Power transmission apparatus and computer readable storage medium

Abstract

The invention relates to a power transmission apparatus and a computer readable storage medium. A power transmission device configured to wirelessly transmit power to a power receiving device performs: a detection process for detecting an object different from the power receiving device using a power loss when wireless power transmission is performed; obtaining, from the power receiving device, reference value information relating to a reference value of the received power for obtaining the power loss; and performing a predetermined control after the power loss has been obtained and when a predetermined time has elapsed since a predetermined timing associated with the timing at which the information is obtained from the power receiving device and in a case where valid reference value information has not been obtained, the predetermined control is a control that prevents an increase in the power transmission output regardless of the received power in the power receiving device.

Description

[0001] (This application is a divisional application of the application with the filing date of August 31, 2020, the application number of 2020800621547, and the invention title of "Power transmission device, control method, and computer-readable storage medium".) Technical Field

[0002] The present invention relates to a technique for controlling transmitted power and received power in wireless power transmission. Background Art

[0003] Techniques for wireless power transmission systems have been widely developed. Patent Document 1 describes a method by which a foreign object that is an object different from a power receiving device is detected during power transmission and reception that conforms to a standard (WPC standard) defined by the Wireless Power Consortium (WPC), which is a standardization organization for wireless charging. In this method, the received power at a past time point and the received power at the current time point are compared, and when the received power does not increase despite the fact that control for increasing the transmitted power has been performed, or when the received power does not decrease despite the fact that control for decreasing the transmitted power has been performed, it is determined that a foreign object is present.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2015-165761 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] It is conceivable that, for example, due to changes in the power transmission and reception environment, even when the same power is transmitted, the received power gradually changes. At this time, if information at a past time point is used for foreign object detection despite the fact that there is a significant time difference between the past time point and the current time point, the accuracy of foreign object detection may decrease. This may cause various problems that reduce convenience, such as charging stop due to false detection and temperature rise caused by failure to detect a foreign object that is present.

[0009] Solutions to the Problems

[0010] The present invention provides a technique for improving the convenience of wireless power transmission.

[0011] A power transmission device according to an aspect of the present invention includes: a power transmission component for wirelessly transmitting power to a power receiving device; a communication component for communicating with the power receiving device; a processing component for performing a detection process for detecting an object different from the power receiving device using power loss when wirelessly transmitting power using the power transmission component; an acquisition component for obtaining reference value information related to a reference value of received power for obtaining the power loss from the power receiving device using the communication component; and a control component for performing specific control when the power loss is obtained and when a predetermined time has elapsed in a state where valid reference value information has not been obtained since a predetermined timing associated with the timing of obtaining information from the power receiving device, the specific control being control for preventing an increase in the output power of the power transmission component regardless of the received power of the power transmission device.

[0012] Effects of the Invention

[0013] According to the present invention, the convenience of wireless power transmission can be improved.

[0014] Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings. Note that throughout the drawings, the same reference numerals denote the same or similar components. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings included in the specification and constituting a part of the specification illustrate embodiments of the present invention and, together with the specification, are used to explain the principles of the present invention.

[0016] Figure 1 is a diagram showing the structure of a wireless charging system.

[0017] Figure 2 is a diagram showing an example of the structure of a power receiving device.

[0018] Figure 3 is a diagram showing an example of the structure of a power transmission device.

[0019] Figure 4 is a flowchart exemplifying an example of the process flow executed by the power transmission device.

[0020] Figure 5 is a flowchart exemplifying an example of the power transmission control process executed by the power transmission device.

[0021] Figure 6A is a flowchart exemplifying an example of the timeout process executed by the power transmission device.

[0022] Figure 6B is a flowchart exemplifying an example of the timeout process executed by the power transmission device.

[0023] Figure 7 It is a flowchart exemplifying the process executed by the power receiving device.

[0024] Figure 8 It is a flowchart exemplifying the process of the power receiving control process executed by the power receiving device.

[0025] Figure 9A It is a diagram showing the communication sequence in the calibration phase.

[0026] Figure 9B It is a diagram showing the communication sequence used for device authentication.

[0027] Figure 10A It is a diagram showing the first example of the process executed in the system.

[0028] Figure 10B It is a diagram showing the first example of the process executed in the system.

[0029] Figure 11A It is a diagram showing the second example of the process executed in the system.

[0030] Figure 11B It is a diagram showing the second example of the process executed in the system. Detailed Description of the Invention

[0031] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments are not intended to limit the scope of the claimed invention. In these embodiments, multiple features are described, but the invention is not limited to an invention that requires all of these features, and multiple such features can be appropriately combined. In addition, in the drawings, the same reference numerals are given to the same or similar structures, and redundant descriptions of these structures are omitted.

[0032] (Structure of the System)

[0033] Figure 1Shows a structural example of a wireless charging system (wireless power transfer system) according to the present embodiment. In the example, the system includes a power receiving device 101 and a power transmitting device 102. Hereinafter, the power receiving device 101 may be referred to as "RX", and the power transmitting device 102 may be referred to as "TX". The RX is an electronic device that receives power from the power transmitting device 102 and charges an internal battery. The TX is an electronic device that wirelessly transmits power to the RX placed on the charging stand 103. The range 104 indicates the range within which the RX can receive power transmitted from the TX. The RX and TX may have functions for executing applications other than wireless charging. An example of the RX is a smart phone, and an example of the TX is an accessory device for charging the smart phone. Each of the RX and TX may be a storage device such as a hard disk device and a memory device, or may be an information processing device such as a personal computer (PC). Alternatively, each of the RX and TX may be an image input device such as a imaging device (camera, video camera, etc.) and a scanner, or may be an image output device such as a printer, a copier, and a projector. Alternatively, the TX may be a smart phone. In this case, the RX may be another smart phone, or may be a peripheral device such as a wireless earphone. Alternatively, the RX may be a car. Alternatively, the TX may be a charger installed in a console or the like inside the car.

[0034] This system performs wireless power transfer using the electromagnetic induction method for wireless charging according to the WPC standard defined by the Wireless Power Consortium (WPC). That is, the RX and TX perform wireless power transfer for wireless charging according to the WPC standard between the power receiving coil of the RX and the power transmitting coil of the TX. The method of wireless power transfer is not limited to the method defined in the WPC standard, and may be another electromagnetic induction method, magnetic resonance method, electric field resonance method, microwave method, or a method using laser or the like. Although wireless power transfer is used for wireless charging in the present embodiment, wireless power transfer may be performed for purposes other than wireless charging.

[0035] In the WPC standard, the power guaranteed when the RX receives power from the TX is defined by a value called "guaranteed power" (hereinafter referred to as "GP"). The GP represents a value of the power output to a load such as a charging circuit in the RX, which is guaranteed even when the power transmission efficiency between the power receiving coil and the power transmitting coil decreases due to, for example, a change in the positional relationship between the RX and the TX. For example, when the GP is 5W, even if the power transmission efficiency decreases due to a change in the positional relationship between the power receiving coil and the power transmitting coil, the TX performs power transmission while controlling so that 5W can be output to the load in the RX.

[0036] The RX and TX according to this embodiment perform communication for power transmission / reception control according to the WPC standard and communication for device authentication. Here, communication for power transmission / reception control according to the WPC standard will be described.

[0037] The WPC standard defines multiple phases (including a power transmission phase for performing power transmission and a phase before actual power transmission), and performs communication for power transmission / reception control required for each phase. The phase before power transmission includes a selection phase, a Ping phase, a configuration phase, a negotiation phase, and a calibration phase. In the selection phase, the TX intermittently transmits an analog Ping and detects the presence of an object within the power transmission range (for example, a power receiving device 101 or a conductor bar is placed on the charging stand 103). In the Ping phase, the TX transmits a digital Ping and identifies the detected object as an RX by receiving a response from the RX that has received the digital Ping. In the configuration phase, the RX notifies the TX of identification information and capability information. In the negotiation phase, negotiation is performed to determine the value of GP based on the value of GP requested from the RX or the power transmission capability of the TX, etc. In the calibration phase, the RX notifies the TX of the received power value according to the WPC standard, and the TX performs adjustment for foreign object detection during power transmission. In the power transmission phase, control for continuing power transmission and stopping power transmission due to an error or full charge is performed, for example. The TX and RX use in-band communication to perform communication for these power transmission and reception controls, where in this in-band communication, signals are superimposed using the same antenna (coil) used for wireless power transmission according to the WPC standard. The range within which in-band communication according to the WPC standard can be performed between the TX and RX is substantially the same as the power transmission range. That is, in Figure 1 , the range 104 represents the range within which wireless power transmission and in-band communication can be performed using the power transmission coil and power reception coil of the TX and RX. In the following description, "placing" the RX means that the RX has entered within the range 104, and includes a state where the RX is not actually placed on the charging stand 103.

