Power receiving device and method performed by power receiving device

Abstract

The invention provides a power receiving device and a method performed by the power receiving device. The power transmission device (101) performs a detection process for detecting an object different from the power reception device (102), and performs a process for a parameter used in the detection process on the basis of a voltage change in the voltage applied to the power transmission unit (203).

Description

[0001] (This application is a divisional application of an application with a filing date of May 10, 2021, application number 202180037093.3, and invention name “Power transmission device, power receiving device, control method and program”.) Technical Field

[0002] The present invention relates to a power transmitting device, a power receiving device, a control method, and a program associated with wireless power transmission. Background Art

[0003] In recent years, technologies used in wireless power transmission systems such as wireless charging systems have been widely developed. Patent document 1 describes a power transmitting device and a power receiving device that conform to a standard (hereinafter referred to as the "WPC standard") developed by the Wireless Power Consortium (WPC), an organization for standardizing wireless charging. In addition, Patent document 1 describes a calibration process defined by the WPC standard, which is intended to improve the detection accuracy of conductive objects (foreign objects) such as metal sheets.

[0004] In the calibration process, the received power in the power receiving device and the power loss at that time are acquired in each of two different states. The power loss is derived as the difference between the transmitted power in the power transmitting device and the received power in the power receiving device. Then, by using each pair of the received power and the power loss in these two states as a parameter, the expected power loss is derived relative to the received power notified from the power receiving device in the wireless power transmission. In the case where the difference between the actual power loss and the expected power loss exceeds a predetermined value, it can be determined that there has been power loss due to foreign matter, that is, there is foreign matter.

[0005] On the other hand, Universal Serial Bus Power Delivery (USB PD) is becoming popular as a standard for supplying power intended, for example, to quickly charge a battery in a wired manner. According to USB PD, control is performed so that if the power supplied to a load increases, the voltage output to the load increases accordingly. In this way, even if the supplied power increases, the current remains low; therefore, loss and heat generation in the circuit are suppressed, and power can be supplied to the load while maintaining high efficiency.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-070074 Summary of the invention

[0009] Problem that the invention aims to solve

[0010] In a case where the input voltage to a power transmission unit including a power transmission coil is changed in a power transmission device for wireless power transmission to change the transmitted power, the power loss of the power receiving device in each state changes before and after the input voltage is changed. Therefore, if the detection of foreign matter is attempted in the state after the input voltage is changed while using a pair of the received power and the power loss acquired in the state before the input voltage to the power transmission unit is changed as a parameter, the detection accuracy of the foreign matter decreases.

[0011] The present invention provides a technique for suppressing a decrease in the accuracy of a detection process for detecting an object different from a power receiving device even when an input voltage to a power transmitting unit in a power transmitting device has changed.

[0012] Solutions for solving problems

[0013] A power transmission device according to one aspect of the present invention has the following configuration. Specifically, the power transmission device includes: a power transmission component for wirelessly transmitting power to a power receiving device; an application component for applying power used for power transmission to the power transmission component; and a processing component for performing a detection process for detecting an object different from the power receiving device, wherein the processing component performs a process on a parameter used in the detection process based on a voltage change of a voltage applied to the power transmission component.

[0014] Effects of the Invention

[0015] According to the present invention, even when the input voltage to the power transmission unit in the power transmitting device has changed, it is possible to suppress a decrease in the accuracy of the detection process for detecting an object different from the power receiving device.

[0016] Other features and advantageous effects of the present invention will become apparent from the following description provided with reference to the accompanying drawings. Note that in the accompanying drawings, the same or similar components are given the same reference numerals. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention.

[0018] Figure 1 is a diagram showing an exemplary structure of a wireless charging system.

[0019] Figure 2 is a block diagram showing an exemplary structure of a power transmitting device according to the first embodiment.

[0020] Figure 3 is a block diagram showing an exemplary structure of a power receiving apparatus according to the first embodiment.

[0021] Figure 4A is a flowchart showing an exemplary flow of processing by the power transmitting apparatus according to the first embodiment.

[0022] Figure 4B is a flowchart showing an exemplary flow of processing by the power transmitting apparatus according to the first embodiment.

[0023] Figure 5A is a flowchart showing an exemplary flow of processing by the power receiving apparatus according to the first embodiment.

[0024] Figure 5B is a flowchart showing an exemplary flow of processing by the power receiving apparatus according to the first embodiment.

[0025] Figure 6 : is a diagram showing an exemplary flow of processing performed in the wireless charging system according to the first embodiment.

[0026] Figure 7 7 is a diagram showing a communication sequence (7a) in the I&C phase, a communication sequence (7b) in the negotiation phase, and a communication sequence (7c) in the calibration phase.

[0027] Figure 8 : is a diagram showing an example of the contents of parameters used in the foreign matter detection process.

[0028] Fig. 9 It is a diagram for explaining linear complementarity in foreign matter detection processing.

[0029] Fig.10 : are diagrams showing an example of a table describing the relationship between GP and an output voltage to a power transmission unit according to the first embodiment and an example of a table describing the relationship between GP and an input voltage to a charging unit according to the first embodiment.

[0030] Fig.11 is a diagram showing an example of a table describing the relationship between GP and an input voltage to a charging unit according to the second embodiment.

[0031] Fig.12 is a diagram showing an exemplary flow of processing performed in the wireless charging system according to the second embodiment.

[0032] Fig.13A is a flowchart showing an exemplary flow of processing by the power transmitting apparatus according to the third embodiment.

[0033] Fig. 13B is a flowchart showing an exemplary flow of processing by the power transmitting apparatus according to the third embodiment.

[0034] Fig.14A is a flowchart showing an exemplary flow of processing by a power receiving apparatus according to the third embodiment.

[0035] Fig. 14B is a flowchart showing an exemplary flow of processing by a power receiving apparatus according to the third embodiment. DETAILED DESCRIPTION

[0036] Embodiments of the present invention are described below with reference to the accompanying drawings. Note that the following embodiments are merely examples for explaining the technical idea of ​​the present invention, and are not intended to limit the present invention to the structures and methods described in the embodiments.

[0037] <First Embodiment>

[0038] (System Structure)

[0039] Figure 1 An exemplary structure of a wireless charging system (wireless power transmission system) according to the present embodiment is shown. The present system is configured to include a power transmitting device 101 and a power receiving device 102. Hereinafter, the power transmitting device may be referred to as TX, and the power receiving device may be referred to as RX. TX 101 is an electronic device that wirelessly transmits power to RX 102 placed on a charging stand 103. RX 102 is an electronic device that receives power wirelessly transmitted from TX 101 and charges an internal battery. The following description is provided using an exemplary case where RX 102 is placed on a charging stand 103. Note that it is sufficient for RX 102 to be present in a range where TX 101 can transmit power during power transmission from TX 101 to RX 102, and RX 102 does not necessarily need to be placed on the charging stand 103.

[0040] Note also that TX 101 and RX 102 may each have a function of executing applications other than wireless charging. An example of RX 102 is a mobile information device that operates with the aid of a rechargeable battery, such as a laptop PC (personal computer), a tablet PC, and a smart phone. In addition, an example of TX 101 is an accessory device for charging the mobile information device. Note that TX 101 and RX 102 may be storage devices such as hard disk devices and memory devices, and may be information processing devices such as personal computers (PCs). In addition, TX 101 and RX 102 may be, for example, image input devices such as imaging devices (e.g., cameras or video cameras) and scanners, or may be image output devices such as printers, copiers, or projectors. In addition, TX 101 may be a mobile information device. In this case, RX 102 may be another mobile information device, or may be a wireless headset. In addition, RX 102 may be a car. In addition, TX 101 may be a charger installed in a console inside a car, for example.

[0041] In addition, in the present invention, a foreign object is a conductive object such as a metal piece. However, among objects that are essential components for the RX 102 and the product in which the RX 102 is built, or for the TX 101 and the product in which the TX 101 is built, an object that has the possibility of generating heat in an unexpected manner when receiving power wirelessly transmitted from the power transmission coil is not regarded as a foreign object. Note that in the present invention, a foreign object may be a power receiving device different from the RX 102 to which power is transmitted.

[0042] In addition, although one TX 101 and one RX 102 are shown in the wireless charging system of the present embodiment, the present invention is not limited thereto. The present invention is also applicable to a configuration in which, for example, a plurality of RX 102 receive power transmitted from one TX 101 or separate TX 101s.

[0043] This system performs wireless power transmission using an electromagnetic induction method used for wireless charging based on the Wireless Power Consortium standard (hereinafter referred to as the WPC standard). That is, TX 101 and RX 102 perform wireless power transmission for wireless charging based on the WPC standard between the power transmission coil of TX 101 and the power receiving coil of RX 102. Note that the wireless power transmission method (non-contact power transmission method) applied to this system is not limited to the method defined by the WPC standard, and may be other methods such as an electromagnetic induction method, a magnetic resonance method, an electric field resonance method, a microwave method, and a method using a laser, etc. In addition, although it is assumed in this embodiment that wireless power transmission is used in wireless charging, wireless power transmission may be performed for purposes other than wireless charging.

