Power transmission equipment and methods used by power transmission equipment

Abstract

To suppress lowering of the detection accuracy of foreign substance detection.SOLUTION: A power reception device can receive power transmitted from a power transmission device that can execute first foreign substance detection and second foreign substance detection. The power reception device transmits, to the power transmission device, data used for the power transmission device to execute the first foreign substance detection, determines, before transmitting the data, whether a predetermined condition for the power transmission device to execute the second foreign substance detection different from the first foreign substance detection is satisfied, and transmits, to the power transmission device, a signal for executing the second foreign substance detection according to the determination.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to Power transmission equipment and methods used by power transmission equipment .

Background Art

[0002] In recent years, the technological development of wireless power transmission systems has been widely carried out. In Patent Document 1, a power transmission device and a power reception device compliant with the standard (hereinafter referred to as the Wireless Power Consortium standard (WPC standard)) formulated by the Wireless Power Consortium, a wireless charging standardization organization, are disclosed. Further, Patent Document 2 discloses foreign object detection in the WPC standard.

[0003] The WPC standard adopts a foreign object detection method called the Power Loss method. In the Power Loss method, first, the power loss in a state where there is no foreign object between the power transmission device and the power reception device is calculated in advance from the difference between the power transmitted from the power transmission device and the power received by the power reception device. Then, the power transmission device executes calibration processing assuming that the calculated value is the power loss in the normal state (state without foreign object) during power transmission. Moreover, when the power loss between the power transmission device and the power reception device calculated during subsequent power transmission exceeds a threshold value from the power loss in the reference normal state, it is determined that "there is a foreign object".

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In this case, even though foreign objects are actually present between the power transmission and receiving equipment, the calibration process described above may be performed as if no foreign objects were present. In this case, the presence or absence of foreign objects is determined based on the power loss in the state where foreign objects are present, which leads to a problem where the detection accuracy of foreign objects by the power transmission equipment decreases.

[0006] This invention has been made in view of the above problems, and aims to suppress the decrease in detection accuracy of foreign matter detection. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the present invention Power transmission equipment One aspect of this is, The system includes a power transmission means for wirelessly transmitting power to a power receiving device, and a detection means for performing a first foreign object detection process related to power loss and a second foreign object detection process related to the Quality Factor. The detection means performs the second foreign object detection process again if a predetermined time has elapsed since the previous second foreign object detection process, and if no foreign object is detected by the second foreign object detection process performed again, the detection means performs calibration related to the first foreign object detection process. [Effects of the Invention]

[0008] The present invention makes it possible to suppress the decrease in detection accuracy of foreign matter detection. [Brief explanation of the drawing]

[0009] [Figure 1] A diagram illustrating the configuration of a power transmission device according to the first embodiment. [Figure 2] A diagram illustrating the configuration of a power receiving device according to the first embodiment. [Figure 3] Functional block diagram of the control units for the power transmission and power receiving devices according to the first embodiment. [Figure 4] A sequence diagram showing the processing of a power transmission system according to the first embodiment. [Figure 5] A sequence diagram showing the processing in the Power Transfer phase of a power transmission system according to the first embodiment. [Figure 6] A flowchart illustrating the processing in the Power Transfer phase of the power receiving device according to the first embodiment. [Figure 7] A flowchart illustrating the processing in the Power Transfer phase of a power transmission device according to the first embodiment. [Figure 8]Sequence diagram showing the processing in the Power Transfer phase of the power transmission system according to the second embodiment. [Figure 9] Flowchart showing the processing in the Power Transfer phase of the power receiving device according to the second embodiment. [Figure 10] Flowchart showing the processing in the Power Transfer phase of the power transmitting device according to the second embodiment. [Figure 11] Diagram showing foreign object detection based on the Power Loss method. [Figure 12] Configuration diagram of the wireless power transmission system according to the first embodiment. [Figure 13] Flowchart showing the processing of the power transmission system according to the first embodiment. [Figure 14] Sequence diagram showing the processing in the Power Transfer phase of the power transmission system according to the third embodiment. [Figure 15] Flowchart showing the processing in the Power Transfer phase of the power receiving device according to the third embodiment. [Figure 16] Flowchart showing the processing in the Power Transfer phase of the power transmitting device according to the third embodiment. [Figure 17] Sequence diagram showing the processing in the Power Transfer phase of the power transmission system according to the fourth embodiment. [Figure 18] Flowchart showing the processing in the Power Transfer phase of the power receiving device according to the fourth embodiment. [Figure 19] Sequence diagram showing the processing in the Power Transfer phase of the power transmission system according to the fifth embodiment. [Figure 20] Flowchart showing the processing in the Power Transfer phase of the power receiving device according to the fifth embodiment. [Figure 21] Sequence diagram showing the processing in the Power Transfer phase of the power transmission system according to the sixth embodiment. [Figure 22]Flowchart showing the processing in the Power Transfer phase of the power receiving device according to the sixth embodiment. [Figure 23] Sequence diagram showing the processing in the Power Transfer phase of the power transmission system according to the seventh embodiment. [Figure 24] Flowchart showing the processing in the Power Transfer phase of the power receiving device according to the seventh embodiment.

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential for the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant descriptions are omitted.

[0011] <First Embodiment> <1. Foreign Object Detection Based on the Power Loss Method> Foreign object detection based on the Power Loss method defined in the Wireless Power Consortium standard (WPC standard) (hereinafter referred to as the first foreign object detection) will be described with reference to FIG. 11. The horizontal axis in FIG. 11 is the power transmitted by the power transmission device, and the vertical axis is the power received by the power receiving device. Note that a foreign object is an object that is not a power receiving device, and is, for example, an object such as a metal piece having conductivity.

[0012] First, the power transmission device transmits power to the power receiving device at a first transmission power value Pt1. Here, the power receiving device receives power at a first reception power value Pr1 (referred to as the Light Load state). The power transmission device then stores the first transmission power value Pt1. Here, the first transmission power value Pt1, or the first reception power value Pr1, is the minimum power. Also, the power receiving device controls the load so that the power it receives is the minimum power. For example, the power receiving device may disconnect the load so that the received power is not supplied to the load (charging circuit and battery, etc.).

[0013] Next, the receiving device reports the power value Pr1 of the first received power to the transmitting device. Upon receiving Pr1 from the receiving device, the transmitting device calculates that the power loss between the transmitting device and the receiving device is Pt1-Pr1(Ploss1), and can create a calibration point 1100 (point 1100) that shows the correspondence between Pt1 and Pr1.

[0014] Next, the power transmission device changes the transmission power value to the second transmission power value Pt2 and transmits power to the power receiving device. Here, the power receiving device receives power at the second received power value Pr2 (this is called the Connected Load state). The power transmission device then stores the first transmission power value Pt2. Here, the first transmission power value Pt2, or the first received power value Pr2, is the maximum power. Also, the power receiving device controls the load so that the power it receives is the maximum power. For example, the power receiving device connects so that the received power is supplied to the load.

[0015] Next, the receiving device reports Pr2 to the transmitting device. Upon receiving Pr2 from the receiving device, the transmitting device calculates that the power loss between the transmitting and receiving devices is Pt2-Pr2(Ploss2), and can create a calibration point 1101 (point 1101) that shows the correspondence between Pt2 and Pr2.

[0016] The power transmission device then performs linear interpolation between points 1100 and 1101 to create line 1102. Line 1102 shows the relationship between transmitted power and received power when there are no foreign objects around the power transmission device and power receiving device. Based on line 1102, the power transmission device can predict the power value that the power receiving device will receive when transmitting power at a predetermined transmission power in the absence of foreign objects. For example, if the power transmission device transmits power at a third transmission power value Pt3, it can be inferred from point 1103 on line 1102, where the transmission power value is Pt3, that the third received power value that the power receiving device will receive when transmitting at Pt3 will be Pr3.

[0017] As described above, power loss between the power transmission device and the power reception device under different load conditions can be determined based on multiple combinations of the power transmission power value of the power transmission device and the power reception power value of the power reception device under different load conditions. Furthermore, power loss between the power transmission device and the power reception device under all load conditions can be estimated by interpolating multiple combinations. In this way, the calibration process performed by the power transmission device and the power reception device to obtain the combination of power transmission power value and power reception power value will be referred to as the Calibration process (CAL process) below.