[0038] The TX and RX can use an antenna (coil) different from the antenna (coil) used for wireless power transmission to perform communication for power transmission / reception control (out-of-band communication). Examples of communication using an antenna (coil) different from the antenna (coil) used for wireless power transmission include a communication method compliant with the Bluetooth (registered trademark) low power consumption standard. Optionally, other communication methods such as the IEEE 802.11 standard wireless LAN (e.g., Wi-Fi (registered trademark), ZigBee, and NFC (near field communication)) can be used. Communication using an antenna (coil) different from the antenna (coil) used for wireless power transmission can be performed at a frequency different from the frequency used for wireless power transmission.

[0039] In this embodiment, before determining the GP, the RX and the TX perform challenge - response communication using an electronic certificate, and device authentication of the TX is performed. That is, the RX performs communication for device authentication of the TX. Then, based on the result of the device authentication, the RX determines the GP requested from the TX in the above negotiation phase. For example, the RX determines the GP requested from the TX with successful device authentication as 15W, and the GP requested from the TX with unsuccessful device authentication as 5W. The GPs requested from the TX are not limited to the combination of 15W and 5W. For example, any combination of the following values can be used, and among these arbitrary values, the GP requested from the TX with successful device authentication is greater than the GP requested from the TX with unsuccessful device authentication. Therefore, the RX can perform power transmission / reception with a large GP only with the TX having successful device authentication. By determining the GP based on the result of the device authentication in this way, the RX can receive power with a large GP only from the TX that has passed a predetermined test defined in the WPC standard or the like and is considered capable of transmitting power with a large GP.

[0040] (Device Structure)

[0041] Next, the structures of the power receiving device 101 (RX) and the power transmitting device 102 (TX) according to this embodiment will be described. The components described below are merely examples. Some (possibly all) of the described components can be replaced by another structure serving the same function, or can be omitted, and more components can be added to the described components. In addition, one block described in the following description can be divided into multiple blocks, and multiple blocks can be integrated into one block.

[0042] Figure 2 FIG. is a diagram showing an example of the structure of the RX according to this embodiment. In the example, the RX includes a control unit 201, a battery 202, a power receiving unit 203, a detection unit 204, a power receiving coil 205, a communication unit 206, a display unit 207, an operation unit 208, a memory 209, a timer 210, and a charging unit 211.

[0043] The control unit 201 performs overall control of the RX by executing, for example, a control program stored in the memory 209. In the example, the control unit 201 performs device authentication in the RX and the control required for power reception. The control unit 201 may perform control for executing applications other than wireless power transfer. The control unit 201 includes, for example, one or more processors such as a central processing unit (CPU) and a microprocessing unit (MPU). The control unit 201 may include hardware dedicated to specific processing (such as an application specific integrated circuit (ASIC), etc.), and an array circuit (such as a field programmable gate array (FPGA), etc.) compiled to execute a predetermined process. The control unit 201 causes the memory 209 to store information to be stored when various processes are being executed. In addition, the control unit 201 may use the timer 210 to measure time.

[0044] The battery 202 supplies power required for control, power reception, and communication to the entire RX. In addition, the battery 202 stores the power received via the power reception coil 205. In the power reception coil 205, an induced electromotive force is generated by the electromagnetic wave transmitted from the power transmission coil 305 of the TX, and the power reception unit 203 obtains the power generated in the power reception coil 205. The power reception unit 203 obtains AC power generated by electromagnetic induction in the power reception coil 205. Then, the power reception unit 203 converts the AC power into DC power or AC power of a predetermined frequency, and outputs the power to the charging unit 211 that performs a process for charging the battery 202. That is, the power reception unit 203 supplies power to the load of the RX. The above GP is the power guaranteed to be output from the power reception unit 203.

[0045] The detection unit 204 detects whether the RX is placed in the range 104 where power can be received from the RX according to the WPC standard. For example, the detection unit 204 detects the voltage value or current value of the power reception coil 205 when the power reception unit 203 receives a digital Ping of the WPC standard via the power reception coil 205. For example, if the voltage drops below a predetermined voltage threshold, or the current value exceeds a predetermined current threshold, the detection unit 204 may determine that the RX is placed in the range 104.

[0046] The communication unit 206 performs control communication with the TX according to the WPC standard described above using in-band communication. The communication unit 206 demodulates the electromagnetic wave input from the power reception coil 205 to obtain the information transmitted from the TX, and superimposes the information to be transmitted to the TX on the electromagnetic wave by load modulation of the electromagnetic wave, thereby communicating with the TX. That is, communication performed by the communication unit 206 is performed by superimposing information on the power transmitted from the power transmission coil 305 of the TX. The communication unit 206 may perform out-of-band communication with the TX.

[0047] The display unit 207 presents information to the user by any method such as visual, audio, or tactile methods. For example, the display unit 207 notifies the user of the status of the RX, or the status of the wireless power transmission system including the TX and the RX as Figure 1 shown. The display unit 207 includes, for example, a liquid crystal display, an LED, a speaker, a vibration generating circuit, or other notification devices. The operation unit 208 has a function of accepting operations on the RX from the user. The operation unit 208 includes, for example, an audio input device (such as buttons, a keyboard, and a microphone), a motion detection device (such as an acceleration sensor and a gyro sensor), or other input devices. A device in which the display unit 207 and the operation unit 208 are integrated (such as a touch panel) can be used. As described above, the memory 209 stores various information. The memory 209 can store information obtained by functional units different from the control unit 201. The timer 210 measures time using, for example, an up-counter timer for measuring the time elapsed since the timer was started or a down-counter timer for counting down from a set time.

[0048] Figure 3 FIG. is a diagram showing a structural example of the TX according to the present embodiment. In the example, the TX includes a control unit 301, a power supply unit 302, a power transmission unit 303, a detection unit 304, a power transmission coil 305, a communication unit 306, a display unit 307, an operation unit 308, a memory 309, and a timer 310.

[0049] The control unit 301 performs overall control of the TX by executing, for example, a control program stored in the memory 309. In the example, the control unit 301 performs device authentication in the TX and control required for power transmission. The control unit 301 can perform control for executing applications other than wireless power transmission. The control unit 301 includes, for example, one or more processors such as a central processing unit (CPU) and a microprocessing unit (MPU). The control unit 301 can include hardware dedicated to specific processing (such as an application specific integrated circuit (ASIC)) and an array circuit (such as a field programmable gate array (FPGA)) compiled to execute a predetermined process. The control unit 301 causes the memory 309 to store information to be stored while various processes are being executed. In addition, the control unit 301 can use the timer 310 to measure time.

[0050] The power supply unit 302 supplies power required for control, power transmission, and communication to the entire TX. The power supply unit 302 is, for example, a commercial power supply or a battery.

[0051] The power transmission unit 303 converts the DC or AC power input from the power supply unit 302 into AC frequency power having a frequency band used for wireless power transmission, and inputs the AC frequency power into the power transmission coil 305, thereby generating electromagnetic waves to be received by the RX. The frequency of the AC power generated by the power transmission unit 303 is several hundred kHz (for example, 110 kHz to 205 kHz). According to an instruction from the control unit 301, the power transmission unit 303 inputs the AC frequency power into the power transmission coil 305 so that electromagnetic waves for power transmission to the RX are output from the power transmission coil 305. The power transmission unit 303 adjusts the voltage (transmission voltage) or current (transmission current) input to the power transmission coil 305, thereby controlling the intensity of the electromagnetic waves to be output. When the transmission voltage or transmission current increases, the intensity of the electromagnetic waves increases. When the transmission voltage or transmission current decreases, the intensity of the electromagnetic waves decreases. According to an instruction from the control unit 301, the power transmission unit 303 controls the output of the AC frequency power so that power transmission from the power transmission coil 305 starts or stops.

[0052] The detection unit 304 detects whether there is an object in the range 104 according to the WPC standard. For example, the detection unit 304 detects the voltage value or current value of the power transmission coil 305 when the power transmission unit 303 transmits an analog Ping of the WPC standard via the power transmission coil 305. Then, if the voltage drops below a predetermined voltage value or the current value exceeds the predetermined current value, the detection unit 304 may determine that there is an object in the range 104. Regarding the determination of whether the object is the RX or any other foreign object, if a predetermined response is received for the digital Ping subsequently transmitted by the communication unit 306 using in-band communication, it is determined that the object is the RX.

[0053] The communication unit 306 performs control communication with the RX according to the WPC standard as described above using in-band communication. The communication unit 306 modulates the electromagnetic waves output from the power transmission coil 305 and transmits information to the RX. The communication unit 306 demodulates the electromagnetic waves output from the power transmission coil 305 and modulated in the RX to obtain the information transmitted by the RX. That is, in the communication performed by the communication unit 306, information is superimposed on the power transmitted from the power transmission coil 305. The communication unit 306 can perform out-of-band communication with the RX.

