218] When elements such as the power transmission unit 103 , the first communication unit 104 , and the power supply unit 102 are connected to the power transmission antenna 105 and the resonance capacitor 107 of the power transmission device 100 at the time of measurement of the waveform attenuation index, the waveform attenuation rate is affected by these elements.

[0219] That is, the value of the waveform attenuation index changes according to the states of the power transmission unit 103, the first communication unit 104, and the power supply unit 102. As a result, for example, in the case where the value of the waveform attenuation index is large, it is difficult to distinguish the cause between the influence of foreign matter and the state change of the power transmission unit 103, the first communication unit 104, and the power supply unit 102.

[0220] Therefore, when measuring the waveform attenuation index, the TX control unit 101 turns on the switch unit 108 so that current flows in the closed loop circuit formed by the power transmission antenna 105 , the resonance capacitor 107 , and the switch unit 108 .

[0221] Therefore, the influence of the power transmission unit 103, the first communication unit 104, and the power supply unit 102 can be suppressed. Alternatively, a switch can be provided between the closed loop circuit formed by the power transmission antenna 105, the resonance capacitor 107, and the switch unit 108 and the power transmission unit 103. TX controls the switch to cut off the closed loop circuit from the power transmission unit to suppress the influence during the measurement of the waveform attenuation index and the detection of foreign matter.

[0222] As described above, foreign matter can be detected with higher accuracy by performing detection of foreign matter in the short-circuited (connected) state in which the switch unit 108 is turned on or in the disconnected state in which the closed-loop circuit is disconnected by the switch and the power transmission unit 103 is disconnected. Alternatively, foreign matter can be detected with much higher accuracy by performing both short-circuiting of the switch unit 108 and disconnection of the switch.

[0223] The following will refer to Fig. 9 The following describes a method for setting a threshold value for a waveform attenuation index when using the waveform attenuation method to detect a state or a foreign object. Fig. 9 In FIG. 1 , the horizontal axis represents the transmitted electric power of the power transmission device 100 , and the vertical axis represents the waveform attenuation index (waveform attenuation rate) of the voltage waveform or the current waveform.

[0224] On the graph indicated by the linear segment 1102, point 1100 corresponds to the transmitted power value Pt1 and the waveform attenuation index δ1, and point 1101 corresponds to the transmitted power value Pt2 and the waveform attenuation index δ2. On the graph, point 1103 corresponds to the transmitted power value Pt3 and the waveform attenuation index δ3.

[0225] First, RX performs control so that RX is in a light load state when power is transmitted from TX. In the light load state, power is not supplied to the load of RX, or only power less than a threshold is supplied to the load of RX.

[0226] In this state, the transmission power value of TX is defined as Pt1. Then, TX stops power transmission or reduces the transmission power in the light load state, and measures the waveform attenuation index δ1. At this time, TX recognizes the transmission power value Pt1 and stores CP 1100, which is a calibration point related to the transmission power value Pt1 and the waveform attenuation index δ1, in the memory.

[0227] Then, RX controls a connected load state. The connected load state is a state in which the load of RX is supplied with maximum power or with power equal to or greater than a predetermined threshold value when power is transmitted from TX.

[0228] The transmission power value of TX in this state is defined as Pt2. Then, TX stops power transmission or reduces the transmission power in the load connection state, and measures the waveform attenuation index δ2. At this time, TX stores CP 1101, which correlates the transmission power value Pt2 with the waveform attenuation index δ2, in the memory.

[0229] Then, TX generates line segment 1102 by linear interpolation between CP 1100 and CP 1101. Line segment 1102 indicates the relationship between the transmitted power and the waveform attenuation index (waveform attenuation rate) of the transmitted power waveform in the first detection state where no foreign matter exists near TX and RX.

[0230] Therefore, TX can estimate the waveform attenuation index of the power transmission waveform for each power transmission value in the first detection state based on the line segment 1102. For example, from the point 1103 corresponding to Pt3 on the line segment 1102, the waveform attenuation index of the power transmission value Pt3 is estimated to be δ3.

[0231] TX can calculate a threshold value for each transmission power value for judging whether a foreign object exists based on the estimation result. For example, a waveform attenuation index that is greater than a predetermined value (a value corresponding to the measurement error) relative to the estimation result of the waveform attenuation index in the first detection state at a certain transmission power value can be set as a threshold value for judging whether a foreign object exists.

[0232] In the following description, the CAL process performed by the power transmission device 100 and the power reception device 200 so that the power transmission device 100 obtains a combination of the transmission power value and the waveform attenuation index is referred to as "CAL process using the waveform attenuation method". RX can perform the control of the light load state and the control of the connected load state after the notification of TX. One of the two types of control can be performed first.

[0233] The process of calculating the threshold value for determining the presence or absence of a foreign object for each load (or each transmitted power value) described in this embodiment can be performed in the calibration phase. As described above, TX acquires data required for detecting a foreign object using the power loss method in the calibration phase.

[0234] At this time, TX acquires data related to power consumption when the load state of RX is a light load state and when the load state of RX is a connected load state. Thereafter, in the calibration phase, Fig. 9 The measurements of CP 1100 and CP 1101 in the RX can be performed together with the measurements of the power loss when the RX is in a light load state and when the RX is in a connected load state.

[0235] For example, upon receiving a signal including the first reference power information from RX, TX performs measurement of CP 1100 in addition to the predetermined processing to be performed in the calibration phase. The first reference power information is information in a power data packet (mode1) defined in the WPC standard, and other messages may be used.

[0236] When receiving a signal including the second reference received power information from RX, TX performs measurement of CP 1101 in addition to the predetermined processing to be performed in the calibration phase. The second reference received power information is information in a received power data packet (mode2) defined in the WPC standard, and other messages may be used.

[0237] Since it is not necessary to separately provide time periods for measuring the CP 1100 and the CP 1101 , the CP 1100 and the CP 1101 can be measured in a shorter time.

[0238] When the Q factor calculated using, for example, Expression 1 is used as a waveform attenuation index, a method for setting a threshold value based on a reference quality factor value is used.

[0239] The reference quality factor value is added to the FOD status data packet and sent by the RX to the TX. The reference quality factor value is the Q factor that can be measured by the terminals of the power transmission antenna of the test TX when the RX is placed on the test TX and there is no foreign matter in its vicinity.

[0240] The reference quality factor value is physically synonymous with the Q factor calculated using Expression 1, and thus the threshold value can be set using the reference quality factor value. 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 can be set as the threshold value for determining whether a foreign object is present.

[0241] TX can perform the waveform attenuation method in a state where there is no foreign matter (a state where there is no state abnormality), and set the measurement result of the waveform attenuation index as a threshold. The timing of measuring the waveform attenuation index in the state where there is no foreign matter in advance will be described below.

[0242] When foreign matter is detected using the Q factor measurement method in the negotiation phase in the WPC standard and it is determined that no foreign matter exists, the phase enters the calibration phase and the power transmission phase.

[0243] That is, when the stage enters the stage after the negotiation stage, it means that as a result of the foreign body detection using the Q factor measurement method, it is determined that there is no foreign body. In one of the negotiation stage, calibration stage, and power transmission stage, it is highly likely that the waveform attenuation index in the state where there is no foreign body can be measured.

[0244] Therefore, the timing of measuring the waveform attenuation index in a state where no foreign matter exists may be one of the negotiation phase, the calibration phase, and the power transmission phase.

[0245] For example, it is assumed that the waveform attenuation index in the power transmission stage is measured. The timing of measuring the waveform attenuation index in a state where no foreign matter exists is set as the first step of the power transmission stage.

[0246] This is because, from the time point when it is determined that there is no foreign matter using the Q factor measurement method, as time passes, the probability that there is a foreign matter near TX and RX becomes greater. This timing is specified by RX or TX, and TX measures the waveform attenuation index at this time and sets the value of the waveform attenuation index as a threshold. The value obtained by adding a predetermined value (a value corresponding to the measurement error) to the waveform attenuation index can be set as the threshold for determining whether there is a foreign matter.

[0247] The number of judgment thresholds set using the above method is not limited to one. Multiple thresholds can be set step by step. For example, the first threshold is set as a threshold for judging whether there is a state abnormality, and the second threshold is set as a threshold for judging whether the possibility of a state abnormality is high. The third threshold is set as a threshold for judging whether the possibility of a state abnormality is low, and the fourth threshold is set as a threshold for judging whether there is no state abnormality.

[0248] As a method of measuring the coupling state between the power transmitting antenna and the power receiving antenna, a first measurement method will be described below. In wireless power transmission, the power transmitting antenna 105 and the power receiving antenna 205 are electromagnetically coupled, and power transmission is performed.

[0249] By causing AC current to flow in the power transmitting antenna 105 and changing the magnetic flux penetrating the power receiving antenna 205, a voltage is induced in the power receiving antenna 205. The coupling coefficient (hereinafter referred to as k) which is an index indicating the coupling state between the power transmitting antenna and the power receiving antenna is set to "k = 1" when the entire magnetic flux (100%) generated in the power transmitting antenna passes through the power receiving antenna, for example.

[0250] When 70% of the magnetic flux generated in the power transmitting antenna passes through the power receiving antenna, "k=0.7" is set. In this case, the remaining magnetic flux (30%) generated in the power transmitting antenna is flux leakage (magnetic flux leakage).

[0251] This is the magnetic flux generated in the power transmitting antenna that does not pass through the power receiving antenna. Therefore, when the coupling state between the power transmitting antenna and the power receiving antenna is good and the k value is large, the transmission efficiency of the power sent from TX to RX is high. On the other hand, when the coupling state is not good and the k value is small, the transmission efficiency of the power sent from TX to RX is low.