[0018] Here, let's assume that when the power transmission device actually transmits power to the power receiving device using Pt3, the power transmission device receives a value called the received power value Pr3' from the power receiving device. The power transmission device calculates Pr3-Pr3' (=Ploss_FO) by subtracting the received power value Pr3' actually received from the power receiving device from the received power value Pr3 in the state where no foreign object is present. This Ploss_FO can be considered as the power loss consumed by the foreign object when it is present between the power transmission device and the power receiving device. Therefore, if the power Ploss_FO that would have been consumed by the foreign object exceeds a predetermined threshold, it can be determined that a foreign object is present. Alternatively, the power transmission device may pre-calculate the power loss Pt3-Pr3 (Ploss3) between the power transmission device and the power receiving device from the received power value Pr3 in the state where no foreign object is present. Next, the power loss Pt3-Pr3'(Ploss3') between the power transmission and receiving devices in the presence of foreign matter is calculated from the received power value Pr3' received from the power receiving device in the presence of foreign matter. Then, the power Ploss_FO that would have been consumed by the foreign matter can be estimated by Ploss3'-Ploss3 (=Ploss_FO).

[0019] As described above, the power Ploss_FO, which is likely consumed by foreign matter, can be calculated as either Pr3-Pr3'(=Ploss_FO) or Ploss3'-Ploss3 (=Ploss_FO). In this specification, we will primarily describe the method of calculating Ploss3'-Ploss3 (=Ploss_FO), but the method of calculating Pr3-Pr3'(=Ploss_FO) is also applicable. This concludes the explanation of foreign matter detection based on the power loss method.

[0020] In the CAL process described above, the power receiving device transmits the received power value to the power transmitting device. This received power value must be the value obtained when there are no foreign objects between the power transmitting device and the power receiving device, and accurate foreign object detection using the Power Loss method is only possible when there are no foreign objects. However, in reality, when the power receiving device measures the received power value, there is a possibility that foreign objects may be present between the power transmitting device and the power receiving device, in which case the accuracy of foreign object detection deteriorates. Therefore, in this embodiment, we describe a method to prevent a decrease in the accuracy of foreign object detection using the Power Loss method when CAL processing is performed when foreign objects are present between the power transmitting device and the power receiving device.

[0021] <2. System Configuration> Figure 12 shows an example configuration of a wireless power transmission system (wireless charging system) according to this embodiment. In one example, this system is composed of a power receiving device 1 and a power transmitting device 2. Hereinafter, the power receiving device 1 will be referred to as RX1 and the power transmitting device 2 as TX2. RX1 is a device capable of receiving power transmitted from TX2, and in one example, it is an electronic device that charges its built-in battery with the received power. TX2 is an electronic device that wirelessly transmits power to RX1, which is placed on a charging base 3, which is part of TX2. Hereinafter, since the charging base 3 is part of TX2, "placed on the charging base 3" may be referred to as "placed on TX2". 4 is the range within which RX1 can receive power from TX2. Note that RX1 and TX2 may have functions to execute applications other than wireless charging. An example of RX1 is a smartphone, and an example of TX2 is an accessory device for charging that smartphone. RX1 and TX2 may be tablets, storage devices such as hard disk drives and memory devices, or information processing devices such as personal computers (PCs). Furthermore, RX1 and TX2 may be, for example, image input devices such as imaging devices (cameras, video cameras, etc.) or scanners, or image output devices such as printers, copiers, or projectors. Also, TX2 may be a smartphone. In this case, RX1 may be another smartphone or wireless earphones. Also, RX1 may be a vehicle such as an automobile, and TX2 may be a charger installed in the console of an automobile, etc.

[0022] This system performs wireless power transmission using an electromagnetic induction method for wireless charging, based on the WPC standard. Specifically, RX1 and TX2 perform wireless power transmission for wireless charging based on the WPC standard between the receiving antenna of RX1 and the transmitting antenna of TX2. The wireless power transmission method applied to this system is not limited to the method specified in the WPC standard, but may also be other methods such as electromagnetic induction, magnetic field resonance, field resonance, microwave, or laser. Furthermore, in this embodiment, wireless power transmission is used for wireless charging, but wireless power transmission may also be used for purposes other than wireless charging.

[0023] <3. Control flow for power transmission> In this embodiment, RX1 and TX2 communicate for power transmission and reception control based on the WPC standard. The WPC standard defines multiple phases, including a Power Transfer phase in which power transmission is performed and one or more phases before actual power transmission takes place, and necessary power transmission and reception control communication is performed in each phase.

[0024] Figure 13 shows the sequence for power transmission. The phases before power transmission may include the Selection phase (S1301), Ping phase (S1302), Identification and Configuration phase (S1303), Negotiation phase (S1304), and Calibration phase (S1305), starting from when RX1 is mounted on TX2. In the following, the Identification and Configuration phase will be referred to as the I&C phase.

[0025] In the Selection phase (S1301), TX2 intermittently transmits Analog Pings to detect that an object has been placed on the charging base 3 of TX2 (for example, that RX1 or a conductive piece has been placed on the charging base 3). TX2 detects at least one of the voltage and current values ​​of the transmitting antenna when the Analog Ping is transmitted. If the voltage value falls below a certain threshold or the current value exceeds a certain threshold, TX2 determines that an object is present and transitions to the Ping phase.

[0026] In the Ping phase, TX2 transmits a Digital Ping with a higher power than the Analog Ping. The magnitude of the Digital Ping is sufficient power to activate the control unit of RX1 mounted on TX2. RX1 notifies TX2 of the magnitude of the received voltage. In this way, TX2 recognizes that the object detected in the Selection phase is RX1 by receiving the response from RX1 that received the Digital Ping. Upon receiving notification of the received voltage value, TX2 transitions to the I&C phase. Alternatively, TX2 may measure the Q-Factor of the transmitting antenna (transmitting coil) before transmitting the Digital Ping. This measurement result is used when performing foreign object detection processing (second foreign object detection) using the Q-value measurement method (Quality Factor method).

[0027] In the I&C phase, TX2 identifies RX1 and obtains equipment configuration information (capability information) from RX1. Therefore, RX1 sends an ID Packet and a Configuration Packet to TX2. The ID Packet contains RX1's identifier information, and the Configuration Packet contains RX1's equipment configuration information (capability information). Upon receiving the ID Packet and Configuration Packet, TX2 responds with an acknowledgment (ACK). The I&C phase then ends.

[0028] In the Negotiation phase, the value of Guaranteed Power (hereinafter referred to as "GP") is determined based on the value of GP requested by RX1 and the transmission capacity of TX2. TX2 also performs foreign object detection (second foreign object detection) using the Q-value measurement method (Quality Factor method) in accordance with the request from RX1. Furthermore, the WPC standard specifies a method in which, after transitioning to the Power Transfer phase, the same processing as the Negotiation phase is performed again at the request of RX1. The phase in which these processes are performed after transitioning from the Power Transfer phase is called the Renegotiation phase.

[0029] In the Calibration phase, the CAL process described above is performed based on the WPC standard. RX1 also notifies TX2 of a predetermined received power value (received power value under light load conditions / received power value under maximum load conditions), and TX2 performs adjustments to ensure efficient power transmission. The received power value notified to TX2 may be used for foreign object detection processing (first foreign object detection) using the Power Loss method.

[0030] In the Power Transfer phase, control is performed for starting and continuing power transmission, as well as stopping power transmission due to errors or full charge. In this embodiment, CAL processing is also performed in the Power Transfer phase as needed, as described later. TX2 and RX1 communicate by superimposing signals onto electromagnetic waves transmitted from the transmitting or receiving antennas, using the same transmitting antenna (transmitting coil) and receiving antenna (receiving coil) used for wireless power transmission, for the purpose of controlling power transmission and reception. The range in which communication is possible between TX2 and RX1 is approximately the same as the power transmission range of TX2. In one example, communication between TX2 and RX1 is based on the WPC standard.

[0031] The WPC standard specifies the amount of power guaranteed when RX1 receives power from TX2, defined by a value called GP. GP indicates the power value that guarantees output to the load of RX1 (e.g., charging circuit, battery, etc.) even if the relative positions of RX1 and TX2 change, reducing the power transmission efficiency between the receiving and transmitting antennas. For example, if GP is 5 watts, even if the relative positions of the receiving and transmitting antennas change and the power transmission efficiency decreases, TX2 will control and transmit power in such a way that it can output 5 watts to the load within RX1.

[0032] The WPC standard also specifies a method for TX2 to detect the presence of objects other than power receiving devices (foreign objects) around TX2 (near the receiving antenna). Specifically, it specifies the Power Loss method (first foreign object detection), which detects foreign objects based on the difference between the power transmitted by TX2 and the power received by RX1, and the Q-value measurement method (second foreign object detection), which detects foreign objects based on changes in the quality coefficient (Q-value) of the TX2's transmitting antenna. Foreign object detection using the Power Loss method is performed after the CAL processing described above, and is executed during power transmission (the Power Transfer phase described later) based on that data. Foreign object detection using the Q-value measurement method is performed before power transmission (before Digital Ping transmission described later, during the Negotiation phase or Renegotiation phase).

[0033] <4. Processing sequence for power transmission> Next, the operation of TX2 and RX1 in steps S1301 to S1306 in Figure 3 will be explained using the sequence diagram in Figure 4.