[0054] The display unit 307 presents information to the user by any method such as visual, audio, or tactile methods. For example, the display unit 307 notifies the user of the state indicating the TX or as Figure 1Information on the state of the wireless power transmission system including TX and RX. The display unit 307 includes, for example, a liquid crystal display, an LED, a speaker, a vibration generating circuit, or other notification devices. The operation unit 308 has a function of accepting an operation on the TX from the user. The operation unit 308 includes, for example, an audio input device (such as buttons, a keyboard, and a microphone), a motion detection device (such as an acceleration sensor and a gyro sensor), or other input devices. A device in which the display unit 307 and the operation unit 308 are integrated (such as a touch panel) can be used. As described above, the memory 309 stores various information. The memory 309 can store information obtained by a functional unit different from the control unit 301. The timer 310 measures time, for example, using an up-counter timer for measuring the time elapsed since the timer was started or a down-counter timer for counting down from a set time.

[0055] (Flow of the process executed by the power transmission device)

[0056] Next, an example of the flow of the process executed by the TX will be described. Figure 4 An example of the flow of the process executed by the TX is shown. This process can be implemented, for example, by the control unit 301 of the TX executing a program read from the memory 309. At least a part of the following processes can be implemented in hardware. The hardware in this case can be implemented, for example, by automatically generating a dedicated circuit including a gate array circuit (such as an FPGA) from a program for implementing the processing steps using a predetermined compiler. This process can be executed in response to turning on the TX, in response to an instruction from the user of the TX to start the wireless charging application, or in response to the TX being connected to a commercial power supply and receiving power therefrom. Alternatively, other triggers can be used to start this process.

[0057] In this process, the TX first executes the processes defined as the selection phase and the Ping phase in the WPC standard and waits for the RX to be placed (S401). In these phases, the TX repeatedly transmits the analog Ping of the WPC standard intermittently and detects an object present in the power transmission range. Then, if an object is detected in the power transmission range, the TX transmits the digital Ping of the WPC standard. If a predetermined response to the digital Ping is received, the TX determines that the detected object is the RX and the RX is placed on the charging stand 103.

[0058] If it is detected in S401 that the RX is placed, the TX obtains identification information and capability information from the RX using communication in the configuration phase defined in the WPC standard (S402). Here, the identification information of the RX includes a manufacturer code and a basic device ID. The capability information of the RX includes an information element capable of specifying the version of the corresponding WPC standard, a maximum power value (which is a value specifying the maximum power that the RX can supply to a load), and information indicating whether the RX has a negotiation function of the WPC standard. These are merely examples, and the identification information and capability information of the RX may be replaced by other information or may include other information in addition to the above information. For example, the identification information may be any other identification information capable of identifying an individual RX (such as a wireless power ID, etc.). The TX may obtain the identification information and capability information of the RX by a method other than communication in the configuration phase of the WPC standard.

[0059] Subsequently, the TX uses communication in the negotiation phase defined in the WPC standard to negotiate with the RX to determine the value of GP (S403). The process performed in S403 is not limited to communication in the negotiation phase of the WPC standard, and another process for determining GP may be performed. If the TX obtains information indicating that the RX does not correspond to the negotiation phase (e.g., in S402), the TX may determine the value of GP as a small value (e.g., a value predefined in the WPC standard) without performing communication in the negotiation phase.

[0060] After determining GP, the TX performs calibration based on the determined GP (S404). Calibration is a process for calibrating the correlation between the power transmitted by the TX to the RX, the value of the transmission power output (which is a value measured by the TX in its own device), and the value of the received power (which is a value measured by the RX in its own device). For example, the TX estimates the power loss that can be determined as the difference between the value of the transmission power output and the value of the received power based on the value of the received power received from the RX and used as a reference value for calibration and the value of the transmission power output set when obtaining the received power used as the reference value. In the calibration process, when the state of the RX is two different states, the transmission power of the TX and the received power of the RX can be obtained. Then, using these two sets of transmission power and received power, parameters for calibrating the received power or transmission power during actual wireless power transmission can be calculated. These parameters refer to the slope value and intercept value when the correlation between the transmission power and the received power is graphically represented by a linear function. The combination used to calculate these parameters is not limited to the set of transmission power and received power, and may be a set of transmission power and power loss, or may be a set of received power and power loss.

[0061] As Figure 9AAs shown, communication is performed during the calibration phase of the WPC standard during calibration. In this process, as Figure 9A shown, first, the RX transmits information on the received power in the light load state, which is used as the first calibration reference value (hereinafter referred to as "first calibration reference value information") to the TX (F901). Here, for example, the received power (mode 1), which is a message defined in the WPC standard, is used to transmit and receive the first calibration reference value information. However, other messages can be used. The TX determines whether to accept the first calibration reference value information based on its own power transmission state. If the TX accepts the first calibration reference value information, the TX transmits an affirmative acknowledgment (ACK) to the RX, and if the TX does not accept the first calibration reference value information, the TX transmits a negative acknowledgment (NAK) to the RX (F902). Here, for example, if the TX determines that its own power transmission state is stable, the TX accepts the notification, and if the TX determines that its own power transmission state is unstable, the TX does not accept the notification. The calibration reference value information accepted by the TX can be referred to as valid calibration reference value information. If the RX receives a NAK from the TX, the RX transmits the first calibration reference value information again. On the other hand, if the RX receives an ACK from the TX, the RX transmits information on the received power in the load-connected state, which is used as the second calibration reference value (hereinafter referred to as "second calibration reference value information") to the TX (F903). Here, for example, the received power (mode 2), which is a message defined in the WPC standard, is used to transmit and receive the second calibration reference value information. However, other messages can be used. The TX determines whether to accept the second calibration reference value information based on its own power transmission state. Similar to F902, if the TX accepts the second calibration reference value information, the TX transmits an ACK to the RX, and if the TX does not accept the second calibration reference value information, the TX transmits a NAK to the RX (F904). If the RX receives a NAK from the TX, the RX transmits the second calibration reference value information again. When transmitting an ACK to the RX, the TX specifies the corresponding power loss when using these two reference values based on the received power included in the first calibration reference value information and the second calibration reference value information. Then, the TX estimates the power loss when receiving the received power of a value different from these two reference values, for example, using linear interpolation based on the specified two power loss values. If the TX is unable to transmit an ACK as a response to the second calibration reference value information within a predetermined time after the negotiation phase (S403) is completed, the TX can determine that the calibration has failed and can stop power transmission. Calibration can be performed by methods other than the WPC standard method.

[0062] After calibration is completed, the TX starts power transmission (S405). Power transmission is performed through the process in the power transfer phase of the WPC standard. However, power transmission is not limited to this, and can be performed by methods other than the WPC standard method.

[0063] Subsequently, communication for device authentication is performed between TX and RX (S406). Here, reference will be made to Figure 9B to describe the communication for device authentication performed between RX and TX. Assume that: the device authentication in this embodiment is a challenge-response device authentication using an electronic certificate, and RX authenticates TX. TX can authenticate RX, or both TX and RX can authenticate each other's devices. RX operates as the initiator that transmits a challenge text to TX, and TX operates as the responder that encrypts the challenge text received from RX and transmits the encrypted challenge text to RX. First, RX transmits a GET_DIGESTS message (F911) to TX. GET_DIGESTS is a message that requests information related to the electronic certificate possessed by the message recipient (TX). In response to GET_DIGESTS, TX transmits DIGESTS (digest) (F912) to RX. DIGESTS is a message that includes information related to the electronic certificate possessed by the message transmitter (TX). Subsequently, RX transmits a GET_CERTIFICATE message (F913) that requests detailed information related to the electronic certificate to TX. In response to GET_CERTIFICATE from RX, TX transmits CERTIFICATE (certificate) (F914) to RX. Then, RX transmits a CHALLENGE (challenge) message (F915) that includes a challenge text to TX, and TX transmits CHALLENGE_AUTH obtained by encrypting the challenge text received from RX (F916) to RX. When RX verifies the correctness of the CHALLENGE_AUTH received from TX, it determines that the device authentication is successful, and when it cannot verify the correctness, it determines that the device authentication fails. When this determination is completed, the device authentication process ends.

[0064] If the initiator (RX) receives a message indicating that the other device (TX) does not support the communication for device authentication, the initiator (RX) determines that the other device does not support device authentication. If the initiator (RX) does not receive a response during the communication, the initiator (RX) can, for example, retry by resending the message for obtaining the response, or can determine that the other device (TX) does not support device authentication. RX can be configured not to perform the communication for device authentication with a TX that does not support device authentication and not to determine the result of device authentication as successful. Here, it is assumed that the device authentication is successful in S406.