[0044] According to the WPC standard, the amount of power guaranteed when the RX 102 receives power from the TX 101 is defined by a value called guaranteed power (hereinafter referred to as "GP"). GP represents a power value guaranteed for output to a load (e.g., a charging circuit, etc.) of the RX 102 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 the TX 101 and the RX 102. For example, when the GP is 5 watts, even if the power transmission efficiency decreases due to a change in the positional relationship between the power receiving coil and the power transmitting coil, the TX 101 controls the power transmission so that 5 watts can be output to the load inside the RX 102.

[0045] According to the present embodiment, the TX 101 and the RX 102 perform communication for power transmission / reception control based on the WPC standard. The WPC standard defines a plurality of stages including a power transmission stage for performing power transmission and a stage before performing power transmission, and communication for power transmission / reception control is performed in each stage. The stage before power transmission includes a selection stage, a Ping stage, an identification and configuration stage, a negotiation stage, and a calibration stage. Note that the identification and configuration stage is hereinafter referred to as the I&C stage.

[0046] In the selection phase, TX 101 sends an analog Ping in an intermittent and repeated manner, and detects that an object is placed on the charging table 103 (for example, RX 102 or a conductor sheet, etc. is placed on the charging table 103). The analog Ping is a detection signal for detecting the presence of an object. TX 101 sends an analog Ping by applying a voltage or current to the power transmission coil. When the state where no object is placed on the charging table 103 changes to the state where an object is placed on the charging table 103, the voltage or current applied to the power transmission coil changes. TX 101 detects at least one of the voltage value and the current value of the power transmission coil when sending the analog Ping, and when the voltage value drops below a certain threshold or when the current value exceeds a certain threshold, it is determined that an object exists and transitions to the Ping phase.

[0047] In the Ping phase, TX 101 transmits a digital Ping which is higher in power than the analog Ping. The power of the digital Ping is enough to activate the control unit of the RX 102 placed on the charging station 103. The RX 102 notifies the TX 101 of the magnitude of the power receiving voltage. In the present embodiment, the RX 102 transmits a signal strength packet (hereinafter referred to as an "SS packet") to the TX 101. The TX 101 recognizes that the object detected in the selection phase is the RX 102 by receiving a response (SS packet) from the RX 102 which has received the digital Ping transmitted by itself. Upon receiving the notification regarding the power receiving voltage value, the TX 101 transitions to the I&C phase.

[0048] In the I&C phase, TX 101 identifies RX 102 and acquires device configuration information (capability information) from RX 102. Therefore, RX 102 sends an identification packet (ID packet) and a configuration packet to TX 101. The ID packet includes the identification information of RX 102, and the configuration packet includes the device configuration information (capability information) of RX 102. TX 101, which has received the ID packet and the configuration packet, responds via an acknowledgment (ACK). Then, the I&C phase ends. In the subsequent negotiation phase, the value of GP is determined based on the value of GP requested by RX 102 and the power transmission capability of TX 101.

[0049] In the calibration phase, the RX 102 notifies the TX 101 of the received power using the received power packet. At this time, the RX 102 provides notifications related to at least two different received powers. For example, the RX 102 provides notifications related to two received powers (i.e., the received power in the state where no load is connected and the received power in the state where a load is connected and power close to the GP value is received). At the same time, when the TX 101 receives each notification related to these received powers, it obtains its own transmitted power, derives the power loss based on the difference between the transmitted power and the received power, and stores the power loss in association with the received power. In the subsequent power transmission phase, the TX 101 performs a foreign object detection process for detecting foreign objects other than the power receiving device using the pair of received power and power loss stored in the above-described manner as parameters.

[0050] Now, a method for performing a foreign object detection process in the TX 101 using two pairs of received power and power loss as parameters will be described. The TX 101 stores the two pairs of received power and power loss via communication in the calibration phase. Assume that in these two pairs, one pair is "received power = RP1, power loss = PL1" and the other pair is "received power = RP2, power loss = PL2".

[0051] When performing the foreign object detection process in the power transmission phase, the TX 101 first obtains the current received power = P from the RX 102 received . Subsequently, the TX 101 derives the expected value PL of the power loss at this time by linear interpolation between the two points (RP1, PL1) and (RP2, PL2) cal . Note that it is assumed that RP1 < RP2. Specifically, the expected value can be derived using the following Expression 1.

[0052] [Expression 1]

[0053] PL cal =

[0054] (PL2 - PL1) / (RP2 - RP1)·(P received - RP1) + PL1

[0055] Here, using the following Expression 2, the current power loss PL can be derived based on the current transmitted power P in the TX 101 transmitted and the received power = P notified from the RX102 received . If the current power loss PL exceeds a predetermined value compared to the expected value PL cal , the TX 101 determines that the power loss has increased as a result of power consumption caused by a foreign object value, that is, a foreign object has been detected.

[0056] [Expression 2]

[0057] PL=P transmitted -P received

[0058] According to the aforementioned method, the expected value of the current power loss is derived by linear complementation while using the value of the power loss acquired in advance as a parameter. This is expressed as calibration of the power loss. Note that instead of the power loss of RX 102, the object of calibration may be, for example, the received power of RX 102, or may be the transmitted power of TX 101. In addition, the method of deriving the expected value of the power loss (that is, the method of performing the calibration) is not limited to linear complementation, and may be, for example, nonlinear complementation using a power series or the like. In addition, three or more pairs of information (for example, pairs of received power and transmitted power) may be used as parameters. An example of using three or more pairs of information as parameters is the linear complementation of the broken lines connecting (RP1, PL1) and (RP2, PL2) and (RP2, PL2) and (RP3, PL3). Here, (RP3, PL3) is information on the third pair of received power and power loss, and RP2 <RP3。

[0059] In the power transmission phase, control is performed for starting and continuing power transmission, stopping power transmission due to detection of foreign objects or a fully charged state, etc. In the present embodiment, in the power transmission phase, processing for changing GP, changing the power transmission voltage of the power transmitting device, changing the output voltage to the load of the power receiving device, and processing for requesting re-acquisition and addition of parameters used for foreign object detection processing are further performed. The details of this processing will be described later.

[0060] TX 101 and RX 102 perform the aforementioned communication for power transmission / reception control based on the WPC standard by superimposing a signal on the transmission power using the same antenna (coil) as used for wireless power transmission. Note that TX 101 and RX 102 may perform communication for power transmission / reception control using an antenna (coil) different from the antenna (coil) used for wireless power transmission. Examples of communication using an antenna (coil) different from the antenna (coil) used for wireless power transmission include Bluetooth compliant In addition, wireless LANs such as the IEEE 802.11 standard series (e.g., ), ZigBee, and NFC (Near Field Communication) etc. 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.

[0061] (Equipment Structure)

[0062] Subsequently, a description is given of the structure of the power transmitting device 101 (TX 101) and the power receiving device 102 (RX 102) according to the present embodiment. Note that the structure described below is only an example; a part (or all, depending on the situation) of the structure described can be replaced with other structures that implement other similar functions, or can be omitted, and further structures can be added to the structure described below. In addition, one block mentioned in the following description can be divided into multiple blocks, and multiple blocks can be integrated into one block.

[0063] Figure 2 1 is a block diagram showing an exemplary structure of the TX 101 according to the present embodiment. In one example, the TX 101 includes a control unit 201, a power supply unit 202, a power transmission unit 203, a placement detection unit 204, a power transmission coil 205, a communication unit 206, a notification unit 207, an operation unit 208, a memory 209, a timer 210, an input voltage setting unit 211, and a re-acquisition request unit 212.

[0064] The control unit 201 controls the entire TX 101 by executing a control program stored in, for example, the memory 209. That is, the control unit 201 controls Figure 2 The functional units shown. In addition, the control unit 201 performs control related to power transmission control in TX 101. The control unit 201 can also perform control for executing applications other than wireless power transmission. The control unit 201 is configured to include one or more processors such as a CPU and an MPU. Note that the control unit 201 can be configured to include hardware dedicated to a specific process (such as an application-specific integrated circuit (ASIC)), or an array circuit compiled to perform a predetermined process (such as an FPGA). The control unit 201 stores information to be stored during the execution of various types of processing in the memory 209. In addition, the control unit 201 can use a timer 210 to measure a time period.

[0065] The power supply unit 202 supplies power required for the control unit 201 to control the TX 101 and for power transmission and communication to the entire TX 101. The power supply unit 202 is, for example, a commercial power supply or a battery. The battery stores power supplied from the commercial power supply.