[0034] TX2 repeatedly and intermittently transmits Analog Ping according to the WPC standard to detect objects within its power transmission range (S401). TX2 then performs the processes defined as the Selection phase and Ping phase of the WPC standard and waits for RX1 to be installed.

[0035] The user of RX1 brings RX1 (e.g., a smartphone) close to TX2 to charge it (S402). Specifically, this could involve placing RX1 on TX2. When TX2 detects the presence of an object within its power transmission range (S403, S404), it sends a WPC standard Digital Ping (S405). When RX1 receives the Digital Ping, it can understand that TX2 has detected RX1 (S406). Furthermore, when TX2 receives a predetermined response to the Digital Ping, it determines that the detected object is RX1 and that RX1 has been placed on the charging base 3.

[0036] When TX2 detects the placement of RX1, it obtains identification information and capability information from RX1 via I&C phase communication as defined by the WPC standard (S407). Here, the identification information of RX1 includes the Manufacturer Code and Basic Device ID. The capability information of RX1 includes information that can identify the version of the WPC standard it supports, a value indicating the maximum power that RX1 can receive (Maximum Power Value), and information indicating whether or not it has the WPC standard negotiation function. Note that TX2 may obtain the identification information and capability information of RX1 by means other than the I&C phase communication of the WPC standard. The identification information may also be any other identification information that can identify an individual RX1, such as a Wireless Power ID. The capability information may also include information other than those mentioned above.

[0037] Next, TX2 determines the values ​​of RX1 and GP through communication in the Negotiation phase as defined in the WPC standard (S408). Note that in S408, other procedures for determining GP may be performed in addition to the communication in the Negotiation phase as defined in the WPC standard. Also, if TX2 obtains information (for example in S407) indicating that RX1 does not support the Negotiation phase, it may not perform the Negotiation phase communication and may set the value of GP to a small value (for example, one predetermined in the WPC standard). In this embodiment, GP = 5 watts (5W).

[0038] After determining the GP, TX2 performs the CAL processing described above based on the GP. In the CAL processing, RX1 transmits information to TX2 that includes the received power under light load conditions (hereinafter referred to as the first received power information) (S409). In this embodiment, the first received power information is data corresponding to the received power of RX1 when the transmission power of TX2 is 250mW. The first received power information will be described as a received power packet (RP packet) that includes Received Power (mode1) as defined in the WPC standard, but other messages may be used. TX2 determines whether or not to accept the first received power information based on the transmission status of TX2. Here, if TX2 receives first received power information that includes data corresponding to received power exceeding the transmission power, it may decide not to accept the first received power information. Alternatively, if the ratio of received power to transmission power is below a threshold, TX2 may decide not to accept the first received power information. TX2 sends an acknowledgment (ACK) to RX1 if it accepts the first power reception information, or a negative acknowledgment (NAK) if it does not accept it (S410).

[0039] Next, when RX1 receives an ACK from TX2 (S410), RX1 determines whether it is possible to receive a larger power, and if so, sends a power output change instruction containing a positive value to increase the power transmitted from TX2 (S411). TX2 receives the power output change instruction and, if it is able to increase the transmission power, responds with an ACK and increases the transmission power (S412, S413). Since GP is set to 5W in S408, the transmission of power output change requests (+) like S411 and S414 is repeated until the transmission power reaches 5W.

[0040] If TX2 receives a power increase request from RX1 that exceeds GP (S414), it will respond with NAK to the power output change instruction, thereby suppressing power transmission beyond the specified limit (S415). Upon receiving NAK from TX2, RX1 determines that it has reached the predetermined received power and transmits data including the received power in the load-connected state to TX2 as second received power information (S417). In this embodiment, since GP is 5W, the second received power information is the received power information of RX1 when the power transmitted by TX2 is 5 watts. Here, the second received power information is a received power packet including Received Power (mode2) as defined in the WPC standard, but other messages may be used.

[0041] TX2 calculates the power loss between TX2 and RX1 based on the received power values ​​included in the first and second received power information and the transmitted power values ​​corresponding to each of the first and second received power information (S416). By interpolating these power losses, it is possible to calculate the power loss value between TX2 and RX1 at all times when TX2 is transmitting power (in this case, when TX2's transmitted power is from 250mW to 5W). TX2 sends an ACK to the second received power information from RX1 (S418), completing the Calibration phase and moving to the Power Transfer phase. Having determined that charging can be started, TX2 begins transmitting power to RX1, and charging of RX1 begins.

[0042] Next, TX2 and RX1 perform device authentication processing (S419), and if it is determined that the devices can handle a larger GP, they may reset the GP to a larger value, in this case 15W (S420). As described above in S411-S413, RX1 and TX2 change the transmission output using transmission output change instructions, ACK, and NAK to increase TX2's transmission power to 15W (S421-S424, S508). TX2 and RX1 then perform CAL processing again for GP=15W. Specifically, RX1 transmits a received power packet (hereinafter referred to as third received power information) containing data corresponding to the received power in RX1's load-connected state when TX2's transmission power is 15W (S425).

[0043] TX2 calculates the power loss between TX2 and RX1 based on the received power values ​​included in the first, second, and third received power information and the corresponding transmitted power values ​​(S426). This allows TX2 to estimate the power loss at all times when it transmits power (in this case, when TX2 transmits power from 250mW to 15W). After TX2 creates a calibration point using the third received power from RX1, it sends an ACK to RX1 (S427) and completes the CAL process. Having determined that it is ready to start the charging process, TX2 starts the power transmission process to RX1 (S428).

[0044] <5. Configuration of power transmission and power receiving equipment> Next, the configuration of the power transmission and power receiving devices according to this embodiment will be described. Note that the configuration described below is merely an example, and some (or all) of the described configurations may be replaced or omitted by other configurations that perform similar functions, and further configurations may be added to the described configurations. Furthermore, one block shown in the following description may be divided into multiple blocks, or multiple blocks may be integrated into one block. Also, each of the functional blocks shown below is assumed to be implemented as a software program, but some or all of the components included in this functional block may be implemented in hardware.

[0045] Figure 1 is a functional block diagram showing an example configuration of TX2 according to this embodiment. TX2 includes a control unit 101, a power supply unit 102, a power transmission unit 103, a communication unit 104, a power transmission antenna 105, a memory 106, and an antenna switching unit 107. In Figure 1, the control unit 101, power supply unit 102, power transmission unit 103, communication unit 104, memory 106, and antenna switching unit 107 are shown as separate components, but any multiple functional blocks among these may be implemented on the same chip.

[0046] The control unit 101 controls the entire TX2 by executing a control program stored, for example, in memory 106. The control unit 101 also performs control related to power transmission control, including communication for device authentication in TX2. Furthermore, the control unit 101 may perform control for executing applications other than wireless power transmission. The control unit 101 is configured to include one or more processors, such as a CPU (Central Processor Unit) or an MPU (Microprocessor Unit). The control unit 101 may also be configured with hardware dedicated to specific processing, such as an Application-Specific Integrated Circuit (ASIC). The control unit 101 may also be configured to include an array circuit, such as an FPGA (Field Programmable Gate Array), compiled to execute predetermined processing. The control unit 101 stores information that should be stored during the execution of various processes in memory 106. The control unit 101 can also measure time using a timer (not shown).

[0047] The power supply unit 102 supplies power to each functional block. The power supply unit 102 is, for example, a commercial power source or a battery. The battery stores power supplied from the commercial power source.

[0048] The power transmission unit 103 converts the DC or AC power input from the power supply unit 102 into AC frequency power in the frequency band used for wireless power transmission, and inputs this AC frequency power to the power transmission antenna 105 to generate electromagnetic waves for RX1 to receive power. For example, the power transmission unit 103 converts the DC voltage supplied by the power supply unit 102 into an AC voltage using a switching circuit with a half-bridge or full-bridge configuration using a FET (Field Effect Transistor). In this case, the power transmission unit 103 includes a gate driver that controls the ON / OFF state of the FET.

[0049] The power transmission unit 103 controls the power intensity of the electromagnetic waves to be output by adjusting the voltage (transmission voltage) or current (transmission current), or both, input to the power transmission antenna 105. Increasing the transmission voltage or transmission current increases the power intensity of the electromagnetic waves, while decreasing the transmission voltage or transmission current decreases the power intensity of the electromagnetic waves. Furthermore, the power transmission unit 103 controls the output of AC frequency power so that power transmission from the power transmission antenna 105 is started or stopped based on instructions from the control unit 101. The power transmission unit 103 is also assumed to have the capacity to supply enough power to output 15 watts (W) of power to the charging unit 206 (Figure 2) of the RX1, which complies with the WPC standard.