[0065] Returning to the reference Figure 4, TX, together with RX, re-determines the value of GP through communication in the negotiation phase defined in the WPC standard (S407). Here, since the device authentication in S406 is successful, the value determined for GP is a value greater than 5W (for example, 15W). After re-determining GP, TX repeatedly executes power transmission control processing (S408). If the end of power transmission in the WPC standard is received from RX, TX ends the processing executed in any processing stage according to the WPC standard, stops power transmission, and then returns to the selection stage in S401. In the case where the full charge state is reached, the end of power transmission is also transmitted from RX. Therefore, TX returns to the selection stage in S401.

[0066] Reference will be made Figure 5 to an example of the flow of the power transmission control processing executed by TX in S408. This processing can be implemented, for example, by the control unit 301 of TX executing a program read from the memory 309. At least a part of the following processing can be implemented in hardware. The hardware in this case can be implemented, for example, by automatically generating a dedicated circuit including a gate array circuit (such as an FPGA, etc.) from a program for implementing the processing steps using a predetermined compiler.

[0067] Using the start of the processing as a trigger, TX starts a timer until the calculation of the estimated value of power loss is completed (S501). The start of this processing can be used as a trigger, or in other words, using the transmission of ACK for a specific request (hereinafter referred to as "SRQ / en") defined in the WPC standard and indicating the completion of communication in the negotiation phase as a trigger to start the timer. However, the present invention is not limited thereto, and for example, the completion of the calculation of the estimated value of power loss or the transmission of ACK for the received calibration reference value information can be used as a trigger to start the timer. Optionally, the timer can be started at the timing of receiving SRQ / en. After starting the timer, TX determines whether a power transmission output change indication is received from RX (S502). Here, the power transmission output change indication is made by including a control error value, which is a value representing the amount of change in voltage, in the control error message of the WPC standard. In the control error value, a positive value is stored if the power transmission output is to be increased, a negative value is stored if the power transmission output is to be decreased, and 0 is stored if the power transmission output is not to be changed. If a power transmission output change indication is received (Yes in S502), TX changes the power transmission output based on the indicated amount of change (S503), and the processing proceeds to S504. On the other hand, if a power transmission output change indication is not received (No in S502), TX proceeds to S504 without performing any operation.

[0068] In S504, the TX determines whether it has received received power information from the RX. Here, the received power information is information including the received power actually received in the RX at that time point. The received power (mode 0) message defined in the WPC standard is used to transmit and receive this received power information. However, the present invention is not limited thereto. If the received power information is received (Yes in S504), the TX transmits an ACK (S505) and proceeds to S506. On the other hand, if the received power information is not received (No in S504), the TX proceeds to S506 without performing any operation.

[0069] In S506, the TX determines whether it has received enhanced calibration reference value information from the RX. Here, the enhanced calibration reference value information is information including the received power in the load connection state that is used as a reference value for additional calibration for calculating an estimated value of power loss. If the enhanced calibration reference value information is received (Yes in S506), the TX proceeds to S507, and if the enhanced calibration reference value information is not received (No in S506), the TX proceeds to S511. In S507, the TX determines whether to accept the enhanced calibration reference value information received in S506. Here, the TX can determine whether to accept the enhanced calibration reference value information based on whether its own power transmission state is stable. However, the present invention is not limited thereto. For example, if the power loss of the received power represented by the enhanced calibration reference value information deviates from the estimated value of the calculated power loss by more than a predetermined value, the TX can determine not to accept the enhanced calibration reference value information.

[0070] If the TX accepts the enhanced calibration reference value information (Yes in S507), the TX calculates an estimated value of the power loss based on the received power indicated by the enhanced calibration reference value information (S508), and transmits an ACK to the RX (S509). The calculation of the estimated value of the power loss and the transmission of the ACK may be performed in the reverse order, or may be performed simultaneously (the processing time periods of both may at least partially overlap). Then, the TX resets the timer (S513), and ends the processing. The estimated value of the power loss is estimated, for example, based on both: the first power loss at the first received power indicated by the enhanced calibration reference value information received in S506, and the second power loss estimated based on the second received power indicated by the previous calibration reference value information. For example, based on the value L1 of the first power loss corresponding to the first received power P1 and the value L2 of the second power loss corresponding to the second received power P2, the value of the power loss corresponding to the received power P between P1 and P2 is calculated as (L2 - L1) / (P2 - P1)×(P - P1)+L1. However, the method for estimating the power loss is not limited to linear interpolation. For example, based on at least one calibration reference value information received during and after the calibration phase, statistical analysis such as linear approximation and polynomial approximation may be used to calculate the estimated value of the power loss. The estimation method may be selected from these estimation methods according to the number of available calibration reference value information and the calculation resources of the TX. Therefore, in the case of sufficient calculation resources, a highly accurate estimated value can be calculated by performing statistical analysis using a larger number of calibration reference value information. In the case of insufficient calculation resources, the calculation time required for the calculation can be reduced by performing a simple estimation such as linear interpolation.

[0071] On the other hand, if the TX does not accept the enhanced calibration reference value information (being "No" in S507), the TX transmits a NAK to the RX (S510) and determines whether a timeout has occurred (S511). The TX can determine whether a timeout has occurred based on whether the calculation of the estimated value of power loss is completed within a predetermined time after starting the timer in S501. That is, if a predetermined time has elapsed without receiving the enhanced calibration reference value information from the RX, or if a predetermined time has elapsed without transmitting an ACK for the enhanced calibration reference value information, the TX can determine that a timeout has occurred. Instead of or in addition to measuring time with a timer, the TX can determine whether the number of receptions of the power transmission output change indication received from the RX or the number of receptions of predetermined information different from the calibration reference value information (such as the received power information received from the RX, etc.) has become greater than or equal to a predetermined number. For example, in S501, when starting the timer, or instead of starting the timer, the TX can reset the number of receptions of the indication or information to 0, increment the number of receptions each time the TX receives the indication or information, and determine in S511 whether the number has reached the predetermined number. Instead of or in addition to measuring time with a timer, the TX can determine whether the number of transmissions of NAKs for the received enhanced calibration reference value information has become greater than or equal to a predetermined number. Also in this case, the TX can reset the number of transmissions of NAKs to 0 in S501, increment the number of transmissions each time the TX transmits a NAK, and determine in S511 whether the number has reached the predetermined number. If it is determined that a timeout has occurred (being "Yes" in S511), the TX performs a timeout process (S512). When the timeout process is completed, the TX resets the timer (S513) and ends this process. The timeout process in S512 will be described later. On the other hand, if it is determined that no timeout has occurred (being "No" in S511), the TX returns the process to S502.

[0072] As described above, the TX repeatedly executes Figure 5The processing shown. By repeatedly executing this processing and sequentially updating the estimated value of the power loss using the enhanced calibration reference value information, it is possible to prevent a decrease in the accuracy of foreign object detection by performing foreign object detection based on the latest estimated value of the power loss. As a result, it is possible to prevent charging suspension due to misdetection of a foreign object and temperature increase caused by failure to detect an existing foreign object, thereby improving convenience. If the timer is reset in S513, the timer in S501 can be started at that time point. That is, the timer can be reset and restarted at the same timing. If valid calibration reference value information is obtained, the timer can be reset, for example, at a predetermined timing associated with the timing of obtaining the calibration reference value information (such as the timing of obtaining the calibration reference value information, the timing of calculating the estimated value of the power loss, and the timing of transmitting an ACK, etc.). During the timeout processing, the timer can be reset at a predetermined timing such as the reception timing of the received power information indicating that the received power has dropped to the target value, the reception timing of valid enhanced calibration reference value information, and the transmission timing of an ACK for this information.

[0073] Next, reference will be made to Figure 6A and Figure 6B to describe the flow of the timeout processing executed in Figure 5 S512. This processing can be implemented, for example, by the control unit 301 of the TX executing a program read from the memory 309. At least a part of the following processing can be implemented in hardware. In this case, the hardware can be implemented, for example, by automatically generating a dedicated circuit including a gate array circuit (such as an FPGA, etc.) from a program for implementing the processing steps using a predetermined compiler.