[0066] The power transmission unit 203 converts the DC or AC power input from the power supply unit 202 into AC frequency power of the frequency band used in wireless power transmission, and inputs the AC frequency power to the power transmission coil 205; as a result, an electromagnetic wave for receiving power at the RX 102 is generated. Note that the frequency of the AC power generated by the power transmission unit 203 is, for example, about several hundred kHz (for example, 110kHz to 205kHz). Based on the instruction from the control unit 201, the power transmission unit 203 inputs the AC frequency power to the power transmission coil 205 so that the power transmission coil 205 outputs an electromagnetic wave for transmitting power to the RX 102. In addition, the power transmission unit 203 controls the intensity of the electromagnetic wave to be output by adjusting one or both of the voltage (power transmission voltage) and the current (power transmission current) to be input to the power transmission coil 205. Increasing the power transmission voltage or the power transmission current enhances the intensity of the electromagnetic wave, while reducing the power transmission voltage or the power transmission current weakens the intensity of the electromagnetic wave. In addition, based on the instruction from the control unit 201, the power transmission unit 203 performs output control for the AC frequency power so that the power transmission from the power transmission coil 205 is started or stopped. In addition, the power transmission unit 203 notifies the control unit 201 of the current power transmission. In this way, the control unit 201 can know the current power transmission at any timing. Note that it is allowed to adopt a configuration in which an entity other than the power transmission unit 203 measures the power transmission and provides a notification to the control unit 201.

[0067] The placement detection unit 204 detects whether an object is placed on the charging table 103 based on the WPC standard. Specifically, the placement detection unit 204 detects whether an object is placed on the interface surface of the charging table 103. The placement detection unit 204 detects at least one of a voltage value and a current value of the power transmission coil 205 when, for example, the power transmission unit 303 transmits an analog Ping of the WPC standard via the power transmission coil 205. Note that the placement detection unit 204 can detect a change in impedance. Then, in the case where the voltage drops below a predetermined voltage value, or in the case where the current value exceeds a predetermined current value, the placement detection unit 204 can determine that the object is placed on the charging table 103. Note that the object is determined to be a power receiving device or other foreign matter based on whether there is a predetermined response from the RX 102 to the digital Ping that is subsequently transmitted by the communication unit 206. That is, in the case where the TX 101 receives a predetermined response, it is determined that the object is a power receiving device (RX 102); otherwise, it is determined that the object is an object different from the power receiving device.

[0068] The communication unit 206 performs the control communication based on the WPC standard described above with the RX 102. The communication unit 206 performs communication by modulating the electromagnetic wave output from the power transmission coil 205 and transmitting information to the RX 102. In addition, the communication unit 206 acquires the information transmitted by the RX 102 by demodulating the electromagnetic wave output from the power transmission coil 205 and modulated by the RX 102. That is, the communication unit 206 performs communication by superimposing on the electromagnetic wave transmitted from the power transmission coil 205.

[0069] The notification unit 207 notifies the user of information using, for example, any visual, auditory, or tactile method. The notification unit 207 notifies the user of, for example, the charging status of the TX 101 and the Figure 1 The power transmission-related status of the wireless power transmission system of TX 101 and RX 102 is shown. The notification unit 207 is configured to include, for example, a liquid crystal display, an LED, a speaker, a vibration generation circuit, and other notification means.

[0070] The operation unit 208 has an accepting function for accepting an operation performed by a user on the TX 101. The operation unit 208 is configured to include, for example, a button, a keyboard, a sound input device such as a microphone, a motion detection device such as an acceleration sensor and a gyroscope, or other input devices. Note that a device such as a touch screen in which the notification unit 207 and the operation unit 208 are integrated may be used.

[0071] The memory 209 stores various types of information such as identification information and capability information, and control programs, etc. Note that the memory 209 may store information acquired by a functional unit different from the control unit 201. The timer 210 measures time using, for example, an up-count timer for measuring a time period elapsed from a startup time and a down-count timer for counting down from a set time, etc. Under the control of the control unit 201, the input voltage setting unit 211 sets an input voltage for supplying power from the power supply unit 202 to the power transmission unit 203. The input voltage setting unit 211 includes a variable voltage unit.

[0072] Using the communication unit 206, the re-acquisition request unit 212 requests the RX 102 to re-acquire the parameters used for the foreign object detection process. The parameters used for the foreign object detection process represent one or more pairs of received power and power loss mentioned in the previous description of the calibration phase. Note that the re-acquisition request unit 212 may be configured to operate entirely or partially on a processor different from the processor of the control unit 201, and may be implemented by a program operating on the control unit 201. The function of the re-acquisition request unit 212 may be implemented by executing a program stored in, for example, the memory 209.

[0073] Here, the power supply unit 202 and the input voltage setting unit 211 may exist as other devices outside the TX 101. Examples of these external devices include a power adapter that provides power based on the USB PD standard. In this case, the control unit 201 may control the input voltage setting unit 211 via communication of the USB PD standard.

[0074] Figure 3 3 is a block diagram showing an exemplary structure of the RX 102 according to the present embodiment. The RX 102 includes a control unit 301, a battery 302, a power receiving unit 303, a placement detection unit 304, a power receiving coil 305, a communication unit 306, a notification unit 307, an operation unit 308, a memory 309, and a timer 310. The RX 102 also includes an output power setting unit 311, a re-acquisition instruction unit 312, and a charging unit 313.

[0075] The control unit 301 controls the entire RX 102 by executing a control program stored in, for example, the memory 309. That is, the control unit 301 controls Figure 3 The functional units shown. In addition, the control unit 301 performs control related to power reception control in RX 102. The control unit 301 can also perform control for executing applications other than wireless power transmission. The control unit 301 is configured to include one or more processors such as a CPU (Central Processing Unit) and an MPU (Micro Processing Unit). Note that the control unit 301 can be composed of hardware dedicated to specific processing, such as an application-specific integrated circuit (ASIC), etc. In addition, the control unit 301 can be configured to include an array circuit compiled to perform predetermined processing, such as an FPGA (Field Programmable Gate Array), etc. The control unit 301 stores information to be stored during the execution of various types of processing in the memory 309. In addition, the control unit 301 can use a timer 310 to measure a time period.

[0076] The battery 302 supplies power required for the control unit 301 to control each unit of the RX 102, as well as power reception and communication, to the entire RX 102. In addition, the battery 302 stores power received via the power reception coil 305.

[0077] In the power receiving coil 305, an induced electromotive force is generated by the electromagnetic wave emitted from the power transmitting coil 205 of the TX 101. The power receiving unit 303 obtains the power generated in the power receiving coil 305. The power receiving unit 303 obtains the AC power generated by electromagnetic induction in the power receiving coil 305, converts the AC power into DC power or AC power of a predetermined frequency, and outputs the power to the charging unit 313 that performs processing for charging the battery 302. That is, the power receiving unit 303 supplies power to the load in the RX 102, and the charging unit 313 and the battery 302 are examples of such loads. The above-mentioned GP is the power guaranteed to be output from the power receiving unit 303. In addition, the power receiving unit 303 notifies the control unit 301 of the current received power. In this way, at any timing, the control unit 301 can know the received power at that timing. Note that it is allowed to adopt a configuration in which an entity other than the power receiving unit 303 measures the received power and notifies the received power to the control unit 301.

[0078] The placement detection unit 304 detects that the RX 102 is placed on the charging stand 103 based on the WPC standard. The placement detection unit 204 detects, for example, at least one of a voltage value and a current value of the power receiving coil 305 when the power receiving unit 303 receives a digital Ping of the WPC standard via the power receiving coil 305. For example, when the voltage value drops below a predetermined voltage threshold or when the current value exceeds a predetermined current threshold, the placement detection unit 304 determines that the RX 102 is placed on the charging stand 103.

[0079] The communication unit 306 performs the control communication based on the WPC standard described above with the TX 101. The communication unit 306 communicates with the TX 101 by demodulating the electromagnetic wave input from the power receiving coil 305 to acquire the information transmitted from the TX 101, and by load modulating the input electromagnetic wave to superimpose the information to be transmitted to the TX 101 on the electromagnetic wave. That is, the communication unit 306 communicates by superimposing on the electromagnetic wave transmitted from the power transmitting coil of the TX 101.

[0080] The notification unit 307 notifies the user of information using, for example, any visual, auditory, or tactile method. The notification unit 307 notifies the user of, for example, the charging status of the RX 102 and the Figure 1The state related to the power transmission of the wireless power transmission system of the TX 101 and RX 102 shown. The notification unit 307 is configured to include, for example, a liquid crystal display, an LED, a speaker, a vibration generation circuit, and other notification devices. The operation unit 308 has an acceptance function for accepting an operation performed by a user on the RX 102. The operation unit 308 is configured to include, for example, a button, a keyboard, a sound input device such as a microphone, a motion detection device such as an acceleration sensor and a gyroscope, or other input devices. Note that a device such as a touch screen in which the notification unit 307 and the operation unit 308 are integrated can be used. As described above, the memory 309 stores various types of information such as identification information and device configuration information, as well as control programs, etc. Note that the memory 309 can store information acquired by a functional unit different from the control unit 301. The timer 310 measures time using, for example, an up-counting timer for measuring a time period elapsed from the start time and a down-counting timer for counting down from a set time.