[0050] The communication unit 104 communicates with RX1 for power transmission control based on the WPC standard described above. The communication unit 104 modulates the electromagnetic waves transmitted from the power transmission antenna 105 and transmits information to RX1 to perform communication. The communication unit 104 also demodulates the electromagnetic waves transmitted from the power transmission antenna 105 that RX1 has modulated to obtain the information transmitted by RX1. In other words, the communication performed by the communication unit 104 is carried out by superimposing a signal on the electromagnetic waves transmitted from the power transmission antenna 105. The communication unit 104 may also communicate with RX1 using a different antenna than the power transmission antenna 105 and a different standard than the WPC standard, or it may selectively use multiple communication methods to communicate with RX1.

[0051] In addition to storing the control program, memory 106 can also store the states of TX2 and RX1 (transmitted power value, received power value, etc.). For example, the state of TX2 can be acquired by the control unit 101, and the state of RX1 can be acquired by the control unit 201 of RX1 (Figure 2) and received via the communication unit 104.

[0052] The transmitting antenna 105 has multiple antennas (coils). The antenna switching unit 107 selects and switches one of the multiple antennas (coils). Alternatively, the transmitting antenna 105 may consist of a single transmitting antenna 105 instead of multiple antennas. In that case, the antenna switching unit 107 is not necessary.

[0053] Figure 2 is a block diagram showing an example configuration of RX1 according to this embodiment. RX1 includes a control unit 201, a UI (user interface) unit 202, a power receiving unit 203, a communication unit 204, a power receiving antenna 205, a charging unit 206, a battery 207, a memory 208, and a switch unit 209. Note that the multiple functional blocks shown in Figure 2 may be implemented as a single hardware module.

[0054] The control unit 201 controls the entire RX1 by executing a control program stored in, for example, memory 208. That is, the control unit 201 controls each functional unit shown in Figure 3. Furthermore, the control unit 201 may also perform control for executing applications other than wireless power transmission. An example of the control unit 201 is configured to include one or more processors such as a CPU or MPU. In addition, the control unit 201 may control the entire RX1 (or the entire smartphone if the RX1 is a smartphone) in cooperation with the OS (Operating System) it is running.

[0055] Furthermore, the control unit 201 may be configured with hardware dedicated to a specific process, such as an ASIC. Alternatively, the control unit 201 may include an array circuit, such as an FPGA, compiled to perform a predetermined process. The control unit 201 stores information that should be remembered while various processes are being executed in the memory 208. The control unit 201 may also measure time using a timer (not shown).

[0056] The UI unit 202 provides various outputs to the user. These outputs include screen displays, LED blinking and color changes, audio output from the speaker, and vibration of the RX1 unit. The UI unit 202 is implemented using an LCD panel, speaker, vibration motor, etc.

[0057] The power receiving unit 203 acquires AC power (AC voltage and AC current) generated by electromagnetic induction caused by electromagnetic waves radiated from the power transmitting antenna 105 of TX2 at the power receiving antenna 205. The power receiving unit 203 then converts the AC power into DC or AC power of a predetermined frequency and outputs power to the charging unit 206, which performs processing to charge the battery 207. In other words, the power receiving unit 203 supplies power to the load in RX1. The above-mentioned GP is the power that is guaranteed to be output from the power receiving unit 203. The power receiving unit 203 is assumed to have the capacity to supply enough power to the charging unit 206 to charge the battery 207 and to output 15 watts of power to the charging unit 206. The switch unit 209 controls whether or not to supply the received power to the battery (load). When the switch unit 209 connects the charging unit 206 and the battery 207, the power received via the power receiving antenna 205 is supplied to the battery 207. In other words, the switch unit 209 is a switching unit that switches whether or not to disconnect the connection between the power receiving antenna 205 and the load, which is the battery 207. If the switch unit 209 disconnects the connection between the charging unit 206 and the battery 207, the power received will not be supplied to the battery 207. In Figure 2, the switch unit 209 is located between the charging unit 206 and the battery 207, but it may also be located between the power receiving unit 203 and the charging unit 206. Alternatively, although the switch unit 209 is shown as a separate block in Figure 2, it is also possible to implement the switch unit 209 as part of the charging unit 206. The communication unit 204 communicates with the communication unit 104 of the TX2 for power receiving control based on the WPC standard as described above. The communication unit 204 demodulates the electromagnetic waves input from the power receiving antenna 205 and obtains the information transmitted from the TX2. The communication unit 204 then communicates with TX2 by superimposing a signal relating to the information to be transmitted to TX2 onto the electromagnetic wave through load modulation of the input electromagnetic wave. The communication unit 204 may also communicate with TX2 using a communication standard different from the WPC standard, using an antenna different from the receiving antenna 205, or it may selectively use multiple communication methods to communicate with TX2.

[0058] In addition to storing the control program, memory 208 also stores the states of TX2 and RX1. For example, the state of RX1 is acquired by the control unit 201, and the state of TX2 is acquired by the control unit 101 of TX2, and can be received via the communication unit 204.

[0059] Next, the functional block diagram of the control unit 101 of TX2 will be described with reference to Figure 3(A). The control unit 101 includes a communication control unit 301, a power transmission control unit 302, a foreign object detection unit 303, a power measurement unit 304, and a detection and determination unit 305. The communication control unit 301 performs control communication with RX1 based on the WPC standard via the communication unit 104. For example, the communication control unit 301 receives a power packet from RX1 containing data indicating the power received by RX1 and transmits a response to the power packet. The power transmission control unit 302 controls the power transmission unit 103 and controls the power transmission to RX1.

[0060] The foreign object detection unit 303 performs first foreign object detection based on power loss between the power transmission device and the power receiving device, and second foreign object detection by measuring the Q value of the power transmission antenna 105. In this embodiment, the foreign object detection unit 303 is described as performing foreign object detection by the Q value measurement method as the second foreign object detection, but foreign object detection processing may be performed using other methods. For example, in a TX2 equipped with NFC (Near Field Communication) communication function, foreign object detection may be performed using the opposing device detection function according to the NFC standard. In addition to detecting foreign objects, the foreign object detection unit 303 can also detect changes in the state on the TX2. For example, it may detect an increase or decrease in the number of RX1s on the TX2. Alternatively, it may detect that an RX1 on the TX2 has moved.

[0061] The power measurement unit 304 measures the power output to RX1 via the power transmission unit 103 and calculates the average output power value for each unit of time. The foreign object detection unit 303 performs foreign object detection processing using the Power Loss method based on the measurement results from the power measurement unit 304 and the power received information from the power receiving device via the communication control unit 301. The detection determination unit 305 determines whether or not to perform foreign object detection based on at least one of the information received from RX1 and the power measured by the power measurement unit 304. The detection determination unit 305 may also determine at least one of the foreign object detection methods (at least one of the first foreign object detection and the second foreign object detection) to perform.

[0062] The communication control unit 301, power transmission control unit 302, foreign object detection unit 303, power measurement unit 304, and foreign object detection determination unit 305 are all implemented as programs that operate in the control unit 101. Each processing unit is configured as an independent program and can operate in parallel while synchronizing the programs through event processing, etc.

[0063] Next, the functional block diagram of the control unit 201 of RX1 will be described with reference to Figure 3(B). The control unit 201 includes a communication control unit 351, a power measurement unit 352, a detection and determination unit 353, and a power receiving control unit 354.

[0064] The communication control unit 351 performs control communication with TX2 via the communication unit 204. The power measurement unit 352 measures the power received from TX2 and transmits data indicating the received power to TX2 via the communication control unit 351. The detection and determination unit 353 determines whether it is necessary to have TX2 perform foreign object detection, and at least one of the first foreign object detection and the second foreign object detection, and transmits a signal to TX2 via the communication control unit 351 to have TX2 perform foreign object detection. The power receiving control unit 354 controls the power receiving unit 203 and controls power transmission with TX2. The power receiving control unit 354 also controls the communication unit 204 and controls the phases and parameters of power transmission.

[0065] The communication control unit 351, power measurement unit 352, detection and determination unit 353, and power receiving control unit 354 are implemented as programs that operate in the control unit 201. Each processing unit is configured as an independent program and can operate in parallel while synchronizing the programs through event processing, etc.

[0066] <6. Example of Power Transfer Phase Processing> In the Power Transfer phase, power is transmitted from TX2 to RX1. Furthermore, foreign objects are detected through the first foreign object detection process. In the first foreign object detection, the CAL process described above first calculates the power loss between TX2 and RX1 in a state without foreign objects (normal power loss) based on the difference between the transmitted power of TX2 and the received power of RX1. Then, TX2 determines that a foreign object is present if the power loss between TX2 and RX1 calculated during subsequent power transmission deviates by a threshold from the standard normal power loss.