[0074] After starting the process, the TX determines whether it has received a power transmission output change indication from the RX (S601). If it has received the power transmission output change indication ("Yes" in S601), the TX advances the process to S602, and if it has not received the power transmission output change indication ("No" in S601), the TX advances the process to S605. In S602, the TX determines whether the power transmission output change indication is an indication to increase the power transmission output, or in other words, whether a positive value is included in the control error value in the control error message, for example. If it is determined that the power transmission output change indication indicates an increase in the power transmission output ("Yes" in S602), the TX does not change the power transmission output (S603) and advances the process to S605. That is, in a case where, for example, a certain period of time has elapsed without obtaining any new calibration reference values after updating the calibration reference value and it is determined that a timeout has occurred, the TX is configured not to comply with the power transmission output change indication to increase the power transmission output. In a case where the accuracy of foreign object detection decreases as a result of the calibration reference value information lacking accuracy after a long time has elapsed since the update of the calibration reference value, although there is a foreign object, the TX may determine that there is no foreign object. Therefore, it is possible to prevent temperature rises and the like by configuring the TX not to increase the power transmission output in an environment where there is a foreign object but there is a possibility of not detecting the presence of the foreign object. On the other hand, if it is determined that the power transmission output change indication is not an indication to increase the power transmission output ("No" in S602), the TX changes the power transmission output based on the indicated change amount (S604) and advances the process to S605.

[0075] In S605, the TX determines whether it has received received power information from the RX (S605). If it has received the received power information ("Yes" in S605), the TX advances the process to S606, and if it has not received the received power information ("No" in S605), the TX advances the process to S609. In S606, the TX determines whether the received power has decreased to a target value based on the received received power information. Here, the target value may be set to the received power within the range of the GP before re-executing the negotiation, but is not limited thereto. For example, the target value may be set to the received power indicated by the last accepted (ACK has been transmitted) calibration reference value information, the maximum received power among the received power indicated by the past accepted calibration reference value information.

[0076] If it is determined that the received power has decreased to the target value (Yes in S606), then the TX transmits an ACK (S607), and this process ends. On the other hand, if it is determined that the received power has not decreased to the target value (No in S606), then the TX transmits a NAK (S608), and the process proceeds to S609. In S609, the TX determines whether enhanced calibration reference value information has been received. If it is determined that the enhanced calibration reference value information has been received (Yes in S609), then the TX makes the process proceed to S610, and if it is determined that the enhanced calibration reference value information has not been received (No in S609), then the TX returns the process to S601. Similar to the cases of the first calibration reference value information and the second calibration reference value information, the TX determines whether to accept the enhanced calibration reference value information (S610). Then, if the TX accepts the enhanced calibration reference value information (Yes in S610), then the TX transmits an ACK (S611), calculates an estimated value of the power loss based on the enhanced calibration reference value information (S613), and ends this process. On the other hand, if the TX does not accept the enhanced calibration reference value information (No in S610), then the TX transmits a NAK (S612), and returns the process to S601. After this process is completed, the TX makes the process proceed to S513, and then repeats the Figure 5 processing shown.

[0077] (Flow of the process executed by the power receiving device)

[0078] Next, an example of the flow of the process executed by the RX will be described. Figure 7 An example of the flow of the process executed by the RX is shown. This process can be implemented, for example, by the control unit 201 of the RX executing a program read from the memory 209. At least a part of the following processes can be implemented in hardware. In this case, the hardware can be implemented, for example, by automatically generating a dedicated circuit including a gate array circuit (such as an FPGA, etc.) from a program for implementing the processing steps using a predetermined compiler. This process can be started in response to turning on the RX as a result of using the power supplied from the battery 202 or the TX, or in response to an instruction from the user of the RX to start the wireless charging application. Optionally, other triggers can be used to start this process.

[0079] After starting the process, the RX performs the processes defined as the selection phase and the Ping phase in the WPC standard, and waits for its own device to be placed on the TX (S701). The RX detects that its own device is placed on the TX, for example, by detecting a digital Ping from the TX. If it is determined that its own device is placed on the TX, the RX transmits identification information and capability information to the TX using the communication in the configuration phase defined in the WPC standard (S702). After the RX transmits the identification information and the capability information, the RX determines the GP using the communication in the negotiation phase defined in the WPC standard (S703). Here, since the communication for device authentication is not performed, the RX determines to perform negotiation so that the GP is 5W. Here, the RX makes a reference based on the determined GP Figure 9A to the communication in the calibration phase of the WPC standard described above. When the calibration is completed, the RX starts receiving power using the communication in the power transfer phase defined in the WPC standard (S705). After starting to receive power, the RX makes a reference Figure 9B to the communication for device authentication described above (S706). Assume that the device authentication is successful. After that, the RX performs negotiation and re-determines the value of the GP together with the TX (S707). Since the device authentication is successful, in S707, the RX determines a value larger than 5W (for example, 15W) as the GP. After re-determining the GP, the RX repeatedly executes the power reception control process (S708). If an error occurs or if the full charge state is reached, the RX transmits the end of power transfer of the WPC standard. Accordingly, the power transmission from the TX is stopped, and a series of processes for wireless charging ends.

[0080] Next, a reference will be made Figure 8 to an example of the flow of the power reception control process executed in S708. This process can be implemented, for example, by a program read from the memory 209 by the control unit 201 of the RX. At least a part of the following processes can be implemented in hardware. The hardware in this case can be implemented, for example, by automatically generating a dedicated circuit including a gate array circuit (such as an FPGA) from a program for implementing the processing steps using a predetermined compiler.

[0081] After starting the process, the RX determines whether the received power is less than the GP (S801). If it is determined that the received power is less than the GP (Yes in S801), the RX increases the power consumption (S802), transmits a power transmission output change instruction instructing an increase in the power transmission output to the TX (S803), and advances the process to S805. On the other hand, if it is determined that the received power is greater than or equal to the GP (No in S801), the RX does not change the power consumption, transmits a power transmission output change instruction instructing to maintain the power transmission output to the TX (S804), and advances the process to S805.

[0082] In S805, the RX determines whether the transmission timing of the enhanced calibration reference value information has been reached. Here, the determination regarding whether the transmission timing of the enhanced calibration reference value information has been reached can be made based on whether a predetermined time has elapsed after the negotiation is completed. However, the present invention is not limited thereto. For example, the RX can make the determination in S805 based on whether the time elapsed after the TX finishes calculating the estimated value of the power loss and the RX receives the ACK for the calibration reference value information reaches a predetermined time. Alternatively, the RX can use an index other than the elapsed time to make the determination in S805. For example, the RX can determine whether the transmission timing of the enhanced calibration reference value information has been reached based on whether the difference between the received power at the time of negotiation completion and the current received power is greater than or equal to a threshold value. The RX can use the difference between the received power indicated by the calibration reference value information for which the ACK was most recently received and the current received power to determine whether the transmission timing of the enhanced calibration reference value information has been reached. This enables the RX to reliably transmit the enhanced calibration reference value information to the TX in the case where there is a certain amount of change in the received power, or in other words, in the case where it is assumed that there is a large error in the estimated value of the power loss of the TX.

[0083] If it is determined that the transmission timing of the enhanced calibration reference value information has been reached (Yes in S805), the RX transmits the enhanced calibration reference value information including the current received power (S806), and determines whether a NAK is received from the TX (S807). If it is determined that a NAK for the transmitted enhanced calibration reference value information is received from the TX (Yes in S807), the RX re-transmits the enhanced calibration reference value information (S806). If a NAK is received, the RX can use the display unit 207 to perform a display for prompting the user to, for example, re-place the RX. Thus, in the case where the power transmission in the TX becomes unstable due to, for example, a positional shift of the TX, the predetermined process for starting charging can be re-executed, thereby restarting stable charging. On the other hand, if an ACK is received for the enhanced calibration reference value information (No in S807), the RX ends this process without performing any operation.

[0084] On the other hand, if it is determined that the transmission timing of the enhanced calibration reference value information has not been reached (No in S805), the RX transmits the received power information to the TX at a predetermined time interval, for example (S808), and determines whether an NAK is received from the TX (S809). If an NAK for the transmitted received power information is received from the TX (Yes in S809), the RX reduces power consumption (S810), transmits a transmission output change instruction indicating a reduction in the transmission output of the TX to the TX (S811), and ends this process. On the other hand, if an ACK for the received power information is received from the TX (No in S809), the RX ends this process without performing any operation.