[0252] The reasons for reducing the value of the coupling coefficient include the presence of foreign matter (such as a metal piece) between the power transmitting antenna and the power receiving antenna and misalignment between the power transmitting antenna and the power receiving antenna. When there is foreign matter between the power transmitting antenna and the power receiving antenna, there is a possibility that the foreign matter will be heated.

[0253] When misalignment occurs between the power transmitting antenna and the power receiving antenna, flux leakage (magnetic flux leakage) increases, and there is a possibility that large noise will be generated nearby. When the k value is small, appropriate control is required to achieve wireless power transmission with higher safety and higher quality. In this embodiment, processing is performed to detect the coupling state (including the coupling coefficient) between the power transmitting antenna and the power receiving antenna to improve the detection accuracy of foreign matter or the detection accuracy of misalignment.

[0254] The following will refer to Fig.10 (A) and (B) of FIG. 1 illustrate a method for measuring the coupling state between the power transmitting antenna and the power receiving antenna. Fig.10 (A) is an equivalent circuit diagram illustrating the first measurement method. Definitions of physical quantities associated with the power transmission antenna (power transmission coil) on the primary side (TX) are as follows.

[0255] -r1: coil resistance of the power transmission coil

[0256] -L1: Self-inductance of the power transmission coil

[0257] -V1: The power transmission voltage (input voltage) measured by TX and applied to the power transmission coil

[0258] The physical quantities associated with the power receiving antenna (power receiving coil) on the secondary side (RX) are defined as follows.

[0259] -r2: coil resistance of the power receiving coil

[0260] -L2: Self-inductance of the receiving coil

[0261] -V2: The power receiving voltage (output voltage) measured by RX and applied to the power receiving coil

[0262] The coupling coefficient k between the power transmitting coil and the power receiving coil can be calculated using Expression 2.

[0263]

[0264] When TX calculates the coupling coefficient k, RX notifies TX of the measured power receiving voltage V2 and the value of the self-inductance L2 of the power receiving coil pre-stored in RX. TX calculates the value k using the measured power transmission voltage V1, the value of the self-inductance L1 of the power transmission coil pre-stored in itself, and the power reception voltage V2 and the value of the self-inductance L2 received from RX.

[0265] Alternatively, RX notifies TX of a constant and the power reception voltage V2 calculated using both or one of L1 and L2, and TX may calculate the k value using the constant and the power reception voltage V2 received from RX and the power transmission voltage V1 measured by TX.

[0266] On the other hand, when RX calculates the coupling coefficient k, TX notifies RX of the measured power transmission voltage V1 and the value of the self-inductance L1 of the power transmission coil stored in advance. RX calculates the k value using the measured power reception voltage V2, the value of the self-inductance L2 of the power reception coil stored in advance in itself, and the values ​​of the power transmission voltage V1 and self-inductance L1 received from TX.

[0267] Alternatively, TX notifies RX of a constant and the power transmission voltage V1 calculated using both or one of L1 and L2, and RX may calculate the k value using the constant and the power transmission voltage V1 received from TX and the power reception voltage V2 measured by RX.

[0268] The power transmission voltage V1 is acquired by causing the TX to actually measure the voltage applied to the power transmission coil or by causing the TX to calculate the power transmission voltage from the setting value of the power transmission power. Alternatively, the power transmission voltage V1 may be used as the setting value of the power transmission voltage at the time of power transmission.

[0269] The power transmission voltage V1 applied to the power transmission coil can be calculated using a power transmission voltage (referred to as V3 ) applied to a circuit (eg, inverter) included in the power transmission unit 103 of the TX and a voltage applied across the resonance capacitor 107 .

[0270] In this case, TX may calculate the power transmission voltage V3 according to the set value of the power transmission power. Alternatively, TX may actually measure the power transmission voltage V3 and the voltage applied to both ends of the resonance capacitor 107 and calculate the power transmission voltage V1 using the measured voltages.

[0271] When TX or RX performs the first measurement, RX can control so that the third switch unit 213 is turned off and the terminal of the power receiving antenna 205 is in an open state. Fig.10 As illustrated in (A), both ends of the power receiving coil can be switched to an open state. Since the first measurement is not affected by the resonance capacitor 211, the power receiving unit 203, the charging unit 206, and the battery 207, the coupling coefficient k can be measured with higher accuracy.

[0272] The power receiving voltage V2 applied to the power receiving coil can be calculated using the power receiving voltage (referred to as V4) applied to a circuit (e.g., a rectifier) ​​included in the power receiving unit 203 of the RX and the voltage applied across the resonant capacitor 211. In this case, the RX can actually measure the power receiving voltage V4 and the voltage applied across the resonant capacitor 211, and calculate the power receiving voltage V2 using the measured voltages.

[0273] Alternatively, when TX or RX performs the first measurement, RX may be controlled so that RX is in a light load state or a connected load state. By making the load state of RX constant, the coupling coefficient k may be measured with higher accuracy.

[0274] A plurality of quantities other than the coupling coefficient can be used as an index indicating the electromagnetic coupling state between the power transmitting antenna and the power receiving antenna, and in the present embodiment, these quantities are collectively referred to as "coupling state indexes". All coupling state indexes have values ​​corresponding to the electromagnetic coupling state between the power transmitting antenna and the power receiving antenna. The details of the present embodiment can be similarly applied to the case where other coupling state indexes other than the coupling coefficient are used.

[0275] For example, the power transmission voltages V3 and V4 may be used to perform processing for calculating the coupling state between the power transmission antenna and the power receiving antenna. Alternatively, the coupling state between the power transmission antenna and the power receiving antenna may be calculated using the output voltage (referred to as V5) of a circuit (e.g., a rectifier) ​​included in the power receiving unit 203 of the RX.

[0276] The output voltage V5 is the voltage applied to the load (charging unit and battery). TX can notify RX of the transmission voltage V3, and RX can calculate the coupling state index. At this time, TX notifies RX of the constant calculated using the electrical characteristics of the power transmission antenna (e.g., L1), and RX can use the constant to calculate the coupling state index.

[0277] Alternatively, RX notifies TX of the power receiving voltage V4 or the output voltage V5, and TX calculates the value of the coupling state index. At this time, RX can notify TX of a constant calculated using the electrical characteristics of the power receiving antenna (e.g., L2), and TX can calculate the coupling state index using the constant.

[0278] TX and RX transmit and receive information such as voltage values ​​V1 to V5, values ​​of self-inductances L1 and L2, or constants indicating electrical characteristics of a power transmitting antenna or a power receiving antenna relative to each other. The timing of measuring voltage values ​​and the timing of transmitting and receiving various types of information will be described below.

[0279] The measurement of the voltage value is performed, for example, in the ping phase. In the ping phase, TX sends a digital ping to RX. Therefore, one of the voltage values ​​V1, V2, V3, V4, and V5 generated when the digital ping is sent can be used. In the ping phase, TX and RX measure one of the voltage values ​​V1 to V5 and store the measured value in the memory 106 or the memory 208.

[0280] TX receives a predetermined packet including information of one voltage value among the voltage values ​​V2, V4, and V5 notified from RX, and stores the information in the memory 106. The information included in the predetermined packet may include information such as the value of the received power or self-inductance L2 and constants calculated using the electrical characteristics of the power receiving antenna in addition to the received power voltage of RX.

[0281] The signal strength data packet may be used as a predetermined packet to notify the TX of the information of the RX. Alternatively, the predetermined packet may be an identification data packet or an extended identification data packet in the I&C phase.

[0282] Alternatively, the predetermined packet may be a configuration data packet.Alternatively, the predetermined packet may be a packet in a calibration phase or a power transfer phase.

[0283] That is, the predetermined packet may be a received electric power data packet (mode1), a received electric power data packet (mode2), or a received electric power data packet (mode0).

[0284] The present embodiment is not limited to the example of using the voltage value generated when the TX sends a digital ping. In the selection stage, one of the voltage values ​​V1 to V5 generated when the TX sends an analog ping may be used.

[0285] When the RX performs the first measurement method, control can be performed so that the third switch unit 213 between the resonant capacitor 211 and the power receiving unit 203 is disconnected, and the terminal of the circuit composed of the power receiving antenna 205 and the resonant capacitor 211 is in an open state. Therefore, since the execution of the first measurement method is not affected by the power receiving unit 203, the charging unit 206, and the battery 207, the coupling state index can be measured with higher accuracy.

[0286] As another example of a method of measuring the coupling state between the power transmitting antenna and the power receiving antenna, a second measurement method will be described below. Fig.10(B) is an equivalent circuit diagram illustrating the second measurement method. Here, r1, r2, L1 and L2 are Fig.10 The physical quantities associated with the power transmission antenna (coil) on the primary side (TX) are defined as follows.

[0287] -V6: Input voltage of the power transmitting antenna when the power receiving antenna is in a short-circuit state

[0288] -V7: Input voltage of the power transmitting antenna when the power receiving antenna is in the open state

[0289] -I1: Current flowing in the power transmitting antenna when the power receiving antenna is in a short-circuit state

[0290] -I2: Current flowing in the power transmitting antenna when the power receiving antenna is in the open state

[0291] The coupling coefficient k can be calculated using Expression 3.

[0292]

[0293] In Expression 3, Lsc represents the inductance of the power transmission coil when both ends of the power receiving coil are short-circuited. For example, the control unit 201 switches the third switch unit 213 and the second switch unit 210 to the ON state (short-circuit state). The value of Lsc can be obtained by measuring the inductance value of the power transmission coil in this state. The inductance value of the power transmission coil can be calculated based on the input voltage V6 and current I1 of the power transmission coil.

[0294] In Expression 3, Lopen represents the inductance of the power transmission coil when both ends of the power reception coil are open. For example, the control unit 201 switches the third switch unit 213 to the OFF state (open state).