[0081] The charging unit 313 charges the battery 302 using the power supplied from the power receiving unit 303. In addition, under the control of the control unit 301, the charging unit 313 starts or stops charging the battery 302, and further adjusts the power used when charging the battery 302 based on the charging state of the battery 302. When the power used by the charging unit 313 changes, the power supplied from the power receiving unit 303 (that is, the power received in the RX 102) also changes accordingly. As described above, the charging unit 313 is a load in the RX 102. Note that the charging unit 313 and the battery 302 may also exist as other devices outside the RX 102. These devices may be, for example, devices that operate with the aid of power supplied based on the USB PD standard. In this case, the control unit 301 may obtain information on the size of the power required by the charging unit 313 from the charging unit 313 via communication of the USB PD standard. Under the control of the control unit 301, the output power setting unit 311 sets the output voltage for supplying power from the power receiving unit 303 to the charging unit 313 (that is, the load). The output power setting unit 311 includes a variable voltage unit.

[0082] Using the communication unit 306, the reacquisition instruction unit 312 instructs the TX 101 to start reacquiring the parameters used for the foreign object detection process. The parameters used for the foreign object detection process represent the pair of the received power and the power loss mentioned in the previous description of the calibration phase. Note that the reacquisition instruction unit 312 may be configured to operate entirely or partially on a processor different from the processor of the control unit 301, and may be implemented by a program operating on the control unit 301. The function of the reacquisition instruction unit 312 may be implemented by executing a program stored in, for example, the memory 309.

[0083] (Processing flow)

[0084] Subsequently, a description is given of an exemplary flow of processing performed by the TX 101 and the RX 102 .

[0085] [Processing in power transmission equipment]

[0086] Figure 4A and Figure 4B is a flowchart showing an exemplary flow of processing performed by TX 101. In the following, Figure 4A and Figure 4B Collectively referred to as Figure 4A and 4B . This processing can be implemented by, for example, the control unit 201 of TX 101 executing a program read out from the memory 209. This processing also includes processing in the re-acquisition request unit 212. Note that at least a part of the following process can be implemented by hardware. In this case, the hardware can be implemented by, for example, automatically generating a dedicated circuit using a gate array circuit such as an FPGA from a program for implementing each processing step using a predetermined compiler. In addition, the present processing can be started in response to power-on of TX 101, in response to an indication input by a user of TX 101 for starting a wireless charging application, or in response to TX 101 receiving power supply when connected to a commercial power supply. Note that the present processing can be started by another trigger.

[0087] In the process related to power transmission / reception, TX 101 first performs the process of the selection phase and the Ping phase defined as the WPC standard, and waits for the placement of RX 102 (S401). Specifically, TX 101 sends the analog Ping of the WPC standard in a repetitive and intermittent manner, and the placement detection unit 204 detects whether there is an object placed on the charging table 103 based on the change in current or voltage in the power transmission coil 205. In the case where it is detected that the object is placed on the charging table 103, TX 101 sends a digital Ping. In addition, in the case where there is a predetermined response (signal strength packet) to the digital Ping, TX 101 determines that the detected object is RX 102 and RX 102 is placed on the charging table 103. When the placement of RX 102 is detected, TX 101 performs the process of the I&C phase defined as the WPC standard, and uses the communication unit 206 to obtain identification information and device configuration information (capability information) from the RX 102 (S402).

[0088] Figure 7 The communication sequence 7a of FIG. 7A describes an exemplary flow of communication in the I&C phase. In the I&C phase, RX 102 sends an identification packet (ID packet) (F701) to TX 101. The ID packet stores a manufacturer code and a basic device ID as identification information of RX 102, and information elements that enable the corresponding version of the WPC standard to be specified as capability information of RX 102. RX 102 also sends a configuration packet (F702) to TX 101. The configuration packet includes the following as capability information of RX 102: a maximum power value that specifies the value of the maximum power that RX 102 can provide to a load, and information indicating whether a negotiation function of the WPC standard is provided.

[0089] Once TX 101 receives these packets, TX 101 sends ACK (F703), and the I&C phase ends. Note that TX 101 may acquire the identification information and device configuration information (capability information) of RX 102 from RX 102 using a method other than the communication in the I&C phase of the WPC standard. In addition, the identification information of RX 102 may be a wireless power ID of the WPC standard, or may be any other identification information that enables identification of the individual of RX 102. Information other than the above information may be included as capability information.

[0090] Back to Figure 4A and 4B , TX 101 negotiates with RX 102 through communication in the negotiation phase and determines GP (S403). Figure 7The communication sequence 7b of FIG. 7b describes an exemplary flow of communication in the negotiation phase. The GP is determined based on a specific request packet from the RX 102 and a response to the specific request packet from the TX 101. First, the RX 102 notifies the TX 101 of the value of the requested GP by sending a specific request packet (F711). The RX 102 determines the value of the requested GP based on the power required by itself. In the present embodiment, the value of the requested GP at this stage is, for example, 5 watts.

[0091] TX 101 determines whether to accept the request from RX 102 based on its own power transmission capability, and sends ACK (positive response) to RX 102 if the request is to be accepted, and sends NAK (negative response) to RX 102 if the request is not to be accepted. Note that Figure 7 7b describes an example in which TX 101 sends ACK (F712). In the case where TX 101 sends ACK, the value of GP is determined to be the same as the value requested by RX 102, and is stored in the memories of both TX 101 and RX 102. On the other hand, in the case where TX 101 sends NAK, the value of GP is a small default value (e.g., a value equal to or less than 5 watts). In one example, the default value is pre-stored in the memories of both TX 101 and RX 102. Note that the aforementioned method of determining GP is an example, and another method may be used to determine GP.

[0092] Return to Figure 4A and 4B , the input voltage setting unit 211 of the TX 101 determines the input voltage for supplying power from the power supply unit 202 to the power transmission unit 203 based on the GP determined in S403, and sets the input voltage on the power transmission unit 203 (S404). Note that this process also includes a process for waiting for the input voltage to be stably input to the power transmission unit 203 after the input voltage setting unit 211 sets the input voltage on the power transmission unit 203. Fig.10Table 1001 shows an example of an input voltage determined based on GP. By referring to table 1001, the input voltage setting unit 211 can, for example, set an input voltage of 5 volts for a case where the determined GP is 5 watts, set an input voltage of 9 volts for a case where the determined GP is 15 watts, and so on. Here, each value of table 1001 is a value of an input voltage predetermined based on the electrical characteristics of the power transmission unit 203 of TX 101 in order to efficiently transmit the determined power, and is maintained in, for example, the memory 209. Note that in the case where the power supply unit 202 and the input voltage setting unit 211 are external devices operating based on the USB PD standard, the input voltage setting unit 211 can acquire the values ​​in table 1001 from the control unit 201 via communication. Alternatively, table 1001 can be maintained in the memory 209 as a table specified by the USB PD standard.

[0093] Return to Figure 4A and 4B After setting the input voltage, the TX 101 acquires parameters used for foreign matter detection processing through processing in the calibration phase (S405). Figure 7 The communication sequence 7c of FIG. 7c describes an exemplary flow of communication in the calibration phase. RX102 transmits a received power packet (F721) via the communication unit 306. The received power packet includes a received power value indicating the current received power. TX101 stores the information of the received power included in the received power packet as a parameter for foreign object detection processing, and then returns ACK (F722). As will be described below, F721 and F722 are repeated at least twice.

[0094] For example, the RX 102 provides notifications related to the received power in two different states: a state where no load is connected, that is, a state close to 0 watts; and a state where a load is connected and power close to the value of GP is being received. In order to provide these notifications, communication of the received power packet and ACK occurs twice, and information of the two received powers is stored in the TX 101. Note that in addition to the aforementioned notifications, it is also allowed to provide notifications related to the intermediate received power between the state close to 0 watts and the state where power close to the value of GP is being received. In the present embodiment, it is assumed that in the case where the value of GP exceeds 5 watts, notifications related to the received power are provided at power value intervals of about 5 watts. For example, in the case where the value of GP is 15 watts, notifications related to the received power are provided in the state where four types of power (that is, about 0 watts, about 5 watts, about 10 watts, and about 15 watts) are received. Note that the power value interval may not be constant and may not be 5 watts. The TX 101 stores all the received power of which it is notified in the memory 209 as parameters used for foreign matter detection processing.

[0095] In addition, the RX 102 adds information expressing this meaning to the first receiving power packet after the calibration phase starts. Specifically, the value of the mode (Mode) included in the receiving power packet is set to 1. In addition, with respect to the second and subsequent receiving power packets in the calibration phase, the value of the mode is set to a value other than 1 (for example, 2). In this way, the TX 101 can recognize the start of the calibration phase based on the value of the mode. Note that the above method of recognizing the start of the calibration phase is an example; the mode may take other values, and recognition may be performed based on values ​​other than the mode. In addition, the start may be recognized based on another packet.

[0096] Once the TX 101 recognizes the start of the calibration phase by receiving the receiving power packet with the mode value of 1, the TX 101 discards the parameters for the foreign object detection process that have been stored in the memory 209. Then, the TX 101 stores the receiving power included in the receiving power packet received from the RX 102 and the power loss indicating the difference from the transmitted power in the power transmission unit 203 at this time in association with each other in the memory 209. Note that instead of the power loss, the transmitted power may be stored in association with the receiving power, or both the power loss and the transmitted power may be stored in association with the receiving power. Thereafter, when the TX 101 receives the receiving power packet with the mode value of 2, the TX 101 additionally stores the receiving power included in the packet and the power loss at this time in association with each other in the memory 209.