[0067] However, in reality, even if foreign matter is present between the power transmission device and the power receiving device, the CAL process may be performed as if no foreign matter is present. In this case, the presence or absence of foreign matter is determined based on the power loss in the state where foreign matter is present, which reduces the accuracy of foreign matter detection. Therefore, in this embodiment, a process is described to prevent a decrease in the accuracy of foreign matter detection by the Power Loss method when CAL processing is performed even though foreign matter is present between TX2 and RX1.

[0068] To perform the first foreign object detection, a CAL process is executed to acquire the data necessary for the first foreign object detection. Before executing this CAL process, RX1 controls TX2 to check whether foreign objects are present on the power transmission equipment using the second foreign object detection method. This makes it possible to perform the CAL process under appropriate conditions (when no foreign objects are present). The operations of TX2 and RX1 to achieve this will be explained using the sequence in Figure 5, the power receiving equipment flowchart in Figure 6, and the power transmission equipment flowchart in Figure 7.

[0069] In this embodiment, we consider a case where CAL processing is required again during the Power Transfer phase when power is transmitted from TX2 to RX1. After RX1 starts receiving power (S501, S601, S701), it determines whether CAL processing is necessary (S502, S602). For example, if the transmitted power is changed to an even higher power, it is necessary to create new calibration points (e.g., 1100, 1103, 1101 in Figure 11), so it is determined that CAL processing is necessary. Alternatively, the temperature of TX2 or RX1 may rise due to power transmission from TX2 to RX1, causing characteristic changes in the circuits and components of TX2 or RX1. In such a case, since a change occurs in the line or curve connecting the calibration points (e.g., the line connecting points 1100, 1103, 1101 in Figure 11), RX1 may determine that CAL processing is necessary to update the calibration points. That is, RX1 may be equipped with a temperature sensor (not shown) and determine whether CAL processing is necessary based on the value of the temperature sensor. In this case, it may be determined that CAL processing needs to be performed if the temperature sensor value has changed by a predetermined value or more from the value at the time of the last CAL processing. Alternatively, RX1 may be equipped with a timer (not shown) and determine whether or not CAL processing needs to be performed based on the time elapsed since power reception began or the time elapsed since the last CAL processing was performed.

[0070] Next, RX1 determines whether predetermined conditions are met (S503, S603). This determines whether there is a high probability that foreign matter is present between TX2 and RX1 (whether predetermined conditions are met). For example, if the time elapsed since the previous foreign matter detection performed by the foreign matter detection unit 303 shown in Figure 3 has been a predetermined amount of time, RX1 determines that there is a high probability that foreign matter is present between TX2 and RX1. On the other hand, if the predetermined amount of time has not elapsed, RX1 determines that there is a low probability that foreign matter is present between TX2 and RX1. If it is determined that there is a low probability of foreign matter presence (No in S603), RX1 transmits the received power value (fourth received power information) of the received power received by RX1 to TX2 in a received power packet (RP packet) (S504, S604, S702). Upon receiving the RP packet, TX2 determines whether the RP packet instructs the execution of CAL processing (S703). In one example, TX2 determines whether an RP packet instructs the execution of CAL processing or first foreign object detection based on whether an RP packet contains an instruction to execute CAL processing or an instruction to execute first foreign object detection. TX2 creates a calibration point based on the received fourth power received information and the corresponding power transmitted (S505, S704) and sends an ACK to TX2 (S506, S705). If TX2 determines that the RP packet is an instruction to execute first foreign object detection, TX2 performs first foreign object detection (S706). If a foreign object is detected (Yes in S707), it notifies RX1 of this (S709) and stops power transmission (S710). If TX2 determines that no foreign object was detected in the first foreign object detection in S706 (No in S707), it notifies RX1 of this (S708) and returns processing to S702.

[0071] After S604, RX1 determines whether it is necessary to perform CAL processing again after a predetermined time has elapsed (S502, S607), and determines whether predetermined conditions are met (S503, S608). This determines whether there is a high probability that foreign matter has entered between the power transmission device and the power receiving device. For example, if a predetermined time has elapsed since the last CAL processing was performed, it is determined that there is a high probability of foreign matter contamination, and before performing CAL processing, the power transmission device checks whether there is any foreign matter between TX2 and RX1 using a foreign matter detection method different from the first foreign matter detection. In order for TX2 to perform a foreign matter detection method different from the first foreign matter detection, RX1 sends, for example, an EPT packet (End Power Transfer packet) to TX2 (S505, S609, S711).

[0072] As a result, TX2 exits the Power Transfer phase and moves to the Selection phase (S712). In other words, it is reset to the state before power transmission. As a result, the power transmission device starts processing again from the Selection phase, and performs foreign object detection (second foreign object detection) using the Q value measurement method, which is performed in the Negotiation phase or Renegotiation phase. In this way, it is possible to perform a second foreign object detection, which is different from the first foreign object detection, before performing the CAL process. This reduces the possibility of foreign objects being introduced between TX2 and RX1 when the CAL process is performed, and enables the first foreign object detection to be performed with higher accuracy.

[0073] In this embodiment, RX1 sends an EPT (End Power Transfer) packet to TX2 to perform the second foreign object detection. However, signals other than EPT packets may be used to perform the second foreign object detection. For example, RX1 may send a signal to TX2 instructing it to transition to the Renegotiation phase. Alternatively, RX1 may instruct TX2 to transition to the Selection phase without changing the reference value for the second foreign object detection.

[0074] As described above, in this embodiment, RX determines whether predetermined conditions for performing second foreign object detection are met before performing CAL processing for first foreign object detection. Furthermore, if it is determined that the predetermined conditions are met, TX is controlled to perform second foreign object detection. This reduces the likelihood of performing CAL processing for first foreign object detection when there is a high probability that a foreign object is present between TX2 and RX1, thereby preventing a decrease in the accuracy of foreign object detection by first foreign object detection.

[0075] <Second Embodiment> In the first embodiment, a method was described for controlling the power transmission device to perform second foreign object detection by terminating the Power Transfer phase when it is determined that second foreign object detection should be performed before the CAL process for first foreign object detection is performed. In the second embodiment, a method was described for controlling the power transmission device to perform second foreign object detection in a shorter time when it is determined that the CAL process necessary for performing first foreign object detection is required. Note that the same configuration, functions, and processes as in the first embodiment will not be described.

[0076] For the first foreign object detection, CAL processing is required. Before executing the CAL processing, RX1 controls TX2 to check whether foreign objects are present on the power transmission equipment using the second foreign object detection method. If the CAL processing is performed during the Power Transfer phase, the second foreign object detection is also performed during the Power Transfer phase, making it possible to check whether foreign objects are present on the power transmission equipment in a shorter time compared to the first embodiment.

[0077] The operation of TX2 and RX1 to achieve this will be explained with reference to the sequence in Figure 8, the flowchart of the power receiving device in Figure 9, and the flowchart of the power transmitting device in Figure 10.

[0078] First, TX2 begins transmitting power to RX1, and RX1 begins receiving power (S801, S901, S1001). After starting to receive power, RX1 determines whether it is necessary to perform a calibration process (S802, S902). For example, if the transmitted power changes, such as becoming even higher, it is necessary to create new calibration points (e.g., 1100, 1103, 1101 in Figure 11), and therefore it is determined that a calibration process is necessary. Alternatively, the temperature of TX2 or RX1 may rise due to power transmission, causing characteristic changes in the circuits and components of TX2 or RX1, which may cause changes in the line or curve connecting the calibration points (e.g., the line connecting 1100, 1103, 1101 in Figure 11). In this case, it is determined that a calibration process is necessary because the calibration points need to be updated.