[0295] The value of Lopen can be obtained by measuring the inductance of the power transmission coil in this state. The inductance of the power transmission coil can be calculated based on the input voltage V7 and current I2 of the power transmission antenna. In the second measurement method, the coupling state index (coupling coefficient) can be calculated based on the input voltage and current of the power transmission antenna when both ends of the power receiving antenna are short-circuited and when both ends of the power receiving antenna are open.

[0296] TX can calculate the coupling state index based on the power transmission voltage and current applied to the circuit (eg, inverter) included in the power transmission unit 103. In this case, the input voltages V6 and V7 are the power transmission voltages applied to the circuit (eg, inverter) included in the power transmission unit 103.

[0297] The input voltages V6 and V7 may be voltages applied to two terminals of a series resonant circuit formed by a power transmission antenna and a resonant capacitor. Alternatively, the power transmission voltage applied to a circuit (e.g., an inverter) included in the power transmission unit 103 and the voltage applied to both ends of the resonant capacitor 107 may be measured, and the voltage applied to the power transmission antenna may be calculated based on the measured results.

[0298] That is, the coupling state index can be calculated based on the power transmission voltage applied to the circuit (e.g., inverter) included in the power transmission unit 103 and the voltage applied to both ends of the resonance capacitor 107. In this case, the power transmission voltage applied to the circuit (e.g., inverter) included in the power transmission unit 103 can be calculated according to the setting value of the power transmission power using TX.

[0299] exist Fig.10 In (B), the current I1 or I2 is not limited to the current flowing in the power transmitting antenna, but may be the current flowing in the circuit (for example, inverter) included in the power transmitting unit 103. As described above in this example, the open state and the short-circuit state of the power receiving antenna are realized by causing the control unit 201 to control the second switch unit 210 and the third switch unit 213.

[0300] These states can be realized by the power receiving unit 203. Instead of the short circuit state, a light load state can be used.

[0301] In the second measurement method, TX can calculate the coupling state index by measuring the input voltages V6 and V7 and the currents I1 and I2. Therefore, since information such as the voltage value measured by RX or the inductance value of the power receiving antenna is not required, it is not necessary to notify the information from RX to TX.

[0302] Here, when TX measures input voltage V6 and current I1, RX needs to short-circuit the two terminals of the circuit including the power receiving antenna. When TX measures input voltage V7 and current I2, RX needs to open the two terminals of the circuit including the power receiving antenna.

[0303] That is, the RX needs to control the two terminals of the circuit including the power receiving antenna to the SHORT (short circuit) or OPEN (open) state according to the timing at which the TX measures the input voltage and current.

[0304] The timing of the measurement is determined by TX and notified to RX, or determined by RX and notified to TX. The notification is performed by communication based on the WPC standard between the first communication unit 104 of TX and the first communication unit 204 of RX, or communication based on a standard other than the WPC standard between the second communication unit 109 of TX and the second communication unit 212 of RX.

[0305] The measurement of the input voltages V6 and V7 and the currents I1 and I2 is performed, for example, in the ping phase. In the ping phase, the TX sends a digital ping to the RX. Therefore, the values ​​of the input voltages V6 and V7 or the currents I1 and I2 generated when the digital ping is sent can be used.

[0306] In the ping phase, TX acquires the values ​​of V6, V7, I1, and I2, stores the acquired values ​​in the memory 106, and calculates the coupling state index. The present embodiment is not limited to the example of using the voltage value and the current value generated when TX sends a digital ping. For example, the values ​​of V6, V7, I1, and I2 generated when TX sends an analog ping in the selection phase may be used.

[0307] In the present disclosure, as a method of measuring the coupling state between the power transmitting antenna and the power receiving antenna, both the first measurement method and the second measurement method can be applied. A method for setting a state judgment threshold for the coupling state index acquired using the first measurement method or the second measurement method will be described below.

[0308] The judgment of the state is a judgment associated with the detection of a foreign object between the power transmitting antenna and the power receiving antenna, or a judgment associated with the detection of misalignment between the power transmitting antenna and the power receiving antenna, etc. It is possible to judge whether there is a state abnormality using the state judgment threshold by performing the first measurement method or the second measurement method. The first threshold setting method to the fourth threshold setting method will be described below.

[0309] The first threshold setting method is a method of setting a threshold value for a coupling state index for detecting the state between the power transmitting antenna and the power receiving antenna in a state where there is no state abnormality.

[0310] In the detection of the state, for example, judgment results such as "abnormal state exists", "high possibility of abnormal state exists", "low possibility of abnormal state exists", and "abnormal state does not exist" can be obtained. It is assumed that the RX is placed on the test TX and there is no abnormal state between the power transmitting antenna and the power receiving antenna.

[0311] In this case, the value of the coupling state indicator between the test TX including the power transmitting antenna and the RX including the power receiving antenna can be set as a threshold. The value (threshold) of the coupling state indicator measured in advance is stored in the memory of the RX, and the RX notifies the TX of the threshold. The TX uses the threshold to perform judgment processing associated with the detection of the state. The RX can send the threshold added to the FOD status data packet defined in the WPC standard to the TX.

[0312] The second threshold setting method is a method of setting the coupling state index measured by the TX and RX using the first measurement method or the second measurement method in a state where “there is no abnormality between the power transmitting antenna and the power receiving antenna” as a threshold.

[0313] As a method of checking that “there is no abnormality between the power transmitting antenna and the power receiving antenna”, a foreign object detection means using a power loss method or a TX and RX state detection means using a Q factor measurement method can be used.

[0314] When it is determined that there is no abnormal state, it can be checked with high probability that "there is no abnormal state between the power transmitting antenna and the power receiving antenna". That is, the check is performed by methods and means other than the first measurement method or the second measurement method. When it is determined that "there is no abnormal state" (or "there is no foreign object"), the coupling state index is measured using the first measurement method or the second measurement method, and an appropriate threshold is set based on the measurement result.

[0315] For example, in the WPC standard, a foreign object detection process using a Q factor measurement method is performed in a negotiation phase or a renegotiation phase. When it is determined as "no abnormal state" (or "no foreign object") as a result of the foreign object detection process, the coupling state index is measured using the first measurement method or the second measurement method after the negotiation phase or the renegotiation phase.

[0316] A more appropriate threshold value may be set based on the result of the measurement. A foreign object detection process using the power loss method is performed in the power transmission stage. After the foreign object detection process is performed, the coupling state index may be measured using the first measurement method or the second measurement method, and a more appropriate threshold value may be set based on the result of the measurement.

[0317] Alternatively, a Q factor or the like may be used in the selection phase or the ping phase to perform foreign body detection processing. In this case, after the foreign body detection processing phase is performed, the coupling state index may be measured using the first measurement method or the second measurement method, and an appropriate threshold may be set based on the measurement result.

[0318] The following will refer to Fig.11 The third threshold setting method will be described below. Fig.11 FIG. 1 is a diagram illustrating a method of setting a threshold value in state detection using a coupling state indicator. Fig.11 , the horizontal axis represents the transmitted power, and the vertical axis represents the coupling state index.

[0319] On the graph indicated by a linear line segment 1202 , a point 1200 corresponds to the transmitted power value Pt1 and the coupling state index value k1 , and a point 1201 corresponds to the transmitted power value Pt2 and the coupling state index value k2 .

[0320] In the graph, point 1203 corresponds to the transmission power value Pt3 and the coupling state index value k3. In the following description, it is assumed that the coupling state index value is calculated using the first measurement method using the power receiving voltage V4 or the output voltage V5 of the circuit (e.g., rectifier) ​​included in the power receiving unit 203 of RX.

[0321] When the charging unit 206 and the battery 207 are connected as loads to the power receiving unit 203 of RX (see Figure 3 ), the coupling state index value to be calculated varies according to the load state. It is necessary to set a threshold for the coupling state index to determine whether there is a state abnormality according to the load state.

[0322] When power is transmitted from TX, RX first controls so that the load is in a light load state. The light load state is a state in which power is not supplied to the load of RX or only power equal to or less than a threshold is supplied to the load of RX.

[0323] The transmission power value in this state is defined as Pt1. TX and RX measure the input voltage on the TX side and the received voltage on the RX side in this state. TX and RX exchange information on the input voltage and the received voltage, and TX or RX calculates the coupling state index value k1.

[0324] At this time, TX recognizes the transmission power value Pt1 and stores Pt1 and k1-related CP 1200 in the memory. Then, RX performs control so that the load of RX is in a connected load state when power is transmitted from TX.

[0325] In this state, the load of RX is supplied with maximum power or power equal to or greater than a threshold. The transmission power value of TX in this state is defined as Pt2. TX and RX measure the input voltage on the TX side and the receiving voltage on the RX side in this state.

[0326] TX and RX exchange information about the input voltage and the power receiving voltage, and TX or RX calculates the coupling state index value k2. TX stores CP 1201 related to Pt2 and k2 in the memory.

[0327] Subsequently, TX performs linear interpolation between CP 1200 and CP 1201 and generates line segment 1202. Line segment 1202 indicates the relationship between the transmitted power and the coupling state index in a state where there is no state abnormality in the vicinity of TX and RX.

[0328] TX can estimate the coupling state indicator value for each transmission power value in a state where there is no state abnormality in the vicinity of TX and RX using line segment 1202. For example, it is assumed that the transmission power value is Pt3.

[0329] In this case, the coupling state index value k3 can be estimated from the point 1203 corresponding to the transmission power value Pt3 on the line segment 1202. Based on the estimation result, the TX can calculate a threshold value for determining whether or not there is a state abnormality for each transmission power value.

[0330] For example, a coupling state index value obtained by adding a predetermined value (a value corresponding to a measurement error) to an estimation result of a coupling state index value in the absence of state abnormality at a certain transmission power value may be set as the determination threshold.