[0097] Figure 8 Table 800 shows an example of the contents of the parameters used for the foreign object detection process stored in the memory 209. For example, the information in row 801 indicates that the power loss is 0.6 watts when the received power in the RX 102 is 0.1 watts, and is stored when a received power packet (mode = 1) is received from the RX 102. Thereafter, each time a received power packet (mode = 2) is received from the RX 102, the TX 101 adds a row (for example, row 802) to the table 800. Note that, as described above, in the case of receiving a received power packet with mode = 1, the TX 101 clears the contents up to that point, and then stores rows again starting from row 801.

[0098] Back to Figure 4A and 4B, TX 101 starts foreign object detection processing and power transmission (S406, S407). Foreign object detection processing in TX 101 is performed as follows. First, TX 101 periodically obtains information on the current received power from RX 102. A notification related to the received power from RX 102 used in foreign object detection processing is provided via a received power packet with a mode value of 0, for example. In the case where TX 101 receives a received power packet (mode = 0), TX 101 does not update the parameters used in foreign object detection processing (table 800). Then, TX 101 uses Figure 8 The expected value of the power loss corresponding to the received power is derived by linear interpolation between the respective points using the parameters used in the foreign object detection process in the table 800. The above-mentioned Expression 1 can be used for the linear interpolation.

[0099] TX 101 calculates the power loss based on the difference between the transmitted power (current transmitted power) measured for the first time after the received power is acquired and the received power acquired. Then, TX 101 compares the difference between the calculated power loss and the expected value with the threshold. When the difference between the calculated power loss and the expected value exceeds the threshold, TX 101 determines that there is power loss caused by foreign matter such as a metal sheet, and determines that the foreign matter exists in the power transmission range. When it is determined that the foreign matter exists in the power transmission range, TX 101 uses the control unit 201 to limit the power transmission. Specifically, the control unit 201 controls the power transmission unit 203 to stop the power transmission or reduce the power transmission. In addition, the control unit 201 can notify the RX 102 of the presence of foreign matter via the communication unit 206. In addition, the control unit 201 can notify the RX 102 of the limitation on the power transmission.

[0100] The following parameters are used for foreign body detection processing: Figure 8 A specific description of the foreign matter detection process is provided based on the exemplary case of the contents shown in rows 801 and 802 of table 800. Fig. 9 The curve Fig. 9 Point A and point B in a are obtained by plotting row 801 and row 802, respectively, in a graph in which received power and power loss are represented by axes. TX 101 derives an expected value of power loss corresponding to the current received power by linear complementation represented by a straight line connecting point A and point B. For example, in the case where the value of the current received power (RP) is 2.5 watts, the values ​​of rows 801 (RP1 = 0.1 watt, PL1 = 0.6 watt) and 802 (RP1 = 4.9 watts, PL2 = 1.6 watts) are applied to the above-mentioned expression 1. In this case, the expected value PL of power loss is as follows.

[0101] PL=(1.6-0.6) / (4.9-0.1)*(2.5-0.1)+0.6=1.1

[0102] Then, using the transmitted power measured for the first time after the received power is acquired as the current transmitted power, TX101 calculates the power loss based on the difference between the current transmitted power and the current received power (RP = 2.5 watts). When the difference between the value of the power loss calculated in the above manner and the expected value (PL) of 1.1 watts exceeds the threshold, it is determined that there is power loss caused by foreign matter, and it is determined that there is a foreign matter in the transmission range. Here, the threshold value may be an absolute value such as 1 watt, or may be a relative value such as 50% of the expected value. Information related to the threshold value is stored in the memory 209. In addition, the threshold value may be changed in a step-by-step manner according to the received power and the expected value of the power loss.

[0103] exist Figure 4A and 4B In the example, TX 101 also accepts GP negotiation from RX 102 during power transmission (S408). If GP is changed as a result of the negotiation, TX 101 refers to Fig.10 The input voltage to the power transmission unit 203 is determined by using the table 1001 of FIG. 1001. In the case where the current input voltage is to be changed (in the case where the determined input voltage is different from the current input voltage) (“Yes” in S409), the input voltage setting unit 211 changes the input voltage (S410). The re-acquisition request unit 212 waits for the input voltage to be stabilized (S410), and then sends a request for re-acquiring the parameters used for the foreign object detection process to the RX 102 (S411). On the other hand, in the case where the current input voltage is not to be changed (in the case where the determined input voltage is the same as the current input voltage) (“No” in S409), the processing of S410 and S411 is skipped. Subsequently, the TX 101 waits for receiving an instruction for re-acquiring the parameters used for the foreign object detection process from the RX 102 in a predetermined time period (S412). Here, the purpose of waiting for the instruction for re-acquiring from the RX 102 in a predetermined time period is to provide the RX 102 that has received the re-acquisition request with a time period for executing the processing for sending an instruction for re-acquiring the parameters used for the foreign object detection process.

[0104] In the case where an instruction for reacquiring the parameters used for the foreign object detection process is received from the RX 102 ("Yes" in S413), the process returns to S405, and the TX 101 reacquires the parameters used for the foreign object detection process through the process in the calibration phase. Note that whether or not an instruction for reacquiring is received from the RX 102 is always monitored during the power transmission of the TX 101. Then, in the case where an instruction for reacquiring is received from the RX 102, the process proceeds from S413 to S405, and the TX 101 performs reacquiring the parameters used for the foreign object detection process. That is, regardless of whether the input voltage changes, in the case where an instruction for reacquiring the parameters used for the foreign object detection process is received from the RX 102, the TX 101 starts reacquiring the parameters used for the foreign object detection process ("Yes" in S413). In addition, in the case where the GP is not updated in S408 and it is determined in S409 that the input voltage is not changed, the process of S412 (the process for waiting for receiving the instruction for reacquiring) can be skipped. In addition, although the input voltage is changed based on the GP value determined by negotiation with the RX 102 in S409, this is not intended to be limiting. For example, the control unit 201 may acquire the power transmitted to the RX 102, and may set and change the input voltage to the power transmission unit 203 based on the power transmitted. In addition, this case may also adopt a configuration in which the input voltage is changed based on the USB PD standard.

[0105] In the case where no instruction for reacquiring the parameters used for the foreign object detection process is received from RX 102 ("No" in S413), power transmission is continued for a predetermined period of time (S414). Here, the predetermined period of time is, for example, 1 second. In the case where no request for stopping power transmission is received and no foreign object is detected during the power transmission ("No" in S415), the process returns to S408 and the above process is repeated. In the case where a request for stopping power transmission is received or a foreign object is detected ("Yes" in S415), TX 101 stops power transmission (S416). Thereafter, TX 101 determines whether to end the process (S417). In the case where it is determined that the process is not to be ended ("No" in S417), the process returns to S401 and the above process is repeated. In the case where it is determined that the process is to be ended ("Yes" in S417), the current process ends. For example, whether to end the process is determined based on the content of the operation performed by the user on the operation unit 208.

[0106] [Processing in Power Receiving Equipment]

[0107] Then, use Figure 5A and Figure 5B A description is given of an exemplary flow of processing performed by RX 102. In the following, Figure 5A and Figure 5B Collectively referred to as Figure 5A and 5B . The present processing can be implemented by, for example, the control unit 301 of RX 102 executing a program read out from the memory 309. The present processing also includes the processing in the re-acquisition indication unit 312. Note that at least a part of the process of the present processing to be described below can be implemented by hardware. In this case, the hardware can be implemented by, for example, automatically generating a dedicated circuit using a gate array circuit such as an FPGA from a program for implementing each processing step using a predetermined compiler. In addition, the present processing can be started in response to the power-on of RX 102, in response to the startup of RX 102 caused by the supply of power from the battery 302 or TX 101, or in response to an instruction for starting a wireless charging application input by a user of RX 102. Note that the present processing can be started by another trigger.

[0108] After starting the processing related to power transmission / reception, the RX 102 performs the processing of the selection phase and the Ping phase defined as the WPC standard, and waits for itself to be placed on the TX 101 (S501). Then, the RX 102 detects that it is placed on the charging stand 103 of the TX 101 by, for example, detecting a digital Ping from the TX 101. Then, when the digital Ping is detected, the RX 102 transmits an SS packet including a power reception voltage value to the TX 101.

[0109] When the RX 102 detects that it is placed on the charging pad 103 of the TX 101, it uses the communication unit 306 to perform the communication in the above-mentioned I&C phase and sends the identification information and the device configuration information (capability information) to the TX 101 (S502). Then, the RX 102 negotiates with the TX 101 through the communication in the negotiation phase and determines the GP (S503). Specifically, as described in conjunction with the processing in the power transmitting device, based on Figure 7 The communication in the negotiation phase is performed based on the specific request packet shown in the communication sequence 7b and the response to the specific request packet.