[0079] Next, it is determined whether the predetermined conditions for performing a second foreign object detection are met (S803, S903). This determines whether there is a high probability that a foreign object is present between TX2 and RX1. For example, if a predetermined amount of time has elapsed since the previous foreign object detection performed by the foreign object detection unit 303 shown in Figure 3, it is determined that there is a high probability that a foreign object is present between TX2 and RX1. If the predetermined amount of time has not elapsed, it is determined that there is a low probability that a foreign object is present. If it is determined that there is a low probability of foreign object presence (No in S903), RX1 sends data corresponding to the power received by RX1 (fourth power received information) to TX2 in a power received packet (RP packet) (S804, S904). When TX2 receives the RP packet (S1002), it performs CAL processing (S805, S1003), and if there are no problems as a result of the CAL processing, it sends an ACK to TX2 (S806, S1004). Based on the results of the CAL process, TX2 performs foreign object detection at predetermined timings during power transmission using the first foreign object detection method (S807, S1005). After a certain period of time has elapsed, RX1 determines whether it is necessary to perform the CAL process again (S808, S902) and whether predetermined conditions are met (S903, S809). This determines whether there is a high probability that a foreign object is present between TX2 and RX1. In this case, if the elapsed time exceeds the predetermined time, it is determined that there is a high probability of foreign object contamination, and before performing the CAL process, TX2 uses a foreign object detection method different from the Power Loss method to confirm that no foreign object is present between TX2 and RX1. To do this, RX1 instructs TX2 to temporarily suspend power transmission (S905, S810). Upon receiving the instruction to temporarily suspend power transmission (S1006), TX2 temporarily suspends power transmission (S1007, S811). Then, RX1 requests TX2 to perform foreign object detection (second foreign object detection) using the Q-value measurement method (S906, S812). RX1 then controls the switch unit 209 to disconnect the load (battery, etc.) (S907, S813). This is because if the load of RX1 is connected when performing the second foreign object detection, foreign object detection cannot be performed, or the accuracy of foreign object detection will decrease.Then, when TX2 receives an instruction to perform foreign object detection using the Q-factor measurement method (S1008, S812), it performs foreign object detection using the Q-factor measurement method (S1009, S814). After a predetermined time has elapsed for TX2 to perform foreign object detection using the Q-factor measurement method (S908, S815), RX1 connects the load. If TX2 does not detect any foreign object as a result of the second foreign object detection (No in S1010), TX2 notifies RX1 that it did not detect any foreign object (S1011, S816). If RX1 receives notification from TX2 that TX2 did not detect any foreign objects (No in S909), RX1 instructs TX2 to resume power transmission (S910, S817). Upon receiving the instruction to resume power transmission (S1012), TX2 resumes power transmission (S1013). If the second foreign object detection confirms that there are no foreign objects between TX2 and RX1, RX1 returns to S902 to determine whether to perform CAL processing (S902, S818) and whether predetermined conditions are met (S903, S819). If RX1 determines that the predetermined conditions are met, it decides to perform CAL processing and transmits data for executing CAL processing (fifth power received information) to TX2 via RP (S904, S820). When TX2 receives an RP (S1002, S820), it calculates the power loss and performs CAL processing (S1003, S821), and sends an ACK to RX1 (S1004, S822). If TX2 detects a foreign object in S1010, it notifies RX1 that a foreign object has been detected (S1015) and stops power transmission (S1016). If RX1 receives notification from the power transmission device that a foreign object has been detected (Yes in S909), it may send an EPT packet to TX2 (S911) and stop power transmission. As described above, according to this embodiment, it is possible to perform a second foreign object detection, which is different from the first foreign object detection, in a shorter time before performing CAL processing for the first foreign object detection. This makes it possible to prevent foreign objects from getting between TX2 and RX1 when CAL processing is performed, which would reduce the accuracy of the first foreign object detection.

[0080] <Third Embodiment> In the second embodiment, when foreign object detection is performed using the Power Loss method, a pause packet is sent to the power transmission equipment requesting a temporary interruption (momentary power outage), and a method is described in which the power transmission equipment is controlled to perform the Q-value measurement method before the CAL processing required for foreign object detection. In the third embodiment, a method is described in which the second foreign object detection is controlled to be performed during the Power Transfer phase without adding new packets (protocols) to the existing WPC standard, and a method is described in which it is possible to check whether foreign objects are mixed into the power transmission equipment in a shorter time. This makes it possible to ensure compatibility while reducing the verification required by adding new packets (protocols). Note that the same configurations, functions, or processes as in the first or second embodiment will not be described.

[0081] The operation of TX2 and RX1 according to this embodiment will be explained below using the flowchart of RX1 in Figure 15, the flowchart of TX2 in Figure 16, and the processing sequence in Figure 14.

[0082] First, TX2 begins supplying power to RX1, and RX1 begins receiving power (S1501, S1601, S1401). After starting to receive power, RX1 determines whether it is necessary to perform CAL processing (S1502, S1402). For example, if the power supply changes to an even higher level, it is necessary to create new calibration points (e.g., 1100, 1103, 1101 in Figure 11), and therefore it is determined that CAL processing is necessary. Alternatively, the temperature of TX2 or RX1 may rise due to power supply, causing changes in the characteristics of the circuit and components, which may cause changes in the line or curve connecting the calibration points (e.g., the line connecting 1100, 1103, 1101 in Figure 11). In this case, RX1 determines that it is necessary to perform CAL processing to update the calibration points. Next, RX1 determines whether the predetermined conditions for performing second foreign object detection are met (S1503, S1403). This determines whether there is a high probability that foreign matter is present between TX2 and RX1. For example, if a predetermined amount of time has not elapsed since the previous foreign matter detection (first or second foreign matter detection) performed by the foreign matter detection unit 303 shown in Figure 3, RX1 determines that there is a low probability that foreign matter is present between TX2 and RX1. If more than a predetermined amount of time has elapsed since the previous foreign matter detection, RX1 determines that there is a high probability that foreign matter is present between TX2 and RX1.

[0083] If RX1 determines that the possibility of foreign matter contamination is low, it transmits the received power value (fourth received power information) of the power received by RX1 to TX2 via RP (S1504, S1404). TX2 receives the RP (S1602) and performs CAL processing (S1603, S1405). Then, TX2 determines whether the received power value in the received Power Packet and the calculated power loss value are appropriate (S1604, S1506). This determination is made based, for example, on whether the received power value in the received RP is greater than a predetermined threshold, or whether the calculated power loss value is greater than a predetermined threshold. If TX2 determines that there is no problem with the received power value in the received RP, TX2 sends an ACK to RX1 (S1605, S1507). Then, during power transmission, TX2 performs a first foreign object detection based on the Power Loss method, which is the first foreign object detection method, at a predetermined timing (S1606, S1422). After a predetermined time, RX1 determines whether it is necessary to perform CAL processing again (S1502, S1408). If it is determined that CAL processing is necessary, it then determines whether predetermined conditions are met (S1503, S1409). If it is determined that there is a high possibility of foreign object contamination, such as a long time having passed since the previous foreign object detection, RX1 sends a signal to TX2 to perform a second foreign object detection. For example, instead of the received power value of the power received by RX1, RX1 sends an RP packet to TX2 with a received power value that TX2 determines to be inappropriate (S1505, S1410). This value may be, for example, the maximum or minimum value of the received power value that can be set in the RP packet. Alternatively, it may be a predetermined value to cause TX2 to perform a second foreign object detection. This can also be achieved by storing a value corresponding to the request to perform a second foreign object detection on TX2 in a section of the RP that holds information other than the received power value. In another example, TX2 may be made to perform a second foreign object detection by sending RP packets to TX2 multiple times in a row within a predetermined time.

[0084] Then, TX2 performs CAL processing (calculation of power loss value) based on the information contained in the received RP (S1603, S1411). Then, TX2 determines whether the received power value in the received RP or the calculated power loss value is appropriate (S1604, S1412). At this time, as described above, if RX1 transmits an RP with a value that TX2 determines to be inappropriate as the received power value, TX2 will determine that the received power value in the RP or the calculated power loss value is inappropriate. In other words, by RX1 transmitting a clearly abnormal value as the received power value to TX2 via RP, TX2 can recognize that RX1 is requesting the execution of the second foreign object detection. Similarly, if RX1 transmits a predetermined value as the received power value to TX2 via RP to cause TX2 to perform the second foreign object detection, TX2 can recognize that RX1 is requesting the execution of the second foreign object detection. Alternatively, RX1 can store information in the RP (Reactor Program) that requests TX2 to perform a second foreign object detection, in a location that holds information other than the received power value. This allows TX2 to recognize that RX1 is requesting the second foreign object detection. TX2 then sends a NAK (Notified Acknowledgment) to RX1 for the received RP (S1607, S1413). This allows RX1 to recognize that TX2 is attempting to perform a second foreign object detection using the Q-factor measurement method.

[0085] When RX1 recognizes that TX2 is about to perform a second foreign object detection, it controls the switch unit 209 to disconnect the load (battery, etc.) (S1506, S1414). This is because, when foreign object detection is performed using the Q-factor measurement method, if the load of RX1 is connected, foreign object detection using the Q-factor measurement method cannot be performed, or the accuracy of foreign object detection will decrease. Therefore, if TX2 is performing a foreign object detection method other than the Q-factor measurement method that does not require disconnecting the load, the process in S1414 is not necessary.

[0086] Then, TX2 performs foreign object detection using the second foreign object detection method, the Q-factor measurement method (S1608, S1415). After RX1 waits for a predetermined time for TX2 to perform foreign object detection using the Q-factor measurement method, RX1 controls the switch unit 209 to reconnect the load (battery, etc.) (S1507, S1416). Then, TX2 determines whether or not it has detected a foreign object based on the results of the foreign object detection using the Q-factor measurement method (S1609, S1417). If TX2 does not detect a foreign object, it starts supplying power. At this time, TX2 may notify RX1 that it did not detect a foreign object. RX1 determines whether or not it has received notification from TX2 that a foreign object has been detected (S1507), and if there is no notification after a predetermined time, it determines that no foreign object was detected and returns to S1502. Alternatively, if TX2 notifies that no foreign object was detected, it may be determined that no foreign object was detected and the process returns to S1502. If TX2 detects a foreign object in S1609, TX2 notifies RX1 that a foreign object has been detected (S1610). When RX1 receives notification from TX2 that a foreign object has been detected, it may send an EPT to TX2 (1509) and stop power transmission.