[0331] The CAL process performed by the power transmitting device 100 and the power receiving device 200 so that the power transmitting device 100 obtains a combination of the transmission power value and the coupling state index value is called "CAL process using coupling state measurement method". After TX is notified of the control, RX can perform control for switching the load to the light load state and control for switching the load to the connected load state. One of the two types of control can be performed first.

[0332] In this embodiment, for example, the operation of calculating the determination threshold value for detecting the state of each load (or each transmitted power value) is performed in the calibration phase. In the calibration phase, TX acquires data required for detecting foreign matter using the power loss method.

[0333] At this time, TX acquires data on power consumption when the load state of RX is a light load state and when the load state of RX is a connected load state. Fig.11 The measurements of CP 1200 and CP 1201 in the RX can be performed together with the measurements of the power consumption when the RX is in a light load state and when the RX is in a connected load state during the calibration phase.

[0334] That is, upon receiving a signal including the first reference received power information from RX, TX performs measurement of CP 1200 in addition to the predetermined processing to be performed in the calibration phase. The first reference received power information is information in a received power data packet (mode1) defined in the WPC standard, and other messages may be used.

[0335] When receiving a signal including the second reference received power information from RX, TX performs measurement of CP 1201 in addition to the predetermined processing to be performed in the calibration phase. The second reference received power information is information in a received power data packet (mode2) defined in the WPC standard, and other messages may be used.

[0336] Since it is not necessary to separately provide time periods for measuring the CP 1200 and the CP 1201 , the CP 1200 and the CP 1201 can be measured in a shorter time.

[0337] The fourth threshold setting method is a method of causing TX or RX to pre-set a threshold for a coupling state indicator having a value within a predetermined range. For example, when the coupling state indicator is a coupling coefficient k, the range of the k value is "0≤k≤1". For example, TX or RX determines that "there is a state abnormality" when the range is "0≤k<0.2", and determines that "there is a high possibility of a state abnormality" when the range is "0.2≤k<0.5".

[0338] TX or RX is judged as "low possibility of state abnormality" when the range is "0.5≤k<0.8", and is judged as "no state abnormality" when the range is "0.8≤k≤1". Data related to the conditions for the k value are pre-stored in the memory, and the judgment process is performed based on these conditions.

[0339] When setting the judgment threshold for detection of the state using the coupling state index, a value obtained by adding a predetermined value (a value corresponding to the measurement error) to the coupling state index value calculated based on the measurement result or the received information can be set as the judgment threshold. The number of thresholds is not limited to one, and a plurality of thresholds can be set step by step as described above.

[0340] The following will describe a state detection process using a Q factor measurement method and a method for measuring the coupling state between a power transmitting antenna and a power receiving antenna. By using the Q factor measurement method together with the first measurement method or the second measurement method, the state can be detected with higher accuracy. Fig.12 The Q factor measurement method will be described in more detail.

[0341] Fig.12 (A) is a schematic circuit diagram illustrating a method of measuring a Q factor using a Q factor measurement method. An AC power source 901 is a power source that outputs AC power generated by a power transmission unit 103 of TX. A power transmission coil 902 corresponds to a power transmission antenna 105, and a capacitor 903 corresponds to a resonant capacitor 107.

[0342] The power transmission 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 transmission unit 103 and which will operate the wireless power transmission system. The voltage value V9 is a voltage value applied to the power transmission coil 902. Here, it is assumed that TX can change the frequency of the voltage value.

[0343] The voltage values ​​V8 and V9 are voltage values ​​measured by the TX when the TX sends an analog ping or a digital ping to the RX. Since the voltage values ​​V8 and V9 are AC voltage values, their root mean square values ​​(RMS) may be used.

[0344] Fig.12 (B) illustrates a characteristic having a peak at 100kHz as an example of the measurement result of V9 / V8 for frequency. The horizontal axis is the frequency axis, and the vertical axis represents the voltage ratio "V9 / V8". V9 / V8 indicates the Q factor associated with the power transmission coil 902, and thus its value changes when an object is placed near the power transmission coil 902.

[0345] The change in Q factor varies between when no object is placed on TX, when RX is placed on TX, when a foreign object (such as a metal piece) is placed on TX, and when RX and a foreign object are placed on TX.

[0346] In the negotiation phase, TX receives a FOD status data packet from RX. The FOD status data packet includes a reference quality factor value and a reference resonant frequency value.

[0347] The reference quality factor value is a Q factor that can be measured using the terminals of the power transmitting antenna of the test TX when the RX is placed on the test TX and there is no foreign matter nearby.

[0348] The reference resonance frequency value is a resonance frequency that can be measured by the terminal of the power transmission antenna of the test TX when the RX is placed on the test TX and no foreign matter exists near it.

[0349] In the Q-factor measurement method, a threshold is set based on a reference quality factor value, and foreign matter is detected by comparing the threshold with the Q-factor calculated from the actually measured V9 / V8.

[0350] Alternatively, the threshold value is set based on the reference resonance frequency value. The detection of foreign matter is performed by comparing the threshold value with the resonance frequency calculated from the actually measured V9 / V8.

[0351] The Q factor measurement method can be used to detect foreign matter mainly when the foreign matter (such as a metal piece) is placed between TX and RX, but the detection accuracy of misalignment between the power transmitting antenna of TX and the power receiving antenna of RX is low.

[0352] On the other hand, the coupling state measurement method can detect misalignment between the power transmitting antenna of TX and the power receiving antenna of RX, and can also detect foreign matter (such as a metal piece) when it is placed between TX and RX. The measurement values ​​using these methods are used to control TX and RX as follows.

[0353] Fig.13is a sequence diagram illustrating an example of basic operation and control between RX and TX according to this embodiment. Figure 7 F501 to F508 are described, and thus description thereof will be omitted, and the sequence will be described from F1301 onwards.

[0354] The message used for the power transmission output change request will be described using CE and CEV in the WPC standard, and other messages used for power transmission output change requests or instructions may be used. Since the GP value in F508 is 5, the reference (target) receiving power information is the receiving power information of RX when the transmission power of TX is 5 watts.

[0355] In F1301, RX sets the maximum power consumption, and then in F1302, TX sends a power transmission output change request including CEV(+) to TX. In F1303, TX changes the transmission power (increases the power) in response to the power transmission output change request from RX.

[0356] In F1304, RX determines whether to send CE including CEV(+) having a value greater than a predetermined threshold to TX for a predetermined time or longer or a predetermined number of times or more. The predetermined time is the time serving as the judgment threshold, and the predetermined number of times is the number of times serving as the judgment threshold. Fig.14 The details of the judgment process will be described.

[0357] In F1305 , RX again transmits a power transmission output change request including CEV(+) to TX. In F1306 , TX changes the transmission power (increases the power) in response to the power transmission output change request from RX.

[0358] In F1307, similarly to F1304, RX performs a judgment process. It is assumed that the same judgment process in F1307 is performed after F1307 and the judgment condition is satisfied. In F1308, RX sends a power transmission stop request to TX.

[0359] For example, end power transfer (EPT) defined in the WPC standard is used as a command for ending power. In F1309, TX stops power transfer to RX in response to EPT from RX.

[0360] The following will refer to Fig.14 The processing on the RX side in the basic operation and control between RX and TX according to the present embodiment will be described. Fig.14 The present invention is a flowchart illustrating a process for transmitting a setting of a maximum power consumption and a power transmission output change request including information on received power in a connected load state, and a process for transmitting a power transmission stop request.

[0361] In S1401, RX sets the maximum power consumption, and then the processing flow enters S1402. In S1402, RX determines whether the setting of the target power has been completed. For example, when it is determined that the maximum power consumption set by RX based on the information related to the power receiving voltage (or power receiving current or power receiving power) at the current time point is not supplied (S1402: No), the processing flow enters S1403.

[0362] When it is determined that the target maximum power consumption is supplied using the CE to the TX (S1402: Yes), the RX determines that the setting of the maximum power consumption is completed, and the processing flow ends.

[0363] In S1403, RX performs initialization processing for transmitting CE. Specifically, processing is performed for starting a transmission timer when CE is transmitted from RX to TX and resetting a transmission counter for recording transmission of CE.

[0364] Then, in S1404, RX sends a power transmission output change request to TX. Specifically, RX sends CE including CEV(+) to TX to increase the transmission power from TX to 5W ( Fig.13 :F1302).

[0365] When the control for the change of the transmitted power starts, there is the largest power difference between RX and TX. Therefore, the value of CEV(+) included in CE at this time is stored in the memory 208 as the first threshold value (referred to as threshold 1) of CEV included in CE continuously transmitted to achieve the target maximum power consumption. TX performs control for increasing the transmitted power in the transmission unit 103 based on the positive specified value of CEV(+) included in CE from RX ( Fig.13 :F1303).

[0366] Then, in S1405, RX determines whether CE including CEV (+) greater than threshold 1 has been transmitted to TX. When it is determined that CE including CEV (+) greater than threshold 1 has been transmitted to TX (S1405: Yes), the processing flow proceeds to S1406. When it is determined that CE including CEV (+) greater than threshold 1 has not been transmitted to TX (S1405: No), the processing flow proceeds to S1402.

[0367] In S1406, RX counts up the transmission counter (+1). In S1407, RX checks the number of times that CE including CEV (+) greater than threshold 1 has been transmitted to TX. When the number of transmissions is equal to or greater than the predetermined number of times (S1407: Yes), the processing flow proceeds to S1409. In this case, RX determines that a system error has occurred.

[0368] This system error is a state in which RX transmits CE including CEV(+) to TX, and the power receiving voltage etc. does not reach the expected value even if the power is continuously transmitted. At this time, an abnormality in both devices is suspected, such as the voltage etc. not increasing due to a malfunction of TX or an erroneous detection of the voltage etc. in RX. On the other hand, when the number of transmissions is less than the predetermined number of times (S1407: No), the processing flow proceeds to S1408.