[0085] As a result of the RX periodically transmitting the enhanced calibration reference value information during the increasing or decreasing phase of the transmission output, a significant deviation between the received power of the calibration reference value and the actual received power can be prevented. For example, when the transmission output is increasing, if the calibration reference value information is notified from the RX to the TX within a certain time period, the TX can obtain a new calibration reference value that is higher in received power than the previously obtained calibration reference value and does not deviate significantly from the received power of these calibration reference values. Similarly, when the transmission output is decreasing, if the calibration reference value information is notified from the RX to the TX within a certain time period, the TX can obtain a new calibration reference value that is lower in received power than the previously obtained calibration reference value and does not deviate significantly from the received power of these calibration reference values. In addition, by using such a new calibration reference value, the TX can accurately estimate the power loss compared to the case where no such calibration reference value is available. Generally, when the difference between the received power of the calibration reference value and the actual received power increases, the estimation error of the expected power loss also increases. In this regard, by notifying the calibration reference value information corresponding to the current received power from the RX to the TX within a certain time period, the TX can obtain the received power of the calibration reference value within a range where the received power does not deviate from the existing calibration reference value by more than a certain level. As a result, for example, the TX can fully obtain the calibration reference values for a wide range of received powers, so that the RX will not receive power that significantly deviates from the received power corresponding to the calibration reference value. This enables accurate estimation of the power loss for any received power, thereby preventing misdetection of foreign objects and failure to detect existing foreign objects. If the TX cannot obtain the enhanced calibration reference value information within a certain time period during the increasing or decreasing phase of the transmission output, there is a possibility that the current received power significantly deviates from the received power of the calibration reference value. For this reason, timeout judgment can be used, and if a timeout occurs, the TX can be configured not to increase (or decrease) the transmission output, so that power transmission / reception using power that may reduce the accuracy of foreign object detection can be prevented.

[0086] The above-described processing operation associated with timeout can be performed only when the power transmission output increases (or decreases) to such an extent that the received power in RX exceeds the received power of the existing calibration reference value. The reason is that if the received power is within the range of the received power of the existing calibration reference value, an accurate estimation of power loss can be made without having to obtain an additional calibration reference value. For example, the TX can set a validity period for each calibration reference value. In addition, the TX can discard the reference value that has exceeded the set validity period and perform the above processing. For example, if the power transmission output is to be increased / decreased such that the received power changes beyond the range of the received power specified by the reference value held in the TX, the TX can perform the above-described processing operation associated with timeout.

[0087] (Flow of the processing executed in the system)

[0088] Several scenarios will be assumed to illustrate the operation sequence of the TX and RX performing the above processing. Assume that in the initial state, the RX is not placed on the TX, and the TX has the power transmission capacity sufficient to perform the power transmission of the GP requested from the RX.

[0089] <Processing Example 1>

[0090] First, reference will be made to Figure 10A and Figure 10B to illustrate the first processing example. In this processing example, the GP is determined to be 5W in the initial negotiation, and power transmission starts. Then, after the start of power transmission, the device authentication is successful, and the GP is re-determined to be 15W through re-executing the negotiation. Using the completion of the negotiation as a trigger, or in other words, using the transmission of the ACK for SRQ / en as a trigger, the TX starts a timer. In addition, assume that during the period when the received power in the RX changes from 5W to 15W, the TX can neither receive the enhanced calibration reference value information nor transmit the ACK within a predetermined time. At this time, the TX in this processing example reduces the power transmission output with the GP range (5W) before device authentication as the target value.

[0091] The TX uses an analog Ping to wait for an object to be placed (S401, F1001). As a result of the RX being placed (F1002), there is a change in the analog Ping (F1003), whereby the TX detects that an object has been placed (F1004). Based on a subsequent digital Ping, the RX detects that its own device has been placed on the TX (S701, F1005, F1006). Based on the response to the digital Ping, the TX detects that the object placed on it is the RX. Subsequently, using the communication in the configuration phase, the TX obtains identification information and capability information from the RX (S402, S702, F1007). Then, the TX and the RX perform communication in the negotiation phase (S403, S703, F1008). At this time, the device authentication is not successful, so GP is determined to be 5W in this negotiation.

[0092] Subsequently, the TX and the RX start communication in the calibration phase (S404, S704). In the communication in the calibration phase, the TX receives from the RX first calibration reference value information indicating that the received power is 500 mW (F1009). Then, for example, as a result of determining that the power transmission state of the TX itself is stable, the TX determines to accept the first calibration reference value information and transmits an ACK (F1010). Next, the TX receives from the RX a power transmission output change instruction indicating an increase in the power transmission output (F1011), and increases the power transmission output according to this instruction (F1012). After that, the TX receives from the RX second calibration reference value information indicating that the received power is 5W (F1013). For example, as a result of determining that the power transmission state of the TX itself is stable, the TX determines to accept the second calibration reference value information and transmits an ACK (F1015). In addition, the TX calculates an estimated value of the power loss based on the first calibration reference value information and the second calibration reference value information (F1014). By transmitting an ACK in F1015, the power transmission phase starts (S405, S705). Subsequently, communication for device authentication is performed (S406, S706, F1016). It is assumed that the device authentication is successful. If the device authentication is successful, the TX and the RX re - execute the communication in the negotiation phase and re - determine GP (S407, S707, F1017). Here, it is assumed that GP is re - determined to be 15W. After re - determining GP, the TX and the RX respectively start power transmission control processing and power reception control processing (S408, S708).

[0093] After starting the power transmission control process, TX starts a timer until the calculation of the estimated value of power loss is completed (S501, F1018). If a power transmission output change instruction indicating an increase in power transmission output is received from RX, TX increases the power transmission output according to this instruction (S503, S802, S803, F1019, F1020). Subsequently, TX receives power reception information indicating that the received power is 15 W from RX (S808, F1021), and transmits an ACK for this power reception information (S505, F1022). If a power transmission output change instruction indicating no change in power transmission output is received from RX (S804, F1023), TX complies with this instruction and does not change the power transmission output. After that, TX determines that a timeout has occurred, for example, using the expiration of a predetermined time since starting the timer without receiving enhanced calibration reference value information as a trigger, and starts the timeout process (S512, F1024). After starting the timeout process, if power reception information indicating that the received power is 15 W is received from RX (S808, F1025), TX transmits a NAK to reduce the received power in RX to 5 W as the target value (S608, F1026). RX reduces power consumption (S810, F1027), and transmits a power transmission output change instruction indicating a reduction in power transmission output to TX (S811, F1028). If this power transmission output change instruction is received, TX reduces the power transmission output according to this instruction (S604, F1029). Subsequently, if power reception information indicating that the received power is 10 W is received from RX (S808, F1030), since this received power is higher than 5 W as the target value, TX transmits a NAK to cause RX to continue reducing the received power (S608, F1031). RX reduces power consumption (S810, F1032), and transmits a power transmission output change instruction indicating a reduction in power transmission output to TX (S811, F1033). If this power transmission output change instruction is received, TX reduces the power transmission output according to this instruction (S604, F1034). After that, if power reception information indicating that the received power is 5 W is received (S808, F1035), since this received power is greater than or equal to 5 W as the target value, TX transmits an ACK to RX and continues power transmission at this output (S607, F1036).

[0094] According to the above operations, if it is impossible to calculate the estimated value of power loss after starting fast charging with a relatively high power transmission output, the TX reduces the power transmission output to the output range before the start of fast charging. This enables power transmission and reception using an appropriate power transmission output while assuming the possibility of false detection or detection failure of foreign objects. As a result of the RX periodically transmitting enhanced calibration reference value information during the increasing or decreasing phase of the power transmission output, a significant deviation between the received power of the calibration reference value and the actual received power can be prevented. Therefore, the power loss of the received power that has been increased or decreased can be accurately estimated, thereby preventing false detection of foreign objects and failure to detect existing foreign objects. In the case where the TX cannot obtain the enhanced calibration reference value information within a certain period during the increasing or decreasing phase of the power transmission output, it is determined that a timeout has occurred, and the TX does not increase (or decrease) the power transmission output. This enables prevention of power transmission and reception at a power that may reduce the accuracy of foreign object detection.

[0095] <Processing Example 2>

[0096] Next, reference will be made to Figure 11A and Figure 11B to describe the second processing example. In this processing example, different from Processing Example 1, in the case of a timeout, the TX uses the received power indicated by the valid enhanced calibration reference value information obtained immediately before as the target value to reduce the power transmission output. Here, it is assumed that: after determining the GP, when the received power in the RX changes from 5W to 10W, the TX receives the enhanced calibration reference value information indicating that the received power of the RX is 10W, calculates the estimated value of the power loss, and transmits an ACK. In this case, the TX uses the transmission of the ACK as a trigger to reset the timer and starts the timer again. It is assumed that: afterwards, the received power in the RX changes from 10W to 15W, but the TX cannot receive the enhanced calibration reference value information within the predetermined time. In this case, the TX uses 10W (which is the received power indicated by the last obtained valid enhanced calibration reference value information) as the target value to reduce the power transmission output.

[0097] The processing operations in F1101 to F1120 are the same as the processing operations in F1001 to F1020 in Figure 10A and Figure 10B . Therefore, the description of these processing operations is omitted.

[0098] In F1121, the RX transmits received power information indicating that the received power is 7W to the TX (S808). If this received power information is received, since no timeout has occurred at this time, the TX transmits an ACK (S505, F1122). Since the received power does not reach the GP, the RX then transmits a transmission output change instruction indicating an increase in the transmission output to the TX (S802, S803, F1123). If this transmission output change instruction is received, the TX increases the transmission output according to this instruction (S503, F1124).

