Power transmission device, control method and computer readable storage medium

Abstract

A power transmitting device configured to wirelessly transmit power to a power receiving device performs the following operations: when performing wireless power transmission, performs detection processing for detecting an object different from the power receiving device using power loss; obtains reference value information related to a reference value of received power for obtaining power loss from the power receiving device; and performs predetermined control that prevents a power transmission output from increasing regardless of received power in the power receiving device after the power loss is obtained and when a predetermined time has passed without obtaining valid reference value information since a predetermined timing associated with a timing of obtaining information from the power receiving device.

Description

Technical Field

[0001] The present invention relates to a technology for controlling transmission power and reception power in wireless power transmission. Background Art

[0002] The technology used in wireless power transmission systems has 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 power reception in accordance with a standard (WPC standard) specified by the Wireless Power Consortium (WPC), which is a standardization organization for wireless charging standards. In this method, the received power at a past time point and the received power at a current time point are compared, and in the case where the received power does not increase despite the fact that control is performed to increase the transmission power, or in the case where the received power does not decrease despite the fact that control is performed to reduce the transmission power, it is determined that a foreign object exists.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-165761 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] It is conceivable that, for example, due to changes in the power transmission and power receiving environment, even if the same power is transmitted, the received power gradually changes. At this time, if the information at the 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 lead to various problems that reduce convenience, such as charging stop due to false detection and temperature increase caused by failure to detect the presence of foreign objects.

[0008] Solutions for solving problems

[0009] The present invention provides a technology for improving the convenience of wireless power transmission.

[0010] A power transmitting device according to an aspect of the present invention includes: a power transmitting unit for wirelessly transmitting power to a power receiving device; a communication unit for communicating with the power receiving device; a processing unit for performing a detection process for detecting an object different from the power receiving device using a power loss when the power transmitting unit is used for wireless power transmission; an obtaining unit for obtaining, from the power receiving device, reference value information related to a reference value of received power for obtaining the power loss using the communication unit; and a control unit for performing a specific control that prevents an increase in output power using the power transmitting unit regardless of the received power of the power transmitting device after the power loss is obtained and when a predetermined time has passed since a predetermined timing associated with a timing of obtaining the information from the power receiving device without obtaining valid reference value information.

[0011] Effects of the Invention

[0012] According to the present invention, the convenience of wireless power transmission can be improved.

[0013] 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 represent the same or similar components. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0015] Figure 1 is a diagram showing the structure of a wireless charging system.

[0016] Figure 2 is a diagram showing a configuration example of a power receiving device.

[0017] Figure 3 is a diagram showing a structural example of a power transmission device.

[0018] Figure 4 is a flowchart illustrating an example of the flow of processing performed by the power transmission device.

[0019] Figure 5 : is a flowchart illustrating an example of the flow of a power transmission control process executed by a power transmission device.

[0020] Fig. 6A : is a flowchart illustrating an example of the flow of timeout processing executed by the power transmitting device.

[0021] Figure 6B : is a flowchart illustrating an example of the flow of timeout processing executed by the power transmitting device.

[0022] Figure 7 is a flowchart illustrating an example of the flow of a process executed by a power receiving apparatus.

[0023] Figure 8 is a flowchart illustrating an example of the flow of a power reception control process executed by a power receiving apparatus.

[0024] Fig. 9A is a diagram showing a communication sequence in a calibration phase.

[0025] Fig. 9B is a diagram showing a communication sequence used for device authentication.

[0026] Fig. 10A is a diagram showing a first example of the flow of processing executed in the system.

[0027] Fig. 10B is a diagram showing a first example of the flow of processing executed in the system.

[0028] Fig.11A is a diagram showing a second example of the flow of processing executed in the system.

[0029] Fig. 11B is a diagram showing a second example of the flow of processing executed in the system. DETAILED DESCRIPTION

[0030] Embodiments will be described in detail below with reference to the accompanying drawings. Note that the following embodiments are not intended to limit the scope of the claimed invention. A number of features are described in these embodiments, but are not limited to inventions requiring all of these features, and a number of such features may be appropriately combined. In addition, in the accompanying drawings, the same reference numerals are assigned to the same or similar structures, and redundant descriptions of these structures are omitted.

[0031] (System Structure)

[0032] Figure 1An example of the structure of a wireless charging system (wireless power transmission system) according to the present embodiment is shown. In the example, the present 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". RX is an electronic device that receives power from the power transmitting device 102 and charges an internal battery. TX is an electronic device that wirelessly transmits power to RX placed on a charging stand 103. Range 104 indicates a range in which RX can receive power transmitted from TX. RX and TX may have functions for executing applications other than wireless charging. An example of RX is a smartphone, and an example of TX is an accessory device for charging a smartphone. RX and TX may each 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, RX and TX may each be an image input device such as a camera (camera, video camera, etc.) and a scanner, or may be an image output device such as a printer, a copier, and a projector. Alternatively, TX may be a smartphone. In this case, RX may be another smart phone, or may be a peripheral device such as a wireless headset, etc. Alternatively, RX may be a car. Alternatively, TX may be a charger installed in a console, etc., in a car.

[0033] This system performs wireless power transmission using an electromagnetic induction method used for wireless charging according to the WPC standard specified by the WPC (Wireless Power Consortium). That is, RX and TX perform wireless power transmission for wireless charging according to the WPC standard between the power receiving coil of RX and the power transmitting coil of TX. The method of wireless power transmission is not limited to the method defined in the WPC standard, and may be another electromagnetic induction method, a magnetic resonance method, an electric field resonance method, a microwave method, or a method using laser or the like. Although wireless power transmission is used for wireless charging in this embodiment, wireless power transmission may be performed for purposes other than wireless charging.

[0034] In the WPC standard, the power guaranteed when RX receives power from TX is defined by a value called "guaranteed power" (hereinafter referred to as "GP"). GP represents a value that guarantees the power output to a load such as a charging circuit of RX even if 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 RX and TX. For example, when GP is 5W, TX transmits power while performing control so that 5W can be output to the load in RX 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.

[0035] The RX and TX according to the present 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.

[0036] The WPC standard defines a plurality of phases (including a power transmission phase in which power transmission is performed and a phase before actual power transmission is performed), and performs communication for power transmission / power receiving 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, 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 station 103, etc.). In the Ping phase, TX transmits a digital Ping and identifies that the detected object is RX by receiving a response from RX that receives the digital Ping. In the configuration phase, RX notifies TX of identification information and capability information. In the negotiation phase, a negotiation is performed to determine the value of GP based on the value of GP requested from RX or the power transmission capability of TX, etc. In the calibration phase, RX notifies TX of the received power value according to the WPC standard, and TX performs adjustments for foreign object detection during power transmission. In the power transmission phase, control is performed for, for example, continuing power transmission and stopping power transmission due to an error or full charge. TX and RX use in-band communication to perform these communications for power transmission and power reception control, in which signals are superimposed using the same antenna (coil) used for wireless power transmission according to the WPC standard. The range in which in-band communication according to the WPC standard can be performed between TX and RX is basically the same as the power transmission range. That is, in Figure 1 In the range 104, the range 104 indicates the range in which wireless power transmission and in-band communication can be performed using the power transmission coil and the power receiving coil of TX and RX. In the following description, "placing" RX means that RX enters the range 104, and includes the state that RX is not actually placed on the charging station 103.

[0037] TX and RX may use an antenna (coil) different from the antenna (coil) used for wireless power transmission for communication (out-of-band communication) used for power transmission / power reception control. Examples of communication using an antenna (coil) different from the antenna (coil) used for wireless power transmission include communication methods that comply with the Bluetooth (registered trademark) low power consumption standard. Alternatively, other communication methods such as IEEE 802.11 standard wireless LANs (e.g., Wi-Fi (registered trademark), ZigBee, and NFC (near field communication)) may be used. Communication using an antenna (coil) different from the antenna (coil) used for wireless power transmission may be performed at a frequency different from the frequency used for wireless power transmission.