[0369] In S1408, RX determines whether CE including CEV (+) greater than threshold 1 has been transmitted to TX for a predetermined time or longer. When it is determined that CE has been transmitted to TX for a predetermined time or longer, the process flow proceeds to S1409. When it is determined that CE has not been transmitted to TX for a predetermined time or longer, the process flow proceeds to step S1404.

[0370] In S1409, the first power transmission control is performed. The first power transmission control is performed by causing RX to request TX to stop power transmission. For example, RX sends a power transmission stop request to TX using EPT defined in the WPC standard.

[0371] The EPT is a power transmission stop request packet with a reason including data indicating a reason for requesting TX to stop power transmission. On the other hand, upon receiving the EPT from RX, TX stops the power supply from the power supply unit 102 to the power transmission unit 103, and stops power transmission to RX ( Fig.13 :F1309).

[0372] exist Fig.14 In the illustrated example, when a CE including a CEV (+) larger than a threshold value 1 has been transmitted to TX for a predetermined time or longer or has been transmitted to TX a predetermined number of times or more, the first power transmission control is performed.

[0373] When the number of times CE is sent does not reach the predetermined number of times, the time for sending CE to TX is compared with the threshold time. That is, by checking the clock time of the sending timer started in the initialization process for sending CE, it can be determined whether CE including CEV (+) greater than the threshold 1 has been sent to TX for a time equal to or longer than the threshold time.

[0374] The following will explain Fig.15 The example shown. Fig.15 In the Fig.13 The description of F501 to F508 and F1301 to F1307 which are the same are illustrated, and F1501 to F1506 which are different will be described.

[0375] In F1501, RX sends a power transmission output change request including CEV(0) or CEV(-) to TX. In F1502, TX maintains the transmission power corresponding to CEV(0) or changes (reduces the power) corresponding to CEV(-) in response to the power transmission output change request from RX.

[0376] In F1503, RX changes the setting of the maximum power consumption. RX performs the setting of reducing the maximum power consumption or the setting of the power receiving value currently received from TX. In F1504, TX maintains the power transmission state based on the power transmission control in F1502 in association with the maximum power consumption of RX. On the other hand, RX continues to receive power from TX with the adjusted power in F1505, and maintains the power receiving state in F1506.

[0377] The following will refer to Fig.16 To illustrate the processing on the RX side. Fig.16 In the Fig.14 The description of F1401 to F1408 which are the same are illustrated, and F1601 to F1603 which are different will be described.

[0378] When the judgment condition in S1407 (CEV(+) has been transmitted a number of times equal to or greater than the threshold) or the judgment condition in S1408 (CEV(+) has been transmitted for a time equal to or greater than the threshold) is satisfied, the processing flow enters S1601, and the second power transmission control is performed. The second power transmission control is performed by causing RX to request TX to limit the transmission power, and includes the following two methods.

[0379] In the first method, RX requests TX to maintain the current power transmission operation for the purpose of maintaining power consumption during reception of power. In this case, CE including CEV(0) is transmitted from RX to TX.

[0380] In the second method, RX requests TX to reduce the transmission power for the purpose of setting the maximum power consumption low. In this case, CE including CEV(3) is sent from RX to TX. TX performs control for maintaining or changing (reducing) the transmission power according to CEV(0) or CEV(-) included in CE from RX ( Fig.15 :F1502).

[0381] In S1602 after S1601, RX changes the setting of the maximum power consumption. TX maintains the power transmission state based on the first method or the second method for the maximum power consumption of RX ( Fig.15 : F1504). In S1603, the RX continues to receive power with the adjusted power and limits the transmitted power.

[0382] The basic operation in the second power transmission control includes: communication between TX and RX, setting a power value smaller than a threshold by negotiation, and power transmission from TX to RX. For example, when the minimum power value is set to the GP value and TX transmits power to RX, the power transmission from TX to RX is reduced.

[0383] Even if foreign matter is detected, heat generated from the foreign matter can be reduced. The GP value can be changed according to the value of the coupling coefficient k or the Q factor or the values ​​of the coupling coefficient k and the Q factor, and the TX can transmit power to the RX.

[0384] [Modifications]

[0385] The following will refer to Figures 17 to 20 A modified example of the first embodiment is described. The power receiving device 200 according to the modified example is based on the voltage value Vrect (reference Figure 3 : 214) to determine CEV. The power receiving device 200 determines whether to perform the first power transmission control and the second power transmission control based on Vrect.

[0386] First, we will explain Fig.17 The examples shown are omitted. Fig.13 The description of F501 to F508 and F1301 to F1309 which are the same are illustrated, and F1701 , F1702 , and F1703 which are different will be described.

[0387] In F1701 after F1301, RX measures Vrect of the power receiving unit 203. RX uses the measurement result of Vrect to determine CEV(+), CEV(0), or CEV(-) included in CE as the power transmission output change request. In F1702 after F1304 or F1703 after F1307, the same operation as in F1701 is performed.

[0388] The following will refer to Fig.18 The processing on the RX side will be explained. Fig.14 The description of F1401 to F1409 which are the same are illustrated, and F1801 which is different will be described.

[0389] In S1801 after S1403, RX measures Vrect and uses the measurement result to determine CEV(+), CEV(0) or CEV(-). After S1801, the process flow proceeds to S1404.

[0390] That is, when CE determined to include CEV(+) is transmitted to TX as a result of measuring the power receiving voltage Vrect smaller than the predetermined threshold value for a predetermined time or longer or measuring the power receiving voltage Vrect smaller than the predetermined threshold value a predetermined number of times or more, RX transmits a request for changing to the first power transmission control to TX.

[0391] The following will explain Fig.19 The example shown. Since F501 to F508 and F1301 to F1307 are Fig.15 The same as shown and F1701 to F1703 are Fig.17 The examples are the same, so the description will be omitted. Fig.19 In, after F1703 Fig.15 The operation of F1501 to F1506.

[0392] The following will refer to Fig. 20 To illustrate the processing on the RX side. Fig.18 The differences are as follows.

[0393] - Deleted the processing of S1409.

[0394] - When the judgment condition of S1407 or S1408 is met, the processing of S1601 to S1603 is performed.

[0395] The processing of S1601 to S1603 associated with the second power transmission control is the same as Fig.16 The examples are the same, so their description will be omitted.

[0396] exist Fig. 20 In the embodiment, RX sets the maximum power consumption in S1401 and measures Vrect in S1801. RX determines CEV(+), CEV(0) or CEV(-) based on the measurement result of Vrect.

[0397] As a result of measuring the power receiving voltage Vrect smaller than the predetermined threshold for a predetermined time or more or measuring the power receiving voltage Vrect smaller than the predetermined threshold for a predetermined number of times or more, RX determines whether CE including CEV(+) has been transmitted to TX. When the determination condition is satisfied, RX transmits a request for changing to the second power transmission control to TX.

[0398] RX can judge the system error according to the measurement result of Vrect. For example, it is assumed that as the measurement result of Vrect, a measurement value equal to or greater than a predetermined threshold value is continuously measured. Whether there is a system error can be judged by judging whether a measurement value satisfying the condition is continuously measured for a predetermined time or longer or a measurement value satisfying the condition is continuously measured for a predetermined number of times or more.

[0399] In the modification, the voltage value Vrect of the power receiving unit is used as the power receiving information. The present embodiment is not limited to this example, and CEV(+), CEV(0), or CEV(-) may be determined based on the value of the power receiving current or the power receiving power of the power receiving unit.

[0400] In the present embodiment and the modified example, appropriate power transmission control can be performed in a state where a foreign object is present between the power transmitting device and the power receiving device and in a state other than this state where there is a possibility that the operation of the wireless power transmission system will fail.

[0401] [Second embodiment]

[0402] The following will refer to Figures 21 to 32 The second embodiment of the present disclosure is described below. In this embodiment, a method of detecting a state with higher accuracy using three methods will be described. The three methods include a power loss method, a waveform attenuation method, and a method of measuring the coupling state between a power transmitting antenna and a power receiving antenna. The characteristics of these methods are as follows.

[0403] In the waveform attenuation method, when there is a foreign object (such as a metal piece) between TX and RX, the foreign object can be detected, and the detection accuracy of the misalignment between the power transmitting antenna and the power receiving antenna is low. In the method of measuring the coupling state between the power transmitting antenna and the power receiving antenna and the power loss method, the misalignment between the power transmitting antenna and the power receiving antenna can be detected, and when there is a foreign object (such as a metal piece) between TX and RX, the foreign object can also be detected.

[0404] In this embodiment, in addition to the control in the above-mentioned first embodiment, in cases where it is difficult to judge a system failure of the wireless power transmission system in the first embodiment, or where it is difficult to judge the presence of foreign matter or misalignment, the following control is performed using measurement results based on three methods in addition to the control in the first embodiment.

[0405] An example of using the coupling coefficient k as a coupling state indicator to specifically identify system abnormalities such as failures, foreign matter, or misalignment will be described. The same details in this embodiment as in the first embodiment will be referred to by the same symbols or marks as described above, and their detailed description will be omitted, and the differences will be mainly described.

[0406] The following will refer to Figures 21 to 28 An example of basic operation and control between RX and TX in the present embodiment is explained. As a premise, it is assumed that the threshold used for state judgment in each method is set at a stage before power transmission starts (before the power transmission stage).

[0407] In the power transmitting device or the power receiving device constituting the wireless power transmission system, it is also assumed that situations such as foreign matter or failures change in real time. Therefore, the process of setting the threshold value in each method can be performed in the power transmission stage.