[0110] The output power setting unit 311 determines the output voltage for supplying power from the power receiving unit 303 to the charging unit 313 based on the GP determined in S503, and sets the output voltage on the charging unit 313 (S504). This process also includes a process for waiting for the output voltage to be stably output to the charging unit 313 after the output power setting unit 311 sets the output voltage.

[0111] Fig.10Table 1002 shows an example of an output voltage determined based on GP. By referring to table 1002, the output power setting unit 311 can determine an output voltage of 5 volts for a case where GP is 5 watts, an output voltage of 9 volts for a case where GP is 15 watts, and so on. Here, it is assumed that each value of table 1002 is a value predetermined based on the electrical characteristics of the charging unit 313 of RX 102 for efficient charging, and is retained in the memory 309. Note that in the case where the charging unit 313 is an external device operating based on the USB PD standard, the value of the output voltage can be acquired from the charging unit 313 via communication, or can be retained in the memory 309 as a table specified by the USB PD standard. Note that in the present embodiment, it is assumed that table 1002 retained in RX 102 and table 1001 retained in TX 101 have the same content. For example, in the case where both TX 101 and RX 102 comply with the USB PD standard, the table may have the same content. Note that the content may comply with other standards.

[0112] Subsequently, RX 102 provides a notification about the received power information for causing TX 101 to acquire the parameters used for the foreign object detection process via the communication in the above-mentioned calibration phase (S505). Subsequently, RX 102 connects the charging unit 313 as a load to the power receiving unit 303, and starts power reception in the power transmission phase (S506).

[0113] When receiving power wirelessly from TX 101, RX 102 acquires the power required by charging unit 313 (S507). This value may be stored in memory 309 in advance, or may be acquired from an external device via communication if charging unit 313 is an external device. If the power required by charging unit 313 falls within the range of the current GP ("No" in S508), power reception continues without changing the GP for a predetermined period of time (S515). The predetermined period of time is, for example, 1 second. Afterwards, if charging unit 313 completes charging of battery 302, power reception stops ("Yes" in S516, S517), and the current process ends. Otherwise ("No" in S516), the process returns to S507 to continue charging.

[0114] Here, while the power reception continues in S515, the RX 102 repeatedly and periodically notifies the TX 101 of the current received power. The TX 101 detects foreign matter based on this information of the received power. The notification related to the current received power is provided using the received power packet of the WPC standard. Here, the received power packet is also used in the communication in the calibration phase described above. For this reason, the RX 102 makes it possible to distinguish whether it is a notification for causing the TX 101 to store parameters used for foreign matter detection processing in the calibration phase or a notification related to the current received power for performing foreign matter detection processing in the TX 101. Specifically, this is done by setting the mode value of the received power packet to 0. Note that another value different from the mode value used in the calibration phase may be used, or the aforementioned identification may be made based on an entity other than the mode value. For example, it may be possible to make identification by using different types of packets in the calibration phase and the power transmission phase.

[0115] On the other hand, in the case where the acquisition of power necessary for the charging unit 313 causes the need to change the GP (Yes in S508), the RX 102 negotiates with the TX 101 and changes the GP (S509). Here, in the case where the GP is to be set to a predetermined size or higher, the RX 102 can perform device authentication for the TX 101 via communication. By performing device authentication, only a predetermined size or higher power guaranteed to satisfy the conditions of the WPC standard and other standards can be received from the TX 101. An example of device authentication is challenge-response communication using an electronic certificate.

[0116] Then, the RX 102 determines the output voltage to the charging unit 313 based on the updated GP. Fig.10 The output voltage is determined by table 1002 of FIG. 1001. If the current output voltage needs to be changed (“Yes” in S510), the output power setting unit 311 changes the output voltage to the charging unit 313 and waits for the voltage to stabilize (S511). If the current output voltage does not need to be changed (“No” in S510), the processing of S511 is skipped.

[0117] Subsequently, the RX 102 waits for a predetermined period of time to receive a request for reacquiring parameters used in the foreign matter detection process from the TX 101 (S512). Figure 7 The communication sequence 7b described for updating GP is completed after the communication Figure 4A and 4B When “Yes” is obtained in S409, the predetermined time period in S512 is, for example, a time period longer than the time period required for the TX 101 to complete the processing of S410 and S411. Note that it is assumed that the value of the predetermined time period is held in the memory 309 in advance.

[0118] In the case where a request for reacquiring the parameters used for the foreign object detection process is received from the TX 101, or in the case where the output voltage is changed in S511 ("Yes" in S513), the RX 102 sends an instruction for reacquiring the parameters used for the foreign object detection process to the TX 101 (S514). Then, the process proceeds to S505, and the process in the calibration phase is performed again using the TX 101. On the other hand, in the case where a request for reacquiring the parameters used for the foreign object detection process is not received from the TX 101 and the output voltage is not changed in S511 ("No" in S513), the process proceeds to S515. The processes in and after S515 are as described above.

[0119] Here, the instruction for reacquiring the parameters used for the foreign object detection process sent by RX 102 may be a packet of the WPC standard, or may be another packet that TX 101 can recognize. Alternatively, in the case where RX 102 receives a request for reacquiring the parameters used for the foreign object detection process from TX 101, an affirmative response (ACK) to the request may be used as an instruction for reacquiring. In addition, the instruction for reacquiring the parameters used for the foreign object detection process sent by RX 102 may be the same as the packet indicating the start of the calibration phase. That is, RX 102 may reacquire the parameters used for the foreign object detection process by sending a WPC standard packet. Figure 7 The TX 101 issues an instruction for reacquiring the parameters used in the foreign object detection process by using F721 in the communication sequence 7c. As a result, the TX 101 clears the stored parameters used in the foreign object detection process and starts the communication in the calibration phase. That is, the parameters used in the foreign object detection process are reacquired.

[0120] In addition, despite Figure 5A and 5BA process in which an instruction for reacquiring the parameters used for the foreign object detection process may be issued in the case where the GP has been changed is described, but this is not intended to be limiting. For example, in the case where it is determined in S508 that the GP will not be changed ("No" in S508), the process may proceed to S510 with S509 skipped. In this way, regardless of the change in GP, ​​the RX 102 issues an instruction for reacquiring in response to receiving a request for reacquiring from the TX 101 during power reception, and performs reacquisition of the parameters used for the foreign object detection process ("Yes" in S513). This enables the RX 102 to issue an instruction for reacquiring even in the case where the TX 101 changes the input voltage without updating the GP and issues a request for reacquiring the parameters used for the foreign object detection process. Note that in this case, since the RX 102 monitors the reception of the request for reacquiring during power reception, in the case where the determination in S510 results in "No", it is allowed to adopt a configuration in which S511 and S512 are skipped.

[0121] [System Operation]

[0122] use Figure 6 , the following provides Figure 4A and 4B as well as Figure 5A and 5B A more specific description of the operating sequence of TX 101 and RX 102 has been described. Figure 6 FIG. 1 is a diagram showing an exemplary flow of processing performed in the wireless charging system according to the first embodiment. Figure 6 , time passes in the direction from top to bottom. It is assumed that in the initial state, the RX 102 is not placed on the TX 101, and the load (charging unit 313) of the RX 102 is not connected to the power receiving unit 303. In addition, it is assumed that the power required by the charging unit 313 of the RX 102 is initially 5 watts, and then increases to 15 watts after the power transmission phase starts.

[0123] First, TX 101 sends an analog Ping and waits for an object to be placed on the charging table 103 (F601, S501). Once RX 102 is placed (F602), the voltage or current of the analog Ping changes (F603). Based on the change, the placement detection unit 204 of TX 101 detects that an object has been placed (F604). Upon detecting the placement of the object, TX 101 sends a digital Ping (F605). RX 102 detects that it is placed on TX 101 by receiving the digital Ping (F606). In addition, TX 101 detects that the object placed on the charging table 103 is RX 102 via a response to the digital Ping. Subsequently, RX 102 sends identification information and device configuration information (capability information) to TX 101 via communication in the I&C phase (F607, S402, S502).

[0124] Subsequently, GP is determined between TX 101 and RX 102 (F608, S403, S503). Here, since RX 102 requests 5 watts which are initially required, GP is 5 watts. Since GP is 5 watts, TX 101 sets the input voltage (the voltage input to the power transmission unit 203 by the input voltage setting unit 211) to 5 volts with reference to table 1001 (F609, S404). Similarly, RX 102 sets the output voltage (the voltage output to the charging unit 313 by the output power setting unit 311) to 5 volts with reference to table 1002 (F610, S504).

[0125] Subsequently, the TX 101 acquires parameters for foreign matter detection processing corresponding to 0 watts to 5 watts as GP through processing in the calibration phase, and holds these parameters in the memory 209 (F611, S405, S505). This processing in the calibration phase is performed in a state where the input voltage of the TX 101 is 5 volts and the output voltage of the RX 102 is 5 volts. As a result, the contents of the parameters for foreign matter detection processing acquired by the TX 101 and held in the TX 101 are equivalent to, for example, Fig. 9 The curve Fig. 9 a.