[0038] In the present embodiment, before determining the GP, RX performs a challenge-response communication using an electronic certificate with TX, and performs device authentication on TX. That is, RX performs communication used for device authentication of TX. Then, based on the result of device authentication, RX determines the GP requested from TX in the above-mentioned negotiation phase. For example, RX determines the GP requested from TX in which device authentication is successful to be 15W, and determines the GP requested from TX in which device authentication is unsuccessful to be 5W. The GP requested from TX is not limited to a combination of 15W and 5W. For example, a combination of the following arbitrary values ​​may be used, in which the GP requested from TX in which device authentication is successful is greater than the GP requested from TX in which device authentication is unsuccessful. Therefore, RX can transmit / receive power with a large GP only with TX in which device authentication is successful. By determining the GP based on the result of device authentication in this way, RX is able to receive power with a large GP only from a TX in which the TX has passed a predetermined test defined in the WPC standard, etc. and is considered to be able to transmit power with a large GP.

[0039] (Equipment Structure)

[0040] Next, the structure of the power receiving device 101 (RX) and the power transmitting device 102 (TX) according to the present embodiment will be described. The components described below are merely examples. Some (possibly all) of the components described may be replaced by another structure serving the same function, or may be omitted, and more components may be added to the components described. In addition, one block described in the following description may be divided into a plurality of blocks, and a plurality of blocks may be integrated into one block.

[0041] Figure 2 2 is a diagram showing a configuration example of an RX according to the present 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.

[0042] The control unit 201 performs overall control of RX, for example, by executing a control program stored in the memory 209. In the example, the control unit 201 performs control required for device authentication and power reception in RX. The control unit 201 can perform control for executing applications other than wireless power transmission. 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 a specific process (such as an application-specific integrated circuit (ASIC)), and an array circuit (such as a field programmable gate array (FPGA)) compiled to perform a predetermined process. The control unit 201 causes the memory 209 to store information to be stored when various processes are being performed. In addition, the control unit 201 can use a timer 210 to measure time.

[0043] The battery 202 supplies the entire RX with power required for control, power reception, and communication. In addition, the battery 202 stores power received via the power receiving coil 205. In the power receiving coil 205, an induced electromotive force is generated by the electromagnetic wave emitted from the power transmission coil 305 of the TX, and the power receiving unit 203 obtains the power generated in the power receiving coil 205. The power receiving unit 203 obtains the AC power generated by electromagnetic induction in the power receiving coil 205. Then, the power receiving 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 receiving unit 203 supplies power to the load of the RX. The above-mentioned GP is to ensure the power output from the power receiving unit 203.

[0044] The detection unit 204 detects whether the RX is placed in the range 104 where it can receive power from the RX according to the WPC standard. For example, the detection unit 204 detects the voltage value or the current value of the power receiving coil 205 when the power receiving unit 203 receives the digital Ping of the WPC standard via the power receiving 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 can determine that the RX is placed in the range 104.

[0045] The communication unit 206 uses in-band communication to perform control communication with TX according to the WPC standard as described above. The communication unit 206 demodulates the electromagnetic wave input from the power receiving coil 205 to obtain information transmitted from TX, and superimposes the information to be transmitted to TX on the electromagnetic wave by load modulating the electromagnetic wave, thereby communicating with TX. That is, the communication performed by the communication unit 206 is performed by superimposing information on the power transmitted from the power transmission coil 305 of TX. The communication unit 206 can perform out-of-band communication with TX.

[0046] The display unit 207 presents information to the user through 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 Figure 1 The state of the wireless power transmission system including TX and RX 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 an acceptance function of accepting operations on RX from the user. The operation unit 208 includes, for example, an audio input device (such as a button, a keyboard, and a microphone), a motion detection device (such as an acceleration sensor and a gyro sensor), or other input devices. A device (such as a touch panel, etc.) in which the display unit 207 and the operation unit 208 are integrated can be used. As described above, the memory 209 stores various information. The memory 209 can store information obtained by a functional unit different from the control unit 201. The timer 210 measures time using, for example, an up-counting timer for measuring the time elapsed from the moment the timer is started or a down-counting timer for counting down from a set time.

[0047] Figure 3 30 is a diagram showing a configuration example of a 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.

[0048] The control unit 301 performs overall control of TX, for example, by executing a control program stored in the memory 309. In the example, the control unit 301 performs control required for device authentication and power transmission in TX. 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 may include hardware dedicated to a specific process (such as an application-specific integrated circuit (ASIC)), and an array circuit (such as a field programmable gate array (FPGA)) compiled to perform a predetermined process. The control unit 301 causes the memory 309 to store information to be stored when various processes are being performed. In addition, the control unit 301 can use a timer 310 to measure time.

[0049] The power supply unit 302 supplies the entire TX with power required for control, power transmission, and communication. The power supply unit 302 is, for example, a commercial power supply or a battery.

[0050] 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 to 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, 110kHz to 205kHz). According to the instruction from the control unit 301, the power transmission unit 303 inputs the AC frequency power to the power transmission coil 305, so that the electromagnetic wave for power transmission to the RX is 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 wave to be output. When the transmission voltage or the transmission current increases, the intensity of the electromagnetic wave increases. When the transmission voltage or the transmission current decreases, the intensity of the electromagnetic wave decreases. According to the instruction from the control unit 301, the power transmission unit 303 controls the output of the AC frequency power so that the power transmission from the power transmission coil 305 is started or stopped.

[0051] The detection unit 304 detects whether an object exists in the range 104 according to the WPC standard. For example, the detection unit 304 detects a voltage value or a 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 a predetermined current value, the detection unit 304 can determine that an object exists in the range 104. Regarding the determination of whether the object is an RX or any other foreign object, if a predetermined response is received for a digital Ping subsequently transmitted by the communication unit 306 using in-band communication, it is determined that the object is an RX.

[0052] The communication unit 306 uses in-band communication to perform control communication with the RX according to the WPC standard as described above. The communication unit 306 modulates the electromagnetic wave output from the power transmission coil 305 and transmits information to the RX. The communication unit 306 demodulates the electromagnetic wave 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, the 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.

[0053] The display unit 307 presents information to the user through any method such as visual, audio or tactile methods. For example, the display unit 307 notifies the user of the status of the TX or Figure 1The information of the state of the wireless power transmission system including TX and RX shown. The display unit 307 includes, for example, a liquid crystal display, an LED, a speaker, a vibration generating circuit or other notification device. The operation unit 308 has an acceptance function of accepting an operation on TX from a user. The operation unit 308 includes, for example, an audio input device (such as a button, a keyboard, and a microphone), a motion detection device (such as an acceleration sensor and a gyro sensor, etc.), or other input devices. A device (such as a touch panel, etc.) in which the display unit 307 and the operation unit 308 are integrated 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 using, for example, an up-counting timer for measuring the time elapsed from the moment the timer is started or a down-counting timer for counting down from a set time.

[0054] (Processing Flow Executed by Power Transmission Equipment)

[0055] Next, an example of the flow of processing executed by TX will be described. Figure 4 An example of a flow of processing performed by TX is shown. This processing can be implemented, for example, by the control unit 301 of TX executing a program read from the memory 309. At least 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. This processing can be performed in response to turning on TX, in response to a user input of TX to start a wireless charging application, or in response to TX being connected to a commercial power supply and receiving power therefrom. Optionally, other triggers can be used to start this processing.