[0408] First, we will explain Fig.21 In F2101, it is assumed that RX measures Vrect smaller than a predetermined threshold value for a predetermined time or longer or measures Vrect smaller than a predetermined threshold value for a predetermined number of times or more. Operation of detecting system abnormality using CEV(+) included in the power transmission output change request and the operation of RX before the operation are different from Fig.17 The operations up to F1703 are the same, so their description will be omitted.

[0409] In F2102, RX stops sending the power transmission output change request including CEV(+). In F2103, RX measures the voltage for calculating the coupling coefficient k based on the first measurement method. When the second measurement method is used, measurement of the voltage on the RX side is not required. Specifically, the values ​​of V2, V4, and V5 are acquired.

[0410] In F2104, TX uses the first measurement method or the second measurement method to measure the voltage used to calculate the coupling coefficient k. Specifically, the values ​​of V1, V3, V6, and V7 are obtained. The measurement of these voltage values ​​can be performed in each of TX and RX when TX sends an analog ping or a digital ping.

[0411] That is, the measurements in F1301, F2104, and F2103 can be performed at the same timing. Therefore, the measurements can be performed in a shorter time.

[0412] When the coupling coefficient k is calculated by TX, in F2105 RX notifies TX of information necessary for calculating the coupling coefficient k.

[0413] Alternatively, when the coupling coefficient k is calculated by RX, TX notifies RX of information required to calculate the coupling coefficient k. The information required to calculate the coupling coefficient is information such as the values ​​of V1 to V7, the values ​​of self-inductances L1 and L2, and constants calculated using the electrical characteristics of the power transmitting antenna or the power receiving antenna.

[0414] In F2106, TX calculates the coupling coefficient k and its threshold. Alternatively, RX may calculate the coupling coefficient k. Regarding the threshold for the coupling coefficient k, use the above reference Fig.10 The first threshold value setting method uses the value of a coupling state index for detecting the state between the power transmitting antenna and the power receiving antenna in a state where there is no state abnormality.

[0415] In F2107, TX notifies RX of the calculated coupling coefficient k and the threshold information of k. In F2108, RX determines whether the value of the coupling coefficient k is within the range based on the threshold information. For example, it is assumed that the value of the coupling coefficient k is equal to or greater than the threshold. In F1308, RX uses an EPT packet to send a power transmission stop request to TX.

[0416] In F1309, TX stops power transmission in response to the power transmission stop request from RX. The power transmission stop request and the operations thereafter are the same as those in the first embodiment, and thus detailed description thereof will be omitted.

[0417] The following will explain Fig. 22 The example shown. Since F2101 to F2107 are Fig.21 The examples are the same, so the description thereof will be omitted, and only the differences will be described. In F2201, RX determines that the value of the coupling coefficient k is smaller than the threshold value based on the coupling coefficient k and the threshold value information of k. The following control is performed to detect the state with higher accuracy.

[0418] In F2202 , RX requests TX to perform a power consumption method associated with a first foreign object detection function. Upon receiving the first foreign object detection request from RX, TX detects foreign objects using a designated foreign object detection method.

[0419] In F2203, TX obtains a judgment result indicating that no foreign matter is detected. In F2204, TX returns an affirmative response (ACK) to RX. In F2205, RX performs the following control when judging that "there is no foreign matter" based on the affirmative response (ACK) from TX. Since the value of the coupling coefficient k is less than the threshold value and the first foreign matter detection result is "there is no foreign matter", RX judges that there is a high possibility that misalignment has occurred.

[0420] In F2205, RX requests TX to perform calibration processing again (recalibration processing). RX checks the preset operation mode information regarding whether to reset the transmission power.

[0421] The operation mode information associated with the power transmission control of RX is set as an initial value at the time of shipment of the product, or is set according to the user's operation instruction after the product has been purchased. In F2206, RX performs calibration processing together with TX again. In the third power transmission control, recalibration processing is performed.

[0422] The following will explain Fig.23 The example shown. Since F2101 to F2107 are Fig.21 The same as shown and F2201 to F2204 are Fig. 22 The examples are the same, so their description will be omitted, and only the differences will be described.

[0423] In F2301 after F2204, RX determines whether an alarm associated with misalignment must be notified to the user. The setting of the alarm notification associated with misalignment of RX relative to TX is set to an initial value at the time of shipment of the product, etc., or is set according to the user's operation instruction after the product has been purchased.

[0424] When the alarm notification is set, the RX performs a notification process to prompt the user to realign the RX with the TX. This process can be realized by outputting various types of information to the user using the UI unit 202, for example.

[0425] The output of various types of information includes operations such as screen display on a liquid crystal panel, blinking or color change of an LED, output of sound from a speaker, and vibration of the main body of the RX using a vibration motor. When the RX is located at the optimal position on the TX through this alarm notification, the possibility that power will be appropriately transmitted from the TX to the RX becomes higher.

[0426] The power transmission limitation processing in F1501 to F1506 after F2301 is the same as the second power transmission control in the first embodiment, and thus a detailed description thereof will be omitted.

[0427] The following will explain Fig.24 The example shown. Since F2101 to F2107 are Fig.21 The same as shown and F2201 to F2204 are Fig. 22 The examples are the same, so their description will be omitted, and only the differences will be described.

[0428] In F2401, RX determines whether to notify the user of an alarm associated with misalignment with respect to TX. When the alarm notification is not set, the power transmission control mode is checked.

[0429] In the power transmission control mode, the first power transmission control or the second power transmission control described above in the first embodiment is set. The power transmission control mode is set as an initial value at the time of shipment of the product, etc., or is set according to the user's operation instruction after the product has been purchased. When the first power transmission control is set in the power transmission control mode, in F1308, RX sends EPT as a power transmission stop request to TX. In F1309, TX performs power transmission stop processing.

[0430] The following will explain Fig.25 The example shown. Since F2101 to F2107 are Fig.21 The same as shown and F2201 to F2202 are Fig. 22 The examples are the same, so their description will be omitted, and only the differences will be described.

[0431] After F2202, when TX determines that a foreign object is detected in F2501, TX returns a negative response (NAK) to RX in F2502. When a negative response (NAK) is received from TX in F2502, RX determines that "a foreign object is present".

[0432] The RX checks whether the system setting has been set to perform the second foreign matter detection process. The setting indicating whether to perform the second foreign matter detection is set as an initial value at the time of shipment of the product, etc., or is set according to the user's operation instruction after the product has been purchased.

[0433] If the second foreign object detection is not set (not performed), in F2503, RX (or TX) performs a process of notifying the user of foreign object detection. This notification process is a notification process that prompts the user to remove the foreign object between the power transmitting antenna and the power receiving antenna or on the power transmitting antenna.

[0434] This can be achieved, for example, by outputting various types of information to the user using the UI unit 202 of the RX. The output of various types of information includes operations such as screen display on a liquid crystal panel, blinking or color change of an LED, output of voice from a speaker, and vibration of the main body of the RX using a vibration motor.

[0435] The output of various types of information in F2503 is set to be different from the output of various types of information in F2301, and control is performed to enable the user to distinguish between the two outputs. Therefore, the user can clearly determine whether there is a possibility that misalignment between the power transmitting antenna and the power receiving antenna has occurred, or whether there is a possibility that foreign matter exists between the power transmitting antenna and the power receiving antenna.

[0436] When the foreign object is removed by notification of the user, the possibility that power will be more appropriately transmitted from TX to RX becomes higher. Alternatively, TX may have the same function as the UI unit 202 of RX and notify the user to prompt the removal of the foreign object on TX. Then, F1501 to F1506 performed between RX and TX are the same as Fig.23 The examples are the same, so their detailed description will be omitted.

[0437] The following will explain Fig.26 The example shown. Since F2101 to F2107 are Fig.21 The same as shown and F2201 and F2202 are Fig. 22 The same as shown, and F2501 and F2502 are Fig.25 The examples are the same, so their description will be omitted, and only the differences will be described.

[0438] When the first power transmission control is set in the power transmission control mode, in F2601, similar to F2503, RX performs notification processing. F1308 and F1309 performed between RX and TX are the same as those mentioned above. Fig.21 The above-described first power transmission control is the same, and thus a detailed description thereof will be omitted.

[0439] The following will explain Fig. 27 The example shown. Since F2101 to F2107, F2201, F2202, F2501 and F2502 are Fig.26 The examples are the same, so their description will be omitted, and only the differences will be described.

[0440] After F2502, in F2701, TX prepares to measure a threshold value for performing second foreign matter detection. It is assumed that the second foreign matter detection is, for example, foreign matter detection based on a measurement result of a waveform attenuation index using a waveform attenuation method, and uses a Q factor as a waveform attenuation index.

[0441] The second foreign object detection is performed after the first foreign object detection, but can be performed on time as needed so that the measurement is performed in advance at a timing immediately after the start of power transmission. In the following description, the measurement of the waveform attenuation index based on the waveform attenuation method for the second foreign object detection is referred to as "Q factor measurement".

[0442] In F2701, TX measures the Q factor, and in F2702, RX requests execution of the second foreign matter detection. In F2703, TX acquires a judgment result indicating that "there is no foreign matter", and in F2704, TX returns an affirmative response (ACK) to RX.

[0443] When receiving an acknowledgement (ACK) from TX, RX determines that "there is no foreign object". Fig. 27 In the illustrated example, “foreign matter exists” as a result of the first foreign matter detection and “foreign matter does not exist” as a result of the second foreign matter detection conflict with each other.

[0444] Therefore, it is determined that a system error has occurred between RX and TX and the power transmission stop process is performed in consideration of safety. In the following description, F1308 and F1309 performed between RX and TX are the same as those in the above reference. Fig.21 The above-described first power transmission control is the same, and thus a detailed description thereof will be omitted.

[0445] The following will explain Fig.28 The example shown. Since F2101 to F2702 are Fig. 27TX obtains a determination result indicating "there is a foreign object" in the second foreign object detection in F2801, and returns a negative response (NAK) to RX in F2802.