[0099] After that, in response to the appearance of the transmission timing of the enhanced calibration reference value information, the RX transmits the enhanced calibration reference value information to the TX (S806, F1125). Here, the enhanced calibration reference value information indicates that the received power in the RX is 10W. If the enhanced calibration reference value information is received, the TX determines to accept this calibration reference value information as a result of judging that its own transmission state is stable, calculates an estimated value of the power loss (S508, F1126), and transmits an ACK (S509, F1127).

[0100] After transmitting the ACK, the TX resets the timer and starts the timer again (S513, S501, F1128, F1129). After that, the RX transmits received power information indicating that the received power is 13W to the TX (S808, F1130). If this received power information is received before the timer expires, the TX transmits an ACK (S505, F1131). After that, the TX uses the fact that a predetermined time has elapsed without receiving the enhanced calibration reference value information since the timer was started in F1129 as a trigger, judges that a timeout has occurred, and starts timeout processing (S512, F1132).

[0101] Since the received power does not reach GP, the RX then transmits a transmission output change indication (S802, S803, F1133) to the TX indicating an increase in the transmission output. The TX receives this transmission output change indication, but does not comply with the indication due to a timeout and does not change the transmission output (S603, F1134). Then, the RX transmits received power information indicating that the received power is 13 W to the TX (S808, F1135). If this received power information is received, since the timeout process has started, the TX transmits a NAK to the RX so that the RX reduces the received power to the target value of 10 W (S608, F1136). If the NAK is received, the RX reduces the power consumption (S810, F1137) and transmits a transmission output change indication to the TX indicating a reduction in the transmission output (S811, F1138). If the transmission output change indication is received, the TX reduces the transmission output according to the indication (S604, F1139). Then, the RX transmits received power information indicating that as a result of the reduction in the transmission output, the received power has been reduced to 10 W to the TX (S808, F1140). If the received power information indicating that the received power is 10 W is received, since the received power has been reduced to 10 W or less, which is the target value, the TX transmits an ACK (S607, F1041). Then, the TX continues the power transmission while maintaining the transmission output.

[0102] According to the above operations, if the estimated value of the power loss cannot be calculated after starting fast charging with a relatively high transmission output, the TX reduces the transmission output so that the received power at which the estimated value of the power loss has been calculated can be obtained. This enables the continuation of power transmission and reception using an appropriate transmission output while assuming the possibility of false detection or detection failure of foreign objects. As a result of the RX periodically transmitting enhanced calibration reference value information during the increase or decrease phase of the transmission output, a significant deviation between the received power of the calibration reference value and the actual received power can be prevented. Therefore, the power loss of the received power that has been increased or decreased can be accurately estimated, thereby preventing false detection of foreign objects and failure to detect existing foreign objects. If the TX cannot obtain the enhanced calibration reference value information within a certain period during the increase or decrease phase of the transmission output, it is determined that a timeout has occurred, and the TX does not increase (or decrease) the transmission output. This enables the prevention of power transmission and reception that may reduce the accuracy of foreign object detection.

[0103] TX can start the above timer at a timing before re - performing device authentication and negotiation. For example, TX can use the completion of calibration resulting from receiving the second calibration reference value information as a trigger, or in other words, use the transmission of an ACK for the second calibration reference value information as a trigger to start the timer. At this time, in the case where calibration is completed using a received power smaller than 5W (which is the GP determined by the power - receiving device with unsuccessful device authentication), TX can start the timer. Then, if TX cannot receive the enhanced calibration reference value information (for example, indicating that the received power is 5W, etc.) within a predetermined time, TX uses the received power of 3W represented by the second calibration reference value information as the target value to reduce the power transmission output. By reducing the power transmission output in this way to the output used at the completion of calibration before the start of fast charging, power transmission and power reception can continue with an appropriate output in a state where the power transmission output is small and thus error variations tend to be large.

[0104] TX can use the change amount of the received power becoming greater than or equal to a threshold value as a trigger to start the above timer. That is to say, TX can be configured not to perform Figure 5 Or Figure 6A And Figure 6BThe processing operations associated with timeout as shown. For example, TX can use the received received power information or calibration reference value information as follows as a trigger, or use the transmission of a response to the received power information or calibration reference value information as a trigger to start a timer. The received power information or calibration reference value information indicates that the change in received power relative to the received power immediately after calibration completion is greater than or equal to a threshold. TX can use the received received power information or calibration reference value information as follows as a trigger, or use the transmission of a response to the received power information or calibration reference value information as a trigger to start a timer. The received power information or calibration reference value information indicates that the change in received power relative to the received power when obtaining valid enhanced calibration reference value information is greater than or equal to a threshold. TX can use the received received power information or calibration reference value information as follows as a trigger, or use the transmission of a response to the received power information or calibration reference value information as a trigger to start a timer. The received power information or calibration reference value information indicates that the change in received power relative to any received power in the received power represented by the valid calibration reference value information is greater than or equal to a threshold. Therefore, in the case where the change in received power for which the estimated value of power loss has been calculated is not significant, and thus it is considered that the accuracy of foreign object detection is sufficiently ensured, the occurrence of unnecessary timeouts and unnecessary changes in power transmission output can be suppressed. As the threshold for the change in received power, a predetermined fixed value can be used, or a value determined between TX and RX using any communication performed before the start of the power transmission phase can be used. TX can be configured not to perform until the change in received power after obtaining valid enhanced calibration reference value information becomes greater than or equal to the threshold. Figure 5 Or Figure 6A And Figure 6B The processing operations associated with timeout as shown.

[0105] TX can use the change in power transmission output becoming greater than or equal to the threshold as a trigger to start the above-mentioned timer. That is, TX can be configured not to perform until the change in power transmission output becomes greater than or equal to the threshold. Figure 5 Or Figure 6A And Figure 6BThe processing operations associated with timeout as shown. For example, TX can use the change amount of the power transmission output relative to that immediately after calibration completion becoming greater than or equal to a threshold value as a trigger, or use the change amount of the power transmission output relative to the power transmission output when obtaining valid calibration reference value information becoming greater than or equal to a threshold value as a trigger to start a timer. In the example, when the value that increases by 1 when the power transmission output increases according to the above power transmission output change indication and decreases by 1 when the power transmission output decreases according to the power transmission output change indication reaches a predetermined positive value or a predetermined negative value, TX can start the timer. In the case where a value representing the amount by which the power transmission output will change according to the power transmission output change indication is specified, TX can cumulatively add the specified value, and can start the timer when the value reaches a predetermined positive value or a predetermined negative value. TX can monitor its own power transmission output, and can use the change amount reaching a predetermined value as a trigger to start the timer. Therefore, in the case where the change in the power transmission output and the change in the received power after assuming the calculated estimated value of power loss are not significant, the occurrence of unnecessary timeouts and unnecessary changes in the power transmission output can be suppressed. TX can be configured not to execute before the change amount of the power transmission output after obtaining valid enhanced calibration reference value information becomes greater than or equal to a threshold value. Figure 5 Or Figure 6A And Figure 6B The processing operations associated with timeout as shown.

[0106] TX can use receiving enhanced calibration reference value information after calculating the estimated value of power loss as a trigger to start the above-mentioned timer. That is, TX can be configured not to execute before receiving the enhanced calibration reference value information. Figure 5 Or Figure 6A And Figure 6B The processing operations associated with timeout as shown. Therefore, the timeout can be set only when RX intends to calculate the estimated value in the case where the calculated estimated value of power loss can be used for foreign object detection. This makes it possible to suppress the occurrence of unnecessary timeouts and unnecessary changes in the power transmission output.

[0107] When performing power transmission and power reception outside the range of the reference value of the received power, enhanced calibration reference value information can be transmitted. In this case, the expression "outside the range of... reference value" includes both falling below the lower limit value defining the range and exceeding the upper limit value of the range defining the reference value.

[0108] In the case where GP increases as a result of device authentication using an electronic certificate for the power transmission device or device authentication using an electronic certificate for the power reception device, enhanced calibration reference value information can be transmitted.

[0109] For example, in the case of power transmission and reception over a long period of time, the accuracy of foreign object detection processing using the calibration reference value obtained in the calibration stage may be reduced due to the influence of heat generation or the like. For this reason, if a certain amount of time has elapsed after the calibration reference value is obtained, the calibration reference value can be obtained as enhanced calibration reference value information. For example, the TX can request the enhanced calibration reference value information from the RX.

[0110] In the case where the received power in the power receiving device changes to a value exceeding a predetermined value, the enhanced calibration reference value information can be transmitted.