[0087] RX1 determines in S1502 that it needs to perform CAL processing, and if TX2 performs a second foreign object detection and determines that no foreign object is present, then in S1503 it determines that the predetermined conditions are met (the possibility of foreign object contamination is low). Then, in S1504, it sends RP (fifth power received information) to TX2 again (S1504, S1418). At this time, the power received value of the power received by RX1 is stored in RP. TX2 receives the RP (S1602, S1418), performs CAL processing based on the received RP (S1603, S1419), and determines whether the received power value in the received RP or the calculated power loss value is appropriate (S1604, S1420). If it is determined to be appropriate and the CAL processing is completed, TX2 sends an ACK to RX1 (S1605, S1421). Then, TX2 transmits power to RX1 and, at a predetermined timing, performs first foreign object detection based on the results of the CAL processing described above (S1606).

[0088] In the embodiment described above, TX2 decided in S1604 whether to perform first foreign object detection or second foreign object detection based on the RP information from RX1. However, TX2 may decide which foreign object detection to perform. That is, TX2 may make a determination in the same manner as in S1502 and S1503, and if it determines to perform first foreign object detection, it may send an ACK (S1605), and if it determines to perform second foreign object detection, it may send a NAK (S1607).

[0089] Therefore, without adding new packet (protocol) types to the existing WPC standard, it is possible to perform a second foreign object detection before executing CAL processing, and quickly check whether foreign objects are present on the power transmission equipment.

[0090] <Fourth Embodiment> In the second and third embodiments, a method was described for checking the presence or absence of foreign matter between TX2 and RX1 using a second foreign matter detection method, which is different from the first foreign matter detection method, before executing the CAL process used for the first foreign matter detection. In one example, the order in which the CAL process and the second foreign matter detection are performed may be reversed, and the presence or absence of foreign matter between TX2 and RX1 may be checked using a second foreign matter detection method, which is different from the first foreign matter detection method, after the CAL process has been executed. This is because, if the second foreign matter detection is performed after the CAL process and it is determined that there is foreign matter between TX2 and RX1, the CAL process can be re-executed, thereby preventing the first foreign matter detection from being performed using the results of the CAL process when foreign matter is present.

[0091] The operation of TX2 and RX1 when the order of execution of the CAL processing and the second foreign object detection in the second embodiment is reversed is shown in the processing sequence diagrams of RX1 and TX2 in Figure 17 and the flowchart of RX1 in Figure 18. The processing of TX2 is the same as the flowchart of TX2 in the second embodiment shown in Figure 8. In addition, in the processing sequence diagram of Figure 17 and the flowchart of Figure 18, the same reference numerals are used for the same processes as in Figures 8 and 9, and their explanation is omitted.

[0092] If RX1 determines that the predetermined conditions for performing the second foreign object detection are met (Yes in S903), it sends a Received Power Packet (RP) containing power reception information for CAL processing to TX2 (S1801, S820). Upon receiving the RP, TX2 calculates the power loss value based on the power reception information (fifth power reception information) contained in the RP and performs CAL processing (S821). RX1 also requests TX2 to perform the second foreign object detection (S906, S812), and if TX2 detects a foreign object through the second foreign object detection (Yes in S909), it sends an EPT (S911) to perform CAL processing again. This prevents the first foreign object detection from being performed based on the reference power during CAL processing when a foreign object is present between TX2 and RX1.

[0093] In this embodiment, CAL processing is performed immediately upon TX2 receiving RP in S1801, but in one example, the execution of CAL processing may be delayed for a predetermined time. For example, if TX2 does not receive a request from RX1 to temporarily suspend power transmission or to perform a second foreign object detection within a predetermined time after receiving RP, CAL processing may be performed using the received RP. If TX2 does receive a request from RX1 to temporarily suspend power transmission or to perform a second foreign object detection, CAL processing may be performed after the second foreign object detection. In this case, TX2 calculates the power loss value and sends an ACK before the second foreign object detection, but the calibration point may be created after the second foreign object detection. That is, the calibration point may be created after the processing in S1010 when no foreign object is detected by the second foreign object detection (No in S1010).

[0094] In another example, if RX1 receives notification from TX2 in S909 that a foreign object has been detected, it may delete the calibration point created in S1801 in S911.

[0095] Alternatively, TX2, which has sent a notification to RX1 in S816 of Figure 17 indicating the detection of a foreign object, may control the system so as not to perform the first foreign object detection using the region corresponding to the calibration point created in S821. For example, in the example in Figure 11, TX2, which has detected a foreign object in S816 after creating the calibration point 1101 in S821 of Figure 17, does not need to transmit power at a power level greater than Pt3 until it re-executes the CAL process of Pt2. Alternatively, TX2 does not need to perform the first foreign object detection while transmitting power at a power level greater than Pt3.

[0096] This prevents the first foreign object detection from being performed based on CAL processing that was executed when there was a high probability of foreign objects being present between TX2 and RX1, thereby preventing a decrease in the detection accuracy of the first foreign object detection.

[0097] <Fifth Embodiment> In the fourth embodiment, the order in which the CAL processing and the second foreign object detection are performed is reversed compared to the second embodiment. The CAL processing for the first foreign object detection is performed first, and then a process is described in which the presence or absence of a foreign object between TX2 and RX1 is confirmed by a second foreign object detection that is different from the first foreign object detection. In this embodiment, the processing of TX2 and RX1 when the order in which the CAL processing and the second foreign object detection are performed is reversed compared to the third embodiment is described.

[0098] The operation of TX2 and RX1 when the order of execution of the CAL processing and the second foreign object detection in the third embodiment is reversed is shown in the processing sequence diagrams of RX1 and TX2 in Figure 19 and the flowchart of RX1 in Figure 20. The processing of TX2 is the same as the flowchart of TX2 in the third embodiment shown in Figure 16. In Figures 19 and 20, the same reference numerals are used for processing that is the same as in Figures 14 and 15 of the third embodiment, and their explanation is omitted.

[0099] If RX1 determines that the predetermined conditions for performing the second foreign object detection are met (Yes in S1503), it transmits a Received Power Packet (RP) containing power reception information for CAL processing to TX2 (S2001, S1418). Upon receiving the RP, TX2 calculates the power loss value based on the power reception information (fifth power reception information) contained in the RP and performs CAL processing (S1419). RX1 also transmits an RP or a predetermined signal to TX2 requesting the second foreign object detection (S1505, S1410). If TX2 detects a foreign object through the second foreign object detection (Yes in S1508), it transmits an EPT (S1509) to perform CAL processing again. This prevents the first foreign object detection from being performed based on the reference power during CAL processing when a foreign object is present between TX2 and RX1.

[0100] In this embodiment, CAL processing is performed immediately upon TX2 receiving RP in S1411. However, in one example, the execution of CAL processing may be delayed for a predetermined time. This is the same as in the fourth embodiment, so the explanation is omitted.

[0101] Furthermore, in this embodiment as well, if TX2 is configured to perform second foreign object detection when power packets are received continuously within a predetermined time, it is not necessary to include an instruction to perform second foreign object detection in the power packets.

[0102] <Sixth Embodiment> In the second embodiment, a process was described in which a second foreign object detection method, different from the first foreign object detection method, is used to check for the presence or absence of foreign objects between TX2 and RX1, before instructing the execution of the CAL process used in the first foreign object detection.

[0103] In the fourth embodiment, after instructing the execution of the CAL process used in the first foreign object detection, a process was described in which the presence or absence of foreign objects between TX2 and RX1 is confirmed by a second foreign object detection method that is different from the first foreign object detection method.

[0104] In this embodiment, the second and fourth embodiments are combined to describe a process that checks for the presence or absence of foreign matter between TX2 and RX1 using a second foreign matter detection method different from the first foreign matter detection method, both before and after instructing the execution of the CAL process used in the first foreign matter detection method.

[0105] Note that the same reference numerals are used for the same processes, configurations, and functions as in the first to fifth embodiments, and their explanations are omitted.

[0106] The processes S2101 to S2108 in Figure 21 are the same as those in S810 to S817, so their explanation is omitted. Similarly, the processes S2201 to S2206 in Figure 22 are the same as those in S905 to S910, so their explanation is omitted.

[0107] As shown in Figures 21 and 22, by performing a second foreign object detection before and after TX2 executes the CAL process, it becomes possible to detect if foreign objects are introduced or removed between TX2 and RX1 during the CAL process. This allows for a more accurate determination of the validity of the CAL process results.