[0056] In this process, TX first performs the process defined as the selection phase and the Ping phase in the WPC standard, and waits for RX to be placed (S401). In these phases, TX repeatedly and intermittently transmits the analog Ping of the WPC standard, and detects an object existing in the power transmission range. Then, if the existence of an object in the power transmission range is detected, TX transmits the digital Ping of the WPC standard. If a predetermined response to the digital Ping is received, TX determines that the detected object is RX and RX is placed on the charging station 103.

[0057] If it is detected in S401 that RX is placed, TX uses the communication in the configuration phase defined in the WPC standard to obtain identification information and capability information from RX (S402). Here, the identification information of RX includes a manufacturer code and a basic device ID. The capability information of RX includes information elements that can specify the version of the corresponding WPC standard, a maximum power value (which is a value that specifies the maximum power that RX can supply to the load), and information indicating whether RX has a negotiation function of the WPC standard. These are just examples, and the identification information and capability information of RX can be replaced by other information, or may include other information in addition to the above information. For example, the identification information can be any other identification information (such as a wireless power ID, etc.) that can identify an individual RX. TX can obtain the identification information and capability information of RX by methods other than communication in the configuration phase of the WPC standard.

[0058] Subsequently, TX negotiates with RX using communication in the negotiation phase defined in the WPC standard to determine the value of GP (S403). The process performed in S403 is not limited to the communication in the negotiation phase of the WPC standard, and another process for determining GP may be performed. If TX (for example, in S402) obtains information indicating that RX does not correspond to the negotiation phase, TX may determine the value of GP to a small value (for example, a value predefined in the WPC standard) without performing communication in the negotiation phase.

[0059] After determining the GP, TX performs calibration based on the determined GP (S404). Calibration is a process for calibrating the correlation between the value of the transmission output (which is the value measured by TX in its own device) and the value of the received power (which is the value measured by RX in its own device) for the power transmitted by TX to RX. For example, TX estimates the power loss that can be determined as the difference between the value of the transmission output and the value of the received power based on the value of the received power received from RX as a reference value for calibration and the value of the transmission output set when obtaining the received power used as the reference value. In the calibration process, when the state of RX is two different states from each other, the transmission power of TX and the received power of 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 value of the slope and the value of the intercept 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 group of transmission power and reception power, and can be a group of transmission power and power loss, or can be a group of reception power and power loss.

[0060] like Fig. 9AAs shown in FIG. 1 , during calibration, the communication in the calibration phase of the WPC standard is performed. In this process, as Fig. 9A As shown, first, RX transmits information including received power in a light load state used as a first calibration reference value (hereinafter referred to as "first calibration reference value information") to TX (F901). Here, for example, the received power (mode 1) as a message defined in the WPC standard is used to transmit and receive the first calibration reference value information. However, other messages may be used. TX determines whether to accept the first calibration reference value information based on its own power transmission state. If TX accepts the first calibration reference value information, TX transmits a positive acknowledgement (ACK) to RX, and if TX does not accept the first calibration reference value information, TX transmits a negative acknowledgement (NAK) to RX (F902). Here, for example, if TX determines that its own power transmission state is stable, TX accepts the notification, and if TX determines that its own power transmission state is unstable, TX does not accept the notification. The calibration reference value information accepted by TX may be referred to as valid calibration reference value information. If RX receives NAK from TX, RX transmits the first calibration reference value information again. On the other hand, if RX receives ACK from TX, RX transmits information including the received power in the load connection state used as the second calibration reference value to TX (hereinafter referred to as "second calibration reference value information") (F903). Here, for example, the received power (mode 2) as a message defined in the WPC standard is used to transmit and receive the second calibration reference value information. However, other messages may be used. TX determines whether to accept the second calibration reference value information based on its own power transmission state. As in F902, if TX accepts the second calibration reference value information, TX transmits ACK to RX, and if TX does not accept the second calibration reference value information, TX transmits NAK to RX (F904). If RX receives NAK from TX, RX transmits the second calibration reference value information again. When transmitting ACK to RX, TX specifies the corresponding power loss when using the two reference values ​​based on the received power included in the first calibration reference value information and the second calibration reference value information. Then, TX estimates the power loss when receiving a received power of a value different from the two reference values, for example, using linear interpolation based on the two specified power loss values. If TX fails to transmit ACK as a response to the second calibration reference value information within a predetermined time after the negotiation phase (S403) is completed, TX may determine that the calibration has failed and may stop power transmission. Calibration may be performed by a method other than the method of the WPC standard.

[0061] After the calibration is completed, TX starts power transmission (S405). Power transmission is performed by the process in the power transmission stage of the WPC standard. However, power transmission is not limited thereto, and may be performed by a method other than the method of the WPC standard.

[0062] Then, TX and RX communicate for device authentication (S406). Fig. 9B To illustrate the communication used for device authentication 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 the other device. RX operates as an initiator that transmits a challenge text to TX, and TX operates as a 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 requesting information related to an electronic certificate owned by the recipient (TX) of the message. In response to GET_DIGESTS, TX transmits DIGESTS (digest) to RX (F912). DIGESTS is a message including information related to an electronic certificate owned by the transmitter (TX) of the message. Subsequently, RX transmits a GET_CERTIFICATE message (F913) requesting detailed information related to the electronic certificate to TX. In response to GET_CERTIFICATE from RX, TX transmits CERTIFICATE (certificate) to RX (F914). Then, RX transmits a CHALLENGE (challenge) message including a challenge text to TX (F915), and TX transmits CHALLENGE_AUTH obtained by encrypting the challenge text received from RX to RX (F916). RX determines that the device authentication is successful when the correctness of CHALLENGE_AUTH received from TX is verified, and determines that the device authentication fails when the correctness cannot be verified. When this judgment is completed, the device authentication process ends.

[0063] If the initiator (RX) receives a message indicating that the other device (TX) does not support the communication used 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) may retry, for example, by resending a message for obtaining a response, or may determine that the other device (TX) does not support device authentication. RX may be configured not to communicate with a TX that does not support device authentication for device authentication, and not to judge the result of device authentication as successful. Here, it is assumed that the device authentication is successful in S406.

[0064] Return to reference Figure 4, TX together with RX redetermines 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 as GP is a value greater than 5W (for example, 15W). After redetermining GP, TX repeats the power transmission control process (S408). If the end of power transmission of the WPC standard is received from RX, TX ends the processing performed in any processing phase according to the WPC standard and stops power transmission, and then returns to the selection phase in S401. In the case of reaching a fully charged state, the end of power transmission is also transmitted from RX. Therefore, TX returns to the selection phase in S401.

[0065] Reference Figure 5 408. The present invention will now be described with reference to an example of the flow of the power transmission control process performed by the TX in S408. 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 process can be implemented with 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 process steps using a predetermined compiler.

[0066] Using the start of the process as a trigger, TX starts a timer until the calculation of the estimated value of the power loss is completed (S501). The timer can be started using the start of the process 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. However, the present invention is not limited to this, and for example, the completion of the calculation of the estimated value of the 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 performed by including a control error value as a value representing the amount of change in voltage in the control error message of the WPC standard. In the control error value, if the power transmission output is to be increased, a positive value is stored, if the power transmission output is to be reduced, a negative value is stored, and if the power transmission output is not to be changed, 0 is stored. If a power output change instruction is received (Yes in S502), TX changes the power output based on the instructed change amount (S503), and advances the process to S504. On the other hand, if a power output change instruction is not received (No in S502), TX advances the process to S504 without performing any operation.

[0067] In S504, TX determines whether the reception power information is received from RX. Here, the reception power information is information including the reception power actually received in RX at this point in time. The reception power information is transmitted and received using the reception power (mode 0) message defined in the WPC standard. However, the present invention is not limited to this. If the reception power information is received ("Yes" in S504), TX transmits ACK (S505) and causes the processing to enter S506. On the other hand, if the reception power information is not received ("No" in S504), TX causes the processing to enter S506 without performing any operation.