[0446] When receiving a negative response (NAK) from TX, RX determines that "foreign matter is present", and in F2503, RX (or TX) performs processing to notify the user of foreign matter detection. Fig.28 In the illustrated example, “there is a foreign object” as a result of the first foreign object detection and “there is a foreign object” as a result of the second foreign object detection do not conflict with each other.

[0447] Notification processing is the same as above Fig.25 In the following description, F1501 to F1506 are connected between RX and TX. Fig.25 The examples are the same as those shown in , so their detailed description will be omitted.

[0448] Fig.29 and Fig.30 : is a flowchart illustrating the processing on the RX side in the basic operation and control between RX and TX according to the present embodiment. Fig.29 The processing of S1401, S1402 and S1405 in Fig.14 and Fig.18 The examples are the same, so their detailed description is omitted.

[0449] If the target power is not set in S1402, the RX performs a check of the power based on the power receiving voltage Vrect and transmits a request for changing the power transmission output in S2900. The check of the power based on Vrect is performed using the power output of the RX. Fig.18 The power transmission output change request is sent in the same manner as in S1801. Fig.14 After S2900, the processing flow enters S1405.

[0450] When the judgment condition of S1405 is satisfied, the processing flow enters S2901. In S2901, a process of checking the change of the power transmission output is performed. This process is the same as the above process in Fig.14 The same as described in S1406 to S1408.

[0451] Then, in S2902, RX notifies TX, which calculates the coupling coefficient k, of information necessary for calculating the coupling coefficient k (such as voltage value, self-inductance value, and constants calculated using electrical characteristics of the power transmitting antenna or the power receiving antenna). After S2902, the processing flow proceeds to S2903.

[0452] In S2903, RX compares the coupling coefficient k obtained from TX with its threshold information. If the value of the coupling coefficient k is equal to or greater than the threshold (S2903: Yes), the processing flow enters Fig.30 In S2911 in. In the case where the value of the coupling coefficient k is smaller than the threshold value (S2903: No), the processing flow proceeds to S2904 to detect the state with higher accuracy.

[0453] In S2904, RX requests TX to perform the power loss method as the first foreign object detection function (FODS1). Fig.30 In S2905, RX determines whether "foreign matter exists". When receiving a negative response (NAK) from TX, RX determines that "foreign matter exists" (S2905: Yes), and the processing flow enters S2906. When RX determines that "foreign matter does not exist" (S2905: No), the processing flow enters S2912.

[0454] In S2906, the RX determines whether the system is set to perform the second foreign object detection process (FOD2). When the execution of the second foreign object detection process is set (S2906: Yes), the processing flow enters S2907. When the execution of the second foreign object detection process is not set (S2906: No), the processing flow enters S2909.

[0455] In S2907, RX requests TX to perform the second foreign object detection (FOD2). RX requests TX to perform foreign object detection using the waveform attenuation method. Then, in S2908, RX determines whether "foreign object exists".

[0456] When receiving a negative response (NAK) from TX, RX determines that "foreign object exists" (S2908: Yes), and the process flow enters S2909. When receiving an affirmative response (ACK) from TX, RX determines that "foreign object does not exist" (S2908: No), and the process flow enters S2911.

[0457] In S2909, RX performs notification processing associated with the detection of foreign objects based on the result of foreign object detection. For example, RX performs an alarm notification processing to prompt the user to remove foreign objects between the power transmitting antenna and the power receiving antenna or on the power transmitting antenna. After S2909, the processing flow enters S2910.

[0458] In S2910, RX determines whether the first power transmission control is set in the power transmission control mode. The first power transmission control is a control for stopping power transmission from TX to RX, and when the first power transmission control is set, the processing flow enters S2911. When the first power transmission control is not set (when the second power transmission control is set), the processing flow enters S2915.

[0459] In S2911, RX performs power transmission stop processing together with TX. For example, RX determines that there is a possibility that a system error has occurred and sends an EPT packet to TX. Then, the processing flow ends.

[0460] In S2912, RX determines whether to reset power. When the result of foreign matter detection in S2905 does not indicate "foreign matter exists" and there is a high possibility that misalignment has occurred, RX determines whether to perform calibration again and reset the transmission power based on the operation mode information.

[0461] When the operation mode information indicates that the power is to be reset (S2912: Yes), RX advances the process flow to S2916. When the operation mode information indicates that the power is not to be reset (S2912: No), RX advances the process flow to S2913.

[0462] In step S2913, the RX determines whether to perform an alarm notification of the misalignment detection result. When the alarm notification is set (S2913: Yes), the processing flow proceeds to S2914. When the alarm notification is not set (S2913: No), the processing flow proceeds to S2910.

[0463] In S2914, the RX performs a notification process based on the result of the misalignment detection, and notifies the user of an alarm for prompting the user to realign the RX with the TX.

[0464] In S2915 after S2914, RX and TX perform power transmission restriction processing. The power transmission restriction processing is the same as the second power transmission control described above in the first embodiment. Then, the processing flow ends.

[0465] In S2916, RX performs a recalibration process. RX sends a message to TX for requesting execution of the recalibration process. Then, the process flow ends.

[0466] Fig.31 and Fig.32 1 is a flowchart illustrating the processing on the TX side associated with the basic operation and control between the RX and the TX in the present embodiment. In S3001, the TX measures a voltage for calculating a coupling coefficient k based on the first measurement method or the second measurement method.

[0467] In S3002, TX determines whether a request for measurement of the coupling coefficient k is received from RX. When a request for calculating the coupling coefficient k (or sending the required information) is received from RX (S3002: Yes), TX advances the processing flow to S3003. Alternatively, when it is determined that no request for measurement is received, the determination process of S3002 is repeated.

[0468] In S3003, TX calculates the coupling coefficient k and the threshold value of k. Then, in S3004, TX notifies RX of the coupling coefficient k and the threshold value information of k calculated in S3003. Then, in S3005, TX determines whether a message is received from RX.

[0469] When it is determined that a message has been received from the RX (S3005: Yes), the processing flow proceeds to S3006. When it is determined that a message has not been received from the RX, the determination process of S3005 is repeated.

[0470] In S3006, TX determines whether a request for the first foreign object detection is received from RX. When TX receives a request for the first foreign object detection (S3006: Yes), the processing flow enters S3007, and when TX determines that a request for the first foreign object detection is not received (S3006: No), the processing flow enters Fig.32 S3012.

[0471] In S3007, TX uses the specified first foreign matter detection method to detect foreign matter. Then, in S3008, TX determines whether foreign matter is detected. When it is determined that foreign matter is detected (S3008: Yes), TX causes the processing flow to enter S3009. When it is determined that foreign matter is not detected (S3008: No), the processing flow enters S3011.

[0472] In S3009, TX returns a negative response (NAK) to RX. Then, in S3010, TX determines whether to prepare for the second foreign object detection measurement. When it is determined that the measurement is to be prepared (S3010: Yes), TX advances the processing flow to S3019.

[0473] When it is determined that the measurement is not to be performed (S3010: No), the process flow proceeds to S3005 for the purpose of continuing to execute other control related to power transmission. TX returns an affirmative response (ACK) to RX in S3011, and then proceeds to S3005.

[0474] In S3019, TX prepares to measure the threshold used for the second foreign body detection, and then performs the measurement. Specifically, the Q factor is measured. After S3019, the processing flow enters S3005.

[0475] exist Fig.32 In S3012, TX determines whether a power transmission output change request is received from RX. When it is determined that a power transmission output change request is received (S3012: Yes), the processing flow proceeds to S3013. When it is determined that a power transmission output change request is not received (S3012: No), the processing flow proceeds to S3015.

[0476] In S3013, TX performs a power transmission power change process in response to the power transmission output change request from RX. Then, in S3014, TX determines whether the power transmission power has been confirmed. When it is determined that the power transmission power has been confirmed (S3014: Yes), the process flow of resetting the maximum power consumption ends. When it is determined that the power transmission power has not been confirmed (S3014: No), the process flow enters Fig.31 S3005.

[0477] In S3015, TX determines whether a request for recalibration processing is received from RX. When it is determined that a request for recalibration processing is received (S3015: Yes), the process flow proceeds to S3016, and when it is determined that a request for recalibration processing is not received (S3015: No), the process flow proceeds to S3017.

[0478] In S3016, TX performs a recalibration process together with RX, and then ends the process flow. In S3017, TX determines whether or not EPT, which is a power transmission stop request, is received from RX.

[0479] When it is determined that the EPT is received (S3017: Yes), the processing flow enters S3018, and when it is determined that the EPT is not received (S3017: No), the processing flow enters Fig.31 In S3018, TX stops the power transmission to RX by stopping the power supply from the power supply unit 102 to the power transmission unit 103, and ends the processing flow.

[0480] In the present embodiment, appropriate power transmission control (which includes stop of power transmission, limitation of power, or resetting of power) can be performed without easily identifying whether a system error during wireless power transmission is based on foreign matter or device failure.

[0481] [Other embodiments]

[0482] The present disclosure may also be implemented by the following process: a program for implementing one or more functions of the above-mentioned embodiments is provided to a system or device via a network or storage medium, and one or more processors in a computer of the system or device read and execute the program. The present disclosure may also be implemented by a circuit (e.g., ASIC) for implementing one or more functions.

[0483] Although the present invention has been described in detail above in conjunction with typical embodiments of the present invention, the present invention is not limited to these embodiments and can be modified in various ways based on the gist of the present invention (these modifications are not excluded from the scope of the present invention). The present invention includes a combination of a plurality of embodiments.