[0126] Subsequently, TX 101 starts foreign object detection processing and power transmission (F612, S406, S407), RX 102 starts power reception (F612, S506), and continues power transmission / reception and foreign object detection processing at GP = 5 watts. Figure 4A and 4B The cycle of S408 → "No" in S409 → "No" in S412 → "No" in S413 → S414 → "No" in S415 → 408 in FIG. Figure 5A and 5BThe cycle of S507 → "No" in S508 → "No" in S515 → S516 → S507 in FIG. 1 corresponds to the cycle of S507 → "No" in S508 → S515 → S516 → S507 in FIG. 1. When the charging unit 313 needs 15 watts during power transmission / reception (F613, S507, S508 are "Yes"), the GP is updated to 15 watts between the TX 101 and the RX 102 (F614, S408, S509). Once the GP has been updated to 15 watts, the TX 101 changes the input voltage to 9 volts with reference to the table 1001 (F615, "Yes" in S409, S410), and sends a request for re-acquiring the parameters used for the foreign object detection process (F617, S411). On the other hand, RX 102 also changes the output voltage to 9V with reference to table 1002 (F616, YES in S510, S511), and sends an instruction for reacquiring parameters used for foreign matter detection processing (F618, YES in S512, S513, S514).

[0127] Since the TX 101 receives the instruction for reacquiring the parameters used for the foreign matter detection process (F618, S412, S413 are "Yes"), the TX 101 starts the process in the calibration phase (S405). On the other hand, the RX 102 also starts the process in the calibration phase (S514, S505). Therefore, the process in the calibration phase is performed again between the TX 101 and the RX 102, and the parameters used for the foreign matter detection process corresponding to 0 watts to 15 watts (which is the GP at this time) are acquired and maintained in the TX 101 (F619, S405, S505). This process in the calibration phase is performed in a state where the input voltage set by the input voltage setting unit 211 of the TX 101 is 9 volts and the output voltage set by the output power setting unit 311 of the RX 102 is 9 volts.

[0128] As described above, at the start of the calibration phase, TX 101 clears the parameters used for foreign object detection processing that have been maintained until then. Furthermore, it is assumed in the present embodiment that the parameters used for foreign object detection processing are acquired at intervals of 5 watts. Therefore, information of respective points corresponding to 0 watts, 5 watts, 10 watts, and 15 watts is acquired as parameters used for foreign object detection processing. Furthermore, at this time, the input voltage setting unit 211 of TX 101 and the output power setting unit 311 of RX 102 are each in a state where 9 volts is set as a voltage based on GP. That is, the two are in a state electrically different from the state where 5 volts is set to each of the two in F611. Therefore, as a result of the calibration processing in F619, the information of respective points corresponding to 0 watts, 5 watts, 10 watts, and 15 watts is acquired as parameters used for foreign object detection processing. Fig. 9 The curve Fig. 9 a curve with different points A and B Fig. 9b and holds the points A', B', C' and D' in TX 101 as parameters for foreign body detection processing. Fig. 9 The curve Fig. 9 The parameters used in the foreign object detection process shown in b are that power transmission / reception and foreign object detection are performed between TX 101 and RX 102 at GP=15W (F620, S406, S407, S506).

[0129] In the above operation, when the GP is changed from 5 watts to 15 watts, the input voltage and the output voltage are changed to 9 volts in the TX 101 and the RX 102 (F614 to F616), and the parameters used for the foreign matter detection process are reacquired in this state (F619). That is, in the case where the electrical states of both the TX 101 and the RX 102 have changed, the parameters updated according to the state after the change are used in the foreign matter detection process. In this way, foreign matter can be detected more accurately.

[0130] Note that although the TX 101 according to the aforementioned embodiment sends a request for reacquiring the parameters used for the foreign object detection process after changing the input voltage (S410, S411), this is not intended to be limiting. The input voltage may be changed within a predetermined period of time after sending the request for reacquiring the parameters used for the foreign object detection process. At this time, after receiving the request for reacquiring the parameters used for the foreign object detection process ("Yes" in S513), the RX 102 waits for a predetermined period of time until the change of the input voltage is completed on the TX 101 side, and then sends an instruction for reacquiring the parameters used for the foreign object detection process (S514). The predetermined period of time includes a period of time from setting the new input voltage until the input voltage is stable. In the case of this implementation, it is also possible to reacquire the parameters used for the foreign object detection process in a state where the input voltage has been changed (that is, in a state where the electrical state of the TX 101 has been changed). Note that in the above, it is allowed to wait for the TX 101 to provide a notification related to the completion of the change of the input voltage instead of waiting for the predetermined period of time. Alternatively, the RX 102 may monitor the power receiving voltage from the TX 101, and determine that the change of the input voltage in the TX 101 has been completed when the power receiving voltage has changed significantly; in this case, there is no need for a notification regarding the completion of the change of the input voltage from the TX 101. In either case, the parameters used for the foreign object detection process can be reacquired in a state where the input voltage has changed (that is, in a state where the electrical state of the TX 101 has changed).

[0131] In addition, TX 101 can Figure 8The parameters used for the foreign object detection process in the table 800 are stored in the memory 209 in association with the information of the input voltage set when these parameters are acquired. At this time, in the case where the start of the calibration phase is recognized, the TX 101 maintains the parameters used for the foreign object detection process in the table 800 without clearing these parameters. After the input voltage has been changed (S410), in the case where the parameters used for the foreign object detection process associated with the input voltage have been maintained, the TX 101 replaces the parameters used for the foreign object detection process with the parameters used for the foreign object detection process maintained in association with the changed input voltage. This can suppress the re-acquisition of the parameters used for the foreign object detection process that are performed multiple times in the state where the input voltage is the same, and can accordingly shorten the time period until the charging is completed by continuing to send power.

[0132] In addition, the TX 101 may be configured to provide a notification to the user via the notification unit 207 when the parameters used for the foreign object detection process are to be reacquired. This notification enables the user to know that the power transmission for charging is temporarily stopped for the purpose of reacquiring the parameters used for the foreign object detection process. For example, in a power receiving device whose LED is lit during charging of the RX 102, there is a case where the LED turns off when the power transmission for charging is temporarily stopped. At this time, the user can know that the LED that turns off does not mean a malfunction.

[0133] <Second Embodiment>

[0134] The first embodiment has been described with respect to the case where the table 1002 held in the RX 102 and the table 1001 held in the TX 101 have the same contents. The second embodiment will be described with respect to the case where the relationship between the GP in the TX 101 and the input voltage to the power transmission unit 203 is different from the relationship between the GP in the RX 102 and the output voltage to the power transmission unit 303. For example, instead of Fig.10 Table 1002, RX 102 will Fig.11 The table 1102 is held in the memory 309. In addition, the following describes a case where the power required by the charging unit 313 of the RX 102 is initially 5 W, then increases to 10 W after the power transfer phase starts, and then further increases to 15 W. Note that the other structures are similar to those of the first embodiment.

[0135] Will use Fig.12 The operation sequence of the TX 101 and the RX 102 according to the second embodiment will be described. Fig.12 FIG. 1 is a diagram showing an exemplary flow of processing performed in the wireless charging system according to the second embodiment. Fig.12 The time elapses from the time of placement detection until the power transmission / reception and foreign object detection processing is performed with a 5-watt GP. Figure 6 (F601 to F612, S401 to S407, S501 to S506) are the same. In F612, the input voltage of TX 101 is 5 volts, and the output voltage of RX 102 is 5 volts.

[0136] When the charging unit 313 needs 10 watts (F1201, S507, S508 are "yes"), the GP is updated to 10 watts between the TX 101 and the RX 102 (F1202, S408, S509). Once the GP has been updated to 10 watts, the TX 101 maintains the input voltage at 5 volts with reference to the table 1001 (F1203, S409 are "no"), and waits for an instruction from the RX 102 for reacquiring the parameters used for the foreign object detection process (S412). On the other hand, the RX 102 changes the output voltage to 9 volts with reference to the table 1002 (F1204, S510 are "yes", S511), and sends an instruction for reacquiring the parameters used for the foreign object detection process (F1205, S512, S513 are "yes", S514).

[0137] Upon receiving the instruction for reacquiring the parameters used for the foreign object detection process, the TX 101 starts the process in the calibration phase (S412, Yes in S413, S405). On the other hand, the RX 102, which has sent the instruction for reacquiring the parameters used for the foreign object detection process, also starts the process in the calibration phase (S514, S505). Therefore, the process in the calibration phase is performed again between the TX 101 and the RX 102, and the parameters used for the foreign object detection process corresponding to 0 watts to 10 watts (which is the GP at this time) are acquired and maintained in the TX 101 (F1206, S405, S505). This process in the calibration phase is performed in a state where the input voltage set by the input voltage setting unit 211 of the TX 101 is 5 volts and the output voltage set by the output power setting unit 311 of the RX 102 is 9 volts. The foreign object detection process executed by the TX 101 during the power transmission / reception period of GP=10W uses the parameters for the foreign object detection process acquired in the process in the calibration phase (F1207, S406, S407, S506).