[0068] In S506, TX determines whether enhanced calibration reference value information is received from RX. Here, the enhanced calibration reference value information is information of received power in a load connection state including a reference value used for additional calibration for calculating an estimated value of power loss. If enhanced calibration reference value information is received ("Yes" in S506), TX causes the process to enter S507, and if enhanced calibration reference value information is not received ("No" in S506), TX causes the process to enter S511. In S507, TX determines whether to accept the enhanced calibration reference value information received in S506. Here, 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 to this. For example, if the power loss of the received power represented by the enhanced calibration reference value information deviates from the calculated estimated value of power loss by more than a predetermined value, TX can determine that the enhanced calibration reference value information is not accepted.

[0069] If TX accepts the enhanced calibration reference value information (Yes in S507), TX calculates the estimated value of power loss based on the received power represented by the enhanced calibration reference value information (S508), and transmits ACK to RX (S509). The calculation of the estimated value of power loss and the transmission of ACK can be performed in reverse order, or can be performed simultaneously (the processing time periods of the two can overlap at least partially). Then, TX resets the timer (S513) and ends the processing. The estimated value of power loss is estimated, for example, based on the following two: the first power loss at the first received power represented by the enhanced calibration reference value information received in S506, and the second power loss estimated based on the second received power represented 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 to be (L2-L1) / (P2-P1)×(P-P1)+L1. However, the method for estimating power loss is not limited to linear interpolation. For example, based on at least one calibration reference value information received in and after the calibration phase, a statistical analysis such as linear approximation and polynomial approximation can be used to calculate an estimated value of power loss. An estimation method can be selected from these estimation methods based on the amount of calibration reference value information available and the computing resources of the TX. Therefore, when computing resources are sufficient, a highly accurate estimate can be calculated by performing statistical analysis using a larger amount of calibration reference value information. When computing resources are insufficient, the computing time required for the calculation can be reduced by performing simple estimation such as linear interpolation.

[0070] On the other hand, if TX does not accept the enhanced calibration reference value information (No in S507), TX transmits NAK to RX (S510), and determines whether a timeout has occurred (S511). TX can determine whether a timeout has occurred based on whether the calculation of the estimated value of the power loss is completed within a predetermined time after the timer is started in S501. That is, if a predetermined time has passed without receiving the enhanced calibration reference value information from RX, or if a predetermined time has passed without transmitting ACK for the enhanced calibration reference value information, TX can determine that a timeout has occurred. Instead of measuring time with a timer or in addition to measuring time with a timer, TX can determine whether the number of receptions of the power transmission output change indication received from RX or the number of receptions of predetermined information other than the calibration reference value information (such as received power information received from RX) becomes greater than or equal to a predetermined number of times. For example, in S501, when starting the timer, or instead of starting the timer, TX can reset the number of receptions of the indication or information to 0, count the number of receptions each time TX receives the indication or information, and determine whether the number of receptions reaches the predetermined number of times in S511. Instead of or in addition to measuring time with a timer, TX may determine whether the number of transmissions of NAK for the received enhanced calibration reference value information becomes greater than or equal to a predetermined number of times. Also in this case, TX may reset the number of transmissions of NAK to 0 in S501, increment the number of transmissions each time TX transmits NAK, and determine in S511 whether the number has reached a predetermined number of times. If it is determined that a timeout has occurred ("Yes" in S511), TX performs a timeout process (S512). When the timeout process is completed, TX resets the timer (S513) and ends the present process. The timeout process in S512 will be described later. On the other hand, if it is determined that a timeout has not occurred ("No" in S511), TX returns the process to S502.

[0071] As mentioned above, TX repeatedly executes Figure 5The process shown. By repeatedly performing this process and sequentially updating the estimated value of power loss using enhanced calibration reference value information, the accuracy of foreign object detection can be prevented from decreasing by performing foreign object detection based on the latest estimated value of power loss. As a result, charging suspension due to false detection of foreign objects and temperature rise caused by failure to detect the presence of foreign objects can be prevented, thereby improving convenience. If the timer is reset in S513, the timer in S501 can be started at this point in time. 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 power loss, and the timing of transmitting ACK). During the timeout process, the timer can be reset at a predetermined timing such as the following: the reception timing of the received power information indicating the received power that has been reduced to the target value, the reception timing of the valid enhanced calibration reference value information, and the transmission timing of the ACK for these information.

[0072] Next, refer to Fig. 6A and Figure 6B To illustrate Figure 5 The process of the timeout process performed in S512 of TX is described in detail. This process 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 process 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 FPGA, etc.) from a program for implementing the process steps using a predetermined compiler.

[0073] After starting the process, TX determines whether a power output change instruction is received from RX (S601). If a power output change instruction is received ("Yes" in S601), TX causes the process to proceed to S602, and if a power output change instruction is not received ("No" in S601), TX causes the process to proceed to S605. In S602, TX determines whether the power output change instruction is an instruction to increase the power 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 output change instruction indicates an increase in the power output ("Yes" in S602), TX does not change the power output (S603) and causes the process to proceed to S605. That is, in the case where it is determined that a timeout has occurred, for example, based on the fact that a certain time has passed without obtaining any new calibration reference value after updating the calibration reference value, TX is configured to increase the power output without complying with the power output change instruction. In the case where the accuracy of foreign matter detection decreases as a result of the lack of accuracy of the calibration reference value information after a long time has passed since the calibration reference value was updated, the TX may determine that there is no foreign matter despite the presence of the foreign matter. Therefore, it is possible to prevent temperature increase, etc. by configuring the TX not to increase the power output in an environment where the foreign matter exists but the presence of the foreign matter may not be detected. On the other hand, if it is determined that the power output change instruction is not an instruction to increase the power output ("No" in S602), the TX changes the power output based on the indicated change amount (S604), and causes the process to proceed to S605.

[0074] In S605, TX determines whether the reception power information is received from RX (S605). If the reception power information is received ("Yes" in S605), TX causes the processing to enter S606, and if the reception power information is not received ("No" in S605), TX causes the processing to enter S609. In S606, TX determines whether the reception power is reduced to the target value based on the received reception power information. Here, the target value may be set to a reception power that falls within the range of the GP before re-negotiation, but is not limited to this. For example, the target value may be set to the maximum reception power of the reception power represented by the last accepted (ACK has been transmitted) calibration reference value information, and the reception power represented by the calibration reference value information accepted in the past.

[0075] If it is determined that the received power has dropped to the target value ("Yes" in S606), TX transmits ACK (S607) and ends the present process. On the other hand, if it is determined that the received power has not dropped to the target value ("No" in S606), TX transmits NAK (S608) and causes the process to proceed to S609. In S609, TX determines whether the enhanced calibration reference value information is received. If it is determined that the enhanced calibration reference value information is received ("Yes" in S609), TX causes the process to proceed to S610, and if it is determined that the enhanced calibration reference value information is not received ("No" in S609), TX returns the process to S601. As in the case of the first calibration reference value information and the second calibration reference value information, TX determines whether to accept the enhanced calibration reference value information (S610). Then, if TX accepts the enhanced calibration reference value information ("Yes" in S610), TX transmits ACK (S611), calculates the estimated value of power loss based on the enhanced calibration reference value information (S613), and ends this process. On the other hand, if TX does not accept the enhanced calibration reference value information ("No" in S610), TX transmits NAK (S612) and returns the process to S601. After completing this process, TX proceeds to S513 and repeats the process thereafter. Figure 5 Processing shown.