[0484] (CROSS-REFERENCE TO RELATED APPLICATIONS)

[0485] Priority is claimed on Japanese Patent Application No. 2022-132613 filed on August 23, 2022. The contents of this Japanese Patent Application are incorporated herein by reference.

Claims

1. A power receiving device, comprising: a power receiving component configured to wirelessly receive power from the power transmitting device; a communication component configured to communicate with the power transmission device; as well as a control unit configured to perform control for transmitting, via the communication unit, a first request for changing or maintaining a power transmission output to the power transmission device, In which, when the first request for increasing the power transmission output of the power transmission device has been sent to the power transmission device a predetermined number of times or more or has been continuously sent to the power transmission device for a predetermined time or longer, the control component performs control for sending a second request for changing the power transmission control to the power transmission device via the communication component.

2. The power receiving device according to claim 1, wherein: The first request is transmitted using a signal associated with a change or maintenance of a power receiving voltage, a power receiving current, or a power receiving power of the power receiving component, and the signal includes difference information indicating a difference between a current operating point and a target operating point of the power receiving device.

3. The power receiving device according to claim 1, wherein: The second request is a request for changing to a first power transmission control for stopping power transmission from the power transmitting device, a second power transmission control for limiting power transmission from the power transmitting device, or a third power transmission control for resetting power consumption in the power receiving device.

4. The power receiving device according to claim 3, wherein: In the second power transmission control, maximum power consumption in the power receiving device is restricted.

5. The power receiving device according to claim 3, wherein: The second request includes information indicating a reason for the first power transmission control.

6. The power receiving device according to claim 2, wherein: The control means continues receiving electric power by performing control for transmitting the first request that the difference information is zero or a negative value to the electric power transmitting device.

7. The power receiving device according to claim 2, wherein: The control means determines the difference information based on received power information of the power receiving means.

8. The power receiving device according to claim 7, wherein: The control means performs control for transmitting, using the communication means, the first request for increasing the power transmission output of the power transmitting device, which is determined when the value of the received power information is smaller than a threshold value.

9. A power transmitting device capable of wirelessly transmitting power to a power receiving device, the power receiving device comprising: a power receiving component configured to wirelessly receive power from the power transmitting device; a communication component configured to communicate with the power transmission device; and a control unit configured to perform control for transmitting, via the communication unit, a first request for changing or maintaining a power transmission output for the power transmission device, wherein, in a case where the first request for increasing the power transmission output of the power transmission device has been transmitted to the power transmission device a predetermined number of times or more or has been continuously transmitted to the power transmission device for a predetermined time or more, the control unit performs control for transmitting, via the communication unit, a second request for changing power transmission control to the power transmission device, the power transmission device comprising: a communication component, configured to communicate with the powered device; and A control means is configured to, when receiving the second request from the power receiving apparatus through the communication means, make a change to power transmission control corresponding to the second request.

10. A wireless power transmission system, comprising: A power receiving device, comprising: a power receiving unit configured to wirelessly receive power from a power transmitting device; a communication unit configured to communicate with the power transmitting device; and a control unit configured to perform control for sending, via the communication unit, a first request for changing or maintaining a power transmission output to the power transmitting device, wherein, in a case where the first request for increasing the power transmission output of the power transmitting device has been sent to the power transmitting device a predetermined number of times or more or has been continuously sent to the power transmitting device for a predetermined time or longer, the control unit performs control for sending, via the communication unit, a second request for changing power transmission control to the power transmitting device; and A power transmitting device includes: a communication unit configured to communicate with the power receiving device; and a control unit configured to change the power transmission control to correspond to the second request when the second request is received from the power receiving device through the communication unit.

11. The wireless power transmission system according to claim 10, further comprising a measuring unit configured to measure a coupling state index indicating an electromagnetic coupling state between a power transmitting antenna of the power transmitting device and a power receiving antenna of the power receiving device, in, In response to the second request based on a comparison result between the coupling state index measured by the measuring section and a threshold value of the coupling state index, a process for changing the power transmission control is performed.

12. The wireless power transmission system according to claim 11, wherein: When the measured value of the coupling state index is equal to or greater than the threshold value, the power transmitting device performs a first power transmission control for stopping power transmission in response to the second request from the power receiving device.

13. The wireless power transmission system according to claim 11, wherein: When the measured value of the coupling state index is smaller than the threshold value, the power transmitting device performs second power transmission control for limiting power transmission from the power transmitting device and continuing power transmission in response to the second request from the power receiving device.

14. The wireless power transmission system according to claim 11, further comprising a detection component configured to detect an object different from the power transmitting device and the power receiving device, in, When the measured value of the coupling state indicator is less than the threshold value, the power receiving device requests the power transmitting device to detect an object using the detection component, and When it is determined that the object is not detected by the detection means, the power receiving device transmits the second request for changing to a third power transmission control for resetting power consumption to the power transmitting device.

15. The wireless power transmission system according to claim 11, further comprising a detection component configured to detect an object different from the power transmitting device and the power receiving device, in, When the measured value of the coupling state indicator is less than the threshold value, the power receiving device requests the power transmitting device to detect an object using the detection component, wherein, when it is determined that the object is not detected by the detection means, the power receiving device or the power transmitting device performs processing for notifying the power receiving device of misalignment with respect to the power transmitting device; and When it is determined that no object is detected by the detection means, the power receiving device sends the second request for changing to a second power transmission control for limiting power transmission from the power transmitting device and continuing to transmit power to the power transmitting device.

16. The wireless power transmission system according to claim 11, further comprising a detection component configured to detect an object different from the power transmitting device and the power receiving device, in, When the measured value of the coupling state indicator is less than the threshold value, the power receiving device requests the power transmitting device to detect an object using the detection component, and When it is determined that no object is detected by the detection means, the power receiving device sends the second request for changing to a first power transmission control for stopping power transmission from the power transmitting device to the power transmitting device.

17. The wireless power transmission system according to claim 11, further comprising a detection component configured to detect an object different from the power transmitting device and the power receiving device, in, When the measured value of the coupling state indicator is less than the threshold value, the power receiving device requests the power transmitting device to detect an object using the detection component, wherein, when it is determined that an object is detected by the detection means, the power receiving device or the power transmitting device performs processing for notifying that an object is detected, and When it is determined that an object is detected by the detection means, the power receiving device sends the second request for changing to a second power transmission control for limiting power transmission from the power transmitting device and continuing to transmit power to the power transmitting device.

18. The wireless power transmission system according to claim 11, further comprising a detection component configured to detect an object different from the power transmitting device and the power receiving device, in, When the measured value of the coupling state indicator is less than the threshold value, the power receiving device requests the power transmitting device to detect an object using the detection component, wherein, when it is determined that an object is detected by the detection means, the power receiving device or the power transmitting device performs processing for notifying that an object is detected, and When it is determined that an object is detected by the detection means, the power receiving device sends the second request for changing to a first power transmission control for stopping power transmission from the power transmitting device to the power transmitting device.

19. The wireless power transmission system according to claim 11, further comprising: a first detection component configured to detect an object different from the power transmitting device and the power receiving device; as well as a second detection component configured to detect an object using a method different from that of the first detection component, Wherein, when the measured value of the coupling state indicator is less than the threshold value, the power receiving device requests the power transmitting device to detect an object using the first detection component, wherein, when an object is detected by the first detection component, the power receiving device requests the power transmitting device to detect the object by the second detection component, and When it is determined that no object is detected by the second detection means, the power receiving device sends the second request for changing to a first power transmission control for stopping power transmission from the power transmitting device to the power transmitting device.

20. The wireless power transmission system according to claim 11, further comprising: a first detection component configured to detect an object different from the power transmitting device and the power receiving device; as well as a second detection component configured to detect an object using a method different from that of the first detection component, Wherein, when the measured value of the coupling state indicator is less than the threshold value, the power receiving device requests the power transmitting device to detect an object using the first detection component, wherein, when an object is detected by the first detection means, the power receiving device requests the power transmitting device to detect the object by the second detection means, wherein, when it is determined that an object is detected by the second detection unit, the power receiving device or the power transmitting device performs processing for notifying that the object is detected, and When it is determined that an object is detected by the second detection means, the power receiving device sends the second request for changing to a second power transmission control for limiting power transmission from the power transmitting device and continuing to transmit power to the power transmitting device.

21. The wireless power transmission system according to claim 19, wherein: The first detection unit detects an object based on power loss between the power transmitting device and the power receiving device, and The second detection unit detects the object by measuring a quality factor of a power transmission antenna of the power transmission device.

22. A communication method for a power receiving device capable of receiving power from a power transmitting device by wireless power transmission, the communication method comprising the following steps: sending a first request to change or maintain a power transmission output to the power transmitting device; as well as When the first request for increasing the power transmission output of the power transmission device has been sent to the power transmission device a predetermined number of times or more or has been continuously sent to the power transmission device for a predetermined time or more, a second request for changing power transmission control is sent to the power transmission device.

23. A wireless power transmission method for transmitting power from a power transmitting device to a power receiving device, the wireless power transmission method comprising the following steps: causing the power receiving device to send a first request for changing or maintaining a power transmission output to the power transmitting device; causing the power receiving device to send a second request for changing power transmission control to the power transmitting device when the first request for increasing the power transmission output of the power transmitting device has been sent from the power receiving device to the power transmitting device a predetermined number of times or more or has been continuously sent from the power receiving device to the power transmitting device for a predetermined time or more; as well as The power transmitting device is caused to change to power transmission control corresponding to the second request received from the power receiving device.

24. A computer program for causing a computer to perform the following steps: sending a first request for changing or maintaining a power transmission output to a power transmitting device performing wireless power transmission; and When the first request for increasing the power transmission output of the power transmission device has been sent to the power transmission device a predetermined number of times or more or has been continuously sent to the power transmission device for a predetermined time or more, a second request for changing power transmission control is sent to the power transmission device.

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