[0108] <Seventh Embodiment> In the third embodiment, a process was described in which a second foreign object detection method, different from the first foreign object detection method, is used to check for the presence or absence of foreign objects between TX2 and RX1, before instructing the execution of the CAL process used in the first foreign object detection.

[0109] In the fifth embodiment, after instructing the execution of the CAL process used in the first foreign object detection, a process was described in which the presence or absence of foreign objects between TX2 and RX1 is confirmed by a second foreign object detection method that is different from the first foreign object detection method.

[0110] In this embodiment, the third and fifth embodiments are combined to describe a process that checks for the presence or absence of foreign matter between TX2 and RX1 using a second foreign matter detection method different from the first foreign matter detection method, both before and after instructing the execution of the CAL process used in the first foreign matter detection method.

[0111] Note that the same reference numerals are used for the same processes, configurations, and functions as in the first to fifth embodiments, and their explanations are omitted.

[0112] The processes S2301 and S2302 in Figure 23 are the same as those in S1610 and S1510, so their explanation is omitted. Similarly, the processes S2303 to S2309 in Figure 23 are the same as those in S1410 to S1416 and S2301 and S2302, so their explanation is omitted. Furthermore, the processes S2401 to S2405 in Figure 24 are the same as those in S1505 to S1510, so their explanation is omitted.

[0113] As shown in Figures 23 and 24, by performing a second foreign object detection before and after TX2 executes the CAL process, it becomes possible to detect whether foreign objects have been introduced or removed between TX2 and RX1 during the CAL process. This allows for a more accurate determination of the validity of the CAL process results.

[0114] <Other Embodiments> The first to seventh embodiments described above can be combined as desired. For example, the second and third embodiments may be combined, and the power receiving device may be instructed to perform the second foreign object detection in different ways depending on the model of the power transmitting device, the corresponding WPC standard version, etc.

[0115] In the embodiments described above, a second method of foreign object detection, distinct from the first method, was described as the Q-factor measurement method. Methods for measuring the Q-factor of a power transmission antenna (power transmission coil) include transmitting a signal at the resonant frequency (e.g., a sine wave, square wave, etc.) for a predetermined time and measuring the Q-factor at that resonant frequency. Alternatively, one method involves transmitting signals at multiple frequencies near the resonant frequency multiple times and measuring their Q-factors. Another method involves transmitting a signal (e.g., a pulse wave) having at least some of the frequency components of multiple frequencies to be measured once, and performing calculations (e.g., Fourier transform) on the measurement result to measure the Q-factors at multiple frequencies. Alternatively, the above-mentioned signal (electromagnetic wave) may be output, then the signal output may be stopped, and foreign object detection may be performed based on the attenuation state of the signal waveform (electromagnetic wave waveform) (hereinafter referred to as the waveform attenuation method). If the waveform attenuation state is large, it is possible to determine that a foreign object is present. For example, if, after the output of the electromagnetic wave is stopped, the waveform amplitude at time T1 is A1, and the waveform amplitude at time T2 after a predetermined time has elapsed is A2, the waveform attenuation state may be detected by second foreign object detection based on whether the ratio of waveform amplitudes A1 and A2 is greater than a predetermined value. Alternatively, second foreign object detection may be performed based on the difference between waveform amplitudes A1 and A2, the slope of the waveform attenuation (A1-A2) / (T2-T1), the time until the waveform falls below a predetermined amplitude, etc. Alternatively, the Q value is, if the frequency of the electromagnetic wave waveform is f, Q = πf(T2 - T1) / ln(A1 / A2) Since it can be obtained from this, foreign object detection may be performed based on this. Alternatively, the sharpness of the resonance (Q value) may be determined from the measurement results at each of the frequencies mentioned above, and foreign object detection may be performed based on this.

[0116] On the other hand, the second foreign object detection only requires checking that there is no foreign object between TX2 and RX1, so as not to perform the first foreign object detection (foreign object detection using the Power Loss method) using the calibration results when there is a foreign object between TX2 and RX1. For this reason, a foreign object detection method other than the Q-factor measurement method may be applied as the second foreign object detection.

[0117] For example, in addition to the Q value of the transmitting antenna, measurement results such as the resonant frequency of the transmitting antenna, the sharpness of the resonant curve, or the inductor value, the coupling coefficient between the transmitting antenna and the object placed on the power transmission device, and the electrical characteristics of the power transmission section including the transmitting antenna of the power transmission device may also be used. Furthermore, the presence or absence of foreign matter may be determined based on the measurement results of the electrical characteristics at a single frequency, or based on the measurement results of the electrical characteristics at multiple frequencies.

[0118] Furthermore, measuring electrical characteristics at multiple frequencies can be achieved by transmitting signals at each frequency whose electrical characteristics are to be measured (e.g., sine waves, square waves, etc.) multiple times and measuring the electrical characteristics of the signal at each frequency. This method has the advantage of allowing measurements with relatively little computational processing required in the power transmission equipment.

[0119] Alternatively, the electrical characteristics at multiple frequencies can be calculated by transmitting a signal (e.g., a pulsed wave) containing all frequency components at the multiple frequencies whose electrical characteristics are to be measured, and then performing calculations (e.g., Fourier transform) on the measurement results.

[0120] Alternatively, the electrical characteristics at multiple frequencies can be calculated by transmitting a signal containing some of the frequency components of the multiple frequencies whose electrical characteristics are to be measured multiple times, and then performing calculations (e.g., Fourier transform) on the measurement results. This method has the advantage of reducing the number of times the signal for measurement is transmitted, thus allowing for relatively quick measurements.

[0121] Alternatively, as a second foreign object detection method, measurement results from sensors such as photoelectric sensors, eddy current displacement sensors, contact displacement sensors, ultrasonic sensors, image discrimination sensors, and weight sensors implemented in the power transmission equipment may be used.

[0122] Furthermore, in the first to seventh embodiments, a method was described in which the presence or absence of foreign matter between TX2 and RX1 is confirmed by a second foreign matter detection method, which is different from the first foreign matter detection method, before performing the calibration process for first foreign matter detection during the Power Transfer phase. However, the same effect can be obtained by performing the same check for the presence or absence of foreign matter between TX2 and RX1 by a second foreign matter detection method, which is different from the first foreign matter detection method, as described in the first to seventh embodiments, before performing the calibration process during the Calibration phase. In other words, by applying the first to seventh embodiments to the calibration process during the Calibration phase, the possibility of foreign matter being introduced between TX2 and RX1 during the CAL process can be reduced. Also, in the first to seventh embodiments, the Power Loss method was given as the first foreign matter detection method. And the Calibration process (CAL process) was described as estimating the power loss between the power transmission device and the power receiving device under different loads, assuming that there is no foreign matter between the power transmission device and the power receiving device. However, in a broader sense, this Calibration process is a process for acquiring parameters between the power transmission device and the power receiving device necessary for foreign matter detection, assuming that there is no foreign matter between the power transmission device and the power receiving device. Therefore, a foreign object detection method other than the Power Loss method may be applied as the first foreign object detection method. For example, the Q-factor measurement method (Q-FACTOR MEASUREMENT) or the waveform attenuation method described above may be used as the first foreign object detection method. Furthermore, in the calibration process, the Q-factor and waveform attenuation state in the absence of foreign objects may be measured. Based on these results, the threshold for the first foreign object detection can be determined, and the same effect can be obtained by performing foreign object detection.

[0123] The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0124] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of Symbols]

[0125] 1: Power receiving device, 2: Power transmitting device, 3: Charging cradle, 4: Power transmission range

Claims

1. Power transmission means for wirelessly transmitting power to a power receiving device, It has a detection means that performs a first foreign object detection process related to power loss and a second foreign object detection process related to Quality Factor, If a predetermined time has elapsed since the previous second foreign object detection process, the detection means will perform the second foreign object detection process again. The detection means is a power transmission device that performs Calibration related to the first foreign object detection process if no foreign object is detected by the second foreign object detection process performed again.

2. The power transmission device according to Claim 1, wherein if the detection means has not elapsed the predetermined time since the previous second foreign object detection process, it performs the Calibration without repeating the second foreign object detection process.

3. Having receiving means for receiving a packet indicating a request for the second foreign object detection process from the power receiving device, The power transmission device according to claim 1 or 2, wherein the detection means performs the second foreign object detection process after receiving the packet.

4. The power transmission device according to any one of claims 1 to 3, wherein the power transmission means restricts power transmission if a foreign object is detected by the second foreign object detection process which is performed again.

5. A method performed by a power transmission device capable of performing a first foreign matter detection process relating to power loss and a second foreign matter detection process relating to Quality Factor, If a predetermined time has elapsed since the previous second foreign object detection process, the second foreign object detection process will be performed again. A method comprising performing a calibration related to the first foreign object detection process if no foreign object is detected by the second foreign object detection process performed again.

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