[0076] (Flow of Processing Executed by Power Receiving Device)

[0077] Next, an example of the flow of processing executed by the RX will be described. Figure 7 An example of a flow of processing performed by RX is shown. This processing can be implemented, for example, by the control unit 201 of RX executing a program read from the memory 209. At least a portion 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. This processing can be performed in response to starting RX as a result of turning on RX using power supplied from the battery 202 or TX, or in response to an indication from a user input of RX to start a wireless charging application. Optionally, other triggers can be used to start this processing.

[0078] After starting the process, RX performs the process defined as the selection phase and the Ping phase in the WPC standard, and waits for its own device to be placed on TX (S701). RX detects that its own device is placed on TX, for example, by detecting a digital Ping from TX. If it is determined that its own device is placed on TX, RX uses the communication in the configuration phase defined in the WPC standard to transmit identification information and capability information to TX (S702). After RX transmits the identification information and capability information, RX uses the communication in the negotiation phase defined in the WPC standard to determine the GP (S703). Here, since there is no communication used for device authentication, RX determines to negotiate so that the GP is 5W. Here, RX makes a reference based on the determined GP. Fig. 9A When the calibration is completed, the RX starts receiving power using the communication in the power transmission phase defined in the WPC standard (S705). After starting to receive power, the RX performs a reference Fig. 9B The communication used for device authentication (S706). It is assumed that the device authentication is successful. After that, RX negotiates and redetermines the value of GP together with TX (S707). Since the device authentication is successful, in S707, RX determines a value greater than 5W (for example, 15W) as GP. After redetermining GP, RX repeats the power receiving control process (S708). If an error occurs or if the full charge state is reached, RX transmits the end power transfer of the WPC standard. Therefore, the power transmission from TX is stopped, and a series of processes used for wireless charging are ended.

[0079] Next, refer to Figure 8 100 is a flowchart of the power receiving control process executed in S708. 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 process can be implemented by hardware. The hardware in this case can be implemented, for example, by automatically generating a dedicated circuit including a gate array circuit (such as FPGA, etc.) from a program for implementing the process steps using a predetermined compiler.

[0080] After starting the process, RX determines whether the received power is less than GP (S801). If it is determined that the received power is less than GP ("Yes" in S801), RX increases power consumption (S802), transmits a power output change instruction to TX indicating an increase in power output (S803), and causes the process to proceed to S805. On the other hand, if it is determined that the received power is greater than or equal to GP ("No" in S801), RX does not change power consumption, transmits a power output change instruction to TX indicating a maintenance of power output (S804), and causes the process to proceed to S805.

[0081] In S805, RX determines whether the transmission timing of the enhanced calibration reference value information has been reached. Here, the judgment on whether the transmission timing of the enhanced calibration reference value information has been reached can be made based on whether a predetermined time has passed after the negotiation is completed. However, the present invention is not limited to this. For example, RX can make a judgment in S805 based on whether the time elapsed after TX completes the calculation of the estimated value of power loss and RX receives an ACK for the calibration reference value information reaches a predetermined time. Alternatively, RX can use indicators other than the elapsed time to make the judgment in S805. For example, RX can judge 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. RX can use the difference between the received power represented by the calibration reference value information for which ACK was recently received and the current received power to judge whether the transmission timing of the enhanced calibration reference value information has been reached. This enables RX to reliably transmit enhanced calibration reference value information to TX in the presence of a certain amount of change in the received power, or in other words, in the case where the estimated value of the power loss of TX is assumed to have a large error.

[0082] If it is determined that the transmission timing of the enhanced calibration reference value information has been reached ("Yes" in S805), RX transmits the enhanced calibration reference value information including the current received power (S806), and determines whether NAK is received from TX (S807). If it is determined that NAK is received from TX for the transmitted enhanced calibration reference value information ("Yes" in S807), RX retransmits the enhanced calibration reference value information (S806). If NAK is received, RX can use the display unit 207 to display to prompt the user, for example, to reposition RX. Therefore, in the case where the power transmission in TX is unstable, for example, due to the position shift of TX, the predetermined process for starting charging can be re-executed, thereby restarting stable charging. On the other hand, if ACK is received for the enhanced calibration reference value information ("No" in S807), RX ends the present process without performing any operation.

[0083] 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), RX transmits the reception power information to TX at a predetermined time interval (S808), and determines whether NAK is received from TX (S809). If NAK is received from TX for the transmitted reception power information (Yes in S809), RX reduces power consumption (S810), transmits a transmission output change instruction (S811) indicating the reduction of the transmission output of TX to TX, and ends the present process. On the other hand, if ACK is received from TX for the received power information (No in S809), RX ends the present process without performing any operation.

[0084] As a result of RX periodically transmitting enhanced calibration reference value information in the increase phase 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. For example, when the transmission output is increasing, if the calibration reference value information is notified from RX to TX within a certain period of time, TX can obtain a new calibration reference value as follows, which is higher than the received power of the previously obtained calibration reference value and does not significantly deviate 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 RX to TX within a certain period of time, TX can obtain a new calibration reference value as follows, which is lower than the received power of the previously obtained calibration reference value and does not significantly deviate from the received power of these calibration reference values. In addition, by using this new calibration reference value, TX can accurately estimate 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 estimated 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 RX to TX within a certain period of time, TX can obtain the received power of the calibration reference value within a range where the received power relative to the existing calibration reference value does not deviate from the received power that exceeds a certain level. As a result, for example, TX can fully obtain the calibration reference value of the received power in a wide range, so that RX will not receive power that deviates significantly from the received power corresponding to the calibration reference value. This makes it possible to accurately estimate the power loss of any received power, thereby preventing the false detection of foreign objects and the failure of detecting the presence of foreign objects. If TX cannot obtain the enhanced calibration reference value information within a certain period of time during the increase or decrease phase of the transmission output, there is a possibility that the current received power deviates significantly from the received power of the calibration reference value. For this reason, a timeout judgment can be used, and if a timeout occurs, TX can be configured not to increase (or reduce) the transmission output, so that the transmission / reception of power that may reduce the accuracy of foreign object detection can be prevented.

[0085] The above-mentioned processing operation associated with the timeout can be performed only when the transmission output is increased (or decreased) to the 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 the power loss can be made without having to obtain an additional calibration reference value. For example, TX can set a validity period for each calibration reference value. In addition, TX can discard the reference value that exceeds the set validity period and perform the above-mentioned processing. For example, if the transmission output is to be increased / decreased so that the received power changes beyond the range of the received power specified by the reference value maintained in TX, TX can perform the above-mentioned processing operation associated with the timeout.

[0086] (Flow of processing executed in the system)

[0087] Several situations will be assumed to explain the operation sequence of the case where TX and RX perform the above-mentioned processing. It is assumed that in the initial state, RX is not placed on TX, and TX has a power transmission capability sufficient to perform power transmission at GP requested from RX.

[0088] <Processing Example 1>

[0089] First, refer to Fig. 10A and Fig. 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 is started. Then, after the power transmission starts, the device authentication succeeds, and the GP is re-determined to 15W by re-performing the negotiation. Using the completion of the negotiation as a trigger, or in other words, using the transmission of ACK for SRQ / en as a trigger, TX starts the timer. In addition, it is assumed that during the period when the received power in RX changes from 5W to 15W, TX can neither receive the enhanced calibration reference value information nor transmit ACK within a predetermined time. At this time, the TX of this processing example reduces the power transmission output with the GP range (5W) before the device authentication as the target value.

[0090] TX uses an analog Ping to wait for an object to be placed (S401, F1001). As a result of placing RX (F1002), a change occurs in the analog Ping (F1003), whereby TX detects that an object has been placed (F1004). According to the subsequent digital Ping, RX detects that its own device is placed on TX (S701, F1005, F1006). According to the response to the digital Ping, TX detects that the object placed on it is RX. Subsequently, using the communication in the configuration phase, TX obtains identification information and capability information from RX (S402, S702, F1007). Next, TX and RX communicate in the negotiation phase (S403, S703, F1008). At this point, device authentication is unsuccessful, so GP is determined to be 5W in this negotiation.