[0111] In the case where a predetermined condition is satisfied, the TX does not need to start the above-mentioned timer. That is, the TX can be configured to not execute Figure 5 Or Figure 6A And Figure 6B The processing operations associated with timeout shown. The TX can be configured such that, for example, in the case of power transmission and reception using a received power closer to the received power represented by the valid calibration reference value information obtained in the past, or in the case of power transmission and reception using a received power within the range of calculating an estimated value using a plurality of calibration reference value information, the timer is not started. The TX can be configured to not start the timer when the number of times of calculating an estimated value using the valid calibration reference value information obtained in the past becomes greater than or equal to a predetermined number of times. Therefore, in the case where the accuracy of foreign object detection is sufficiently ensured, the occurrence of unnecessary timeouts and unnecessary changes in the transmission output can be suppressed.

[0112] In the above example, after a timeout occurs, the target value is set within the range of the received power for which the estimated value of the power loss has been calculated. However, a received power outside the above range and having a difference from the received power for which the estimated value of the power loss has been calculated less than a threshold value can be used as the target value. This enables charging to continue as quickly as possible without significantly affecting the accuracy of foreign object detection using the calculated estimated value.

[0113] In the above example, after a timeout occurs, the TX changes the transmission output so that the received power has the target value. However, negotiation can be performed again between the TX and the RX, and the GP can be changed to the target value. At this time, negotiation is performed such that the target value is a value within the range from the minimum value to the maximum value of the received power represented by the valid calibration reference value information. Therefore, the maximum value of the received power that the RX can receive can be kept at the target value or less, thereby enabling charging to continue while suppressing a decrease in the accuracy of foreign object detection.

[0114] After a timeout occurs, the TX can determine that some problem has occurred during the charging process and stop power transmission. This makes it possible to suppress the occurrence of problems caused by undetected foreign objects or incorrect operations, etc. After stopping power transmission, the TX can return the process to the selection phase in S401. Therefore, if it becomes difficult to continue power transmission due to, for example, a positional shift of the RX, the predetermined process for starting charging can be re-executed, thereby appropriately restarting charging. If an abnormality is detected, the TX can limit power transmission to reduce the power to be transmitted.

[0115] In the above example, after a timeout occurs, the TX transmits a NAK to the RX for the received power information to change the power transmission output so that the received power has a target value. At this time, the TX can transmit a response including additional information. For example, the TX can include in the NAK to be transmitted a notification for changing the power transmission output, the reason for changing the power transmission output, the target value of the received power, the criteria for determining the timeout, and a request for transmitting additional calibration reference value information, etc. These pieces of information can be transmitted using a separate response signal / message different from the NAK. All the additional information can be transmitted using one response signal or message, or multiple response signals or messages can be used to transmit the additional information in a distributed manner. Such additional information enables the RX to notify the user via display, etc. using, for example, the display unit 207 that fast charging is restricted, so user convenience can be improved. In addition, the RX can use the reception of the additional information as a trigger to transmit additional calibration reference value information, so it is possible to avoid a change in the power transmission output in the TX and continue fast charging.

[0116] After a timeout occurs, the TX can use the display unit 307 to ask the user whether to continue fast charging and can determine whether to change the power transmission output based on the instruction received via the operation unit 308. For example, in the case where an instruction to continue fast charging is given within a predetermined time from the start of the inquiry, the TX can be configured to transmit an ACK to the received power information without changing the power transmission output. This process can be performed using the display unit 207 and the operation unit 208 of the RX. For example, the RX can be configured to start asking the user using the reception of the above additional information as a trigger and can be configured not to transmit a power transmission output change instruction indicating a reduction in the power transmission output in the case where an instruction to continue fast charging is given within a predetermined time. Therefore, in the case where the user can determine that no foreign object, etc. has been incorporated, an unnecessary change in the power transmission output can be suppressed, thereby continuing fast charging.

[0117] In the above example, when increasing the received power in the RX, if calibration reference value information is not received within a predetermined time or longer, the transmission output is decreased (or not increased). The same process can also be performed when decreasing the received power in the RX. That is, the target value for changing the transmission output can be a received power greater than the received power at this time, and the TX can increase the transmission output so that the received power in the RX increases. For example, the TX can use the maximum received power among all the received powers represented by the valid calibration reference value information obtained in the past as the target value. In this case, the RX transmits a transmission output change instruction indicating an increase in the transmission output to the TX. This enables charging to continue as fast as possible using the received power that can accurately detect foreign objects.

[0118] In the above example, the TX calculates an estimated value of the power loss. However, the present invention is not limited to this. That is, the TX only needs to obtain information for associating the transmission output with the received power in the RX that can be obtained at that transmission output. For example, the TX only needs to obtain the combination of the received power Pr1 of the first calibration reference value and the transmission output Pt1 at this time, and the combination of the received power Pr2 of the second calibration reference value and the transmission output Pt2 at this time. Also in this case, for example, for the received power Pr3 between Pr1 and Pr2, the value obtained by (Pt2 - Pt1) / (Pr2 - Pr1)×(Pr3 - Pr1)+Pt1 can be compared with the actual transmitted power, and if the absolute value of the difference exceeds a predetermined value, the presence of a foreign object can be detected.

[0119] Other embodiments

[0120] The present invention can be implemented by the following process: supplying a program for implementing one or more functions of the above embodiments to a system or device via a network or a storage medium, and causing one or more processors in the computer of the system or device to read and execute the program. The present invention can also be implemented by a circuit (e.g., ASIC) for implementing one or more functions.

[0121] The present invention is not limited to the above embodiments, and various changes and modifications can be made within the spirit and scope of the present invention. Therefore, the appended claims are added to inform the public of the scope of the present invention.

Claims

1. A power transmission device, comprising: a power transmission component for wirelessly transmitting power to a power receiving device; a communication component for communicating with the power receiving device; a processing component for performing a detection process for detecting an object different from the power receiving device using power loss when wirelessly transmitting power using the power transmission component; an acquisition component for obtaining reference value information related to a reference value of received power for obtaining the power loss from the power receiving device using the communication component; and a control component for performing predetermined control when the power loss has been obtained and a predetermined time has elapsed in a state where no valid reference value information has been obtained since a predetermined timing associated with the timing of obtaining information from the power receiving device, the predetermined control being control for preventing an increase in the power transmission output in the power transmission component regardless of the received power in the power transmission device.

2. The power transmission device according to claim 1, wherein the predetermined timing is defined based on the timing of obtaining valid reference value information from the power receiving device or the timing of the communication component transmitting an affirmative acknowledgment to the power receiving device, the affirmative acknowledgment indicating acceptance of the reference value information in response to obtaining the reference value information from the power receiving device.

3. The power transmission device according to claim 1 or 2, wherein the predetermined timing is defined based on the timing when the difference between the received power indicated by the reference value information determined to be obtained using the communication component and the received power indicated by the valid reference value information obtained in the past is greater than or equal to a threshold value, or the timing of transmitting an affirmative acknowledgment indicating acceptance of the reference value information to the power transmission device.

4. The power transmission device according to any one of claims 1 to 3, wherein the communication component receives received power information different from the reference value information and indicating the received power in the power receiving device, and the predetermined timing is defined based on the timing when the difference between the received power indicated by the received power information and the received power indicated by the valid reference value information obtained in the past is greater than or equal to a threshold value, or the timing of transmitting a response to the received power information to the power receiving device.

5. The power transmission device according to any one of claims 1 to 4, wherein in response to the communication component receiving a change instruction for instructing a change in the power transmission output from the power receiving device, the control component controls the power transmission output, and the predetermined timing is defined based on the timing when the change amount of the power transmission output caused by the change instruction with respect to the power transmission output in the case of obtaining valid reference value information is greater than or equal to a threshold value, or the timing of transmitting a response to the change instruction to the power receiving device.

6. The power transmission device according to any one of claims 1 to 5, wherein The predetermined timing is defined based on the timing of receiving information from the power receiving device via the communication component, or the timing of transmitting a response to information for ending negotiation, where the information for ending negotiation is information for ending negotiation of the received power that the power receiving device will obtain through power transmission.

7. The power transmission device according to any one of claims 1 to 6, wherein, the control component does not perform the predetermined control during a period when the predetermined timing is not defined.

8. The power transmission device according to any one of claims 1 to 7, wherein, the control component counts the number of times a response indicating that the communication component does not accept the reference value information although the reference value information is received is transmitted during a period when valid reference value information is not obtained after the predetermined timing, and performs the predetermined control when the number reaches a predetermined number.

9. The power transmission device according to any one of claims 1 to 7, wherein, the control component counts the number of times information different from the reference value information is received from the power receiving device during a period when valid reference value information is not obtained after the predetermined timing, and performs the predetermined control when the number reaches a predetermined number.

10. A computer-readable storage medium for storing a program for causing a computer to function as the power transmission device according to any one of claims 1 to 9.

Images