[0138] After that, when the charging unit 313 needs 15 watts (F1208, S507, S508 are "yes"), the GP is updated to 15 watts between the TX 101 and the RX 102 (F1209, S408, S509). Once the GP has been updated to 15 watts, the TX 101 refers to the table 1001 to change the input voltage to 9 volts (F1210, S409 are "yes", S410), and sends a request for reacquiring the parameters used for the foreign object detection process (F1212, S411). Another method, the RX 102 refers to the table 1102 to maintain the input voltage at 9 volts (F1211, S510 are "no"), and waits for a request from the TX 101 to reacquire the parameters used for the foreign object detection process (S512).

[0139] When RX 102 receives a request for reacquiring the parameters used for foreign object detection processing (F1212, S512, S513 are "Yes"), RX 102 sends an instruction for reacquiring the parameters used for foreign object detection processing (F1213, S514). Since TX 101 receives an instruction for reacquiring the parameters used for foreign object detection processing (F1213, S412, S413 are "Yes"), TX 101 starts the processing in the calibration phase (S405). On the other hand, RX 102, which has sent an instruction for reacquiring the parameters used for foreign object detection processing, also starts the processing in the calibration phase (S514, S505). Therefore, the processing in the calibration phase is performed again between TX 101 and RX 102, and the parameters used for foreign object detection processing corresponding to 0 watts to 15 watts (which is the GP at this time) are acquired and maintained in TX 101 (F1214, S405, S505). This process in the calibration phase is performed in a state where the input voltage of the TX 101 is 9 V and the output voltage of the RX 102 is 9 V. Using the parameters for the foreign object detection process obtained as a result of the foregoing, power transmission / reception and foreign object detection are performed between the TX 101 and the RX 102 at a GP of 15 W (F1215, S406, S407, S506).

[0140] As described above, according to the second embodiment, when the GP is changed from 5 watts to 10 watts (F1202), the input voltage of RX 102 is changed to 9 volts, while the input voltage of TX 101 is maintained at 5 volts (F1203, F1204). The parameters used for the foreign matter detection process are reacquired in the state where the input voltage of TX 101 is 5 volts and the input voltage of RX 102 is 9 volts (F1206). In addition, when the GP is changed from 10 watts to 15 watts (F1209), the input voltage of TX 101 is changed to 9 volts, while the input voltage of RX 102 is maintained at 9 volts (F1210, F1211). Then, the parameters used for the foreign matter detection process are reacquired in the state where the input voltage of TX 101 and the input voltage of RX 102 are 9 volts (F1214). That is, in the case where the electrical state of one of TX 101 and RX 102 has changed, the parameters updated according to the state are used to detect foreign matter. In this way, foreign matter can be detected more accurately.

[0141] <Third Embodiment>

[0142] In the third embodiment, when the GP is updated, even if the input voltage of the TX 101 and the output voltage of the RX 102 are not changed, the parameters used for the foreign matter detection process are added. Fig.13A , Fig. 13B and Fig.14A , Fig. 14B 1 and 102, respectively, show the processing of TX 101 and the processing of RX 102 according to the third embodiment. Fig.13A and Fig. 13B Collectively referred to as Fig.13A and 13B ,and Fig.14A and Fig. 14B Collectively referred to as Fig.14A and 14B The difference from the first embodiment is that S1301 is added to Figure 4A and 4B The TX 101 in the processing and S1401 is added to Figure 5A and 5B The other structures are similar to those of the first embodiment.

[0143] Now, a description is given of the processing used in the case where the GP is updated from 5 watts to 10 watts in the third embodiment. First, as a Figure 7 The communication sequence 7b is used to update the GP (S408, S508 is "yes", S509). Fig.10Table 1001 and Table 1002 are updated, and neither the input voltage of TX 101 nor the output voltage of RX 102 is changed (No in S409, No in S510). Therefore, TX 101 does not send a request for reacquiring the parameters used for foreign object detection processing, and RX 102 does not send an instruction for reacquiring the parameters used for foreign object detection processing. At this time, RX 102 sends a request for adding the parameters used for foreign object detection processing based on the updated GP (No in S513, S1401). In addition, TX 101 adds the parameters used for foreign object detection processing based on the addition request (No in S413, S1301).

[0144] Here, an explanation is given of the addition of parameters used for foreign object detection processing. RX 102 receives about 10 watts of power as the updated GP by temporarily increasing the received power in the power receiving unit 303, and notifies TX 101 of the received power at this time and a request to add parameters used for foreign object detection processing. Note that the notification related to the received power and the request to add parameters used for foreign object detection processing can be sent together via one packet, or can be sent separately via different packets. For example, the received power packet with the mode value of 2 already described in the first embodiment can be used. Upon receiving the received power packet with the mode value of 2, TX 101 adds a pair of received power and power loss to table 800 ( Figure 8 ).

[0145] The TX 101 calculates the power loss based on the received power value received along with the request to add the parameter used in the foreign object detection process and the value of its own transmitted power at that time, and adds the power loss as the parameter used in the foreign object detection process. For the purpose of describing a specific example, it is assumed that the TX 101 obtains the following in the first calibration phase of S405: Figure 8 801 and 802, and obtain Fig. 9 The curve Fig. 9 a. Then, assume that in S1301, 9.9 watts of received power is received together with a request for adding parameters for foreign object detection processing, and the transmitted power at this time is, for example, 13.4 watts. In this case, row 803 including a power loss of 3.5 watts (which is the difference between the received power and the transmitted power) is added as a parameter for foreign object detection processing. Row 803 is equivalent to Fig. 9 The curve Fig. 9 Point C in c. In this way, when the received power and power loss in the RX 102 change nonlinearly, the TX 101 can detect foreign matter more accurately.

[0146] Here, in the case where the GP is changed from 5 watts to 10 watts, neither the input voltage of TX 101 nor the output voltage of RX 102 is changed, so the electrical state is not changed. Fig. 9 The curve Fig. 9 b) from 0 watts, and the already acquired parameters can be used. In this case, as has been described in the third embodiment, completing the addition process without reacquiring the parameters can shorten the time period during which the power transmission for charging is stopped, and end the charging in a shorter time period.

[0147] Note that in the case where the updated GP is extremely high, the RX 102 may provide notifications about the values ​​of multiple received power, for example, at intervals of about 5 watts. The TX 101 may derive power losses corresponding to the multiple received power values, respectively, and add multiple parameters used in the foreign object detection process. In this way, the accuracy of linear complementarity increases, thereby enabling more accurate detection of foreign objects.

[0148] <Other embodiments>

[0149] 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 are caused to read out and execute the program. The present invention can also be implemented by a circuit (e.g., ASIC) for implementing one or more functions.

[0150] 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 powered device, comprising: a power receiving unit for wirelessly receiving power from the power transmitting device; A communication unit, configured to communicate with the power transmission device; as well as Changing unit, used to change the voltage, wherein the communication unit transmits a first received power packet including information indicating a first received power value to the power transmitting device, After transmitting the first power receiving power packet, the changing unit changes the voltage of the power receiving device based on the authentication of the power transmitting device, the communication unit transmits a second power receiving power packet including information indicating a second power receiving power value to the power transmitting device after transmitting the first power receiving power packet and after changing the voltage of the power receiving device, and After transmitting the second power reception power packet, the communication unit transmits a third power reception power packet including information indicating a third power reception power value to the power transmitting apparatus.

2. The powered device according to claim 1, further comprising: A changing unit is configured to change a voltage to be supplied to a load based on power required by the load, the load consuming the power that the power receiving unit has received.

3. The powered device according to claim 2, further comprising: A negotiation unit is configured to negotiate with the power transmission device to change the power to be transmitted based on the power required by the load.

4. The power receiving device according to claim 1, wherein: When the first received power packet is transmitted, a calibration process is initiated.

5. The power receiving device according to claim 4, wherein: When the second received power packet is transmitted, the calibration process is initiated again.

6. The power receiving device according to claim 4, wherein: Through the calibration process, parameters to be used in the foreign object detection process performed by the power transmitting device are obtained.

7. The power receiving device according to claim 1, wherein: The authentication is based on an electronic certificate.

8. A method performed by a powered device, comprising: transmitting a first received power packet including information indicating a first received power value to the power transmitting device; After transmitting the first power receiving power packet, changing the voltage of the power receiving device based on authentication of the power transmitting device; after changing the voltage of the power receiving device, transmitting a second power receiving power packet including information indicating a second power receiving power value to the power transmitting device; as well as After the second received power packet is transmitted, a third received power packet including information indicating a third received power value is transmitted to the power transmitting device.

9. The method according to claim 8, wherein: When the first received power packet is transmitted, a calibration process is initiated.

10. The method according to claim 9, wherein: When the second received power packet is transmitted, the calibration process is initiated again.

11. The method according to claim 9, wherein: Through the calibration process, parameters to be used in the foreign object detection process performed by the power transmitting device are obtained.

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