[0091] Subsequently, TX and RX start communication in the calibration phase (S404, S704). In the communication in the calibration phase, TX receives the first calibration reference value information indicating that the received power is 500mW from RX (F1009). Then, for example, as a result of judging that the power transmission state of TX itself is stable, TX determines to accept the first calibration reference value information and transmits ACK (F1010). Next, TX receives a power transmission output change indication (F1011) indicating an increase in the power transmission output from RX, and increases the power transmission output according to the indication (F1012). After that, TX receives the second calibration reference value information (F1013) indicating that the received power is 5W from RX. For example, as a result of judging that the power transmission state of TX itself is stable, TX determines to accept the second calibration reference value information and transmits ACK (F1015). In addition, TX calculates an estimated value of power loss based on the first calibration reference value information and the second calibration reference value information (F1014). By transmitting ACK in F1015, the power transmission phase begins (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, TX and RX re-execute the communication in the negotiation phase and redetermine the GP (S407, S707, F1017). Here, it is assumed that the GP is redetermined to 15W. After the GP is redetermined, TX and RX start the power transmission control process and the power reception control process, respectively (S408, S708).

[0092] After starting the power transmission control process, TX starts a timer until the calculation of the estimated value of the power loss is completed (S501, F1018). If a power transmission output change instruction indicating an increase in the power transmission output is received from RX, TX increases the power transmission output according to the instruction (S503, S802, S803, F1019, F1020). Subsequently, TX receives reception power information indicating that the reception power is 15W from RX (S808, F1021), and transmits an ACK for the reception power information (S505, F1022). If a power transmission output change instruction indicating that the power transmission output is not changed is received from RX (S804, F1023), TX complies with the instruction and does not change the power transmission output. Afterwards, TX uses, for example, a predetermined time that has passed since the start of the timer without receiving the enhanced calibration reference value information as a trigger to determine that a timeout has occurred, and starts a timeout process (S512, F1024). After starting the timeout process, if reception power information indicating that the reception power is 15W is received from RX (S808, F1025), TX transmits NAK to reduce the reception power in RX to 5W as a target value (S608, F1026). RX reduces power consumption (S810, F1027), and transmits a transmission output change instruction to TX indicating that the transmission output is reduced (S811, F1028). If the transmission output change instruction is received, TX reduces the transmission output according to the instruction (S604, F1029). Subsequently, if reception power information indicating that the reception power is 10W is received from RX (S808, F1030), since the reception power is higher than 5W as a target value, TX transmits NAK to cause RX to continue reducing the reception power (S608, F1031). RX reduces power consumption (S810, F1032), and transmits a power output change instruction (S811, F1033) to TX to indicate that the power output should be reduced. If the power output change instruction is received, TX reduces the power output according to the instruction (S604, F1034). After that, if the reception power information indicating that the reception power is 5W is received (S808, F1035), since the reception power is greater than or equal to 5W as the target value, TX transmits ACK to RX and continues to transmit power with the output (S607, F1036).

[0093] According to the above operation, if the estimated value of the power loss cannot be calculated after the fast charging with a relatively high transmission output is started, TX reduces the transmission output to the output range before the fast charging starts. This makes it possible to continue to use the transmission and reception of power with an appropriate transmission output while assuming the possibility of misdetection or detection failure of foreign objects. As a result of RX periodically transmitting enhanced calibration reference value information in the increase phase 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 increased or reduced received power can be accurately estimated, thereby preventing misdetection of foreign objects and failure to detect the presence of foreign objects. In the increase phase or decrease phase of the transmission output, if TX cannot obtain the enhanced calibration reference value information within a certain period of time, it is determined that a timeout has occurred, and TX does not increase (or reduce) the transmission output. This makes it possible to prevent the transmission and reception of power with power that may reduce the accuracy of foreign object detection.

[0094] <Processing Example 2>

[0095] Next, refer to Fig.11A and Fig. 11B To illustrate the second processing example. In this processing example, unlike processing example 1, in the event of a timeout, TX uses the received power represented by the valid enhanced calibration reference value information obtained immediately before as a target value to reduce the transmission output. Here, it is assumed that: after the GP is determined, when the received power in RX changes from 5W to 10W, TX receives enhanced calibration reference value information indicating that the received power of RX is 10W, calculates the estimated value of power loss, and transmits ACK. In this case, TX uses the transmission of ACK as a trigger to reset the timer and starts the timer again. Assume that: afterwards, the received power in RX changes from 10W to 15W, but TX cannot receive the enhanced calibration reference value information within a predetermined time. In this case, TX uses 10W (which is the received power represented by the last valid enhanced calibration reference value information obtained) as a target value to reduce the transmission output.

[0096] The processing operations in F1101 to F1120 are Fig. 10A and Fig. 10B The processing operations in F1001 to F1020 in FIG. 1004 are the same. Therefore, the description of these processing operations is omitted.

[0097] In F1121, RX transmits reception power information indicating that the reception power is 7W to TX (S808). If the reception power information is received, since no timeout occurs at this time, TX transmits ACK (S505, F1122). Since the reception power does not reach GP, RX then transmits a transmission output change instruction to TX to instruct to increase the transmission output (S802, S803, F1123). If the transmission output change instruction is received, TX increases the transmission output according to the instruction (S503, F1124).

[0098] After that, RX transmits enhanced calibration reference value information to TX in response to the occurrence of the transmission timing of the enhanced calibration reference value information (S806, F1125). Here, the enhanced calibration reference value information indicates that the received power in RX is 10 W. If the enhanced calibration reference value information is received, TX determines to accept the calibration reference value information, for example, as a result of judging that its own power transmission state is stable, calculates the estimated value of power loss (S508, F1126), and transmits ACK (S509, F1127).

[0099] After transmitting ACK, TX resets the timer and starts the timer again (S513, S501, F1128, F1129). After that, RX transmits reception power information indicating that the reception power is 13W to TX (S808, F1130). If the reception power information is received before the timer expires, TX transmits ACK (S505, F1131). After that, TX uses the predetermined time that has passed since the timer was started in F1129 without receiving the enhanced calibration reference value information as a trigger, determines that a timeout has occurred, and starts timeout processing (S512, F1132).

[0100] Since the received power does not reach the GP, RX then transmits a transmission output change instruction to TX indicating an increase in the transmission output (S802, S803, F1133). TX receives the transmission output change instruction, but does not follow the instruction because a timeout has occurred, and does not change the transmission output (S603, F1134). After that, RX transmits reception power information indicating that the received power is 13W to TX (S808, F1135). If the reception power information is received, since the timeout process has started, TX transmits NAK to RX so that RX reduces the reception power to 10W as the target value (S608, F1136). If NAK is received, RX reduces power consumption (S810, F1137), and transmits a transmission output change instruction to TX indicating a reduction in the transmission output (S811, F1138). If the transmission output change instruction is received, TX reduces the transmission output according to the instruction (S604, F1139). After that, RX transmits reception power information indicating that the reception power has been reduced to 10W as a result of the reduction in transmission output to TX (S808, F1140). If reception power information indicating that the reception power is 10W is received, since the reception power has been reduced to 10W or less as the target value, TX transmits ACK (S607, F1041). Then, TX continues to transmit power while maintaining the transmission output.

[0101] According to the above operation, if the estimated value of power loss cannot be calculated after the fast charging with a relatively high transmission output is started, TX reduces the transmission output so that the received power for which the estimated value of power loss has been calculated can be obtained. This makes it possible to continue the transmission and reception of power using the appropriate transmission output while assuming the possibility of false detection or detection failure of foreign objects. As a result of RX regularly transmitting enhanced calibration reference value information in the increase phase 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 increased or reduced received power can be accurately estimated, thereby preventing false detection of foreign objects and failure to detect the presence of foreign objects. If TX cannot obtain the enhanced calibration reference value information within a certain period of time in the increase phase or decrease phase of the transmission output, it is determined that a timeout has occurred, and TX does not increase (or reduce) the transmission output. This makes it possible to prevent the transmission and reception of power that may reduce the accuracy of foreign object detection.

[0102] TX can start the above-mentioned timer at a timing before re-performing device authentication and negotiation. For example, TX can use the completion of calibration as a result of 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 the calibration is completed using a received power (for example, 3W) smaller than 5W (which is the GP determined by the power receiving device that failed to successfully authenticate the device), TX can start the timer. Then, if TX fails to receive the enhanced calibration reference value information (for example, which indicates 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 transmission output. By reducing the transmission output to the output used when the calibration is completed before the start of fast charging in this way, it is possible to continue to transmit and receive power with an appropriate output in a state where the transmission output is small and therefore the error variation tends to be large.

[0103] TX can use the change in the received power to be greater than or equal to the threshold as a trigger to start the above timer. That is, TX can be configured not to execute the timer before the change in the received power becomes greater than or equal to the threshold. Figure 5 or Fig. 6A and Figure 6BThe processing operation associated with the timeout shown. For example, TX may start a timer using the reception of the following reception power information or calibration reference value information as a trigger, or using the transmission of a response to the reception power information or calibration reference value information as a trigger, wherein the reception power information or calibration reference value information indicates that the reception power change relative to the reception power immediately after the calibration is completed is greater than or equal to the threshold. TX may start a timer using the reception of the following reception power information or calibration reference value information as a trigger, or using the transmission of a response to the reception power information or calibration reference value information as a trigger, wherein the reception power information or calibration reference value information indicates that the reception power change relative to the reception power when the valid enhanced calibration reference value information is obtained is greater than or equal to the threshold. TX may start a timer using the reception of the following reception power information or calibration reference value information as a trigger, or using the transmission of a response to the reception power information or calibration reference value information as a trigger, wherein the reception power information or calibration reference value information indicates that the reception power change relative to any reception power in the reception power represented by the valid calibration reference value information is greater than or equal to the threshold. Therefore, in the case where the change in the received power calculated relative to the estimated value of the power loss is not significant and therefore the accuracy of the foreign object detection is considered to be sufficiently ensured, the occurrence of unnecessary timeouts and unnecessary changes in the power transmission output can be suppressed. As the threshold value of the amount of change in the received power, a predetermined fixed value may be used, or a value determined between TX and RX by any communication performed before the start of the power transmission phase may be used. TX may be configured not to perform the enhanced calibration reference value information until the amount of change in the received power becomes greater than or equal to the threshold value after the effective enhanced calibration reference value information is obtained. Figure 5 or Fig. 6A and Figure 6B The processing actions associated with the timeout are shown.

[0104] TX can use the change in the power output becoming greater than or equal to the threshold as a trigger to start the above timer. That is, TX can be configured not to execute the timer before the change in the power output becomes greater than or equal to the threshold. Figure 5 or Fig. 6A and Figure 6BThe processing operation associated with the timeout shown. For example, TX can use the change amount of the transmission output relative to the transmission output immediately after the calibration is completed to become greater than or equal to the threshold as a trigger, or use the change amount of the transmission output relative to the transmission output when the valid calibration reference value information is obtained to become greater than or equal to the threshold as a trigger to start the timer. In the example, when the value that increases by 1 when the transmission output increases according to the above-mentioned transmission output change indication and decreases by 1 when the transmission output decreases according to the 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 transmission output will change according to the transmission output change indication is specified, TX can accumulate and add the specified value, and when the value reaches a predetermined positive value or a predetermined negative value, the timer can be started. TX can monitor its own transmission output, and can use the change amount reaching a predetermined value as a trigger to start the timer. Therefore, under the assumption that the change in the transmission output after the estimated value of the power loss is calculated and the change in the received power are not significant, the occurrence of unnecessary timeouts and unnecessary changes in the transmission output can be suppressed. The TX may be configured not to execute the command until the change in the power output after obtaining the valid enhanced calibration reference value information becomes greater than or equal to the threshold. Figure 5 or Fig. 6A and Figure 6B The processing actions associated with the timeout are shown.

[0105] TX can use the receipt of enhanced calibration reference value information after calculating the estimated value of power loss as a trigger to start the above timer. That is, TX can be configured not to perform the above timer before receiving the enhanced calibration reference value information. Figure 5 or Fig. 6A and Figure 6B The processing operation associated with the timeout is shown. Therefore, the timeout can be set only when the 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.

[0106] When power transmission and reception are performed outside the range of the received reference value of the received reception power, enhanced calibration reference value information can be transmitted. In this case, the expression "falling outside the range of the 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.

[0107] When the GP is increased as a result of device authentication (Authentication) using an electronic certificate for a power transmitting device or device authentication (Authentication) using an electronic certificate for a power receiving device, the enhanced calibration reference value information may be transmitted.

[0108] For example, in the case where power is transmitted and received for a long period of time, the accuracy of the foreign object detection process using the calibration reference value obtained in the calibration phase may be reduced due to the influence of heat, etc. For this reason, if a certain amount of time has passed after the calibration reference value was obtained, the calibration reference value can be obtained as enhanced calibration reference value information. For example, TX can request enhanced calibration reference value information from RX.

[0109] In the case where the reception power in the power receiving apparatus changes to a value exceeding a predetermined value, enhanced calibration reference value information may be transmitted.

[0110] If the predetermined conditions are met, TX does not need to start the above timer. That is, TX can be configured not to execute the timer during the period when the predetermined conditions are not met. Figure 5 or Fig. 6A and Figure 6B The processing operation associated with the timeout shown. TX can be configured not to start the timer, for example, when power is transmitted and received using a received power closer to the received power represented by the valid calibration reference value information obtained in the past, or when power is transmitted and received using a received power within the range of the estimated value calculated using a plurality of calibration reference value information. TX can be configured not to start the timer when the number of times the estimated value is calculated using the valid calibration reference value information obtained in the past becomes greater than or equal to a predetermined number of times. Therefore, while the accuracy of foreign object detection is sufficiently ensured, the occurrence of unnecessary timeouts and unnecessary changes in the power transmission output can be suppressed.

[0111] 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 power loss has been calculated. However, a received power outside the above range and having a difference of less than a threshold value from the received power for which the estimated value of power loss has been calculated may be used as the target value. This makes it possible to continue charging as fast as possible without significantly affecting the accuracy of foreign object detection using the calculated estimated value.

[0112] In the above example, after the timeout occurs, TX changes the transmission output so that the received power has the target value. However, negotiation can be performed again between TX and RX, and GP can be changed to the target value. At this time, negotiation is performed so 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 RX can receive can be maintained at the target value or less, thereby making it possible to continue charging while suppressing the decrease in the accuracy of foreign object detection.

[0113] After the timeout occurs, TX can determine that some problem has occurred in the charging process and stop the power transmission. This makes it possible to suppress the occurrence of problems caused by undetected foreign objects or erroneous operation, etc. After stopping the power transmission, TX can return the processing to the selection stage in S401. Therefore, if it is difficult to continue the power transmission due to, for example, the position shift of RX, the predetermined processing for starting charging can be re-executed, thereby appropriately restarting the charging. If an abnormality is detected, TX can limit the power transmission to reduce the power to be transmitted.

[0114] In the above example, after a timeout occurs, TX transmits a NAK to RX for the received power information to change the transmission output so that the received power has a target value. At this time, TX can transmit a response including additional information. For example, TX can include a notification to change the transmission output, a reason for changing the transmission output, a target value of the received power, a criterion for judging the timeout, and a request to transmit additional calibration reference value information in the NAK to be transmitted. This information can be transmitted using a separate response signal / message different from the NAK. All 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 RX to use, for example, the display unit 207 to notify the user via a display, etc. that fast charging is restricted, thereby improving user convenience. In addition, RX can use the reception of additional information as a trigger to transmit additional calibration reference value information, so that changes in the transmission output in TX can be avoided and fast charging can continue.

[0115] After the timeout occurs, TX can use the display unit 307 to ask the user whether to continue fast charging, and can judge whether to change the transmission output according to 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, TX can be configured to transmit ACK to the received power information without changing the transmission output. This processing can be performed using the display unit 207 and the operation unit 208 of RX. For example, RX can be configured to start an inquiry to the user using the reception of the above-mentioned additional information as a trigger, and can be configured not to transmit a transmission output change instruction indicating a reduction in the transmission output when an instruction to continue fast charging is given within a predetermined time. Therefore, in the case where the user can judge that no foreign matter or the like has been incorporated, unnecessary changes in the transmission output can be suppressed, thereby continuing fast charging.

[0116] In the above example, when increasing the received power in RX, if the calibration reference value information is not received within a predetermined time or longer, the transmission output is reduced (or not increased). The same process can also be performed when reducing the received power in 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 TX can increase the transmission output so that the received power in RX increases. For example, TX can use the maximum received power of all received powers represented by the valid calibration reference value information obtained in the past as the target value. In this case, RX transmits a transmission output change indication to TX indicating an increase in the transmission output. This makes it possible to continue charging as fast as possible using the received power that can accurately detect foreign matter.

[0117] In the above example, TX calculates an estimated value of power loss. However, the present invention is not limited to this. That is, TX only needs to obtain information for associating the transmission output with the received power in RX that can be obtained with the transmission output. For example, TX only needs to obtain a combination of the received power Pr1 of the first calibration reference value and the transmission output Pt1 at this time, and a 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 transmission power, and if the absolute value of the difference exceeds a predetermined value, the presence of foreign matter can be detected.

[0118] Other embodiments

[0119] The present invention can be implemented by the following process: a program for implementing one or more functions of the above-mentioned embodiment is supplied to a system or device via a network or storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be implemented by a circuit (e.g., ASIC) for implementing one or more functions.

[0120] The present invention is not limited to the above-described embodiments, and various changes and modifications can be made within the spirit and scope of the present invention. Therefore, in order to inform the public of the scope of the present invention, the following claims are added.

Claims

1. A power transmission device, comprising: A power transmission component, used for wirelessly transmitting power to a powered device; A communication component, used for communicating with the powered device; as well as a processing means for performing a detection process for detecting a foreign object using the power loss in the power transmission stage, wherein the communication section receives first information from the powered device, the first information indicating calibration information and including information related to the first received power, and the first information is used to obtain the power loss, wherein, after the communication component receives the first information, the communication component receives second information, the second information indicating calibration information and including information related to the second received power, wherein, after the communication component receives the second information, the communication component receives third information including information related to third received power, and Wherein, when the difference between the second received power and the third received power is greater than a threshold value and a predetermined time has passed since the timing when the communication component receives the third information or the timing when a response to the third information is transmitted to the power receiving device without receiving fourth information, the power transmission component performs specific control for limiting power transmission, wherein the fourth information represents calibration information and includes information related to the fourth received power.

2. The power transmission device according to claim 1, in, In the specific control, the power transmitting section reduces the transmitted electric power until the reception electric power of the power receiving apparatus is reduced to the second reception electric power.

3. The power transmission device according to claim 1, further comprising: an execution component, configured to execute authentication with the powered device, Here, in the specific control, the power transmitting means reduces the transmitted power until the reception power of the power receiving device is reduced to the reception power to be obtained in the device for which authentication has not yet succeeded.

4. The power transmission device according to claim 1, in, In the specific control, the power transmission section reduces the transmitted power by causing the communication section to transmit a negative acknowledgement, thereby controlling the power receiving device to transmit control error information for reducing the transmitted power.

5. The power transmission device according to claim 1, in, During the specific control, even when control error information for increasing the transmitted power is received from the power receiving apparatus using the communication means, the power transmitting means prevents the increased power transmitted using the power transmitting means.

6. The power transmission device according to claim 1, in, In the specific control, the power transmission means negotiates the power via the communication means.

7. The power transmission device according to claim 1, in, In the specific control, the power transmitting means stops power transmission performed by the power transmitting means. 8 . A computer-readable storage medium storing a program for causing a computer to execute the processing performed by the power transmission device according to claim 1 .

9. A power transmission device comprising: A power transmission component, used for wirelessly transmitting power to a powered device; A communication component, used for communicating with the powered device; as well as a processing means for performing a detection process for detecting a foreign object using the power loss in the power transmission stage, wherein the communication section receives first information from the powered device, the first information indicating calibration information and including information related to the first received power, and the first information is used to obtain the power loss, wherein, after the communication component receives the first information, the communication component receives second information, the second information indicating calibration information and including information related to the second received power, wherein the communication component receives control error information from the powered device, and Wherein, when a predetermined time has passed since the timing when the power change amount of the transmitted power caused by the control error information relative to the time when the communication component receives the second information is greater than or equal to a threshold or since the timing when a response to the control error information is transmitted to the power receiving device, and third information has not been received, the power transmitting component performs specific control for limiting power transmission, and the third information represents calibration information and includes information related to the third received power.

10. The power transmission device according to claim 9, in, In the specific control, the power transmitting section reduces the transmitted electric power until the reception electric power of the power receiving apparatus is reduced to the second reception electric power.

11. The power transmission device according to claim 9, further comprising: an execution component, configured to execute authentication with the powered device, Here, in the specific control, the power transmitting means reduces the transmitted power until the reception power of the power receiving device is reduced to the reception power to be obtained in the device for which authentication has not yet succeeded.

12. The power transmission device according to claim 9, in, In the specific control, the power transmission section reduces the transmitted power by causing the communication section to transmit a negative acknowledgement, thereby controlling the power receiving device to transmit control error information for reducing the transmitted power.

13. The power transmission device according to claim 9, in, During the specific control, even when control error information for increasing the transmitted power is received from the power receiving apparatus using the communication means, the power transmitting means prevents the increased power transmitted using the power transmitting means.

14. The power transmission device according to claim 9, in, In the specific control, the power transmission means negotiates the power via the communication means.

15. The power transmission device according to claim 9, in, In the specific control, the power transmitting means stops power transmission performed by the power transmitting means. 16 . A computer-readable storage medium storing a program for causing a computer to execute the processing performed by the power transmission device according to claim 9 .

17. A method for transmitting electricity, which is performed using an electricity transmission device, the electricity transmission device comprising: A power transmission component, used for wirelessly transmitting power to a powered device; and a communication component for communicating with the powered device, the power transmission method comprising: In the power transmission phase, a detection process for detecting foreign matter is performed using the power loss; receiving first information from the powered device, the first information indicating calibration information and including information related to first received power, and the first information being used to obtain the power loss; After receiving the first information, receiving second information, the second information indicating calibration information and including information related to the second received power; After receiving the second information, receiving third information including information related to third reception power; and When the difference between the second received power and the third received power is greater than a threshold value and a predetermined time has passed since the timing when the third information is received or the timing when a response to the third information is transmitted to the power receiving device without receiving fourth information, specific control for limiting power transmission is performed, wherein the fourth information indicates calibration information and includes information related to the fourth received power.

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